Sample records for adjacent non-glacierized basin

  1. Partitioning the Water Budget in a Glacierized Basin

    NASA Astrophysics Data System (ADS)

    O'Neel, S.; Sass, L.; McGrath, D.; McNeil, C.; Myers, K. F.; Bergstrom, A.; Koch, J. C.; Ostman, J. S.; Arendt, A. A.; LeWinter, A.; Larsen, C. F.; Marshall, H. P.

    2017-12-01

    Glaciers couple to the ecosystems in which they reside through their mass balance and subsequent runoff. The unique timing and composition of glacier runoff notably impacts ecological and socio-economically important processes, including thermal modulation of streams, nearshore primary production, and groundwater exchange. Predicting how these linkages will evolve as glaciers continue to retreat requires a better understanding of basin- to region-scale water budgets. Here we develop a partitioned water balance for Alaska's Wolverine Glacier basin for 2016. Our presentation will highlight mass-balance forcing and sensitivity, as well as analyses of hydrometric and geochemical partitioning. These observations provide constraints for hypsometry-based regional projections of glacier change, which form the basis of future biogeochemical scenarios. Local climate records show relatively minor warming and drying over the 1967 -2016 interval, yet the impact on the glacier was substantial; the average annual balance rate over the study interval is -0.5 m/yr. We performed a sensitivity experiment that suggests that elevation-independent processes drive first-order variability in glacier-wide mass balance solutions Analysis of runoff and precipitation data suggest that previously ignored components of the hydrologic cycle (groundwater, evapotranspiration, off-glacier snowpack storage, and snow redistribution) may substantially contribute to the basin wide water budget. Initial geochemical assessments (carbon, water isotopes, major ions) highlight unique source signatures (glacier-derived, snow-melt, groundwater), which will be further explored using a mixing model approach. Applying a range of climate forcings over centennial time-scales suggests the regional equilibrium line altitude is likely to increase by more than 100 m, which will result in extensive glacier area losses. Such changes will likely modify the runoff from this basin by increasing inter-annual streamflow

  2. An inventory and estimate of water stored in firn fields, glaciers, debris-covered glaciers, and rock glaciers in the Aconcagua River Basin, Chile

    NASA Astrophysics Data System (ADS)

    Janke, Jason R.; Ng, Sam; Bellisario, Antonio

    2017-11-01

    An inventory of firn fields, glaciers, debris-covered glaciers, and rock glaciers was conducted in the Aconcagua River Basin of the semiarid Andes of central Chile. A total of 916 landforms were identified, of which rock glaciers were the most abundant (669) and occupied the most total area. Glaciers and debris-covered glaciers were less numerous, but were about five times larger in comparison. The total area occupied by glaciers and debris-covered glaciers was roughly equivalent to the total area of rock glaciers. Debris-covered glaciers and rock glaciers were subcategorized into six ice-content classes based on interpretation of surface morphology with high-resolution satellite imagery. Over 50% of rock glaciers fell within a transitional stage; 85% of debris-covered glaciers were either fully covered or buried. Most landforms occupied elevations between 3500 and 4500 m. Glaciers and firn occurred at higher elevations compared to rock glaciers and debris-covered glaciers. Rock glaciers had a greater frequency in the northern part of the study area where arid climate conditions exist. Firn and glaciers were oriented south, debris-covered glaciers west, and rock glaciers southwest. An analysis of water contribution of each landform in the upper Andes of the Aconcagua River Basin was conducted using formulas that associate the size of the landforms to estimates of water stored. Minimum and maximum water storage was calculated based on a range of debris to ice content ratios for debris-covered glaciers and rock glaciers. In the Aconcagua River Basin, rock glaciers accounted for 48 to 64% of the water stored within the landforms analyzed; glaciers accounted for 15 to 25%; debris-covered glaciers were estimated at 15 to 19%; firn fields contained only about 5 to 8% of the water stored. Expansion of agriculture, prolonged drought, and removal of ice-rich landforms for mining have put additional pressure on already scarce water resources. To develop long

  3. Distribution and transportation of mercury from glacier to lake in the Qiangyong Glacier Basin, southern Tibetan Plateau, China.

    PubMed

    Sun, Shiwei; Kang, Shichang; Huang, Jie; Li, Chengding; Guo, Junming; Zhang, Qianggong; Sun, Xuejun; Tripathee, Lekhendra

    2016-06-01

    The Tibetan Plateau is home to the largest aggregate of glaciers outside the Polar Regions and is a source of fresh water to 1.4 billion people. Yet little is known about the transportation and cycling of Hg in high-elevation glacier basins on Tibetan Plateau. In this study, surface snow, glacier melting stream water and lake water samples were collected from the Qiangyong Glacier Basin. The spatiotemporal distribution and transportation of Hg from glacier to lake were investigated. Significant diurnal variations of dissolved Hg (DHg) concentrations were observed in the river water, with low concentrations in the morning (8:00am-14:00pm) and high concentrations in the afternoon (16:00pm-20:00pm). The DHg concentrations were exponentially correlated with runoff, which indicated that runoff was the dominant factor affecting DHg concentrations in the river water. Moreover, significant decreases of Hg were observed during transportation from glacier to lake. DHg adsorption onto particulates followed by the sedimentation of particulate-bound Hg (PHg) could be possible as an important Hg removal mechanism during the transportation process. Significant decreases in Hg concentrations were observed downstream of Xiao Qiangyong Lake, which indicated that the high-elevation lake system could significantly affect the distribution and transportation of Hg in the Qiangyong Glacier Basin. Copyright © 2016. Published by Elsevier B.V.

  4. Glacier elevation and mass change over the upper Maipo Basin, Central Andes, Chile.

    NASA Astrophysics Data System (ADS)

    Farías, David; Seehaus, Thorsten; Vivero, Sebastian; Braun, Matthias H.; Casassa, Gino

    2017-04-01

    The upper Maipo basin (33° S, 70° W, 5400 km2) is located 15 km from the eastern outskirts of the mega-city of Santiago. The basin is characterized by Mediterranean climate with marked winter and summer seasons and occasionally disturbed by large annual and multi-annual variations in temperature and precipitation (ENSO). The upper Maipo basin is the main glacierized region of Chile, where the last Chilean glacier inventory revealed a glacier extent of about 397.6 km2 distributed over 1009 glaciers larger than 0.01 km2. The glaciers located in this basin represent 2% of the total glacierized area in Chile. The 1009 glaciers in this area, compose of 708 rock glaciers (159.91 km2), 126 glaciarets (5.85 km2) and 175 valley and mountain glaciers (231.84 km2). Our focus in this study is to evaluate the suitability of TanDEM-X to derive geodetic glacier mass balance on small mountain glaciers. Our database comprises different digital elevation models (DEM) from historical cartography based on aerial photographs (1955), SRTM (2000), Lidar data and TanDEM-X (2015). The historical cartography was scanned and georeferenced with the aid of several GCPs derived from the Lidar dataset. The TanDEM-X data was processed using differential interferometry using SRTM C-band DEM as reference. Differences resulting from X- and C-band penetration are considered comparing X- and C-band SRTM data. All DEMs were horizontal and vertically co-registered to each other. Error assessment was done over stable ground (off-glacier). On our poster we present preliminary results about detailed quantification of glacier elevation and mass change in this area.

  5. Human activities and its Responses to Glacier Melt Water Over Tarim River Basin

    NASA Astrophysics Data System (ADS)

    He, Hai; Zhou, Shenbei; Bai, Minghao

    2017-04-01

    Tarim River Basin lies in the south area of Xinjiang Uygur Autonomous Region, the north-west area of China. It is the longest inland river of China. Being far away from ocean and embraced by high mountains, Tarim River Basin is the typical arid region in the world. The intensity of human activities increased rapidly in Tarim River Basin since 1980's and water resources lacking is the major issue restricting the development of social economy. The glacier melt water plays an important role for the regional social and economic development, and it accounts for 40% of mountain-pass runoff. It is a fragile mutual-dependent relationship between local sustainable development and runoff. Under the background of global change glacier melt water process has also changed especially in the arid and semi-arid region. Due to climate change, glacier in Tarim River Basin has melted in an observed way since 1980s, together with increasing trend of annual rainfall and virgin flow in mountain basins. Correspondingly, human activity gets more frequent since 1970s, resulting into the obvious fragile mutual-dependent relationship between basin runoff and water use amount. Through an analysis of meteorological, hydrological and geographical observation data from 1985 to 2015, this thesis make a multi-factor variance analysis of population, cultivation area, industrial development and runoff in upstream and mid-stream of Tarim River under changing conditions. Furthermore, the regulation function of natural factors and water demand management factors on relationship between runoff and water using amount are discussed, including temperature, rainfall, and evaporation, water conservation technology and soil-water exploitation administrative institutions. It concludes that: first, increase in glacier runoff, rainfall amount, and virgin flow haven't notably relieved ecological issue in Tarim River Basin, and even has promoted water use behaviour in different flowing areas and noticeably reduced

  6. Water, ice, and meteorological measurements at South Cascade Glacier, Washington, 2000-01 balance years

    USGS Publications Warehouse

    Krimmel, Robert M.

    2002-01-01

    Winter snow accumulation and summer snow, firn, and ice melt were measured at South Cascade Glacier, Washington, to determine the winter and net balances for the 2000 and 2001 balance years. In 2000, the winter balance, averaged over the glacier, was 3.32 meters, and the net balance was 0.38 meters. The winter balance was the ninth highest since the record began in 1959. The net balance was greater than 33 of the 41 years since 1959. In 2001, the winter balance was 1.90 meters, and net balance was -1.57 meters. The winter balance was lower than all but 4 years since 1959, and the net balance was more negative than all but 5 other years. Runoff was measured from the glacier basin and an adjacent non-glacierized basin. Air temperature, precipitation, humidity, wind speed and solar radiation were measured nearby. Ice displacements were measured for the 1998-2001 period.

  7. Glacier fluctuation using Satellite Data in Beas basin, 1972-2006, Himachal Pradesh, India

    NASA Astrophysics Data System (ADS)

    Dutta, Shruti; Ramanathan, A. L.; Linda, Anurag

    2012-10-01

    Glaciers are widely recognized as sensitive indicators for regional climate change. Very few studies have been conducted to investigate the long term deglaciation status in the Himalaya. In the present study, glaciers in the Beas basin, Himachal Pradesh, India were mapped by interpretation of various glacio-morphological features using the Landsat and IRS images. The mapping of 224 glaciers during the period 1972-2006 reveals that the glacier cover reduced from 419 to 371 km2, witnessing approximately 11.6% deglaciation in the Beas basin. A higher rate of retreat of the glaciers was observed during 1989-2006 as compared to the retreat during 1972-1989. Also, the loss has been more prominent in the glaciers with an areal extent of 2-5 km2. The number of glaciers increased from 224 to 236 due to fragmentation in this period. The average elevation of the ablation zone basin showed an upward shift from 3898 m (1972) to 4171 m (2006) which may be a consequence of a shift in Equilibrium Line Altitude (ELA) reflecting imbalance.

  8. Water, ice, and meteorological measurements at South Cascade Glacier, Washington, 1997 balance year

    USGS Publications Warehouse

    Krimmel, Robert M.

    1998-01-01

    Winter snow accumulation and summer snow, firn, and ice melt were measured at South Cascade Glacier, Washington to determine the winter and net balances for the 1997 balance year. The 1997 winter balance, averaged over the glacier, was 3.71 meters, and the net balance was 0.63 meter. The winter balance was the greatest since 1972 (4.27 meters), and the second largest since the record began in 1959. The net balance, which was positive for the second year in a row, was 1.57 meters greater than the 1977-96 average (-0.94 meter). Runoff was measured from the glacier and an adjacent non-glacierized basin. Air temperature and precipitation were measured nearby. This report makes these data available to the glaciological and climatological community.

  9. Estimating future flood frequency and magnitude in basins affected by glacier wastage.

    DOT National Transportation Integrated Search

    2015-03-01

    We present field measurements of meteorology, hydrology and glaciers and long-term modeled projections of glacier mass balance and : stream flow informed by downscaled climate simulations. The study basins include Valdez Glacier Stream (342 km2 : ), ...

  10. Water, ice, meteorological, and speed measurements at South Cascade Glacier, Washington, 1999 balance year

    USGS Publications Warehouse

    Krimmel, Robert M.

    2001-01-01

    Winter snow accumulation and summer snow, firn, and ice melt were measured at South Cascade Glacier, Washington, to determine the winter and net balances for the 1999 balance year. The 1999 winter snow balance, averaged over the glacier, was 3.59 meters, and the net balance was 1.02 meters. Since the winter balance record began in 1959, only three winters have had a higher winter balance. Since the net balance record began in 1953, only 2 years have had a greater positive net balance than 1999. Runoff was measured from the glacier and an adjacent non-glacierized basin. Air temperature, precipitation, and humidity were measured nearby, and ice speed was measured. This report makes these data available to the glaciological and climatological community.

  11. Malaspina Glacier: a modern analog to the Laurentide Glacier in New England

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gustavson, T.C.; Boothroyd, J.C.

    1985-01-01

    The land-based temperate Malaspina Glacier is a partial analog to the late Wisconsinan Laurentide Ice Sheet that occupied New England and adjacent areas. The Malaspina occupies a bedrock basin similar to basins occupied by the margin of the Laurentide Ice Sheet. Ice lobes of the Malaspina are similar in size to end moraine lobes in southern New England and Long Island,New York. Estimated ice temperature, ablation rates, surface slopes and meltwater discharge per unit of surface area for the Laurentide Ice Sheet are similar to those for the Malaspina Glacier. In a simple hydrologic-fluvial model for the Malaspina Glacier meltwatermore » moves towards the glacier bed and down-glacier along intercrystalline pathways, crevasses and moulins, and a series of tunnels. Regolith and bedrock at the glacier floor, which are eroded and transported by subglacial and englacial streams, are the sources of essentially all fluvio-lacustrine sediment on the Malaspina Foreland. Supraglacial eskers containing coarse gravels occur as much as 100 m above the glacier bed and are evidence that bedload can be lifted hydraulically. Subordinant amounts of sediment are contributed to outwash by small surface streams draining the ice margin. By analogy a similar hydrologic-fluvial system existed along the southeastern margin of the Laurentide Ice Sheet. Subglacial regolith and bedrock eroded from beneath the Laurentide Ice Sheet by meltwater was also the source of most glaciofluvial and glaciolacustrine deposits in southern New England, not sediment carried to the surface of the ice sheet along shear planes and washed off the glacier by meltwater.« less

  12. Glacier changes in the Ravi basin, North-Western Himalaya (India) during the last four decades (1971-2010/13)

    NASA Astrophysics Data System (ADS)

    Chand, Pritam; Sharma, Milap Chand

    2015-12-01

    A glacier inventory of the Ravi basin, north-western Himalaya has been generated for the year 2002 using Landsat ETM + and ASTER Global DEM (GDEM V2) as the baseline data for the change analysis. The Ravi basin consists of 285 glaciers (> 0.02 km2) covering an area of 164.5 ± 7.5 km2, including 71 debris-covered glaciers with an area of 36.1 ± 2.1 km2 (22% of total glacierized area) in 2002. Change analysis based on Corona KH-4B (1971), Worldview (2010) and Landsat 8 OLI/TRIS (2013) images was restricted to a subset of 157 glaciers (covering an area of 121.4 ± 5.4 km2 in 2002) due to cloud cover. Glacier area decreased from 125.8 ± 1.9 km2 (1971) to 119.9 ± 4.8 km2 (2010/13), a loss of 4.7 ± 4.1% or 0.1 ± 0.1% a- 1. The glacier recession rate has decreased, to a minimum for the recent decades (2002-2010/13). The debris-covered glacier area increased by 19.2 ± 2.2% (0.5 ± 0.05% a- 1) in the Ravi basin. However, there were significant variation in its sub-basins i.e. in Budhil and Upper Ravi sub-basin, where the debris-covered area increased by 28.6 ± 3.1% (0.7 ± 0.1% a- 1) and 14 ± 1.6% (0.3 ± 0.04% a- 1), respectively, between 1971 and 2010/13. Field investigation of selected glaciers (2010-2014) supports glacier recession trend from remote sensing data. Glacier retreat rates in the Ravi basin were lower than previously reported for selected glaciers in the similar basin and other basins (e.g. Chenab, Beas, Parbati, Baspa and Tirungkhad) of the Himachal Himalaya.

  13. Water, ice, and meteorological measurements at South Cascade Glacier, Washington, balance year 2002

    USGS Publications Warehouse

    Bidlake, William R.; Josberger, Edward G.; Savoca, Mark E.

    2004-01-01

    Winter snow accumulation and summer snow and ice ablation were measured at South Cascade Glacier, Washington, to estimate glacier mass balance quantities for balance year 2002. The 2002 glacier-average maximum winter snow balance was 4.02 meters, the second largest since 1959. The 2002 glacier summer, net, and annual (water year) balances were -3.47, 0.55, and 0.54 meters, respectively. The area of the glacier near the end of the balance year was 1.92 square kilometers, and the equilibrium-line altitude and the accumulation area ratio were 1,820 meters and 0.84, respectively. During September 20, 2001 to September 13, 2002, the terminus retreated 4 meters, and computed average ice speeds in the ablation area ranged from 7.8 to 20.7 meters per year. Runoff from the subbasin containing the glacier and from an adjacent non-glacierized basin were measured during part of the 2002 water year. Air temperature, precipitation, atmospheric water-vapor pressure, wind speed and incoming solar radiation were measured at selected locations near the glacier.

  14. Contrasting medial moraine development at adjacent temperate, maritime glaciers: Fox and Franz Josef Glaciers, South Westland, New Zealand

    NASA Astrophysics Data System (ADS)

    Brook, Martin; Hagg, Wilfried; Winkler, Stefan

    2017-08-01

    Medial moraines form important pathways for sediment transportation in valley glaciers. Despite the existence of well-defined medial moraines on several glaciers in the New Zealand Southern Alps, medial moraines there have hitherto escaped attention. The evolving morphology and debris content of medial moraines on Franz Josef Glacier and Fox Glacier on the western flank of the Southern Alps is the focus of this study. These temperate maritime glaciers exhibit accumulation zones of multiple basins that feed narrow tongues flowing down steep valleys and terminate 400 m above sea level. The medial moraines at both glaciers become very prominent in the lower ablation zones, where the medial moraines widen, and develop steeper flanks coeval with an increase in relative relief. Medial moraine growth appears somewhat self-limiting in that relief and slope angle increase eventually lead to transport of debris away from the medial moraine by mass-movement-related processes. Despite similarities in overall morphologies, a key contrast in medial moraine formation exists between the two glaciers. At Fox Glacier, the medial moraine consists of angular rockfall-derived debris, folded to varying degrees along flow-parallel axes throughout the tongue. The debris originates above the ELA, coalesces at flow-unit boundaries, and takes a medium/high level transport pathway before subsequently emerging at point-sources aligned with gently dipping fold hinges near the snout. In contrast at Franz Josef Glacier, the medial moraine emerges farther down-glacier immediately below a prominent rock knob. Clasts show a mix of angular to rounded shapes representing high level transport and subglacially transported materials, the latter facies possibly also elevated by supraglacial routing of subglacial meltwater. Our observations confirm that a variety of different debris sources, transport pathways, and structural glaciological processes can interact to form medial moraines within New Zealand

  15. Estimating Glacier Retreat through Satellite Based Observation In the Beas Basin, Himachal Pradesh, India

    NASA Astrophysics Data System (ADS)

    Dutta, Shruti; Ramanathan, Al.; Linda, Anurag

    2010-05-01

    Glaciers are now well recognized as the most reliable indicators of climate (IPCC, 2007), more particularly in the regions where there is an acute paucity in the availability of meteorological database. Subsequently it can be said that monitoring the glaciers is important to assess the overall reservoir health (Kulkarni et al., 2007). Almost negligible studies have been conducted to investigate the deglaciation status in the Indian Himalaya. A change detection analysis of the areal cover of glaciers in the Beas basin, India with the aid of remote sensing techniques in the present study concludes that the Beas basin has witnessed a loss of about 22.49 km2in the last four decades which is about 22% of the area. Another major aspect of this study is the noticeable retreat of the glaciers in the period 1972-1989. The glaciers in the Beas basin show larger area loss in this period as compared to the loss in area during the 1990s and later. Thus, it can be said that in spite of the alarming scenario of a continued recession of the glaciated terrain in the Beas basin, the pace of retreat has been observed to slow down after the 1990s. The loss has been more significant in the glaciers comprising of the area of 2-5 km2range as compared to the other categories. Glaciers in the area range more than 5 km2and less than 2 km2show less variation reflecting not much of significant loss. The total number of glaciers increased in the period of last four decades although not very significantly, indicating fragmentation. The glaciers in the range 0.5-2 km2 show a higher tendency towards fragmentation. The average elevation of the glaciers in the basin underwent an upward shift from 4565 m in the year 1972 to 4629 m in the year 2006 which is a reason for concern. The gradual upward shifting of contours over a period of almost four decades can be a consequence of a shift in Equilibrium Line Altitude (ELA) which has been constantly moving upwards showing a retreat of glaciers in the

  16. Temporal dynamics of suspended sediment transport in a glacierized Andean basin

    NASA Astrophysics Data System (ADS)

    Mao, Luca; Carrillo, Ricardo

    2017-06-01

    Suspended sediment transport can affect water quality and aquatic ecosystems, and its quantification is of the highest importance for river and watershed management. Suspended sediment concentration (SSC) and discharge were measured at two locations in the Estero Morales, a Chilean Andean stream draining a small basin (27 km2) hosting glacierized areas of about 1.8 km2. Approximately half of the suspended sediment yield (470 t year- 1 km- 2) was transported during the snowmelt period and half during glacier melting. The hysteresis patterns between discharge and SSC were calculated for each daily hydrograph and were analysed to shed light on the location and activity of different sediment sources at the basin scale. During snowmelt, an unlimited supply of fine sediments is provided in the lower and middle part of the basin and hysteresis patterns tend to be clockwise as the peaks in SSC precede the peak of discharge in daily hydrographs. Instead, during glacier melting the source of fine sediments is the proglacial area, producing counterclockwise hysteresis. It is suggested that the analysis of hysteretic patterns over time provides a simple concept for interpreting variability of location and activity of sediment sources at the basin scale.

  17. Holocene glacier history of the Lago Argentino basin, Southern Patagonian Icefield

    NASA Astrophysics Data System (ADS)

    Strelin, Jorge A.; Kaplan, Michael R.; Vandergoes, Marcus J.; Denton, George H.; Schaefer, Joerg M.

    2014-10-01

    , and 2c. The Onelli and Ameghino glacier valleys also preserve older Holocene moraines. In the Agassiz, Spegazzini, and Mayo valleys, ice of the late-Holocene advances appears to have overridden landforms equivalent in age to Pearson 1. Perito Moreno Glacier is an extreme case in which ice of historical (Pearson 2c) advances overrode all older Holocene moraines. Based on the distribution and number of moraines preserved, we infer that the response to climate differed among the Lago Argentino outlet glaciers during the Holocene. This led us to examine the effects of climatic and non-climatic factors on individual glaciers. As a consequence, we detected an important effect of the valley geometry (hypsometry) on the timing and magnitude of glacier response to climate change. These results indicate that caution is needed in correlating moraines among glacier forefields without firm morpho-stratigraphic and age control. Finally, we note important similarities and differences between the overall moraine chronology in the Lago Argentino basin and that in other areas of southern South America and elsewhere in the Southern Hemisphere.

  18. The Value of Hydrograph Partitioning Curves for Calibrating Hydrological Models in Glacierized Basins

    NASA Astrophysics Data System (ADS)

    He, Zhihua; Vorogushyn, Sergiy; Unger-Shayesteh, Katy; Gafurov, Abror; Kalashnikova, Olga; Omorova, Elvira; Merz, Bruno

    2018-03-01

    This study refines the method for calibrating a glacio-hydrological model based on Hydrograph Partitioning Curves (HPCs), and evaluates its value in comparison to multidata set optimization approaches which use glacier mass balance, satellite snow cover images, and discharge. The HPCs are extracted from the observed flow hydrograph using catchment precipitation and temperature gradients. They indicate the periods when the various runoff processes, such as glacier melt or snow melt, dominate the basin hydrograph. The annual cumulative curve of the difference between average daily temperature and melt threshold temperature over the basin, as well as the annual cumulative curve of average daily snowfall on the glacierized areas are used to identify the starting and end dates of snow and glacier ablation periods. Model parameters characterizing different runoff processes are calibrated on different HPCs in a stepwise and iterative way. Results show that the HPC-based method (1) delivers model-internal consistency comparably to the tri-data set calibration method; (2) improves the stability of calibrated parameter values across various calibration periods; and (3) estimates the contributions of runoff components similarly to the tri-data set calibration method. Our findings indicate the potential of the HPC-based approach as an alternative for hydrological model calibration in glacierized basins where other calibration data sets than discharge are often not available or very costly to obtain.

  19. Exploring the hydropower potential of future ice-free glacier basins

    NASA Astrophysics Data System (ADS)

    Round, Vanessa; Farinotti, Daniel; Huss, Matthias

    2017-04-01

    The retreat of glaciers over the next century will present new challenges related to water availability and cause significant changes to the landscape. The construction of dams in areas becoming ice-free has previously been suggested as a mitigation measure against changes to water resources in the European Alps. In Switzerland, a number of hydropower dams already exist directly below glaciers, and the hydropower potential of natural lakes left by retreating glaciers has been recognised. We expand these concepts to the regional, and ultimately global, scale to assess the potential of creating hydropower dams in glacier basins, encouraged by advantages such as relatively low ecological and social impacts, and the possibility to replicate the water storage capabilities of glaciers. In a first order assessment, dam volumes are computed using a subglacial topography model and dam walls simulated at the terminus of each glacier. Potential power production is then estimated from projected glacier catchment runoff until 2100 based on the Global Glacier Evolution Model (GloGEM), and penstock head approximated from a global digital elevation model. Based on this, a feasibility ranking system is presented which takes into account various proxies for cost, demand and impact, such as proximity to populations and existing infrastructure, geological risks and threatened species. The ultimate objective is to identify locations of glacier retreat which could most feasibly and beneficially be used for hydropower production.

  20. Energy balance and runoff modelling of glaciers in the Kongsfjord basin in northwestern Svalbard

    NASA Astrophysics Data System (ADS)

    Kohler, J.; Pramanik, A.; van Pelt, W.

    2016-12-01

    Glaciers and ice caps cover 36,000 Km2 or 60% of the land area of the Svalbard archipelago. Roughly 60% of the glaciated area drains to the ocean through tidewater glacier fronts. Runoff from tidewater glaciers is posited to have a significant impact on fjord circulation and thereby on fjord ecosystems. Ocean circulation modelling underway in the Kongsfjord system requires specification of the freshwater amounts contributed by both tidewater and land-terminating glaciers in its basin. The total basin area of Kongsfjord is 1850 km2. We use a coupled surface energy-balance and firn model (Van Pelt et al. 2015) to calculate mass balance and runoff from the Kongsfjord glaciers for the period 1969-2015. Meteorological data from the nearby station at Ny-Ålesund is used for climate forcing in the model domain, with mass balance data at four glaciers in the Kongsfjord watershed used to calibrate model parameters. Precipitation and temperature lapse rates are adjusted on the study glaciers through repeated model runs at mass balance stake locations to match observed and modelled surface mass balance. Long-term discharge measurement at two sites in this region are used to validate the modelled runoff. Spatial and temporal evolution of melt, refreezing and runoff are analyzed, along with the vertical evolution of subsurface conditions. Reference: Van Pelt, W.J.J. & J. Kohler. 2015. Modelling the long-term mass balance and firn evolution of glaciers around Kongsfjorden, Svalbard. J. Glaciol, 61(228), 731-744. Glaciers and ice caps cover 36,000 Km2 or 60% of the land area of the Svalbard archipelago. Roughly 60% of the glaciated area drains to the ocean through tidewater glacier fronts. Runoff from tidewater glaciers is posited to have a significant impact on fjord circulation and thereby on fjord ecosystems. Ocean circulation modelling underway in the Kongsfjord system requires specification of the freshwater amounts contributed by both tidewater and land-terminating glaciers

  1. Snow and glacier change in koshi Basin Himalaya and its response to global warming

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Yang, X.; Yao, T.; Yufeng, D.

    2010-12-01

    Recently, the argument that Himalayan glaciers will completely melt is rather controversial and the U.N.'s leading panel on climate change has apologized for misleading data published in a 2007 report that warned Himalayan glaciers could melt by 2035. Why the gradual melting of Himalayan glaciers makes most of the major media headlines? This is because Himalayan glacier is the headstream of major rivers in South Asia and Southeast Asia and more than 1/6 people live there. If mass of the glaciers melt or even disappear, people who rely on those rivers will be at risk. After this dispute, we need to realize that:”Although the melting rate still need to further study, the Himalayan glaciers are indeed melting. And in these areas, there are more uncertainties to affect water resource, such as snow fall, precipitation, regional temperature changes and so on”. Koshi Basin Himalaya, located in the boundary between China and Nepal, consist of three rivers i.e. Sun Koshi, Arun river (the headwaters of arun river in China called Pengqu) and Tamur. All of them converge to India Ganga River. The total area of Koshi Basin is about ~57,870 km2 and elevation ranges from 21 m (plain) to 8825m (Mountain glacier). This basin has the typical vertical zonation of Himalaya, so we choose it as the study area. Based on the snow cover data observed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on the NASA Terra spacecraft from 2000-2010, the spatial-temporal distribution and variation of snow cover over the koshi basin are statistical analyzed. Glacier changes are also detected from Landsat images in 2000, 2005 and 2010. It is found that snow cover areas are mainly concentrated in the Ridge of Himalaya Mountain. And there are more persistently snow covered areas and glaciers in the South Slope of Himalaya Mountain with aspect to the North Slope, although the mean elevation of the North Slope is higher than south slope. During the decade of 2000-2010, a slight decreasing

  2. Glacier-terminus fluctuations in the Wrangell and Chugach mountains resulting from non-climate controls

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sturm, M.; Hall, D.K.; Benson, C.S.

    Non-climatically controlled fluctuations of glacier termini were studied in two regions in Alaska. In the Wrangell Mountains, eight glaciers on Mt. Wrangell, an active volcano, have been monitored over the past 30 years using terrestrial surveys, aerial photogrammetry and digitally registered satellite images. Results, which are consistent between different methods of measurement, indicate that the termini of most glaciers were stationary or had retreated slightly. However, the termini of the 30-km-long Ahtna Glacier and the smaller Center and South MacKeith glaciers began to advance in the early 1960s and have advanced steadily at rates between 5 and 18 m yr-1more » since then. These three glaciers flow from the summit caldera of ML Wrangell near the active North Crater, where increased volcanic heating since 1964 has melted over 7 x 107 M3 of ice. The authors suspect that volcanic meltwater has changed the basal conditions for the glaciers, resulting in their advance. In College Fjord, Prince William Sound, the terminus fluctuations of two tidewater glaciers have been monitored since 1931 by terrestrial surveying, photogrammetry, and most recently, from satellite imagery. Harvard Glacier, a 40-kmlong tidewater glacier, has been advancing steadily at nearly 20 m yr-1 since 1931, while the adjacent Yale Glacier has retreated at approximately 50 m yr-1 during the same period, though for short periods, both rates have been much higher.« less

  3. An Analytical Model for Basin-scale Glacier Erosion as a Function of Climate and Topography

    NASA Astrophysics Data System (ADS)

    Jaffrey, M.; Hallet, B.

    2017-12-01

    Knowledge about glacier erosion has advanced considerably over the last few decades with the emergence of a firm mechanistic understanding of abrasion and quarrying, the growing sophistication of complex numerical models of glacial erosion and the evolution of glacial landforms, and the increase in data from field studies of erosion rates. Interest in glacial erosion has also intensified and diversified substantially as it is increasingly recognized as a key process affecting the heights of mountains, the overall evolution of mountain belts, and the coupling of climate, erosion, and tectonics. Yet, the general controls of glacier erosion rates have not been addressed theoretically, and the large range of published basin-scale erosion rates, covering more than 3 orders of magnitude, remains poorly understood. To help gain insight into glacier erosion rates at the scale of glacier basins, the only scale for which extensive data exist, we develop analytically a simple budget of the total mechanical energy per unit time, the power, dissipated by a steady state glacier in sliding, S, and viscous deformation, V. We hypothesize that the power for the work of erosion derives solely from S and that the basin wide erosion rate scales with S averaged over the basin. We solve the power budget directly in terms of climatic and topographic parameters, showing explicitly that the source of power to drive both S and V is the gravitational power supplied by the net snow accumulation (mass balance). The budget leads to the simple metric φ=mbΔz2 for the basin average of S with Δz being the glacier basin relief and mb the gradient of the mass balance with elevation. The dependence of φ on the square of the relief arises from both the mass balance's and potential energy's linear increases with elevation. We validate φ using results from a comprehensive field study of erosion rates paired with glaciological data along a transect extending from Southern Patagonia to the Antarctic

  4. Glacier-derived August runoff in northwest Montana

    USGS Publications Warehouse

    Clark, Adam; Harper, Joel T.; Fagre, Daniel B.

    2015-01-01

    The second largest concentration of glaciers in the U.S. Rocky Mountains is located in Glacier National Park (GNP), Montana. The total glacier-covered area in this region decreased by ∼35% over the past 50 years, which has raised substantial concern about the loss of the water derived from glaciers during the summer. We used an innovative weather station design to collect in situ measurements on five remote glaciers, which are used to parameterize a regional glacier melt model. This model offered a first-order estimate of the summer meltwater production by glaciers. We find, during the normally dry month of August, glaciers in the region produce approximately 25 × 106 m3 of potential runoff. We then estimated the glacier runoff component in five gaged streams sourced from GNP basins containing glaciers. Glacier-melt contributions range from 5% in a basin only 0.12% glacierized to >90% in a basin 28.5% glacierized. Glacier loss would likely lead to lower discharges and warmer temperatures in streams draining basins >20% glacier-covered. Lower flows could even be expected in streams draining basins as little as 1.4% glacierized if glaciers were to disappear.

  5. Hydro-glaciological modeling in the Upper Maipo River basin, extratropical Andes Cordillera, with explicit representation of debris-covered glaciers.

    NASA Astrophysics Data System (ADS)

    McPhee, J. P.; Castillo, Y.; Escobar, M.; Pellicciotti, F.

    2014-12-01

    In this work we improve and calibrate a hydro-glaciological model based on a simplified energy balance approach using the WEAP modeling platform for two catchments in the headwaters of the Maipo River Basin, in the Andes Mountains of Central Chile. The Morales Creek catchment includes the San Francisco glacier, a clean glacier occupying 7% of the catchment area. The Pirámide catchment holds the debris-covered Pirámide Glacier, which covers 20% of the catchment area. Detailed field measurements have been carried out on both glaciers to characterize their melt and meteorological regimes. We calibrate an Enhanced Temperature Index melt model against ablation stakes and runoff measurements, and obtain clear differences between the optimal parameters for the clean and debris-covered glaciers. Calibrate melt threshold temperatures are 0,25 and 0,5ºC for the clean and debris-covered glaciers, respectively, while the fraction of net shortwave radiation employed for melting is 90 and 83% for clean and debris-covered glaciers, respectively. These results are coherent with an insulating effect of the debris cover at the Pirámide glacier. The hydrologic contribution of ice melt for the clean, San Francisco glacier is equivalent to 32% of total runoff measured at the Morales Creek outlet during the simulation period; on the other hand, ice melt accounts for 83% of total runoff estimated at the outlet of the Pirámide catchment over the same period. These results are part on an ongoing effort aimed at quantifying cryospheric contribution to the hydrology of the Maipo River basin, one of the key river basins in Chile, on the face of accelerated climate change, and is the first documented work to explicitly include debris-covered glaciers in a context of basin-wide hydrological modeling.

  6. Water, ice, and meteorological measurements at South Cascade glacier, Washington, balance year 2003

    USGS Publications Warehouse

    Bidlake, William R.; Josberger, Edward G.; Savoca, Mark E.

    2005-01-01

    Winter snow accumulation and summer snow and ice ablation were measured at South Cascade Glacier, Washington, to estimate glacier mass-balance quantities for balance year 2003. The 2003 glacier-average maximum winter snow balance was 2.66 meters water equivalent, which was about equal to the average of such balances for the glacier since balance year 1959. The 2003 glacier summer balance (-4.76 meters water equivalent) was the most negative reported for the glacier, and the 2003 net balance (-2.10 meters water equivalent), was the second-most negative reported. The glacier 2003 annual (water year) balance was -1.89 meters water equivalent. The area of the glacier near the end of the balance year was 1.89 square kilometers, a decrease of 0.03 square kilometer from the previous year. The equilibrium-line altitude was higher than any part of the glacier; however, because snow remained along part of one side of the upper glacier, the accumulation-area ratio was 0.07. During September 13, 2002-September 13, 2003, the glacier terminus retreated at a rate of about 15 meters per year. Average speed of surface ice, computed using a series of vertical aerial photographs dating back to 2001, ranged from 2.2 to 21.8 meters per year. Runoff from the subbasin containing the glacier and from an adjacent non-glacierized basin was gaged during part of water year 2003. Air temperature, precipitation, atmospheric water-vapor pressure, wind speed, and incoming solar radiation were measured at selected locations on and near the glacier. Summer 2003 at the glacier was among the warmest for which data are available.

  7. Contemporary suspended sediment dynamics within two partly glacierized mountain drainage basins in western Norway (Erdalen and Bødalen, inner Nordfjord)

    NASA Astrophysics Data System (ADS)

    Beylich, Achim A.; Laute, Katja; Storms, Joep E. A.

    2017-06-01

    This paper focuses on environmental controls, spatiotemporal variability and rates of contemporary fluvial suspended sediment transport in the neighboring, partly glacierized and steep Erdalen (79.5 km2) and Bødalen (60.1 km2) drainage basins in the fjord landscape of the inner Nordfjord in western Norway. Field work, including extended samplings and measurements, was conducted since 2004 in Erdalen and since 2008 in Bødalen. The distinct intra- and inter-annual temporal variability of suspended sediment transport found is mostly controlled by meteorological events, with most suspended sediment transport occurring during pluvial events in autumn (September-November), followed by mostly thermally determined glacier melt in summer (July-August), and by mostly thermally determined snowmelt in spring (April-June). Extreme rainfall events (> 70 mm d- 1) in autumn can trigger significant debris-flow activity that can cause significant transfers of suspended sediments from ice-free surface areas with sedimentary covers into main stream channels and is particularly important for fluvial suspended sediment transport. In years with occurring relevant debris-flow activity the total annual drainage-basin wide suspended sediment yields are strongly determined by these single extreme events. The proportion of glacier coverage, followed by steepness of slopes, and degree of vegetation cover in ice-free surface areas with sedimentary covers are the main controls for the detected spatial variability of suspended sediment yields. The contemporary sediment supply from glacierized surface areas and the Jostedalsbreen ice cap through different defined outlet glaciers shows a high spatial variability. The fact that the mean annual suspended sediment yield of Bødalen is with 31.3 t km- 2 yr- 1 almost twice as high as the mean annual suspended sediment yield of Erdalen (16.4 t km- 2 yr- 1) is to a large extent explained by the higher proportion of glacier coverage in Bødalen (38% of

  8. Runoff generation from neighboring headwater basins with differing glacier coverage using the distributed hydrological model WaSiM, Eklutna, Alaska

    NASA Astrophysics Data System (ADS)

    Ostman, J. S.; Loso, M.; Liljedahl, A. K.; Gaedeke, A.; Geck, J. E.

    2017-12-01

    Many Alaska glaciers are thinning and retreating, and glacier wastage is projected to affect runoff processes from glacierized basins. Accordingly, effective resource management in glacierized watersheds requires quantification of a glacier's role on streamflow generation. The Eklutna catchment (311 km2) supplies water and electricity for Anchorage, Alaska (pop. 300,000) via Eklutna Lake. The Eklutna headwaters include the West Fork (64 km2, 46% glacier), and the East Fork (101 km2, 12% glacier). Total average annual discharge (2009-2015) is similar from the West (42,100 m3) and East (42,200 m3) forks, while specific annual runoff from the West Fork (2940 mm) exceeds that of the East Fork (1500 mm). To better understand what controls runoff, we are simulating the Eklutna annual water budget using a distributed watershed-level hydrological model. We force the Water Flow and Balance Simulation Model (WaSiM) using continuous air temperature, precipitation, wind speed, shortwave incoming radiation, and relative humidity primarily measured in the West Fork basin. We use Eklutna Glacier snow accumulation and ablation to calibrate the snowmelt and glacier sub-modules. Melt season discharge from the West and East forks is used for runoff comparison. Preliminary results show 2013-2015 simulated glacier point balances (accumulation and melt) are within 15% of glacier stake observations. Runoff was effectively modeled in the West Fork (NSE=0.80), while being over-predicted in the East Fork , which we attribute to a lack of forcing data in the less-glacierized basin. The simulations suggest that 78% of West Fork total runoff is from glacier melt, compared with <40% in the East Fork where glacier runoff contribution is higher during low-snow years.

  9. Study on glacier changes from multi-source remote sensing data in the mountainous areas of the upper reaches of Shule River Basin

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Li, H.

    2017-12-01

    The changes of glacier area, ice surface elevation and ice storage in the upper reaches of the Shule River Basin were investigated by the Landsat TM series SRTM and stereo image pairs of Third Resources Satellite (ZY-3)from 2000 to 2015. There are 510 glaciers with areas large than 0.01 km2 in 2015, and the glacier area is 435 km2 in the upper reach of Shule River basin. 96 glaciers were disappeared from 2000 to 2015, and the total glacier area decreased by 57.6±2.68km2 (11.7 %). After correcting the elevation difference between ZY-3 DEM and SRTM and aspect, we found that the average ice surface elevation of glaciers reduced by 2.58±0.6m from 2000 to 2015 , with average reduction 0.172 ±0.04m a-1, and the ice storage reduced by 1.277±0.311km3. Elevation variation of ice surface in different sub-regions reflects the complexity of glacier change. The ice storage change calculated from the sum of single glacier area-volume relationship is glacier 1.46 times higher than that estimated from ice surface elevation change, indicating that the global ice storage change estimated from glacier area-volume change probably overestimated. The shrinkage of glacier increased glacier runoff, and led the significant increase of river runoff. The accuracy of projecting the potential glacier change, glacier runoff and river runoff is the key issues of delicacy water resource management in Shule River Basin.

  10. Surface Hydrological Processes of Rock Glaciated Basins in the San Juan Mountains, Colorado

    NASA Astrophysics Data System (ADS)

    Mateo, E. I.

    2017-12-01

    Glaciers in the western United States have been examined in terms of their summer meltwater contributions to regional hydrological systems. In the San Juan Mountains of Colorado where glaciers do not and cannot exist due to a rising zero-degree isotherm, rock glaciers take the place of valley glaciers during the summer runoff period. Most of the rock glaciers in Colorado are located on a northerly slope aspect, however, there are multiple in the southwest region of the state that occur on different aspects. This study asked how slope aspect and rising air temperatures influenced the hydrological processes of streams below rock glaciers in the San Juan Mountains during the 2016 summer season. This project focused on three basins, Yankee Boy basin, Blue Lakes basin, and Mill Creek basin, which are adjacent to each other and share a common peak, Gilpin Peak. Findings of this one-season study showed that air temperature significantly influenced stream discharge below each rock glacier. Discharge and air temperature patterns indicate a possible air temperature threshold during late summer when rock glacier melt increased at a greater rate. The results also suggest that slope aspect of rock glacier basins influences stream discharge, but temperature and precipitation are likely larger components of the melt regimes. The continuation of data collection during the 2017 summer season has allowed for more detailed analysis of the relationship between air temperature and rock glacier melt. This continual expansion of the original dataset is crucial for understanding the hydrological processes of surface runoff below rock glaciers.

  11. Hydrological processes in glacierized high-altitude basins of the western Himalayas

    NASA Astrophysics Data System (ADS)

    Jeelani, Ghulam; Shah, Rouf A.; Fryar, Alan E.; Deshpande, Rajendrakumar D.; Mukherjee, Abhijit; Perrin, Jerome

    2018-03-01

    Western Himalaya is a strategically important region, where the water resources are shared by China, India and Pakistan. The economy of the region is largely dependent on the water resources delivered by snow and glacier melt. The presented study used stable isotopes of water to further understand the basin-scale hydro-meteorological, hydrological and recharge processes in three high-altitude mountainous basins of the western Himalayas. The study provided new insights in understanding the dominant factors affecting the isotopic composition of the precipitation, snowpack, glacier melt, streams and springs. It was observed that elevation-dependent post-depositional processes and snowpack evolution resulted in the higher isotopic altitude gradient in snowpacks. The similar temporal trends of isotopic signals in rivers and karst springs reflect the rapid flow transfer due to karstification of the carbonate aquifers. The attenuation of the extreme isotopic input signal in karst springs appears to be due to the mixing of source waters with the underground karst reservoirs. Basin-wise, the input-output response demonstrates the vital role of winter precipitation in maintaining the perennial flow in streams and karst springs in the region. Isotopic data were also used to estimate the mean recharge altitude of the springs.

  12. Modeled and measured glacier change and related glaciological, hydrological, and meteorological conditions at South Cascade Glacier, Washington, balance and water years 2006 and 2007

    USGS Publications Warehouse

    Bidlake, William R.; Josberger, Edward G.; Savoca, Mark E.

    2010-01-01

    terminus retreated at a rate of about 13 meters per year during balance year 2006 and at a rate of about 8 meters per year during balance year 2007. Glacier area near the end of balance years 2006 and 2007 was 1.74 and 1.73 square kilometers, respectively. Runoff from the basin containing the glacier and from an adjacent nonglacierized basin was gaged during all or parts of water years 2006 and 2007. Air temperature, wind speed, precipitation, and incoming solar radiation were measured at selected locations on and near the glacier. Air-temperature over the glacier at a height of 2 meters generally was less than at the same altitude in the air mass away from the glacier. Cooling of the air by the glacier increased systematically with increasing ambient air temperature. Empirically based equations were developed to estimate 2-meter-height air temperature over the glacier at five sites from site altitude and temperature at a non-glacier reference site.

  13. Water resources of the Waccasassa River Basin and adjacent areas, Florida

    USGS Publications Warehouse

    Taylor, G.F.; Snell, L.J.

    1978-01-01

    This map report was prepared in cooperation with the Southwest Florida Water Management District which, with the Waccasassa River Basin Board, had jurisdiction over waters within the Waccasassa River basin, the coastal areas adjacent to the basin, and other adjacent areas outside the basin. New water management district boundaries, effective January 1977, place most of the Waccasassa River basin in the Suwannee River Water Management District. The purpose of the report is to provide water information for consideration in land-use and water development which is accelerating, especially in the northeastern part of the study area. It is based largely on existing data in the relatively undeveloped area. Of the total area included in the topographic drainage basin for the Waccasassa River about 72 percent is in Levy County, 18 percent in Alachua County, 9 percent in Gilchrist County, and 1 percent in Marion County. The elongated north-south drainage basin is approximately 50 mi in length, averages 13 mi in width, and lies between the Suwannee River, the St. Johns River, and the Withlacoochee River basins. (Woodard-USGS)

  14. Quantifying present and future glacier melt-water contribution to runoff in a Central Himalayan river basin

    NASA Astrophysics Data System (ADS)

    Prasch, M.; Mauser, W.; Weber, M.

    2012-10-01

    Water supply of most lowland cultures heavily depends on rain and melt-water from the upstream mountains. Especially melt-water release of alpine mountain ranges is usually attributed a pivotal role for the water supply of large downstream regions. Water scarcity is assumed as consequence of glacier shrinkage and possible disappearance due to Global Climate Change, particular for large parts of Central and South East Asia. In this paper, the application and validation of a coupled modeling approach with Regional Climate Model outputs and a process-oriented glacier and hydrological model is presented for a Central Himalayan river basin despite scarce data availability. Current and possible future contributions of ice-melt to runoff along the river network are spatially explicitly shown. Its role among the other water balance components is presented. Although glaciers have retreated and will continue to retreat according to the chosen climate scenarios, water availability is and will be primarily determined by monsoon precipitation and snow-melt. Ice-melt from glaciers is and will be a minor runoff component in summer monsoon-dominated Himalayan river basins.

  15. Global-scale hydrological response to future glacier mass loss

    NASA Astrophysics Data System (ADS)

    Huss, Matthias; Hock, Regine

    2018-01-01

    Worldwide glacier retreat and associated future runoff changes raise major concerns over the sustainability of global water resources1-4, but global-scale assessments of glacier decline and the resulting hydrological consequences are scarce5,6. Here we compute global glacier runoff changes for 56 large-scale glacierized drainage basins to 2100 and analyse the glacial impact on streamflow. In roughly half of the investigated basins, the modelled annual glacier runoff continues to rise until a maximum (`peak water') is reached, beyond which runoff steadily declines. In the remaining basins, this tipping point has already been passed. Peak water occurs later in basins with larger glaciers and higher ice-cover fractions. Typically, future glacier runoff increases in early summer but decreases in late summer. Although most of the 56 basins have less than 2% ice coverage, by 2100 one-third of them might experience runoff decreases greater than 10% due to glacier mass loss in at least one month of the melt season, with the largest reductions in central Asia and the Andes. We conclude that, even in large-scale basins with minimal ice-cover fraction, the downstream hydrological effects of continued glacier wastage can be substantial, but the magnitudes vary greatly among basins and throughout the melt season.

  16. Modeled climate-induced glacier change in Glacier National Park, 1850-2100

    USGS Publications Warehouse

    Hall, M.H.P.; Fagre, D.B.

    2003-01-01

    The glaciers in the Blackfoot-Jackson Glacier Basin of Glacier National Park, Montana, decreased in area from 21.6 square kilometers (km2) in 1850 to 7.4 km2 in 1979. Over this same period global temperatures increased by 0.45??C (?? 0. 15??C). We analyzed the climatic causes and ecological consequences of glacier retreat by creating spatially explicit models of the creation and ablation of glaciers and of the response of vegetation to climate change. We determined the melt rate and spatial distribution of glaciers under two possible future climate scenarios, one based on carbon dioxide-induced global warming and the other on a linear temperature extrapolation. Under the former scenario, all glaciers in the basin will disappear by the year 2030, despite predicted increases in precipitation; under the latter, melting is slower. Using a second model, we analyzed vegetation responses to variations in soil moisture and increasing temperature in a complex alpine landscape and predicted where plant communities are likely to be located as conditions change.

  17. The history of retreat dynamics of Petermann Glacier inferred from submarine glacial landforms

    NASA Astrophysics Data System (ADS)

    Jakobsson, M.; Hogan, K.; Mayer, L. A.; Mix, A. C.; Jerram, K.; Mohammad, R.; Stranne, C.; Eriksson, B.

    2016-12-01

    Preserved submarine glacial landforms produced at the base and margin of ice sheets and outlet glaciers comprise records of past ice dynamics complementary to modern glaciological process studies. The Petermann 2015 Expedition on the Swedish icebreaker Oden systematically mapped approximately 3100 km2 of the seafloor in Petermann Fjord and the adjacent Hall Basin of Nares Strait, northwest Greenland, with an EM122 (12 kHz) multibeam and SBP120 (2-7 kHz) chirp sub-bottom profiler. Complete, overlapping mapping coverage permitted compilation of a high-quality (15x15m) digital terrain model (DTM). In addition, the seafloor at the margin of one of the smaller outlet glaciers draining into the Petermann Fjord and selected shallow areas along the coast were mapped using a small survey boat (RV Skidbladner), equipped with an EM2040 (200-300 kHz) multibeam. High-resolution (2 x 2 m) DTMs were compiled from the RV Skidbladner surveys. The seafloor morphology of Petermann Fjord and adjacent Hall Basin is dominated by a stunning glacial landform record comprising the imprints of Petermann Glacier's retreat dynamics since the Last Glacial Maximum (LGM). The entrance to Petermann Fjord consists of a prominent bathymetric sill formed by a large well-develop grounding zone wedge that undoubtedly represents a stability point during the glacier's retreat history. The deepest entrance to the fjord is 443 m and located on the southern side of this grounding zone wedge. Outside of this grounding zone wedge in Hall Basin, less well developed grounding zones appears to be present. The landform assemblage in between the grounding zones, in particular the lack of retreat ridges, may signify a leap-frog behavior of the glacier's retreat; rapid break-up and disintegration of the outlet glacier causing retreat back to the next stability point dictated by the local bedrock geology. While numerous classical glacial landforms characteristic for fast flowing ice streams are identified, the

  18. Tibetan Plateau glacier and hydrological change under stratospheric aerosol injection

    NASA Astrophysics Data System (ADS)

    Ji, D.

    2017-12-01

    As an important inland freshwater resource, mountain glaciers are highly related to human life, they provide water for many large rivers and play a very important role in regional water cycles. The response of mountain glaciers to future climate change is a topic of concern especially to the many people who rely on glacier-fed rivers for purposes such as irrigation. Geoengineering by stratospheric aerosol injection is a method of offsetting the global temperature rise from greenhouse gases. How the geoengineering by stratospheric aerosol injection affects the mass balance of mountain glaciers and adjacent river discharge is little understood. In this study, we use regional climate model WRF and catchment-based river model CaMa-Flood to study the impacts of stratospheric aerosol injection to Tibetan Plateau glacier mass balance and adjacent river discharge. To facilitate mountain glacier mass balance study, we improve the description of mountain glacier in the land surface scheme of WRF. The improvements include: (1) a fine mesh nested in WRF horizontal grid to match the highly non-uniform spatial distribution of the mountain glaciers, (2) revising the radiation flux at the glacier surface considering the surrounding terrain. We use the projections of five Earth system models for CMIP5 rcp45 and GeoMIP G4 scenarios to drive the WRF and CaMa-Flood models. The G4 scenario, which uses stratospheric aerosols to reduce the incoming shortwave while applying the rcp4.5 greenhouse gas forcing, starts stratospheric sulfate aerosol injection at a rate of 5 Tg per year over the period 2020-2069. The ensemble projections suggest relatively slower glacier mass loss rates and reduced river discharge at Tibetan Plateau and adjacent regions under geoengineering scenario by stratospheric aerosol injection.

  19. Deglaciation and its impact on permafrost and rock glacier evolution: New insight from two adjacent cirques in Austria.

    PubMed

    Kellerer-Pirklbauer, Andreas; Kaufmann, Viktor

    2018-04-15

    Glaciers and permafrost are strongly linked to each other in mid-latitude mountain regions particularly with polythermal glaciers. This linkage is not only climatically defined but also in terms of geomorphic and glaciological processes. We studied two adjacent cirques located in the Central Austria. We focussed on the deglaciation since the Little Ice Age (LIA) maximum (c.1850CE) and its relevance for permafrost and rock glacier evolution since then. One cirque is occupied by a glacier remnant whereas the second one is occupied by an active rock glacier which was partly overridden by a glacier during the LIA. We applied a multidisciplinary approach using field-based techniques including geoelectrics, geodetic measurements, and automatic monitoring as well as historic maps and photographs, remote sensing, and digital terrain analysis. Results indicate almost complete deglaciation by the end of the last millennium. Small-scale tongue-shaped landforms of complex origin formed during the last decades at finer-grained slope deposits below the cirque headwalls. Field evidences and geophysics results proved the existence of widespread sedimentary ice beneath a thin veneer of debris at these slopes. The variable thickness of the debris layer has a major impact on differential ablation and landform evolution in both cirques. The comparison of digital elevation models revealed clear mass losses at both cirques with low rates between 1954 and 2002 and significantly higher rates since then. The central and lower part of the rock glacier moves fast transporting sediments and ice downvalley. In contrast, the upper part of the rock glacier is characterised by low debris and ice input rates. Both effects cause a significant decoupling of the main rock glacier body from its nourishment area leading eventually to rock glacier starvation. This study demonstrates the importance of a decadal-scale and multidisciplinary research approach in determining the development of alpine

  20. A revised Canadian perspective: progress in glacier hydrology

    NASA Astrophysics Data System (ADS)

    Munro, D. Scott

    2005-01-01

    Current research into glacier hydrology is occurring at a time when glaciers around the world, particularly those whose hydrological regimes affect populated areas, are shrinking as they go through a state of perpetual negative annual mass balance. Small glaciers alone are likely to contribute 0·5 to 1 mm year-1 to global sea-level rise, with associated reductions in local freshwater resources, impacts upon freshwater ecosystems and increased risk of hazard due to outburst floods. Changes to the accumulation regimes of glaciers and ice sheets may be partly responsible, so the measurement and distribution of snowfall in glacierized basins, a topic long represented in non-glacierized basin research, is now beginning to receive more attention than it did before, aided by the advent of reliable automatic weather stations that provide data throughout the year. Satellite data continue to be an important information source for summer meltwater estimation, as distributed models, and their need for albedo maps, continue to develop. This further entails the need for simplifications to energy balance components, sacrificing point detail so that spatial calculation may proceed more quickly. The understanding of surface meltwater routing through the glacier to produce stream outflow continues to be a stimulating area of research, as demonstrated by activity at the Trapridge Glacier, Canada, and Canadian involvement in the Haut Glacier d'Arolla, Switzerland. As Canadian glacier monitoring continues to evolve, effort must be directed toward developing situations where mass balance, meltwater generation and flow routing studies can be done together at selected sites. Copyright

  1. 20 years of mass balances on the Piloto glacier, Las Cuevas river basin, Mendoza, Argentina

    NASA Astrophysics Data System (ADS)

    Leiva, J. C.; Cabrera, G. A.; Lenzano, L. E.

    2007-10-01

    Climatic changes of the 20th century have altered the water cycle in the Andean basins of central Argentina. The most visible change is seen in the mountain glaciers, with loss of part of their mass due to decreasing thickness and a substantial recession in the last 100 years. This paper briefly describes the results of glacier mass balance research since 1979 in the Piloto Glacier at the Cajón del Rubio, in the headwaters of Las Cuevas River, presenting new results for the period 1997-2003. Very large interannual variability of net annual specific balance is evident, due largely to variations in winter snow accumulation, with a maximum net annual value of + 151 cm w.e. and a minimum value of - 230 cm w.e. Wet El Niño years are normally associated with positive net annual balances, while dry La Niña years generally result in negative balances. Within the 24-year period, 67% of the years show negative net annual specific balances, with a cumulative mass balance loss of - 10.50 m water equivalent (w.e.). Except for exceptions normally related to El Niño events, a general decreasing trend of winter snow accumulation is evident in the record, particularly after 1992, which has a strong effect in the overall negative mass balance values. The glacier contribution to Las Cuevas River runoff is analysed based on the Punta de Vacas River gauge station for a hypothetical year without snow precipitation (YWSP), when the snowmelt component is zero. Extremely dry years similar to a YWSP have occurred in 1968-1969, 1969-1970 and 1996-1997. The Punta de Vacas gauge station is located 62 km downstream from Piloto Glacier, and the basin contains 3.0% of uncovered glacier ice and 3.7% of debris-covered ice. The total glacier contribution to Las Cuevas River discharge is calculated as 82 ± 8% during extremely dry years. If glacier wastage continues at the present trend as observed during the last 2 decades, it will severely affect the water resources in the arid central Andes of

  2. Influence of spatial discretization, underground water storage and glacier melt on a physically-based hydrological model of the Upper Durance River basin

    NASA Astrophysics Data System (ADS)

    Lafaysse, M.; Hingray, B.; Etchevers, P.; Martin, E.; Obled, C.

    2011-06-01

    SummaryThe SAFRAN-ISBA-MODCOU hydrological model ( Habets et al., 2008) presents severe limitations for alpine catchments. Here we propose possible model adaptations. For the catchment discretization, Relatively Homogeneous Hydrological Units (RHHUs) are used instead of the classical 8 km square grid. They are defined from the dilineation of hydrological subbasins, elevation bands, and aspect classes. Glacierized and non-glacierized areas are also treated separately. In addition, new modules are included in the model for the simulation of glacier melt, and retention of underground water. The improvement resulting from each model modification is analysed for the Upper Durance basin. RHHUs allow the model to better account for the high spatial variability of the hydrological processes (e.g. snow cover). The timing and the intensity of the spring snowmelt floods are significantly improved owing to the representation of water retention by aquifers. Despite the relatively small area covered by glaciers, accounting for glacier melt is necessary for simulating the late summer low flows. The modified model is robust over a long simulation period and it produces a good reproduction of the intra and interannual variability of discharge, which is a necessary condition for its application in a modified climate context.

  3. Testing geographical and climatic controls on glacier retreat

    NASA Astrophysics Data System (ADS)

    Freudiger, Daphné; Stahl, Kerstin; Weiler, Markus

    2015-04-01

    Glacier melt provides an important part of the summer discharge in many mountainous basins. The understanding of the processes behind the glacier mass losses and glacier retreats observed during the last century is therefore relevant for a sustainable management of the water resources and reliable models for the prediction of future changes. The changes in glacier area of 49 sub-basins of the Rhine River in the Alps were analyzed for the time period 1900-2010 by comparing the glacier areas of Siegfried maps for the years 1900 and 1940 with satellite derived glacier areas for the years 1973, 2003 and 2010. The aim was to empirically investigate the controls of glacier retreat and its regional differences. All glaciers in the glacierized basins retreated over the last 110 years with some variations in the sub-periods. However, the relative changes in glacier area compared to 1900 differed for every sub-basin and some glaciers decreased much faster than others. These observed differences were related to a variety of different potential controls derived from different sources, including mean annual solar radiation on the glacier surface, average slope, mean glacier elevation, initial glacier area, average precipitation (summer and winter), and the precipitation catchment area of the glacier. We fitted a generalized linear model (GLM) and selected predictors that were significant to assess the individual effects of the potential controls. The fitted model explains more than 60% of the observed variance of the relative change in glacier area with the initial area alone only explaining a small proportion. Some interesting patterns emerge with higher average elevation resulting in higher area changes, but steeper slopes or solar radiation resulting in lower relative glacier area changes. Further controls that will be tested include snow transport by wind or avalanches as they play an important role for the glacier mass balance and potentially reduce the changes in glacier

  4. Afghanistan Glacier Diminution

    NASA Astrophysics Data System (ADS)

    Shroder, J. F.; Bishop, M.; Haritashya, U.; Olsenholler, J.

    2008-12-01

    Glaciers in Afghanistan represent a late summer - early fall source of melt water for late season crop irrigation in a chronically drought-torn region. Precise river discharge figures associated with glacierized drainage basins are generally unavailable because of the destruction of hydrological gauging stations built in pre-war times although historic discharge data and prior (1960s) mapped glacier regions offer some analytical possibilities. The best satellite data sets for glacier-change detection are declassified Cornona and Keyhole satellite data sets, standard Landsat sources, and new ASTER images assessed in our GLIMS (Global Land Ice Measurements from Space) Regional Center for Southwest Asia (Afghanistan and Pakistan). The new hyperspectral remote sensing survey of Afghanistan completed by the US Geological Survey and the Afghanistan Ministry of Mines offers potential for future detailed assessments. Long-term climate change in southwest Asia has decreased precipitation for millennia so that glaciers, rivers and lakes have all declined from prehistoric and historic highs. As many glaciers declined in ice volume, they increased in debris cover until they were entirely debris-covered or became rock glaciers, and the ice was protected thereby from direct solar radiation, to presumably reduce ablation rates. We have made a preliminary assessment of glacier location and extent for the country, with selected, more-detailed, higher-resolution studies underway. In the Great Pamir of the Wakhan Corridor where the largest glaciers occur, we assessed fluctuations of a randomly selected 30 glaciers from 1976 to 2003. Results indicate that 28 glacier-terminus positions have retreated, and the largest average retreat rate was 36 m/yr. High albedo, non-vegetated glacier forefields formed prior to 1976, and geomorphological evidence shows apparent glacier-surface downwasting after 1976. Climatic conditions and glacier retreat have resulted in disconnection of tributary

  5. Glaciers, Glacial lakes and Glacial Lake Outburst Floods in the Koshi Basin

    NASA Astrophysics Data System (ADS)

    Shrestha, F.; Gao, X.; Khanal, N. R.; Maharjan, S. B.; Bajracharya, S. R.; Shrestha, R. B.; Lizong, W.; Mool, P. K.

    2016-12-01

    Glacier is a vital water resources for mountain communities. Recession in glacier area either increased the glacial lake size or develop a new lake. The consequences of these changes in lake has become one of the major issue in the management of GLOF risk. This paper presents the distribution of, and changes in, glaciers, glacial lakes in the Koshi basin and also looks at past GLOF events that have occurred in the basin and their distance of impact. Data on the number of glaciers and glacial lakes and their areas were generated for the years 1977, 1990, 2000, and 2010 using Landsat images. The study revealed that there were a total of 845 glaciers (Nepal side) and 2,168 glacial lakes (Nepal and China side) with a total area of 1,103 km2 and 127.608 km2 in 2010. The number of glacier increased by 15% (109) and area decreased by 26% (396 km2) over 33 years. In case of glacier lakes, the number and area increased from 1,160 to 2,168 and from 94.444 km2 to 127.608 km2 during 33 years with an overall growth rates of 86.9% and 35.1%. A large number of glacial lakes are small in size (≤ 0.1 km2). End moraine dammed lakes with area ≥ 0.1 km2 were selected to analyse the change characteristics of glacial lakes. The results show that there were 134 lakes ≥ 0.1 km2 in 2010; these lakes had a total area of 43.06 km2 in 1997, increased to 64.35 km2 in 2010. The distribution of lakes on the north side of the Himalayas (in China) was three times higher than on the south side of the Himalayas (in Nepal). Comparing the mean growth rate in area and length for the 33 years, the growth rate on the north side was found to be a little slower than that on the south side. This relationship did not hold true for length change in the different periods. The study identified 42 rapidly growing large lakes that are dangerous in terms of GLOF risk. In the past, 18 GLOF events have been reported. The downstream distance impacted by those events was up to 90 km. Among them, 13 GLOF events

  6. The role of melting alpine glaciers in mercury export and transport: An intensive sampling campaign in the Qugaqie Basin, inland Tibetan Plateau.

    PubMed

    Sun, Xuejun; Wang, Kang; Kang, Shichang; Guo, Junming; Zhang, Guoshuai; Huang, Jie; Cong, Zhiyuan; Sun, Shiwei; Zhang, Qianggong

    2017-01-01

    Glaciers, particularly alpine glaciers, have been receding globally at an accelerated rate in recent decades. The glacial melt-induced release of pollutants (e.g., mercury) and its potential impact on the atmosphere and glacier-fed ecosystems has drawn increasing concerns. During 15th-20th August, 2011, an intensive sampling campaign was conducted in Qugaqie Basin (QB), a typical high mountain glacierized catchment in the inland Tibetan Plateau, to investigate the export and transport of mercury from glacier to runoff. The total mercury (THg) level in Zhadang (ZD) glacier ranged from <1 to 20.8 ng L -1 , and was slightly higher than levels measured in glacier melt water and the glacier-fed river. Particulate Hg (PHg) was the predominant form of Hg in all sampled environmental matrices. Mercury concentration in Qugaqie River (QR) was characterized by a clear diurnal variation which is linked to glacier melt. The estimated annual Hg exports by ZD glacier, the upper river basin and the entire QB were 8.76, 7.3 and 157.85 g, respectively, with respective yields of 4.61, 0.99 and 2.74 μg m -2  yr -1 . Unique landforms and significant gradients from the glacier terminus to QB estuary might promote weathering and erosion, thereby controlling the transport of total suspended particulates (TSP) and PHg. In comparison with other glacier-fed rivers, QB has a small Hg export yet remarkably high Hg yield, underlining the significant impact of melting alpine glaciers on regional Hg biogeochemical cycles. Such impacts are expected to be enhanced in high altitude regions under the changing climate. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. The role of melting alpine glaciers in mercury export and transport: an intensive sampling campaign in the Qugaqie Basin, inland Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Sun, X.; Zhang, Q.

    2016-12-01

    Glaciers, particularly alpine glaciers, have been receding globally at an accelerated rate in recent decades. The glacial melt-induced release of pollutants (e.g., mercury) and its potential impact on the atmosphere and glacier-fed ecosystems has drawn increasing concerns. During 15th to 20th August, 2011, an intensive sampling campaign was conducted in Qugaqie Basin (QB), a typical high mountain glacierized catchment in the inland Tibetan Plateau, to investigate the export and transport of mercury from glacier to runoff. The total mercury (THg) level in Zhadang (ZD) glacier ranged from < 1 to 20.8 ng L-1, and was slightly higher than levels measured in glacier melt water and the glacier-fed river. Particulate Hg (PHg) was the predominant form of Hg in all sampled environmental matrices. Mercury concentration in Qugaqie River (QR) was characterized by a clear diurnal variation which is linked to glacier melt. The estimated annual Hg exports by ZD glacier, the upper river basin and the entire QB were 8.76, 7.3 and 157.85 g, respectively, with respective yields of 4.61, 0.99 and 2.74 μg m-2 yr-1. Unique landforms and significant gradients from the glacier terminus to QB estuary might promote weathering and erosion, thereby controlling the transport of total suspended particulates (TSP) and PHg. In comparison with other glacier-fed rivers, QB has a small Hg export yet remarkably high Hg yield, underlining the significant impact of melting alpine glaciers on regional Hg biogeochemical cycles. Such impacts are expected to be enhanced in high altitude regions under the changing climate.

  8. Glacier mass budget measurements by hydrologic means

    USGS Publications Warehouse

    Tangborn, Wendell V.

    1966-01-01

    Ice storage changes for the South Cascade Glacier drainage basin were determined for the 1957–1964 period using basin runoff and precipitation measurements. Measurements indicate that evaporation and condensation are negligible compared with the large runoff and precipitation values. Runoff, measured by a stream discharge station, averaged 4.04 m/yr; precipitation, determined by snow accumulation measurements at a central point on the glacier and by storage gages, averaged 3.82 m/yr, resulting in a basin net loss of about 0.22 m/yr. During the same period, South Cascade Glacier net budgets were determined by ablation stakes, snow density-depth profiles, and maps. The average glacier net budget for the period was −0.61sol;yr of water. This amount is equivalent to −0.26 m of water when averaged over the drainage basin (43% glacier-covered), which is in fair agreement with the net storage change measured by hydrologic methods. Agreement between the two methods for individual years is slightly less perfect.

  9. Energy balance-based distributed modeling of snow and glacier melt runoff for the Hunza river basin in the Pakistan Karakoram Himalayan region

    NASA Astrophysics Data System (ADS)

    Shrestha, M.; Wang, L.; Koike, T.; Xue, Y.; Hirabayashi, Y.; Ahmad, S.

    2012-12-01

    A spatially distributed biosphere hydrological model with energy balance-based multilayer snow physics and multilayer glacier model, including debris free and debris covered surface (enhanced WEB-DHM-S) has been developed and applied to the Hunza river basin in the Pakistan Karakoram Himalayan region, where about 34% of the basin area is covered by glaciers. The spatial distribution of seasonal snow and glacier cover, snow and glacier melt runoff along with rainfall-contributed runoff, and glacier mass balances are simulated. The simulations are carried out at hourly time steps and at 1-km spatial resolution for the two hydrological years (2002-2003) with the use of APHRODITE precipitation dataset, observed temperature, and other atmospheric forcing variables from the Global Land Data Assimilation System (GLDAS). The pixel-to-pixel comparisons for the snow-free and snow-covered grids over the region reveal that the simulation agrees well with the Moderate Resolution Imaging Spectroradiometer (MODIS) eight-day maximum snow-cover extent data (MOD10A2) with an accuracy of 83% and a positive bias of 2.8 %. The quantitative evaluation also shows that the model is able to reproduce the river discharge satisfactorily with Nash efficiency of 0.92. It is found that the contribution of rainfall to total streamflow is small (about 10-12%) while the contribution of snow and glacier is considerably large (35-40% for snowmelt and 50-53% for glaciermelt, respectively). The model simulates the state of snow and glaciers at each model grid prognostically and thus can estimate the net annual mass balance. The net mass balance varies from -2 m to +2 m water equivalent. Additionally, the hypsography analysis for the equilibrium line altitude (ELA) suggests that the average ELA in this region is about 5700 m with substantial variation from glacier to glacier and region to region. This study is the first to adopt a distributed biosphere hydrological model with the energy balance- based

  10. Temporal fluctuations and frontal area change of Bangni and Dunagiri glaciers from 1962 to 2013, Dhauliganga Basin, central Himalaya, India

    NASA Astrophysics Data System (ADS)

    Kumar, Vinit; Mehta, Manish; Mishra, Ajai; Trivedi, Anjali

    2017-05-01

    Glaciers have been receding for the last 100 years in many glaciated regions of the world, and the rate of recession has accelerated during the last 60 years. Recent assessments of changes in glaciers in the Himalaya have usually recognized their variable rate of recession. The present study deals with snout retreat, frontal area vacation, and estimation of the equilibrium line altitude (ELA) of Bangni and Dunagiri glaciers, in the Dhauliganga Basin, central Himalaya (India), using multi-image satellite data (Landsat MSS, 1976; Landsat TM, 1990; Landsat ETM +, 2005) and Survey of India topographic maps (1962; 1:50,000) along with field surveys (2012 to 2014) for the period of 1962-2013. The meteorological data of the India Meteorological Department (IMD) and TRMM suggested that the central Himalaya received less precipitation between 1960 and 1990. Because of the less precipitation, glaciers receded rapidly during this period. The present study shows that Bangni and Dunagiri glaciers retreated 2080 ± 162 m and 484 ± 38 m with average rates of 41 ± 3.2 m a- 1 and 9 ± 0.6 m a- 1 between 1962 and 2013, respectively. During this period Bangni and Dunagiri glaciers lost about 17% and 11% of their length, respectively. The result also suggested that Bangni Glacier vacated 598,948 ± 12,257 m2 frontal area, while Dunagiri Glacier vacated 170,428 ± 7833 m2 frontal area between 1962 and 2013. Moreover, the estimated ELA change for Bangni Glacier was 64 ± 30 m upward during the study period. The Geological Survey of India (GSI, 1998a,b) suggested that the ELA of Dunagiri Glacier rose 28 m between 1984 and 1992 and that the glacier lost (-)16 × 106 m3 w.e. ice with an average rate of loss of (-)1.04 m w.e. a- 1. The geomorphology of the Dunagiri Valley reflected that Bangni and Dunagiri glaciers were joined together in the past. Nevertheless, these two glaciers retreat at different rates, indicating that climate change is not the only factor in glacier retreat but that

  11. Rapid changes in glacier surface processes and downstream river basin in the Central Himalayan region

    NASA Astrophysics Data System (ADS)

    Haritashya, U. K.; Strattman, K.; Kargel, J. S.

    2017-12-01

    A high altitude glacierized region in the central Himalaya hosts thousands of glaciers and originates major rivers like the Ganges and Yamuna. This region has seen significant changes in last few decades due to climate system coupling involving the westerlies and the monsoon, high seismic activities, complex topography, extensive glacier debris cover, and widespread mass movement. Consequently, we analyzed regional variability in hundreds of glacier surface processes and downstream river basins of varying geomorphology using a variety of satellite imagery from the early 1990s to 2017. Our results indicate a massive increase in supraglacial ponds in south facing glaciers. Several of these ponds are either seasonal and forms exactly at the same location every year or forms at the beginning of the melt season and drains out as the season progresses from April to July/August. We also observed evolution in size of these ponds in the last two decades to the point where some of them now seem to be stationary and might increase in size and develop large lake in the future. To understand our result and melting pattern in the region, we also analyzed ice velocity and surface temperature; both of which reveals a temporal shift in the pattern. Glacier surface temperatures, especially show a warming pattern in recent years and strong correlation with debris cover. Additionally, we also observed changes in the downstream region both around the river bed and steep slopes where massive erosion of Himalayan glaciers are depositing and transporting excessive amount of sediments. Overall, our results are discussed in the context of better landscape evolution modeling from the top of the glacier to the several km downstream from the glacier terminus.

  12. Rapid Expansion of Glacial Lakes Caused by Climate and Glacier Retreat in the Central Himalayas

    NASA Astrophysics Data System (ADS)

    Wang, W.

    2016-12-01

    Glacial lake outburst floods are among the most serious natural hazards in the Himalayas. Such floods are of high scientific and political importance because they exert trans-boundary impacts on bordering countries. The preparation of an updated inventory of glacial lakes and the analysis of their evolution are an important first step in assessment of hazards from glacial lake outbursts. Here, we report the spatiotemporal developments of the glacial lakes in the Poiqu River basin, a trans-boundary basin in the Central Himalayas, from 1976 to 2010 based on multi-temporal Landsat images. Studied glacial lakes are classified as glacierfed lakes and non-glacier-fed lakes according to their hydrologic connection to glacial watersheds. A total of 119 glacial lakes larger than 0.01 km2 with an overall surface area of 20.22 km2 (±10.8%) were mapped in 2010, with glacier-fed lakes being predominant in both number (69, 58.0%) and area (16.22 km2, 80.2%). We found that lakes connected to glacial watersheds (glacier-fed lakes) significantly expanded (122.1%) from 1976 to 2010, whereas lakes not connected to glacial watersheds (non-glacier-fed lakes) remained stable (+2.8%) during the same period. This contrast can be attributed to the impact of glaciers. Retreating glaciers not only supply meltwater to lakes but also leave space for them to expand. Compared with other regions of the Hindu Kush Himalayas (HKH), the lake area per glacier area in the Poiqu River basin was the highest. This observation might be attributed to the different climate regimes and glacier status along the HKH. The results presented in this study confirm the significant role of glacier retreat on the evolution of glacial lakes.

  13. Glacier Erosion and Response to Climate in Chilean Patagonia

    NASA Astrophysics Data System (ADS)

    Koppes, M.; Hallet, B.; Stewart, R.

    2006-12-01

    A vibrant dimension in current research on landscape evolution is the potential impact of climate change on erosion rates due to differences in efficiency of glacial and non-glacial erosion processes. The climate-sensitive rate and spatial distribution of erosion can be as important as the tectonic environment in determining the development of mountain ranges. To evaluate properly how glacial erosion influences orogenic processes and reflects climate variability, it is necessary to understand how ice dynamics control erosion rates. The Patagonian Andes are a unique laboratory for documenting glacial erosion in a range of precipitation and thermal regimes, as zonal atmospheric circulation in the region creates strong latitudinal gradients. We will present relevant findings from two tidewater glaciers in Chilean Patagonia: San Rafael glacier, which drains the northern portion of the North Patagonian Icefield (46.6S, 74W), and Marinelli glacier, the largest glacier in the Cordillera Darwin of Tierra del Fuego (54.6S, 69W). Both glaciers have been in steady retreat during the latter half of the 20th century, and both calve into a fjord or lagoon, which provides an efficient trap for the sediment eroded by the glacier and deposited at the calving front. The reconstructed flux of ice into the glaciers is compared to the retreat of the ice fronts and to the sediment flux to examine the influence of ice dynamics on the rate of glacier erosion. NCEP-NCAR Reanalysis climate data, adjusted to local conditions by correlation with automatic weather stations installed at the glacier termini and coupled to a model of orographic enhancement of precipitation over the glacier basin, were used to reconstruct the daily precipitation input into and ablation output from the glaciers during the last 50 years. The sediment flux out of the glaciers during this period was calculated from acoustic reflection profiles of the sediments accumulated in the proglacial fjords, and used to infer

  14. Glacier and snow hydrology investigation in the Upper Indus Basin using Synthetic Aperture Radar

    NASA Astrophysics Data System (ADS)

    Jouvet, G.; Stastny, T.; Oettershagen, P.; Hugentobler, M.; Mantel, T.; Melzer, A.; Weidmann, Y.; Funk, M.; Siegwart, R.; Lund, J.; Forster, R. R.; Burgess, E. W.

    2017-12-01

    The flows of the Indus River are a vital resource for food security, ecosystem services, hydropower and economy for China, India and Pakistan. Glaciers of the Karakoram Mountains are the largest drivers of discharge in the Upper Indus Basin, and combined with snowmelt constitute the majority of runoff. While recently verified in near balance, the glaciers of the Karakoram exhibit substantial variation both spatially and temporally. Complex climatology, coupled with the challenges of field study in this rugged range, illicit notable uncertainties in observation and prediction of glacial status. Satellite-borne radar sensors acquire imagery regardless of cloud cover or time of day, and offer unique insights into physical processes due to their wavelength. Here we utilize Sentinel-1 synthetic aperture radar (SAR) imagery to track transient snow lines on glaciers of the Shigar watershed throughout multiple ablation seasons, and discuss the utility of this information in relation to snow and glacier mass balance. As the Sentinel-1 sensor ascending and descending passes capture morning and evening imagery in this region, diurnal radar variations will also be explored as indicators of melt-refreeze cycles and their correlation with peak runoff.

  15. Contrasting evolution patterns between glacier-fed and non-glacier-fed lakes in the central Tibetan Plateau and driving force analysis

    NASA Astrophysics Data System (ADS)

    Song, C.; Sheng, Y.

    2015-12-01

    High-altitude lakes in the Tibetan Plateau (TP) showed strong spatio-temporal variability during past decades. The lake dynamics can be associated with several key factors including lake type, supply of glacial meltwater, local climate variations. It is important to differentiate these factors when analyzing the driving force of lakes dynamics. With a focus on lakes over the Tanggula Mountains of the central TP, this study investigates the temporal evolution patterns of lake area and water level of different types: glacier-fed closed lake, non-glacier-fed closed lake and upstream lake (draining into closed lakes). We collected all available Landsat archive data and quantified the inter-annual variability of lake extents. Results show accelerated expansions of both glacier-fed and non-glacier-fed lakes during 1970s-2013, and different temporal patterns of the two types of lakes: the non-glacier-fed lakes displayed a batch-wise growth pattern, with obvious growth in 2002, 2005 and 2011 and slight changes in other years, while glacier-fed lakes showed steady expanding tendency. The contrasting patterns are confirmed by the distinction of lake level change between the two groups derived from satellite altimetry during 2003-2009. The upstream lakes remained largely stable due to natural drainage regulation. The intermittent expansions for non-glacier-fed lakes were found to be related to excessive precipitation events and positive "precipitation-evaporation". In contrast, glacier-fed lake changes showed weak correlations with precipitation variations, which imply a joint contribution from glacial meltwater to water budgets. A simple estimation reveals that the increased water storage for all of examined lakes contributed from precipitation/evaporation (0.31±0.09 Gt/yr) slightly overweighed the glacial meltwater supply (0.26±0.08 Gt/yr).

  16. Tsivat Basin conduit system persists through two surges, Bering Piedmont Glacier, Alaska

    USGS Publications Warehouse

    Fleisher, P.J.; Cadwell, D.H.; Muller, E.H.

    1998-01-01

    The 1993-1995 surge of Bering Glacier, Alaska, occurred in two distinct phases. Phase 1 of the surge began on the eastern sector in July, 1993 and ended in July, 1994 after a powerful outburst of subglacial meltwater into Tsivat Lake basin on the north side of Weeping Peat Island. Within days, jokulhlaup discharge built a 1.5 km2 delta of ice blocks (25-30 m) buried in outwash. By late October 1994, discharge temporarily shifted to a vent on Weeping Peat Island, where a second smaller outburst dissected the island and built two new sandar. During phase 2, which began in spring 1995 and ended within five months, continuous discharge issued from several vents along the ice front on Weeping Peat Island before returining to the Tsivat Basin. Surge related changes include a five- to six-fold increase in meltwater turbidity; the redirection of supercooled water in two ice-contact lakes; and an increase in the rate of glaciolacustrine sedimentation. US Geological Survey aerial photos by Austin Post show large ice blocks in braided channels indicating excessive subglacial discharge in a similar position adjacent to Weeping Peat Island during the 1966-1967 surge. During the subsequent three decades of retreat, the location of ice-marginal, subglacial discharge vents remained aligned on a linear trend that describes the position of a persistent subglacial conduit system. The presence of a major conduit system, possibly stabilized by subglacial bedrock topography, is suggested by: 1) high-level subglacial meltwater venting along the northern side of Weeping Peat Island during the 1966-1967 surge, 2) persistent low-level discharge between surges, and 3) the recurrence of localizing meltwater outbursts associated with both phases of the 1993-1005 surge.

  17. Water, Ice, and Meteorological Measurements at South Cascade Glacier, Washington, Balance Years 2004 and 2005

    USGS Publications Warehouse

    Bidlake, William R.; Josberger, Edward G.; Savoca, Mark E.

    2007-01-01

    Winter snow accumulation and summer snow and ice ablation were measured at South Cascade Glacier, Washington, to estimate glacier mass-balance quantities for balance years 2004 and 2005. The North Cascade Range in the vicinity of South Cascade Glacier accumulated smaller than normal winter snowpacks during water years 2004 and 2005. Correspondingly, the balance years 2004 and 2005 maximum winter snow balances of South Cascade Glacier, 2.08 and 1.97 meters water equivalent, respectively, were smaller than the average of such balances since 1959. The 2004 glacier summer balance (-3.73 meters water equivalent) was the eleventh most negative during 1959 to 2005 and the 2005 glacier summer balance (-4.42 meters water equivalent) was the third most negative. The relatively small winter snow balances and unusually negative summer balances of 2004 and 2005 led to an overall loss of glacier mass. The 2004 and 2005 glacier net balances, -1.65 and -2.45 meters water equivalent, respectively, were the seventh and second most negative during 1953 to 2005. For both balance years, the accumulation area ratio was less than 0.05 and the equilibrium line altitude was higher than the glacier. The unusually negative 2004 and 2005 glacier net balances, combined with a negative balance previously reported for 2003, resulted in a cumulative 3-year net balance of -6.20 meters water equivalent. No equal or greater 3-year mass loss has occurred previously during the more than 4 decades of U.S. Geological Survey mass-balance measurements at South Cascade Glacier. Accompanying the glacier mass losses were retreat of the terminus and reduction of total glacier area. The terminus retreated at a rate of about 17 meters per year during balance year 2004 and 15 meters per year during balance year 2005. Glacier area near the end of balance years 2004 and 2005 was 1.82 and 1.75 square kilometers, respectively. Runoff from the basin containing the glacier and from an adjacent nonglacierized basin was

  18. Methods for Automating Analysis of Glacier Morphology for Regional Modelling: Centerlines, Extensions, and Elevation Bands

    NASA Astrophysics Data System (ADS)

    Viger, R. J.; Van Beusekom, A. E.

    2016-12-01

    The treatment of glaciers in modeling requires information about their shape and extent. This presentation discusses new methods and their application in a new glacier-capable variant of the USGS PRMS model, a physically-based, spatially distributed daily time-step model designed to simulate the runoff and evolution of glaciers through time. In addition to developing parameters describing PRMS land surfaces (hydrologic response units, HRUs), several of the analyses and products are likely of interest to cryospheric science community in general. The first method is a (fully automated) variation of logic previously presented in the literature for definition of the glacier centerline. Given that the surface of a glacier might be convex, using traditional topographic analyses based on a DEM to trace a path down the glacier is not reliable. Instead a path is derived based on a cost function. Although only a single path is presented in our results, the method can be easily modified to delineate a branched network of centerlines for each glacier. The second method extends the glacier terminus downslope by an arbitrary distance, according to local surface topography. This product is can be used to explore possible, if unlikely, scenarios under which glacier area grows. More usefully, this method can be used to approximate glacier extents from previous years without needing historical imagery. The final method presents an approach for segmenting the glacier into altitude-based HRUs. Successful integration of this information with traditional approaches for discretizing the non-glacierized portions of a basin requires several additional steps. These include synthesizing the glacier centerline network with one developed with a traditional DEM analysis, ensuring that flow can be routed under and beyond glaciers to a basin outlet. Results are presented based on analysis of the Copper River Basin, Alaska.

  19. Glaciers and small ice caps in the macro-scale hydrological cycle - an assessment of present conditions and future changes

    NASA Astrophysics Data System (ADS)

    Lammers, Richard; Hock, Regine; Prusevich, Alexander; Bliss, Andrew; Radic, Valentina; Glidden, Stanley; Grogan, Danielle; Frolking, Steve

    2014-05-01

    Glacier and small ice cap melt water contributions to the global hydrologic cycle are an important component of human water supply and for sea level rise. This melt water is used in many arid and semi-arid parts of the world for direct human consumption as well as indirect consumption by irrigation for crops, serving as frozen reservoirs of water that supplement runoff during warm and dry periods of summer when it is needed the most. Additionally, this melt water reaching the oceans represents a direct input to sea level rise and therefore accurate estimates of this contribution have profound economic and geopolitical implications. It has been demonstrated that, on the scale of glacierized river catchments, land surface hydrological models can successfully simulate glacier contribution to streamflow. However, at global scales, the implementation of glacier melt in hydrological models has been rudimentary or non-existent. In this study, a global glacier mass balance model is coupled with the University of New Hampshire Water Balance/Transport Model (WBM) to assess recent and projected future glacier contributions to the hydrological cycle over the global land surface (excluding the ice sheets of Greenland and Antarctica). For instance, results of WBM simulations indicate that seasonal glacier melt water in many arid climate watersheds comprises 40 % or more of their discharge. Implicitly coupled glacier and WBM models compute monthly glacier mass changes and resulting runoff at the glacier terminus for each individual glacier from the globally complete Randolph Glacier Inventory including over 200 000 glaciers. The time series of glacier runoff is aggregated over each hydrological modeling unit and delivered to the hydrological model for routing downstream and mixing with non-glacial contribution of runoff to each drainage basin outlet. WBM tracks and uses glacial and non-glacial components of the in-stream water for filling reservoirs, transfers of water between

  20. Glacier fluctuations in the Kenai Fjords, Alaska, U.S.A.: An evaluation of controls on Iceberg-calving glaciers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wiles, G.C.; Calkin, P.E.; Post, A.

    The histories of four iceberg-calving outlet-glacier systems in the Kenai Fjords National Park underscore the importance of fiord depth, sediment supply, and fiord geometry on glacier stability. These parameters, in turn, limit the reliability of calving glacier chronologies as records of climatic change. Tree-ring analysis together with radiocarbon dating show that the Northwestern and McCarty glaciers, with large drainage basins, were advancing in concert with nearby land-terminating glaciers about A.D. 600. After an interval of retreat and possible nonclimatically induced extension during the Medieval Warm Period, these ice margins advanced again through the Little Ice Age and then retreated synchronouslymore » with the surrounding land-terminating glaciers about A.D. 1900. In contrast, Holgate and Aialik glaciers, with deeper fiords and smaller basins, retreated about 300 yr earlier. Reconstructions of Little Ice Age glaciers suggest that equilibrium-line altitudes of Northwestern and McCarty glaciers were, respectively, 270 and 500 m lower than now. Furthermore, the reconstructions show that these two glaciers were climatically sensitive when at their terminal moranies. However, with ice margins at their present recessional positions and accumulation area ratios between 0.8 and 0.9, only McCarty Glacier shows evidence of advance. Aialik and Holgate glaciers were climatically insensitive during the Little Ice Age maxima and remain insensitive to climate. 40 refs., 7 figs., 2 tabs.« less

  1. A subaquatic moraine complex in overdeepened Lake Thun (Switzerland) unravelling the deglaciation history of the Aare Glacier

    NASA Astrophysics Data System (ADS)

    Fabbri, S. C.; Buechi, M. W.; Horstmeyer, H.; Hilbe, M.; Hübscher, C.; Schmelzbach, C.; Weiss, B.; Anselmetti, F. S.

    2018-05-01

    To investigate the history of the Aare Glacier and its overdeepened valley, a high-resolution multibeam bathymetric dataset and a 2D multi-channel reflection seismic dataset were acquired on perialpine Lake Thun (Switzerland). The overdeepened basin was formed by a combination of tectonically predefined weak zones and glacial erosion during several glacial cycles. In the deepest region of the basin, top of bedrock lies at ∼200 m below sea level, implying more than 750 m of overdeepening with respect to the current fluvial base level (i.e. lake level). Seismic stratigraphic analysis reveals the evolution of the basin and indicates a subaquatic moraine complex marked by high-amplitude reflections below the outermost edge of a morphologically distinct platform in the southeastern part of the lake. This stack of seven subaquatic terminal moraine crests was created by a fluctuating, "quasi-stagnant" grounded Aare Glacier during its overall recessional phase. Single packages of overridden moraine crests are seismically distuinguishable, which show a transition downstream into prograding clinoforms with foresets at the ice-distal slope. The succession of subaquatic glacial sequences (foresets and adjacent bottomsets) represent one fifth of the entire sedimentary thickness. Exact time constraints concerning the deglacial history of the Aare Glacier are very sparse. However, existing 10Be exposure ages from the accumulation area of the Aare Glacier and radiocarbon ages from a Late-Glacial lake close to the outlet of Lake Thun indicate that the formation of the subaquatic moraine complex and the associated sedimentary infill must have occurred in less than 1000 years, implying high sedimentation rates and rapid disintegration of the glacier. These new data improve our comprehension of the landforms associated with the ice-contact zone in water, the facies architecture of the sub- to proglacial units, the related depositional processes, and thus the retreat mechanisms of

  2. Dynamic Change in Glacial Dammed Lake Behavior of Suicide Basin, Mendenhall Glacier, Juneau Alaska

    NASA Astrophysics Data System (ADS)

    Jacobs, A. B.; Moran, T.; Hood, E. W.

    2016-12-01

    Suicide Basin Jökulhlaups, since 2011, have resulted in moderate flooding on the Mendenhall Lake and River in Juneau, AK. At this time, the USGS recorded peak streamflow of 20,000 cfs in 2014, the highest flows officially reported by the USGS which was attributed to a Suicide Basin glacial-dammed lake release. However, the USGS estimated a peak flow of 27,000 cfs in 1961 and we suspect this event is partially the result of a glacial dammed lake release. From 2011 to 2015, data indicates that yearly outburst from Suicide Basin were the norm; however, in 2015 and 2016, multiple outbursts during the summer were observed suggesting a dynamic change in glacial behavior. For public safety and awareness, the University of Alaska Southeast and U.S. Geologic Survey began monitoring real-time Suicide Basin lake levels. A real-time model was developed by the National Weather Service Alaska-Pacific River Forecast Center capable of forecasting potential timing and magnitude of the flood-wave crest from this Suicide Basin release. However, the model now is being modified because data not previously available has become available and adapted to the change in state of glacial behavior. The importance of forecasting time and level of crest on the Mendenhall River system owing to these outbursts floods is an essential aid to emergency managers and the general public to provide impact decision support services (IDSS). The National Weather Service has been able to provide 36 to 24 hour forecasts for these large events, but with the change in glacial state on the Mendenhall Glacier, the success of forecasting these events is getting more challenging. We will show the success of the hydrologic model but at the same time show the challenges we have seen with the changing glacier dynamics.

  3. Topographic context of glaciers and perennial snowfields, Glacier National Park, Montana

    NASA Astrophysics Data System (ADS)

    Allen, Thomas R.

    1998-01-01

    Equilibrium-line altitudes (ELAs) of modem glaciers in the northern Rocky Mountains are known to correspond with regional climate, but strong subregional gradients such as across the Continental Divide in Glacier National Park, Montana, also exert topoclimatic influences on the ELA. This study analyzed the relationships between glacier and snowfield morphology, ELA, and surrounding topography. Glaciers and perennial snowfields were mapped using multitemporal satellite data from the Landsat Thematic Mapper and aerial photography within an integrated Geographic Information System (GIS). Relationships between glacier morphology and ELA were investigated using discriminant analysis. Four morphological categories of perennial snow and ice patches were identified: cirque glacier, niche glacier, ice cap, and snowfield. ELA was derived from overlaid glacier boundaries and Digital Elevation Models (DEMs) within the GIs. DEMs provided topographic variables and models of solar radiation and wind exposure/shelteredness. Regression analysis showed the effects of exposure; on snow accumulation, the strong influence of local topography through upslope zone morphology such as cirque backwalls, and the tendency for glaciers with high ELAs to exhibit compactness in morphology. Results highlight the relatively compact shape and larger area of glaciers adjacent to the Continental Divide. Discriminant analysis correctly predicted the type of glacier morphology in more than half the observations using factored variables of glacier shape, elevation range, and upslope area.

  4. Contribution potential of glaciers to water availability in different climate regimes

    PubMed Central

    Kaser, Georg; Großhauser, Martin; Marzeion, Ben

    2010-01-01

    Although reliable figures are often missing, considerable detrimental changes due to shrinking glaciers are universally expected for water availability in river systems under the influence of ongoing global climate change. We estimate the contribution potential of seasonally delayed glacier melt water to total water availability in large river systems. We find that the seasonally delayed glacier contribution is largest where rivers enter seasonally arid regions and negligible in the lowlands of river basins governed by monsoon climates. By comparing monthly glacier melt contributions with population densities in different altitude bands within each river basin, we demonstrate that strong human dependence on glacier melt is not collocated with highest population densities in most basins. PMID:21059938

  5. Response of Glacier and Lake Dynamics in Four Inland Basins to Climate Change at the Transition Zone between the Karakorum And Himalayas.

    PubMed

    Li, Zhiguo; Fan, Kuangsheng; Tian, Lide; Shi, Benlin; Zhang, Shuhong; Zhang, Jingjing

    2015-01-01

    Inland glacier and lake dynamics on the Tibetan Plateau (TP) and its surroundings over recent decades are good indicators of climate change and have a significant impact on the local water supply and ecosystem. The glacier and lake changes in Karakoram are quite different from those of the Himalayas. The mechanisms of the complex and regionally heterogeneous behavior of the glacier and lake changes between the Karakorum and Himalayas are poorly understood. Based on satellite images and meteorological data of Shiquanhe, Hetian, and Yutian stations, we demonstrate that the overall retreat of glaciers and increase of lake area at the transition zone between the Karakoram and Himalayas (TKH) have occurred since 1968 in response to a significant global climate change. Glacial areas in the Songmuxi Co basin, Zepu Co basin, Mang Co basin and Unnamed Co decreased by -1.98 ± 0.02 km2, -5.39 ± 0.02 km2, -0.01 ± 0.02 km2, and -0.12 ± 0.02 km2 during the study period, corresponding to losses of -1.42%, -2.86%, -1.54%, and -1.57%, respectively. The lake area of the Songmuxi Co, Zepu Co, Mang Co and Unnamed Co increased by 7.57 ± 0.02 km2, 8.53 ± 0.02 km2, 1.35 ± 0.02 km2, and 0.53 ± 0.02 km2, corresponding to growths of 30.22%, 7.55%, 11.39%, and 8.05%, respectively. Increases in temperature was the main reason for glacier retreat, whereas decreases in potential evapotranspiration of lakes, increases in precipitation, and increases in melt water from glaciers and frozen soil all contributed to lake area expansion.

  6. Response of Glacier and Lake Dynamics in Four Inland Basins to Climate Change at the Transition Zone between the Karakorum And Himalayas

    PubMed Central

    Li, Zhiguo; Fan, Kuangsheng; Tian, Lide; Shi, Benlin; Zhang, Shuhong; Zhang, Jingjing

    2015-01-01

    Inland glacier and lake dynamics on the Tibetan Plateau (TP) and its surroundings over recent decades are good indicators of climate change and have a significant impact on the local water supply and ecosystem. The glacier and lake changes in Karakoram are quite different from those of the Himalayas. The mechanisms of the complex and regionally heterogeneous behavior of the glacier and lake changes between the Karakorum and Himalayas are poorly understood. Based on satellite images and meteorological data of Shiquanhe, Hetian, and Yutian stations, we demonstrate that the overall retreat of glaciers and increase of lake area at the transition zone between the Karakoram and Himalayas (TKH) have occurred since 1968 in response to a significant global climate change. Glacial areas in the Songmuxi Co basin, Zepu Co basin, Mang Co basin and Unnamed Co decreased by -1.98 ± 0.02 km2, -5.39 ± 0.02 km2, -0.01 ± 0.02 km2, and -0.12 ± 0.02 km2 during the study period, corresponding to losses of -1.42%, -2.86%, -1.54%, and -1.57%, respectively. The lake area of the Songmuxi Co, Zepu Co, Mang Co and Unnamed Co increased by 7.57 ± 0.02 km2, 8.53 ± 0.02 km2, 1.35 ± 0.02 km2, and 0.53±0.02 km2, corresponding to growths of 30.22%, 7.55%, 11.39%, and 8.05%, respectively. Increases in temperature was the main reason for glacier retreat, whereas decreases in potential evapotranspiration of lakes, increases in precipitation, and increases in melt water from glaciers and frozen soil all contributed to lake area expansion. PMID:26699717

  7. Ice-proximal sediment dynamics and their effect on the stability of Muir Glacier, Alaska: A case study of non-climatic glacier response

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hunter, L.E.; Powell, R.D.

    1992-01-01

    Recent studies have shown that water depth at tidewater termini affect calving rates and, therefore, glacier mass balance and terminus stability. Grounding-line water depths are themselves governed by glacial and marine processes that interact during the formation of morainal bank depocenters. These morainal banks can fluctuate 10s of meters in height within an interval of a few weeks. Recent investigations in Glacier Bay have focused on quantitatively assessing sediment budgets in the ice-proximal environment. The monitoring of morainal banks in upper Muir Inlet has included repeated bathymetric mapping, sediment trap studies, bottom grab sampling, glacier and iceberg sampling, and submersiblemore » ROV investigations within 1 km of the terminus. Such relationships are important in interpreting recent changes in the dynamics of Muir Glacier where a century of retreat has been succeeded by quasi stability. The new glacier regime has accompanied basin infilling from approximately 100 m depth to a maximum of 52 m at the grounding line. Two large grounding-line fans have aggraded to deltas and reduced the length of the calving margin from 900 m to 290 m wide. These effects have reduced the ice flow velocities by 45%. Annual morainal bank growth ranged from 10[sup 6] to 10[sup 7] m[sup 3] and is the result of glacifluvial dumping, suspension settling from turbid overflow plumes, debris dumping from ice-cliff and iceberg melting, glacier squeezing and pushing of morainal bank sediment, and sediment gravity flow processes. Each of these processes are an integral facet of the morainal bank dynamics and glacier response. These studies of Muir Glacier indicate that glacier response to sediment dynamics need to be addresses before climatic implications are made.« less

  8. Geophysical observations on northern part of Georges Bank and adjacent basins of Gulf of Maine

    USGS Publications Warehouse

    Oldale, R.N.; Hathaway, J.C.; Dillon, William P.; Hendricks, J.D.; Robb, James M.

    1974-01-01

    Continuous-seismic-reflection and magnetic-intensity profiles provide data for inferences about the geology of the northern part of Georges Bank and the basins of the Gulf of Maine adjacent to the bank.Basement is inferred to be mostly sedimentary and volcanic rocks of Paleozoic age that were metamorphosed and intruded locally by felsic and mafic plutons near the end of the Paleozoic Era. During Late Triassic time, large fault basins formed within the Gulf of Maine and probably beneath Georges Bank. The fault basins and a possible major northeast-trending fault zone beneath the northern part of the bank probably formed as a result of the opening Atlantic during the Mesozoic. Nonmarine sediments, associated with mafic flows and intrusive rocks, were deposited in the fault basins as they formed. The upper surface of the Triassic and pre-Triassic rocks that comprise basement is an unconformity that makes up much of the bottom of the Gulf of Maine. Depth to the basement surface beneath the gulf differ greatly because of fluvial erosion in Tertiary time and glacial erosion in Pleistocene time. Beneath the northern part of Georges Bank the basement surface is smoother and slopes southward. Prominent valleys, cut before Late Cretaceous time, are present beneath this part of the bank.Cretaceous, Tertiary, and possibly Jurassic times were characterized by episodes of coastal-plain deposition and fluvial erosion. During this time a very thick wedge of sediment, mostly of Jurassic(?) and Cretaceous ages, was deposited on the shelf. Major periods of erosion took place at the close of the Cretaceous and during the Pliocene. Fluvial erosion during the Pliocene removed much of the coastal-plain sedimentary wedge and formed the Gulf of Maine.Pleistocene glaciers eroded all but a few remnants of the coastal-plain sediments within the gulf and deposited a thick section of drift against the north slope of Georges Bank and a thin veneer of outwash on the bank. Marine sediments were

  9. Glacier monitoring and glacier-climate interactions in the tropical Andes: A review

    NASA Astrophysics Data System (ADS)

    Veettil, Bijeesh Kozhikkodan; Wang, Shanshan; Florêncio de Souza, Sergio; Bremer, Ulisses Franz; Simões, Jefferson Cardia

    2017-08-01

    In this review, we summarized the evolution of glacier monitoring in the tropical Andes during the last few decades, particularly after the development of remote sensing and photogrammetry. Advantages and limitations of glacier mapping, applied so far, in Venezuela, Colombia, Ecuador, Peru and Bolivia are discussed in detail. Glacier parameters such as the equilibrium line altitude, snowline and mass balance were given special attention in understanding the complex cryosphere-climate interactions, particularly using remote sensing techniques. Glaciers in the inner and the outer tropics were considered separately based on the precipitation and temperature conditions within a new framework. The applicability of various methods to use glacier records to understand and reconstruct the tropical Andean climate between the Last Glacial Maximum (11,700 years ago) and the present is also explored in this paper. Results from various studies published recently were analyzed and we tried to understand the differences in the magnitudes of glacier responses towards the climatic perturbations in the inner tropics and the outer tropics. Inner tropical glaciers, particularly those in Venezuela and Colombia near the January Intertropical Convergence Zone (ITCZ), are more vulnerable to increase in temperature. Surface energy balance experiments show that outer tropical glaciers respond to precipitation variability very rapidly in comparison with the temperature variability, particularly when moving towards the subtropics. We also analyzed the gradients in glacier response to climate change from the Pacific coast towards the Amazon Basin as well as with the elevation. Based on the current trends synthesised from recent studies, it is hypothesized that the glaciers in the inner tropics and the southern wet outer tropics will disappear first as a response to global warming whereas glaciers in the northern wet outer tropics and dry outer tropics show resistance to warming trends due to

  10. Evolution of glacier-dammed lakes through space and time; Brady Glacier, Alaska, USA

    NASA Astrophysics Data System (ADS)

    Capps, Denny M.; Clague, John J.

    2014-04-01

    Glacier-dammed lakes and their associated jökulhlaups cause severe flooding in downstream areas and substantially influence glacier dynamics. Brady Glacier in southeast Alaska is well suited for a study of these phenomena because it presently dams 10 large (> 1 km2) lakes. Our objectives are to demonstrate how Brady Glacier and its lakes have co-evolved in the past and to apply this knowledge to predict how the glacier and its lakes will likely evolve in the future. To accomplish these objectives, we georeferenced a variety of maps, airphotos, and optical satellite imagery to characterize the evolution of the glacier and lakes. We also collected bathymetry data and created bathymetric maps of select lakes. Despite small advances and retreats, the main terminus of Brady Glacier has changed little since 1880. However, it downwasted at rates of 2-3 m/y between 1948 and 2000, more than the regional average. The most dramatic retreat (2 km) and downwasting (120 m) have occurred adjacent to glacier-dammed lakes and are primarily the result of calving. Brady Glacier is a former tidewater glacier. With continued downwasting, Brady Glacier may return to a tidewater regime and enter into a phase of catastrophic retreat. The situation at Brady Glacier is not unique, and the lessons learned here can be applied elsewhere to identify future glacier-dammed lakes, jökulhlaups, and glacier instability.

  11. Non-basin Mare Provinces on the Moon: The Roles of Primordial Rifting and Adjacent Basin Loading at Mare Frigoris and Mare Tranquillitatis.

    NASA Astrophysics Data System (ADS)

    McGovern, P. J., Jr.; Kramer, G. Y.; Neumann, G. A.

    2017-12-01

    In the last decade, new missions to the Moon have returned a flood of new high-resolution imaging, spectroscopy, topography, and gravity data that have triggered major advances in our knowledge of that body's origin, structure, and evolution. One major development is the identification of several large mare provinces (basalt-covered plains) that lack a clear association with the interiors of large impact basins. These include the broad but narrow Mare Frigoris (MF) north of the Imbrium and Serentiatis basins, and Mare Tranquillitatis (MT), which occupies the center of a triangular region delineated by the Crisium, Serenitatis, and Nectaris basins ("CSN Triangle"). MF and the western margin of MT coincide with the proposed volcano-tectonic (rift) boundary structures of the Procellarum region detected in the GRAIL gravity data, but a search for gravitational signals of basins revealed evidence for only one small basin in western MT and none in the remainder of MT or MF. These observations clearly show that the standard paradigm for creating maria, with basaltic melt ascending from an anomalously warm (and presumably impact-heated) mantle region beneath an impact basin to fill the basin, is insufficient to explain the Frigoris and Tranquillitatis mare units (and corresponding intrusives below). Alternative scenarios for mare unit emplacement include 1) volcanism generated from ancient Procellarum-bounding rift (PBR) structures, and 2) stress-enhanced magma ascent potential from central mare unit lithospheric loading in adjacent basins. The PBR scenario can in principle explain the emplacement of MF, but the concentric nature of the geometry of western and central MF with respect to Imbrium and eastern MF with respect to Serenitatis is then rendered coincidental. Some element of outer ring structure inheritance from these basins is suggested by the geometric relationships. The PBR scenario is also relevant to the western margin of Mare Tranquillitatis, where a strong

  12. Paleogeographic evolution of foldbelts adjacent to petroleum basins of Venezuela and Trinidad

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Goodman, E.D.; Koch, P.S.; Summa, L.L.

    1996-08-01

    The foldbelts of Venezuela and Trinidad have shaped the history of adjacent sedimentary basins. A set of paleogeographic maps on reconstructed bases depict the role of foldbelts in the development of the sedimentary basins of Venezuela. Some of the foldbelts are inverted, pre-Tertiary graben/passive margin systems. Other foldbelts are allochthonous nappes or parautochthons that override the Mesozoic passive margin hinge without inversion. The emergence of these foldbelts changed the course of existing river systems and provided a new source for sediments and maturation in adjacent deeps. The Merida Andes area was remobilized beginning in the Early Miocene as a zonemore » of lateral shear, along which the Bonaire Block has moved over 200 km to the northeast, dismembering the Maracaibo and Barinas basins. Late Miocene to Recent transpression and fault reactivation have driven rapid Andean uplift with thrust-related subsidence and maturation (e.g., SE Maracaibo foredeep). To the east, uplift and erosion of the Serrania del Interior (1) curtailed mid-Tertiary fluvial systems flowing northward from the igneous and sedimentary rocks of the Guyana Shield, deflecting them eastward, and (2) removed the thick early Miocene foredeep fill into a younger foredeep. Thus, the fold-thrust belts and sedimentary basins in this region are linked in their evolutionary histories.« less

  13. Arctic polynya and glacier interactions

    NASA Astrophysics Data System (ADS)

    Edwards, Laura

    2013-04-01

    Major uncertainties surround future estimates of sea level rise attributable to mass loss from the polar ice sheets and ice caps. Understanding changes across the Arctic is vital as major potential contributors to sea level, the Greenland Ice Sheet and the ice caps and glaciers of the Canadian Arctic archipelago, have experienced dramatic changes in recent times. Most ice mass loss is currently focused at a relatively small number of glacier catchments where ice acceleration, thinning and calving occurs at ocean margins. Research suggests that these tidewater glaciers accelerate and iceberg calving rates increase when warming ocean currents increase melt on the underside of floating glacier ice and when adjacent sea ice is removed causing a reduction in 'buttressing' back stress. Thus localised changes in ocean temperatures and in sea ice (extent and thickness) adjacent to major glacial catchments can impact hugely on the dynamics of, and hence mass lost from, terrestrial ice sheets and ice caps. Polynyas are areas of open water within sea ice which remain unfrozen for much of the year. They vary significantly in size (~3 km2 to > ~50,000 km2 in the Arctic), recurrence rates and duration. Despite their relatively small size, polynyas play a vital role in the heat balance of the polar oceans and strongly impact regional oceanography. Where polynyas develop adjacent to tidewater glaciers their influence on ocean circulation and water temperatures may play a major part in controlling subsurface ice melt rates by impacting on the water masses reaching the calving front. Areas of open water also play a significant role in controlling the potential of the atmosphere to carry moisture, as well as allowing heat exchange between the atmosphere and ocean, and so can influence accumulation on (and hence thickness of) glaciers and ice caps. Polynya presence and size also has implications for sea ice extent and therefore potentially the buttressing effect on neighbouring

  14. Assessing streamflow sensitivity to variations in glacier mass balance

    USGS Publications Warehouse

    O'Neel, Shad; Hood, Eran; Arendt, Anthony; Sass, Louis

    2014-01-01

    The purpose of this paper is to evaluate relationships among seasonal and annual glacier mass balances, glacier runoff and streamflow in two glacierized basins in different climate settings. We use long-term glacier mass balance and streamflow datasets from the United States Geological Survey (USGS) Alaska Benchmark Glacier Program to compare and contrast glacier-streamflow interactions in a maritime climate (Wolverine Glacier) with those in a continental climate (Gulkana Glacier). Our overall goal is to improve our understanding of how glacier mass balance processes impact streamflow, ultimately improving our conceptual understanding of the future evolution of glacier runoff in continental and maritime climates.

  15. Glaciation of alpine valleys: The glacier - debris-covered glacier - rock glacier continuum

    NASA Astrophysics Data System (ADS)

    Anderson, Robert S.; Anderson, Leif S.; Armstrong, William H.; Rossi, Matthew W.; Crump, Sarah E.

    2018-06-01

    because they are most common on lee sides of ridges and peaks where wind-blown snow enhances the strength of the avalanche source. To maintain positive mass balance, the avalanche cone developed in the winter must be sufficiently thick not to melt entirely in the summer, thus providing an ice accumulation area for the rock glacier. In the absence of rockfall, this would support a short cirque glacier. The presence of debris, however, facilitates the development of rock glaciers with lengths of hundreds of meters, thicknesses of tens of meters, and speeds of meters per year that are well described by numerical models. Numerical models are used to explore the alpine glacier response to its climate history. In warming climates, a debris-covered glacier can transform into a much shorter rock glacier, leaving in its wake a thinning ice-cored moraine. Rock glaciers will persist in landscapes well beyond debris-free counterparts because they have much longer response times to climate change. The headwaters of alpine basins with steep headwalls will therefore oscillate between glacier and rock glacier occupation over glacial-interglacial cycles, maintaining a means by which rock from the headwall can be conveyed away. This enhances the asymmetry of alpine ridgelines, with downwind valleys biting deeply into the range crests, as originally noted by G.K. Gilbert.

  16. The Importance of Glaciers as Thermal Buffers in the Kitsumkalum River Watershed, Coast Mountains, Canada

    NASA Astrophysics Data System (ADS)

    Beedle, M. J.; Menounos, B.; Biagi, M.; White, C.

    2016-12-01

    Glacier volume in the Coast Mountains of British Columbia is projected to decrease by up to 60% by the end of this century. The hydrologic impact of this change, however, is uncertain; these changes may negatively affect sport, commercial and subsistence fisheries dependent on Pacific salmon. To quantify hydrologic impacts of declining glacier cover, we commenced monitoring stream temperature and glacier change of the Kitsumkalum River basin, an important watershed for First Nations and sport fisheries. Our stream temperature sites include the main stem of the lower Kitsumkalum River, Kalum Lake and six sub-drainages with glacier cover that varied between 0.97-14.4%. Data for the 2016 hydrologic season reveal that maximum weekly average temperature (MWAT) ranged from 8.46 to 13.90 °C; more heavily glacierized basins maintained a lower MWAT than the less glacierized basins. Time series of MWAT indicate that temperatures of sub-basins in May differed by 1.11°C, presumably due to a similar pattern of snowmelt among the basins. By mid-July, MWAT values varied by 4.85 °C. Basins with less glacier cover (<1.24%) had their MWAT increase by an average of +6.96 ± 0.18 °C, while those with more glacier cover (5.29-14.4%) increased by an average of +2.80 ± 0.61 °C. If current conditions persist, it is probable that the lightly glacierized basins (<1.24%) will reach MWAT values exceeding the optimal range for salmon growth (12.8-14.8 °C). As glaciers of the Kitsumkalum watershed continue to recede in the coming decades, it is likely that all streams will approach temperatures less optimal for salmon growth, particularly during hot, dry summers. Glacierized watersheds, even with as little as 5% glacier cover, have significantly cooler stream temperatures than those with minimal (<1%) or no glacier cover. The thermal characteristics of streams in lightly-glacierized watersheds will change markedly in the coming decades. This change represents a near term impact from loss

  17. Integrated Optical and SAR Imagery with DEM to Quantify Glacier Water Storage Change in Upper Mekong River Basin

    NASA Astrophysics Data System (ADS)

    Liu, G. T.; Chen, J. B.; Le, T. S.; Chang, C. P.; Shum, C. K.; Tseng, K. H.

    2015-12-01

    In the past few decades, regional increase in air temperature has accelerated the ice melting in polar, sub-polar, and major land glacial areas. The glaciers in Tibetan Plateau, the largest glaciers outside Polar Regions and the sources of several trans-boundary major rivers, are now showing aggravated terminus retreat and thinning. The variation of freshwater availability is crucial for the economic development in Mainland Southeast Asia, especially in hydroelectric generation and agriculture irrigation. These rives, including the Mekong River, is also subject to upstream-downstream conflict and transboundary issues. In this study, we propose to estimate the remaining glacier water storage in Mekong River basin, and further analyze the impact of glacier retreat on these dams/reservoirs for the next decade. By calculating the Modified Normalized Difference Water Index (MNDWI), the water surface area (WSA) can thus be extracted from optical satellite images. On the other hand, the ice surface area (ISA) can be derived from the Polarimetric Synthetic Aperture Radar (POLSAR) images. With different polarization states of electromagnetic wave reflected by earth surface, POLSAR image can effectively identify glacier/ice from snow. Combined WSA and ISA information with digital elevation model (DEM), the change of freshwater storage in glaciers can be estimated. In the end, the influence on dams/reservoirs in the Mekong River caused by glacier retreat can be forecasted. The result can also be applied to hydrology, water allocation, and economy/agriculture policy determination.

  18. Medial moraines of glaciers of the Copper River Basin, Alaska: Discrete landslides dominate over other sources

    NASA Astrophysics Data System (ADS)

    Kargel, J. S.; Fischer, L.; Furfaro, R.; Huggel, C.; Korup, O.; Leonard, G. J.; Uhlmann, M.; Wessels, R. L.; Wolfe, D. F.

    2009-12-01

    Medial moraines are visually dominant structures of most large valley glaciers in the Copper River Basin (CRB), Alaska. Areally extensive but thin (usually <20 cm) accumulations of debris pose challenges for glacier mapping based on multispectral imagery, as done, for instance, in the GLIMS project. The sources of this material include large discrete landslides from wallrocks and from lateral moraines; diffuse contributions from rock falls and talus creep; rocks delivered via snow and ice avalanches; ingestion of lateral moraines along tributary convergences; and basal erosional debris. Evidence indicates that in CRB glaciers, discrete large avalanches predominate as the major contributors of moraine mass. Subglacial erosional debris is predominantly pulverized to small grain sizes and flushed. Many large, young avalanches exist on CRB glaciers. Evidence from colorimetry indicates that many medial moraines actually are landslides that have been sheared and swept downglacier, thus mimicking the form of other types of medial moraines formed where tributaries coalesce and flow down valley. Landcover classification of ASTER imagery, qualitative observations from air photos, and semiquantitative field-based estimations of rock color types indicate that on Allen Glacier, and other CRB glaciers, landslides are the sources of most medial moraines. On Allen and Root Glacier, for example, we see very few boulders with obvious signs of basal abrasion, whereas nearly all boulders exhibit signs of irregular fracture, for example in landslides. Such landslides have large effects on the thermal and mass balance of CRB glaciers, sometimes opposing or in other cases accentuating the effects of global/regional climate change. Considering the link between landslides and seismicity, and that Magnitude 8-9 earthquakes may occur nearby only about once a century, which is also the characteristic response time of large glaciers to climate shifts, seismicity must be considered along with

  19. Role of supraglacial lakes in recession of Himalayan glaciers: A case study of Dudh Koshi basin, Nepal

    NASA Astrophysics Data System (ADS)

    Tuladhar, Florencia Matina; KC, Diwakar

    2018-07-01

    Climate change has been adversely affecting glaciers causing them to advance and recession worldwide. Existing studies have primarily attributed temperature as the leading factor causing glacier recession. However, detailed studies that investigate effect of other factors like presence of debris cover, slope, and contact with water bodies are still scarce. This research, thus investigated the role of supraglacial lakes in recession of debris-covered glaciers (DCG). Such glaciers were studied since these lakes are found in debris-covered glaciers only. For this purpose the interannual variation in area of supraglacial lakes of Dudh Koshi basin was computed to test the hypothesis that these lakes play a significant role in glacier recession. Supraglacial lakes were delineated using Google Earth Pro at five year intervals to assess interannual variation in lake area. Slope, elevation and change in supraglacial lake area were the predictors influencing average decadal change in area of glaciers. Two models prepared using multiple linear regression in Excel were compared. The first model used elevation and slope as predictors while the second model used change in supraglacial lake area as the additional predictor. The second model had a higher coefficient of determination (R square) and Adjusted R-square values of 99 % and 96 % compared to the first model. Further test statistics from Analysis of Variance (ANOVA) results were compared to test the hypothesis. Moreover the Root mean square error (RMSE) of second model was also less than the first one. Hence both the regression statistics and RMSE confirmed that change in area of supraglacial lakes was an important factor that influences overall recession of debris-covered glaciers. Nevertheless, use of high spatial and temporal resolution imageries along-with increase in number of glaciers sampled should be incorporated in future studies to ensure robust outcomes. Thus this research can bolster the overall understanding

  20. Assessment of perception and adaptation to climate-related glacier changes in the arid Rivers Basin in northwestern China

    NASA Astrophysics Data System (ADS)

    Guofeng, Zhu; Dahe, Qin; Jiawen, Ren; Feng, Liang; Huali, Tong

    2017-06-01

    In many mountainous areas of the world, glaciers serve as a source of fresh water that is of critical importance and contributes to the sustainability of agriculture and other socio-economic activities. An enhanced understanding of socio-economic consequences of the climate-related glacier changes is essential to the identification of vulnerable entities and the development of well-targeted environmental adaptation policies. A questionnaire and interviews of farmers in the Heihe River Basin were used to analyze their perception of cryospheric changes, attitudes towards mitigation of cryospheric changes, and the ways in which they perceived their responsibility. Preferred responses and interventions for cryospheric change and views on responsible parties were also collected and evaluated. Our investigation revealed that most rural residents were concerned about glacier changes and believed they would bring harm to present society, individuals, and families, as well as to future generations. The respondents' perceptions were mainly influenced by the mass media. Most respondents tended to favor adaptation measures implemented by the government and other policy-making departments. An integrated approach will be needed to deal with the challenges to tackling climate-related glacier change.

  1. Preliminary bathymetry of Northwestern Fiord and Neoglacial changes of Northwestern Glacier

    USGS Publications Warehouse

    Post, Austin

    1980-01-01

    The first preliminary bathymetry (at 1:20,000 scale) and other scientific investigations of Northwestern Fiord, Alaska, were conducted by the Research Vessel Growler in 1978, disclosing this 10.5-mile-long branched waterway to be a deep basin enclosed by a terminal-moraine shoal. The basin was formerly filled by Northwestern Glacier, which began a drastic retreat around 1909 and reached the head of the main arm around 1960. Soundings and profiles show the main channel to be as much as 970 feet deep and to have the typical U shape of a severely glacially eroded valley; since the glacier 's retreat, sediments have formed nearly level deposits in the deepest reaches, while the rest of the basin has a hard, rocky bottom. Preneoglacial forest debris dated by carbon-14 indicates Northwestern Glacier to have advanced into the fiord prior to 1,385 years before present (B.P.); a branch glacier evidently advanced into forest 1,635 years B.P. The combined glaciers from several arms culminated on the present terminal-moraine shoal around 1894. (USGS)

  2. GlacierRocks - Glacier-Headwall Interaction and its Influence on Rockfall Activity

    NASA Astrophysics Data System (ADS)

    Hartmeyer, Ingo; Keuschnig, Markus; Krautblatter, Michael; Helfricht, Kay; Leith, Kerry; Otto, Jan-Christoph

    2017-04-01

    Climate models predict continued climate warming and a decrease of Austrian glaciers to less than 20% of their present area by the end of this century. Rockfall from freshly exposed headwalls has been documented as an increasing risk factor with considerable significance for man and high-alpine infrastructure. Recent findings of a five-year terrestrial laserscanning campaign (2011-2016) monitoring glacial headwalls at the Kitzsteinhorn (3.203 m a.s.l.), Hohe Tauern Range, Austria, show the dramatic impact of glacier thinning on adjacent headwalls: 80 % of the detected rockfall volumes were triggered from areas located less than 20 m above the current glacier surface. Despite these implications, little is known about the thermal, mechanical and hydrological processes that operate at the glacier-headwall interface (randkluft). Systemic in-situ monitoring of stability-relevant parameters are lacking, leaving fundamental gaps in the understanding of rockfall preconditioning in glacial headwalls and the geomorphological evolution of glaciated catchments. In this contribution we introduce the recently approved research project 'GlacierRocks', which starts in 2017 and will run for at least three years. 'GlacierRocks' will establish the worldwide first research site for long-term monitoring of stability-relevant processes inside a randkluft system. Based on the acquired monitoring data 'GlacierRocks' is pursuing three overall aims at (1) gaining a better understanding of rockfall preconditioning in randklufts and related geomorphological shaping of headwalls, (2) analyzing poorly understood glacial thinning dynamics near headwalls, and (3) estimating present and future rockfall hazard potential in headwalls on a regional scale. The three system components (headwall, glacier, randkluft) will be investigated by combining geomorphological, glaciological and meteorological methods. 'GlacierRocks' will continuously monitor rock temperature, rock moisture, frost cracking

  3. The contribution of glacier melt to streamflow

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schaner, Neil; Voisin, Nathalie; Nijssen, Bart

    2012-09-13

    Ongoing and projected future changes in glacier extent and water storage globally have lead to concerns about the implications for water supplies. However, the current magnitude of glacier contributions to river runoff is not well known, nor is the population at risk to future glacier changes. We estimate an upper bound on glacier melt contribution to seasonal streamflow by computing the energy balance of glaciers globally. Melt water quantities are computed as a fraction of total streamflow simulated using a hydrology model and the melt fraction is tracked down the stream network. In general, our estimates of the glacier meltmore » contribution to streamflow are lower than previously published values. Nonetheless, we find that globally an estimated 225 (36) million people live in river basins where maximum seasonal glacier melt contributes at least 10% (25%) of streamflow, mostly in the High Asia region.« less

  4. Delayed Acquisition of Non-Adjacent Vocalic Distributional Regularities

    ERIC Educational Resources Information Center

    Gonzalez-Gomez, Nayeli; Nazzi, Thierry

    2016-01-01

    The ability to compute non-adjacent regularities is key in the acquisition of a new language. In the domain of phonology/phonotactics, sensitivity to non-adjacent regularities between consonants has been found to appear between 7 and 10 months. The present study focuses on the emergence of a posterior-anterior (PA) bias, a regularity involving two…

  5. Glacial lakes amplify glacier recession in the central Himalaya

    NASA Astrophysics Data System (ADS)

    King, Owen; Quincey, Duncan; Carrivick, Jonathan; Rowan, Ann

    2016-04-01

    The high altitude and high latitude regions of the world are amongst those which react most intensely to climatic change. Across the Himalaya glacier mass balance is predominantly negative. The spatial and temporal complexity associated with this ice loss across different glacier clusters is poorly documented however, and our understanding of the processes driving change is limited. Here, we look at the spatial variability of glacier hypsometry and glacial mass loss from three catchments in the central Himalaya; the Dudh Koshi basin, Tama Koshi basin and an adjoining section of the Tibetan Plateau. ASTER and SETSM digital elevation models (2014/15), corrected for elevation dependant biases, co-registration errors and along or cross track tilts, are differenced from Shuttle Radar Topographic Mission (SRTM) data (2000) to yield surface lowering estimates. Landsat data and a hypsometric index (HI), a classification scheme used to group glaciers of similar hypsometry, are used to examine the distribution of glacier area with altitude in each catchment. Surface lowering rates of >3 m/yr can be detected on some glaciers, generally around the clean-ice/debris-cover boundary, where dark but thin surface deposits are likely to enhance ablation. More generally, surface lowering rates of around 1 m/yr are more pervasive, except around the terminus areas of most glaciers, emphasising the influence of a thick debris cover on ice melt. Surface lowering is only concentrated at glacier termini where glacial lakes have developed, where surface lowering rates are commonly greater than 2.5 m/yr. The three catchments show contrasting hypsometric distributions, which is likely to impact their future response to climatic changes. Glaciers of the Dudh Koshi basin store large volumes of ice at low elevation (HI > 1.5) in long, debris covered tongues, although their altitudinal range is greatest given the height of mountain peaks in the catchment. In contrast, glaciers of the Tama Koshi

  6. Subglacial discharge-driven renewal of tidewater glacier fjords

    NASA Astrophysics Data System (ADS)

    Carroll, Dustin; Sutherland, David A.; Shroyer, Emily L.; Nash, Jonathan D.; Catania, Ginny A.; Stearns, Leigh A.

    2017-08-01

    The classic model of fjord renewal is complicated by tidewater glacier fjords, where submarine melt and subglacial discharge provide substantial buoyancy forcing at depth. Here we use a suite of idealized, high-resolution numerical ocean simulations to investigate how fjord circulation driven by subglacial plumes, tides, and wind stress depends on fjord width, grounding line depth, and sill height. We find that the depth of the grounding line compared to the sill is a primary control on plume-driven renewal of basin waters. In wide fjords the plume exhibits strong lateral recirculation, increasing the dilution and residence time of glacially-modified waters. Rapid drawdown of basin waters by the subglacial plume in narrow fjords allows for shelf waters to cascade deep into the basin; wide fjords result in a thin, boundary current of shelf waters that flow toward the terminus slightly below sill depth. Wind forcing amplifies the plume-driven exchange flow; however, wind-induced vertical mixing is limited to near-surface waters. Tidal mixing over the sill increases in-fjord transport of deep shelf waters and erodes basin stratification above the sill depth. These results underscore the first-order importances of fjord-glacier geometry in controlling circulation in tidewater glacier fjords and, thus, ocean heat transport to the ice.

  7. A glacier runoff extension to the Precipitation Runoff Modeling System

    USGS Publications Warehouse

    Van Beusekom, Ashley E.; Viger, Roland

    2016-01-01

    A module to simulate glacier runoff, PRMSglacier, was added to PRMS (Precipitation Runoff Modeling System), a distributed-parameter, physical-process hydrological simulation code. The extension does not require extensive on-glacier measurements or computational expense but still relies on physical principles over empirical relations as much as is feasible while maintaining model usability. PRMSglacier is validated on two basins in Alaska, Wolverine, and Gulkana Glacier basin, which have been studied since 1966 and have a substantial amount of data with which to test model performance over a long period of time covering a wide range of climatic and hydrologic conditions. When error in field measurements is considered, the Nash-Sutcliffe efficiencies of streamflow are 0.87 and 0.86, the absolute bias fractions of the winter mass balance simulations are 0.10 and 0.08, and the absolute bias fractions of the summer mass balances are 0.01 and 0.03, all computed over 42 years for the Wolverine and Gulkana Glacier basins, respectively. Without taking into account measurement error, the values are still within the range achieved by the more computationally expensive codes tested over shorter time periods.

  8. Assessing glacier melt contribution to streamflow at Universidad Glacier, central Andes of Chile

    NASA Astrophysics Data System (ADS)

    Bravo, Claudio; Loriaux, Thomas; Rivera, Andrés; Brock, Ben W.

    2017-07-01

    Glacier melt is an important source of water for high Andean rivers in central Chile, especially in dry years, when it can be an important contributor to flows during late summer and autumn. However, few studies have quantified glacier melt contribution to streamflow in this region. To address this shortcoming, we present an analysis of meteorological conditions and ablation for Universidad Glacier, one of the largest valley glaciers in the central Andes of Chile at the head of the Tinguiririca River, for the 2009-2010 ablation season. We used meteorological measurements from two automatic weather stations installed on the glacier to drive a distributed temperature-index and runoff routing model. The temperature-index model was calibrated at the lower weather station site and showed good agreement with melt estimates from an ablation stake and sonic ranger, and with a physically based energy balance model. Total modelled glacier melt is compared with river flow measurements at three sites located between 0.5 and 50 km downstream. Universidad Glacier shows extremely high melt rates over the ablation season which may exceed 10 m water equivalent in the lower ablation area, representing between 10 and 13 % of the mean monthly streamflow at the outlet of the Tinguiririca River Basin between December 2009 and March 2010. This contribution rises to a monthly maximum of almost 20 % in March 2010, demonstrating the importance of glacier runoff to streamflow, particularly in dry years such as 2009-2010. The temperature-index approach benefits from the availability of on-glacier meteorological data, enabling the calculation of the local hourly variable lapse rate, and is suited to high melt regimes, but would not be easily applicable to glaciers further north in Chile where sublimation is more significant.

  9. Unraveling the Hydrology of the Glacierized Kaidu Basin by Integrating Multisource Data in the Tianshan Mountains, Northwestern China

    NASA Astrophysics Data System (ADS)

    Shen, Yan-Jun; Shen, Yanjun; Fink, Manfred; Kralisch, Sven; Brenning, Alexander

    2018-01-01

    Understanding the water balance, especially as it relates to the distribution of runoff components, is crucial for water resource management and coping with the impacts of climate change. However, hydrological processes are poorly known in mountainous regions due to data scarcity and the complex dynamics of snow and glaciers. This study aims to provide a quantitative comparison of gridded precipitation products in the Tianshan Mountains, located in Central Asia and in order to further understand the mountain hydrology and distribution of runoff components in the glacierized Kaidu Basin. We found that gridded precipitation products are affected by inconsistent biases based on a spatiotemporal comparison with the nearest weather stations and should be evaluated with caution before using them as boundary conditions in hydrological modeling. Although uncertainties remain in this data-scarce basin, driven by field survey data and bias-corrected gridded data sets (ERA-Interim and APHRODITE), the water balance and distribution of runoff components can be plausibly quantified based on the distributed hydrological model (J2000). We further examined parameter sensitivity and uncertainty with respect to both simulated streamflow and different runoff components based on an ensemble of simulations. This study demonstrated the possibility of integrating gridded products in hydrological modeling. The methodology used can be important for model applications and design in other data-scarce mountainous regions. The model-based simulation quantified the water balance and how the water resources are partitioned throughout the year in Tianshan Mountain basins, although the uncertainties present in this study result in important limitations.

  10. Resonance properties of tidal channels with multiple retention basins: role of adjacent sea

    NASA Astrophysics Data System (ADS)

    Roos, Pieter C.; Schuttelaars, Henk M.

    2015-03-01

    We present an idealised model of the tidal response in a main channel with multiple secondary basins, co-oscillating with an adjacent sea. The sea is represented as a semi-infinite strip of finite width, anywhere between the limits of a channel extension (narrow) and a half-plane (wide). The sea geometry controls the extent to which radiative damping takes place and hence the type of conditions that effectively apply at the channel mouth. These conditions range between the two extremes of prescribing elevation (deep sea limit) and prescribing the incoming wave (sea as channel extension of the same depth, as done in an earlier study). The closer to this first extreme, the stronger the oscillations in the secondary basins may feed back onto the channel mouth and thus produce an amplified or weakened response in the system as a whole. The possibly resonant response is explained by analysing the additional waves that emerge on either side of the entrance of the secondary basin. Finally, we show that the simultaneous presence of two secondary basins may amplify or weaken the accumulated responses to these basins individually.

  11. Climatic controls on the pace of glacier erosion

    NASA Astrophysics Data System (ADS)

    Koppes, Michele; Hallet, Bernard; Rignot, Eric; Mouginot, Jeremie; Wellner, Julia; Love, Katherine

    2016-04-01

    Mountain ranges worldwide have undergone large-scale modification due the erosive action of ice, yet the mechanisms that control the timing of this modification and the rate by which ice erodes remain poorly understood. Available data report a wide range of erosion rates from individual ice masses over varying timescales, suggesting that modern erosion rates exceed orogenic rates by 2-3 orders of magnitude. These modern rates are presumed to be due to dynamic acceleration of the ice masses during deglaciation and retreat. Recent numerical models have focused on replicating the processes that produce the geomorphic signatures of glacial landscapes. Central to these models is a simple quantitative index that relates erosion rate to ice dynamics and to climate. To provide such an index, we examined explicitly the factors controlling modern glacier erosion rates across climatic regimes. Holding tectonic history, bedrock lithology and glacier hypsometries relatively constant across a latitudinal transect from Patagonia to the Antarctic Peninsula, we find that modern, basin-averaged erosion rates vary by three orders of magnitude, from 1->10 mm yr-1 for temperate tidewater glaciers to 0.01-<0.1 mm yr-1 for polar outlet glaciers, largely as a function of temperature and basal thermal regime. Erosion rates also increase non-linearly with both the sliding speed and the ice flux through the ELA, in accord with theory. The general relationship between ice dynamics and erosion suggests that the erosion rate scales non-linearly with basal sliding speed, with an exponent n ≈ 2-2.62. Notably, erosion rates decrease by over two orders of magnitude between temperate and polar glaciers with similar ice discharge rates. The difference in erosion rates between temperate and colder glaciers of similar shape and size is primarily related to the abundance of meltwater accessing the bed. Since all glaciers worldwide have experienced colder than current climatic conditions, the 100-fold

  12. Preliminary bathymetry of Blackstone Bay and Neoglacial changes of Blackstone Glaciers, Alaska

    USGS Publications Warehouse

    Post, Austin

    1980-01-01

    Preliminary bathymetry (at 1:20,000 scale) and scientific studies of Blackstone Bay Alaska, by the Research Vessel Growler in 1978 disclose that the head of the bay consists of two basins separated by Willard Island and a submarine ridge. Both basins are closed on the north by terminal-moraine bars where Blackstone Glacier and its tributaries terminated as recently as about A.D. 1350; a carbon-14 date of 580 years before present on Badger Point, and old trees farther up the bay, disclose that the glaciers retreated to two narrow inlets at the head of the bay before 1400. The inlets were still glacier-covered until at least 1909. Glaciers in both inlets have continued to retreat; at present they terminate at the head of tidewater, where they discharge small icebergs. Only relatively thin sediments have accumulated in the eastern basin south of the terminal-moraine bar, and most of the bottom is hard and irregular as disclosed by soundings and profiles. The northern part of Blackstone Bay is very deep; at more than 1,100 feet below sea level a large, level accumulation of sediment is present which is presumably as much as 1,000 feet deep and has been accumulating since late Pleistocene glaciers retreated. (USGS)

  13. Asia's glaciers are a regionally important buffer against drought.

    PubMed

    Pritchard, Hamish D

    2017-05-10

    The high mountains of Asia-encompassing the Himalayas, the Hindu Kush, Karakoram, Pamir Alai, Kunlun Shan, and Tian Shan mountains-have the highest concentration of glaciers globally, and 800 million people depend in part on meltwater from them. Water stress makes this region vulnerable economically and socially to drought, but glaciers are a uniquely drought-resilient source of water. Here I show that these glaciers provide summer meltwater to rivers and aquifers that is sufficient for the basic needs of 136 million people, or most of the annual municipal and industrial needs of Pakistan, Tajikistan, Turkmenistan, Uzbekistan and Kyrgyzstan. During drought summers, meltwater dominates water inputs to the upper Indus and Aral river basins. Uncertainties in mountain precipitation are poorly known, but, given the magnitude of this water supply, predicted glacier loss would add considerably to drought-related water stress. Such additional water stress increases the risk of social instability, conflict and sudden, uncontrolled population migrations triggered by water scarcity, which is already associated with the large and rapidly growing populations and hydro-economies of these basins.

  14. Simulating and predicting snow and glacier meltwater to the runoff of the Upper Mekong River basin in Southwest China

    NASA Astrophysics Data System (ADS)

    Han, Z.; Long, D.; Hong, Y.

    2017-12-01

    Snow and glacier meltwater in cryospheric regions replenishes groundwater and reservoir storage and is critical to water supply, hydropower development, agricultural irrigation, and ecological integrity. Accurate simulating and predicting snow and glacier meltwater is therefore fundamental to develop a better understanding of hydrological processes and water resource management for alpine basins and its lower reaches. The Upper Mekong River (or the Lancang River in China) as one of the most important transboundary rivers originating from the Tibetan Plateau (TP), features active dam construction and complicated water resources allocation of the stakeholders. Confronted by both climate change and significant human activities, it is imperative to examine contributions of snow and glacier meltwater to the total runoff and how it will change in the near future. This will greatly benefit hydropower development in the upper reach of the Mekong and better water resources allocation and management across the relevant countries. This study aims to improve snowfall and snow water equivalent (SWE) simulation using improved methods, and combines both modeling skill and remote sensing (i.e., passive microwave-based SWE, and satellite gravimetry-based total water storage) to quantify the contributions of snow and glacier meltwater there. In addition, the runoff of the Lancang River under a range of climate change scenarios is simulated using the improved modeling scheme to evaluate how climate change will impact hydropower development in the upper reaches.

  15. Learning Non-Adjacent Regularities at Age 0 ; 7

    ERIC Educational Resources Information Center

    Gervain, Judit; Werker, Janet F.

    2013-01-01

    One important mechanism suggested to underlie the acquisition of grammar is rule learning. Indeed, infants aged 0 ; 7 are able to learn rules based on simple identity relations (adjacent repetitions, ABB: "wo fe fe" and non-adjacent repetitions, ABA: "wo fe wo", respectively; Marcus et al., 1999). One unexplored issue is…

  16. Changes in glacier dynamics in the northern Antarctic Peninsula since 1985

    NASA Astrophysics Data System (ADS)

    Seehaus, Thorsten; Cook, Alison J.; Silva, Aline B.; Braun, Matthias

    2018-02-01

    The climatic conditions along the northern Antarctic Peninsula have shown significant changes within the last 50 years. Here we present a comprehensive analysis of temporally and spatially detailed observations of the changes in ice dynamics along both the east and west coastlines of the northern Antarctic Peninsula. Temporal evolutions of glacier area (1985-2015) and ice surface velocity (1992-2014) are derived from a broad multi-mission remote sensing database for 74 glacier basins on the northern Antarctic Peninsula ( < 65° S along the west coast and north of the Seal Nunataks on the east coast). A recession of the glaciers by 238.81 km2 is found for the period 1985-2015, of which the glaciers affected by ice shelf disintegration showed the largest retreat by 208.59 km2. Glaciers on the east coast north of the former Prince Gustav Ice Shelf extent in 1986 receded by only 21.07 km2 (1985-2015) and decelerated by about 58 % on average (1992-2014). A dramatic acceleration after ice shelf disintegration with a subsequent deceleration is observed at most former ice shelf tributaries on the east coast, combined with a significant frontal retreat. In 2014, the flow speed of the former ice shelf tributaries was 26 % higher than before 1996. Along the west coast the average flow speeds of the glaciers increased by 41 %. However, the glaciers on the western Antarctic Peninsula revealed a strong spatial variability of the changes in ice dynamics. By applying a hierarchical cluster analysis, we show that this is associated with the geometric parameters of the individual glacier basins (hypsometric indexes, maximum surface elevation of the basin, flux gate to catchment size ratio). The heterogeneous spatial pattern of ice dynamic evolutions at the northern Antarctic Peninsula shows that temporally and spatially detailed observations as well as further monitoring are necessary to fully understand glacier change in regions with such strong topographic and climatic variances.

  17. Modeling the Impact of Fjord-glacier Geometry on Subglacial Plume, Wind, and Tidally-forced Circulation in Outlet Glacier Fjords

    NASA Astrophysics Data System (ADS)

    Carroll, D.; Sutherland, D.; Nash, J. D.; Shroyer, E.; de Steur, L.; Catania, G. A.; Stearns, L. A.

    2016-12-01

    The acceleration, retreat, and thinning of Greenland's outlet glaciers coincided with a warming of Atlantic waters, suggesting that marine-terminating glaciers are sensitive to ocean forcing. However, we still lack a precise understanding of what factors control the variability of ocean heat transport toward the glacier terminus. Here we use an idealized ocean general circulation model (3D MITgcm) to systematically evaluate how fjord circulation driven by subglacial plumes, wind stress (along-fjord and along-shelf), and tides depends on grounding line depth, fjord width, sill height, and latitude. Our results indicate that while subglacial plumes in deeply grounded systems can draw shelf waters over a sill and toward the glacier, shallowly grounded systems require external forcing to renew basin waters. We use a coupled sea ice model to explore the competing influence of tidal mixing and surface buoyancy forcing on fjord stratification. Passive tracers injected in the plume, fjord basin, and shelf waters are used to quantify turnover timescales. Finally, we compare our model results with a two-year mooring record to explain fundamental differences in observed circulation and hydrography in Rink Isbræ and Kangerlussuup Sermia fjords in west Greenland. Our results underscore the first-order effect that geometry has in controlling fjord circulation and, thus, ocean heat flux to the ice.

  18. Permian plate margin volcanism and tuffs in adjacent basins of west Gondwana: Age constraints and common characteristics

    NASA Astrophysics Data System (ADS)

    López-Gamundí, Oscar

    2006-12-01

    Increasing evidence of Permian volcanic activity along the South American portion of the Gondwana proto-Pacific margin has directed attention to its potential presence in the stratigraphic record of adjacent basins. In recent years, tuffaceous horizons have been identified in late Early Permian-through Middle Permian (280-260 Ma) sections of the Paraná Basin (Brazil, Paraguay, and Uruguay). Farther south and closer to the magmatic tract developed along the continental margin, in the San Rafael and Sauce Grande basins of Argentina, tuffs are present in the Early to Middle Permian section. This tuff-rich interval can be correlated with the appearance of widespread tuffs in the Karoo Basin. Although magmatic activity along the proto-Pacific plate margin was continuous during the Late Paleozoic, Choiyoi silicic volcanism along the Andean Cordillera and its equivalent in Patagonia peaked between the late Early Permian and Middle Permian, when extensive rhyolitic ignimbrites and consanguineous airborne tuffaceous material erupted in the northern Patagonian region. The San Rafael orogenic phase (SROP) interrupted sedimentation along the southwestern segment of the Gondwana margin (i.e., Frontal Cordillera, San Rafael Basin), induced cratonward thrusting (i.e., Ventana and Cape foldbelts), and triggered accelerated subsidence in the adjacent basins (Sauce Grande and Karoo) located inboard of the deformation front. This accelerated subsidence favored the preservation of tuffaceous horizons in the syntectonic successions. The age constraints and similarities in composition between the volcanics along the continental margin and the tuffaceous horizons in the San Rafael, Sauce Grande, Paraná, and Karoo basins strongly suggest a genetic linkage between the two episodes. Radiometric ages from tuffs in the San Rafael, Paraná, and Karoo basins indicate an intensely tuffaceous interval between 280 and 260 Ma.

  19. Late Holocene spatio-temporal variability of the south Greenland Ice Sheet and adjacent mountain glaciers

    NASA Astrophysics Data System (ADS)

    Sinclair, G.; Carlson, A. E.; Rood, D. H.; Axford, Y.

    2017-12-01

    The late Holocene, with its spatially complex pattern of centennial-scale climate variation, is an ideal time period to test the response of the cryosphere to atmospheric and oceanic temperature changes. The south Greenland Ice Sheet (sGrIS), with its proximity to areas of North Atlantic Deep Water formation and a large spectrum of glaciological regimes over a relatively small area, provides an excellent location to examine the spatial heterogeneity of ice-sheet and glacier responses to climate change. Here, we will present 50 Be-10 surface exposure ages from eight moraines in six locations around the margin of the sGrIS. These moraines are located just outboard of historical moraines, and will therefore allow us to constrain the timing of the most extensive prehistoric late-Holocene advance and retreat of ice margins draining the sGrIS and independent valley glaciers. The dataset includes both marine- and land-terminating glaciers draining the sGrIS, the low-altitude Qassimiut lobe, the high-altitude alpine Julianhåb ice cap and isolated valley glaciers. This diverse dataset will allow us to determine to what extent late-Holocene centennial-scale behavior of the ice-sheet and glacier margins were synchronous, perhaps in response to an external climate forcing, or more stochastic, governed instead by local factors such as basal thermal regime, bedrock topography, or microclimates. This has implications for understanding the forcings and responses of cryospheric changes at timescales relevant to human society. In addition to providing context for paleoclimatic and glacial geologic investigations, this work will inform future sea-level projections by providing targets for validating high-resolution ice-sheet and glacier models.

  20. Asia’s glaciers are a regionally important buffer against drought

    NASA Astrophysics Data System (ADS)

    Pritchard, Hamish D.

    2017-05-01

    The high mountains of Asia—encompassing the Himalayas, the Hindu Kush, Karakoram, Pamir Alai, Kunlun Shan, and Tian Shan mountains—have the highest concentration of glaciers globally, and 800 million people depend in part on meltwater from them. Water stress makes this region vulnerable economically and socially to drought, but glaciers are a uniquely drought-resilient source of water. Here I show that these glaciers provide summer meltwater to rivers and aquifers that is sufficient for the basic needs of 136 million people, or most of the annual municipal and industrial needs of Pakistan, Tajikistan, Turkmenistan, Uzbekistan and Kyrgyzstan. During drought summers, meltwater dominates water inputs to the upper Indus and Aral river basins. Uncertainties in mountain precipitation are poorly known, but, given the magnitude of this water supply, predicted glacier loss would add considerably to drought-related water stress. Such additional water stress increases the risk of social instability, conflict and sudden, uncontrolled population migrations triggered by water scarcity, which is already associated with the large and rapidly growing populations and hydro-economies of these basins.

  1. Glacier contribution to streamflow in two headwaters of the Huasco River, Dry Andes of Chile

    NASA Astrophysics Data System (ADS)

    Gascoin, S.; Kinnard, C.; Ponce, R.; Lhermitte, S.; MacDonell, S.; Rabatel, A.

    2011-12-01

    Quantitative assessment of glacier contribution to present-day streamflow is a prerequisite to the anticipation of climate change impact on water resources in the Dry Andes. In this paper we focus on two glaciated headwater catchments of the Huasco Basin (Chile, 29° S). The combination of glacier monitoring data for five glaciers (Toro 1, Toro 2, Esperanza, Guanaco, Estrecho and Ortigas) with five automatic streamflow records at sites with glacier coverage of 0.4 to 11 % allows the estimation of the mean annual glacier contribution to discharge between 2003/2004 and 2007/2008 hydrological years. In addition, direct manual measurements of glacier runoff were conducted in summer at the snouts of four glaciers, which provide the instantaneous contribution of glacier meltwater to stream runoff during summer. The results show that the mean annual glacier contribution to streamflow ranges between 3.3 and 23 %, which is greater than the glaciated fraction of the catchments. We argue that glacier contribution is partly enhanced by the effect of snowdrift from the non-glacier area to the glacier surface. Glacier mass loss is evident over the study period, with a mean of -0.84 m w.e. yr-1 for the period 2003/2004-2007/2008, and also contributes to increase glacier runoff. An El Niño episode in 2002 resulted in high snow accumulation, modifying the hydrological regime and probably reducing the glacier contribution in favor of seasonal snowmelt during the subsequent 2002/2003 hydrological year. At the hourly timescale, summertime glacier contributions are highly variable in space and time, revealing large differences in effective melting rates between glaciers and glacierets (from 1 mm w.e. h-1 to 6 mm w.e. h-1).

  2. Sediment export, transient landscape response and catchment-scale connectivity following rapid climate warming and Alpine glacier recession

    NASA Astrophysics Data System (ADS)

    Lane, Stuart N.; Bakker, Maarten; Gabbud, Chrystelle; Micheletti, Natan; Saugy, Jean-Noël

    2017-01-01

    In the face of rapid climate warming, rapid glacier recession should lead to a marked increase in the spatial extent of the paraglacial zone in glaciated drainage basins. The extent of the paraglacial zone has been well established to be transient but there are very few studies of this transient response and what it means for sediment export. There is good reason to expect that glacier recession could increase basin-scale sediment connectivity as: sediment becomes less dependent on glacier surface transport; proglacial streams are more able to migrate laterally than subglacial streams and so access sediment for transport; and glacier debuttressing may aid the development of gullies that can dissect moraines and so aid hillslope to proglacial zone connectivity. By using records of the flushing of hydroelectric power installations we were able to develop a record of coarse sediment (sand and gravel) export from a basin with a rapidly retreating valley glacier, the Haut Glacier d'Arolla, from 1977 to 2014. Modelling suggested that these data could only be partially controlled by transport capacity implying an important role for sediment supply and potentially for the influence of changing sediment connectivity. Indeed, there was evidence of the effects of glacial debuttressing upon gullying processes and hence a possible increase in the ease of connection of upstream basins to the proglacial area. More recently, we were able to show possible temperature control on sediment export, which may only have become apparent because of the progressive development of better sediment connectivity. However, whilst rapid glacier recession should result in theory in a progressive increase in connectivity of sediment sources to the basin outlet, the supply to capacity ratio does not increase continually with glacier recession until maximum capacity is reached. We identified two possible examples of why. First, gullying was also accompanied by the sediment accumulation at the base of

  3. Columbia Glacier stake location, mass balance, glacier surface altitude, and ice radar data, 1978 measurement year

    USGS Publications Warehouse

    Mayo, L.R.; Trabant, D.C.; March, Rod; Haeberli, Wilfried

    1979-01-01

    A 1 year data-collection program on Columbia Glacier, Alaska has produced a data set consisting of near-surface ice kinematics, mass balance, and altitude change at 57 points and 34 ice radar soundings. These data presented in two tables, are part of the basic data required for glacier dynamic analysis, computer models, and predictions of the number and size of icebergs which Columbia Glacier will calve into shipping lanes of eastern Prince William Sound. A metric, sea-level coordinate system was developed for use in surveying throughout the basin. Its use is explained and monument coordinates listed. A series of seven integrated programs for calculators were used in both the field and office to reduce the surveying data. These programs are thoroughly documented and explained in the report. (Kosco-USGS)

  4. The Bossons glacier protects Europe's summit from erosion

    NASA Astrophysics Data System (ADS)

    Godon, C.; Mugnier, J. L.; Fallourd, R.; Paquette, J. L.; Pohl, A.; Buoncristiani, J. F.

    2013-08-01

    The contrasting efficiency of erosion beneath cold glacier ice, beneath temperate glacier ice, and on ice-free mountain slopes is one of the key parameters in the development of relief during glacial periods. Detrital geochronology has been applied to the subglacial streams of the north face of the Mont-Blanc massif in order to estimate the efficiency of erosional processes there. Lithologically this area is composed of granite intruded at ~303 Ma within an older polymetamorphic complex. We use macroscopic features (on ~10,000 clasts) and U-Pb dating of zircon (~500 grains) to establish the provenance of the sediment transported by the glacier and its subglacial streams. The lithology of sediment collected from the surface and the base of the glacier is compared with the distribution of bedrock sources. The analysis of this distribution takes into account the glacier's surface flow lines, the surface areas beneath temperate and cold ice above and below the Equilibrium Line Altitude (ELA), and the extent of the watersheds of the three subglacial meltwater stream outlets located at altitudes of 2300 m, 1760 m and 1450 m. Comparison of the proportions of granite and metamorphics in these samples indicates that (1) glacial transport does not mix the clasts derived from subglacial erosion with the clasts derived from supraglacial deposition, except in the lower part of the ice tongue where supraglacial streams and moulins transfer the supraglacial load to the base of the glacier; (2) the glacial erosion rate beneath the tongue is lower than the erosion rate in adjacent non-glaciated areas; and (3) glacial erosion beneath cold ice is at least 16 times less efficient than erosion beneath temperate ice. The low rates of subglacial erosion on the north face of the Mont-Blanc massif mean that its glaciers are protecting "the roof of Europe" from erosion. A long-term effect of this might be a rise in the maximum altitude of the Alps.

  5. Recent Observations and Structural Analysis of Surge-Type Glaciers in the Glacier Bay Area

    NASA Astrophysics Data System (ADS)

    Mayer, H.; Herzfeld, U. C.

    2003-12-01

    The Chugach-St.-Elias Mountains in North America hold the largest non-polar connected glaciated area of the world. Most of its larger glaciers are surge-type glaciers. In the summer of 2003, we collected aerial photographic and GPS data over numerous glaciers in the eastern St. Elias Mountains, including the Glacier Bay area. Observed glaciers include Davidson, Casement, McBride, Riggs, Cushing, Carroll, Rendu, Tsirku, Grand Pacific, Melbern, Ferris, Margerie, Johns Hopkins, Lamplugh, Reid, Burroughs, Morse, Muir and Willard Glaciers, of which Carroll, Rendu, Ferris, Grand Pacific, Johns Hopkins and Margerie Glaciers are surge-type glaciers. Our approach utilizes a quantitative analysis of surface patterns, following the principles of structural geology for the analysis of brittle-deformation patterns (manifested in crevasses) and ductile deformation patterns (visible in folded moraines). First results will be presented.

  6. Glacier meltwater flow paths and storage in a geomorphologically complex glacial foreland: The case of the Tapado glacier, dry Andes of Chile (30°S)

    NASA Astrophysics Data System (ADS)

    Pourrier, J.; Jourde, H.; Kinnard, C.; Gascoin, S.; Monnier, S.

    2014-11-01

    The Tapado catchment is located in the upper Elqui river basin (4000-5550 m) in northern Chile. It comprises the Tapado glacial complex, which is an assemblage of the Tapado glacier and the glacial foreland (debris-covered glacier, rock glacier, and moraines). Although the hydrological functioning of this catchment is poorly known, it is assumed to actively supply water to the lower semi-arid areas of the Elqui river basin. To improve our knowledge of the interactions and water transfers between the cryospheric compartment (glacier, debris-covered glacier, and rock glacier) and the hydrological compartment (aquifers, streams), the results of monitoring of meteorological conditions, as well as discharge, conductivity and temperature of streams and springs located in the Tapado catchment were analyzed. The hydrological results are compared to results inferred from a ground penetrating radar (GPR) survey of the underground structure of the glacial foreland. Water production from the Tapado glacier was shown to be highly correlated with daily and monthly weather conditions, particularly solar radiation and temperature. The resulting daily and monthly streamflow cycles were buffered by the glacial foreland, where underground transfers took place through complex flow paths. However, the development of a thermokarst drainage network in a portion of the glacial foreland enabled rapid concentrated water transfers that reduced the buffer effect. The glacial foreland was shown to act as a reservoir, storing water during high melt periods and supplying water to downstream compartments during low melt periods. GPR observations revealed the heterogeneity of the internal structure of the glacial foreland, which is composed of a mixture of ice and rock debris mixture, with variable spatial ice content, including massive ice lenses. This heterogeneity may explain the abovementioned hydrological behaviors. Finally, calculation of a partial hydrological budget confirmed the

  7. Modeling the effect of glacier recession on streamflow response using a coupled glacio-hydrological model

    DOE PAGES

    Frans, Chris D.; Clarke, Garry K. C.; Burns, P.; ...

    2014-02-27

    Here, we describe an integrated spatially distributed hydrologic and glacier dynamic model, and use it to investigate the effect of glacier recession on streamflow variations for the Upper Bow River basin, a tributary of the South Saskatchewan River. Several recent studies have suggested that observed decreases in summer flows in the South Saskatchewan River are partly due to the retreat of glaciers in the river's headwaters. Modeling the effect of glacier changes on streamflow response in river basins such as the South Saskatchewan is complicated due to the inability of most existing physically-based distributed hydrologic models to represent glacier dynamics.more » We compare predicted variations in glacier extent, snow water equivalent and streamflow discharge made with the integrated model with satellite estimates of glacier area and terminus position, observed streamflow and snow water equivalent measurements over the period of 1980 2007. Simulations with the coupled hydrology-glacier model reduce the uncertainty in streamflow predictions. Our results suggested that on average, the glacier melt contribution to the Bow River flow upstream of Lake Louise is about 30% in summer. For warm and dry years, however, the glacier melt contribution can be as large as 50% in August, whereas for cold years, it can be as small as 20% and the timing of glacier melt signature can be delayed by a month.« less

  8. Geologic interpretation of gravity data from the Date Creek basin and adjacent areas, west-central Arizona

    USGS Publications Warehouse

    Otton, James K.; Wynn, Jeffrey C.

    1978-01-01

    A gravity survey of the Date Creek Basin and adjacent areas was conducted in June 1977 to provide information for the interpretation of basin geology. A comparison of facies relations in the locally uraniferous Chapin Wash Formation and the position of the Anderson mine gravity anomaly in the Date Creek Basin suggested that a relationship between gravity lows and the development of thick lacustrine sections in the region might exist. A second-order residual gravity map derived from the complete Bouguer gravity map for the survey area (derived from survey data and pre-existing U.S. Department of Defense data) shows an excellent correspondence between gravity lows and sediment-filled basins and suggests considerable variation in basin-fill thickness. Using the Anderson mine anomaly as a model, gravity data and facies relations suggest that the southeastern flank of the Aguila Valley gravity low and the gravity low at the western end of the Hassayampa Plain are likely areas for finding thick sections of tuffaceous lacustrine rocks.

  9. Spatiotemporal variations of radar glacier zones in the Karakoram Mountains

    NASA Astrophysics Data System (ADS)

    Lund, Jewell

    2017-04-01

    Glaciers of the Karakoram Mountains are important climate indicators for densely populated South Central Asia. Glacial meltwater is a significant source of runoff in the Indus River Basin, upon which 60 million people rely for food security, economy and hydropower in Pakistan and India. Contrary to worldwide and also Himalayan trends, Karakoram glaciers have recently been verified in near balance, with some glaciers even gaining mass or surging. This 'Karakoram anomaly' is of interest, and many hypotheses exist for its causes. Complex climatology, coupled with the challenges of field study in this region, illicit notable uncertainties both in observation and prediction of glacial status. Constraining spatiotemporal variations in glacial mass balance will elucidate the extent and possible longevity of this anomaly, and its implications for water resources, as climate continues to change. Depending on snowpack conditions during image acquisition, different snow and ice zones on a glacier are identifiable in synthetic aperture radar (SAR) images. The identification and monitoring of radar glacier zones over time can provide indicators of relative glacial mass balance to compliment field studies in a region with sparse field measurement. We will present spatiotemporal evolution of basic radar glacier zones such as wet snow, bare ice, percolation, and firn for glaciers feeding into the Upper Indus Basin. We will incorporate both ascending and descending passes of Sentinel-1 series C -band sensors, and possibly ALOS-2 PALSAR-2 L-band images. We may also explore the impacts of these variations on timing and intensity of runoff.

  10. Preliminary bathymetry of Aialik Bay and Neoglacial changes of Aialik and Pederson glaciers, Alaska

    USGS Publications Warehouse

    Post, Austin

    1980-01-01

    Preliminary bathymetry (at 1:20,000 scale) and scientific studies of Aialik Bay, Alaska, by the Research Vessel Growler in 1978 disclose that the head of the bay consists of a deep basin enclosed by a terminal-moraine shoal. A much smaller basin, into which Aialik Glacier discharges icebergs, is located west of two islands and a submarine ridge. Comparison of 1978 soundings with U.S. Coast and Geodetic Survey (now National Oceanic and Atmospheric Administration) data obtained in 1912 shows shoaling of about 64 feet in the deepest part of the small basin nearest the glacier and of about 40 feet in the large basin. The time of retreat of Aialik Glacier from the moraine bar is unknown; a faint ' trimline ' is still visible in the forest on the east side of the fiord, and a carbon-14 date suggests the retreat could have taken place as recently as 1800. The time of Aialik Glcier 's neoglacial advance to the moraine is unknown. Pederson Glacier, which terminates in part in a tidal lagoon or lake, has retreated about 0.90 mile from a moraine judged by Grant and Higgins to have been in contact with the ice about 1896. (USGS)

  11. Glacier Dynamics Within a Small Alpine Cirque

    NASA Astrophysics Data System (ADS)

    Sanders, J. W.; Cuffey, K. M.; MacGregor, K. R.; Kavanaugh, J. L.; Dow, C. F.

    2008-12-01

    Cirques, with their steep walls and overdeepened basins, have captivated the imagination of scientists since the mid-1800s. Glaciers in cirques, by generating these spectacular amphitheater-shaped landforms, contribute significantly to erosion in the core of mountain ranges and are one of the principal agents responsible for the relief structure at high elevations. Yet comprehensive studies of the dynamics of cirque glaciers, and their link to erosional processes, have never been undertaken. To this end, we acquired an extensive new set of measurements at the West Washmawapta Glacier, which sits in a cirque on the east side of Helmet Mountain in the Vermillion Range of the Canadian Rockies. Ice thickness surveys with ground penetrating radar revealed that the glacier occupies a classic bowl-shaped depression complete with a nearly continuous riegel. Using GPS-derived surface velocities of a glacier-wide grid network and the tilt of one borehole, we calculated the complete force balance of the glacier. This analysis also produced a map of basal sliding velocity and a value for the viscosity of temperate ice. We will discuss the implications of these findings for the problem of how cirques are formed by glacial erosion.

  12. Geodetic measurements used to estimate ice transfer during Bering Glacier surge

    NASA Astrophysics Data System (ADS)

    Sauber, Jeanne; Plafker, George; Gipson, John

    The application of geodetic measurements to glacial research has found a new testing ground: near a surging Alaskan glacier. A set of geodetic measurements collected adjacent to the Bagley Icefield (Figure 1) and along the Gulf of Alaska (Figure 2) are being used to estimate the effects of the Bering Glacier surge that began in the spring of 1993. When ice is removed from a glacier's reservoir during a surge, its surface lowers by tens or hundreds of meters and ice is added to the receiving area, where it thickens and advances.The dramatic changes in a surging glacier's extent and thickness should result in elastic deformation of the solid Earth. At Bering Glacier, calculations show that ice transfer may have caused up to 17 cm of the solid Earth to subside. Although recent surges at the Bering and Variegated Glaciers have been well documented, little is known about most surges, particularly about what happens in the upper reaches of the glaciers.

  13. Historical glacier outlines from digitized topographic maps of the Swiss Alps

    NASA Astrophysics Data System (ADS)

    Freudiger, Daphné; Mennekes, David; Seibert, Jan; Weiler, Markus

    2018-04-01

    Since the end of the Little Ice Age around 1850, the total glacier area of the central European Alps has considerably decreased. In order to understand the changes in glacier coverage at various scales and to model past and future streamflow accurately, long-term and large-scale datasets of glacier outlines are needed. To fill the gap between the morphologically reconstructed glacier outlines from the moraine extent corresponding to the time period around 1850 and the first complete dataset of glacier areas in the Swiss Alps from aerial photographs in 1973, glacier areas from 80 sheets of a historical topographic map (the Siegfried map) were manually digitized for the publication years 1878-1918 (further called first period, with most sheets being published around 1900) and 1917-1944 (further called second period, with most sheets being published around 1935). The accuracy of the digitized glacier areas was then assessed through a two-step validation process: the data were (1) visually and (2) quantitatively compared to glacier area datasets of the years 1850, 1973, 2003, and 2010, which were derived from different sources, at the large scale, basin scale, and locally. The validation showed that at least 70 % of the digitized glaciers were comparable to the outlines from the other datasets and were therefore plausible. Furthermore, the inaccuracy of the manual digitization was found to be less than 5 %. The presented datasets of glacier outlines for the first and second periods are a valuable source of information for long-term glacier mass balance or hydrological modelling in glacierized basins. The uncertainty of the historical topographic maps should be considered during the interpretation of the results. The datasets can be downloaded from the FreiDok plus data repository (https://freidok.uni-freiburg.de/data/15008,

  14. Application of artificial neural networks in hydrological modeling: A case study of runoff simulation of a Himalayan glacier basin

    NASA Technical Reports Server (NTRS)

    Buch, A. M.; Narain, A.; Pandey, P. C.

    1994-01-01

    The simulation of runoff from a Himalayan Glacier basin using an Artificial Neural Network (ANN) is presented. The performance of the ANN model is found to be superior to the Energy Balance Model and the Multiple Regression model. The RMS Error is used as the figure of merit for judging the performance of the three models, and the RMS Error for the ANN model is the latest of the three models. The ANN is faster in learning and exhibits excellent system generalization characteristics.

  15. Glacier, Glacial Lake, and Ecological Response Dynamics of the Imja Glacier-Lake-Moraine System, Nepal

    NASA Astrophysics Data System (ADS)

    Kargel, J. S.; Shugar, D. H.; Leonard, G. J.; Haritashya, U. K.; Harrison, S.; Shrestha, A. B.; Mool, P. K.; Karki, A.; Regmi, D.

    2016-12-01

    Glacier response dynamics—involving a host of processes—produce a sequence of short- to long-term delayed responses to any step-wise, oscillating, or continuous trending climatic perturbation. We present analysis of Imja Lake, Nepal and examine its thinning and retreat and a sequence of the detachment of tributaries; the inception and growth of Imja Lake and concomitant glacier retreat, thinning, and stagnation, and relationships to lake dynamics; the response dynamics of the ice-cored moraine; the development of the local ecosystem; prediction of short-term dynamical responses to lake lowering (glacier lake outburst flood—GLOF—mitigation); and prospects for coming decades. The evolution of this glacier system provides a case study by which the global record of GLOFs can be assessed in terms of climate change attribution. We define three response times: glacier dynamical response time (for glacier retreat, thinning, and slowing of ice flow), limnological response time (lake growth), and GLOF trigger time (for a variety of hazardous trigger events). Lake lowering (to be completed in August 2016; see AGU abstract by D. Regmi et al.) will reduce hazards, but we expect that the elongation of the lake and retreat of the glacier will continue for decades after a pause in 2016-2017. The narrowing of the moraine dam due to thaw degradation of the ice-cored end moraine means that the hazard due to Imja Lake will soon again increase. We examine both long-term response dynamics, and two aspects of Himalayan glaciers that have very rapid responses: the area of Imja Lake fluctuates seasonally and even with subseasonal weather variations in response to changes in lake temperature and glacier meltback; and as known from other studies, glacier flow speed can vary between years and even on shorter timescales. The long-term development and stabilization of glacial moraines and small lacustrine plains in drained lake basins impacts the development of local ecosystems

  16. Marine ice sheet collapse potentially under way for the Thwaites Glacier Basin, West Antarctica.

    PubMed

    Joughin, Ian; Smith, Benjamin E; Medley, Brooke

    2014-05-16

    Resting atop a deep marine basin, the West Antarctic Ice Sheet has long been considered prone to instability. Using a numerical model, we investigated the sensitivity of Thwaites Glacier to ocean melt and whether its unstable retreat is already under way. Our model reproduces observed losses when forced with ocean melt comparable to estimates. Simulated losses are moderate (<0.25 mm per year at sea level) over the 21st century but generally increase thereafter. Except possibly for the lowest-melt scenario, the simulations indicate that early-stage collapse has begun. Less certain is the time scale, with the onset of rapid (>1 mm per year of sea-level rise) collapse in the different simulations within the range of 200 to 900 years. Copyright © 2014, American Association for the Advancement of Science.

  17. Surface expression of subglacial meltwater movement, Bering Glacier, Alaska

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cadwell, D.H.; Fleisher, P.J.; Bailey, P.K.

    1993-03-01

    Longitudinal topographic profiles (1988--1992) across the thermokarst terminus of the Grindle Hills Ice-tongue and interlobate moraine of the Bering Piedmont Glacier document annual changes in crevasse patterns and fluctuations in surface elevation related to subglacial water movement. A semi-continuous record of aerial photos (1978--1990), plus field observations (1988--1992), reveal the progressive enlargement of two lateral collapse basin on both sides of the thermokarst, connected by a transverse collapse trough. Seasonally generated meltwater at depth rises within the glacier, fills the basins and other depressions and lifts the thermokarst terminus of the ice-tongue a few meters by buoyancy and hydrostatic pressure.more » The resulting surface tension creates a chaotic crevasse pattern unrelated to normal glacier movement. The crevasses open (2 m wide, 8--10 m deep) in response to increased water accumulation at depth and close during subsidence as the ice-tongue settles following evacuation of subglacier water. A network of open conduits (>10 m diameter), exposed by surface ablation, provides evidence for the scale of englacial passageways beneath the thermokarst and represents a form of subglacial ablation that leads to removal of support and collapse in stagnant glacier masses.« less

  18. Using the nonlinear aquifer storage-discharge relationship to simulate the base flow of glacier- and snowmelt-dominated basins in northwest China

    NASA Astrophysics Data System (ADS)

    Gan, R.; Luo, Y.

    2013-09-01

    Base flow is an important component in hydrological modeling. This process is usually modeled by using the linear aquifer storage-discharge relation approach, although the outflow from groundwater aquifers is nonlinear. To identify the accuracy of base flow estimates in rivers dominated by snowmelt and/or glacier melt in arid and cold northwestern China, a nonlinear storage-discharge relationship for use in SWAT (Soil Water Assessment Tool) modeling was developed and applied to the Manas River basin in the Tian Shan Mountains. Linear reservoir models and a digital filter program were used for comparisons. Meanwhile, numerical analysis of recession curves from 78 river gauge stations revealed variation in the parameters of the nonlinear relationship. It was found that the nonlinear reservoir model can improve the streamflow simulation, especially for low-flow period. The higher Nash-Sutcliffe efficiency, logarithmic efficiency, and volumetric efficiency, and lower percent bias were obtained when compared to the one-linear reservoir approach. The parameter b of the aquifer storage-discharge function varied mostly between 0.0 and 0.1, which is much smaller than the suggested value of 0.5. The coefficient a of the function is related to catchment properties, primarily the basin and glacier areas.

  19. Glacier Evolution in the Altai Mountains, South-West Siberia, for the Last Half Century (with use of Geo-Informational Catalogue)

    NASA Astrophysics Data System (ADS)

    Surazakov, A. B.; Narojniy, Y. K.; Nikitin, S. A.; Aizen, V. B.

    2003-12-01

    To systemize and analyze the information for the period from 1835 to present on altitudinal distributions of glaciers, exposition, their numbers and surface areas in basins, volumes, genetic classification, location of lower and upper level of glaciers, average firn line position and main morphometric characteristics, DataBase on glacier dynamics in the Altai Mountains (AGDB) has been developed in ArcGIS Format [Tomsk State University, Russia]. Data from Glacier Catalogue [1962], topographic maps with the scale of 1:25000 and 1:50000 and air photos, which fixed glaciers' state on 1952, were digitized. Instrumental observational data on glacier tongue retreat from twenty glaciers since 1835, and radio-echo sounding measurements of 120 glacier volumes were also digitized in the AGDB. Modern state of Altai glaciers and their changes since 1952 were assessed from Resurs space images and partially from instrumental observations. Based on estimation from Resurs for the period from 1952 to 1998, the value of Altai glacier retreating was about 56.9 km2, i.e. 7.1 % of total area, varied from 4 % for valley glaciers to 16 % for glaciers of flat mountain tops. Retreat of 2-8 m per year was accompanied by their 10% mass loss. The slightest degradation occurred in inner (central) part of the glacier system, in the heads of river basins with large-scale glaciation, e.g., in the Katunski, Nothern-Chuiski and Southern-Chuiski ranges, amounting to 6.3%. These are the highest regions, reaching up to 4506 m., and 80% of Altai's glaciers are located there. In the river basins with relatively small-glacierized areas, at the peripheral regions, e.g., Kurai, Chihacheva ranges, the degradation reached its maximum values up to 22%.

  20. Summary of the geology and resources of uranium in the San Juan Basin and adjacent region, New Mexico, Arizona, Utah, and Colorado

    USGS Publications Warehouse

    Ridgley, Jennie L.; Green, M.W.; Pierson, C.T.; Finch, W.I.; Lupe, R.D.

    1978-01-01

    The San Juan Basin and adjacent region lie predominantly in the southeastern part of the uranium-rich Colorado Plateau of New Mexico, Arizona, Utah, and Colorado. Underlying the province are rocks of the Precambrian basement complex composed mainly of igneous and metamorphic rocks; a thickness of about 3,600 meters of generally horizontal Paleozoic, Mesozoic, and Cenozoic sedimentary rocks; and a variety of Upper Cretaceous and Cenozoic igneous rocks. Sedimentary rocks of the sequence are commonly eroded and well exposed near the present basin margins where Tertiary tectonic activity has uplifted, folded, and faulted the sequence into its present geologic configuration of basins, platforms, monoclines, and other related structural features. Sedimentary rocks of Jurassic age in the southern part of the San Juan Basin contain the largest uranium deposits in the United States, and offer the promise of additional uranium deposits. Elsewhere in the basin and the adjacent Colorado Plateau, reserves and resources of uranium are known primarily in Triassic, Jurassic, and Cretaceous strata. Only scattered occurrences of uranium are known in Paleozoic

  1. Antarctic Peninsula Tidewater Glacier Dynamics

    NASA Astrophysics Data System (ADS)

    Pettit, E. C.; Scambos, T. A.; Haran, T. M.; Wellner, J. S.; Domack, E. W.; Vernet, M.

    2015-12-01

    The northern Antarctic Peninsula (nAP, north of 66°S) is a north-south trending mountain range extending transverse across the prevailing westerly winds of the Southern Ocean resulting in an extreme west-to-east precipitation gradient. Snowfall on the west side of the AP is one to two orders of magnitude higher than the east side. This gradient drives short, steep, fast-flowing glaciers into narrow fjords on the west side, while longer lower-sloping glaciers flow down the east side into broader fjord valleys. This pattern in ice dynamics affects ice-ocean interaction on timescales of decades to centuries, and shapes the subglacial topography and submarine bathymetry on timescales of glacial cycles. In our study, we calculate ice flux for the western and eastern nAP using a drainage model that incorporates the modern ice surface topography, the RACMO-2 precipitation estimate, and recent estimates of ice thinning. Our results, coupled with observed rates of ice velocity from InSAR (I. Joughin, personal communication) and Landsat 8 -derived flow rates (this study), provide an estimate of ice thickness and fjord depth in grounded-ice areas for the largest outlet glaciers. East-side glaciers either still terminate in or have recently terminated in ice shelves. Sedimentary evidence from the inner fjords of the western glaciers indicates they had ice shelves during LIA time, and may still have transient floating ice tongues (tabular berg calvings are observed). Although direct oceanographic evidence is limited, the high accumulation rate and rapid ice flux implies cold basal ice for the western nAP glaciers and therefore weak subglacial discharge relative to eastern nAP glaciers and or other tidewater fjord systems such as in Alaska. Finally, despite lower accumulation rates on the east side, the large elongate drainage basins result in a greater ice flux funneled through fewer deeper glaciers. Due to the relation between ice flux and erosion, these east-side glaciers

  2. Changes of glacier, glacier-fed rivers and lakes in Altai Tavan Bogd National Park, Western Mongolia, based on multispectral satellite data from 1990 to 2017

    NASA Astrophysics Data System (ADS)

    Batsaikhan, B.; Lkhamjav, O.; Batsaikhan, N.

    2017-12-01

    Impacts on glaciers and water resource management have been altering through climate changes in Mongolia territory characterized by dry and semi-arid climate with low precipitation. Melting glaciers are early indicators of climate change unlike the response of the forests which is slower and takes place over a long period of time. Mountain glaciers are important environmental components of local, regional, and global hydrological cycles. The study calculates an overview of changes for glacier, glacier-fed rivers and lakes in Altai Tavan Bogd mountain, the Western Mongolia, based on the indexes of multispectral data and the methods typically applied in glacier studies. Were utilized an integrated approach of Normalized Difference Snow Index (NDSI) and Normalized Difference Water Index (NDWI) to combine Landsat, MODIS imagery and digital elevation model, to identify glacier cover are and quantify water storage change in lakes, and compared that with and climate parameters including precipitation, land surface temperature, evaporation, moisture. Our results show that melts of glacier at the study area has contributed to significantly increase of water storage of lakes in valley of The Altai Tavan Bogd mountain. There is hydrologic connection that lake basin is directly fed by glacier meltwater.

  3. Laramide structure of the central Sangre de Cristo Mountains and adjacent Raton Basin, southern Colorado

    USGS Publications Warehouse

    Lindsey, D.A.

    1998-01-01

    Laramide structure of the central Sangre de Cristo Mountains (Culebra Range) is interpreted as a system of west-dipping, basement-involved thrusts and reverse faults. The Culebra thrust is the dominant structure in the central part of the range; it dips 30 -55?? west and brings Precambrian metamorphic base-ment rocks over unmetamorphosed Paleozoic rocks. East of the Culebra thrust, thrusts and reverse faults break the basement and overlying cover rocks into north-trending fault blocks; these boundary faults probably dip 40-60?? westward. The orientation of fault slickensides indicates oblique (northeast) slip on the Culebra thrust and dip-slip (ranging from eastward to northward) movement on adjacent faults. In sedimentary cover rocks, east-vergent anticlines overlie and merge with thrusts and reverse faults; these anticlines are interpreted as fault-propagation folds. Minor east-dipping thrusts and reverse faults (backthrusts) occur in both the hanging walls and footwalls of thrusts. The easternmost faults and folds of the Culebra Range form a continuous structural boundary between the Laramide Sangre de Cristo highland and the Raton Basin. Boundary structures consist of west-dipping frontal thrusts flanked on the basinward side by poorly exposed, east-dipping backthrusts. The backthrusts are interpreted to overlie structural wedges that have been emplaced above blind thrusts in the basin margin. West-dipping frontal thrusts and blind thrusts are interpreted to involve basement, but backthrusts are rooted in basin-margin cover rocks. At shallow structural levels where erosion has not exposed a frontal thrust, the structural boundary of the basin is represented by an anticline or monocline. Based on both regional and local stratigraphic evidence, Laramide deformation in the Culebra Range and accompanying synorogenic sedimentation in the western Raton Basin probably took place from latest Cretaceous through early Eocene time. The earliest evidence of uplift and

  4. Processing multiple non-adjacent dependencies: evidence from sequence learning

    PubMed Central

    de Vries, Meinou H.; Petersson, Karl Magnus; Geukes, Sebastian; Zwitserlood, Pienie; Christiansen, Morten H.

    2012-01-01

    Processing non-adjacent dependencies is considered to be one of the hallmarks of human language. Assuming that sequence-learning tasks provide a useful way to tap natural-language-processing mechanisms, we cross-modally combined serial reaction time and artificial-grammar learning paradigms to investigate the processing of multiple nested (A1A2A3B3B2B1) and crossed dependencies (A1A2A3B1B2B3), containing either three or two dependencies. Both reaction times and prediction errors highlighted problems with processing the middle dependency in nested structures (A1A2A3B3_B1), reminiscent of the ‘missing-verb effect’ observed in English and French, but not with crossed structures (A1A2A3B1_B3). Prior linguistic experience did not play a major role: native speakers of German and Dutch—which permit nested and crossed dependencies, respectively—showed a similar pattern of results for sequences with three dependencies. As for sequences with two dependencies, reaction times and prediction errors were similar for both nested and crossed dependencies. The results suggest that constraints on the processing of multiple non-adjacent dependencies are determined by the specific ordering of the non-adjacent dependencies (i.e. nested or crossed), as well as the number of non-adjacent dependencies to be resolved (i.e. two or three). Furthermore, these constraints may not be specific to language but instead derive from limitations on structured sequence learning. PMID:22688641

  5. Mass Loss of Larsen B Tributary Glaciers (Antarctic Peninsula) Unabated Since 2002

    NASA Technical Reports Server (NTRS)

    Berthier, Etienne; Scambos, Ted; Shuman, Christopher A.

    2012-01-01

    Ice mass loss continues at a high rate among the large glacier tributaries of the Larsen B Ice Shelf following its disintegration in 2002. We evaluate recent mass loss by mapping elevation changes between 2006 and 201011 using differencing of digital elevation models (DEMs). The measurement accuracy of these elevation changes is confirmed by a null test, subtracting DEMs acquired within a few weeks. The overall 2006201011 mass loss rate (9.0 2.1 Gt a-1) is similar to the 2001022006 rate (8.8 1.6 Gt a-1), derived using DEM differencing and laser altimetry. This unchanged overall loss masks a varying pattern of thinning and ice loss for individual glacier basins. On Crane Glacier, the thinning pulse, initially greatest near the calving front, is now broadening and migrating upstream. The largest losses are now observed for the HektoriaGreen glacier basin, having increased by 33 since 2006. Our method has enabled us to resolve large residual uncertainties in the Larsen B sector and confirm its state of ongoing rapid mass loss.

  6. Decrease in glacier coverage contributes to increased winter baseflow of Arctic rivers

    NASA Astrophysics Data System (ADS)

    Liljedahl, A. K.; Gaedeke, A.; Baraer, M.; Chesnokova, A.; Lebedeva, L.; Makarieva, O.; O'Neel, S.

    2016-12-01

    Rising minimum daily flows in northern Eurasian and North American rivers suggest a growing influence of groundwater in the Arctic hydrological cycle, while the impact of a warmer high-latitude climate system is evident in decreased glacier coverage and increasing permafrost temperatures. Multiple mechanisms have been proposed to explain the increased discharge, which is well documented but relatively poorly understood. Here we assess the long-term (up to 88 yrs) linkages between climate, glaciers and hydrology in Alaska, Canadian and Russian glacierized (from 0.3 to 60% glacier cover) and non-glacierized watersheds (31 to 186 000 km2). We are specifically interested in analyzing trends in late winter discharge from larger watersheds to refine our understanding of the regional aquifer status and annual discharge from smaller headwater basins. Field measurements of differential runoff in Interior Alaska show that glaciated headwater streams can lose significant amounts of water in summer to the underlying aquifer. The aquifer is in turn feeding the larger lowland river system throughout the year. Groundwater storage status in Arctic regions is especially prominent through winter river discharge as it is typically the only source of water to the river system for at least 6 months of the year. Our analyses aim to explore the hypothesis that the documented increase in later winter river discharge of larger watersheds can be explained at least partly, by increased glacier melt in summer as observed by long-term decreases in glacier coverage. If true, a decrease in winter freshwater exports to the Arctic Ocean could potentially follow as glaciers retreat to higher (cooler) elevations. Increased Arctic river baseflow can favor sea ice growth and fish habitats, while negatively impacting local communities in their river ice travel.

  7. Observed Melt Season Seismicity of Taylor Glacier, Antarctica

    NASA Astrophysics Data System (ADS)

    Carmichael, J. D.; Pettit, E. C.; Creager, K. C.

    2006-12-01

    Sufficient evidence exists to suggest that interaction of crevasses and meltwater accelerates ice cliff disintegration of tidewater glaciers. It is not clear what role meltwater plays in calving characteristics from dry- based polar glaciers. We have obtained seismic data from a six-sensor seismic array deployed in October of 2004 near the terminus cliffs of Taylor Glacier, West Antarctica, to analyze near-cliff seismicity throughout a melt season. Discharge data from the adjacent Lawson stream suggests that dramatic increases in meltwater volume temporally correlate with changes in seismic character near ice cliffs. We calculated source-locations for ice-quake during hours of melting and re-freezing and found most large energy events to be located near the ice cliffs. The associated spectra and waveform characteristics are indicative of literature descriptions of crevassing events.

  8. Rapid thinning and collapse of lake calving Yakutat Glacier, Southeast Alaska

    NASA Astrophysics Data System (ADS)

    Trussel, Barbara Lea

    Glaciers around the globe are experiencing a notable retreat and thinning, triggered by atmospheric warming. Tidewater glaciers in particular have received much attention, because they have been recognized to contribute substantially to global sea level rise. However, lake calving glaciers in Alaska show increasingly high thinning and retreat rates and are therefore contributors to sea level rise. The number of such lake calving systems is increasing worldwide as land-terminating glaciers retreat into overdeepened basins and form proglacial lakes. Yakutat Glacier in Southeast Alaska is a low elevation lake calving glacier with an accumulation to total area ratio of 0.03. It experienced rapid thinning of 4.43 +/- 0.06 m w.e. yr-1 between 2000-2010 and terminus retreat of over 15 km since the beginning of the 20th century. Simultaneously, adjacent Yakutat Icefield land-terminating glaciers thinned at lower but still substantial rates (3.54 +/- 0.06 m w.e. yr -1 for the same time period), indicating lake calving dynamics help drive increased mass loss. Yakutat Glacier sustained a ˜3 km long floating tongue for over a decade, which started to disintegrate into large tabular icebergs in 2010. Such floating tongues are rarely seen on temperate tidewater glaciers. The floating ice was weakened by surface ablation, which then allowed rifts to form and intersect. Ice velocity from GPS measurements showed that the ice on the floating tongue was moving substantially faster than grounded ice, which was attributed to rift opening between the floating and grounded ice. Temporal variations of rift opening were determined from time-lapse imagery, and correlated well with variations in ice speeds. Larger rift opening rates occurred during and after precipitation or increased melt episodes. Both of these events increased subglacial discharge and could potentially increase the subaqueous currents towards the open lake and thus increase drag on the ice underside. Simultaneously

  9. Correlation of sea level falls interpreted from atoll stratigraphy with turbidites in adjacent basins

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lincoln, J.M.

    Past sea levels can be derived from any atoll subsurface sediments deposited at or near sea level by determining the ages of deposition and correcting the present depths to the sediments for subsidence of the underlying edifice since the times of deposition. A sea level curve constructed by this method consists of discontinuous segments, each corresponding to a period of rising relative sea level and deposition of a discrete sedimentary package. Discontinuities in the sea level curve derived by this method correspond to relative sea level falls and stratigraphic hiatuses in the atoll subsurface. During intervals of relative sea levelmore » fall an atoll emerges to become a high limestone island. Sea level may fluctuate several times during a period of atoll emergence to become a high limestone island. Sea level may fluctuate several times during a period of atoll emergence without depositing sediments on top of the atoll. Furthermore, subaerial erosion may remove a substantial part of the depositional record of previous sea level fluctuations. For these reasons the authors must look to the adjacent basins to complement the incomplete record of sea level change recorded beneath atolls. During lowstands of sea level, faunas originally deposited near sea level on an atoll may be eroded and redeposited as turbidites in deep adjacent basins. Three such turbidites penetrated during deep-sea drilling at Sites 462 and 315 in the central Pacific correlate well with a late Tertiary sea level curve based on biostratigraphic ages and {sup 87}Sr/{sup 86}Sr chronostratigraphy for core from Enewetak Atoll in the northern Marshall Islands. Further drilling of the archipelagic aprons adjacent to atolls will improve the sea level history that may be inferred from atoll stratigraphy.« less

  10. Remote Sensing Observations of Advancing and Surging Tidewater Glaciers

    NASA Astrophysics Data System (ADS)

    McNabb, R. W.; Kääb, A.; Nuth, C.; Girod, L.; Truffer, M.; Fahnestock, M. A.

    2017-12-01

    Progress has been made in understanding the glaciological frontiers of tidewater glacier dynamics and surge dynamics, though many aspects of these topics are not well-understood. Advances in the processing of digital elevation models (DEMs) from ASTER imagery, as well as the increased availability and temporal density of satellite images such as Landsat and the Sentinel missions, provide an unprecedented wealth of satellite data over glaciers, providing new opportunities to learn about these topics. As one of the largest glaciated regions in the world outside of the Greenland and Antarctic ice sheets, glaciers in Alaska and adjacent regions in Canada have been highlighted for their elevated contributions to global sea level rise, through both high levels of melt and frontal ablation/calving from a large number of tidewater glaciers. The region is also home to a number of surging glaciers. We focus on several tidewater glaciers in the region, including Turner, Tsaa, Harvard, and Meares Glaciers. Turner Glacier is a surge-type tidewater glacier with a surge period of approximately eight years, while Tsaa Glacier is a tidwewater glacier that has shown rapid swings in terminus position on the order of a year. Harvard and Meares Glaciers have been steadily advancing since at least the mid-20th century, in contrast with neighboring glaciers that are retreating. Using a combination of ASTER, Landsat, and Sentinel data, we present and examine high-resolution time series of elevation, velocity, and terminus position for these glaciers, as well as updated estimates of volume change and frontal ablation rates, including on sub-annual time scales. Preliminary investigations of elevation change on Turner Glacier show that changes are most pronounced in the lower reaches of the glacier, below a prominent icefall approximately 15km from the head of the glacier. On Harvard and Meares Glaciers, elevation changes in the upper reaches of both glaciers have been generally small or

  11. New insights into trace elements deposition in the snow packs at remote alpine glaciers in the northern Tibetan Plateau, China.

    PubMed

    Dong, Zhiwen; Kang, Shichang; Qin, Xiang; Li, Xiaofei; Qin, Dahe; Ren, Jiawen

    2015-10-01

    Trace element pollution resulting from anthropogenic emissions is evident throughout most of the atmosphere and has the potential to create environmental and health risks. In this study we investigated trace element deposition in the snowpacks at two different locations in the northern Tibetan Plateau, including the Laohugou (LHG) and the Tanggula (TGL) glacier basins, and its related atmospheric pollution information in these glacier areas, mainly focusing on 18 trace elements (Li, Be, V, Cr, Co, Ni, Cu, Zn, Ga, Rb, Nb, Mo, Cd, Sb, Cs, Ba, Tl, and Pb). The results clearly demonstrate that pronounced increases of both concentrations and crustal enrichment factors (EFs) are observed in the snowpack at the TGL glacier basin compared to that of the LHG glacier basin, with the highest EFs for Sb and Zn in the TGL basin, whereas with the highest EFs for Sb and Cd in the LHG basin. Compared with other studies in the Tibetan Plateau and surrounding regions, trace element concentration showed gradually decreasing trend from Himalayan regions (southern Tibetan Plateau) to the TGL basin (central Tibetan Plateau), and to the LHG basin (northern Tibetan Plateau), which probably implied the significant influence of atmospheric trace element transport from south Asia to the central Tibetan Plateau. Moreover, EF calculations at two sites showed that most of the heavy metals (e.g., Cu, Zn, Mo, Cd, Sb, and Pb) were from anthropogenic sources and some other elements (e.g., Li, Rb, and Ba) were mainly originated from crustal sources. MODIS atmospheric optical depth (AOD) fields derived using the Deep Blue algorithm and CALIOP/CALIPSO transect showed significant influence of atmospheric pollutant transport from south Asia to the Tibetan Plateau, which probably caused the increased concentrations and EFs of trace element deposition in the snowpack on the TGL glacier basin. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Austrian glaciers in historical documents of the last 400 years: implications for historical hydrology

    NASA Astrophysics Data System (ADS)

    Fischer, Andrea; Seiser, Bernd

    2014-05-01

    First documentations of Austrian glaciers date from as early as 1601. Early documentations were triggered by glacier advances that created glacier-dammed lakes that caused floods whenever the dam collapsed . Since then, Austrian glaciers have been documented in drawings, descriptions and later on in maps and photography. These data are stored in historical archives but today only partly exploited for historical glaciology. They are of special interest for historical hydrology in glacier-covered basins, as the extent of the snow, firn and ice cover and its elevation affect the hydrological response of the basin to precipitation events in several ways: - Firn cover: the more area is covered by firn, the higher is the capacity for retention or even refreezing of liquid precipitation and melt water. - Ice cover: the area covered by glaciers can be affected by melt and contributes to a peak discharge on summer afternoons. - Surface elevation and temperatures: in case of precipitation events, the lower surface temperatures and higher surface elevation of the glaciers compared to ice-free ground have some impact on the capacity to store precipitation. - Glacier floods: for the LIA maximum around 1850, a number of advancing glaciers dammed lakes which emptied during floods. These parameters show different variability with time: glacier area varies only by about 60% to 70% between the LIA maximum and today. The variability of the maximum meltwater peak changes much more than the area. Even during the LIA maximum, several years were extremely warm, so that more than twice the size of today's glacier area was subject to glacier melt. The minimum elevations of large glaciers were several hundred meters lower than today, so that in terms of today's summer mean temperatures, the melt water production from ice ablation would have been much higher than today. A comparison of historical glacier images and description with today's makes it clear that the extent of the snow cover and

  13. Effects of lava-dome emplacement on the Mount St. Helens crater glacier

    NASA Astrophysics Data System (ADS)

    Walder, J. S.; Schilling, S. P.; Denlinger, R. P.; Vallance, J. W.

    2004-12-01

    Since the end of the 1981-1986 episode of lava-dome growth at Mount St. Helens, an unusual glacier has grown rapidly within the crater of the volcano. The glacier, which is fed primarily by avalanching from the crater walls, contains about 30% rock debris by volume, has a maximum thickness of about 220 m and a volume of about 120 million cubic m, and forms a crescent that wraps around the old lava dome on both east and west sides. The new (October 2004) lava dome in the south of the crater began to grow centered roughly on the contact between the old lava dome and the glacier, in the process uplifting both ice and old dome rock. As the new dome is spreading to the south, the adjacent glacier is bulging upward. Firn layers on the outer flank of the glacier bulge have been warped upward almost vertically. In contrast, ice adjacent to the new dome has been thoroughly fractured. The overall style of deformation is reminiscent of that associated with salt-dome intrusion. Drawing an analogy to sand-box experiments, we suggest that the glacier is being deformed by high-angle reverse faults propagating upward from depth. Comparison of Lidar images of the glacier from September 2003 and October 2004 reveals not only the volcanogenic bulge but also elevated domains associated with the passage of kinematic waves, which are caused by glacier-mass-balance perturbations and have nothing to do with volcanic activity. As of 25 October 2004, growth of the new lava dome has had negligible hydrological consequences. Ice-surface cauldrons are common consequences of intense melting caused by either subglacial eruptions (as in Iceland) or subglacial venting of hot gases (as presently taking place at Mount Spurr, Alaska). However, there has been a notable absence of ice-surface cauldrons in the Mount St. Helens crater glacier, aside from a short-lived pond formed where the 1 October eruption pierced the glacier. We suggest that heat transfer to the glacier base is inefficient because

  14. Monitoring of oceanographic properties of Glacier Bay, Alaska 2004

    USGS Publications Warehouse

    Madison, Erica N.; Etherington, Lisa L.

    2005-01-01

    Glacier Bay is a recently (300 years ago) deglaciated fjord estuarine system that has multiple sills, very deep basins, tidewater glaciers, and many streams. Glacier Bay experiences a large amount of runoff, high sedimentation, and large tidal variations. High freshwater discharge due to snow and ice melt and the presence of the tidewater glaciers makes the bay extremely cold. There are many small- and large-scale mixing and upwelling zones at sills, glacial faces, and streams. The complex topography and strong currents lead to highly variable salinity, temperature, sediment, primary productivity, light penetration, stratification levels, and current patterns within a small area. The oceanographic patterns within Glacier Bay drive a large portion of the spatial and temporal variability of the ecosystem. It has been widely recognized by scientists and resource managers in Glacier Bay that a program to monitor oceanographic patterns is essential for understanding the marine ecosystem and to differentiate between anthropogenic disturbance and natural variation. This year’s sampling marks the 12th continuous year of monitoring the oceanographic conditions at 23 stations along the primary axes within Glacier Bay, AK, making this a very unique and valuable data set in terms of its spatial and temporal coverage.

  15. Investigation on Glacier Thinning in Baspa, Western Himalaya.

    NASA Astrophysics Data System (ADS)

    S, P.; Kulkarni, A. V.; Bhushan, S.

    2017-12-01

    Mass balance studies are important to assess the state of glaciers. Previously, numerous field investigations have been carried out in Baspa basin to measure mass balance. However, mass balance data from field are limited to a small number of glaciers and for short durations. Therefore, this study uses geodetic mass balance technique to evaluate the mass loss at decadal scale. Geodetic method involves differencing Digital Elevation Model (DEM) from different years to obtain change in glacier elevation, which will be subsequently used to evaluate mass balance. This study derives mass balance from 2000 to 2014 for 16 glaciers covering a total area of 70 Sq Km. The study uses Shuttle Radar Topography Mission (SRTM) DEM for year 2000 and DEM for year 2014 was derived from Cartosat-1 stereo pair using photogrammetric principles. A Differential Global Positioning System (DGPS) survey was conducted in Baspa basin at different elevation zones to collect Ground Control Points (GCP) with millimeters accuracy. These GCP were used to derive Cartosat DEM. Various corrections were applied before differencing the two DEMs. They were co-registered using an analytical approach to account for horizontal shift. Corrections were also applied to remove the bias due to satellite acquisition geometry. SRTM DEM was acquired in February when the study area was covered by seasonal snow, whereas, Cartosat data was acquired during the ablation season. As the season of data acquisition varies for the two DEM, we have corrected for the bias that could be caused due to seasonal snow. Snowfall data from a meteorological station in the Baspa valley and a local precipitation gradient were used to determine the seasonal snow depth. Further, corrections were applied to account for the bias due to radar penetration in SRTM DEM. Then, the elevation changes were determined by subtracting the two DEMs to estimate mass balance. The figure below shows the change in glacier elevation. These results will be

  16. Glaciers along proposed routes extending the Copper River Highway, Alaska

    USGS Publications Warehouse

    Glass, R.L.

    1996-01-01

    Three inland highway routes are being considered by the Alaska Department of Transportation and Public Facilities to connect the community of Cordova in southcentral Alaska to a statewide road system. The routes use part of a Copper River and Northwest Railway alignment along the Copper River through mountainous terrain having numerous glaciers. An advance of any of several glaciers could block and destroy the roadway, whereas retreating glaciers expose large quantities of unconsolidated, unvegetated, and commonly ice-rich sediments. The purpose of this study was to map historical locations of glacier termini near these routes and to describe hazards associated with glaciers and seasonal snow. Historical and recent locations of glacier termini along the proposed Copper River Highway routes were determined by reviewing reports and maps and by interpreting aerial photographs. The termini of Childs, Grinnell, Tasnuna, and Woodworth Glaciers were 1 mile or less from a proposed route in the most recently available aerial photography (1978-91); the termini of Allen, Heney, and Schwan Glaciers were 1.5 miles or less from a proposed route. In general, since 1911, most glaciers have slowly retreated, but many glaciers have had occasional advances. Deserted Glacier and one of its tributary glaciers have surge-type medial moraines, indicating potential rapid advances. The terminus of Deserted Glacier was about 2.1 miles from a proposed route in 1978, but showed no evidence of surging. Snow and rock avalanches and snowdrifts are common along the proposed routes and will periodically obstruct the roadway. Floods from ice-dammed lakes also pose a threat. For example, Van Cleve Lake, adjacent to Miles Glacier, is as large as 4.4 square miles and empties about every 6 years. Floods from drainages of Van Cleve Lake have caused the Copper River to rise on the order of 20 feet at Million Dollar Bridge.

  17. Water flow through temperate glaciers

    USGS Publications Warehouse

    Fountain, A.G.; Walder, J.S.

    1998-01-01

    Understanding water movement through a glacier is fundamental to several critical issues in glaciology, including glacier dynamics, glacier-induced floods, and the prediction of runoff from glacierized drainage basins. to this end we have synthesized a conceptual model os water movement through a temperate glacier from the surface to the outlet stream. Processes that regulate the rate and distribution of water input at the glacier surface and that regulate water movement from the surface to the bed play important but commonly neglected roles in glacier hydrology. Where a glacier is covered by a layer of porous, permeable firn (the accumulation zone), the flux of water to the glacier interior varies slowly because the firn temporarily stores water and thereby smooths out variations in the supply rate. In the firn-free ablation zone, in contrast, the flux of water into the glacier depends directly on the rate of surface melt or rainfall and therefore varies greatly in time. Water moves from the surface to the bed through an upward branching arborescent network consisting of both steeply inclined conduits, formed by the enlargement of intergranular veins, and gently inclined conduits, sprqwned by water flow along the bottoms of near-surface fractures (crevasses). Englacial drainage conduits deliver water to the glacier bed at a linited number of points, probably a long distance downglacier of where water enters the glacier. Englacial conduits supplied from the accumulation zone are quasi steady state features that convey the slowly varying water flux delivered via the firn. their size adjusts so that they are usually full of water and flow is pressurized. In contrast, water flow in englacial conduits supplied from the ablation area is pressurized only near times of peak daily flow or during rainstorms; flow is otherwise in an open-channel configuration. The subglacial drainage system typically consists of several elements that are distinct both morpphologically and

  18. Deformation Rates in the Snake River Plain and Adjacent Basin and Range Regions Based on GPS Measurements

    NASA Astrophysics Data System (ADS)

    Payne, S. J.; McCaffrey, R.; King, R. W.; Kattenhorn, S. A.

    2012-12-01

    We estimate horizontal velocities for 405 sites using Global Positioning System (GPS) phase data collected from 1994 to 2010 within the Northern Basin and Range Province, U.S.A. The velocities reveal a slowly-deforming region within the Snake River Plain in Idaho and Owyhee-Oregon Plateau in Oregon separated from the actively extending adjacent Basin and Range regions by shear. Our results show a NE-oriented extensional strain rate of 5.6 ± 0.7 nanostrain/yr in the Centennial Tectonic Belt and an ~E-oriented extensional strain rate of 3.5 ± 0.2 nanostrain/yr in the Great Basin. These extensional rates contrast with the very low strain rate within the 125 km x 650 km region of the Snake River Plain and Owyhee-Oregon Plateau which is not distinguishable from zero (-0.1 ± 0.4 x nanostrain/yr). Inversions of Snake River Plain velocities with dike-opening models indicate that rapid extension by dike intrusion in volcanic rift zones, as previously hypothesized, is not currently occurring. GPS data also disclose that rapid extension in the surrounding regions adjacent to the slowly-deforming region of the Snake River Plain drives shear between them. We estimate right-lateral shear with slip rates of 0.3-1.5 mm/yr along the northwestern boundary adjacent to the Centennial Tectonic Belt and left-lateral oblique extension with slip rates of 0.5-1.5 mm/yr along the southeastern boundary adjacent to the Intermountain Seismic Belt. The fastest lateral shearing evident in the GPS occurs near the Yellowstone Plateau where earthquakes with right-lateral strike-slip focal mechanisms are within a NE-trending zone of seismicity. The regional velocity gradients are best fit by nearby poles of rotation for the Centennial Tectonic Belt, Snake River Plain, Owyhee-Oregon Plateau, and eastern Oregon, indicating that clockwise rotation is not locally driven by Yellowstone hotspot volcanism, but instead by extension to the south across the Wasatch fault possibly due to gravitational

  19. Microbial community development on the surface of Hans and Werenskiold Glaciers (Svalbard, Arctic): a comparison.

    PubMed

    Grzesiak, Jakub; Górniak, Dorota; Świątecki, Aleksander; Aleksandrzak-Piekarczyk, Tamara; Szatraj, Katarzyna; Zdanowski, Marek K

    2015-09-01

    Surface ice and cryoconite holes of two types of polythermal Svalbard Glaciers (Hans Glacier--grounded tidewater glacier and Werenskiold Glacier-land-based valley glacier) were investigated in terms of chemical composition, microbial abundance and diversity. Gathered data served to describe supraglacial habitats and to compare microbe-environment interactions on those different type glaciers. Hans Glacier samples displayed elevated nutrient levels (DOC, nitrogen and seston) compared to Werenskiold Glacier. Adjacent tundra formations, bird nesting sites and marine aerosol were candidates for allochtonic enrichment sources. Microbial numbers were comparable on both glaciers, with surface ice containing cells in the range of 10(4) mL(-1) and cryoconite sediment 10(8) g(-1) dry weight. Denaturating gradient gel electrophoresis band-based clustering revealed differences between glaciers in terms of dominant bacterial taxa structure. Microbial community on Werenskiold Glacier benefited from the snow-released substances. On Hans Glacier, this effect was not as pronounced, affecting mainly the photoautotrophs. Over-fertilization of Hans Glacier surface was proposed as the major factor, desensitizing the microbial community to the snow melt event. Nitrogen emerged as a limiting factor in surface ice habitats, especially to Eukaryotic algae.

  20. Monitoring of mountain glaciers of some regions of gissar-alai mountain system using aster space images

    NASA Astrophysics Data System (ADS)

    Batirov, R.; Yakovlev, A.

    In 1999 the TERRA orbital platform was launched. It is intended for space monitoring of various natural objects on a surface of the Earth and in particular of glaciers. Onboard the orbital platform the Japanese sensor ASTER was installed. Characteristics of the sensor give unique possibility for monitoring glaciers from the space. In the given work the cataloguing of glaciers of some river basins of Alai, Turkestan and Zeravshan ranges of Gissar--Alai mountain system, which in turn is a part of Pamir--Alai mountain system, was fulfilled. In particular, the cataloguing of glaciers of Shahimardan, Sokh, Isfara river basins, and also the basin of Zeravshan glacier was fulfilled. Thematic processing of the images was implemented for the range of the images on the date of the survey -- second half of August 2001--2002 years. The images were granted in the framework of Aster Research Opportunity Scheme (ARO) of Japanese space agency ERSDAC (``Monitoring of mountain glaciers and glacial lakes using ASTER space images'', contract AP-0290). Previous data of glaciation of this region were obtained as per 1957 and 1980 with application of materials of aerial photography (1957) and analogue space images (1980). The ASTER sensor makes survey an earth surface in 14 bands of a spectrum of electromagnetic waves radiated by the Sun -- from the visible up to the thermal infrared. Thus the following three bands are optimal for extraction of glaciological information: Band 1 (visible green) -- 0.52-0.60 microns; Band 2 (visible red) -- 0.63-0.69 microns; Band 3N (short-range infrared) -- 0.78-0.86 microns. The spatial resolution of these bands is 15 m, and radiometric resolution is 8 bits. Such geometrical and radiometric resolutions provide acceptable accuracy of definition of glaciers. At composition of the computer image in a pseudo-color, the red color was correlated with the band1, the green with the band 2 and the dark blue with the band 3N. Such selection of the bands gives the

  1. Southwest Greenland's Alpine Glacier History: Recent Glacier Change in the Context of the Holocene Geologic Record

    NASA Astrophysics Data System (ADS)

    Larocca, L. J.; Axford, Y.; Lasher, G. E.; Lee, C. W.

    2017-12-01

    Due to anthropogenic climate change, the Arctic region is currently undergoing major transformation, and is expected to continue warming much faster than the global average. To put recent and future changes into context, a longer-term understanding of this region's past response to natural climate variability is needed. Given their sensitivity to modest climate change, small alpine glaciers and ice caps on Greenland's coastal margin (beyond the Greenland Ice Sheet) represent ideal features to record climate variability through the Holocene. Here we investigate the Holocene history of a small ( 160 square km) ice cap and adjacent alpine glaciers, located in southwest Greenland approximately 50 km south of Nuuk. We employ measurements on sediment cores from a glacier-fed lake in combination with geospatial analysis of satellite images spanning the past several decades. Sedimentary indicators of sediment source and thus glacial activity, including organic matter abundance, inferred chlorophyll-a content, sediment major element abundances, grain size, and magnetic susceptibility are presented from cores collected from a distal glacier-fed lake (informally referred to here as Per's Lake) in the summer of 2015. These parameters reflect changes in the amount and character of inorganic detrital input into the lake, which may be linked to the size of the upstream glaciers and ice cap and allow us to reconstruct their status through the Holocene. Additionally, we present a complementary record of recent changes in Equilibrium Line Altitude (ELA) for the upstream alpine glaciers. Modern ELAs are inferred using the accumulation area ratio (AAR) method in ArcGIS via Landsat and Worldview-2 satellite imagery, along with elevation data obtained from digital elevation models (DEMs). Paleo-ELAs are inferred from the positions of moraines and trim lines marking the glaciers' most recent expanded state, which we attribute to the Little Ice Age (LIA). This approach will allow us to

  2. Cryopreserved embryo transfer: adjacent or non-adjacent to failed fresh long GnRH-agonist protocol IVF cycle.

    PubMed

    Volodarsky-Perel, Alexander; Eldar-Geva, Talia; Holzer, Hananel E G; Schonberger, Oshrat; Reichman, Orna; Gal, Michael

    2017-03-01

    The optimal time to perform cryopreserved embryo transfer (CET) after a failed oocyte retrieval-embryo transfer (OR-ET) cycle is unknown. Similar clinical pregnancy rates were recently reported in immediate and delayed CET, performed after failed fresh OR-ET, in cycles with the gonadotrophin-releasing hormone (GnRH) antagonist protocol. This study compared outcomes of CET performed adjacently (<50 days, n = 67) and non-adjacently (≥50 to 120 days, n = 62) to the last OR-day of cycles with the GnRH agonist down-regulation protocol. Additional inclusion criteria were patients' age 20-38 years, the transfer of only 1-2 cryopreserved embryos, one treatment cycle per patient and artificial preparation for CET. Significantly higher implantation, clinical pregnancy and live birth rates were found in the non-adjacent group than in the adjacent group: 30.5% versus 11.3% (P = 0.001), 41.9% versus 17.9% (P = 0.003) and 32.3% versus 13.4% (P = 0.01), respectively. These results support the postponement of CET after a failed OR-ET for at least one menstrual cycle, when a preceding long GnRH-agonist protocol is used. Copyright © 2016 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

  3. High Resolution Land Surface Modeling over the NEF Basin in the Chilean Patagonia

    NASA Astrophysics Data System (ADS)

    Somos-Valenzuela, M. A.

    2017-12-01

    Stakeholders and policy makers perceive that water and climate change adaptation are among the most vulnerable issues that need to be addressed. Therefore, there is a need not only from the scientific community but also from the society to use integrated methodologies that link advances in climatology with hydrology to provide data that helps us to provide adaptation strategies. The Andes and the Chilean-Argentinean Patagonia have been steadily warming up to 0.5 Celsius degrees per decades at the same time that precipitation is decreasing by 10 to 12 % per decade. In the future is expected that these trends will continue which will have impacts in the annual water budget. The Chilean Patagonia has brought a lot of attention during last decade because two hydroelectric project seek to build dams in one of the most pristine environments in the world. Also, in the Baker River basin a series of Glacier Lakes Outburst Flood have occurred which is perceived as an undeniable consequence of the effects of climate change in the glacier system. Major attention is mainly situated in the impact of climate change in glaciers contribution to sea level rise, GLOF studies given the numerous supra glacier lakes that are forming, and the study of stream flow point observation. The objectives of this research are: 1) Study the historical trends of precipitation, temperature, land cover changes and streamflow available in the Baker Basin; 2) Use a couple glacier model with a land surface model to predict the evolution of glaciers and their effects in the water availability. To address these objectives, I will analyze trends in hydro meteorology observations and correlation with trends in Land Cover Changes. Use the WRF-hydro framework to generate data in a small watershed that will allow to calibrate a high resolution hydro glaciology model to understand the partition between glaciered and non-glaciered runoff. The parameters estimated in the small domain could have the potential to

  4. Selected ground-water information for the Pasco basin and adjacent areas, Washington, 1986-1989

    USGS Publications Warehouse

    Drost, B.W.; Schurr, K.M.; Lum, W. E.

    1989-01-01

    The U.S. Geological Survey, in cooperation with the United States Department of Energy, conducted a study of the Pasco basin and adjacent areas, Washington, in support of the Basalt Waste Isolation Project at the Hanford site, Washington. The purpose of the study was to develop a data set that would help define the groundwater-flow system of the Pasco Basin. This report contains the basic data, without interpretation, that were collected from the start of the project in February 1986 through January 1989. Information presented is from the U.S. Bureau of Reclamation, State of Washington Department of Ecology , US Army Corps of Engineers, Kennewick Irrigation District, and the Survey, and consists of well location and construction data, records of water levels in the wells, and aquifer designations for each well. The aquifer designation represents the geohydrologic unit to which the well is reported to be open. (USGS)

  5. Glacial-hydrogeomorphic process of proglacial lake expansion and exploring its amplification effect on glacier recession in the Himalayas

    NASA Astrophysics Data System (ADS)

    Song, C.; Sheng, Y.; Wang, J.; Ke, L.; Nie, Y.

    2016-12-01

    Glacial lakes, as a key component of the cryosphere in the Himalayas in response to climate change, pose significant threats to the downstream lives and properties and eco-environment via outburst floods, yet our understanding of their evolution and reaction mechanism with connected glaciers is limited. Here, a regional investigation of glacial lake evolution and glacial-hydrogeomorphic process was conducted by integrating optical imagery, satellite altimetry and DEM. A classification scheme was first used to group glacial lakes of similar glacial and geo-morphology. Our studies show that debris-contact proglacial lakes experienced much more rapid expansions than ice cliff-contact and non-glacier-contact lakes. We further estimate the mass balance of parent glaciers and elevation changes in lake surfaces and debris-covered glacier tongues. Results reveal that the upstream expansion of debris-contact proglacial lakes was not directly related to rising water levels but with a geomorphological alternation of upstream lake basins caused by ice melt-induced debris subsidence at glacier termini. It suggests that the hydrogeomorphic process of glacier thinning and retreat, in comparison with direct meltwater supply alone, may have governed primarily the recent glacial lake expansion across the Himalayas. The mechanism of proglacial lake expansion provides an indirect way to estimate the lowering rates of glacier terminus. The debris-covered glacier fronts show considerable ice melts, with the lowering rate ranging from 1.0 to 9.7 m/yr. The rates exhibit obvious correlations with contacted lake sizes, centerline length and area of glaciers, suggesting that the glacier termini thinning is the combined effect of interplays between glacial lakes and ice flux from parent glaciers. Our study implies that substantial mass loss occurred at lake-contact glacier fronts, which cannot be ignored in assessing the overall mass balance of Himalayan glaciers.

  6. Biogeochemistry of hydrothermally and adjacent non-altered soils

    USDA-ARS?s Scientific Manuscript database

    As a field/lab project, students in the Soil Biogeochemistry class of the University of Nevada, Reno described and characterized seven pedons, developed in hydrothermally and adjacent non-hydrothermally altered andesitic parent material near Reno, NV. Hydrothermally altered soils had considerably lo...

  7. Pan–ice-sheet glacier terminus change in East Antarctica reveals sensitivity of Wilkes Land to sea-ice changes

    PubMed Central

    Miles, Bertie W. J.; Stokes, Chris R.; Jamieson, Stewart S. R.

    2016-01-01

    The dynamics of ocean-terminating outlet glaciers are an important component of ice-sheet mass balance. Using satellite imagery for the past 40 years, we compile an approximately decadal record of outlet-glacier terminus position change around the entire East Antarctic Ice Sheet (EAIS) marine margin. We find that most outlet glaciers retreated during the period 1974–1990, before switching to advance in every drainage basin during the two most recent periods, 1990–2000 and 2000–2012. The only exception to this trend was in Wilkes Land, where the majority of glaciers (74%) retreated between 2000 and 2012. We hypothesize that this anomalous retreat is linked to a reduction in sea ice and associated impacts on ocean stratification, which increases the incursion of warm deep water toward glacier termini. Because Wilkes Land overlies a large marine basin, it raises the possibility of a future sea level contribution from this sector of East Antarctica. PMID:27386519

  8. Pan-ice-sheet glacier terminus change in East Antarctica reveals sensitivity of Wilkes Land to sea-ice changes.

    PubMed

    Miles, Bertie W J; Stokes, Chris R; Jamieson, Stewart S R

    2016-05-01

    The dynamics of ocean-terminating outlet glaciers are an important component of ice-sheet mass balance. Using satellite imagery for the past 40 years, we compile an approximately decadal record of outlet-glacier terminus position change around the entire East Antarctic Ice Sheet (EAIS) marine margin. We find that most outlet glaciers retreated during the period 1974-1990, before switching to advance in every drainage basin during the two most recent periods, 1990-2000 and 2000-2012. The only exception to this trend was in Wilkes Land, where the majority of glaciers (74%) retreated between 2000 and 2012. We hypothesize that this anomalous retreat is linked to a reduction in sea ice and associated impacts on ocean stratification, which increases the incursion of warm deep water toward glacier termini. Because Wilkes Land overlies a large marine basin, it raises the possibility of a future sea level contribution from this sector of East Antarctica.

  9. Mapping tide-water glacier dynamics in east Greenland using landsat data

    USGS Publications Warehouse

    Dwyer, John L.

    1995-01-01

    Landsat multispectral scanner and thematic mapper images were co-registered For the Kangerdlugssuaq Fjord region in East Greenland and were used to map glacier drainage-basin areas, changes in the positions of tide-water glacier termini and to estimate surface velocities of the larger tide-water glaciers. Statistics were compiled to document distance and area changes to glacier termini. The methodologies developed in this study are broadly applicable to the investigation of tide-water glaciers in other areas. The number of images available for consecutive years and the accuracy with which images are co-registered are key factors that influence the degree to which regional glacier dynamics can be characterized using remotely sensed data.Three domains of glacier state were interpreted: net increase in terminus area in the southern part of the study area, net loss of terminus area for glaciers in upper Kangerdlugssuaq Fjord and a slight loss of glacier terminus area northward from Ryberg Fjord. Local increases in the concentrations of drifting icebergs in the fjords coincide with the observed extension of glacier termini positions Ice-surface velocity estimates were derived for several glaciers using automated image cross-correlation techniques The velocity determined for Kangerdlugssuaq Gletscher is approximately 5.0 km a−1 and that for Kong Christian IV Gletscher is 0.9 km a−1. The continuous presence of icebergs and brash ice in front of these glaciers indicates sustained rates of ice-front calving.

  10. Mass balance, meteorology, area altitude distribution, glacier-surface altitude, ice motion, terminus position, and runoff at Gulkana Glacier, Alaska, 1996 balance year

    USGS Publications Warehouse

    March, Rod S.

    2003-01-01

    The 1996 measured winter snow, maximum winter snow, net, and annual balances in the Gulkana Glacier Basin were evaluated on the basis of meteorological, hydrological, and glaciological data. Averaged over the glacier, the measured winter snow balance was 0.87 meter on April 18, 1996, 1.1 standard deviation below the long-term average; the maximum winter snow balance, 1.06 meters, was reached on May 28, 1996; and the net balance (from August 30, 1995, to August 24, 1996) was -0.53 meter, 0.53 standard deviation below the long-term average. The annual balance (October 1, 1995, to September 30, 1996) was -0.37 meter. Area-averaged balances were reported using both the 1967 and 1993 area altitude distributions (the numbers previously given in this abstract use the 1993 area altitude distribution). Net balance was about 25 percent less negative using the 1993 area altitude distribution than the 1967 distribution. Annual average air temperature was 0.9 degree Celsius warmer than that recorded with the analog sensor used since 1966. Total precipitation catch for the year was 0.78 meter, 0.8 standard deviations below normal. The annual average wind speed was 3.5 meters per second in the first year of measuring wind speed. Annual runoff averaged 1.50 meters over the basin, 1.0 standard deviation below the long-term average. Glacier-surface altitude and ice-motion changes measured at three index sites document seasonal ice-speed and glacier-thickness changes. Both showed a continuation of a slowing and thinning trend present in the 1990s. The glacier terminus and lower ablation area were defined for 1996 with a handheld Global Positioning System survey of 126 locations spread out over about 4 kilometers on the lower glacier margin. From 1949 to 1996, the terminus retreated about 1,650 meters for an average retreat rate of 35 meters per year.

  11. Stratigraphic reconnaissance of the Middle Jurassic Red Glacier Formation, Tuxedni Group, at Red Glacier, Cook Inlet, Alaska

    USGS Publications Warehouse

    LePain, David L.; Stanley, Richard G.

    2015-01-01

    The Alaska Division of Geological & Geophysical Surveys (DGGS) and U.S. Geological Survey (USGS) are implementing ongoing programs to characterize the petroleum potential of Cook Inlet basin. Since 2009 this program has included work on the Mesozoic stratigraphy of lower Cook Inlet, including the Middle Jurassic Tuxedni Group between Tuxedni and Iniskin bays (LePain and others, 2013; Stanley and others, 2013; fig. 5-1). The basal unit in the group, the Red Glacier Formation (fig. 5-2), is thought to be the principal source rock for oil produced in upper Cook Inlet, and available geochemical data support this contention (Magoon and Anders, 1992; Magoon, 1994). Despite its economic significance very little has been published on the formation since Detterman and Hartsock’s (1966) seminal contribution on the geology of the Iniskin–Tuxedni area nearly 50 years ago. Consequently its stratigraphy, contact relations with bounding formations, and source rock characteristics are poorly known. During the 2014 field season, a nearly continuous stratigraphic section through the Red Glacier Formation in its type area at Red Glacier was located and measured to characterize sedimentary facies and to collect a suite of samples for analyses of biostratigraphy, Rock-Eval pyrolysis, vitrinite reflectance, and sandstone composition (fig. 5-3).The poorly known nature of the Red Glacier Formation is likely due to its remote location, steep terrain, and the fact that the type section is split into two segments that are more than 3 km apart. The lower 375 m segment of the formation is on the ridge between Red Glacier and Lateral Glacier and the upper 1,009 m segment is on the ridge between Red Glacier and Boulder Creek (fig. 5-3). Structural complications in the area add to the difficulty in understanding how these two segments fit together.

  12. Role of Non-Precipitation Sources in Regulating the River Hydrology of a Himalayan Catchment

    NASA Astrophysics Data System (ADS)

    Grover, S.; Tayal, S.; Beldring, S.

    2017-12-01

    Hydrology of mountain catchments in Himalayas is strongly regulated by snow/ ice melt. Chenab basin of Himalayas is a snow and glacier fed basin, which makes it perennial and an important source of sustenance for downstream community. It is important to understand the variability in contribution from various sources to the water balance of catchment. Indirect assessment techniques are important to make such an assessment about the runoff patterns especially in data-scarce basins like Chenab. To analyze runoff patterns and contribution from different sources, we applied combination of semi-distributed HBV model and water balance approach for the period between 1971-2007. It was found that the contribution from non-precipitation sources to the total outflow in this region ranged from 30-70% with approximately 30% from glacier ice melt, and base-flow contributing around 20% to annual water-balance. Least precipitation year of 1977 shows maximum contribution from other sources, but also recorded the least outflow in catchment. Seasonal variation of the contribution from glacier ice melt was also estimated and in the months of May and June around 44% of the contribution to the outflow is from glacier melt only. Hydrological balance of the basin is positive during winters with outflow being very less than the inflow of water through precipitation or melt. Melt season starts in March but peaks during May and June with cryospheric contribution being almost twice the base flow contribution. Melting starts receding slowly after September, with its contribution to the outflow declining much below the baseflow contribution in October and November, when base-flow provides around 65% of water to the basin's outflow. Long term (1951-2010) temperature and precipitation data for the higher reaches of the basin indicates a warming trend (0.02 0C yr-1) and a decline in annual precipitation. But on a basin scale, precipitation is increasing and the non-precipitation contribution from

  13. Evaluate ERTS imagery for mapping and detection of changes of snowcover on land and on glaciers

    NASA Technical Reports Server (NTRS)

    Meier, M. F. (Principal Investigator)

    1973-01-01

    The author has identified the following significant results. The area of snow cover on land was determined from ERTS-1 imagery. Snow cover in specific drainage basins was measured with the Stanford Research Institute console by electronically superimposing basin outlines on imagery, with video density slicing to measure areas. Snow covered area and snowline altitudes were also determined by enlarging ERTS-1 imagery 1:250,000 and using a transparent map overlay. Under very favorable conditions, snowline altitude was determined to an accuracy of about 60 m. Ability to map snow cover or to determine snowline altitude depends primarily on cloud cover and vegetation and secondarily on slope, terrain roughness, sun angle, radiometric fidelity, and amount of spectral information available. Glacier accumulation area ratios were determined from ERTS-1 imagery. Also, subtle flow structures, undetected on aerial photographs, were visible. Surging glaciers were identified, and the changes resulting from the surge of a large glacier were measured as were changes in tidal glacier termini.

  14. Fluctuations of a Temperate Mountain Glacier in Response to Climate Change

    NASA Astrophysics Data System (ADS)

    Bachmann, M.; Bidlake, W.

    2012-12-01

    Glacier mass balance is a fundamental parameter for understanding and predicting the evolution of glaciers on the landscape in response to climate change. The USGS Ice and Climate Project (ICP) continues to extend the longest-running USGS benchmark glacier mass-balance record at South Cascade Glacier, Washington. Due to the importance of South Cascade Glacier data sets for glaciological and climate research, ICP is releasing decades-old previously unpublished glacier surface and bed maps, mass balance data at individual sites, ice velocity data, and an updated ice inventory for the surrounding basin. The complete record includes a pre-Industrial Revolution reconstruction of the glacier and seasonal mass balance measurements for the past 54 years (1958-2012). Since 2000, the glacier has experienced four of the five most negative summer balances and two of the largest positive accumulation years, indicating that the glacier is continuing to respond to recent warming and precipitation changes. Recently, ICP has developed a temperature-index glacier melt model that extrapolates daily accumulation and melt rates from intermittent field observations based on regional meteorological data, and an expert system for mass balance that captures the strengths of both measurement and modeling for assessing mass balance. The models have been successfully calibrated at South Cascade Glacier, where ample observations are available, but are designed to be used with as few or as many glaciological field data as are available for a given ice mass.

  15. Evaluation of methodologies for interpolation of data for hydrological modeling in glacierized basins with limited information

    NASA Astrophysics Data System (ADS)

    Muñoz, Randy; Paredes, Javier; Huggel, Christian; Drenkhan, Fabian; García, Javier

    2017-04-01

    The availability and consistency of data is a determining factor for the reliability of any hydrological model and simulated results. Unfortunately, there are many regions worldwide where data is not available in the desired quantity and quality. The Santa River basin (SRB), located within a complex topographic and climatic setting in the tropical Andes of Peru is a clear example of this challenging situation. A monitoring network of in-situ stations in the SRB recorded series of hydro-meteorological variables which finally ceased to operate in 1999. In the following years, several researchers evaluated and completed many of these series. This database was used by multiple research and policy-oriented projects in the SRB. However, hydroclimatic information remains limited, making it difficult to perform research, especially when dealing with the assessment of current and future water resources. In this context, here the evaluation of different methodologies to interpolate temperature and precipitation data at a monthly time step as well as ice volume data in glacierized basins with limited data is presented. The methodologies were evaluated for the Quillcay River, a tributary of the SRB, where the hydro-meteorological data is available from nearby monitoring stations since 1983. The study period was 1983 - 1999 with a validation period among 1993 - 1999. For temperature series the aim was to extend the observed data and interpolate it. Data from Reanalysis NCEP was used to extend the observed series: 1) using a simple correlation with multiple field stations, or 2) applying the altitudinal correction proposed in previous studies. The interpolation then was applied as a function of altitude. Both methodologies provide very close results, by parsimony simple correlation is shown as a viable choice. For precipitation series, the aim was to interpolate observed data. Two methodologies were evaluated: 1) Inverse Distance Weighting whose results underestimate the amount

  16. Alpine glacier change in the Eastern Altun mountains of Northwest China during 1972-2010.

    PubMed

    Yu, Xinyang; Lu, Changhe

    2015-01-01

    Accurately mapping and monitoring glacier changes over decades is important for providing information to support sustainable use of water resource in arid regions of northwest China. Since 1970, glaciers in the Eastern Altun Mountains showed remarkable recession. Further study is indispensable to indicate the extent and amplitude of glacial change at basin and individual glacier scale. In this study, spatiotemporal glacier changes referring to the year 1972, 1990, 2000 and 2010 were studied for the Eastern Altun Mountains using Landsat MSS/TM/ETM+ images and glacier volume-area scaling. The results demonstrated that the total area and volume of glaciers in EAMs decreased significantly by 10.70±0.57 km² (19.56±10.41%) and 0.61±0.03 km³ (23.19±11.40%) during 1972-2010, respectively. More than half of the total receding area occurred during 1990-2000, primarily due to higher temperature increasing. However, varied response of individual glaciers indicated that glacier change was also affected by glacier dynamics, which was related to local topography. In addition, five glaciers unrecorded in the glacier inventory of China were reported in this study.

  17. Alpine Glacier Change in the Eastern Altun Mountains of Northwest China during 1972-2010

    PubMed Central

    Yu, Xinyang; Lu, Changhe

    2015-01-01

    Accurately mapping and monitoring glacier changes over decades is important for providing information to support sustainable use of water resource in arid regions of northwest China. Since 1970, glaciers in the Eastern Altun Mountains showed remarkable recession. Further study is indispensable to indicate the extent and amplitude of glacial change at basin and individual glacier scale. In this study, spatiotemporal glacier changes referring to the year 1972, 1990, 2000 and 2010 were studied for the Eastern Altun Mountains using Landsat MSS/TM/ETM+ images and glacier volume-area scaling. The results demonstrated that the total area and volume of glaciers in EAMs decreased significantly by 10.70±0.57 km² (19.56±10.41%) and 0.61±0.03 km³ (23.19±11.40%) during 1972–2010, respectively. More than half of the total receding area occurred during 1990–2000, primarily due to higher temperature increasing. However, varied response of individual glaciers indicated that glacier change was also affected by glacier dynamics, which was related to local topography. In addition, five glaciers unrecorded in the glacier inventory of China were reported in this study. PMID:25723669

  18. Gulkana Glacier, Alaska-Mass balance, meteorology, and water measurements, 1997-2001

    USGS Publications Warehouse

    March, Rod S.; O'Neel, Shad

    2011-01-01

    The measured winter snow, maximum winter snow, net, and annual balances for 1997-2001 in the Gulkana Glacier basin are determined at specific points and over the entire glacier area using the meteorological, hydrological, and glaciological data. We provide descriptions of glacier geometry to aid in estimation of conventional and reference surface mass balances and descriptions of ice motion to aid in the understanding of the glacier's response to its changing geometry. These data provide annual estimates for area altitude distribution, equilibrium line altitude, and accumulation area ratio during the study interval. New determinations of historical area altitude distributions are given for 1900 and annually from 1966 to 2001. As original weather instrumentation is nearing the end of its deployment lifespan, we provide new estimates of overlap comparisons and precipitation catch efficiency. During 1997-2001, Gulkana Glacier showed a continued and accelerated negative mass balance trend, especially below the equilibrium line altitude where thinning was pronounced. Ice motion also slowed, which combined with the negative mass balance, resulted in glacier retreat under a warming climate. Average annual runoff augmentation by glacier shrinkage for 1997-2001 was 25 percent compared to the previous average of 13 percent, in accordance with the measured glacier volume reductions.

  19. Study on the contribution of cryosphere to runoff in the cold alpine basin: A case study of Hulugou River Basin in the Qilian Mountains

    NASA Astrophysics Data System (ADS)

    Zongxing, Li; Qi, Feng; Wei, Liu; Tingting, Wang; Aifang, Cheng; Yan, Gao; Xiaoyan, Guo; Yanhui, Pan; Jianguo, Li; Rui, Guo; Bing, Jia

    2014-11-01

    Global warming would inevitably lead to the increased glacier-snow meltwater and mountainous discharge. Taking an example the Hulugou River Basin in the Qilian Mountains, this study confirmed the contribution of cryosphere to runoff by means of the isotope hydrograph separation. The hydro-geochemistry and the isotope geochemistry suggested that both the meltwater and rainwater infiltrated into the subsurface and fed into the river runoff of the Hulugou River Basin in the form of springs. The isotopic composition of river water and underground water was close to the Local Meteoric Water Line, and the δ18O and δD ranged among precipitation, glacier-snow meltwater and frozen soil meltwater. The results indicated that 68% of the recharge of the Hulugou River water was the precipitation, thereinto, glacier-snow meltwater and frozen soil meltwater contributing 11% and 21%, respectively. For tributary-1, precipitation accounted for 77% of the total stream runoff, with frozen soil meltwater accounting for 17%, and glacier-snow meltwater only supplied 6%. During the sampling period, the contribution of surface runoff from precipitation was 44% to tributary-2, and glacier-snow meltwater had contributed 42%; only 14% from frozen soil meltwater. For tributary-3, precipitation accounted for 63% of the total runoff, and other 37% originated from the frozen soil meltwater. According to the latest observational data, the glacier-snow meltwater has accounted for 11.36% of the total runoff in the stream outlet, in which the calculation has been verified by hydrograph separation. It is obvious that the contribution of cryosphere has accounted for 1/3 of the outlet runoff in the Hulugou River Basin, which has been an important part of river sources. This study demonstrated that the alpine regions of western China, especially those basins with glaciers, snow and frozen soil, have played a crucial role in regional water resource provision under global warming.

  20. Glacial history and runoff components of the Tlikakila River Basin, Lake Clark National Park and Preserve, Alaska

    USGS Publications Warehouse

    Brabets, Timothy P.; March, Rod S.; Trabant, Dennis C.

    2004-01-01

    The Tlikakila River is located in Lake Clark National Park and Preserve and drains an area of 1,610 square kilometers (622 square miles). Runoff from the Tlikakila River Basin accounts for about one half of the total inflow to Lake Clark. Glaciers occupy about one third of the basin and affect the runoff characteristics of the Tlikakila River. As part of a cooperative study with the National Park Service, glacier changes and runoff characteristics in the Tlikakila River Basin were studied in water years 2001 and 2002. Based on analyses of remote sensing data and on airborne laser profiling, most glaciers in the Tlikakila River Basin have retreated and thinned from 1957 to the present. Volume loss from 1957-2001 from the Tanaina Glacier, the largest glacier in the Tlikakila River Basin, was estimated to be 6.1 x 109 cubic meters or 1.4 x 108 cubic meters per year. For the 2001 water year, mass balance measurements made on the three largest glaciers in the Tlikakila River BasinTanaina, Glacier Fork, and North Forkall indicate a negative mass balance. Runoff measured near the mouth of the Tlikakila River for water year 2001 was 1.70 meters. Of this total, 0.18 meters (11 percent) was from glacier ice melt, 1.27 meters (75 percent) was from snowmelt, 0.24 meters (14 percent) was from rainfall runoff, and 0.01 meters (1 percent) was from ground water. Although ground water is a small component of runoff, it provides a critical source of warm water for fish survival in the lower reaches of the Tlikakila River.

  1. A Mini-Surge on theRyder Glacier, Greenland Observed via Satelite Radar Interferometry

    NASA Technical Reports Server (NTRS)

    Joughin, I.; Tulaczyk, S.; Fahnestock, M.; Kwok, R.

    1996-01-01

    A dramatic short term speed up of the Ryder glacier has been detected using satellite radar interferometry. The accelerated flow represents a substantial, though short-lived, change in the ice discharge from this basin. We believe that meltwater was involved in this event, either as an active participant, as meltwater-filled lakes on the surface of the glacier drained during the period of rapid motion.

  2. Area and Elevation Changes of a Debris-Covered Glacier and a Clean-Ice Glacier Between 1952-2013 Using Aerial Images and Structure-from-Motion

    NASA Astrophysics Data System (ADS)

    Lardeux, P.; Glasser, N. F.; Holt, T.; Irvine-Fynn, T. D.; Hubbard, B. P.

    2015-12-01

    Since 1952, the clean-ice Glacier Blanc has retreated twice as fast as the adjacent debris-covered Glacier Noir. Located in the French Alps and separated by only 1 km, both glaciers experience the same climatic conditions, making them ideal to evaluate the impact of debris cover on glacier evolution. We used aerial photographs from 16 acquisitions from 1952 to 2013 to reconstruct and analyze glacier elevation changes using Structure-from-Motion (SfM) techniques. Here, we present the process of developing sub-metric resolution digital elevation models (DEMs) from these aerial photographs. By combining 16 DEMs, we produced a dataset of elevation changes of Glacier Noir and Glacier Blanc, including time-series analysis of lateral and longitudinal profiles, glacier hypsometry and mass balance variation. Our preliminary results indicate that Glacier Noir and Glacier Blanc have both thinned to a similar magnitude, ≤ 20 m, despite a 1 km retreat for Glacier Blanc and only 500 m for Glacier Noir. However, these elevation change reconstructions are hampered by large uncertainties, principally due to the lack of independent camera calibration on the historical imagery. Initial attempts using posteriori correction grids have proven to significantly increase the accuracy of these data. We will present some of the uncertainties and solutions linked to the use of SfM on such a large scale and on such an old dataset. This study demonstrates how SfM can be used to investigate long-term trends in environmental change, allowing glacier monitoring to be up-scaled. It also highlights the need for on-going validation of methods to increase the accuracy and precision of SfM in glaciology. This work is not only advancing our understanding of the role of the debris layer, but will also aid glacial geology more generally with, for example, detailed geomorphological analysis of proglacial terrain and Quaternary sciences with quick and accurate reconstruction of a glacial paleo-environment.

  3. Latitudinal variation of sedimentation and erosion rates from Patagonia and Antarctic Peninsula tidewater glaciers (46°-65° S)

    NASA Astrophysics Data System (ADS)

    Fernandez-Vasquez, R. A.; Anderson, J. B.; Wellner, J. S.; Minzoni, R. L.

    2012-12-01

    We present the results of the study of tidewater glacier depositional basins, across a broad latitudinal transect from central Patagonia (46°S) to the Antarctic Peninsula (65°S). Based on sediment cores and seismic records, we estimate accumulation rates at several timescales as well as sediment-volume derived erosion rates (Er) for millennial time scales. In the Antarctic Peninsula, accumulation rates are ~100 mm/yr for centennial and millennial timescales. In Patagonia, proximal basins are in general well isolated and have short timescale (decadal-centennial) sedimentary records and high accumulation rates, whereas medial (more distal) basins have millennial scale sedimentary records and low accumulation rates. We hypothesize that the "Saddler effect" in the accumulation rates of the Patagonian study areas exists because Neoglacial advance and recent post-Little Ice Age retreat has left well isolated proximal basins that effectively trap sediments. This, along with high sediment yields, produces high decadal accumulation rates. There is no such organization of basins in the Antarctic Peninsula fjords and bays and no such clear manifestation of Neoglacial advances or morphologies. Erosion rates span two orders of magnitude from 0.03 mm/yr for Lapeyrère Bay at Anvers Island, Antarctica (~64.5°S), to 1.09 mm/yr for San Rafael Glacier in northern Patagonia (~46.5°S). Rates for Antarctic Peninsula glaciers are in general lower than those of temperate Patagonian glaciers. A good correlation of erosion rates and modern sea level annual temperature was found. A latitudinal decrease in millennial erosion rates is interpreted as a result of decreasing annual temperature although decreasing annual precipitation may also be a factor. However, local variability within each region might be influenced by differences in bedrock geology (e.g. Herbert Sound versus Lapeyrère and Andvord bays ) and drainage basin morphology (hypsometry, number of glaciers and length of overall

  4. Climate Change and Glacier Retreat: Scientific Fact and Artistic Opportunity

    NASA Astrophysics Data System (ADS)

    Fagre, D. B.

    2008-12-01

    Mountain glaciers continue to retreat rapidly over most of the globe. In North America, at Glacier National Park, Montana, recent research results from Sperry Glacier (2005-2007) indicate negative mass balances are now 3-4 times greater than in the 1950s. A geospatial model of glacier retreat in the Blackfoot-Jackson basin suggested all glaciers would be gone by 2030 but has proved too conservative. Accelerated glacier shrinkage since the model was developed has mirrored an increase in actual annual temperature that is almost twice the rate used in the model. The glaciers in Glacier National Park are likely to be gone well before 2030. A variety of media, curricula, and educational strategies have been employed to communicate the disappearance of the glaciers as a consequence of global warming. These have included everything from print media and television coverage to podcasts and wayside exhibits along roads in the park. However, a new thrust is to partner with artists to communicate climate change issues to new audiences and through different channels. A scientist-artist retreat was convened to explore the tension between keeping artistic products grounded in factually-based reality while providing for freedom to express artistic creativity. Individual artists and scientists have worked to create aesthetic and emotional images, using painting, poetry, music and photography, to convey core messages from research on mountain ecosystems. Finally, a traveling art exhibit was developed to highlight the photography that systematically documents glacier change through time. The aim was to select photographs that provide the most compelling visual experience for an art-oriented viewer and also accurately reflect the research on glacier retreat. The exhibit opens on January 11, 2009

  5. Sedimentary petrology and reservoir quality of the Middle Jurassic Red Glacier Formation, Cook Inlet forearc basin: Initial impressions

    USGS Publications Warehouse

    Helmold, K.P.; LePain, D.L.; Stanley, Richard G.

    2016-01-01

    The Division of Geological & Geophysical Surveys and Division of Oil & Gas are currently conducting a study of the hydrocarbon potential of Cook Inlet forearc basin (Gillis, 2013, 2014; LePain and others, 2013; Wartes, 2015; Herriott, 2016 [this volume]). The Middle Jurassic Tuxedni Group is recognized as a major source of oil in Tertiary reservoirs (Magoon, 1994), although the potential for Tuxedni reservoirs remains largely unknown. As part of this program, five days of the 2015 field season were spent examining outcrops, largely sandstones, of the Middle Jurassic Red Glacier Formation (Tuxedni Group) approximately 6.4 km northeast of Johnson Glacier on the western side of Cook Inlet (fig. 4-1). Three stratigraphic sections (fig. 4-2) totaling approximately 307 m in thickness were measured and described in detail (LePain and others, 2016 [this volume]). Samples were collected for a variety of analyses including palynology, Rock-Eval pyrolysis, vitrinite reflectance, detrital zircon geochronology, and petrology. This report summarizes our initial impressions of the petrology and reservoir quality of sandstones encountered in these measured sections. Interpretations are based largely on hand-lens observations of hand specimens and are augmented by stereomicroscope observations. Detailed petrographic (point-count) analyses and measurement of petrophysical properties (porosity, permeability, and grain density) are currently in progress.

  6. Changes in the Surface Area of Glaciers in Northern Eurasia

    NASA Astrophysics Data System (ADS)

    Khromova, T.; Nosenko, G.

    2012-12-01

    Glaciers are widely recognized as key indicators of climate change. Recent evidence suggests an acceleration of glacier mass loss in several key mountain regions. Glacier recession implies the landscape changes in the glacial zone, origin of new lakes and activation of natural disaster processes, catastrophic mudflows, ice avalanches, outburst floods, and etc. The presence of glaciers in itself threats to human life, economic activity and growing infrastructure. Economical and recreational human activity in mountain regions requires relevant information on snow and ice objects. Absence or inadequacy of such information results in financial and human losses. A more comprehensive evaluation of glacier changes is imperative to assess ice contributions to global sea level rise and the future of water resources from glacial basins. One of the urgent steps is a full inventory of all ice bodies, their volume and changes The first estimation of glaciers state and glaciers distribution in the big part of Northern Eurasia has been done in the USSR Glacier Inventory published in 1966 -1980 as a part of IHD activity. The Inventory is based on topographic maps and air photos and reflects the status of the glaciers in 1957-1970y. There is information about 23796 glaciers with area of 78222.3 km2 in the Inventory. It covers 23 glacier systems on Northern Eurasia. In the 80th the USSR Glacier Inventory has been transformed in the digital form as a part of the World Glacier Inventory. Recent satellite data provide a unique opportunity to look again at these glaciers and to evaluate changes in glacier extent for the second part of XX century. In the paper we report about 15 000 glaciers outlines for Caucasus, Pamir, Tien-Shan, Altai, Syntar-Khayata, Cherskogo Range, Kamchatka and Russian Arctic which have been derived from ASTER and Landsat imagery and could be used for glacier changes evaluation. The results show that glaciers are retreating in all these regions. There is, however

  7. Review article: Hydrological modeling in glacierized catchments of central Asia - status and challenges

    NASA Astrophysics Data System (ADS)

    Chen, Yaning; Li, Weihong; Fang, Gonghuan; Li, Zhi

    2017-02-01

    Meltwater from glacierized catchments is one of the most important water supplies in central Asia. Therefore, the effects of climate change on glaciers and snow cover will have increasingly significant consequences for runoff. Hydrological modeling has become an indispensable research approach to water resources management in large glacierized river basins, but there is a lack of focus in the modeling of glacial discharge. This paper reviews the status of hydrological modeling in glacierized catchments of central Asia, discussing the limitations of the available models and extrapolating these to future challenges and directions. After reviewing recent efforts, we conclude that the main sources of uncertainty in assessing the regional hydrological impacts of climate change are the unreliable and incomplete data sets and the lack of understanding of the hydrological regimes of glacierized catchments of central Asia. Runoff trends indicate a complex response to changes in climate. For future variation of water resources, it is essential to quantify the responses of hydrologic processes to both climate change and shrinking glaciers in glacierized catchments, and scientific focus should be on reducing uncertainties linked to these processes.

  8. Increased Ocean Access to Totten Glacier, East Antarctica

    NASA Astrophysics Data System (ADS)

    Blankenship, D. D.; Greenbaum, J. S.; Young, D. A.; Richter, T. G.; Roberts, J. L.; Aitken, A.; Legresy, B.; Warner, R. C.; van Ommen, T. D.; Siegert, M. J.

    2015-12-01

    The Totten Glacier is the largest ice sheet outlet in East Antarctica, draining 3.5 meters of eustatic sea level potential from the Aurora Subglacial Basin (ASB) into the Sabrina Coast. Recent work has shown that the ASB has drained and filled many times since largescale glaciation began including evidence that it collapsed during the Pliocene. Steady thinning rates observed near Totten Glacier's grounding line since the beginning of the satellite altimetry record are the largest in East Antarctica and the nature of the thinning suggests that it is driven by enhanced basal melting due to ocean processes. Warm Modified Circumpolar Deep Water (MCDW), which has been linked to glacier retreat in West Antarctica, has been observed in summer and winter on the Sabrina Coast continental shelf in the 400-500 m depth range. Using airborne geophysical data acquired over multiple years we delineate seafloor valleys connecting the inner continental shelf to the cavity beneath Totten Glacier that cut through a large sill centered along the ice shelf calving front. The sill shallows to depths of about 300 mbsl and was likely a grounding line pinning point during Holocene retreat, however, the two largest seafloor valleys are deeper than the observed range of thermocline depths. The deeper of the two valleys, a 4 km-wide trough, connects to the ice shelf cavity through an area of the coastline that was previously believed to be grounded but that our analysis demonstrates is floating, revealing a second, deeper entryway to ice shelf cavity. The previous coastline was charted using satellite-based mapping techniques that infer subglacial properties based on surface expression and behavior; the new geophysical analysis techniques we use enable inferences of subglacial characteristics using direct observations of the ice-water interface. The results indicate that Totten Glacier and, by extension, the Aurora Subglacial Basin are vulnerable to MCDW that has been observed on the nearby

  9. Recent thinning of Bowdoin Glacier, a marine terminating outlet glacier in northwestern Greenland

    NASA Astrophysics Data System (ADS)

    Tsutaki, S.; Sugiyama, S.; Sakakibara, D.; Sawagaki, T.; Maruyama, M.

    2014-12-01

    Ice discharge from calving glaciers has increased in the Greenland ice sheet (GrIS), and this increase plays important roles in the volume change of GrIS and its contribution to sea level rise. Thinning of GrIS calving glaciers has been studied by the differentiation of digital elevation models (DEMs) derived by satellite remote-sensing (RS). Such studies rely on the accuracy of DEMs, but calibration of RS data with ground based data is difficult. This is because field data on GrIS calving glaciers are few. In this study, we combined field and RS data to measure surface elevation change of Bowdoin Glacier, a marine terminating outlet glacier in northwestern Greenland (77°41'18″N, 68°29'47″W). The fast flowing part of the glacier is approximately 3 km wide and 10 km long. Ice surface elevation within 6 km from the glacier terminus was surveyed in the field in July 2013 and 2014, by using the global positioning system. We also measured the surface elevation over the glacier on August 20, 2007 and September 4, 2010, by analyzing Advanced Land Observing Satellite (ALOS), Panchromatic remote-sensing Instrument for Stereo Mapping (PRISM) images. We calibrated the satellite derived elevation data with our field measurements, and generated DEM for each year with a 25 m grid mesh. The field data and DEMs were compared to calculate recent glacier elevation change. Mean surface elevation change along the field survey profiles were -16.3±0.2 m (-5.3±0.1 m yr-1) in 2007-2010 and -10.8±0.2 m (-3.8±0.1 m yr-1) in 2010-2013. These rates are much greater than those observed on non-calving ice caps in the region, and similar to those reported for other calving glaciers in northwestern Greenland. Loss of ice was greater near the glacier terminus, suggesting the importance of ice dynamics and/or interaction with the ocean.

  10. Glaciers of North America - Glaciers of Alaska

    USGS Publications Warehouse

    Molnia, Bruce F.

    2008-01-01

    Glaciers cover about 75,000 km2 of Alaska, about 5 percent of the State. The glaciers are situated on 11 mountain ranges, 1 large island, an island chain, and 1 archipelago and range in elevation from more than 6,000 m to below sea level. Alaska's glaciers extend geographically from the far southeast at lat 55 deg 19'N., long 130 deg 05'W., about 100 kilometers east of Ketchikan, to the far southwest at Kiska Island at lat 52 deg 05'N., long 177 deg 35'E., in the Aleutian Islands, and as far north as lat 69 deg 20'N., long 143 deg 45'W., in the Brooks Range. During the 'Little Ice Age', Alaska's glaciers expanded significantly. The total area and volume of glaciers in Alaska continue to decrease, as they have been doing since the 18th century. Of the 153 1:250,000-scale topographic maps that cover the State of Alaska, 63 sheets show glaciers. Although the number of extant glaciers has never been systematically counted and is thus unknown, the total probably is greater than 100,000. Only about 600 glaciers (about 1 percent) have been officially named by the U.S. Board on Geographic Names (BGN). There are about 60 active and former tidewater glaciers in Alaska. Within the glacierized mountain ranges of southeastern Alaska and western Canada, 205 glaciers (75 percent in Alaska) have a history of surging. In the same region, at least 53 present and 7 former large ice-dammed lakes have produced jokulhlaups (glacier-outburst floods). Ice-capped volcanoes on mainland Alaska and in the Aleutian Islands have a potential for jokulhlaups caused by subglacier volcanic and geothermal activity. Because of the size of the area covered by glaciers and the lack of large-scale maps of the glacierized areas, satellite imagery and other satellite remote-sensing data are the only practical means of monitoring regional changes in the area and volume of Alaska's glaciers in response to short- and long-term changes in the maritime and continental climates of the State. A review of the

  11. Global Monitoring of Mountain Glaciers Using High-Resolution Spotlight Imaging from the International Space Station

    NASA Astrophysics Data System (ADS)

    Donnellan, A.; Green, J. J.; Bills, B. G.; Goguen, J.; Ansar, A.; Knight, R. L.; Hallet, B.; Scambos, T. A.; Thompson, L. G.; Morin, P. J.

    2013-12-01

    Mountain glaciers around the world are retreating rapidly, contributing about 20% to present-day sea level rise. Numerous studies have shown that mountain glaciers are sensitive to global environmental change. Temperate-latitude glaciers and snowpack provide water for over 1 billion people. Glaciers are a resource for irrigation and hydroelectric power, but also pose flood and avalanche hazards. Accurate mass balance assessments have been made for only 280 glaciers, yet there are over 130,000 in the World Glacier Inventory. The rate of glacier retreat or advance can be highly variable, is poorly sampled, and inadequately understood. Liquid water from ice front lakes, rain, melt, or sea water and debris from rocks, dust, or pollution interact with glacier ice often leading to an amplification of warming and further melting. Many mountain glaciers undergo rapid and episodic events that greatly change their mass balance or extent but are sparsely documented. Events include calving, outburst floods, opening of crevasses, or iceberg motion. Spaceborne high-resolution spotlight optical imaging provides a means of clarifying the relationship between the health of mountain glaciers and global environmental change. Digital elevation models (DEMs) can be constructed from a series of images from a range of perspectives collected by staring at a target during a satellite overpass. It is possible to collect imagery for 1800 targets per month in the ×56° latitude range, construct high-resolution DEMs, and monitor changes in high detail over time with a high-resolution optical telescope mounted on the International Space Station (ISS). Snow and ice type, age, and maturity can be inferred from different color bands as well as distribution of liquid water. Texture, roughness, albedo, and debris distribution can be estimated by measuring bidirectional reflectance distribution functions (BRDF) and reflectance intensity as a function of viewing angle. The non-sun-synchronous orbit

  12. Mass balance, meteorological, ice motion, surface altitude, runoff, and ice thickness data at Gulkana Glacier, Alaska, 1995 balance year

    USGS Publications Warehouse

    March, Rod S.

    2000-01-01

    The 1995 measured winter snow, maximum winter snow, net, and annual balances in the Gulkana Glacier basin were evaluated on the basis of meteorological, hydrological, and glaciological data obtained in the basin. Averaged over the glacier, the measured winter snow balance was 0.94 meter on April 19, 1995, 0.6 standard deviation below the long-term average; the maximum winter snow balance, 0.94 meter, was reached on April 25, 1995; the net balance (from September 18, 1994 to August 29, 1995) was -0.70 meter, 0.76 standard deviation below the long-term average. The annual balance (October 1, 1994, to September 30, 1995) was -0.86 meter. Ice-surface motion and altitude changes measured at three index sites document seasonal ice speed and glacier-thickness changes. Annual stream runoff was 2.05 meters averaged over the basin, approximately equal to the long-term average. The 1976 ice-thickness data are reported from a single site near the highest measurement site (180 meters thick) and from two glacier cross profiles near the mid-glacier (270 meters thick on centerline) and low glacier (150 meters thick on centerline) measurement sites. A new area-altitude distribution determined from 1993 photogrammetry is reported. Area-averaged balances are reported from both the 1967 and 1993 area-altitude distribution so the reader may directly see the effect of the update. Briefly, loss of ablation area between 1967 and 1993 results in a larger weighting being applied to data from the upper glacier site and hence, increases calculated area-averaged balances. The balance increase is of the order of 15 percent for net balance.

  13. River piracy and drainage basin reorganization led by climate-driven glacier retreat

    NASA Astrophysics Data System (ADS)

    Shugar, Daniel H.; Clague, John J.; Best, James L.; Schoof, Christian; Willis, Michael J.; Copland, Luke; Roe, Gerard H.

    2017-04-01

    River piracy--the diversion of the headwaters of one stream into another one--can dramatically change the routing of water and sediment, with a profound effect on landscape evolution. Stream piracy has been investigated in glacial environments, but so far it has mainly been studied over Quaternary or longer timescales. Here we document how retreat of Kaskawulsh Glacier--one of Canada's largest glaciers--abruptly and radically altered the regional drainage pattern in spring 2016. We use a combination of hydrological measurements and drone-generated digital elevation models to show that in late May 2016, meltwater from the glacier was re-routed from discharge in a northward direction into the Bering Sea, to southward into the Pacific Ocean. Based on satellite image analysis and a signal-to-noise ratio as a metric of glacier retreat, we conclude that this instance of river piracy was due to post-industrial climate change. Rapid regional drainage reorganizations of this type can have profound downstream impacts on ecosystems, sediment and carbon budgets, and downstream communities that rely on a stable and sustained discharge. We suggest that the planforms of Slims and Kaskawulsh rivers will adjust in response to altered flows, and the future Kaskawulsh watershed will extend into the now-abandoned headwaters of Slims River and eventually capture the Kluane Lake drainage.

  14. Retreat and stagnation of Little Ice Age glaciers in Yosemite National Park

    NASA Astrophysics Data System (ADS)

    Stock, G. M.; Anderson, R. S.; Painter, T. H.

    2016-12-01

    The high peaks of Yosemite National Park in the Sierra Nevada, California, retain several small (<1 km2) glaciers formed during the Little Ice Age. The largest of these, the Lyell and Maclure glaciers, occupy the headwaters of the Tuolumne River and have been the subject of detailed scientific study since the late 19th century. We repeated historical photographs, field surveys, and velocity measurements on these glaciers to document their response to climate change. Field surveys and remote sensing data indicate that glacier surface areas have diminished by 67-78% since 1883, with 10% of that loss coinciding with the 2012-2015 California drought. The naturalist John Muir first measured the velocity of the Maclure Glacier in 1872, finding that the glacier moved about 2.6 cm/day during the late summer and early autumn. We reproduced Muir's measurements over the same seasonal period and found the glacier to be moving at the same rate, despite the marked reduction in surface area. Time-averaged velocities measured over a four-year period show strong seasonality, with rates near zero in winter. Much of the present movement of the Maclure Glacier must therefore occur as sliding at the bed, which is apparently enhanced by greater melt. The adjacent Lyell Glacier displayed virtually no movement over the same four-year time period, likely because it has thinned below a critical threshold; both glaciers have thinned by more than 40 m since 1932, with thinning up to 3 m/yr during the 2012-2015 drought. New remote sensing data collected as part of NASA's Airborne Snow Observatory project offer opportunities to measure glacier volume and mass balance changes from 2012 onward. Numerical modeling of glacier mass balance will help to predict the timing of complete glacier loss and to assess the associated hydrological impacts on downstream ecosystems.

  15. Application of the MAGIC model to the Glacier Lakes catchments

    Treesearch

    John O. Reuss

    1994-01-01

    The MAGIC model (Cosby et al. 1985, 1986) was calibrated for East and West Glacier Lakes, two adjacent high-altitude (3200 m- 3700 m) catchments in the Medicine Bow National Forest of southern Wyoming. This model uses catchment characteristics including weathering rates, soil chemical characteristics, hydrological parameters, and precipitation amounts and composition...

  16. Partitioning of the water budget in the main river basins in High Mountain Asia with GRACE, model output, and other observations.

    NASA Astrophysics Data System (ADS)

    Velicogna, I.; Ciraci, E.; Grogan, D. S.; Lammers, R. B.

    2017-12-01

    Access to freshwater is important as world populations grow, especially in High Mountain Asia, where glaciers are a significant component of the freshwater resources, particularly in summer. Glaciers are sensitive to climate perturbations and affected by climate change. Our understanding of the contribution of glacier runoff to specific watersheds, and projections of glacier runoff in a warming climate, are critical to inform decisions, management and policy development. Here, we quantify changes in glacier mass balance in HMA using GRACE data and determine their contribution to river basin hydrology. We use GRACE data to estimate the HMA glacier mass mas balance and compare the results with changes in total water storage (TWS) for the major watersheds in the HMA regions. We designed ad-hoc mascon configurations to calculate the upstream glacier change in mass balance and contribution to major river basins water supply, determined appropriate corrections and uncertainties for the signal and evaluated the results via comparison with the Water Balance Model (WBM) output and other data (re-analysis data and satellite-derived precipitation and evapotranspiration). Most of the glacier loss is from the Himalaya region (Himalaya, Hengduan Shan S and E Tibet), whereas the western sectors (E and W Tien Shan; and Hindu Kush, Karakoram, W Kunlun, Pamir, Hissar Alay) experienced smaller losses but with larger interannual variability driven by changes in the westerly-driven winter precipitation. For the Indus basin, to evaluate the glacier contribution to the total water budget, we examine the contribution of the upper basin to the lower basin TWS change. Over the Upper Indus basin, we find that the seasonal decline in total water storage between May and September averages 88 Gt during 2002-2012. TRMM cumulative precipitation amounts to 119 Gt, leaving a runoff and evapotranspiration component of 207 Gt. This estimate compares well with an estimate for the WBM modeled runoff of

  17. Distribution of oil and natural-gas wells in relation to ground-water flow systems in the Great Basin region of Nevada and Utah, and adjacent states

    USGS Publications Warehouse

    Schaefer, Donald H.

    1996-01-01

    This map publication is one of several in a series concerning various aspects of the ground-water hydrology of the Great Basin in Nevada, Utah, and adjacent States.  One report in the series describes the hydrogeologic framework of the Great Basin (Plume and Carlton, 1988).  Another shows the ground-water levels for the aquifer systems of the Great Basin (Thomas and others, 1986).  A third report in the series describes the regional ground-water flow patterns in the Great Basin (Harrill and others, 1988).

  18. Sea-floor drainage features of Cascadia Basin and the adjacent continental slope, northeast Pacific Ocean

    USGS Publications Warehouse

    Hampton, M.A.; Karl, Herman A.; Kenyon, Neil H.

    1989-01-01

    Sea-floor drainage features of Cascadia Basin and the adjacent continental slope include canyons, primary fan valleys, deep-sea valleys, and remnant valley segments. Long-range sidescan sonographs and associated seismic-reflection profiles indicate that the canyons may originate along a mid-slope escarpment and grow upslope by mass wasting and downslope by valley erosion or aggradation. Most canyons are partly filled with sediment, and Quillayute Canyon is almost completely filled. Under normal growth conditions, the larger canyons connect with primary fan valleys or deep-sea valleys in Cascadia Basin, but development of accretionary ridges blocks or re-routes most canyons, forcing abandonment of the associated valleys in the basin. Astoria Fan has a primary fan valley that connects with Astoria Canyon at the fan apex. The fan valley is bordered by parallel levees on the upper fan but becomes obscure on the lower fan, where a few valley segments appear on the sonographs. Apparently, Nitinat Fan does not presently have a primary fan valley; none of the numerous valleys on the fan connect with a canyon. The Willapa-Cascadia-Vancouver-Juan de Fuca deep-sea valley system bypasses the submarine fans and includes deeply incised valleys to broad shallow swales, as well as within-valley terraces and hanging-valley confluences. ?? 1989.

  19. Irrigation as a Potential Driver for Anomalous Glacier Behavior in High Mountain Asia

    NASA Astrophysics Data System (ADS)

    de Kok, Remco J.; Tuinenburg, Obbe A.; Bonekamp, Pleun N. J.; Immerzeel, Walter W.

    2018-02-01

    Many glaciers in the northwest of High Mountain Asia (HMA) show an almost zero or positive mass balance, despite the global trend of melting glaciers. This phenomenon is often referred to as the "Karakoram anomaly," although strongest positive mass balances can be found in the Kunlun Shan mountain range, northeast of the Karakoram. Using a regional climate model, in combination with a moisture-tracking model, we show that the increase in irrigation intensity in the lowlands surrounding HMA, particularly in the Tarim basin, can locally counter the effects of global warming on glaciers in Kunlun Shan, and parts of Pamir and northern Tibet, through an increase in summer snowfall and decrease in net radiance. Irrigation can thus affect the regional climate in a way that favors glacier growth, and future projections of glacier melt, which may impact millions of inhabitants surrounding HMA, will need to take into account predicted changes in irrigation intensity.

  20. Nanga Parbat Revisited: Glacier changes between the 1930s and 2010

    NASA Astrophysics Data System (ADS)

    Nüsser, M.; Schmidt, S.

    2012-04-01

    In contrast to the relatively well investigated glacier changes in the mountains of Europe and North America, very few investigations using repeat photography have been undertaken in the Himalayas and adjacent high mountain regions. The present study seeks to redress this by investigating glacier changes in the Nanga Parbat region (NW-Himalaya) using matched pairs of photographs. A comprehensive collection of historical landscape photographs, taken by members of the German Himalaya expeditions in 1934 and 1937, forms a valuable baseline data set for the area. Our own fieldwork in the 1990s (1992-1997), 2006, and 2010 made it possible to repeat a large number of these photographs from viewpoints identical to the earlier ones. The multi-temporal data allows for direct comparisons and illustrates glacier changes over a span of seventy years. For the purpose of change detection, we also integrate the topographic map of 1934, as well as multi-temporal and multi-scale satellite data (Corona, ASTER, Landsat and Quickbird). The multi-temporal comparison of images detects a complex pattern of glacier retreat and stability in the six glaciers investigated in the Rupal Valley, to the South of Nanga Parbat. Whereas the termini of some of these glaciers are relatively stable since 1934; others such as the Raikot Glacier on the north face of Nanga Parbat are characterized by great fluctuation and a terminus retreat of about 210 m over the last 70 years. The extent of down-wasting displays a similar variation between the different glaciers under investigation.

  1. Influence of aeolian activities on the distribution of microbial abundance in glacier ice

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Li, X.-K.; Si, J.; Wu, G.-J.; Tian, L.-D.; Xiang, S.-R.

    2014-10-01

    Microorganisms are continuously blown onto the glacier snow, and thus the glacial depth profiles provide excellent archives of microbial communities and climatic and environmental changes. However, it is uncertain about how aeolian processes that cause climatic changes control the distribution of microorganisms in the glacier ice. In the present study, microbial density, stable isotopic ratios, 18O / 16O in the precipitation, and mineral particle concentrations along the glacial depth profiles were collected from ice cores from the Muztag Ata glacier and the Dunde ice cap. The ice core data showed that microbial abundance was often, but not always associated with high concentrations of particles. Results also revealed clear seasonal patterning with high microbial abundance occurring in both the cooling autumn and warming spring-summer seasons. Microbial comparisons among the neighbouring glaciers display a heterogeneous spatial pattern, with the highest microbial cell density in the glaciers lying adjacent to the central Asian deserts and lowest microbial density in the southwestern margin of the Tibetan Plateau. In conclusion, microbial data of the glaciers indicates the aeolian deposits of microorganisms in the glacier ice and that the spatial patterns of microorgansisms are related to differences in sources of microbial flux and intensity of aeolian activities in the current regions. The results strongly support our hypothesis of aeolian activities being the main agents controlling microbial load in the glacier ice.

  2. Debris-Covered Glaciers in the Sierra Nevada, California, and Their Implications for Snowline Reconstructions

    USGS Publications Warehouse

    Clark, D.H.; Clark, M.M.; Gillespie, A.R.

    1994-01-01

    Ice-walled melt ponds on the surfaces of active valley-floor rock glaciers and Matthes (Little Ice Age) moraines in the southern Sierra Nevada indicate that most of these landforms consist of glacier ice under thin (ca. 1 - 10 m) but continuous covers of rock-fall-generated debris. These debris blankets effectively insulate the underlying ice and greatly reduce rates of ablation relative to that of uncovered ice. Such insulation explains the observations that ice-cored rock glaciers in the Sierra, actually debris-covered glaciers, are apparently less sensitive to climatic warming and commonly advance to lower altitudes than do adjacent bare-ice glaciers. Accumulation-area ratios and toe-to-headwall-altitude ratios used to estimate equilibrium-line altitudes (ELAs) of former glaciers may therefore yield incorrect results for cirque glaciers subject to abundant rockfall. Inadvertent lumping of deposits from former debris-covered and bare-ice glaciers partially explains an apparently anomalous regional ELA gradient reported for the pre-Matthes Recess Peak Neoglacial advance. Distinguishing such deposits may be important to studies that rely on paleo-ELA estimates. Moreover, Matthes and Recess Peak ELA gradients along the crest evidently depend strongly on local orographic effects rather than latitudinal climatic trends, indicating that simple linear projections and regional climatic interpretations of ELA gradients of small glaciers may be unreliable.

  3. Hydrogeochemical studies of historical mining areas in the Humboldt River basin and adjacent areas, northern Nevada

    USGS Publications Warehouse

    Nash, J. Thomas

    2005-01-01

    The study area comprises the Humboldt River Basin and adjacent areas, with emphasis on mining areas relatively close to the Humboldt River. The basin comprises about 16,840 mi2 or 10,800,000 acres. The mineral resources of the Humboldt Basin have been investigated by many scientists over the past 100 years, but only recently has our knowledge of regional geology and mine geology been applied to the understanding and evaluation of mining effects on water and environmental quality. The investigations reported here apply some of the techniques and perspectives developed in the Abandoned Mine Lands Initiative (AMLI) of the U.S. Geological Survey (USGS), a program of integrated geological-hydrological-biological-chemical studies underway in the Upper Animas River watershed in Colorado and the Boulder River watershed in, Montana. The goal of my studies of sites and districts is to determine the character of mining-related contamination that is actively or potentially a threat to water quality and to estimate the potential for natural attenuation of that contamination. These geology-based studies and recommendations differ in matters of emphasis and data collection from the biology-based assessments that are the cornerstone of environmental regulations.

  4. Future sea-level rise from tidewater and ice-shelf tributary glaciers of the Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Schannwell, C.; Barrand, N. E.; Radic, V.

    2016-12-01

    Iceberg calving and increased ice discharge from ice-shelf tributary glaciers contribute significant amounts to global sea-level rise (SLR) from the Antarctic Peninsula (AP). Owing to ongoing ice dynamical changes (collapse of buttressing ice shelves), these contributions have accelerated in recent years. As the AP is one of the fastest warming regions on Earth, further ice dynamical adjustment (increased ice discharge) is expected over the next two centuries. Here the first regional SLR projection of the AP from both iceberg calving and increased ice discharge from ice-shelf tributary glaciers in response to ice-shelf collapse is presented. The British Antarctic Survey Antarctic Peninsula Ice Sheet Model (BAS-APISM), previously shown to be suitable for the unique topographic setting from the AP, is forced by temperature output from 13 global climate models (GCMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5). In response to the high greenhouse gas emission scenario (Representative Concentration Pathway (RCP)8.5), simulations project contribution to SLR of 28±16 to 32±16 mm by 2300, partitioned approximately equally between contributions from tidewater glaciers and ice-shelf tributary glaciers. In the RCP4.5 scenario, sea-level rise projections to 2300 are dominated by tidewater glaciers ( ˜8-18 mm). In this cooler scenario, 2.4±1 mm is added to global sea levels from ice-shelf tributary drainage basins as fewer ice-shelves are projected to collapse. Sea-level projections from ice-shelf tributary glaciers are dominated by drainage basins feeding George VI Ice Shelf, accounting for ˜70% of simulated SLR. Combined total ice dynamical SLR projections to 2300 from the AP vary between 11±2 and 32±16 mm sea-level equivalent (SLE), depending on the emission scenario used. These simulations suggest that omission of tidewater glaciers could lead to a substantial underestimation of the ice-sheet's contribution to regional SLR. Iceberg calving and

  5. Contributions to Jarvis Creek Watershed, Alaska, from Winter Accumulation and Glacier Melt Inferred Through Airborne and Ground-Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Campbell, S. W.; Liljedahl, A. K.; Douglas, T. A.; Bernsen, S.; Gatesman, T.; Gerbi, C. C.

    2017-12-01

    Glacier meltwater contributions to river discharge has been increasing in much of the Arctic, likely because of higher air temperatures. For small glaciers that provide a large portion of meltwater to downstream discharge, a sustained negative mass balance is concerning to surrounding ecosystems because the water budget will ultimately decline when glacier ice disappears. Separating components of the hydrological budget is important for predicting future discharge, particularly when major inputs such as glacier ice melt are at risk of total loss. Jarvis Glacier in Eastern Alaska offers an example of this potential scenario. It is a 6-km long glacier that has been in retreat since the 1950's, yet it accounts for 15% of the annual downstream discharge into Jarvis Creek (Liljedahl et al., 2017). In March 2012 through April 2017 we completed yearly airborne and ground-penetrating radar surveys over Jarvis Glacier and its surrounding non-glaciated watershed. These surveys were conducted to assess winter snow accumulation and its potential contribution to the hydrological budget of Jarvis Creek. We also surveyed glacier ice thicknesses to estimate ice volume and potential long term future meltwater contributions to Jarvis Creek based on its sustained negative mass balance. High-frequency radar collected across Jarvis Glacier reveal winter accumulation rates between 1.1-1.9 m SWE. Thickness of winter snow in the surrounding glacier-free valleys is highly variable but it tended to accumulate as drifts near ridge tops or low in the valleys. Low-frequency GPR reveals ice thickness reaching 250 m, mid-glacier, tapering to less than 100 m near the debris-rich terminus. Several over-deepened basins exist and an obvious polythermal structure with 20-30 m of cold ice overlaying temperate ice is also evident. Our presentation will summarize further details of these results in relation to current and potential future contributions of glacier ice and winter snowpack melt to Jarvis

  6. Accelerating ice loss from the fastest Greenland and Antarctic glaciers

    NASA Astrophysics Data System (ADS)

    Thomas, R.; Frederick, E.; Li, J.; Krabill, W.; Manizade, S.; Paden, J.; Sonntag, J.; Swift, R.; Yungel, J.

    2011-05-01

    Ice discharge from the fastest glaciers draining the Greenland and Antarctic ice sheets - Jakobshavn Isbrae (JI) and Pine Island Glacier (PIG)- continues to increase, and is now more than double that needed to balance snowfall in their catchment basins. Velocity increase probably resulted from decreased buttressing from thinning (and, for JI, breakup) of their floating ice tongues, and from reduced basal drag as grounding lines on both glaciers retreat. JI flows directly into the ocean as it becomes afloat, and here creep rates are proportional to the cube of bed depth. Rapid thinning of the PIG ice shelf increases the likelihood of its breakup, and subsequent rapid increase in discharge velocity. Results from a simple model indicate that JI velocities should almost double to >20 km a-1 by 2015, with velocities on PIG increasing to >10 km a-1 after breakup of its ice shelf. These high velocities would probably be sustained over many decades as the glaciers retreat within their long, very deep troughs. Resulting sea-level rise would average about 1.5 mm a-1.

  7. Accelerating Ice Loss from the Fastest Greenland and Antarctic Glaciers

    NASA Technical Reports Server (NTRS)

    Thomas, R.; Frederick, E.; Li, J.; Krabill, W.; Manizade, S.; Paden, J.; Sonntag, J.; Swift, R.; Yungel, J.

    2011-01-01

    Ice discharge from the fastest glaciers draining the Greenland and Antarctic ice sheets . Jakobshavn Isbrae (JI) and Pine Island Glacier (PIG). continues to increase, and is now more than double that needed to balance snowfall in their catchment basins. Velocity increase probably resulted from decreased buttressing from thinning (and, for JI, breakup) of their floating ice tongues, and from reduced basal drag as grounding lines on both glaciers retreat. JI flows directly into the ocean as it becomes afloat, and here creep rates are proportional to the cube of bed depth. Rapid thinning of the PIG ice shelf increases the likelihood of its breakup, and subsequent rapid increase in discharge velocity. Results from a simple model indicate that JI velocities should almost double to >20 km/a by 2015, with velocities on PIG increasing to >10 km/a after breakup of its ice shelf. These high velocities would probably be sustained over many decades as the glaciers retreat within their long, very deep troughs. Resulting sea ]level rise would average about 1.5 mm/a.

  8. Grounding line processes on the Totten Glacier

    NASA Astrophysics Data System (ADS)

    Cook, S.; Watson, C. S.; Galton-Fenzi, B.; Peters, L. E.; Coleman, R.

    2017-12-01

    The Totten Glacier has been an area of recent interest due to its large drainage basin, much of which is grounded below sea level and has a history of large scale grounding line movement. Reports that warm water reaches the sub-ice shelf cavity have led to speculation that it could be vulnerable to future grounding line retreat. Over the Antarctic summer 2016/17 an array of 6 GPS and autonomous phase-sensitive radar (ApRES) units were deployed in the grounding zone of the Totten Glacier. These instruments measure changes in ice velocity and thickness which can be used to investigate both ice dynamics across the grounding line, and the interaction between ice and ocean in the subglacial cavity. Basal melt rates calculated from the ApRES units on floating ice range from 1 to 17 m/a. These values are significantly lower than previous estimates of basal melt rate produced by ocean modelling of the subglacial cavity. Meanwhile, GPS-derived velocity and elevation on the surface of the ice show a strong tidal signal, as does the vertical strain rate within the ice derived from internal layering from the ApRES instruments. These results demonstrate the significance of the complex grounding pattern of the Totten Glacier. The presence of re-grounding points has significant implications for the dynamics of the glacier and the ocean circulation within the subglacial cavity. We discuss what can be learned from our in situ measurements, and how they can be used to improve models of the glacier's future behaviour.

  9. Glaciers of Asia

    USGS Publications Warehouse

    Williams, Richard S.; Ferrigno, Jane G.

    2010-01-01

    This chapter is the ninth to be released in U.S. Geological Survey Professional Paper 1386, Satellite Image Atlas of Glaciers of the World, a series of 11 chapters. In each of the geographic area chapters, remotely sensed images, primarily from the Landsat 1, 2, and 3 series of spacecraft, are used to analyze the specific glacierized region of our planet under consideration and to monitor glacier changes. Landsat images, acquired primarily during the middle to late 1970s and early 1980s, were used by an international team of glaciologists and other scientists to study various geographic regions and (or) to discuss related glaciological topics. In each glacierized geographic region, the present areal distribution of glaciers is compared, wherever possible, with historical information about their past extent. The atlas provides an accurate regional inventory of the areal extent of glacier ice on our planet during the 1970s as part of a growing international scientific effort to measure global environmental change on the Earth?s surface. The chapter is divided into seven geographic parts and one topical part: Glaciers of the Former Soviet Union (F-1), Glaciers of China (F-2), Glaciers of Afghanistan (F?3), Glaciers of Pakistan (F-4), Glaciers of India (F-5), Glaciers of Nepal (F?6), Glaciers of Bhutan (F-7), and the Paleoenvironmental Record Preserved in Middle-Latitude, High-Mountain Glaciers (F-8). Each geographic section describes the glacier extent during the 1970s and 1980s, the benchmark time period (1972-1981) of this volume, but has been updated to include more recent information. Glaciers of the Former Soviet Union are located in the Russian Arctic and various mountain ranges of Russia and the Republics of Georgia, Kyrgyzstan, Tajikistan, and Kazakstun. The Glacier Inventory of the USSR and the World Atlas of Ice and Snow Resources recorded a total of 28,881 glaciers covering an area of 78,938 square kilometers (km2). China includes many of the mountain-glacier

  10. Best Merge Region Growing Segmentation with Integrated Non-Adjacent Region Object Aggregation

    NASA Technical Reports Server (NTRS)

    Tilton, James C.; Tarabalka, Yuliya; Montesano, Paul M.; Gofman, Emanuel

    2012-01-01

    Best merge region growing normally produces segmentations with closed connected region objects. Recognizing that spectrally similar objects often appear in spatially separate locations, we present an approach for tightly integrating best merge region growing with non-adjacent region object aggregation, which we call Hierarchical Segmentation or HSeg. However, the original implementation of non-adjacent region object aggregation in HSeg required excessive computing time even for moderately sized images because of the required intercomparison of each region with all other regions. This problem was previously addressed by a recursive approximation of HSeg, called RHSeg. In this paper we introduce a refined implementation of non-adjacent region object aggregation in HSeg that reduces the computational requirements of HSeg without resorting to the recursive approximation. In this refinement, HSeg s region inter-comparisons among non-adjacent regions are limited to regions of a dynamically determined minimum size. We show that this refined version of HSeg can process moderately sized images in about the same amount of time as RHSeg incorporating the original HSeg. Nonetheless, RHSeg is still required for processing very large images due to its lower computer memory requirements and amenability to parallel processing. We then note a limitation of RHSeg with the original HSeg for high spatial resolution images, and show how incorporating the refined HSeg into RHSeg overcomes this limitation. The quality of the image segmentations produced by the refined HSeg is then compared with other available best merge segmentation approaches. Finally, we comment on the unique nature of the hierarchical segmentations produced by HSeg.

  11. Modelling the contribution of supraglacial ice cliffs to the mass-balance of glaciers in the Langtang catchment, Nepalese Himalaya

    NASA Astrophysics Data System (ADS)

    Buri, P.; Steiner, J. F.; Miles, E.; Ragettli, S.; Pellicciotti, F.

    2017-12-01

    Supraglacial cliffs are typical surface features of debris-covered glaciers worldwide, affecting surface evolution, and mass balance by providing a direct ice-atmosphere interface where melt rates can be very high. As a result, ice cliffs act as windows of energy transfer from the atmosphere to the ice, and enhance melt and mass losses of otherwise insulated ice. However, their contribution to glacier mass balance has never been quantified at the glacier scale, and all inference has been obtained from upscaling results of point-scale models or observations at select individual cliffs. Here we use a 3D, physically-based backwasting model to estimate the volume losses associated with the melting and backwasting of supraglacial ice cliffs for the entire debris-covered glacier area of the Langtang catchment. We estimate mass losses for the 2014 melt season and compare them to recent values of glacier mass balance determined from geodetic and numerical modelling approached. Cliff outlines and topography are derived from high-resolution stereo SPOT6-imagery from April 2014. Meteorological data to force the model are provided by automatic weather stations on- and off-glacier within the valley. The model simulates ice cliff backwasting by considering the cliff-atmosphere energy-balance, reburial by debris and the effects of adjacent ponds. In the melt season of 2014, cliffs' distribution and patterns of mass losses vary considerably from glacier to glacier, and we relate rates of volume loss to both glaciers' and cliffs' characteristics. Only cliffs with a northerly aspect account for substantial losses. Uncertainty in our estimates is due to the quality of the stereo DEM, uncertainties in the cliff delineation and the fact that we use a conservative approach to cliff delineation and discard very small cliffs and those for which uncertainty in topography is high. Despite these uncertainties, our work presents the first estimate of the importance of supraglacial ice

  12. Chemical Records in Snowpits from High Altitude Glaciers in the Tibetan Plateau and Its Surroundings.

    PubMed

    Zhang, Yulan; Kang, Shichang; Zhang, Qianggong; Gao, Tanguang; Guo, Junming; Grigholm, Bjorn; Huang, Jie; Sillanpää, Mika; Li, Xiaofei; Du, Wentao; Li, Yang; Ge, Xinlei

    2016-01-01

    Glaciochemistry can provide important information about climatic change and environmental conditions, as well as for testing regional and global atmospheric trace transport models. In this study, δ18O and selected chemical constituents records in snowpits collected from eight glaciers in the Tibetan Plateau and adjacent areas have been investigated. Drawing on the integrated data, our study summarized the seasonal and spatial characteristics of snow chemistry, and their potential sources. Distinct seasonal patterns of δ18O values in snowpits indicated more negative in the south TP controlled by Indian monsoon, and less negative in the north TP and Tien Shan. Overall increasing concentrations of microparticles and crustal ions from south to north indicated a strength of dust deposition on glaciers from semi-arid and arid regions. Principal component analysis and air mass trajectories suggested that chemical constituents were mainly attributable to crustal sources as demonstrated by the high concentrations of ions occurring during the non-monsoon seasons. Nevertheless, other sources, such as anthropogenic pollution, played an important role on chemical variations of glaciers near the human activity centers. This study concluded that air mass transport from different sources played important roles on the spatial distributions and seasonality of glaciochemistry.

  13. Chemical Records in Snowpits from High Altitude Glaciers in the Tibetan Plateau and Its Surroundings

    PubMed Central

    Zhang, Yulan; Kang, Shichang; Zhang, Qianggong; Gao, Tanguang; Guo, Junming; Grigholm, Bjorn; Huang, Jie; Sillanpää, Mika; Li, Xiaofei; Du, Wentao; Li, Yang; Ge, Xinlei

    2016-01-01

    Glaciochemistry can provide important information about climatic change and environmental conditions, as well as for testing regional and global atmospheric trace transport models. In this study, δ18O and selected chemical constituents records in snowpits collected from eight glaciers in the Tibetan Plateau and adjacent areas have been investigated. Drawing on the integrated data, our study summarized the seasonal and spatial characteristics of snow chemistry, and their potential sources. Distinct seasonal patterns of δ18O values in snowpits indicated more negative in the south TP controlled by Indian monsoon, and less negative in the north TP and Tien Shan. Overall increasing concentrations of microparticles and crustal ions from south to north indicated a strength of dust deposition on glaciers from semi-arid and arid regions. Principal component analysis and air mass trajectories suggested that chemical constituents were mainly attributable to crustal sources as demonstrated by the high concentrations of ions occurring during the non-monsoon seasons. Nevertheless, other sources, such as anthropogenic pollution, played an important role on chemical variations of glaciers near the human activity centers. This study concluded that air mass transport from different sources played important roles on the spatial distributions and seasonality of glaciochemistry. PMID:27186638

  14. Future sea-level rise from tidewater and ice-shelf tributary glaciers of the Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Schannwell, Clemens; Barrand, Nicholas E.; Radić, Valentina

    2016-11-01

    Iceberg calving and increased ice discharge from ice-shelf tributary glaciers contribute significant amounts to global sea-level rise (SLR) from the Antarctic Peninsula (AP). Owing to ongoing ice dynamical changes (collapse of buttressing ice shelves), these contributions have accelerated in recent years. As the AP is one of the fastest warming regions on Earth, further ice dynamical adjustment (increased ice discharge) is expected over the next two centuries. In this paper, the first regional SLR projection of the AP from both iceberg calving and increased ice discharge from ice-shelf tributary glaciers in response to ice-shelf collapse is presented. An ice-sheet model forced by temperature output from 13 global climate models (GCMs), in response to the high greenhouse gas emission scenario (RCP8.5), projects AP contribution to SLR of 28 ± 16 to 32 ± 16 mm by 2300, partitioned approximately equally between contributions from tidewater glaciers and ice-shelf tributary glaciers. In the RCP4.5 scenario, sea-level rise projections to 2300 are dominated by tidewater glaciers (∼8-18 mm). In this cooler scenario, 2.4 ± 1 mm is added to global sea levels from ice-shelf tributary drainage basins as fewer ice-shelves are projected to collapse. Sea-level projections from ice-shelf tributary glaciers are dominated by drainage basins feeding George VI Ice Shelf, accounting for ∼70% of simulated SLR. Combined total ice dynamical SLR projections to 2300 from the AP vary between 11 ± 2 and 32 ± 16 mm sea-level equivalent (SLE), depending on the emission scenario used. These simulations suggest that omission of tidewater glaciers could lead to a substantial underestimation of the ice-sheet's contribution to regional SLR.

  15. The health of glaciers: Recent changes in glacier regime

    USGS Publications Warehouse

    Meier, M.F.; Dyurgerov, M.B.; McCabe, G.J.

    2003-01-01

    Glacier wastage has been pervasive during the last century; small glaciers and those in marginal environments are disappearing, large mid-latitude glaciers are shrinking slightly, and arctic glaciers are warming. Net mass balances during the last 40 years are predominately negative and both winter and summer balances (accumulation and ablation) and mass turnover are increasing, especially after 1988. Two principal components of winter balance time-series explain about 50% of the variability in the data. Glacier winter balances in north and central Europe correlate with the Arctic Oscillation, and glaciers in western North America correlate with the Southern Oscillation and Northern Hemisphere air temperature. The degree of synchronization for distant glaciers relates to changes in time of atmospheric circulation patterns as well as differing dynamic responses.

  16. Glaciers

    NASA Astrophysics Data System (ADS)

    Hambrey, Michael; Alean, Jürg

    2004-12-01

    Glaciers are among the most beautiful natural wonders on Earth, as well as the least known and understood, for most of us. Michael Hambrey describes how glaciers grow and decay, move and influence human civilization. Currently covering a tenth of the Earth's surface, glacier ice has shaped the landscape over millions of years by scouring away rocks and transporting and depositing debris far from its source. Glacier meltwater drives turbines and irrigates deserts, and yields mineral-rich soils as well as a wealth of valuable sand and gravel. However, glaciers also threaten human property and life. Our future is indirectly connected with the fate of glaciers and their influence on global climate and sea level. Including over 200 stunning photographs, the book takes the reader from the High-Arctic through North America, Europe, Asia, Africa, New Zealand and South America to the Antarctic. Michael Hambrey is Director of the Centre for Glaciology at the University of Wales, Aberystwyth. A past recipient of the Polar Medal, he was also given the Earth Science Editors' Outstanding Publication Award for the first edition of Glaciers (Cambridge, 1995). Hambrey is also the author of Glacial Environments (British Columbia, 1994). JÜrg Alean is Professor of Geography at the Kantonsschule ZÜrcher Unterland in BÜlach, Switzerland.

  17. Preliminary bathymetry of McCarty Fiord and Neoglacial changes of McCarty Glacier, Alaska

    USGS Publications Warehouse

    Post, Austin

    1980-01-01

    Preliminary bathymetry (at 1:20,000 scale) and other scientific studies of McCarty Fiord, Alaska, Conducted by the Research Vessel Growler in 1978, showed this 15 mile-long waterway to be a narrow, deeply scoured basin enclosed by a terminal-moraine shoal. This valley was formerly filled by McCarty Glacier, which began a drastic retreat shortly after 1909; the glacier reached shallow water at the head of the fiord around 1960. The relative rate of retreat in deep water and on land is disclosed by the slower melting of stagnent ice left in a side valley. Soundings and profiles show the main channel to extend to a depth as great as 957 feet and to have the typical ' U ' shape of a glacier-eroded valley; since the glacier 's retreat, sediments have formed a nearly level deposit in the deepest part of the fiord. Old forest debris dated by carbon-14 indicates that a neoglacial advance of the glacier began before 3,395 years B.P. (before present); by 1,500 B.P. the glacier filled most of the fiord, and before the glacier culminated its advance around 1860 , two glacier-dammed lakes were formed in side valleys. (USGS)

  18. Glaciers of Europe

    USGS Publications Warehouse

    Williams, Richard S.; Ferrigno, Jane G.

    1993-01-01

    ALPS: AUSTRIAN: An overview is provided on the occurrence of the glaciers in the Eastern Alps of Austria and on the climatic conditions in this area, Historical documents on the glaciers have been available since the Middle Ages. Special glaciological observations and topographic surveys of individual glaciers were initiated as early as 1846. Recent data in an inventory based on aerial photographs taken in 1969 show 925 glaciers in the Austrian Alps with a total area of 542 square kilometers. Present research topics include studies of mass and energy balance, relations of glaciers and climate, physical glaciology, a complete inventory of the glaciers, and testing of remote sensing methods. The location of the glacier areas is shown on Landsat multispectral scanner images; the improved capabilities of the Landsat thematic mapper are illustrated with an example from the Oztaler Alpen group. ALPS: SWISS: According to a glacier inventory published in 1976, which is based on aerial photography of 1973, there are 1,828 glacier units in the Swiss Alps that cover a total area of 1fl42 square kilometers. The Rhonegletscher, currently the ninth largest in the country, was one of the first to be studied in detail. Its surface has been surveyed repeatedly; velocity profiles were measured, and the fluctuations of its terminus were mapped and recorded from 1874 to 1914. Recent research on the glacier has included climatological, hydrological, and massbalance studies. Glaciological research has been conducted on various other glaciers in Switzerland concerning glacier hydrology, glacier hazards, fluctuations of glacier termini, ice mechanics, ice cores, and mass balance. Good maps are available showing the extent of glaciers from the latter decades of the 19th century. More recently, the entire country has been mapped at scales of 1:25,000, 1:50,000, 1:100,000, 1:200,000, and 1:500,000. The 1:25,000-scale series very accurately represents the glaciers as well as locates

  19. Dry calving processes at the ice cliff of an antarctic local glacier: the study case of Strandline Glacier (Northern Victoria Land, Antarctica)

    NASA Astrophysics Data System (ADS)

    Smiraglia, C.; Motta, M.; Vassena, G.; Diolaiuti, G.

    2003-04-01

    In Antartic coastal area, where the ice sheet and the large outlet glaciers do not reach the sea and where some rugged mountain chains are often present, many small glaciers can be found. They are the so called local or alpine type glaciers, which have their terminus ground-based such as the real alpine glaciers and rarely reach the main valley floors. They are practically isolated and independent from the supply flowing down from the plateau and their mass balance is mainly controlled by sublimation and aeolic erosion and accumulation. The glaciers closer to the coast are submitted to the melting as well, and when the terminus is cliff-shaped they are also affected by dry calving. The most known and studied Antarctic local glaciers are placed in the Dry Valleys region (Chinn, 1985), but this kind of glaciers is also diffused all along the Northern Victoria Land coastal region (Chinn and others, 1989). Since the first Italian Antarctic expedition (1985), many studies have been carried out on this type of glaciers, which can be usefull for detailed mass balance evaluations and for obtaining information about the effects of the present climatic dynamics on the Antarctic coastal environment (Baroni and Orombelli, 1987; Baroni and others, 1995; Meneghel, 1999; Vassena and others., 2001). The Strandline Glacier (74 41 S; 164 07 E), in particular is a small alpine glacier (0,79 kmq) on the coast of Terra Nova Bay, Northern Victoria Land; it is a cold glacier where accumulation and ablation basins are mainly controlled by wind processes. Its terminus forms in the central part a grounded ice cliff about 30 m high, about 130 m far from the sea. On that glacier mass balance, surface velocity and calving rate were measured. During the southern summer season 2000-2001 many topographycal profiles of the ice cliff were surveyed by using both classical topographical and glaciological methods (total station and stakes) and GPS technique. It was so possible to detect the short term

  20. Interactions of the Greenland Petermann Glacier with the ocean: An initial perspective (Invited)

    NASA Astrophysics Data System (ADS)

    Falkner, K. K.; Johnson, H. L.; Melling, H.; Muenchow, A.; Samelson, R. M.; Friends Of Petermann

    2010-12-01

    Petermann Glacier is major outlet glacier that drains 6% of the area of the Greenland Ice Sheet in western North Greenland. It is one of four major outlet glaciers on Greenland with a grounding line substantially below sea level (about 500m) and one of two such glaciers to retain a substantial floating tongue. The floating ice tongue of Petermann glacier is thought to lose at least 80% of its mass through ocean interaction. Based on three opportunistic ocean surveys in Petermann Fjord, we present an overview of circulation at the fjord mouth, hydrographic structure beneath the ice tongue, oceanic heat delivered to the under-ice cavity and the fate of the resulting melt water. We also present an historical perspective on the August 2010 major calving event. The 1100m-deep fjord is separated from neighboring Hall Basin by a sill that is inferred to lie between 350m and 450m deep. Hall Basin is a section of Nares Strait that connects the Arctic Ocean (at the Lincoln Sea proceeding southward through Robeson Channel, Hall Basin, Kennedy Channel, Kane Basin and Smith Sound) to Baffin Bay. Sills in the Lincoln Sea (290m) and in Kane Basin (220m) restrict communication with the Arctic Ocean and Baffin Bay. The net flux of seawater through Nares Strait is southward and relatively fresh, conditioned by sources and processes within the Arctic Ocean and locally. Within Petermann Fjord, glacial melt water appears on the northeast side at 200-600m. A cyclonic gyre occurs within the fjord mouth, with outflow on the northeast side. Oceanic heat fluxes into the fjord are sufficient to account for the observed rate of basal melting. Cold, low salinity water intrudes far under the ice and likely limits basal melting to the inland half of the tongue. The recent major calving event resulted in a loss of 300 km2 or about 20% of the total area of the floating tongue, most of which remained intact as an ice island that garnered much media attention. Available observations show calving to

  1. Testing wetland axioms at a watershed scale: Case studies of the aggregate hydrologic effects of non-adjacent wetlands

    EPA Science Inventory

    Wetlands not adjacent to streams (i.e. “non-adjacent wetlands”) are hypothesized to affect downgradient hydrology in a number of ways. Non-adjacent wetlands may, for example, attenuate peak flows, serve as focal points for groundwater recharge, and decrease streamflow...

  2. Microbial biodiversity in glacier-fed streams

    PubMed Central

    Wilhelm, Linda; Singer, Gabriel A; Fasching, Christina; Battin, Tom J; Besemer, Katharina

    2013-01-01

    While glaciers become increasingly recognised as a habitat for diverse and active microbial communities, effects of their climate change-induced retreat on the microbial ecology of glacier-fed streams remain elusive. Understanding the effect of climate change on microorganisms in these ecosystems is crucial given that microbial biofilms control numerous stream ecosystem processes with potential implications for downstream biodiversity and biogeochemistry. Here, using a space-for-time substitution approach across 26 Alpine glaciers, we show how microbial community composition and diversity, based on 454-pyrosequencing of the 16S rRNA gene, in biofilms of glacier-fed streams may change as glaciers recede. Variations in streamwater geochemistry correlated with biofilm community composition, even at the phylum level. The most dominant phyla detected in glacial habitats were Proteobacteria, Bacteroidetes, Actinobacteria and Cyanobacteria/chloroplasts. Microorganisms from ice had the lowest α diversity and contributed marginally to biofilm and streamwater community composition. Rather, streamwater apparently collected microorganisms from various glacial and non-glacial sources forming the upstream metacommunity, thereby achieving the highest α diversity. Biofilms in the glacier-fed streams had intermediate α diversity and species sorting by local environmental conditions likely shaped their community composition. α diversity of streamwater and biofilm communities decreased with elevation, possibly reflecting less diverse sources of microorganisms upstream in the catchment. In contrast, β diversity of biofilms decreased with increasing streamwater temperature, suggesting that glacier retreat may contribute to the homogenisation of microbial communities among glacier-fed streams. PMID:23486246

  3. A complex relationship between calving glaciers and climate

    USGS Publications Warehouse

    Post, A.; O'Neel, S.; Motyka, R.J.; Streveler, G.

    2011-01-01

    Many terrestrial glaciers are sensitive indicators of past and present climate change as atmospheric temperature and snowfall modulate glacier volume. However, climate interpretations based on glacier behavior require careful selection of representative glaciers, as was recently pointed out for surging and debris-covered glaciers, whose behavior often defies regional glacier response to climate [Yde and Paasche, 2010]. Tidewater calving glaciers (TWGs)mountain glaciers whose termini reach the sea and are generally grounded on the seaflooralso fall into the category of non-representative glaciers because the regional-scale asynchronous behavior of these glaciers clouds their complex relationship with climate. TWGs span the globe; they can be found both fringing ice sheets and in high-latitude regions of each hemisphere. TWGs are known to exhibit cyclic behavior, characterized by slow advance and rapid, unstable retreat, largely independent of short-term climate forcing. This so-called TWG cycle, first described by Post [1975], provides a solid foundation upon which modern investigations of TWG stability are built. Scientific understanding has developed rapidly as a result of the initial recognition of their asynchronous cyclicity, rendering greater insight into the hierarchy of processes controlling regional behavior. This has improved the descriptions of the strong dynamic feedbacks present during retreat, the role of the ocean in TWG dynamics, and the similarities and differences between TWG and ice sheet outlet glaciers that can often support floating tongues.

  4. A new interpretation of deformation rates in the Snake River Plain and adjacent basin and range regions based on GPS measurements

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    S.J. Payne; R. McCaffrey; R.W. King

    2012-04-01

    We evaluate horizontal Global Positioning System (GPS) velocities together with geologic, volcanic, and seismic data to interpret extension, shear, and contraction within the Snake River Plain and the Northern Basin and Range Province, U.S.A. We estimate horizontal surface velocities using GPS data collected at 385 sites from 1994 to 2009 and present an updated velocity field within the Stable North American Reference Frame (SNARF). Our results show an ENE-oriented extensional strain rate of 5.9 {+-} 0.7 x 10{sup -9} yr{sup -1} in the Centennial Tectonic belt and an E-oriented extensional strain rate of 6.2 {+-} 0.3 x 10{sup -9} yr{supmore » -1} in the Intermountain Seismic belt combined with the northern Great Basin. These extensional strain rates contrast with the regional north-south contraction of -2.6 {+-} 1.1 x 10{sup -9} yr{sup -1} calculated in the Snake River Plain and Owyhee-Oregon Plateau over a 125 x 650 km region. Tests that include dike-opening reveal that rapid extension by dike intrusion in volcanic rift zones does not occur in the Snake River Plain at present. This slow internal deformation in the Snake River Plain is in contrast to the rapidly-extending adjacent Basin and Range provinces and implies shear along boundaries of the Snake River Plain. We estimate right-lateral shear with slip rates of 0.5-1.5 mm/yr along the northwestern boundary adjacent to the Centennial Tectonic belt and left-lateral oblique extension with slip rates of <0.5 to 1.7 mm/yr along the southeastern boundary adjacent to the Intermountain Seismic belt. The fastest lateral shearing occurs near the Yellowstone Plateau where strike-slip focal mechanisms and faults with observed strike-slip components of motion are documented. The regional GPS velocity gradients are best fit by nearby poles of rotation for the Centennial Tectonic belt, Idaho batholith, Snake River Plain, Owyhee-Oregon Plateau, and central Oregon, indicating that clockwise rotation is driven by extension to

  5. Genetic status and conservation of Westslope Cutthroat Trout in Glacier National Park

    USGS Publications Warehouse

    Muhlfeld, Clint C.; D'Angelo, Vincent S.; Downs, Christopher C.; Powell, John D.; Amish, Stephen J.; Luikart, Gordon; Kovach, Ryan; Boyer, Matthew; Kalinowski, Steven T.

    2016-01-01

    Invasive hybridization is one of the greatest threats to the persistence of Westslope Cutthroat Trout Oncorhynchus clarkii lewisi. Large protected areas, where nonhybridized populations are interconnected and express historical life history and genetic diversity, provide some of the last ecological and evolutionary strongholds for conserving this species. Here, we describe the genetic status and distribution of Westslope Cutthroat Trout throughout Glacier National Park, Montana. Admixture between Westslope Cutthroat Trout and introduced Rainbow Trout O. mykiss and Yellowstone Cutthroat Trout O. clarkii bouvieri was estimated by genotyping 1,622 fish collected at 115 sites distributed throughout the Columbia, Missouri, and South Saskatchewan River drainages. Currently, Westslope Cutthroat Trout occupy an estimated 1,465 km of stream habitat and 45 lakes (9,218 ha) in Glacier National Park. There was no evidence of introgression in samples from 32 sites along 587 km of stream length (40% of the stream kilometers currently occupied) and 17 lakes (2,555 ha; 46% of the lake area currently occupied). However, nearly all (97%) of the streams and lakes that were occupied by nonhybridized populations occurred in the Columbia River basin. Based on genetic status (nonnative genetic admixture ≤ 10%), 36 Westslope Cutthroat Trout populations occupying 821 km of stream and 5,482 ha of lakes were identified as “conservation populations.” Most of the conservation populations (N = 27; 736 km of stream habitat) occurred in the Columbia River basin, whereas only a few geographically restricted populations were found in the South Saskatchewan River (N = 7; 55 km) and Missouri River (N = 2; 30 km) basins. Westslope Cutthroat Trout appear to be at imminent risk of genomic extinction in the South Saskatchewan and Missouri River basins, whereas populations in the Columbia River basin are widely distributed and conservation efforts are actively addressing threats from

  6. Glaciers change over the last century, Caucasus Mountains, Georgia, observed by the old topographical maps, Landsat and ASTER satellite imagery

    NASA Astrophysics Data System (ADS)

    Tielidze, L. G.

    2015-07-01

    The study of glaciers in the Caucasus began in the first quarter of the 18th century. The first data on glaciers can be found in the works of great Georgian scientist Vakhushti Bagrationi. After almost hundred years the foreign scientists began to describe the glaciers of Georgia. Information about the glaciers of Georgia can be found in the works of W. Abich (1865), D. Freshfield (1869), G. Radde (1873), N. Dinik (1884), I. Rashevskiy (1904), A. Reinhardt (1916, 1917) etc. The first statistical information about the glaciers of Georgia are found in the catalog of the Caucasus glaciers compiled by K. Podozerskiy in 1911 (Podozerkiy, 1911). Then, in 1960s the large-scale (1:25 000, 1:50 000) topographic maps were published, which were compiled in 1955-1960 on the basis of the space images. On the basis of the mentioned maps R. Gobejishvili gave quite detailed statistical information about the glaciers of Georgia (Gobejishvili, 1989). Then in 1975 the glaciological catalog of the former USSR was published (The Catalog of Glaciers of the USSR, Vol. 8-9, 1975), where the statistical information about the glaciers of Georgia was obtained on the basis of the space images of 1970-1975. Thus, complete statistical information on the glaciers of Georgia has not been published for about last 40 years. Data obtained by us by processing of the space images of Landsat and ASTER is the latest material, which is the best tool for identification of the change in the number and area of the glaciers of Georgia during the last one century. The article presents the percentage and quantitative changes in the number and area of the glaciers of Georgia in the years of 1911-1960-1975-2014, according to the individual river basins. The air temperature course of the Georgia's high mountain weather stations has been studied. The river basins have been revealed, where there are the highest indices of the reduction in area and number of the glaciers and the reasons have been explained.

  7. Combining a Distributed Melt Model and Meteorological Data of Shackleton Glacier, Canadian Rockies

    NASA Astrophysics Data System (ADS)

    Mueller, M.; Jiskoot, H.

    2010-12-01

    Runoff from the Canadian Rocky Mountains into the Upper Columbia and Kootenay basins is strongly dominated by winter snow accumulation and spring melt, and it has been suggested that future reductions in snowpack will create increased competition for water between spring and early fall (Hamlet & Lettenmaier, 1999). Although the glacierised area is substantial for affecting summer flows in these basins, there are no measurements or quantified estimates of glacier runoff contribution. In an effort to provide an estimate of glacier runoff for the region, we measured ablation over 5 years, set up weather stations and temperature sensors in Summers 2009 and 2010 and developed a melt model for Shackleton Glacier (42.5 km2), the largest outlet of the Clemenceau Icefield Group (271 km2), which is the major local ice mass feeding into the Upper Columbia basin. Two HOBO weather stations (WS) were installed on the glacier for two weeks in Summer 2010, one near the left lateral moraine on very dirty ice, and one mid-glacier on relatively clean ice. Instrumentation included pyranometers (solar radiation and albedo), and temperature, wind speed and direction, relative humidity and barometric pressure sensors. A weather station off ice provided additional temperature and precipitation data. Other data included daily ablation stake measurements, surface roughness measurements, temperature data from Tidbit loggers on and off ice, and daily manual weather observations. Yearly ablation stake measurements and summer weather observations have been made by our team since 2005. A BC River Forecast Centre automatic snow pillow station provides additional temperature and precipitation data. Using these meteorological and ablation data for parameterisation and optimisation, a distributed GIS melt model was constructed from a simple energy balance model. The model is driven by hourly direct and diffuse radiation and DEM hillshading, an albedo parameterisation based on four ice/snow zones

  8. 2. HORSESHOE CURVE IN GLACIER POINT ROAD NEAR GLACIER POINT. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. HORSESHOE CURVE IN GLACIER POINT ROAD NEAR GLACIER POINT. HALF DOME AT CENTER REAR. LOOKING NNE. GIS N-37 43 44.3 / W-119 34 14.1 - Glacier Point Road, Between Chinquapin Flat & Glacier Point, Yosemite Village, Mariposa County, CA

  9. Groundwater quality in the shallow aquifers of the Tulare, Kaweah, and Tule Groundwater Basins and adjacent highlands areas, Southern San Joaquin Valley, California

    USGS Publications Warehouse

    Fram, Miranda S.

    2017-01-18

    Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. The shallow aquifers of the Tulare, Kaweah, and Tule groundwater basins and adjacent highlands areas of the southern San Joaquin Valley constitute one of the study units being evaluated.

  10. Mass balance of Djankuat Glacier, Central Caucasus: observations, modeling and prediction

    NASA Astrophysics Data System (ADS)

    Rybak, Oleg; Mariia, Kaminskaia; Stanislav, Kutuzov; Ivan, Lavrentiev; Polina, Morozova; Victor, Popovnin; Elena, Rybak

    2017-04-01

    Djankuat is a typical valley glacier on the northern slope of the main Caucasus chain. Its present day area is approximately 2.5 square km with the characteristic ice thickness of several tens of meters. As well as other glaciers in the region, Djankuat has been shrinking during the last several decades, its cumulative mass balance in 1968-2016 was equal to -13.6 m w.e. In general, Caucasus' glaciers lost approximately one-third of their area and half of the volume. Prediction of further deradation of glaciers in changing environment is a challenging task because rivers fed by glacier melt water provide from 40 to 70% of the total river run-off in the adjacent piedmont territories. Growing demand in fresh water is rather critical for the local economy development and for growing population, motivating elaboration of an effitient instrument for evaluation and forecasting of the glaciation in the Greater Caucasus. Unfortunately, systematic observations are sparse limiting possibilities for proper model development for the most of the glaciers. Under these circumstances, we have to rely on the models developed for the few well-studied ones, like Djankuat, which is probably one of the most explored glaciers in the world. Accumulation and ablation rates have been observed here systematically and uninterruptedly since mid 60-ies using dense stake network. Together with the mass balance components, changes in flow velocity, ice thickness and geometry were regularly evaluated. During the last several ablation seasons, direct meteorological observations were carried out using an AMS. Long series of meteorological observations at the nearest weather station allow making assessment of the glacier response to climate change in the second half of the 20th century. Abundant observation data gave us the opportunity to elaborate, calibrate and validate an efficient mathematical model of surface mass balance of a typical glacier in the region. Since many glaciers in the Caucasus

  11. Snow cover trend and hydrological characteristics of the Astore River basin (Western Himalayas) and its comparison to the Hunza basin (Karakoram region).

    PubMed

    Tahir, Adnan Ahmad; Chevallier, Pierre; Arnaud, Yves; Ashraf, Muhammad; Bhatti, Muhammad Tousif

    2015-02-01

    A large proportion of Pakistan's irrigation water supply is taken from the Upper Indus River Basin (UIB) in the Himalaya-Karakoram-Hindukush range. More than half of the annual flow in the UIB is contributed by five of its snow and glacier-fed sub-basins including the Astore (Western Himalaya - south latitude of the UIB) and Hunza (Central Karakoram - north latitude of the UIB) River basins. Studying the snow cover, its spatio-temporal change and the hydrological response of these sub-basins is important so as to better manage water resources. This paper compares new data from the Astore River basin (mean catchment elevation, 4100 m above sea level; m asl afterwards), obtained using MODIS satellite snow cover images, with data from a previously-studied high-altitude basin, the Hunza (mean catchment elevation, 4650 m asl). The hydrological regime of this sub-catchment was analyzed using the hydrological and climate data available at different altitudes from the basin area. The results suggest that the UIB is a region undergoing a stable or slightly increasing trend of snow cover in the southern (Western Himalayas) and northern (Central Karakoram) parts. Discharge from the UIB is a combination of snow and glacier melt with rainfall-runoff at southern part, but snow and glacier melt are dominant at the northern part of the catchment. Similar snow cover trends (stable or slightly increasing) but different river flow trends (increasing in Astore and decreasing in Hunza) suggest a sub-catchment level study of the UIB to understand thoroughly its hydrological behavior for better flood forecasting and water resources management. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Role of lake regulation on glacier fed rivers in enhancing salmon productivity: The Cook Inlet watershed south central Alaska, USA

    USGS Publications Warehouse

    Hupp, C.R.

    2000-01-01

    Rivers fed by glaciers constitute a major part of the freshwater runoff into the Cook Inlet basin of south-central Alaska. This basin is very important to the economy of the State of Alaska because it is home to more than half of the population and it supports multi-million dollar commercial, subsistence and sport fisheries. Hence an understanding of how glacial runoff influences biological productivity is important for managing rivers that drain into Cook Inlet. This paper examines the ways in which the regulation of glacier-fed rivers by proglacial lakes affects salmon productivity, with particular reference to the Kenai River. Salmon escapement per unit channel length on the Kenai River is between two and ten times that found for rain-and-snowmelt dominated rivers and glacier-fed rivers lacking lake regulation. Lakes are shown to influence biological processes in glacier-fed rivers by attenuating peak flows, sustaining high flows throughout the summer, supplementing winter low flows, settling suspended sediment, and increasing river temperatures. Downstream from large lakes, glacier-fed rivers are less disturbed, channels are relatively stable and have well-developed salmonid habitats. The positive influences are indicated by the high diversity and abundances of benthic macroinvertebrates, which are important food resources for juvenile salmonids. High summer flows allow access for up-river salmon runs and lakes also provide both overwintering and rearing habitat. Copyright ?? 2000 John Wiley & Sons, Ltd.Rivers fed by glaciers constitute a major part of the freshwater runoff into the Cook Inlet basin of south-central Alaska. This basin is very important to the economy of the State of Alaska because it is home to more than half of the population and it supports multi-million dollar commercial, subsistence and sport fisheries. Hence an understanding of how glacial runoff influences biological productivity is important for managing rivers that drain into Cook Inlet

  13. Mercury speciation and distribution in a glacierized mountain environment and their relevance to environmental risks in the inland Tibetan Plateau.

    PubMed

    Sun, Xuejun; Zhang, Qianggong; Kang, Shichang; Guo, Junming; Li, Xiaofei; Yu, Zhengliang; Zhang, Guoshuai; Qu, Dongmei; Huang, Jie; Cong, Zhiyuan; Wu, Guangjian

    2018-08-01

    Glacierized mountain environments can preserve and release mercury (Hg) and play an important role in regional Hg biogeochemical cycling. However, the behavior of Hg in glacierized mountain environments and its environmental risks remain poorly constrained. In this research, glacier meltwater, runoff and wetland water were sampled in Zhadang-Qugaqie basin (ZQB), a typical glacierized mountain environment in the inland Tibetan Plateau, to investigate Hg distribution and its relevance to environmental risks. The total mercury (THg) concentrations ranged from 0.82 to 6.98ng·L -1 , and non-parametric pairwise multiple comparisons of the THg concentrations among the three different water samples showed that the THg concentrations were comparable. The total methylmercury (TMeHg) concentrations ranged from 0.041 to 0.115ng·L -1 , and non-parametric pairwise multiple comparisons of the TMeHg concentrations showed a significant difference. Both the THg and MeHg concentrations of water samples from the ZQB were comparable to those of other remote areas, indicating that Hg concentrations in the ZQB watershed are equivalent to the global background level. Particulate Hg was the predominant form of Hg in all runoff samples, and was significantly correlated with the total suspended particle (TSP) and not correlated with the dissolved organic carbon (DOC) concentration. The distribution of mercury in the wetland water differed from that of the other water samples. THg exhibited a significant correlation with DOC as well as TMeHg, whereas neither THg nor TMeHg was associated with TSP. Based on the above findings and the results from previous work, we propose a conceptual model illustrating the four Hg distribution zones in glacierized environments. We highlight that wetlands may enhance the potential hazards of Hg released from melting glaciers, making them a vital zone for investigating the environmental effects of Hg in glacierized environments and beyond. Copyright © 2018

  14. Attribution of glacier fluctuations to climate change

    NASA Astrophysics Data System (ADS)

    Oerlemans, J.

    2012-04-01

    , globally speaking, a 1 K temperature increase has the same effect as a ~25% decrease in precipitation, or a ~15% increase in global radiation. However, the relative importance of these drivers depends significantly on the climatic setting (notably continentality). In this contribution I will give a brief survey of glacier fluctuations over the past few centuries, and provide arguments that on the worldwide scale air temperature must have been the main driver of these fluctuations. A history of global mean temperature that explains the observed glacier fluctuations best will be discussed. On smaller spatial (regional) and temporal (decades) scales, changes in precipitation become important. Both with respect to the attribution problem (what caused the glacier fluctuations in the past?) and the projection issue (what will happen in the next 100 years?), it is important that many more glaciers are explicitly studied with numerical models. I will argue that for non-calving glaciers these models can be relatively simple.

  15. Recurrence of July Joklhlaup Flooding in the Mendenhall Glacier Watershed is Driven by Record Breaking Precipitation, Regional Warming, and the Collapse of a Tributary Glacier near Juneau, AK USA

    NASA Astrophysics Data System (ADS)

    Connor, C. L.; Hood, E. W.; Hekkers, M.; Kugler, N.

    2012-12-01

    During the summer of 2012, the U.S. Weather Service Station in Juneau, AK (located at 24 m asl and near the 1769 Little Ice Age terminal moraine of the Mendenhall Glacier), recorded the lowest daily average maximum May to July temperature of 12.2oC (54.9o F), [2.4oC (-4.4o F) below normal] over 69 years of record. This year's summer temperature anomalies contrast with an overall Juneau trend of warming 1.6oC, (2.88oF) since 1943. The rising temperature parallels glacier ice reduction by thinning at a rate of >2m/yr and ice terminus retreat of 3.86 km between 1909 and 2011. Mendenhall Lake which began forming after 1930 has increased from 3.9 to 4.2 km2 in area and 0.05-0.09 km3 in volume between 2000 and 2011 as the glacier retreated. Since 2000, maximum lake depth has increased from 70 to 90m at the lakefront terminus. Northeast and 3.6 km above the glacier terminus, the Suicide Basin Ice Fall no longer flows into Mendenhall glacier, which has created a large ice-marginal basin that can hold a substantial volume of water. Once rare, mid-summer flooding has recently been caused by abrupt subglacial releases of rain water stored in this tributary cirque basin. Large water volumes are lifting and flowing under the surviving main trunk of the Mendenhall Glacier. These glacial outburst floods have raised Mendenhall Lake levels and increased discharge into the outlet Mendenhall River. On July 19-22, 2011 an estimated subglacial discharge of 37,000,000 m3 (1,306,642,650 ft3) raised proglacial Mendenhall Lake level by 1.67m (5.5 ft) and increased discharge on the Mendenhall River from 79 to 453 m3/s (2,800-16,000 f3/s). Temperature sensor strings on buoys in the lake have captured lake bottom (-49m) temperature drops of ~ 1oC as cold waves of subglacially released water move at depth from the glacier base into the river. Lake temperature data from summer 2012 sensors will be presented at this meeting. During summer 2012, a repeat joklhlaup event occurred July 3-6, rising

  16. HORSESHOE CURVE IN GLACIER POINT ROAD NEAR GLACIER POINT. HALF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    HORSESHOE CURVE IN GLACIER POINT ROAD NEAR GLACIER POINT. HALF DOME AT CENTER REAR. SAME VIEW AT CA-157-2. LOOKING NNE. GIS: N-37' 43 44.3 / W-119 34 14.1 - Glacier Point Road, Between Chinquapin Flat & Glacier Point, Yosemite Village, Mariposa County, CA

  17. Identifying surging glaciers in the Central Karakoram for improved climate change impact assessment

    NASA Astrophysics Data System (ADS)

    Paul, Frank; Bolch, Tobias; Mölg, Nico; Rastner, Philipp

    2015-04-01

    Several recent studies have investigated glacier changes in the Karakoram mountain range, a region where glaciers behave differently (mass gain and advancing tongues) compared to most other regions in the world. Attribution of this behaviour to climate change is challenging, as many glaciers in the Karakoram are of surge type and have actively surged in the recent past. The measured changes in length, area, volume or velocity in this region are thus depending on the time-period analysed and include non-climatic components. Hence, a proper analysis of climate change impacts on glaciers in this region requires a separation of the surging from the non-surging glaciers. This is challenging as the former often lack the typical surface characteristics such as looped moraines (e.g. when they are steep and small) and/or they merge (during a surge) with a larger non-surging glacier and create looped moraines on its surface. By analysing time series of satellite images that are available since 1961, the heterogeneous behaviour of glaciers in the Karakoram can be revealed. In this study, we have analysed changes in glacier terminus positions in the Karakoram over different time periods from 1961 to 2014 for several hundred glaciers using Corona KH-4 and KH-4B, Hexagon KH-9, Terra ASTER, and Landsat MSS, TM, ETM+ and OLI satellite data. For the last 15 years, high-speed animations of image time-series reveal details of glacier flow and surge dynamics that are otherwise difficult to detect. For example, several of the larger glaciers with surging tributaries (e.g. Panmah, Sarpo Laggo, Skamri, K2 glacier) are stationary and downwasting despite the mass contributions from the surging glaciers. The analysis of the entire time series reveals a complex pattern of changes through time with retreating, advancing, surging and stationary glaciers that are partly regionally clustered. While most of the non-surging glaciers show only small changes in terminus position (±100 m or less

  18. Neoglacial fluctuations of terrestrial, tidewater, and calving lacustrine glaciers, Blackstone-Spencer Ice Complex, Kenai Mountains, Alaska

    NASA Astrophysics Data System (ADS)

    Crossen, Kristine June

    1997-12-01

    The glaciers surrounding the Blackstone-Spencer Ice Complex display a variety of termini types: Tebenkov, Spencer, Bartlett, Skookum, Trail, Burns, Shakespeare, Marquette, Lawrence, and Ripon glaciers end in terrestrial margins; Blackstone and Beloit glaciers have tidewater termini; and Portage Glacier has a calving lacustrine margin. In addition, steep temperature and precipitation gradients exist across the ice complex from the maritime environment of Prince William Sound to the colder, drier interior. The Neoglacial history of Tebenkov Glacier, as based on overrun trees near the terminus, shows advances ca. 250- 430 AD (calibrated date), ca. 1215-1275 AD (calibrated date), and ca. 1320-1430 AD (tree ring evidence), all intervals of glacier advance around the Gulf of Alaska. However, two tidewater glaciers in Blackstone Bay retreated from their outermost moraines by 1350 AD, apparently asynchronously with respect to the regional climate signal. The most extensive Kenai Mountain glacier expansions during Neoglaciation occurred in the late Little Ice Age. The outermost moraines are adjacent to mature forest stands and bog peats that yield dates as old as 5,600 BP. Prince William Sound glaciers advanced during two Little Ice Age cold periods, 1380-1680 and 1830-1900 AD. The terrestrial glaciers around the Blackstone-Spencer Ice Complex all built moraines during the 19th century and began retreating between 1875 and 1900 AD. Portage and Burns glaciers began retreating between 1790 and 1810 AD, but their margins remained close to the outermost moraines during the 19th century. Regional glacier fluctuations are broadly synchronous in the Gulf of Alaska region. With the exception of the two tidewater glaciers in Blackstone Bay, all glaciers in the Kenai Mountains, no matter their sizes, altitudes, orientations, or types of margins, retreated at the end of the Little Ice Age. The climate signal, especially temperature, appears to be the strongest control on glacier

  19. Malaspina Glacier, Alaska

    NASA Image and Video Library

    2003-05-01

    Malaspina Glacier in southeastern Alaska is considered the classic example of a piedmont glacier. Piedmont glaciers occur where valley glaciers exit a mountain range onto broad lowlands, are no longer laterally confined, and spread to become wide lobes.

  20. How do glacier inventory data aid global glacier assessments and projections?

    NASA Astrophysics Data System (ADS)

    Hock, R.

    2017-12-01

    Large-scale glacier modeling relies heavily on datasets that are collected by many individuals across the globe, but managed and maintained in a coordinated fashion by international data centers. The Global Terrestrial Network for Glaciers (GTN-G) provides the framework for coordinating and making available a suite of data sets such as the Randolph Glacier Inventory (RGI), the Glacier Thickness Dataset or the World Glacier Inventory (WGI). These datasets have greatly increased our ability to assess global-scale glacier mass changes. These data have also been vital for projecting the glacier mass changes of all mountain glaciers in the world outside the Greenland and Antarctic ice sheet, a total >200,000 glaciers covering an area of more than 700,000 km2. Using forcing from 8 to 15 GCMs and 4 different emission scenarios, global-scale glacier evolution models project multi-model mean net mass losses of all glaciers between 7 cm and 24 cm sea-level equivalent by the end of the 21st century. Projected mass losses vary greatly depending on the choice of the forcing climate and emission scenario. Insufficiently constrained model parameters likely are an important reason for large differences found among these studies even when forced by the same emission scenario, especially on regional scales.

  1. Listening to Glaciers: Passive hydroacoustics near marine-terminating glaciers

    USGS Publications Warehouse

    Pettit, E.C.; Nystuen, J.A.; O'Neel, Shad

    2012-01-01

    The catastrophic breakup of the Larsen B Ice Shelf in the Weddell Sea in 2002 paints a vivid portrait of the effects of glacier-climate interactions. This event, along with other unexpected episodes of rapid mass loss from marine-terminating glaciers (i.e., tidewater glaciers, outlet glaciers, ice streams, ice shelves) sparked intensified study of the boundaries where marine-terminating glaciers interact with the ocean. These dynamic and dangerous boundaries require creative methods of observation and measurement. Toward this effort, we take advantage of the exceptional sound-propagating properties of seawater to record and interpret sounds generated at these glacial ice-ocean boundaries from distances safe for instrument deployment and operation.

  2. The Petermann Glacier Experiment, NW Greenland

    NASA Astrophysics Data System (ADS)

    Mix, A. C.; Jakobsson, M.; Andrews, J. T.; Jennings, A. E.; Mayer, L. A.; Marcott, S. A.; Muenchow, A.; Stoner, J. S.; Andresen, C. S.; Nicholls, K. W.; Anderson, S. T.; Brook, E.; Ceperley, E. G.; Cheseby, M.; Clark, J.; Dalerum, F.; Dyke, L. M.; Einarsson, D.; Eriksson, B.; Frojd, C.; Glueder, A.; Hedman, U.; Heirman, K.; Heuzé, C.; Hogan, K.; Holden, R.; Holm, C.; Jerram, K.; Krutzfeldt, J.; Nicolas, L.; Par, L.; Lomac-MacNair, K.; Madlener, S.; McKay, J. L.; Meijer, T.; Meiton, A.; Brian, M.; Mohammed, R.; Molin, M.; Moser, C.; Normark, E.; Padman, J.; Pecnerova, P.; Reilly, B.; Reusche, M.; Ross, A.; Stranne, C.; Trinhammer, P.; Walczak, M. H.; Walczak, P.; Washam, P.; Karasti, M.; Anker, P.

    2016-12-01

    The Petermann Glacier Experiment is a comprehensive study on land, ocean, and ice in Northwest Greenland, staged from Swedish Icebreaker Oden in 2015 as a collaboration between the US, Sweden, UK, and Denmark. This talk introduces the strategic goals of the experiment and connects the various scientific results. Petermann Glacier drains a significant marine-based sector of the northern Greenland Ice Sheet and terminates in a floating ice tongue, one of the largest remaining systems of its kind in the northern hemisphere. Records of the modern state of Petermann Glacier and its past variations are of interest to understand the sensitivity of marine terminating outlet glaciers to change, and to constrain the rates and extent of changes that have actually occurred. With this case study we are learning the rules of large scale dynamics that cannot be understood from modern observations alone. Although past behavior is not an simple analog for the future, and no single system captures all possible behaviors, insights from these case studies can be applied through models to better project how similar systems may change in the future. The Petermann Expedition developed the first comprehensive bathymetric maps of the region, drilled through the floating ice tongue to obtain sub-shelf sediment cores near the grounding line and to monitor sub-ice conditions, recovered a broad array of sediment cores documenting changing oceanic conditions in Petermann Fjord, Hall Basin, and Nares Strait, measured watercolumn properties to trace subsurface watermasses that bring heat from the Arctic Ocean into deep Petermann Fjord to melt the base of the floating ice tongue, developed a detailed record of relative sealevel change on land to constrain past ice loads, and recovered pristine boulders for cosmogenic exposure dating of areal ice retreat on land. Together, these studies are shedding new light on the dynamics of past glaciation in Northwest Greenland, and contributing to fundamental

  3. Pathways of Petermann Glacier meltwater, Greenland

    NASA Astrophysics Data System (ADS)

    Heuzé, Céline; Wåhlin, Anna; Johnson, Helen; Münchow, Andreas

    2016-04-01

    Radar and satellite observations suggest that the floating ice shelf of Petermann Glacier loses up to 80% of its mass through basal melting, caused by the intrusion of warm Atlantic Water into the fjord and under the ice shelf. The fate of Petermann's glacial meltwater is still largely unknown. It is investigated here, using hydrographic observations collected during a research cruise on board I/B Oden in August 2015. Two methods are used to detect the meltwater from Petermann: a mathematical one that provides the concentration of ice shelf meltwater, and a geometrical one to distinguish the meltwater from Petermann and the meltwater from other ice shelves. The meltwater from Petermann mostly circulates on the north side of the fjord. At the sill, 0.5 mSv of meltwater leave the fjord, mostly on the northeastern side between 100 and 350 m depth, but also in the central channel, albeit with a lesser concentration. Meltwater from Petermann is found in all the casts in Hall Basin, notably north of the sill by Greenland coast. The geometrical method reveals that the casts closest to the Canadian side mostly contain meltwater from other, unidentified glaciers. As Atlantic Water warms up, it is key to monitor Greenland melting glaciers and track their meltwater to properly assess their impact on the ocean circulation and sea level rise.

  4. Pathways of Petermann Glacier's Meltwaters, Greenland

    NASA Astrophysics Data System (ADS)

    Heuzé, C.; Wahlin, A.; Johnson, H. L.; Muenchow, A.

    2016-02-01

    Radar and satellite observations suggest that the floating ice shelf of Petermann glacier, north Greenland, loses up to 80% of its mass through basal melting, caused by the intrusion of warm Atlantic water into the fjord and under the ice shelf. Although Greenland meltwaters are key to sea level rise projections and can potentially disrupt the whole ocean circulation, the fate of Petermann's glacial meltwater is still largely unknown. It is investigated here, using hydrographic observations collected during a research cruise onboard I/B Oden in August 2015. Two layers are found: one at 200 m (i.e. terminus depth) mostly on the eastern side of the fjord where a calving event occurred this summer, and one around 500 m depth (i.e. the grounding line) on the western side. At the sill, approximately 3 mSv of freshwater leave the fjord around 150 m on the eastern side. On the western side, a more complex circulation occurs as waters intrude in. Outside of the fjord in Hall Basin, only one layer is found, around 300 m, but its oxygen content and T-S properties suggests it is a mixture between Petermann's meltwater, meltwater from the neighbouring glaciers, surface run-off and sea ice. As Atlantic water warms up, it is key to monitor Greenland melting glaciers to properly assess sea level rise.

  5. [Mercury Transport from Glacier to Runoff in Typical Inland Glacial Area in the Tibetan Plateau].

    PubMed

    Sun, Xue-jun; Wang, Kang; Guo, Jun-ming; Kang, Shi-chang; Zhang, Guo-shuai; Huang, Jie; Cong, Zhi-yuan; Zhang, Qiang-gong

    2016-02-15

    To investigate the transport of mercury from glacier to runoff in typical inland glacial area in the Tibetan Plateau, we selected Zhadang glacier and Qugaqie river Basin located in the Nyainqentanglha Range region and collected samples from snow pit, glacier melt-water and Qugaqie river water during 15th August to 9'h September 2011. Mercury speciation and concentrations were determined and their distribution and controlling factors in different environmental compartments were analyzed. The results showed that the average THg concentrations were (3.79 +/- 5.12) ng x L(-1), (1.06 +/- 0.77) ng x L(-1) and (1.02 +/- 0.24) ng x L(-1) for glacier snow, glacier melt-water and Qugaqie river water, respectively, all of which were at the global background levels. Particulate-bound mercury accounted for large proportion of mercury in all environmental matrices, while mercury in glacial melt-water was controlled by total suspended particle, and mercury in Qugaqie river water co-varied with runoff. With the increase of temperature, glacier melted and released water as well as mercury into glacier-fed river. Total mercury concentrations in glacier melt water, upstream and downstream peaked at 14:00, 16:00 and after 20:00, respectively, reflecting the process of mercury release from glacier and its subsequent transport in the glacier fed river. The transport of riverine mercury was controlled by multiple factors. Under the context of climate change, glacier ablation and the increasing runoff will play increasingly important roles in mercury release and transport.

  6. Ice dynamics of Himalayan glaciers (Himachal Pradesh, India) using TerraSAR-X/TanDEM-X data.

    NASA Astrophysics Data System (ADS)

    Vijay, Saurabh; Braun, Matthias

    2015-04-01

    Mountain glaciers are the natural indicators of climate change. Himalaya is a part of widely spread mountain range consisting of second largest ice mass after polar region. The glaciers in Himalaya are located in Himachal Pradesh and other territories of India. The precipitation in the region is influenced by both Indian summer monsoon and mid-latitude winter westerlies. The glacier discharge influences the river basins and provides fresh water for various infrastructural necessities of urbanization in the state. The study aims to estimate the ice thickness and volume change during the decade (2011-2000) and annually during 2011-2014. For this, TanDEM-X DEMs are subtracted from the SRTM C/X band DEM of 2000. In addition, ice flow dynamics are quantified by the constellation of TerraSAR-X/TanDEM-X data using SAR offset tracking method. The primary investigations reveal that the terminus velocity of Bada Shigri (G077683E32169N), the biggest glacier of the state, Chhota Shigri( G077513E32227N), a bench-mark glacier, and other glacier (G077547E32162N) in 2011 found out to be < 2cm/day. The upper stream velocities of the glaciers are increased linearly and influenced by glacier tributaries.

  7. Malaspina Glacier, Alaska, Anaglyph with Landsat Overlay

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This anaglyph view of Malaspina Glacier in southeastern Alaska was created from a Landsat satellite image and an elevation model generated by the Shuttle Radar Topography Mission (SRTM). Malaspina Glacier is considered the classic example of a piedmont glacier. Piedmont glaciers occur where valley glaciers exit a mountain range onto broad lowlands, are no longer laterally confined, and spread to become wide lobes. Malaspina Glacier is actually a compound glacier, formed by the merger of several valley glaciers, the most prominent of which seen here are Agassiz Glacier (left) and Seward Glacier (right). In total, Malaspina Glacier is up to 65 kilometers (40 miles) wide and extends up to 45 kilometers (28 miles) from the mountain front nearly to the sea.

    Glaciers erode rocks, carry them down slope, and deposit them at the edge of the melting ice, typically in elongated piles called moraines. The moraine patterns at Malaspina Glacier are quite spectacular in that they have huge contortions that result from the glacier crinkling as it gets pushed from behind by the faster-moving valley glaciers.

    Numerous other features of the glaciers and the adjacent terrain are clearly seen when viewing this image at full resolution. The series of tonal arcs on Agassiz Glacier's extension onto the piedmont are called 'ogives.' These arcs are believed to be seasonal features created by deformation of the glacier as it passes over bedrock irregularities at differing speeds through the year. Assuming one light-and-dark ogive pair per year, the rate of motion of the glacial ice can be estimated (in this case, about 200 meters per year where the ogives are most prominent). Just to the west, moraine deposits abut the eroded bedrock terrain, forming a natural dam that has created a lake. Near the northwest corner of the scene, a recent landslide has deposited rock debris atop a small glacier. Sinkholes are common in many areas of the moraine deposits. The sinkholes form when

  8. Hydrochemical simulation of a mountain basin under hydrological variability

    NASA Astrophysics Data System (ADS)

    Montserrat, S.; Trewhela, T. A.; Navarro, L.; Navarrete, A.; Lagos Zuniga, M. A.; Garcia, A.; Caraballo, M.; Niño, Y.; McPhee, J. P.

    2016-12-01

    Water quality and the comprehension of hydrochemical phenomena in natural basins should be of complete relevance under hydrological uncertainties. The importance of identifying the main variables that are controlling a natural system and finding a way to predict their behavior under variable scenarios is mandatory to preserve these natural basins. This work presents an interdisciplinary model for the Yerba Loca watershed, a natural reserve basin in the Chilean central Andes. Based on different data sets, provided by public and private campaigns, a natural hydrochemical regime was identified. Yerba Loca is a natural reserve, characterized by the presence of several glaciers and wide sediment deposits crossed by a small low-slope creek in the upper part of the basin that leads to a high-slope narrow channel with less sediment depositions. Most relevant is the geological context around the glaciers, considering that most of them cover hydrothermal zones rich in both sulfides and sulfates, a situation commonly found in the Andes due to volcanic activity. Low pH (around 3), calcium-sulfate water with high concentrations of Iron, Copper and Zinc are found in the upper part of the basin in summer. These values can be attributed to the glaciers melting down and draining of the mentioned country rocks, which provide most of the creek flow in the upper basin. The latter clearly contrasts with the creek outlet, located 18 km downstream, showing near to neutral pH values and lower concentrations of the elements already mentioned. The scope of the present research is to account for the sources of the different hydrological inlets (e.g., rainfall, snow and/or glacier melting) that, depending on their location, may interact with a variety of reactive minerals and generate acid rock drainage (ARD). The inlet water is modeled along the creek using the softwares HEC-RAS and PHREEQC coupled, in order to characterize the water quality and to detect preferred sedimentation sections

  9. Tropical Glaciers

    NASA Astrophysics Data System (ADS)

    Fountain, Andrew

    The term "tropical glacier" calls to mind balmy nights and palm trees on one hand and cold, blue ice on the other. Certainly author Gabriel Garcia Marqez exploited this contrast in One Hundred Years of Solitude. We know that tropical fish live in warm, Sun-kissed waters and tropical plants provide lush, dense foliage populated by colorful tropical birds. So how do tropical glaciers fit into this scene? Like glaciers everywhere, tropical glaciers form where mass accumulation—usually winter snow—exceeds mass loss, which is generally summer melt. Thus, tropical glaciers exist at high elevations where precipitation can occur as snowfall exceeds melt and sublimation losses, such as the Rwenzori Mountains in east Africa and the Maoke Range of Irian Jaya.

  10. Evidence for persistent organic pollutants released from melting glacier in the central Tibetan Plateau, China.

    PubMed

    Li, Jun; Yuan, Guo-Li; Wu, Ming-Zhe; Sun, Yong; Han, Peng; Wang, Gen-Hou

    2017-01-01

    Glacier alluvial deposits record persistent organic pollutants (POPs) not only derived from the atmospheric deposition but also from the release of glacial melting. The evidence for melting glacier in the Tibetan Plateau (TP) as a secondary source of pollutants is introduced through investigating the concentration of organochlorine pesticides (OCPs) in four deposited profiles collected at the edge of the Changwengluozha glacier. Two concentration peaks were observed for dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs) in the past century. The first peak was observed in the 1970s, corresponding with the heavy usage of HCHs and DDTs in the surrounding countries and regions. The second one was in 2000 when the production and usage of DDTs and HCHs were strictly limited, which possibly indicated a significant release from melting glacier. This result was further supported by the enantiomeric fraction values for α-HCH and o,p'-DDT. On the other hand, the dramatic increase of polycyclic aromatic hydrocarbons (PAHs) from atmospheric deposition, which was associated with the socioeconomic development in Tibet, shaded the release of PAHs from melting glacier. This study reveals not only the air deposition history of legacy POPs but also a substantial release of OCPs from glacier to the adjacent environment. Our research supports the hypothesis that the melting glacier in the TP represents a secondary source of OCPs, which is consistent with the findings in the Alps glaciers. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Chemical characterisation of meltwater draining from Gangotri Glacier, Garhwal Himalaya, India

    NASA Astrophysics Data System (ADS)

    Singh, Virendra Bahadur; Ramanathan, Al; Pottakkal, Jose George; Sharma, Parmanand; Linda, Anurag; Azam, Mohd Farooq; Chatterjee, C.

    2012-06-01

    A detailed analytical study of major cations (Ca2 + , Mg2 + , Na + , K + ) and anions (SO4^{2-}, HCO3-, Cl - , NO3-) of meltwater draining from Gangotri Glacier was carried out to understand major ion chemistry and to get an insight into geochemical weathering processes controlling hydrochemistry of the glacier. In the meltwater, the abundance order of cations and anions varied as follows: Ca2 + > Mg2 + > K + > Na + and SO4^{2-} > HCO3- > Cl - > NO3-, respectively. Calcium and magnesium are dominant cations while sulphate and bicarbonate are dominant anions. Weathering of rocks is the dominant mechanism controlling the hydrochemistry of drainage basin. The relative high contribution of (Ca+Mg) to the total cations (TZ + ), high (Ca+Mg)/(Na+K) ratio (2.63) and low (Na+K)/TZ + ratio (0.29) indicate the dominance of carbonate weathering as a major source for dissolved ions in the glacier meltwater. Sulphide oxidation and carbonation are the main proton supplying geochemical reactions controlling the rock weathering in the study area. Statistical analysis was done to identify various factors controlling the dissolved ionic strength of Gangotri Glacier meltwater.

  12. Complex patterns of glacier advances during the Lateglacial in the Chagan-Uzun Valley, Russian Altai

    NASA Astrophysics Data System (ADS)

    Gribenski, Natacha; Lukas, Sven; Jansson, Krister N.; Stroeven, Arjen P.; Preusser, Frank; Harbor, Jonathan M.; Blomdin, Robin; Ivanov, Mikhail N.; Heyman, Jakob; Petrakov, Dmitry; Rudoy, Alexei; Clifton, Tom; Lifton, Nathaniel A.; Caffee, Marc W.

    2016-04-01

    Over the last decades, numerous paleoglacial reconstructions have been carried out in Central Asian mountain ranges because glaciers in this region are sensitive to climate change, and thus their associated glacial deposits can be used as proxies for paleoclimate inference. However, non-climatic factors can complicate the relationship between glacier fluctuation and climate change. Careful investigations of the geomorphological and sedimentological context are therefore required to understand the mechanisms behind glacier retreat and expansion. In this study we present the first detailed paleoglacial reconstruction of the Chagan Uzun valley, located in the Russian Altai. This reconstruction is based on detailed geomorphological mapping, sedimentological logging, in situ cosmogenic 10Be and 26Al surface exposure dating of glacially transported boulders, and Optically Stimulated Luminescence (OSL) dating. The Chagan Uzun valley includes extensive lobate moraine belts (>100 km2) deposited in the intramontane Chuja basin, reflecting a series of pronounced former glacial advances. Observation of "hillside-scale" folding and extensive faulting of pre-existing soft sediments within the outer moraine belts, together with the geomorphology, indicate that these moraine belts were formed during glacier-surge like events. In contrast, the inner (up-valley) glacial landforms of the Chagan Uzun valley indicate that they were deposited by retreat of temperate valley glaciers and do not include features indicative of surging. Cosmogenic ages associated with the outermost, innermost and intermediary stages, all indicate deposition times clustered around 19.5 ka, although the 10Be ages of the outermost margin are likely slightly underestimated due to brief episode of glacial lake water coverage. Such close deposition timings are consistent with periods of fast or surge advances, followed by active glacier retreat. OSL dating yields significantly older ages of thick lacustrine

  13. Mass counts: ERP correlates of non-adjacent dependency learning under different exposure conditions.

    PubMed

    Citron, Francesca M M; Oberecker, Regine; Friederici, Angela D; Mueller, Jutta L

    2011-01-10

    Miniature language learning can serve to model real language learning as high proficiency can be reached after very little exposure. In a previous study by Mueller et al. [18] German participants acquired non-adjacent syntactic dependencies by mere exposure to correct Italian sentences, but their ERP pattern differed from the one shown by native speakers. The present study follows up on that experiment using a similar design and material and is focused on two important issues: the influence of acoustic cues in the material and the impact of the learning procedure. With respect to the latter we compared alternating learning and test phases to a continuous learning and test phase. In addition, a splicing procedure eliminated prosodic cues in order to ensure that non-adjacent dependencies were learned instead of adjacent ones. Results for the continuous phase design showed a native-like biphasic ERP pattern, an N400 followed by a left-focused positivity. In the alternating design behavioural accuracy was lower and only an N400 was found. The results suggest an advantage of continuous learning phases for adult learners, possibly due to the absence of ungrammatical items present in the test phases in the alternating learning procedure. Furthermore, the replication of the earlier study with prosodically controlled material adds evidence to the general finding that syntactic non-adjacent dependencies can be learned from mere exposure to correct examples. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  14. Recent Ice Loss from the Fleming and Other Glaciers, Wordie Bay, West Antarctic Peninsula

    NASA Technical Reports Server (NTRS)

    Rignot, E.; Casassa, G.; Gogineni, S.; Kanagaratnam, P.; Krabill, W.; Pritchard, H.; Rivera, A.; Thomas, R.; Turner, J.; Vaughan, D.

    2005-01-01

    Satellite radar interferometry data from 1995 to 2004, and airborne ice thickness data from 2002, reveal that the glaciers flowing into former Wordie Ice Shelf, West Antarctic Peninsula, discharge 6.8 +/- 0.3 km(exp 3)/yr of ice, which is 84 +/- 30 percent larger than a snow accumulation of 3.7 +/- 0.8 km(exp 3)/yr over a 6,300 km(exp 2) drainage basin. Airborne and ICESat laser altimetry elevation data reveal glacier thinning at rates up to 2 m/yr. Fifty km from its ice front, Fleming Glacier flows 50 percent faster than it did in 1974 prior to the main collapse of Wordie Ice Shelf. We conclude that the glaciers accelerated following ice shelf removal, and have been thinning and losing mass to the ocean over the last decade. This and other observations suggest that the mass loss from the northern part of the Peninsula is not negligible at present.

  15. Sea ice breakup and marine melt of a retreating tidewater outlet glacier in northeast Greenland (81°N).

    PubMed

    Bendtsen, Jørgen; Mortensen, John; Lennert, Kunuk; K Ehn, Jens; Boone, Wieter; Galindo, Virginie; Hu, Yu-Bin; Dmitrenko, Igor A; Kirillov, Sergei A; Kjeldsen, Kristian K; Kristoffersen, Yngve; G Barber, David; Rysgaard, Søren

    2017-07-10

    Rising temperatures in the Arctic cause accelerated mass loss from the Greenland Ice Sheet and reduced sea ice cover. Tidewater outlet glaciers represent direct connections between glaciers and the ocean where melt rates at the ice-ocean interface are influenced by ocean temperature and circulation. However, few measurements exist near outlet glaciers from the northern coast towards the Arctic Ocean that has remained nearly permanently ice covered. Here we present hydrographic measurements along the terminus of a major retreating tidewater outlet glacier from Flade Isblink Ice Cap. We show that the region is characterized by a relatively large change of the seasonal freshwater content, corresponding to ~2 m of freshwater, and that solar heating during the short open water period results in surface layer temperatures above 1 °C. Observations of temperature and salinity supported that the outlet glacier is a floating ice shelf with near-glacial subsurface temperatures at the freezing point. Melting from the surface layer significantly influenced the ice foot morphology of the glacier terminus. Hence, melting of the tidewater outlet glacier was found to be critically dependent on the retreat of sea ice adjacent to the terminus and the duration of open water.

  16. 36 CFR 13.1132 - What types of commercial fishing are authorized in Glacier Bay?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... fishing are authorized in Glacier Bay? 13.1132 Section 13.1132 Parks, Forests, and Public Property...-Glacier Bay National Park and Preserve Commercial Fishing § 13.1132 What types of commercial fishing are authorized in Glacier Bay? Three types of commercial fishing are authorized in Glacier Bay non-wilderness...

  17. 36 CFR 13.1132 - What types of commercial fishing are authorized in Glacier Bay?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... fishing are authorized in Glacier Bay? 13.1132 Section 13.1132 Parks, Forests, and Public Property...-Glacier Bay National Park and Preserve Commercial Fishing § 13.1132 What types of commercial fishing are authorized in Glacier Bay? Three types of commercial fishing are authorized in Glacier Bay non-wilderness...

  18. 36 CFR 13.1132 - What types of commercial fishing are authorized in Glacier Bay?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... fishing are authorized in Glacier Bay? 13.1132 Section 13.1132 Parks, Forests, and Public Property...-Glacier Bay National Park and Preserve Commercial Fishing § 13.1132 What types of commercial fishing are authorized in Glacier Bay? Three types of commercial fishing are authorized in Glacier Bay non-wilderness...

  19. Glaciers of South America

    USGS Publications Warehouse

    Williams, Richard S.; Ferrigno, Jane G.

    1998-01-01

    Landsat images, together with maps and aerial photographs, have been used to produce glacier inventories, define glacier locations, and study glacier dynamics in the countries of South America, along with the Andes Mountains. In Venezuela, Colombia, Ecuador, and Bolivia, the small glaciers have been undergoing extensive glacier recession since the late 1800's. Glacier-related hazards (outburst floods, mud flows, and debris avalanches) occur in Colombia, in Ecuador, and associated with the more extensive (2,600 km2) glaciers of Peru. The largest area of glacier ice is found in Argentina and Chile, including the northern Patagonian ice field (about 4,200 km2) and the southern Patagonian ice field (about 13,000 km2), the largest glacier in the Southern Hemisphere outside Antarctica.

  20. Integrated firn elevation change model for glaciers and ice caps

    NASA Astrophysics Data System (ADS)

    Saß, Björn; Sauter, Tobias; Braun, Matthias

    2016-04-01

    We present the development of a firn compaction model in order to improve the volume to mass conversion of geodetic glacier mass balance measurements. The model is applied on the Arctic ice cap Vestfonna. Vestfonna is located on the island Nordaustlandet in the north east of Svalbard. Vestfonna covers about 2400 km² and has a dome like shape with well-defined outlet glaciers. Elevation and volume changes measured by e.g. satellite techniques are becoming more and more popular. They are carried out over observation periods of variable length and often covering different meteorological and snow hydrological regimes. The elevation change measurements compose of various components including dynamic adjustments, firn compaction and mass loss by downwasting. Currently, geodetic glacier mass balances are frequently converted from elevation change measurements using a constant conversion factor of 850 kg m-³ or the density of ice (917 kg m-³) for entire glacier basins. However, the natural conditions are rarely that static. Other studies used constant densities for the ablation (900 kg m-³) and accumulation (600 kg m-³) areas, whereby density variations with varying meteorological and climate conditions are not considered. Hence, each approach bears additional uncertainties from the volume to mass conversion that are strongly affected by the type and timing of the repeat measurements. We link and adapt existing models of surface energy balance, accumulation and snow and firn processes in order to improve the volume to mass conversion by considering the firn compaction component. Energy exchange at the surface is computed by a surface energy balance approach and driven by meteorological variables like incoming short-wave radiation, air temperature, relative humidity, air pressure, wind speed, all-phase precipitation, and cloud cover fraction. Snow and firn processes are addressed by a coupled subsurface model, implemented with a non-equidistant layer discretisation. On

  1. Observed glacier and volatile distribution on Pluto from atmosphere-topography processes.

    PubMed

    Bertrand, Tanguy; Forget, François

    2016-12-01

    Pluto has a variety of surface frosts and landforms as well as a complex atmosphere. There is ongoing geological activity related to the massive Sputnik Planitia glacier, mostly made of nitrogen (N 2 ) ice mixed with solid carbon monoxide and methane, covering the 4-kilometre-deep, 1,000-kilometre-wide basin of Sputnik Planitia near the anti-Charon point. The glacier has been suggested to arise from a source region connected to the deep interior, or from a sink collecting the volatiles released planetwide. Thin deposits of N 2 frost, however, were also detected at mid-northern latitudes and methane ice was observed to cover most of Pluto except for the darker, frost-free equatorial regions. Here we report numerical simulations of the evolution of N 2 , methane and carbon monoxide on Pluto over thousands of years. The model predicts N 2 ice accumulation in the deepest low-latitude basin and the threefold increase in atmospheric pressure that has been observed to occur since 1988. This points to atmospheric-topographic processes as the origin of Sputnik Planitia's N 2 glacier. The same simulations also reproduce the observed quantities of volatiles in the atmosphere and show frosts of methane, and sometimes N 2 , that seasonally cover the mid- and high latitudes, explaining the bright northern polar cap reported in the 1990s and the observed ice distribution in 2015. The model also predicts that most of these seasonal frosts should disappear in the next decade.

  2. Observed glacier and volatile distribution on Pluto from atmosphere-topography processes

    NASA Astrophysics Data System (ADS)

    Bertrand, Tanguy; Forget, François

    2016-12-01

    Pluto has a variety of surface frosts and landforms as well as a complex atmosphere. There is ongoing geological activity related to the massive Sputnik Planitia glacier, mostly made of nitrogen (N2) ice mixed with solid carbon monoxide and methane, covering the 4-kilometre-deep, 1,000-kilometre-wide basin of Sputnik Planitia near the anti-Charon point. The glacier has been suggested to arise from a source region connected to the deep interior, or from a sink collecting the volatiles released planetwide. Thin deposits of N2 frost, however, were also detected at mid-northern latitudes and methane ice was observed to cover most of Pluto except for the darker, frost-free equatorial regions. Here we report numerical simulations of the evolution of N2, methane and carbon monoxide on Pluto over thousands of years. The model predicts N2 ice accumulation in the deepest low-latitude basin and the threefold increase in atmospheric pressure that has been observed to occur since 1988. This points to atmospheric-topographic processes as the origin of Sputnik Planitia’s N2 glacier. The same simulations also reproduce the observed quantities of volatiles in the atmosphere and show frosts of methane, and sometimes N2, that seasonally cover the mid- and high latitudes, explaining the bright northern polar cap reported in the 1990s and the observed ice distribution in 2015. The model also predicts that most of these seasonal frosts should disappear in the next decade.

  3. Energy and mass balance observations on La Mare Glacier (Ortles-Cevedale, European Alps)

    NASA Astrophysics Data System (ADS)

    Carturan, L.; Cazorzi, F.; Dalla Fontana, G.

    2009-04-01

    An experimental site was setup in 2005 on the ablation area of La Mare Glacier, at 2990 m a.s.l., to study the energy and mass balance exchanges between the glacier surface and the atmosphere and to investigate the climatic sensitivity of this particular glacier. An Automatic Weather Station was operated, in the framework of a monitoring network which has been implemented in the Upper Val de La Mare experimental watershed (Trentino, Italy). This basin was selected for a study of climate change effects on cryosphere and hydrology at high-altitude catchments. The 36.2 km2 wide basin has an average altitude of 2906 m a.s.l. and at present the 25% of its surface is glacierized; the annual runoff regime is dominated by snow and ice melt. Direct mass balance measurements have been performed since 1967 on Careser glacier (2.83 km2) and since 2003 on La Mare glacier (3.97 km2). The AWS is mounted on a tripod which stands freely on the glacier surface and is solar-powered. The variables measured are: air temperature and relative humidity, wind speed and direction, shortwave and longwave incoming and outgoing radiation, precipitation and surface height. All the data are sampled at five-minute intervals as average values, with the exception of surface height which is sampled at hourly intervals, as instantaneous values. The collected data were used to calculate the point energy and mass balance and to compare the results with similar investigations carried out on glaciers and available in literature. In particular, our attention has been focussed on some processes which regulate the response to climate changes. The relative importance of the energy balance components was examined and a clear predominance of shortwave radiation inputs was found to exist during melt conditions. Given the relevance of the shortwave net balance, the ice albedo temporal variability (values ranging from 0.1 to 0.5) has been investigated and correlated with meteorological variables. Furthermore, a

  4. Non-target adjacent stimuli classification improves performance of classical ERP-based brain computer interface

    NASA Astrophysics Data System (ADS)

    Ceballos, G. A.; Hernández, L. F.

    2015-04-01

    Objective. The classical ERP-based speller, or P300 Speller, is one of the most commonly used paradigms in the field of Brain Computer Interfaces (BCI). Several alterations to the visual stimuli presentation system have been developed to avoid unfavorable effects elicited by adjacent stimuli. However, there has been little, if any, regard to useful information contained in responses to adjacent stimuli about spatial location of target symbols. This paper aims to demonstrate that combining the classification of non-target adjacent stimuli with standard classification (target versus non-target) significantly improves classical ERP-based speller efficiency. Approach. Four SWLDA classifiers were trained and combined with the standard classifier: the lower row, upper row, right column and left column classifiers. This new feature extraction procedure and the classification method were carried out on three open databases: the UAM P300 database (Universidad Autonoma Metropolitana, Mexico), BCI competition II (dataset IIb) and BCI competition III (dataset II). Main results. The inclusion of the classification of non-target adjacent stimuli improves target classification in the classical row/column paradigm. A gain in mean single trial classification of 9.6% and an overall improvement of 25% in simulated spelling speed was achieved. Significance. We have provided further evidence that the ERPs produced by adjacent stimuli present discriminable features, which could provide additional information about the spatial location of intended symbols. This work promotes the searching of information on the peripheral stimulation responses to improve the performance of emerging visual ERP-based spellers.

  5. Pathways of warm water to the Northeast Greenland outlet glaciers

    NASA Astrophysics Data System (ADS)

    Schaffer, Janin; Timmermann, Ralph; Kanzow, Torsten; Arndt, Jan Erik; Mayer, Christoph; Schauer, Ursula

    2015-04-01

    The ocean plays an important role in modulating the mass balance of the Greenland Ice Sheet by delivering heat to the marine-terminating outlet glaciers surrounding the Greenland coast. The warming and accumulation of Atlantic Water in the subpolar North Atlantic has been suggested to be a potential driver of the glaciers' retreat over the last decades. The shelf regions thus play a critical role for the transport of Atlantic Water towards the glaciers, but also for the transfer of freshwater towards the deep ocean. A key region for the mass balance of the Greenland Ice Sheet is the Northeast Greenland Ice Stream. This large ice stream drains the second-largest basin of the Greenland Ice Sheet and feeds three outlet glaciers. The largest one is Nioghalvfjerdsfjorden (79°N-Glacier) featuring an 80 km long floating ice tongue. Both the ocean circulation on the continental shelf off Northeast Greenland and the circulation in the cavity below the ice tongue are weakly constrained so far. In order to study the relevant processes of glacier-ocean interaction we combine observations and model work. Here we focus on historic and recent hydrographic observations and on the complex bathymetry in the Northeast Greenland shelf region, which is thought to steer the flux of warm Atlantic water onto the continental shelf and into the sub-ice cavity beneath the 79°N-Glacier. We present a new global topography data set, RTopo-2, which includes the most recent surveys on the Northeast Greenland continental shelf and provides a detailed bathymetry for all around Greenland. In addition, RTopo-2 contains ice and bedrock surface topographies for Greenland and Antarctica. Based on the updated ocean bathymetry and a variety of hydrographic observations we show the water mass distribution on the continental shelf off Northeast Greenland. These maps enable us to discuss possible supply pathways of warm modified Atlantic waters on the continental shelf and thus potential ways of heat

  6. Glacier meltwater flow paths and storage in a geomorphologically complex glacial foreland: the case of the Tapado glacier, dry Andes of Chile (30°S)

    NASA Astrophysics Data System (ADS)

    Pourrier, J.; Jourde, H.; Kinnard, C.; Gascoin, S.; Monnier, S.

    2013-12-01

    In the Dry Andes, high altitude glacierized catchments are important contributor to streamflow and aquifer recharge. In this study we focused on the Tapado catchment, (30°S, 9 km2, elevation range: 4000m - 5550m) located in the upper Elqui river basin in northern Chile. This catchment encompasses the Tapado glacial complex, composed of an assemblage of the Tapado glacier and the glacial foreland (debris-covered glacier, rock glacier and moraines). Here we present the results of intensive hydrometeorological observations conducted over the 2011 glacier melt season (February to April). Weather, discharge and water electrical conductivity were monitored near the glacier snout and at the outlet of the glacial foreland. GPR observations realized on the glacial foreland are used to verify or complete interpretations of underground transfer modalities. The results show that the water production from the Tapado glacier is highly correlated with weather conditions, in particular incoming shortwave radiation and air temperature. Resulting daily and seasonal streamflow variability is buffered by the glacial foreland, where underground transfers occur through complex flow paths. However, the development of a thermokarst drainage network in a part of the glacial foreland, allows fast and concentrated water transfers, which reduces this buffering effect. The glacial foreland is shown to act as a reservoir, storing water during period of strong ice melt and providing water to downstream areas during periods of low melt. The internal structure of the glacial foreland revealed by GPR observations corroborates these analyses. The south-western part is composed by massive ice, covered by rock debris. The north-eastern part is composed by mixed ice and rock debris, presenting spatially variable ice content. Finally, the computation of the catchment water balance shows that the Tapado catchment presents a particularly high specific discharge in summer under a dry hydro

  7. An Active Englacial Hydrological System in a Cold Glacier: Blood Falls, Taylor Glacier, Antarctica

    NASA Astrophysics Data System (ADS)

    Carr, C. G.; Pettit, E. C.; Carmichael, J.; Badgeley, J.; Tulaczyk, S. M.; Lyons, W. B.; Mikucki, J.

    2016-12-01

    Blood Falls is a supraglacial hydrological feature formed by episodic release of iron-rich subglacial brine derived from an extensive aquifer beneath the cold, polar, Taylor Glacier. While fluid transport in non-temperate ice typically occurs through meltwater delivery from the glacier surface to the bed (hydrofracturing, supraglacial lake drainage), Blood Falls represents the opposite situation: brine moves from a subglacial source to the glacier surface. Here, we present the first complete conceptual model for brine transport and release, as well as the first direct evidence of a wintertime brine release at Blood Falls obtained through year-round time-lapse photography. Related analyses show that brine pools subglacially underneath the northern terminus of Taylor Glacier, rather than flowing directly into proglacial Lake Bonney because ice-cored moraines and channelized surface topography provide hydraulic barriers. This pooled brine is pressurized by hydraulic head from the upglacier brine source region. Based on seismic data, we propose that episodic supraglacial release is initiated by high strain rates coupled with pressurized subglacial brine that drive intermittent subglacial and englacial fracturing. Ultimately, brine-filled basal crevasses propagate upward to link with surface crevasses, allowing brine to flow from the bed to the surface. The observation of wintertime brine release indicates that surface-generated meltwater is not necessary to trigger crack propagation or to maintain the conduit as previously suggested. The liquid brine persists beneath and within the cold ice (-17°C) despite ambient ice/brine temperature differences of as high as 10°C through both locally depressed brine freezing temperatures through cryoconcentration of salts and increased ice temperatures through release of latent heat during partial freezing of brine. The existence of an englacial hydrological system initiated by basal crevassing extends to polar glaciers a process

  8. The deep structure of the Sichuan basin and adjacent orogenic zones revealed by the aggregated deep seismic profiling datum

    NASA Astrophysics Data System (ADS)

    Xiong, X.; Gao, R.; Li, Q.; Wang, H.

    2012-12-01

    The sedimentary basin and the orogenic belt are the basic two tectonic units of the continental lithosphere, and form the basin-mountain coupling system, The research of which is the key element to the oil and gas exploration, the global tectonic theory and models and the development of the geological theory. The Sichuan basin and adjacent orogenic belts is one of the most ideal sites to research the issues above, in particular by the recent deep seismic profiling datum. From the 1980s to now, there are 11 deep seismic sounding profiles and 6 deep seismic reflection profiles and massive seismic broadband observation stations deployed around and crossed the Sichuan basin, which provide us a big opportunity to research the deep structure and other forward issues in this region. Supported by the National Natural Science Foundation of China (Grant No. 41104056) and the Fundamental Research Funds of the Institute of Geological Sciences, CAGS (No. J1119), we sampled the Moho depth and low-velocity zone depth and the Pn velocity of these datum, then formed the contour map of the Moho depth and Pn velocity by the interpolation of the sampled datum. The result shows the Moho depth beneath Sichuan basin ranges from 40 to 44 km, the sharp Moho offset appears in the western margin of the Sichuan basin, and there is a subtle Moho depression in the central southern part of the Sichuan basin; the P wave velocity can be 6.0 km/s at ca. 10 km deep, and increases gradually deeper, the average P wave velocity in this region is ca. 6.3 km/s; the Pn velocity is ca. 8.0-8.02 km/s in Sichuan basin, and 7.70-7.76 km/s in Chuan-Dian region; the low velocity zone appears in the western margin of the Sichuan basin, which maybe cause the cause of the earthquake.

  9. IceBridge Provides Novel Evidence for Thick Units of Basal Freeze-on Ice Along Petermann Glacier, Greenland

    NASA Astrophysics Data System (ADS)

    Bell, R. E.; Tinto, K. J.; Wolovick, M.; Block, A. E.; Frearson, N.; Das, I.; Abdi, A.; Creyts, T. T.; Cochran, J. R.; Csatho, B. M.; Babonis, G. S.

    2011-12-01

    The Petermann Glacier, one of the major outlet glaciers in Greenland, drains six percent of the Greenland ice from a basin largely below sea level. Petermann Glacier and its large ice shelf may be susceptible to increased change as the waters along the Greenland margin warm. The 2010 and 2011 Operation IceBridge mission, acquired a comprehensive aerogeophysical data set over the Petermann Glacier that provides insights into the ice sheet structure. This analysis employs most of the data streams acquired by the Icebridge platform including ice-penetrating radar, laser altimetry, gravity and magnetics. An orthogonal 10 km grid extends from 60 km upstream of the grounding line to 240 km inland. The ice velocities in the region range from <50m/yr to >200m/yr. On the interior lines the internal layers are pulled down over 2-3 km wide regions. Up to 400m of ice from the base of the ice sheet appears to be absent in these regions. We interpret these pulled down regions as basal melt. These melt regions are mainly located along the upstream side of a 80 km wide east-west trending topographic ridge that separates the interior ice from the Petermann Fjord. The IceBridge magnetic data indicates that this broad flat ridge is the boundary between the Franklinian Basins and the Ellsmerian Foldbelt to the north. Downstream of these pull-down layers we have identified 4 distinct packages of ice that thicken downstream and are characterized by a strong upper reflector. These packages develop at the base of the ice sheet and reach thicknesses of 500-700m over distances of 10-20 km. These basal packages can be traced for 30-100 km following the direction of flow, and may be present close to the grounding line. These basal reflectors deflect the overlying internal layers upward indicating the addition of ice to the base of the ice sheet. The IceBridge gravity data indicates that these features are probably not off-nadir topography since these would show up as around 30mGal anomalies

  10. Role of lake regulation on glacier-fed rivers in enhancing salmon productivity: the Cook Inlet watershed, south-central Alaska, USA

    NASA Astrophysics Data System (ADS)

    Dorava, Joseph M.; Milner, Alexander M.

    2000-10-01

    Rivers fed by glaciers constitute a major part of the freshwater runoff into the Cook Inlet basin of south-central Alaska. This basin is very important to the economy of the State of Alaska because it is home to more than half of the population and it supports multi-million dollar commercial, subsistence and sport fisheries. Hence an understanding of how glacial runoff influences biological productivity is important for managing rivers that drain into Cook Inlet. This paper examines the ways in which the regulation of glacier-fed rivers by proglacial lakes affects salmon productivity, with particular reference to the Kenai River. Salmon escapement per unit channel length on the Kenai River is between two and ten times that found for rain-and-snowmelt dominated rivers and glacier-fed rivers lacking lake regulation.Lakes are shown to influence biological processes in glacier-fed rivers by attenuating peak flows, sustaining high flows throughout the summer, supplementing winter low flows, settling suspended sediment, and increasing river temperatures. Downstream from large lakes, glacier-fed rivers are less disturbed, channels are relatively stable and have well-developed salmonid habitats. The positive influences are indicated by the high diversity and abundances of benthic macroinvertebrates, which are important food resources for juvenile salmonids. High summer flows allow access for up-river salmon runs and lakes also provide both overwintering and rearing habitat.

  11. Towards the Complete Characterization of Marine-Terminating Glacier Outlet Systems

    NASA Astrophysics Data System (ADS)

    Mayer, L. A.; Jakobsson, M.; Mix, A. C.; Jerram, K.; Hogan, K.; Heffron, E.; Muenchow, A.

    2016-12-01

    The Petermann Glacier Experiment was aimed at understanding past variations in Petermann Glacier and their relationship to changes in climatic and oceanographic conditions. A critical component of the experiment was a comprehensive program conducted on the icebreaker Oden to map submarine glacial landforms, offering insight into past ice dynamics and establishing the overall geomorphological context of the region. Concurrent water-column mapping provided remarkable insight into modern glacial, oceanographic, and biological processes suggesting that a carefully designed experiment could provide a near-complete characterization of marine-terminating glacier outlet systems. Water-column mapping revealed seeps emanating from several seafloor regions. These features appeared along common depth zones and may represent fresh water emanating from a submerged aquifer; initial pore water analyses of cores also imply a fresh water flux into the fjord system. Water-column data also show a spatially consistent but variable distribution of a strong mid-water scattering layer, a biological response possibly tracing the inflow of Atlantic water into the fjord and enhanced by input from local outlet glaciers. The continuous nature of these acoustic records over 30 days offers a complete 4-D picture of the distribution of the scattering layer (and perhaps internal circulation patterns and water-mass interactions) with a spatial and temporal distribution far beyond that achievable by traditional oceanographic stations. Additional, higher-resolution water-column imaging around local outlet glaciers presents a clear picture of subglacial sediment-laden meltwater plumes. Thus in addition to the paleoceanographic information they provided, the acoustic systems deployed captured a 4D-view of many of the modern geological, oceanographic and ecological processes within and adjacent to the Petermann Glacier marine system. With the addition of seafloor and water-column sampling, long

  12. Modeling the dynamic response of a crater glacier to lava-dome emplacement: Mount St Helens, Washington, USA

    USGS Publications Warehouse

    Price, Stephen F.; Walder, Joseph S.

    2007-01-01

    The debris-rich glacier that grew in the crater of Mount St Helens after the volcano's cataclysmic 1980 eruption was split in two by a new lava dome in 2004. For nearly six months, the eastern part of the glacier was squeezed against the crater wall as the lava dome expanded. Glacier thickness nearly doubled locally and surface speed increased substantially. As squeezing slowed and then stopped, surface speed fell and ice was redistributed downglacier. This sequence of events, which amounts to a field-scale experiment on the deformation of debris-rich ice at high strain rates, was interpreted using a two-dimensional flowband model. The best match between modeled and observed glacier surface motion, both vertical and horizontal, requires ice that is about 5 times stiffer and 1.2 times denser than normal, temperate ice. Results also indicate that lateral squeezing, and by inference lava-dome growth adjacent to the glacier, likely slowed over a period of about 30 days rather than stopping abruptly. This finding is supported by geodetic data documenting dome growth.

  13. Pleistocene glaciers, lakes, and floods in north-central Washington State

    USGS Publications Warehouse

    Waitt, Richard B.; Haugerud, Ralph A.; Kelsey, Harvey M.

    2017-01-01

    The Methow, Chelan, Wenatchee, and other terrane blocks accreted in late Mesozoic to Eocene times. Methow valley is excavated in an exotic terrane of folded Mesozoic sedimentary and volcanic rocks faulted between crystalline blocks. Repeated floods of Columbia River Basalt about 16 Ma drowned a backarc basin to the southeast. Cirques, aretes, and U-shaped hanging troughs brand the Methow, Skagit, and Chelan headwaters. The Late Wisconsin Cordilleran icesheet beveled the alpine topography and deposited drift. Cordilleran ice flowed into the heads of Methow tributaries and overflowed from Skagit tributaries to greatly augment Chelan trough's glacier. Joined Okanogan and Methow ice flowed down Columbia valley and up lower Chelan trough. This tongue met the icesheet tongue flowing southeast down Chelan valley. Successively lower ice-marginal channels and kame terraces show that the icesheet withered away largely by downwasting. Immense late Wisconsin floods from glacial Lake Missoula occasionally swept the Chelan-Vantage reach of Columbia valley by different routes. The earliest debacles, nearly 19,000 cal yr BP (by radiocarbon methods), raged 335 m deep down the Columbia and built high Pangborn bar at Wenatchee. As Cordilleran ice blocked the northwest of Columbia valley, several giant floods descended Moses Coulee and backflooded up the Columbia. As advancing ice then blocked Moses Coulee, Grand Coulee to Quincy basin became the westmost floodway. From Quincy basin many Missoula floods backflowed 50 km upvalley past Wenatchee 18,000 to 15,500 years ago. Receding ice dammed glacial Lake Columbia centuries more--till it burst about 15,000 years ago. After Glacier Peak ashfall about 13,600 years ago, smaller great flood(s) swept down the Columbia from glacial Lake Kootenay in British Columbia. A cache of huge fluted Clovis points had been laid atop Pangborn bar (East Wenatchee) after the Glacier Peak ashfall. Clovis people came two and a half millennia after the last

  14. Glacier melt buffers river runoff in the Pamir Mountains

    NASA Astrophysics Data System (ADS)

    Pohl, Eric; Gloaguen, Richard; Andermann, Christoff; Knoche, Malte

    2017-03-01

    Newly developed approaches based on satellite altimetry and gravity measurements provide promising results on glacier dynamics in the Pamir-Himalaya but cannot resolve short-term natural variability at regional and finer scale. We contribute to the ongoing debate by upscaling a hydrological model that we calibrated for the central Pamir. The model resolves the spatiotemporal variability in runoff over the entire catchment domain with high efficiency. We provide relevant information about individual components of the hydrological cycle and quantify short-term hydrological variability. For validation, we compare the modeled total water storages (TWS) with GRACE (Gravity Recovery and Climate Experiment) data with a very good agreement where GRACE uncertainties are low. The approach exemplifies the potential of GRACE for validating even regional scale hydrological applications in remote and hard to access mountain regions. We use modeled time series of individual hydrological components to characterize the effect of climate variability on the hydrological cycle. We demonstrate that glaciers play a twofold role by providing roughly 35% of the annual runoff of the Panj River basin and by effectively buffering runoff both during very wet and very dry years. The modeled glacier mass balance (GMB) of -0.52 m w.e. yr-1 (2002-2013) for the entire catchment suggests significant reduction of most Pamiri glaciers by the end of this century. The loss of glaciers and their buffer functionality in wet and dry years could not only result in reduced water availability and increase the regional instability, but also increase flood and drought hazards.Plain Language Summary<span class="hlt">Glaciers</span> store large amounts of water in the form of ice. They grow and shrink dominantly in response to climatic conditions. In Central Asia, where rivers originate in the high mountains, <span class="hlt">glaciers</span> are an important source for sustainable water availability. Thus</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=dependency&pg=5&id=EJ1011717','ERIC'); return false;" href="https://eric.ed.gov/?q=dependency&pg=5&id=EJ1011717"><span><span class="hlt">Non-Adjacent</span> Dependency Learning in Infants at Familial Risk of Dyslexia</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Kerkhoff, Annemarie; de Bree, Elise; de Klerk, Maartje; Wijnen, Frank</p> <p>2013-01-01</p> <p>This study tests the hypothesis that developmental dyslexia is (partly) caused by a deficit in implicit sequential learning, by investigating whether infants at familial risk of dyslexia can track <span class="hlt">non-adjacent</span> dependencies in an artificial language. An implicit learning deficit would hinder detection of such dependencies, which mark grammatical…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015TCry....9..197D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015TCry....9..197D"><span><span class="hlt">Glacier</span>-surge mechanisms promoted by a hydro-thermodynamic feedback to summer melt</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dunse, T.; Schellenberger, T.; Hagen, J. O.; Kääb, A.; Schuler, T. V.; Reijmer, C. H.</p> <p>2015-02-01</p> <p>Mass loss from <span class="hlt">glaciers</span> and ice sheets currently accounts for two-thirds of the observed global sea-level rise and has accelerated since the 1990s, coincident with strong atmospheric warming in the polar regions. Here we present continuous GPS measurements and satellite synthetic-aperture-radar-based velocity maps from <span class="hlt">Basin</span>-3, the largest drainage <span class="hlt">basin</span> of the Austfonna ice cap, Svalbard. Our observations demonstrate strong links between surface-melt and multiannual ice-flow acceleration. We identify a hydro-thermodynamic feedback that successively mobilizes stagnant ice regions, initially frozen to their bed, thereby facilitating fast basal motion over an expanding area. By autumn 2012, successive destabilization of the marine terminus escalated in a surge of <span class="hlt">Basin</span>-3. The resulting iceberg discharge of 4.2±1.6 Gt a-1 over the period April 2012 to May 2013 triples the calving loss from the entire ice cap. With the seawater displacement by the terminus advance accounted for, the related sea-level rise contribution amounts to 7.2±2.6 Gt a-1. This rate matches the annual ice-mass loss from the entire Svalbard archipelago over the period 2003-2008, highlighting the importance of dynamic mass loss for <span class="hlt">glacier</span> mass balance and sea-level rise. The active role of surface melt, i.e. external forcing, contrasts with previous views of <span class="hlt">glacier</span> surges as purely internal dynamic instabilities. Given sustained climatic warming and rising significance of surface melt, we propose a potential impact of the hydro-thermodynamic feedback on the future stability of ice-sheet regions, namely at the presence of a cold-based marginal ice plug that restricts fast drainage of inland ice. The possibility of large-scale dynamic instabilities such as the partial disintegration of ice sheets is acknowledged but not quantified in global projections of sea-level rise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C33B0814C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C33B0814C"><span>Estimating stream discharge from a Himalayan <span class="hlt">Glacier</span> using coupled satellite sensor data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Child, S. F.; Stearns, L. A.; van der Veen, C. J.; Haritashya, U. K.; Tarpanelli, A.</p> <p>2015-12-01</p> <p>The 4th IPCC report highlighted our limited understanding of Himalayan <span class="hlt">glacier</span> behavior and contribution to the region's hydrology. Seasonal snow and <span class="hlt">glacier</span> melt in the Himalayas are important sources of water, but estimates greatly differ about the actual contribution of melted <span class="hlt">glacier</span> ice to stream discharge. A more comprehensive understanding of the contribution of <span class="hlt">glaciers</span> to stream discharge is needed because streams being fed by <span class="hlt">glaciers</span> affect the livelihoods of a large part of the world's population. Most of the streams in the Himalayas are unmonitored because in situ measurements are logistically difficult and costly. This necessitates the use of remote sensing platforms to obtain estimates of river discharge for validating hydrological models. In this study, we estimate stream discharge using cost-effective methods via repeat satellite imagery from Landsat-8 and SENTINEL-1A sensors. The methodology is based on previous studies, which show that ratio values from optical satellite bands correlate well with measured stream discharge. While similar, our methodology relies on significantly higher resolution imagery (30 m) and utilizes bands that are in the blue and near-infrared spectrum as opposed to previous studies using 250 m resolution imagery and spectral bands only in the near-infrared. Higher resolution imagery is necessary for streams where the source is a <span class="hlt">glacier</span>'s terminus because the width of the stream is often only 10s of meters. We validate our methodology using two rivers in the state of Kansas, where stream gauges are plentiful. We then apply our method to the Bhagirathi River, in the North-Central Himalayas, which is fed by the Gangotri <span class="hlt">Glacier</span> and has a well monitored stream gauge. The analysis will later be used to couple river discharge and <span class="hlt">glacier</span> flow and mass balance through an integrated hydrologic model in the Bhagirathi <span class="hlt">Basin</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-GSFC_20171208_Archive_e000507.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-GSFC_20171208_Archive_e000507.html"><span>Malaspina <span class="hlt">Glacier</span>, Alaska</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-08</p> <p>The ice of a piedmont <span class="hlt">glacier</span> spills from a steep valley onto a relatively flat plain, where it spreads out unconstrained like pancake batter. Elephant Foot <span class="hlt">Glacier</span> in northeastern Greenland is an excellent example; it is particularly noted for its symmetry. But the largest piedmont <span class="hlt">glacier</span> in North America (and possibly the world) is Malaspina in southeastern Alaska. On September 24, 2014, the Operational Land Imager (OLI) on Landsat 8 acquired this image of Malaspina <span class="hlt">Glacier</span>. The main source of ice comes from Seward <span class="hlt">Glacier</span>, located at the top-center of this image. The Agassiz and Libbey <span class="hlt">glaciers</span> are visible on the left side, and the Hayden and Marvine <span class="hlt">glaciers</span> are on the right. The brown lines on the ice are moraines—areas where soil, rock, and other debris have been scraped up by the <span class="hlt">glacier</span> and deposited at its sides. Where two <span class="hlt">glaciers</span> flow together, the moraines merge to form a medial moraine. <span class="hlt">Glaciers</span> that flow at a steady speed tend to have moraines that are relatively straight. But what causes the dizzying pattern of curves, zigzags, and loops of Malaspina’s moraines? <span class="hlt">Glaciers</span> in this area of Alaska periodically “surge,”meaning they lurch forward quickly for one to several years. As a result of this irregular flow, the moraines at the edges and between <span class="hlt">glaciers</span> can become folded, compressed, and sheared to form the characteristic loops seen on Malaspina. For instance, a surge in 1986 displaced moraines on the east side of Malaspina by as much as 5 kilometers (3 miles). NASA Earth Observatory image by Jesse Allen, using Landsat data from the U.S. Geological Survey. Caption by Kathryn Hansen. Credit: NASA Earth Observatory NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70026130','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70026130"><span>Bedload component of glacially discharged sediment: Insights from the Matanuska <span class="hlt">Glacier</span>, Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Pearce, J.T.; Pazzaglia, F.J.; Evenson, E.B.; Lawson, D.E.; Alley, R.B.; Germanoski, D.; Denner, J.D.</p> <p>2003-01-01</p> <p>The flux of glacially derived bedload and the proportions of the suspended and bedload components carried by proglacial streams are highly debated. Published data indicate a large range-from 75%-in the bedload percentage of the total load. Two "vents," where supercooled subglacial meltwater and sediment are discharged, were sampled over the course of an entire melt season in order to quantify the flux of glacially delivered bedload at the Matanuska <span class="hlt">Glacier</span>, Alaska. The bedload component contributed by these vents, for the one melt season monitored, is negligible. Furthermore, the bedload fluxes appear to be strongly supply limited, as shown by the poorly correlated discharge, bedload-flux magnitude, and grain-size caliber. Thus, in this case, any attempt to employ a predictive quantitative expression for coarse-sediment production based on discharge alone would be inaccurate. A nonglaciated <span class="hlt">basin</span> proximal to the Matanuska <span class="hlt">Glacier</span> terminus yielded higher bedload sediment fluxes and larger clast sizes than delivered by the two monitored vents. Such nonglaciated <span class="hlt">basins</span> should not be overlooked as potentially major sources of coarse bedload that is reworked and incorporated into valley outwash.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C41B1210J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C41B1210J"><span>Sensitivity of <span class="hlt">Glacier</span> Mass Balance Estimates to the Selection of WRF Cloud Microphysics Parameterization in the Indus River Watershed</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Johnson, E. S.; Rupper, S.; Steenburgh, W. J.; Strong, C.; Kochanski, A.</p> <p>2017-12-01</p> <p>Climate model outputs are often used as inputs to <span class="hlt">glacier</span> energy and mass balance models, which are essential glaciological tools for testing <span class="hlt">glacier</span> sensitivity, providing mass balance estimates in regions with little glaciological data, and providing a means to model future changes. Climate model outputs, however, are sensitive to the choice of physical parameterizations, such as those for cloud microphysics, land-surface schemes, surface layer options, etc. Furthermore, <span class="hlt">glacier</span> mass balance (MB) estimates that use these climate model outputs as inputs are likely sensitive to the specific parameterization schemes, but this sensitivity has not been carefully assessed. Here we evaluate the sensitivity of <span class="hlt">glacier</span> MB estimates across the Indus <span class="hlt">Basin</span> to the selection of cloud microphysics parameterizations in the Weather Research and Forecasting Model (WRF). Cloud microphysics parameterizations differ in how they specify the size distributions of hydrometeors, the rate of graupel and snow production, their fall speed assumptions, the rates at which they convert from one hydrometeor type to the other, etc. While <span class="hlt">glacier</span> MB estimates are likely sensitive to other parameterizations in WRF, our preliminary results suggest that <span class="hlt">glacier</span> MB is highly sensitive to the timing, frequency, and amount of snowfall, which is influenced by the cloud microphysics parameterization. To this end, the Indus <span class="hlt">Basin</span> is an ideal study site, as it has both westerly (winter) and monsoonal (summer) precipitation influences, is a data-sparse region (so models are critical), and still has lingering questions as to <span class="hlt">glacier</span> importance for local and regional resources. WRF is run at a 4 km grid scale using two commonly used parameterizations: the Thompson scheme and the Goddard scheme. On average, these parameterizations result in minimal differences in annual precipitation. However, localized regions exhibit differences in precipitation of up to 3 m w.e. a-1. The different schemes also impact the</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.C13C0830H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.C13C0830H"><span>A new <span class="hlt">Glacier</span> Inventory of the Antarctic Peninsula as compiled from pre-existing Datasets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huber, J.; Cook, A. J.; Paul, F.; Zemp, M.</p> <p>2016-12-01</p> <p>The <span class="hlt">glaciers</span> on the Antarctic Peninsula (AP) potentially make a large contribution to sea level rise. However, this contribution was difficult to estimate, as no complete <span class="hlt">glacier</span> inventory (outlines, attributes, separation from the ice sheet) was available so far. This work fills the gap and presents a new <span class="hlt">glacier</span> inventory of the AP north of 70° S based on digitally combining pre-existing datasets with GIS techniques. Rock outcrops are removed from the <span class="hlt">glacier</span> <span class="hlt">basin</span> outlines of Cook et al. (2014) by digital intersection with the latest layer of the Antarctic Digital Database (Burton-Johnson et al. 2016). <span class="hlt">Glacier</span>-specific topographic parameters (e.g. mean elevation, slope and aspect) as well as hypsometry have been calculated from the DEM of Cook et al. (2012). We also assigned connectivity levels to all <span class="hlt">glaciers</span> following the concept by Rastner et al. (2012). Moreover, the bedrock dataset of Huss and Farinotti (2014) enabled us to add ice thickness and volume for each <span class="hlt">glacier</span>. The new inventory is available from the GLIMS database and consists of 1589 <span class="hlt">glaciers</span> covering an area of 95273 km2, slightly more than the 90000 km2 covered by <span class="hlt">glaciers</span> surrounding the Greenland Ice Sheet. The total ice volume is 34590 km3 of which 1/3 is below sea level. The hypsometric curve has a bimodal shape due to the special topography of the AP consisting mainly of ice caps with outlet <span class="hlt">glaciers</span>. Most of the <span class="hlt">glacierized</span> area is located at 200-500 m a.s.l. with a secondary maximum at 1500-1900 m. About 63% of the area is drained by marine-terminating <span class="hlt">glaciers</span> and ice shelf tributary <span class="hlt">glaciers</span> cover 35% of the area. This combination results in a high sensitivity of the <span class="hlt">glaciers</span> to climate change for several reasons: (1) only slightly rising equilibrium line altitudes would expose huge additional areas to ablation, (2) rising ocean temperatures increase melting of marine terminating <span class="hlt">glaciers</span>, and (3) ice shelves have a buttressing effect on their feeding <span class="hlt">glaciers</span> and their collapse would</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25123485','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25123485"><span><span class="hlt">Glaciers</span>. Attribution of global <span class="hlt">glacier</span> mass loss to anthropogenic and natural causes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Marzeion, Ben; Cogley, J Graham; Richter, Kristin; Parkes, David</p> <p>2014-08-22</p> <p>The ongoing global <span class="hlt">glacier</span> retreat is affecting human societies by causing sea-level rise, changing seasonal water availability, and increasing geohazards. Melting <span class="hlt">glaciers</span> are an icon of anthropogenic climate change. However, <span class="hlt">glacier</span> response times are typically decades or longer, which implies that the present-day <span class="hlt">glacier</span> retreat is a mixed response to past and current natural climate variability and current anthropogenic forcing. Here we show that only 25 ± 35% of the global <span class="hlt">glacier</span> mass loss during the period from 1851 to 2010 is attributable to anthropogenic causes. Nevertheless, the anthropogenic signal is detectable with high confidence in <span class="hlt">glacier</span> mass balance observations during 1991 to 2010, and the anthropogenic fraction of global <span class="hlt">glacier</span> mass loss during that period has increased to 69 ± 24%. Copyright © 2014, American Association for the Advancement of Science.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/36457','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/36457"><span>Examining incentives for <span class="hlt">adjacent</span> <span class="hlt">non</span>-industrial private forest landowners to cooperate</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Melinda Vokoun; Gregory S Amacher; Jay Sullivan; Dave Wear</p> <p>2010-01-01</p> <p>Individual landowners may capture <span class="hlt">non</span>-timber benefits from both their own forested parcels and <span class="hlt">adjacent</span> parcels owned by different landowners. These benefits may affect incentives for landowners to cooperate in their forest management decisions. Landowner survey data is used to examine incentives to cooperate concerning joint forest management and coordination of...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1912518P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1912518P"><span>Influencing factors on the cooling effect of coarse blocky top-layers on relict rock <span class="hlt">glaciers</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pauritsch, Marcus; Wagner, Thomas; Mayaud, Cyril; Thalheim, Felix; Kellerer-Pirklbauer, Andreas; Winkler, Gerfried</p> <p>2017-04-01</p> <p>Coarse blocky material widely occurs in alpine landscapes particularly at the surface of bouldery rock <span class="hlt">glaciers</span>. Such blocky layers are known to have a cooling effect on the subjacent material because of the enhanced <span class="hlt">non</span>-conductive heat exchange with the atmosphere. This effect is used for instance by the construction of blocky embankments in the building of railways and roads in permafrost regions to prevent thawing processes. In alpine regions, this cooling effect may have a strong influence on the distribution and conservation of permafrost related to climate warming. The thermal regimes of the blocky surface layers of two comparable - in terms of size, elevation and geology - relict rock <span class="hlt">glaciers</span> with opposing slope aspects are investigated. Therefore, the influence of the slope aspect-related climatic conditions (mainly the incident solar radiation, wind conditions and snow cover) on the cooling effect of the blocky layers is investigated. Air temperature, ground surface temperature and ground temperature at one meter depth were continuously measured over a period of four years at several locations at the NE-oriented Schöneben Rock <span class="hlt">Glacier</span> and the <span class="hlt">adjacent</span> SW-oriented Dürrtal Rock <span class="hlt">Glacier</span>. At the former, additional data about wind speed and wind direction as well as precipitation are available, which are used to take wind-forced convection and snow cover into consideration. Statistical analyses of the data reveal that the blocky top layer of the Dürrtal Rock <span class="hlt">Glacier</span> generally exhibits lower temperatures compared to the Schöneben Rock <span class="hlt">Glacier</span> despite the more radiation-exposed aspect and the related higher solar radiation. However, the data show that the thermal regimes of the surface layers are highly heterogeneous and that data from the individual measurement sites have to be interpreted with caution. High Rayleigh numbers at both rock <span class="hlt">glaciers</span> show that free convection occurs particularly during winter. Furthermore, wind-forced convection has a high</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.H11B1247E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.H11B1247E"><span>The geomorphic impact of catastrophic <span class="hlt">glacier</span> ice loss in mountain regions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Evans, S. G.</p> <p>2006-12-01</p> <p> <span class="hlt">adjacent</span> <span class="hlt">glacier</span> ice. In the Nostetuko case, the analysis of large-scale digital elevation models indicate that the outburst of 6.5 M m3 of water was initiated by a 1.5 M m3 <span class="hlt">glacier</span> avalanche from Cumberland <span class="hlt">Glacier</span> which initiated the breach. 1.6 M m3 of moraine was removed during the sudden breach and injected into the headwaters of the Nostetuko River. Thirdly, an attempt is made to quantify the increase in denudation and related sediment flux in mountain landscapes subject to catastrophic <span class="hlt">glacier</span>-ice loss.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMOS31D1659S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMOS31D1659S"><span>Seismic Stratigraphic Evidence From SE Ross Sea for Late Oligocene <span class="hlt">Glaciers</span> and ice Streams Issuing From Marie Byrd Land</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sorlien, C. C.; Luyendyk, B. P.; Wilson, D. S.; Decesari, R. C.; Bartek, L. R.; Diebold, J. B.</p> <p>2006-12-01</p> <p>The extent of the West Antarctic ice sheet during mid-Cenozoic time is controversial and important to climate models. High-resolution multichannel seismic reflection data were acquired using the RVIB Palmer along the edge of the Ross Ice Shelf across the Eastern <span class="hlt">Basin</span> of Ross Sea, in an area where calving of the ice shelf has exposed seafloor that has not been accessible to marine geophysics in several decades. A sub-<span class="hlt">basin</span> in the far southeast corner of Ross Sea contains a succession of sediment-filled troughs, each capped by an unconformity. These troughs range between 2 and 20 km across, are 100 to 150 m-deep, with the narrower ones bounded by flat-topped ridges interpreted as moraines. We interpret the troughs interval to slightly predate 25 Ma. Reflections just 100 m below the troughs interval can be directly correlated to near DSDP270 where they underlie strata dated at ~25 Ma. A deeper stack of prograding sequences associated with a flat- topped ridge are interpreted as pre-25 Ma, possibly early Oligocene, deltas formed <span class="hlt">adjacent</span> to the grounding line of a <span class="hlt">glacier</span>, and the flat-topped ridge to be a moraine. The shallowest of the stack of unconformities capping the broad troughs can be projected across a basement ridge on trend with Roosevelt Island to a regional angular unconformity ("Red"), present across 70 km to deep sedimentary Eastern <span class="hlt">Basin</span>. This unconformity represents about 1 km of missing stratigraphic section, is smooth and level, and splits into several major sequence boundaries within deep Eastern <span class="hlt">Basin</span>. The second shallowest of these boundaries is dated about 14 Ma at DSDP-270. We interpret this unconformity to be cut by regional thick, grounded ice at depths several hundred meters below sea level. Pre-25 Ma strata show evidence of narrow erosional troughs and reflective mounds or ridges on the west flank of the basement ridge, but such features are not present in southern deep Eastern <span class="hlt">Basin</span> near the ice shelf edge. This is evidence that the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70168968','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70168968"><span>The differing biogeochemical and microbial signatures of <span class="hlt">glaciers</span> and rock <span class="hlt">glaciers</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Fegel, Timothy S.; Baron, Jill S.; Fountain, Andrew G.; Johnson, Gunnar F.; Hall, Edward K.</p> <p>2016-01-01</p> <p><span class="hlt">Glaciers</span> and rock <span class="hlt">glaciers</span> supply water and bioavailable nutrients to headwater mountain lakes and streams across all regions of the American West. Here we present a comparative study of the metal, nutrient, and microbial characteristics of glacial and rock glacial influence on headwater ecosystems in three mountain ranges of the contiguous U.S.: The Cascade Mountains, Rocky Mountains, and Sierra Nevada. Several meltwater characteristics (water temperature, conductivity, pH, heavy metals, nutrients, complexity of dissolved organic matter (DOM), and bacterial richness and diversity) differed significantly between <span class="hlt">glacier</span> and rock <span class="hlt">glacier</span> meltwaters, while other characteristics (Ca2+, Fe3+, SiO2 concentrations, reactive nitrogen, and microbial processing of DOM) showed distinct trends between mountain ranges regardless of meltwater source. Some characteristics were affected both by <span class="hlt">glacier</span> type and mountain range (e.g. temperature, ammonium (NH4+) and nitrate (NO3- ) concentrations, bacterial diversity). Due to the ubiquity of rock <span class="hlt">glaciers</span> and the accelerating loss of the low latitude <span class="hlt">glaciers</span> our results point to the important and changing influence that these frozen features place on headwater ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1513236H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1513236H"><span>Climate sensitivity of Tibetan Plateau <span class="hlt">glaciers</span> - past and future implications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heyman, Jakob; Hubbard, Alun; Stroeven, Arjen P.; Harbor, Jonathan M.</p> <p>2013-04-01</p> <p>The Tibetan Plateau is one of the most extensively glaciated, <span class="hlt">non</span>-Polar regions of the world, and its mountain <span class="hlt">glaciers</span> are the primary source of melt water for several of the largest Asian rivers. During glacial cycles, Tibetan Plateau <span class="hlt">glaciers</span> advanced and retreated multiple times, but remained restricted to the highest mountain areas as valley <span class="hlt">glaciers</span> and ice caps. Because <span class="hlt">glacier</span> extent is dominantly controlled by climate, the past extent of Tibetan <span class="hlt">glaciers</span> provide information on regional climate. Here we present a study analyzing the past maximum extents of <span class="hlt">glaciers</span> on the Tibetan Plateau with the output of a 3D <span class="hlt">glacier</span> model, in an effort to quantify Tibetan Plateau climate. We have mapped present-day <span class="hlt">glaciers</span> and glacial landforms deposited by formerly more extensive <span class="hlt">glaciers</span> in eight mountain regions across the Tibetan Plateau, allowing us to define present-day and past maximum <span class="hlt">glacier</span> outlines. Using a high-resolution (250 m) higher-order <span class="hlt">glacier</span> model calibrated against present-day <span class="hlt">glacier</span> extents, we have quantified the climate perturbations required to expand present-day <span class="hlt">glaciers</span> to their past maximum extents. We find that a modest cooling of at most 6°C for a few thousand years is enough to attain past maximum extents, even with 25-75% precipitation reduction. This evidence for limited cooling indicates that the temperature of the Tibetan Plateau remained relatively stable over Quaternary glacial cycles. Given the significant sensitivity to temperature change, the expectation is perhaps that a future warmer climate might result in intense <span class="hlt">glacier</span> reduction. We have tested this hypothesis and modeled the future <span class="hlt">glacier</span> development for the three mountain regions with the largest present-day <span class="hlt">glacier</span> cover using a projected warming of 2.8 to 6.2°C within 100 years (envelope limits from IPCC). These scenarios result in dramatic <span class="hlt">glacier</span> reductions, including 24-100% ice volume loss after 100 years and 77-100% ice volume loss after 300 years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70030545','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70030545"><span><span class="hlt">Glacier</span> mass-balance fluctuations in the Pacific Northwest and Alaska, USA</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Josberger, E.G.; Bidlake, W.R.; March, R.S.; Kennedy, B.W.</p> <p>2007-01-01</p> <p>The more than 40 year record of net and seasonal mass-balance records from measurements made by the United States Geological Survey on South Cascade <span class="hlt">Glacier</span>, Washington, and Wolverine and Gulkana <span class="hlt">Glaciers</span>, Alaska, shows annual and interannual fluctuations that reflect changes in the controlling climatic conditions at regional and global scales. As the mass-balance record grows in length, it is revealing significant changes in previously described <span class="hlt">glacier</span> mass-balance behavior, and both inter-<span class="hlt">glacier</span> and <span class="hlt">glacier</span>-climate relationships. South Cascade and Wolverine <span class="hlt">Glaciers</span> are strongly affected by the warm and wet maritime climate of the northeast Pacific Ocean. Their net balances have generally been controlled by winter accumulation, with fluctuations that are strongly related to the Pacific Decadal Oscillation (PDO). Recently, warm dry summers have begun to dominate the net balance of the two maritime <span class="hlt">glaciers</span>, with a weakening of the correlation between the winter balance fluctuations and the PDO. <span class="hlt">Non</span>-synchronous periods of positive and negative net balance for each <span class="hlt">glacier</span> prior to 1989 were followed by a 1989-2004 period of synchronous and almost exclusively negative net balances that averaged -0.8 m for the three <span class="hlt">glaciers</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C11E..08R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C11E..08R"><span>Himalayan <span class="hlt">glaciers</span>: understanding contrasting patterns of <span class="hlt">glacier</span> behavior using multi-temporal satellite imagery</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Racoviteanu, A.</p> <p>2014-12-01</p> <p>High rates of <span class="hlt">glacier</span> retreat for the last decades are often reported, and believed to be induced by 20th century climate changes. However, regional <span class="hlt">glacier</span> fluctuations are complex, and depend on a combination of climate and local topography. Furthermore, in ares such as the Hindu-Kush Himalaya, there are concerns about warming, decreasing monsoon precipitation and their impact on local <span class="hlt">glacier</span> regimes. Currently, the challenge is in understanding the magnitude of feedbacks between large-scale climate forcing and small-scale <span class="hlt">glacier</span> behavior. Spatio-temporal patterns of <span class="hlt">glacier</span> distribution are still llimited in some areas of the high Hindu-Kush Himalaya, but multi-temporal satellite imagery has helped fill spatial and temporal gaps in regional <span class="hlt">glacier</span> parameters in the last decade. Here I present a synopsis of the behavior of <span class="hlt">glaciers</span> across the Himalaya, following a west to east gradient. In particular, I focus on spatial patterns of <span class="hlt">glacier</span> parameters in the eastern Himalaya, which I investigate at multi-spatial scales using remote sensing data from declassified Corona, ASTER, Landsat ETM+, Quickbird and Worldview2 sensors. I also present the use of high-resolution imagery, including texture and thermal analysis for mapping <span class="hlt">glacier</span> features at small scale, which are particularly useful in understanding surface trends of debris-covered <span class="hlt">glaciers</span>, which are prevalent in the Himalaya. I compare and contrast spatial patterns of <span class="hlt">glacier</span> area and élévation changes in the monsoon-influenced eastern Himalaya (the Everest region in the Nepal Himalaya and Sikkim in the Indian Himalaya) with other observations from the dry western Indian Himalaya (Ladakh and Lahul-Spiti), both field measurements and remote sensing-based. In the eastern Himalaya, results point to <span class="hlt">glacier</span> area change of -0.24 % ± 0.08% per year from the 1960's to the 2006's, with a higher rate of retreat in the last decade (-0.43% /yr). Debris-covered <span class="hlt">glacier</span> tongues show thinning trends of -30.8 m± 39 m</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70018159','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70018159"><span>20th-century glacial-marine sedimentation in Vitus Lake, Bering <span class="hlt">Glacier</span>, Alaska, U.S.A.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Molnia, B.F.; Post, A.; Carlson, P.R.</p> <p>1996-01-01</p> <p>Vitus Lake, the ice-marginal <span class="hlt">basin</span> at the southeastern edge of Bering <span class="hlt">Glacier</span>, Alaska, U.S.A., is a site of modern, rapid, glacial-marine sedimentation. Rather than being a fresh-water lake, Vitus Lake is a tidally influenced, marine to brackish embayment connected to the Pacific Ocean by an inlet, the Seal River. Vitus Lake consists of five deep bedrock <span class="hlt">basins</span>, separated by interbasinal highs. Glacial erosion has cut these <span class="hlt">basins</span> as much as 250 m below sea level. High-resolution seismic reflection surveys conducted in 1991 and 1993 of four of Vitus Lake's <span class="hlt">basins</span> reveal a complex, variable three-component acoustic stratigraphy. Although not fully sampled, the stratigraphy is inferred to be primarily glacial-marine units of (1) basal contorted and deformed glacial-marine and glacial sediments deposited by basal ice-contact processes and submarine mass-wasting; (2) acoustically well-stratified glacial-marine sediment, which unconformably overlies the basal unit and which grades upward into (3) acoustically transparent or nearly transparent glacial-marine sediment. Maximum thicknesses of conformable glacial-marine sediment exceed 100 m. All of the acoustically transparent and stratified deposits in Vitus Lake are modern in age, having accumulated between 1967 and 1993. The <span class="hlt">basins</span> where these three-part sequences of "present-day" glacial-marine sediment are accumulating are themselves cut into older sequences of stratified glacial and glacial-marine deposits. These older units outcrop on the islands in Vitus Lake. In 1967, as the result of a major surge, <span class="hlt">glacier</span> ice completely filled all five <span class="hlt">basins</span>. Subsequent terminus retreat, which continued through August 1993, exposed these <span class="hlt">basins</span>, providing new locations for glacial-marine sediment accumulation. A correlation of sediment thicknesses measured from seismic profiles at specific locations within the <span class="hlt">basins</span>, with the year that each location became ice-free, shows that the sediment accumulation at some locations</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.H11D..03S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.H11D..03S"><span>Quantifying changes in the contribution of upstream snow and <span class="hlt">glacier</span> melt to downstream low flows in the River Rhine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stahl, K.; Kohn, I.; Boehm, M.; Seibert, J.; Freudiger, D.; Gerlinger, K.; Weiler, M.</p> <p>2016-12-01</p> <p>Low flows impact river ecosystems and impair water use. In the mid- and downstream reaches of one of the largest rivers in Europe, the River Rhine, low flows can threaten a variety of ecosystem services and direct uses. Low flows in summer and fall are sustained by the snow and ice melt contribution from the <span class="hlt">glacierized</span> mountain headwaters upstream. This study explores changes in the discharge components of rain, snowmelt and ice melt during extreme low flow events from a downstream perspective. Quantification of the discharge components is based on a novel method of runoff component tracking that was implemented into a model chain, consisting of the HBV model, which includes a <span class="hlt">glacier</span> mass balance model allowing for areal <span class="hlt">glacier</span> changes, for the headwaters and the distributed hydrological model LARSIM for the remaining Rhine <span class="hlt">basin</span>. A transient model run at daily resolution was calibrated to <span class="hlt">glacier</span> volume change, <span class="hlt">basin</span>-wide snow cover and snow water equivalent and discharge variability at many gauging stations over the period 1901-2006. The analysis of the resulting discharge components revealed that over the course of the 20th Century, the loss of <span class="hlt">glacier</span> volume and <span class="hlt">glacier</span> area in the headwaters appears to have compensated an increasingly negative <span class="hlt">glacier</span> mass balance, resulting in little long-term change to the ice melt component in summer streamflow - thus showing no clear `peak-water' trend. While the <span class="hlt">glacier</span> ice melt component was less than two percent of the average annual discharge of the mid and lower reaches of the River Rhine, models suggest its fraction was much higher during extreme low flow events. The low flows of the summers of 1921, 1947, and 2003 were comprised of record daily ice melt fractions of more than one fifth of the daily discharge along the mid and lower reaches from Basel to the mouth. A scenario model run with suppressed <span class="hlt">glacier</span> area change suggests that the ice melt discharge component would have doubled if the same meteorological</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.C41D0696C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.C41D0696C"><span>Hydrological response in catchments whit debris covered <span class="hlt">glaciers</span> in the semi-arid Andes, Chile</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caro, A.; McPhee, J.; MacDonell, S.; Pellicciotti, F.; Ayala, A.</p> <p>2016-12-01</p> <p><span class="hlt">Glaciers</span> in the semi-arid Andes Cordillera in Chile have shrank rapidly during the 20th century. Negative mass balance contributes to increase the surface area of debris-covered <span class="hlt">glaciers</span>. Recent research in Chile suggests that contributions from <span class="hlt">glaciers</span> to summer season river flow in dry years is very important, however hydrological processes determining the <span class="hlt">glacier</span> contribution are still poorly understood in the region. This work seeks to determine appropriate parameters for the simulation of melt volume in two watersheds dominated by debris-covered <span class="hlt">glaciers</span>, in order to understand its variability in time and space, in the area with the largest population in Chile. The hydrological simulation is performed for the Tapado (30°S) and Pirámide (33ºS) <span class="hlt">glaciers</span>, which can be defined as cold and temperate respectively. To simulate the hydrological behaviour we adopt the physically-based TOPographic Kinematic wave APproximation model (TOPKAPI-ETH). The hydrometeorological records necessary model runs have been collected through fieldwork from 2013 to 2015. Regarding the calibration of the model parameters melting ETI, its observed that the value for TF in Pirámide is a third of the value for Tapado <span class="hlt">glacier</span>, while SRF is half in Tapado regarding to Pirámide. The runoff in the <span class="hlt">glaciers</span>, the constant snow and ice storage are higher in Tapado regarding Pirámide. Results show a contribution of glacial outflow to runoff during 2015 of 55% in Tapado and 77% in Pirámide, with maximum contributions between January and March in Tapado and Pirámide between November and March, presenting the relevance of the permanence of snow cover during spring and shelter that provides debris-covered in reducing the melting <span class="hlt">glacier</span>. The results have allowed to know the relevance of the <span class="hlt">glacier</span> contribution to mountain streams, allowing to know the calibration parameters most relevant in the hydrology balance of <span class="hlt">glacier</span> <span class="hlt">basins</span> in the Andes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014E%26PSL.399...52S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014E%26PSL.399...52S"><span>Active water exchange and life near the grounding line of an Antarctic outlet <span class="hlt">glacier</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sugiyama, Shin; Sawagaki, Takanobu; Fukuda, Takehiro; Aoki, Shigeru</p> <p>2014-08-01</p> <p>The grounding line (GL) of the Antarctic ice sheet forms the boundary between grounded and floating ice along the coast. Near this line, warm oceanic water contacts the ice shelf, producing the ice sheet's highest basal-melt rate. Despite the importance of this region, water properties and circulations near the GL are largely unexplored because in-situ observations are difficult. Here we present direct evidence of warm ocean-water transport to the innermost part of the subshelf cavity (several hundred meters seaward from the GL) of Langhovde <span class="hlt">Glacier</span>, an outlet <span class="hlt">glacier</span> in East Antarctica. Our measurements come from boreholes drilled through the <span class="hlt">glacier</span>'s ∼400-m-thick grounding zone. Beneath the grounding zone, we find a 10-24-m-deep water layer of uniform temperature and salinity (-1.45 °C; 34.25 PSU), values that roughly equal those measured in the ocean in front of the <span class="hlt">glacier</span>. Moreover, living organisms are found in the thin subglacial water layer. These findings indicate active transport of water and nutrients from the <span class="hlt">adjacent</span> ocean, meaning that the subshelf environment interacts directly and rapidly with the ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27.4979G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27.4979G"><span>Modelling The Energy And Mass Balance Of A Black <span class="hlt">Glacier</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grossi, G.; Taschner, S.; Ranzi, R.</p> <p></p> <p>A distributed energy balance hydrologic model has been implemented to simulate the melting season of the Belvedere <span class="hlt">glacier</span>, situated in the Anza river <span class="hlt">basin</span> (North- Western Italy) for a few years. The Belvedere <span class="hlt">Glacier</span> is an example of SblackS <span class="hlt">glacier</span>, ´ since the ablation zone is covered by a significant debris layer. The <span class="hlt">glacier</span>Ss termi- nus has an altitude of 1785 m asl which is very unusual for the Southern side of the European Alps. The model accounts for the energy exchange processes at the inter- face between the atmospheric boundary layer and the snow/ice/debris layer. To run the model hydrometeorological and physiographic data were collected, including the depth of the debris cover and the tritium (3H) concentration in the glacial river. Mea- surements of the soil thermal conductivity were carried out during a field campaign organised within the <span class="hlt">glaciers</span> monitoring GLIMS project, at the time of the passage of the Landsat and the Terra satellites last 15 August 2001. A comparison of the different energy terms simulated by the model assigns a dominant role to the shortwave radia- tion, which provides the highest positive contribution to the energy available for snow- and ice-melt, while the sensible heat turns out to be the second major source of heat. Longwave radiation balance and latent heat seem to be less relevant and often nega- tive. The role of the debris cover is not negligible, since its thermal insulation causes, on average, a decrease in the ice melt volume. One of the model variables is the tem- perature of the debris cover, which can be a useful information when a black <span class="hlt">glacier</span> is to be monitored through remote sensing techniques. The visible and near infrared radi- ation data do not always provide sufficient information to detect the <span class="hlt">glaciers</span>' margins beneath the debris layer. For this reason the information of the different thermal sur- face characteristics (pure ice, debris covered ice, rock), proved by the energy balance model results was</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C11E..02J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C11E..02J"><span>Rapid Holocene thinning of outlet <span class="hlt">glaciers</span> followed by readvance in the western Ross Embayment, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jones, R. S.; Whitmore, R.; Mackintosh, A.; Norton, K. P.; Eaves, S.; Stutz, J.</p> <p>2017-12-01</p> <p>Investigating Antarctic deglaciation following the LGM provides an opportunity to better understand patterns, mechanisms and drivers of ice sheet retreat. In the Ross Sea sector, geomorphic features preserved on the seafloor indicate that streaming East Antarctic outlet <span class="hlt">glaciers</span> once extended >100 km offshore of South Victoria Land prior to back-stepping towards their modern configurations. In order to adequately interpret the style and causes of this retreat, the timing and magnitude of corresponding ice thickness change is required. We present new constraints on ice surface lowering from Mawson <span class="hlt">Glacier</span>, an outlet of the East Antarctic Ice Sheet that flows into the western Ross Sea. Surface-exposure (10Be) ages from samples collected in elevation transects above the modern ice surface reveal that rapid thinning occurred at 5-8 ka, broadly coeval with new ages of grounding-line retreat at 6 ka and rapid thinning recorded at nearby Mackay <span class="hlt">Glacier</span> at 7 ka. Our data also show that a moraine formed near to the modern ice margin of Mawson <span class="hlt">Glacier</span> at 0.8 ka, which, together with historical observations, indicates that <span class="hlt">glaciers</span> in this region readvanced during the last thousand years. We argue that 1) the accelerated thinning of outlet <span class="hlt">glaciers</span> was driven by local grounding-line retreat through overdeepened <span class="hlt">basins</span> during the early-mid Holocene, and 2) the <span class="hlt">glaciers</span> subsequently readvanced, possibly linked to late Holocene sea-ice expansion, before retreating to their current positions. Our work demonstrates that these outlet <span class="hlt">glaciers</span> were closely coupled to environmental and topography-induced perturbations near their termini throughout the Holocene.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013TCD.....7.5579C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013TCD.....7.5579C"><span>Ocean properties, ice-ocean interactions, and calving front morphology at two major west Greenland <span class="hlt">glaciers</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chauché, N.; Hubbard, A.; Gascard, J.-C.; Box, J. E.; Bates, R.; Koppes, M.; Sole, A.; Patton, H.</p> <p>2013-11-01</p> <p>Warm sub-polar mode water (SPMW) has been identified as a primary driver of mass loss of marine terminating <span class="hlt">glaciers</span> draining the Greenland Ice Sheet (GrIS) yet, the specific mechanisms by which SPMW interacts with these tidewater termini remain uncertain. We present oceanographic data from Rink <span class="hlt">Glacier</span> (RG) and Store <span class="hlt">Glacier</span> (SG) fjords, two major marine outlets draining the western sector of the GrIS into Baffin Bay over the contrasting melt-seasons of 2009 and 2010. Submarine melting occurs wherever ice is in direct contact with warmer water and the consistent presence of 2.8 °C SPMW <span class="hlt">adjacent</span> to both ice fronts below 400 m throughout all surveys indicates that melting is maintained by a combination of molecular diffusion and large scale, weak convection, diffusional (hereafter called ubiquitous) melting. At shallower depths (50-200 m), cold, brine-enriched water (BEW) formed over winter appears to persist into the summer thereby buffering this melt by thermal insulation. Our surveys reveal four main modes of <span class="hlt">glacier</span>-ocean interaction, governed by water depth and the rate of <span class="hlt">glacier</span> runoff water (GRW) injected into the fjord. Deeper than 200 m, submarine melt is the only process observed, regardless of the intensity of GRW or the depth of injection. However, between the surface and 200 m depth, three further distinct modes are observed governed by the GRW discharge. When GRW is weak (≲1000 m3 s-1), upward motion of the water <span class="hlt">adjacent</span> to the <span class="hlt">glacier</span> front is subdued, weak forced or free convection plus diffusional submarine melting dominates at depth, and seaward outflow of melt water occurs from the <span class="hlt">glacier</span> toe to the base of the insulating BEW. During medium intensity GRW (∼1500 m3 s-1), mixing with SPMW yields deep mixed runoff water (DMRW), which rises as a buoyant plume and intensifies local submarine melting (enhanced buoyancy-driven melting). In this case, DMRW typically attains hydrostatic equilibrium and flows seaward at an intermediate depth of </p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70162624','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70162624"><span>Presence and abundance of <span class="hlt">non</span>-native plant species associated with recent energy development in the Williston <span class="hlt">Basin</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Preston, Todd M.</p> <p>2015-01-01</p> <p>The Williston <span class="hlt">Basin</span>, located in the Northern Great Plains, is experiencing rapid energy development with North Dakota and Montana being the epicenter of current and projected development in the USA. The average single-bore well pad is 5 acres with an estimated 58,485 wells in North Dakota alone. This landscape-level disturbance may provide a pathway for the establishment of <span class="hlt">non</span>-native plants. To evaluate potential influences of energy development on the presence and abundance of <span class="hlt">non</span>-native species, vegetation surveys were conducted at 30 oil well sites (14 ten-year-old and 16 five-year-old wells) and 14 control sites in native prairie environments across the Williston <span class="hlt">Basin</span>. <span class="hlt">Non</span>-native species richness and cover were recorded in four quadrats, located at equal distances, along four transects for a total of 16 quadrats per site. <span class="hlt">Non</span>-natives were recorded at all 44 sites and ranged from 5 to 13 species, 7 to 15 species, and 2 to 8 species at the 10-year, 5-year, and control sites, respectively. Respective <span class="hlt">non</span>-native cover ranged from 1 to 69, 16 to 76, and 2 to 82 %. Total, forb, and graminoid <span class="hlt">non</span>-native species richness and <span class="hlt">non</span>-native forb cover were significantly greater at oil well sites compared to control sites. At oil well sites, <span class="hlt">non</span>-native species richness and forb cover were significantly greater <span class="hlt">adjacent</span> to the well pads and decreased with distance to values similar to control sites. Finally, <span class="hlt">non</span>-native species whose presence and/or abundance were significantly greater at oil well sites relative to control sites were identified to aid management efforts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMEP41D..04A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMEP41D..04A"><span>Modeling the Rock <span class="hlt">Glacier</span> Cycle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Anderson, R. S.; Anderson, L. S.</p> <p>2016-12-01</p> <p>Rock <span class="hlt">glaciers</span> are common in many mountain ranges in which the ELA lies above the peaks. They represent some of the most identifiable components of today's cryosphere in these settings. Their oversteepened snouts pose often-overlooked hazards to travel in alpine terrain. Rock <span class="hlt">glaciers</span> are supported by avalanches and by rockfall from steep headwalls. The winter's avalanche cone must be sufficiently thick not to melt entirely in the summer. The spatial distribution of rock <span class="hlt">glaciers</span> reflects this dependence on avalanche sources; they are most common on lee sides of ridges where wind-blown snow augments the avalanche source. In the absence of rockfall, this would support a short, cirque <span class="hlt">glacier</span>. Depending on the relationship between rockfall and avalanche patterns, "talus-derived" and "<span class="hlt">glacier</span>-derived" rock <span class="hlt">glaciers</span> are possible. Talus-derived: If the spatial distribution of rock delivery is similar to the avalanche pattern, the rock-ice mixture will travel an englacial path that is downward through the short accumulation zone before turning upward in the ablation zone. Advected debris is then delivered to the base of a growing surface debris layer that reduces the ice melt rate. The physics is identical to the debris-covered <span class="hlt">glacier</span> case. <span class="hlt">Glacier</span>-derived: If on the other hand rockfall from the headwall rolls beyond the avalanche cone, it is added directly to the ablation zone of the <span class="hlt">glacier</span>. The avalanche accumulation zone then supports a pure ice core to the rock <span class="hlt">glacier</span>. We have developed numerical models designed to capture the full range of <span class="hlt">glacier</span> to debris-covered <span class="hlt">glacier</span> to rock <span class="hlt">glacier</span> behavior. The hundreds of meter lengths, tens of meters thicknesses, and meter per year speeds of rock <span class="hlt">glaciers</span> are well described by the models. The model can capture both "talus-derived" and "<span class="hlt">glacier</span>-derived" rock <span class="hlt">glaciers</span>. We explore the dependence of <span class="hlt">glacier</span> behavior on climate histories. As climate warms, a pure ice debris-covered <span class="hlt">glacier</span> can transform to a much shorter rock</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1910394W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1910394W"><span>Geoengineering Outlet <span class="hlt">Glaciers</span> and Ice Streams</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wolovick, Michael</p> <p>2017-04-01</p> <p>Mass loss from Greenland and Antarctica is highly sensitive to the presence of warm ocean water that drives melting of ice shelves and marine terminated <span class="hlt">glaciers</span>. This warm water resides offshore at depth and accesses the grounding line through deep but narrow troughs and fjords. Here, we investigate the possibility of blocking warm water transport through these choke points with an artificial sill. Using a simple width-averaged model of ice stream flow coupled to a buoyant-plume model of submarine melt, we find that grounding line retreat and sea level rise can be delayed or reversed for hundreds of years if warm water is prevented from accessing outlet <span class="hlt">glaciers</span> and ice-shelf cavities. <span class="hlt">Glaciers</span> with a floating shelf exhibit a strong response to the presence of the artificial sill regardless of our choice of calving law, while tidewater <span class="hlt">glaciers</span> require a strong linkage between submarine melt and iceberg calving for the artificial sill to have an effect. As a result of this difference and as a result of differing degrees of overdeepening in the basal topography, Antarctica and Greenland present very different societal cost-benefit analyses. Intervention in Greenland would be low-cost and low-reward: the volume of the artificial sill is comparable to existing large public works projects such as the Dubai Islands or the Suez Canal, but the magnitude of averted sea-level rise is small, the success of the intervention depends on the choice of calving law, and the <span class="hlt">glaciers</span> return to their <span class="hlt">non</span>-geoengineered trajectories within one to two centuries. Intervention in Antarctica, on the other hand, would be high-cost and high-reward: the volume of the artificial sill is one to two orders of magnitude greater, but the averted sea level rise is much larger, the intervention is successful regardless of the choice of calving law, and the ice streams remain far from their <span class="hlt">non</span>-geoengineered trajectories throughout the 1000 year duration of our model runs. In both cases, an</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.C41E0457P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.C41E0457P"><span>Airborne geophysical investigations of basal conditions at flow transitions of outlet <span class="hlt">glaciers</span> on the Greenland Ice Sheet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Palmer, S. J.; Dowdeswell, J. A.; Christoffersen, P.; Siegert, M. J.; Blankenship, D. D.; Young, D. A.; Greenbaum, J.</p> <p>2011-12-01</p> <p>Recent observations have shown that the fast flowing marine-terminating outlet <span class="hlt">glaciers</span> which drain the Greenland Ice Sheet (GrIS) have thinned in places at rates in excess of 10 m yr-1. The 21 largest outlet <span class="hlt">glaciers</span> in Greenland accelerated by 57 % between 1996 and 2005, leading to a 100 Gt yr-1 increase in mass loss due to ice discharge over the same period and a 150 % increase of the GrIS's contribution to sea level. Observations that thinning rates are greater than those expected from changes in surface mass balance alone suggest thinning of some GrIS marine-terminating outlet <span class="hlt">glaciers</span> can be attributed to changes in ice dynamics. An important question for both scientists and policy makers is how the GrIS will react to projected temperature increases, particularly in the context that the Arctic is likely to warm at a greater rate than the global average due to the ice-albedo feedback. As the combined width of all major marine-terminating <span class="hlt">glaciers</span> draining the GrIS (as measured at the narrowest point in each case) is less 200 km, an understanding of their dynamics is crucial in predicting the effect of future warming on the ice sheet as a whole. During April 2011, we used a Basler BT-67 aircraft equipped with a suite of geophysical instruments to investigate three major <span class="hlt">glacier</span> systems in Greenland. Data were acquired at the Sermeq Kujatdl and Rink <span class="hlt">Glacier</span> systems in West Greenland; and Daugaard Jensen <span class="hlt">Glacier</span> in East Greenland. The study areas were selected because they are major drainage <span class="hlt">basins</span> (c. 103-105 km2) which provide a high ice flux to the sea (c. 10-20 km3 yr-1); and are located in different regions of the GrIS with correspondingly different atmospheric and oceanic settings. Here we present results from the High Capability Radar Sounder instrument, a phase coherent VHF ice-penetrating radar which operates in frequency-chirped mode from 52.5 to 67.5 MHz. We use these data to determine ice thickness along flightlines both parallel and perpendicular to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-GSFC_20171208_Archive_e002000.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-GSFC_20171208_Archive_e002000.html"><span>Susitna <span class="hlt">Glacier</span>, Alaska</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-08</p> <p>NASA image acquired August 27, 2009 Like rivers of liquid water, <span class="hlt">glaciers</span> flow downhill, with tributaries joining to form larger rivers. But where water rushes, ice crawls. As a result, <span class="hlt">glaciers</span> gather dust and dirt, and bear long-lasting evidence of past movements. Alaska’s Susitna <span class="hlt">Glacier</span> revealed some of its long, grinding journey when the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite passed overhead on August 27, 2009. This satellite image combines infrared, red, and green wavelengths to form a false-color image. Vegetation is red and the glacier’s surface is marbled with dirt-free blue ice and dirt-coated brown ice. Infusions of relatively clean ice push in from tributaries in the north. The <span class="hlt">glacier</span> surface appears especially complex near the center of the image, where a tributary has pushed the ice in the main <span class="hlt">glacier</span> slightly southward. A photograph taken by researchers from the U.S. Geological Survey (archived by the National Snow and Ice Data Center) shows an equally complicated Susitna <span class="hlt">Glacier</span> in 1970, with dirt-free and dirt-encrusted surfaces forming stripes, curves, and U-turns. Susitna flows over a seismically active area. In fact, a 7.9-magnitude quake struck the region in November 2002, along a previously unknown fault. Geologists surmised that earthquakes had created the steep cliffs and slopes in the <span class="hlt">glacier</span> surface, but in fact most of the jumble is the result of surges in tributary <span class="hlt">glaciers</span>. <span class="hlt">Glacier</span> surges—typically short-lived events where a <span class="hlt">glacier</span> moves many times its normal rate—can occur when melt water accumulates at the base and lubricates the flow. This water may be supplied by meltwater lakes that accumulate on top of the <span class="hlt">glacier</span>; some are visible in the lower left corner of this image. The underlying bedrock can also contribute to <span class="hlt">glacier</span> surges, with soft, easily deformed rock leading to more frequent surges. NASA Earth Observatory image created by Jesse Allen and Robert</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.1168D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.1168D"><span>Controls and variability of solute and sedimentary fluxes in Arctic and sub-Arctic Environments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dixon, John</p> <p>2015-04-01</p> <p>Six major factors consistently emerge as controls on the spatial and temporal variability in sediment and solute fluxes in cold climates. They are climatic, geologic, physiographic or relief, biologic, hydrologic, and regolith factors. The impact of these factors on sediment and solute mass transfer in Arctic and sub-Arctic environments is examined. Comparison of <span class="hlt">non-glacierized</span> Arctic vs. subarctic drainage <span class="hlt">basins</span> reveals the effects of these controls. All drainage <span class="hlt">basins</span> exhibit considerable variability in rates of sediment and solute fluxes. For the <span class="hlt">non-glacierized</span> drainage <span class="hlt">basins</span> there is a consistent increase in sediment mass transfer by slope processes and fluvial processes as relief increases. Similarly, a consistent increase in sediment mass transfer by slope and fluvial processes is observed as total precipitation increases. Similar patterns are also observed with respect to solute transport and relief and precipitation. Lithologic factors are most strongly observed in the contrast between volcanic vs. plutonic igneous bedrock substrates. <span class="hlt">Basins</span> underlain by volcanic rocks display greater mass transfers than those underlain by plutonic rocks. Biologic influences are most strongly expressed by variations in extent of vegetation cover and the degree of human interference, with human impacted <span class="hlt">basins</span> generating greater fluxes. For <span class="hlt">glacierized</span> <span class="hlt">basins</span> the fundamental difference to <span class="hlt">non-glacierized</span> <span class="hlt">basins</span> is an overall increase in mean annual mass transfers of sediment and a generally smaller magnitude solute transfer. The principal role of geology is observed with respect to lithology. Catchments underlain by limestone demonstrate substantially greater solute mass transfers than sediment transfer. The influence of relief is seen in the contrast in mass transfers between upland and lowland drainage <span class="hlt">basins</span> with upland <span class="hlt">basins</span> generating greater sediment and solute transfers than lowland <span class="hlt">basins</span>. For <span class="hlt">glacierized</span> <span class="hlt">basins</span> the effects of biology and regolith appear to be</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C33D1236L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C33D1236L"><span>Geodetic mass balance measurements on debris and clean-ice tropical <span class="hlt">glaciers</span> in Ecuador</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>La Frenierre, J.; Decker, C. R.; Jordan, E.; Wigmore, O.; Hodge, B. E.; Niederriter, C.; Michels, A.</p> <p>2017-12-01</p> <p><span class="hlt">Glaciers</span> are recognized as highly sensitive indicators of climate change in high altitude, low latitude environments. In the tropical Andes, various analyses of <span class="hlt">glacier</span> surface area change have helped illuminate the manifestation of climate change in this region, however, information about actual <span class="hlt">glacier</span> mass balance behavior is much more limited given the relatively small <span class="hlt">glaciers</span>, difficult access, poor weather, and/or limited local resources common here. Several new technologies, including aerial and terrestrial LIDAR and structure-from-motion photogrammetry using small unmanned aerial vehicles (UAVs), make mass balance measurements using geodetic approaches increasingly feasible in remote mountain locations, which can both further our understanding of changing climatic conditions, and improve our ability to evaluate the downstream hydrologic impacts of ice loss. At Volcán Chimborazo, Ecuador, these new technologies, combined with a unique, 5-meter resolution digital elevation model derived from 1997 aerial imagery, make possible an analysis of the magnitude and spatial patterns of mass balance behavior over the past two decades. Here, we evaluate ice loss between 1997 and 2017 at the tongues of two <span class="hlt">adjacent</span> <span class="hlt">glaciers</span>, one debris-covered and detached from its accumulation area (Reschreiter <span class="hlt">Glacier</span>), and one debris-free and intact (Hans Meyer <span class="hlt">Glacier</span>). Additionally, we incorporate data from 2012 and 2013 terrestrial LIDAR surveys to evaluate the behavior of the Reschreiter at a finer temporal resolution. We find that on the Hans Meyer, the mean surface deflation rate since 1997 at the present-day tongue has been nearly 3 m yr-1, while on the lower-elevation Reschreiter, the mean deflation rate has been approximately 1 m yr-1. However, the processes by which debris-covered ice becomes exposed results in highly heterogeneous patterns of ice loss, with some areas experiencing surface deflation rates approaching 15 m yr-1 when energy absorption is unimpeded.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70025232','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70025232"><span>The slow advance of a calving <span class="hlt">glacier</span>: Hubbard <span class="hlt">Glacier</span>, Alaska, U.S.A</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Trabant, D.C.; Krimmel, R.M.; Echelmeyer, K.A.; Zirnheld, S.L.; Elsberg, D.H.</p> <p>2003-01-01</p> <p>Hubbard <span class="hlt">Glacier</span> is the largest tidewater <span class="hlt">glacier</span> in North America. In contrast to most <span class="hlt">glaciers</span> in Alaska and northwestern Canada, Hubbard <span class="hlt">Glacier</span> thickened and advanced during the 20th century. This atypical behavior is an important example of how insensitive to climate a <span class="hlt">glacier</span> can become during parts of the calving <span class="hlt">glacier</span> cycle. As this <span class="hlt">glacier</span> continues to advance, it will close the seaward entrance to 50 km long Russell Fjord and create a <span class="hlt">glacier</span>-dammed, brackish-water lake. This paper describes measured changes in ice thickness, ice speed, terminus advance and fjord bathymetry of Hubbard <span class="hlt">Glacier</span>, as determined from airborne laser altimetry, aerial photogrammetry, satellite imagery and bathymetric measurements. The data show that the lower regions of the <span class="hlt">glacier</span> have thickened by as much as 83 m in the last 41 years, while the entire <span class="hlt">glacier</span> increased in volume by 14.1 km3. Ice speeds are generally decreasing near the calving face from a high of 16.5 m d-1 in 1948 to 11.5 m d-1 in 2001. The calving terminus advanced at an average rate of about 16 m a-1 between 1895 and 1948 and accelerated to 32 m a-1 since 1948. However, since 1986, the advance of the part of the terminus in Disenchantment Bay has slowed to 28 m a-1. Bathymetric data from the lee slope of the submarine terminal moraine show that between 1978 and 1999 the moraine advanced at an average rate of 32 m a-1, which is the same as that of the calving face.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.2548M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.2548M"><span>The distribution and tectonic framework of Late Paleozoic volcanoes in the Junggar <span class="hlt">basin</span> and its <span class="hlt">adjacent</span> area, NW China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mao, X.; Li, J. H.</p> <p>2012-04-01</p> <p>We analyse the distribution and characteristics of 145 late Paleozoic volcanoes in north Xinjiang, NW China, including 32 volcanoes on the edge of the Junggar <span class="hlt">basin</span>. These volcanoes are clustered and can be divided into calderas, volcanic domes, and volcanic necks. There are also 85 volcanoes inside the Junggar <span class="hlt">basin</span>, which are dominantly distributed in the Ke-Bai fractured zone of the northwestern margin of Junggar <span class="hlt">Basin</span>, 4 depressions (Dongdaohaizi Depression, Dishuiquan Depression, Sannan Depression and Wucaiwan Depression) and 7 uplifts (Baijiahai uplift, Beisantai uplift, Dibei uplift, Dinan uplift, Sangequan uplift, Shixi uplift and Xiayan uplift). The volcanoes inside the <span class="hlt">basin</span> are principally controlled by Hercynian Fault Systems, along NE and nearly EW trending faults and most developed in the interjunctions of the faults. The long modification by late-stage weathering and leaching made the volcanoes difficult to identify. Remaining volcanic landforms, changing trends of the volcanic lithofacies and the typical volcanic rock, such as the crypto- explosive breccia, are the typical marks of the late Paleozoic volcanoes in the field; and the concealed volcanic edifices are identified by the techniques of seismic identification, such as seismic slicing, analysis of the attribute and tectonic trend plane. The ages of the volcanic rocks are focused on from 340 Ma to 320Ma and from 300 Ma to 295 Ma, corresponding to the subducting periods of West Junggar and East Junggar. From early Carboniferous to late Carboniferous, the volcanic activities in Junggar <span class="hlt">Basin</span> and its <span class="hlt">adjacent</span> areas show a variation trend from undersea to continental, from deep water to shallow water and from continental margin to intracontinental.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JGRF..113.2010F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JGRF..113.2010F"><span>Mechanisms of basal ice formation in polar <span class="hlt">glaciers</span>: An evaluation of the apron entrainment model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fitzsimons, Sean; Webb, Nicola; Mager, Sarah; MacDonell, Shelley; Lorrain, Regi; Samyn, Denis</p> <p>2008-06-01</p> <p>Previous studies of polar <span class="hlt">glaciers</span> have argued that basal ice can form when these <span class="hlt">glaciers</span> override and entrain ice marginal aprons that accumulate <span class="hlt">adjacent</span> to steep ice cliffs. To test this idea, we have studied the morphology, structure, composition, and deformation of the apron and basal ice at the terminus of Victoria Upper <span class="hlt">Glacier</span> in the McMurdo dry valleys, which are located on the western coast of the Ross Sea at 77°S in southern Victoria Land, Antarctica. Our results show that the apron has two structural elements: an inner element that consists of strongly foliated ice that has a steep up-<span class="hlt">glacier</span> dip, and an outer element that lacks a consistent foliation and has a down-<span class="hlt">glacier</span>, slope-parallel dip. Although strain measurements show that the entire apron is deforming, the inner element is characterized by high strain rates, whereas relatively low rates of strain characterize the outer part of the apron. Co-isotopic analyses of the ice, together with analysis of solute chemistry and sedimentary characteristics, show that the apron is compositionally different from the basal ice. Our observations show that aprons may become deformed and partially entrained by advancing <span class="hlt">glaciers</span>. However, such an ice marginal process does not provide a satisfactory explanation for the origin of basal ice observed at the ice margin. Our interpretation of the origin of basal ice is that it is formed by subglacial processes, which are likely to include deformation and entrainment of subglacial permafrost.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/pp/1180/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/pp/1180/report.pdf"><span>Grinnell and Sperry <span class="hlt">Glaciers</span>, <span class="hlt">Glacier</span> National Park, Montana: A record of vanishing ice</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Johnson, Arthur</p> <p>1980-01-01</p> <p>Grinnell and Sperry <span class="hlt">Glaciers</span>, in <span class="hlt">Glacier</span> National Park, Mont., have both shrunk considerably since their discovery in 1887 and 1895, respectively. This shrinkage, a reflection of climatic conditions, is evident when photographs taken at the time of discovery are compared with later photographs. Annual precipitation and terminus-recession measurements, together with detailed systematic topographic mapping since 1900, clearly record the changes in the character and size of these <span class="hlt">glaciers</span>. Grinnell <span class="hlt">Glacier</span> decreased in area from 530 acres in 1900 to 315 acres in 1960 and to 298 acres in 1966. Between 1937 and 1969 the terminus receded nearly 1,200 feet. Periodic profile measurements indicate that in 1969 the surface over the main part of the <span class="hlt">glacier</span> was 25-30 feet lower than in 1950. Observations from 1947 to 1969 indicate annual northeastward movement ranging from 32 to 52 feet and generally averaging 35-45 feet. The annual runoff at the <span class="hlt">glacier</span> is estimated to be 150 inches, of which approximately 6 inches represents reduction in <span class="hlt">glacier</span> volume. The average annual runoff at a gaging station on Grinnell Creek 1.5 miles downvalley from the <span class="hlt">glacier</span> for the 20-year period, 1949-69, was 100 inches. The average annual precipitation over the <span class="hlt">glacier</span> was probably 120-150 inches. Sperry <span class="hlt">Glacier</span> occupied 800 acres in 1901; by 1960 it covered only 287 acres, much of its upper part having disappeared from the enclosing cirque. From 1938 to 1969 certain segments of the terminus receded more than 1,000 feet. Profile measurements dating from 1949 indicate a lowering of the <span class="hlt">glacier</span> surface below an altitude of 7,500 feet, but a fairly constant or slightly increased elevation of the surface above an altitude of 7,500 feet. Along one segment of the 1969 terminus the ice had been more than 100 feet thick in 1950. According to observations during 1949-69, average annual downslope movement was less than 15 feet per year in the central part of the <span class="hlt">glacier</span> and slightly more rapid toward</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.6720G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.6720G"><span>Sediment connectivity evolution on an alpine catchment undergoing <span class="hlt">glacier</span> retreat</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goldin, Beatrice; Rudaz, Benjamin; Bardou, Eric</p> <p>2014-05-01</p> <p>Climate changes can result in a wide range of variations of natural environment including retreating <span class="hlt">glaciers</span>. Melting from <span class="hlt">glaciers</span> will have a significant impact on the sediment transport characteristics of <span class="hlt">glacierized</span> alpine catchments that can affect downstream channel network. Sediment connectivity assessment, i.e. the degree of connections that controls sediment fluxes between different segments of a landscape, can be useful in order to address management activity on sediment fluxes changes of alpine streams. Through the spatial characterization of the connectivity patterns of a catchment and its potential evolution it is possible to both define sediment transport pathways and estimate different contributions of the sub-catchment as sediment sources. In this study, a topography based index (Cavalli et al., 2013) has been applied to assess spatial sediment connectivity in the Navisence catchment (35 km2), an alpine <span class="hlt">basin</span> located in the southern Walliser Alps (Switzerland) characterized by a complex <span class="hlt">glacier</span> system with well-developed lateral moraines on <span class="hlt">glacier</span> margins already crossed by several lateral channels. <span class="hlt">Glacier</span> retreat of the main glacial edifice will provide a new connectivity pattern. At present the <span class="hlt">glacier</span> disconnects lateral slopes from the main talweg: it is expected that its retreat will experience an increased connectivity. In order to study this evolution, two high resolution (2 m) digital terrain models (DTMs) describing respectively the terrain before and after <span class="hlt">glacier</span> retreat have been analyzed. The current DTM was obtained from high resolution photogrammetry (2 m resolution). The future DTM was derived from application of the sloping local base level (SLBL) routine (Jaboyedoff et al., 2004) on the current <span class="hlt">glacier</span> system, allowing to remove the ice body by reconstituting a U-shaped polynomial bedrock surface. From this new surface a coherent river network was drawn and slight random noise was added. Finally the river network was burned into</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.3742M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.3742M"><span>Subglacial bedrock topography of an active mountain <span class="hlt">glacier</span> in a high Alpine setting - insights from high resolution 3D cosmic-muon radiography of the Eiger <span class="hlt">glacier</span> (Bern, Central Alps, Switzerland)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mair, David; Lechmann, Alessandro; Nishiyama, Ryuichi; Schlunegger, Fritz; Ariga, Akitaka; Ariga, Tomoko; Scampoli, Paola; Vladymyrov, Mykhailo; Ereditato, Antonio</p> <p>2016-04-01</p> <p> step of our research will be identifying the morphometry of the bedrock beneath the <span class="hlt">glacier</span> (e.g., slope angles, curvatures and changes thereof, width to depth ratios and roughness) based on the muon radiography. We will combine these data with information about the fabric of the bedrock to determine how the bedrock properties have conditioned the erosional processes in this steep glacial cirque. References: Cook, S.J., & Swift, D.A., 2012. Subglacial <span class="hlt">basins</span>: Their origin and importance in glacial systems and landscapes. Earth-Science Reviews 115, 332-372.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMGC21G..01T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMGC21G..01T"><span>Climatic Teleconnections Recorded By Tropical Mountain <span class="hlt">Glaciers</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thompson, L. G.; Permana, D.; Mosley-Thompson, E.; Davis, M. E.</p> <p>2014-12-01</p> <p>Information from ice cores from the world's highest mountains in the Tropics demonstrates both local climate variability and a high degree of teleconnectivity across the Pacific <span class="hlt">basin</span>. Here we examine recently recovered ice core records from <span class="hlt">glaciers</span> near Puncak Jaya in Papua, Indonesia, which lie on the highest peak between the Himalayas and the South American Andes. These <span class="hlt">glaciers</span> are located on the western side of the Tropical Pacific warm pool, which is the "center of action" for interannual climate variability dominated by El Niño-Southern Oscillation (ENSO). ENSO either directly or indirectly affects most regions of Earth and their populations. In 2010, two ice cores measuring 32.13 m and 31.25 m were recovered to bedrock from the East Northwall Firn ice field. Both have been analyzed in high resolution (~3 cm sample length, 1156 and 1606 samples, respectively) for stable isotopes, dust, major ions and tritium concentrations. To better understand the controls on the oxygen isotopic (δ18 O) signal for this region, daily rainfall samples were collected between January 2013 and February 2014 at five weather stations over a distance of ~90 km ranging from 9 meters above sea level (masl) on the southern coast up to 3945 masl. The calculated isotopic lapse rate for this region is 0.24 ‰/100m. Papua, Indonesian ice core records are compared to ice core records from Dasuopu <span class="hlt">Glacier</span> in the central Himalayas and from Quelccaya, Huascarán, Hualcán and Coropuna ice fields in the tropical Andes of Peru on the eastern side of the Pacific Ocean. The composite of the annual isotopic time series from these cores is significantly (R2 =0.53) related to tropical Pacific sea surface temperatures (SSTs), reflecting the strong linkage between tropical Pacific SSTs associated with ENSO and tropospheric temperatures in the low latitudes. New data on the already well-documented concomitant loss of ice on Quelccaya, Kilimanjaro in eastern Africa and the ice fields near Puncak</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26638969','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26638969"><span>Release of PCBs from Silvretta <span class="hlt">glacier</span> (Switzerland) investigated in lake sediments and meltwater.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pavlova, P A; Zennegg, M; Anselmetti, F S; Schmid, P; Bogdal, C; Steinlin, C; Jäggi, M; Schwikowski, M</p> <p>2016-06-01</p> <p>This study is part of our investigations about the release of persistent organic pollutants from melting Alpine <span class="hlt">glaciers</span> and the relevance of the <span class="hlt">glaciers</span> as secondary sources of legacy pollutants. Here, we studied the melt-related release of polychlorinated biphenyls (PCBs) in proglacial lakes and <span class="hlt">glacier</span> streams of the catchment of the Silvretta <span class="hlt">glacier</span>, located in the Swiss Alps. To explore a spatial and temporal distribution of chemicals in <span class="hlt">glacier</span> melt, we combined two approaches: (1) analysing a sediment record as an archive of past remobilization and (2) passive water sampling to capture the current release of PCBs during melt period. In addition, we determined PCBs in a <span class="hlt">non-glacier</span>-fed stream as a reference for the background pollutant level in the area. The PCBs in the sediment core from the Silvretta lake generally complied with trends of PCB emissions into the environment. Elevated concentrations during the most recent ten years, comparable in level with times of the highest atmospheric input, were attributed to accelerated melting of the <span class="hlt">glacier</span>. This interpretation is supported by the detected PCB fractionation pattern towards heavier, less volatile congeners, and by increased activity concentrations of the radioactive tracer (137)Cs in this part of the sediment core. In contrast, PCB concentrations were not elevated in the stream water, since no significant difference between pollutant concentrations in the <span class="hlt">glacier</span>-fed and the <span class="hlt">non-glacier</span>-fed streams was detected. In stream water, no current decrease of the PCBs with distance from the <span class="hlt">glacier</span> was observed. Thus, according to our data, an influence of PCBs release due to accelerated <span class="hlt">glacier</span> melt was only detected in the proglacial lake, but not in the other compartments of the Silvretta catchment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.9675C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.9675C"><span>Analysis of snow-glacial historical and projected flows in Olivares river <span class="hlt">basin</span>. Comparison between DHSVM and WEAP models.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cepeda, Javier; Vargas, Ximena</p> <p>2017-04-01</p> <p>In the Andes Mountains, in central Chile, <span class="hlt">glaciers</span> are a key element to both environment and economy, since they contribute highly to streamflow during the summer season. Many studies have been performed in order to understand the actual contribution of glacial-based streamflow and the expected response of <span class="hlt">glaciers</span> to climatological alterations such as climate change. This work studies and analyses the historical and future streamflow on the Olivares river <span class="hlt">basin</span>, located close to Chile's capital city, Santiago, under climatic change scenario RCP8.5. For this, we use two hydrological models with different topology, to have more consistency in the results, and analysing the differences because of the conceptualization of the processes and its spatial scale. DHSVM is a distributed, physically based model, while WEAP is a semi-distributed model that represents some processes conceptually and others physically based. Both models are calibrated considering streamflow and snow cover data from the period 2001-2012 at a daily scale. Additionally, comparisons between the modelled <span class="hlt">glacier</span> area variations and LANDSAT images are performed to strengthen the calibration process. Climate change projections are obtained from five Global Circulation Models (GCM) under RCP8.5 scenario. Changes in <span class="hlt">glacier</span> area, volume and glacial streamflow contribution to <span class="hlt">basin</span> discharge are analysed, comparing two future time lapses, near-future period (2015-2044) and far-future (2045-2074), to a baseline period (1985-2004). The <span class="hlt">basin</span> has an area of 543 km2, with elevations ranging from 1,528 to 6,024 m.a.s.l. and an important <span class="hlt">glacier</span> presence. According to the National <span class="hlt">Glacier</span> Cadastre developed by Chile Water Authority (DGA) in 2012, there are 80 uncovered <span class="hlt">glaciers</span> within the <span class="hlt">basin</span>, the most important being Juncal Sur, Olivares Alfa, Beta and Gamma. <span class="hlt">Glacier</span> area represented 17% of the <span class="hlt">basin</span> in 1985, while they made up only to 11% in 2015.The <span class="hlt">glaciers</span> are located at altitudes ranging from 3,500 to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70020512','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70020512"><span>Climate variations and changes in mass of three <span class="hlt">glaciers</span> in western North America</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hodge, S.M.; Trabant, D.C.; Krimmel, R.M.; Heinrichs, T.A.; March, R.S.; Josberger, E.G.</p> <p>1998-01-01</p> <p>Time series of net and seasonal mass balances for three <span class="hlt">glaciers</span> in western North America, one in the Pacific Northwest and two in Alaska, show various relationships to Pacific hemisphere climate indexes. During the winter season the two coastal, maritime-regime <span class="hlt">glaciers</span>, over 2000 km apart, are affected almost identically, albeit inversely, by atmospheric and oceanic conditions in both the tropical and North Pacific. The two Alaska <span class="hlt">glaciers</span>, only 350 km apart, have almost no coherence. Lag correlations show that in winter the maritime <span class="hlt">glaciers</span> are influenced by concurrent conditions in the North Pacific, but by conditions in the tropical Pacific in August-September of the prior northern summer. The winter balance variations contain interannual El Nino-Southern Oscillation variability superimposed on North Pacific interdecadal variability; the interdecadal 1976-77 climate regime shift is clearly evident. The summer balances and the continental-regime <span class="hlt">glacier</span> have a general lack of correlations, with no clear, strong, consistent patterns, probably a result of being influenced more by local processes or by circulation patterns outside the Pacific Ocean <span class="hlt">basin</span>. The results show the Pacific Northwest is strongly influenced by conditions in the tropical Pacific, but that this teleconnection has broken down in recent years, starting in 1989. During the seven years since then (1989-95), all three <span class="hlt">glaciers</span> have shown, for the first time, coherent signals, which were net mass loss at the highest rate in the entire record. The authors' results agree with those of other recent studies that suggest these recent years are unusual and may be a signature of climate warming.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1816954K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1816954K"><span>Hydrological modelling improvements required in <span class="hlt">basins</span> in the Hindukush-Karakoram-Himalayas region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khan, Asif; Richards, Keith S.; McRobie, Allan; Booij, Martijn</p> <p>2016-04-01</p> <p>Millions of people rely on river water originating from <span class="hlt">basins</span> in the Hindukush-Karakoram-Himalayas (HKH), where snow- and ice-melt are significant flow components. One such <span class="hlt">basin</span> is the Upper Indus <span class="hlt">Basin</span> (UIB), where snow- and ice-melt can contribute more than 80% of total flow. Containing some of the world's largest alpine <span class="hlt">glaciers</span>, this <span class="hlt">basin</span> may be highly susceptible to global warming and climate change, and reliable predictions of future water availability are vital for resource planning for downstream food and energy needs in a changing climate, but depend on significantly improved hydrological modelling. However, a critical assessment of available hydro-climatic data and hydrological modelling in the HKH region has identified five major failings in many published hydro-climatic studies, even those appearing in reputable international journals. The main weaknesses of these studies are: i) incorrect <span class="hlt">basin</span> areas; ii) under-estimated precipitation; iii) incorrectly-defined <span class="hlt">glacier</span> boundaries; iv) under-estimated snow-cover data; and v) use of biased melt factors for snow and ice during the summer months. This paper illustrates these limitations, which have either resulted in modelled flows being under-estimates of measured flows, leading to an implied severe water scarcity; or have led to the use of unrealistically high degree-day factors and over-estimates of <span class="hlt">glacier</span> melt contributions, implying unrealistic melt rates. These effects vary amongst sub-<span class="hlt">basins</span>. Forecasts obtained from these models cannot be used reliably in policy making or water resource development, and need revision. Detailed critical analysis and improvement of existing hydrological modelling may be equally necessary in other mountain regions across the world.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA03386&hterms=Glacier+retreat+global&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DGlacier%2Bretreat%2Bglobal','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA03386&hterms=Glacier+retreat+global&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DGlacier%2Bretreat%2Bglobal"><span>Malaspina <span class="hlt">Glacier</span>, Alaska, Perspective with Landsat Overlay</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2003-01-01</p> <p><p/>Malaspina <span class="hlt">Glacier</span> in southeastern Alaska is considered the classic example of a piedmont <span class="hlt">glacier</span>. Piedmont <span class="hlt">glaciers</span> occur where valley <span class="hlt">glaciers</span> exit a mountain range onto broad lowlands, are no longer laterally confined, and spread to become wide lobes. Malaspina <span class="hlt">Glacier</span> is actually a compound <span class="hlt">glacier</span>, formed by the merger of several valley <span class="hlt">glaciers</span>, the most prominent of which seen here are Agassiz <span class="hlt">Glacier</span> (left) and Seward <span class="hlt">Glacier</span> (right). In total, Malaspina <span class="hlt">Glacier</span> is up to 65 kilometers (40 miles) wide and extends up to 45 kilometers (28 miles) from the mountain front nearly to the sea. <p/>This perspective view was created from a Landsat satellite image and an elevation model generated by the Shuttle Radar Topography Mission (SRTM). Landsat views both visible and infrared light, which have been combined here into a color composite that generally shows glacial ice in light blue, snow in white, vegetation in green, bare rock in grays and tans, and the ocean (foreground) in dark blue. The back (northern) edge of the data set forms a false horizon that meets a false sky. <p/><span class="hlt">Glaciers</span> erode rocks, carry them down slope, and deposit them at the edge of the melting ice, typically in elongated piles called moraines. The moraine patterns at Malaspina <span class="hlt">Glacier</span> are quite spectacular in that they have huge contortions that result from the <span class="hlt">glacier</span> crinkling as it gets pushed from behind by the faster-moving valley <span class="hlt">glaciers</span>. <p/><span class="hlt">Glaciers</span> are sensitive indicators of climatic change. They can grow and thicken with increasing snowfall and/or decreased melting. Conversely, they can retreat and thin if snowfall decreases and/or atmospheric temperatures rise and cause increased melting. Landsat imaging has been an excellent tool for mapping the changing geographic extent of <span class="hlt">glaciers</span> since 1972. The elevation measurements taken by SRTM in February 2000 now provide a near-global baseline against which future <span class="hlt">non</span>-polar region glacial thinning or thickening can be assessed. <p</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1918157F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1918157F"><span>Geological controls on bedrock topography and ice sheet dynamics in the Wilkes Subglacial <span class="hlt">Basin</span> sector of East Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferraccioli, Fausto; Armadillo, Egidio; Young, Duncan; Blankenship, Donald; Jordan, Tom; Siegert, Martin</p> <p>2017-04-01</p> <p>The Wilkes Subglacial <span class="hlt">Basin</span> extends for 1,400 km into the interior of East Antarctica and hosts several major <span class="hlt">glaciers</span> that drain a large sector of the East Antarctic Ice Sheet. The deep northern Wilkes Subglacial <span class="hlt">Basin</span> underlies the catchments of the Matusevich, Cook, Ninnis and Mertz <span class="hlt">Glaciers</span>, which are largely marine-based and hence potentially particularly sensitive to past and also predicted future ocean and climate warming. Sediment provenance studies suggest that the <span class="hlt">glaciers</span> flowing in this region may have retreated significantly compared to their modern configuration, as recently as the warm mid-Pliocene interval, potentially contributing several m to global sea level rise (Cook et al.,Nature Geosci., 2013). Here we combine airborne radar, aeromagnetic and airborne gravity observations collected during the international WISE-ISODYN and ICECAP aerogeophysical campaigns with vintage datasets to help unveil subglacial geology and deeper crustal architecture and to assess its influence on bedrock topography and ice sheet dynamics in the northern Wilkes Subglacial <span class="hlt">Basin</span>. Aeromagnetic images reveal that the Matusevich <span class="hlt">Glacier</span> is underlain by a ca 480 Ma thrust fault system (the Exiles Thrust), which has also been inferred to have been reactivated in response to intraplate Cenozoic strike-slip faulting. Further to the west, the linear Eastern <span class="hlt">Basins</span> are controlled by the Prince Albert Fault System. The fault system continues to the south, where it provides structural controls for both the Priestley and Reeves <span class="hlt">Glaciers</span>. The inland Central <span class="hlt">Basins</span> continue in the coastal area underlying the fast flowing Cook ice streams, implying that potential ocean-induced changes could propagate further into the interior of the ice sheet. We propose based on an analogy with the Rennick Graben that these deep subglacial <span class="hlt">basins</span> are controlled by the underlying horst and graben crustal architecture. Given the interpreted subglacial distribution of Beacon sediments and Ferrar</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.C41C0676G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.C41C0676G"><span>A Comparison of the Seasonal Change of Albedo across <span class="hlt">Glaciers</span> and Ice-Covered Lakes of the Taylor Valley, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gooseff, M. N.; Bergstrom, A.</p> <p>2016-12-01</p> <p>The Dry Valleys of Antarctica are a polar desert ecosystem consisting of piedmont and alpine <span class="hlt">glaciers</span>, ice-covered lakes, and vast expanses of bare soil. The ecosystem is highly dependent on glacial melt a water source. Because average summer temperatures are close to freezing, <span class="hlt">glacier</span> ice and lake ice are very closely linked to the energy balance. A slight increase in incoming radiation or decrease in albedo can have large effects on the timing and volume of available liquid water. However, we have yet to fully characterize the seasonal evolution of albedo in the valleys. In this study, we used a camera, gps, and short wave radiometer to characterize the albedo within and across landscape types in the Taylor Valley. These instruments were attached to a helicopter and flown on a prescribed path along the valley at approximately 300 feet above the ground surface five different times throughout the season from mid-November to mid-January, 2015-2016. We used these data to calculate the albedo of each <span class="hlt">glacier</span>, lake, and the soil surface of the lake <span class="hlt">basins</span> in the valley for each flight. As expected, we found that all landscape types had significantly different albedo, with the <span class="hlt">glaciers</span> consistently the highest throughout the season and the bare soils the lowest (p-value < 0.05). We hypothesized that albedo would decrease throughout the season with snow melt and increasing sediment exposure on the <span class="hlt">glacier</span> and lake surfaces. However, small snow events (< 3 cm) caused somewhat persistent high albedo on the lakes and <span class="hlt">glaciers</span>. Furthermore, there was a range in albedo across <span class="hlt">glaciers</span> and each responded to seasonal snow and melt differently. These findings highlight the importance of understanding the spatial and temporal variability in albedo and the close coupling of climate and landscape response. We can use this new understanding of landscape albedo to better predict how the Dry Valley ecosystems will respond to changing climate at the <span class="hlt">basin</span> scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70015971','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70015971"><span>Hydrogeochemistry and stable isotopes of ground and surface waters from two <span class="hlt">adjacent</span> closed <span class="hlt">basins</span>, Atacama Desert, northern Chile</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Alpers, Charles N.; Whittemore, Donald O.</p> <p>1990-01-01</p> <p>The geochemistry and stable isotopes of groundwaters, surface waters, and precipitation indicate different sources of some dissolved constituents, but a common source of recharge and other constituents in two <span class="hlt">adjacent</span> closed <span class="hlt">basins</span> in the Atacama Desert region of northern Chile (24??15???-24??45???S). Waters from artesian wells, trenches, and ephemeral streams in the Punta Negra <span class="hlt">Basin</span> are characterized by concentrations of Na>Ca>Mg and Cl ???SO4, with TDS Mg ??? Ca and SO4 > Cl, with TDS also Mg ??? Ca and SO4 > Cl, but with TDS up to 40 g/l. The deep mine waters have pH between 3.2 and 3.9, and are high in dissolved CO2 (??13 C = -4.8%PDB), indicating probable interaction with oxidizing sulfides. The deep mine waters have ??18O values of ???-1.8%.compared with values < -3.5??? for other Hamburgo <span class="hlt">Basin</span> waters; thus the mine waters may represent a mixture of meteoric waters with deeper "metamorphic" waters, which had interacted with rocks and exchanged oxygen isotopes at elevated temperatures. Alternatively, the deep mine waters may represent fossil meteoric waters which evolved isotopically along an evaporative trend starting from values quite depleted in ??18O and ??Dd relative to either precipitation or shallow groundwaters. High I/Br ratios in the Hamburgo <span class="hlt">Basin</span> waters and La Escondida mine waters are consistent with regionally high I in surficial deposits in the Atacama Desert region and may represent dissolution of a wind-blown evaporite component. Rain and snow collected during June 1984, indicate systematic ??18O and ??D fractionation with increasing elevation between 3150 and 4180 m a.s.l. (-0.21??.??18O and -1.7??.??D per 100 m). Excluding the deep mine waters from La Escondida, the waters from the Hamburgo and Punta Negra <span class="hlt">Basins</span> have similar ??D and ??18O values and together show a distinct evaporative trend (??D = 5.0 ??18O - 20.2). Snowmelt from the central Andes Cordillera to the east is the most likely source of recharge to both <span class="hlt">basins</span>. Some of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JGRD..113.5103R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JGRD..113.5103R"><span>Predicting the response of seven Asian <span class="hlt">glaciers</span> to future climate scenarios using a simple linear <span class="hlt">glacier</span> model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ren, Diandong; Karoly, David J.</p> <p>2008-03-01</p> <p>Observations from seven Central Asian <span class="hlt">glaciers</span> (35-55°N; 70-95°E) are used, together with regional temperature data, to infer uncertain parameters for a simple linear model of the <span class="hlt">glacier</span> length variations. The <span class="hlt">glacier</span> model is based on first order <span class="hlt">glacier</span> dynamics and requires the knowledge of reference states of forcing and <span class="hlt">glacier</span> perturbation magnitude. An adjoint-based variational method is used to optimally determine the <span class="hlt">glacier</span> reference states in 1900 and the uncertain <span class="hlt">glacier</span> model parameters. The simple <span class="hlt">glacier</span> model is then used to estimate the <span class="hlt">glacier</span> length variations until 2060 using regional temperature projections from an ensemble of climate model simulations for a future climate change scenario (SRES A2). For the period 2000-2060, all <span class="hlt">glaciers</span> are projected to experience substantial further shrinkage, especially those with gentle slopes (e.g., <span class="hlt">Glacier</span> Chogo Lungma retreats ˜4 km). Although nearly one-third of the year 2000 length will be reduced for some small <span class="hlt">glaciers</span>, the existence of the <span class="hlt">glaciers</span> studied here is not threatened by year 2060. The differences between the individual <span class="hlt">glacier</span> responses are large. No straightforward relationship is found between <span class="hlt">glacier</span> size and the projected fractional change of its length.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120003719','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120003719"><span>What do We Know the Snow Darkening Effect Over Himalayan <span class="hlt">Glaciers</span>?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yasunari, T. J.; Lau, K.-U.; Koster, R. D.; Suarez, M.; Mahanama, S. P.; Gautam, R.; Kim, K. M.; Dasilva, A. M.; Colarco, P. R.</p> <p>2011-01-01</p> <p>The atmospheric absorbing aerosols such as dust, black carbon (BC), organic carbon (OC) are now well known warming factors in the atmosphere. However, when these aerosols deposit onto the snow surface, it causes darkening of snow and thereby absorbing more energy at the snow surface leading to the accelerated melting of snow. If this happens over Himalayan <span class="hlt">glacier</span> surface, the <span class="hlt">glacier</span> meltings are expected and may contribute the mass balance changes though the mass balance itself is more complicated issue. <span class="hlt">Glacier</span> has mainly two parts: ablation and accumulation zones. Those are separated by the Equilibrium Line Altitude (ELA). Above and below ELA, snow accumulation and melting are dominant, respectively. The change of ELA will influence the <span class="hlt">glacier</span> disappearance in future. In the Himalayan region, many <span class="hlt">glacier</span> are debris covered <span class="hlt">glacier</span> at the terminus (i.e., in the ablation zone). Debris is pieces of rock from local land and the debris covered parts are probably not affected by any deposition of the absorbing aerosols because the snow surface is already covered by debris (the debris covered parts have different mechanism of melting). Hence, the contribution of the snow darkening effect is considered to be most important "over <span class="hlt">non</span> debris covered part" of the Himalayan <span class="hlt">glacier</span> (i.e., over the snow or ice surface area). To discuss the whole <span class="hlt">glacier</span> retreat, mass balance of each <span class="hlt">glacier</span> is most important including the discussion on <span class="hlt">glacier</span> flow, vertical compaction of <span class="hlt">glacier</span>, melting amount, etc. The contribution of the snow darkening is mostly associated with "the snow/ice surface melting". Note that the surface melting itself is not always directly related to <span class="hlt">glacier</span> retreats because sometimes melt water refreezes inside of the <span class="hlt">glacier</span>. We should discuss <span class="hlt">glacier</span> retreats in terms of not only the snow darkening but also other contributions to the mass balance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18...73R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18...73R"><span>Debris-covered Himalayan <span class="hlt">glaciers</span> under a changing climate: observations and modelling of Khumbu <span class="hlt">Glacier</span>, Nepal</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rowan, Ann; Quincey, Duncan; Egholm, David; Gibson, Morgan; Irvine-Fynn, Tristram; Porter, Philip; Glasser, Neil</p> <p>2016-04-01</p> <p>Many mountain <span class="hlt">glaciers</span> are characterised in their lower reaches by thick layers of rock debris that insulate the <span class="hlt">glacier</span> surface from solar radiation and atmospheric warming. Supraglacial debris modifies the response of these <span class="hlt">glaciers</span> to climate change compared to <span class="hlt">glaciers</span> with clean-ice surfaces. However, existing modelling approaches to predicting variations in the extent and mass balance of debris-covered <span class="hlt">glaciers</span> have relied on numerical models that represent the processes governing <span class="hlt">glaciers</span> with clean-ice surfaces, and yield conflicting results. Moreover, few data exist describing the mass balance of debris-covered <span class="hlt">glaciers</span> and many observations are only made over short periods of time, but these data are needed to constrain and validate numerical modelling experiments. To investigate the impact of supraglacial debris on the response of a <span class="hlt">glacier</span> to climate change, we developed a numerical model that couples the flow of ice and debris to include important feedbacks between mass balance, ice flow and debris accumulation. We applied this model to a large debris-covered Himalayan <span class="hlt">glacier</span> - Khumbu <span class="hlt">Glacier</span> in the Everest region of Nepal. Our results demonstrate that supraglacial debris prolongs the response of the <span class="hlt">glacier</span> to warming air temperatures and causes lowering of the <span class="hlt">glacier</span> surface in situ, concealing the magnitude of mass loss when compared with estimates based on glacierised area. Since the Little Ice Age, the volume of Khumbu <span class="hlt">Glacier</span> has reduced by 34%, while <span class="hlt">glacier</span> area has reduced by only 6%. We predict a further decrease in <span class="hlt">glacier</span> volume of 8-10% by AD2100 accompanied by dynamic and physical detachment of the debris-covered tongue from the active <span class="hlt">glacier</span> within the next 150 years. For five months during the 2014 summer monsoon, we measured temperature profiles through supraglacial debris and proglacial discharge on Khumbu <span class="hlt">Glacier</span>. We found that temperatures at the ice surface beneath 0.4-0.7 m of debris were sufficient to promote considerable</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001938.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001938.html"><span>Matusevich <span class="hlt">Glacier</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-08</p> <p>NASA image acquired September 6, 2010 The Matusevich <span class="hlt">Glacier</span> flows toward the coast of East Antarctica, pushing through a channel between the Lazarev Mountains and the northwestern tip of the Wilson Hills. Constrained by surrounding rocks, the river of ice holds together. But stresses resulting from the glacier’s movement make deep crevasses, or cracks, in the ice. After passing through the channel, the <span class="hlt">glacier</span> has room to spread out as it floats on the ocean. The expanded area and the jostling of ocean waves prompts the ice to break apart, which it often does along existing crevasses. On September 6, 2010, the Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite captured this natural-color image of the margin of Matusevich <span class="hlt">Glacier</span>. Shown here just past the rock-lined channel, the <span class="hlt">glacier</span> is calving large icebergs. Low-angled sunlight illuminates north-facing surfaces and casts long shadows to the south. Fast ice anchored to the shore surrounds both the <span class="hlt">glacier</span> tongue and the icebergs it has calved. Compared to the <span class="hlt">glacier</span> and icebergs, the fast ice is thinner with a smoother surface. Out to sea (image left), the sea ice is even thinner and moves with winds and currents. Matusevich <span class="hlt">Glacier</span> does not drain a significant amount of ice off of the Antarctic continent, so the glacier’s advances and retreats lack global significance. Like other Antarctic <span class="hlt">glaciers</span>, however, Matusevich helps glaciologists form a larger picture of Antarctica’s glacial health and ice sheet volume. NASA Earth Observatory image created by Jesse Allen and Robert Simmon, using EO-1 ALI data provided courtesy of the NASA EO-1 team. Caption by Michon Scott based on image interpretation by Robert Bindschadler, NASA Goddard Space Flight Center, and Walt Meier, National Snow and Ice Data Center. Instrument: EO-1 - ALI Credit: NASA Earth Observatory NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70184991','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70184991"><span>Observations and modeling of fjord sedimentation during the 30 year retreat of Columbia <span class="hlt">Glacier</span>, AK</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Love, Katherine B; Hallet, Bernard; Pratt, Thomas L.; O'Neel, Shad</p> <p>2016-01-01</p> <p>To explore links between <span class="hlt">glacier</span> dynamics, sediment yields and the accumulation of glacial sediments in a temperate setting, we use extensive glaciological observations for Columbia <span class="hlt">Glacier</span>, Alaska, and new oceanographic data from the fjord exposed during its retreat. High-resolution seismic data indicate that 3.2 × 108 m3 of sediment has accumulated in Columbia Fjord over the past three decades, which corresponds to ~5 mm a−1 of erosion averaged over the glaciated area. We develop a general model to infer the sediment-flux history from the <span class="hlt">glacier</span> that is compatible with the observed retreat history, and the thickness and architecture of the fjord sediment deposits. Results reveal a fivefold increase in sediment flux from 1997 to 2000, which is not correlated with concurrent changes in ice flux or retreat rate. We suggest the flux increase resulted from an increase in the sediment transport capacity of the subglacial hydraulic system due to the retreat-related steepening of the <span class="hlt">glacier</span> surface over a known subglacial deep <span class="hlt">basin</span>. Because variations in subglacial sediment storage can impact glacial sediment flux, in addition to changes in climate, erosion rate and <span class="hlt">glacier</span> dynamics, the interpretation of climatic changes based on the sediment record is more complex than generally assumed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003GeoRL..30.1857M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003GeoRL..30.1857M"><span>Multi-decadal elevation changes on Bagley Ice Valley and Malaspina <span class="hlt">Glacier</span>, Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Muskett, Reginald R.; Lingle, Craig S.; Tangborn, Wendell V.; Rabus, Bernhard T.</p> <p>2003-08-01</p> <p>Digital elevation models (DEMs) of Bagley Ice Valley and Malaspina <span class="hlt">Glacier</span> produced by (i) Intermap Technologies, Inc. (ITI) from airborne interferometric synthetic aperture radar (InSAR) data acquired 4-13 September 2000, (ii) the German Aerospace Center (DRL) from spaceborne InSAR data acquired by the Shuttle Radar Topography Mission (SRTM) 11-22 February 2000, and (iii) the US Geological Survey (USGS) from aerial photographs acquired in 1972/73, were differenced to estimate <span class="hlt">glacier</span> surface elevation changes from 1972 to 2000. Spatially <span class="hlt">non</span>-uniform thickening, 10 +/- 7 m on average, is observed on Bagley Ice Valley (accumulation area) while <span class="hlt">non</span>-uniform thinning, 47 +/- 5 m on average, is observed on the <span class="hlt">glaciers</span> of the Malaspina complex (mostly ablation area). Even larger thinning is observed on the retreating tidewater Tyndall <span class="hlt">Glacier</span>. These changes have resulted from increased temperature and precipitation associated with climate warming, and rapid tidewater retreat.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.8476K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.8476K"><span>Will mountain regions dominated by small headwater <span class="hlt">glaciers</span> experience the same paraglacial response as large valley systems?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kirkbride, Martin P.; Deline, Philip</p> <p>2017-04-01</p> <p>Rapid 20th Century and early 21st Century retreat of cirque <span class="hlt">glaciers</span> in the western European Alp has revealed extensive forelands across and onto which a variety of thermal, slope and fluvial process operate. These effect a transition from a subglacial to a proglacial landsystem, by reworking sediment and reorganising drainage networks. The landsystem achieves a state of preservation once no more adjustment is possible due to buffering by channel network evolution, channel armouring, vegetation growth, and (rarely) sediment exhaustion. We find that no consistent trajectory of change across all sites. Rather, paraglacial responses in the cirque environment show differences from the classical valley-<span class="hlt">glacier</span> landscape response model, involving variable slope-channel coupling. Reasons for diverse and site-specific behaviour include inherited landforms of deglaciation (<span class="hlt">glacier</span> ice core survival and degradation), scale and gradient, and surface materials (bedrock, fine till, and/or blocky till). At some cirques, these are anticipated to restrict the downstream propagation of a paraglacial "signal" of diffusion of fluvial-transported sediment through the catchment. At others, such a signal may be propagated from the headwater <span class="hlt">basin</span>. However a high proportion of glacial material generally remains within the <span class="hlt">glacier</span> foreland, due to some combination of (1) formation of proglacial <span class="hlt">basin</span> sediment traps; (2) inefficiency of disorganised fluvial networks, (3) armouring of cirque floors by coarse melt-out-tills, and (4) locking of streams into rock-controlled channels. These effects appear to be more pronounce for the early 21st century paraglacial landsystems than they were for the post-"Little Ice Age" maximum landsystems of the late 19th Century at the same sites. The long-term preservation potential of most recent primary glacial deposits and within-cirque paraglacial landforms appears to be high. These landform assemblages represent the dramatic termination from the long</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1816447R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1816447R"><span>Using isotope, hydrochemical methods and energy-balance modelling to estimate contribution of different components to flow forming process in a high-altitude catchment (Dzhancuat river <span class="hlt">basin</span> case study)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rets, Ekaterina; Loshakova, Nadezhda; Chizhova, Julia; Kireeva, Maria; Frolova, Natalia; Tokarev, Igor; Budantseva, Nadine; Vasilchuk, Yurij</p> <p>2016-04-01</p> <p>A multicomponent structure of sources of river runoff formation is characteristic of high-altitude territories: ice and firn melting; seasonal snow melting on <span class="hlt">glacier</span> covered and <span class="hlt">non-glacier</span> area of a watershed; liquid precipitation; underground waters. In addition, each of these components can run off the watershed surface in different ways. Use of isotopic, hydrochemical methods and energy balance modelling provides possibility to estimate contribution of different components to river runoff that is an essential to understand the mechanism of flow formation in mountainious areas. A study was carried out for Dzhancuat river <span class="hlt">basin</span> that was chosen as representative for North Caucasus in course of the International Hydrological Decade. Complex glaciological, hydrological and meteorological observation have been carried in the <span class="hlt">basin</span> since 1965. In years 2013-2015 the program also included daily collecting of water samples on natural stable isotopes on the Dzhancuat river gauging station, and sampling water nourishment sources (ice, snow, firn, liquid precipitation) within the study area. More then 800 water samples were collected. Application of an energy balance model of snow and ice melt with distributed parameters provided an opportunity to identify Dzhancuat river runoff respond to <span class="hlt">glaciers</span> melt regime and seasonal redistribution of melt water. The diurnal amplitude of oscillation of the Dzhakuat river runoff in the days without precipitation is formed by melting at almost snow-free areas of the Dzhancuat <span class="hlt">glacier</span> tongues. Snowmelt water from the <span class="hlt">non-glacierized</span> part contributes to the formation of the next day runoff. A wave of snow and firn melt in upper zones of <span class="hlt">glacier</span> flattens considerably during filtration through snow and run-off over the surface and in the body of the <span class="hlt">glacier</span>. This determines a general significant inertia of the Dzhacuat river runoff. Some part of melt water is stored into natural regulating reservoirs of the watershed that supply the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMPP43A1219R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMPP43A1219R"><span>Do <span class="hlt">Glaciers</span> on Cascade Volcanoes Behave Differently Than Other <span class="hlt">Glaciers</span> in the Region?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Riedel, J. L.; Ryane, C.; Osborn, J.; Davis, T.; Menounos, B.; Clague, J. J.; Koch, J.; Scott, K. M.; Reasoner, M.</p> <p>2006-12-01</p> <p>It has been suggested that <span class="hlt">glaciers</span> on two stratovolcanoes in the Cascade Range of Washington state, Mt. Baker and <span class="hlt">Glacier</span> Peak, achieved their maximum extent of the past 10,000 years during the early Holocene. These findings differ from most evidence in western North America, which indicates that Little Ice Age moraines represent the most extensive <span class="hlt">glacier</span> advances of the Holocene. Significant early Holocene advances are difficult to reconcile with the documented warm, dry conditions at this time in western North America. Our data indicate that <span class="hlt">glaciers</span> on these volcanoes responded similarly to Holocene climatic events as <span class="hlt">glaciers</span> in other areas in Washington and British Columbia. Heavy winter accumulation and favorable hypsometry have been proposed as the explanations for the unusual behavior of <span class="hlt">glaciers</span> on volcanoes compared to similar-sized <span class="hlt">glaciers</span> elsewhere in the Cascade Range. However, <span class="hlt">glacier</span> mass balance on the volcanoes is controlled by not only these factors, but also by <span class="hlt">glacier</span> geometry, snow erosion and ablation. Accumulation zones of <span class="hlt">glaciers</span> on isolated Cascade stratovolcanoes are high, but are narrow at the top. For example, the accumulation zone of Deming <span class="hlt">Glacier</span> on the southwest side of Mt. Baker extends above 3000 m asl, but due to its wedge shape lies largely below 2500 m asl. Furthermore, <span class="hlt">glaciers</span> on Mt. Baker and other symmetrical volcanoes have high ablation rates because they are not shaded, and south-southwest aspects are subject to erosion of snow by prevailing southwesterly winds. Modern <span class="hlt">glacier</span> observations in the North Cascades quantify the important influence of aspect and snow erosion on <span class="hlt">glacier</span> mass balance. For example, average equilibrium line altitude (ELA) of Easton <span class="hlt">Glacier</span> on the south flank of Mt. Baker is 2160 m, whereas the ELA of a north-facing cirque <span class="hlt">glacier</span> 25km to the east is 2040m. Our research at Mt. Baker contradicts the claim of extensive early Holocene advances on the south flank of the volcano. Tephra set SC, which</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.C32A..08K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.C32A..08K"><span>Himalayan <span class="hlt">Glacier</span> Disasters: Changing Geomorphological Process Landscape, or a Changing Human Landscape?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kargel, J. S.; Leonard, G. J.</p> <p>2012-12-01</p> <p>Recent deadly <span class="hlt">glacier</span>-related disasters in the Himalayan-Karakoram region—the Attabad landslide and formation of <span class="hlt">glacier</span> meltwater-fed Lake Gojal, the Gayari ice avalanche/landslide and burial of a Pakistani Army base, and the Seti River outburst disaster—beg the question of whether disasters may be on the rise. Science is not yet ready to offer a full answer, but it is an important one to resolve, because future land-use planning and mitigative measures may be affected. Natural disasters have been commonplace throughout the long human history of the Himalaya-Karakoram region. The broad outlines of the changing natural process, natural hazard, and risk environment may be established. The risk is rising rapidly primarily due to increased human presence in these once-forbidding mountains. Risk is shifting also because climate change is modifying the land surface process system. Rapidly changing <span class="hlt">glaciers</span> cause a destabilization of the landscape. <span class="hlt">Glaciers</span> are fundamentally a mestastable phenomenon put in motion by the high gravitational potential energies of the components of glacial systems: snow, ice, water, and debris. Any change in the climate-land-<span class="hlt">glacier</span> system MUST result in a change in the land process system, with hazards and risks rising or falling or changing location or type. Most commonly, <span class="hlt">glacier</span>-related disasters include a natural process cascade; as the factors affecting land surface processes and the frequency or magnitude of any one of the elements of the process cascade changes, the net hazard and risk to people changes. Otherwise similar <span class="hlt">glaciers</span> and <span class="hlt">glacierized</span> <span class="hlt">basins</span> have differing sets of hazardous conditions and processes depending on whether the <span class="hlt">glacier</span> is stable, advancing or retreating. The consequences for the overall risk to people will depend on the details of a specific <span class="hlt">glacier</span> near a particular village or bridge or railroad. One size does not fit all. Generalizations about trends in natural hazards as related to climate change</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C14A..02M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C14A..02M"><span>Bathymetry and retreat of Southeast Greenland <span class="hlt">glaciers</span> from Operation IceBridge and Ocean Melting Greenland data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Millan, R.; Rignot, E. J.; Morlighem, M.; Bjork, A. A.; Mouginot, J.; Wood, M.</p> <p>2017-12-01</p> <p>Southeast Greenland has been one of the largest contributors to ice mass loss in Greenland in part because of significant changes in <span class="hlt">glacier</span> dynamics. The leading hypothesis for the changes in <span class="hlt">glacier</span> dynamics is that enhanced thermal forcing from the ocean has dislodged a number of <span class="hlt">glaciers</span> from their anchoring positions and some of them retreated rapidly along a reverse bed. The <span class="hlt">glaciers</span> response has been observed to vary significantly from one fjord to the next, but until now there was not enough data to understand or interpret these changes. In particular, there was no data on <span class="hlt">glacier</span> bed topography and seafloor bathymetry in the fjords. Here we present the results of new fjord mapping by the NASA Ocean Melting Greenland mission combined with a recent high-resolution airborne gravity survey by NASA Operation IceBridge. We combine these data with a reconstruction of the bed using a mass conservation approach upstream extending into the glacial fjords for the first time. In the fjord and along the ice-ocean transition, we employ a 3D inversion of gravity data to infer the bed elevation along a set of 9 survey boxes spanning south of Helheim <span class="hlt">Glacier</span> to the southern tip of Southeast Greenland. We combine the results with an analysis of the <span class="hlt">glacier</span> front history since the 1930's and Conductivity Temperature Depth data obtained in the fjord by OMG in 2016. The data reveals bed elevations several 100-m deeper than previously thought, for almost all the <span class="hlt">glaciers</span>, up to 500 m for some of them. For many <span class="hlt">glaciers</span>, the bed profiles help to completely understand the history of retreat of the <span class="hlt">glaciers</span>. For instance, <span class="hlt">glaciers</span> stranded on sills have been stable; <span class="hlt">glaciers</span> on a reverse slope have retreated rapidly; and <span class="hlt">glaciers</span> with a normal slope have retreated slowly. The mapping also helps document the extent of the marine portion of the <span class="hlt">glacier</span> <span class="hlt">basins</span>. In many of the fjords, we document the presence of warm, salty Atlantic Water which fuels large melt rates. We employ</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.2320I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.2320I"><span>Glacialmorphological reconstruction of <span class="hlt">glacier</span> advances and glacial lake outburst floods at the Cachapoal <span class="hlt">glacier</span> in the Dry Central Andes of Chile (34°S)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Iturrizaga, Lasafam; Charrier, Reynaldo</p> <p>2013-04-01</p> <p>Throughout the Andes Mountain range of South America a general trend of <span class="hlt">glacier</span> shrinkage has taken place in the last century. Only a few <span class="hlt">glaciers</span> have shown a rather <span class="hlt">non</span>-continuous trend of <span class="hlt">glacier</span> retreat and temporally advanced or even surged during the mid-19th to 20th century. One of the earliest assumed <span class="hlt">glacier</span> surges has occurred in the upper Cachapoal catchment area at the homonymous <span class="hlt">glacier</span>. In climatic respect the Cachapoal <span class="hlt">glacier</span> is located in the transition zone from the most southern part of the Dry Central Andes of Chile to the more humid zone of the Wet Andes. The region is affected mainly by winter precipitation deriving from the Westerlies. The debris-covered, 12 km-long Cachapoal <span class="hlt">glacier</span> represents one of the largest valley <span class="hlt">glaciers</span> in the Central Andes. It is an avalanche-fed <span class="hlt">glacier</span> with an almost 1500 m-high head wall in its upper catchment area flowing down from Picos del Barroso (5180 m) and terminates at an elevation of 2630 m a.s.l. with a bifurcated <span class="hlt">glacier</span> tongue. A large moraine complex, almost 2 km in length and 500 m in width, separates the two <span class="hlt">glacier</span> lobes. During times of advanced <span class="hlt">glacier</span> tongue positions the Ríos Molina and Cachapoal may be have blocked independently at two distinct localities which are situated about 2300 m apart from each other. A blockage with temporal lake formation has occurred at least in the years 1848, 1955 and 1981 (cf. Plagemann 1887, Peña 1981), from which the rupture of the earliest <span class="hlt">glacier</span> barrier has been the most devastating. This event is locally reminded as "la gran avenida en seco" in the historical record. Geomorphological evidence of the past historical and modern <span class="hlt">glacier</span> expansions is given in the proglacial area by a fresh dead-ice hummocky topography and glacial trimlines at the valley flanks. More down valley broad outwash plains and boulder clusters indicate past high energy floods produced by <span class="hlt">glacier</span> lake outbursts. Regarding the small size of the catchment area of the Río Molina</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RvGeo..54..220T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RvGeo..54..220T"><span>Where <span class="hlt">glaciers</span> meet water: Subaqueous melt and its relevance to <span class="hlt">glaciers</span> in various settings</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Truffer, Martin; Motyka, Roman J.</p> <p>2016-03-01</p> <p><span class="hlt">Glacier</span> change is ubiquitous, but the fastest and largest magnitude changes occur in <span class="hlt">glaciers</span> that terminate in water. This includes the most rapidly retreating <span class="hlt">glaciers</span>, and also several advancing ones, often in similar regional climate settings. Furthermore, water-terminating <span class="hlt">glaciers</span> show a large range in morphology, particularly when ice flow into ocean water is compared to that into freshwater lakes. All water-terminating <span class="hlt">glaciers</span> share the ability to lose significant volume of ice at the front, either through mechanical calving or direct melt from the water in contact. Here we present a review of the subaqueous melt process. We discuss the relevant physics and show how different physical settings can lead to different glacial responses. We find that subaqueous melt can be an important trigger for <span class="hlt">glacier</span> change. It can explain many of the morphological differences, such as the existence or absence of floating tongues. Subaqueous melting is influenced by glacial runoff, which is largely a function of atmospheric conditions. This shows a tight connection between atmosphere, oceans and lakes, and <span class="hlt">glaciers</span>. Subaqueous melt rates, even if shown to be large, should always be discussed in the context of ice supply to the <span class="hlt">glacier</span> front to assess its overall relevance. We find that melt is often relevant to explain seasonal evolution, can be instrumental in shifting a <span class="hlt">glacier</span> into a different dynamical regime, and often forms a large part of a <span class="hlt">glacier</span>'s mass loss. On the other hand, in some cases, melt is a small component of mass loss and does not significantly affect <span class="hlt">glacier</span> response.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.H43C1654B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.H43C1654B"><span>Response of small <span class="hlt">glaciers</span> to climate change: runoff from <span class="hlt">glaciers</span> of the Wind River range, Wyoming</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bliss, A. K.; Stamper, B.</p> <p>2017-12-01</p> <p>Runoff from <span class="hlt">glaciers</span> affects downstream ecosystems by influencing the quantity, seasonality, and chemistry of the water. We describe the present state of <span class="hlt">glaciers</span> in the Wind River range, Wyoming and consider how these <span class="hlt">glaciers</span> will change in the future. Wind River <span class="hlt">glaciers</span> have been losing mass in recent decades, as seen with geodetic techniques and by examining <span class="hlt">glacier</span> morphology. Interestingly, the 2016/7 winter featured one of the largest snowfalls on record. Our primary focus is the Dinwoody <span class="hlt">Glacier</span> ( 3 km^2, 3300-4000 m above sea level). We present data collected in mid-August 2017 including <span class="hlt">glacier</span> ablation rates, snow line elevations, and streamflow. We compare measured <span class="hlt">glacier</span> mass loss to streamflow at the <span class="hlt">glacier</span> terminus and at a USGS stream gauge farther downstream. Using a hydrological model, we explore the fate of glacial runoff as it moves into downstream ecosystems and through ranchlands important to local people. The techniques used here can be applied to similar small-<span class="hlt">glacier</span> systems in other parts of the world.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C13E..01B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C13E..01B"><span>Ocean forcing drives <span class="hlt">glacier</span> retreat sometimes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bassis, J. N.; Ultee, E.; Ma, Y.</p> <p>2015-12-01</p> <p>Observations show that marine-terminating <span class="hlt">glaciers</span> respond to climate forcing nonlinearly, with periods of slow or negligible <span class="hlt">glacier</span> advance punctuated by abrupt, rapid retreat. Once <span class="hlt">glacier</span> retreat has initiated, <span class="hlt">glaciers</span> can quickly stabilize with a new terminus position. Alternatively, retreat can be sustained for decades (or longer), as is the case for Columbia <span class="hlt">Glacier</span>, Alaska where retreat initiated ~1984 and continues to this day. Surprisingly, patterns of <span class="hlt">glacier</span> retreat show ambiguous or even contradictory correlations with atmospheric temperature and <span class="hlt">glacier</span> surface mass balance. Despite these puzzles, observations increasingly show that intrusion of warm subsurface ocean water into fjords can lead to <span class="hlt">glacier</span> erosion rates that can account for a substantial portion of the total mass lost from <span class="hlt">glaciers</span>. Here we use a simplified flowline model to show that even relatively modest submarine melt rates (~100 m/a) near the terminus of grounded <span class="hlt">glaciers</span> can trigger large increases in iceberg calving leading to rapid <span class="hlt">glacier</span> retreat. However, the strength of the coupling between submarine melt and calving is a strong function of the geometry of the <span class="hlt">glacier</span> (bed topography, ice thickness and <span class="hlt">glacier</span> width). This can lead to irreversible retreat when the terminus is thick and grounded deeply beneath sea level or result in little change when the <span class="hlt">glacier</span> is relatively thin, grounded in shallow water or pinned in a narrow fjord. Because of the strong dependence on <span class="hlt">glacier</span> geometry, small perturbations in submarine melting can trigger <span class="hlt">glaciers</span> in their most advanced—and geometrically precarious—state to undergo sudden retreat followed by much slower re-advance. Although many details remain speculative, our model hints that some <span class="hlt">glaciers</span> are more sensitive than others to ocean forcing and that some of the nonlinearities of <span class="hlt">glacier</span> response to climate change may be attributable to variations in difficult-to-detect subsurface water temperatures that need to be better</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRF..120.1530M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRF..120.1530M"><span>End-of-winter snow depth variability on <span class="hlt">glaciers</span> in Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McGrath, Daniel; Sass, Louis; O'Neel, Shad; Arendt, Anthony; Wolken, Gabriel; Gusmeroli, Alessio; Kienholz, Christian; McNeil, Christopher</p> <p>2015-08-01</p> <p>A quantitative understanding of snow thickness and snow water equivalent (SWE) on <span class="hlt">glaciers</span> is essential to a wide range of scientific and resource management topics. However, robust SWE estimates are observationally challenging, in part because SWE can vary abruptly over short distances in complex terrain due to interactions between topography and meteorological processes. In spring 2013, we measured snow accumulation on several <span class="hlt">glaciers</span> around the Gulf of Alaska using both ground- and helicopter-based ground-penetrating radar surveys, complemented by extensive ground truth observations. We found that SWE can be highly variable (40% difference) over short spatial scales (tens to hundreds of meters), especially in the ablation zone where the underlying ice surfaces are typically rough. Elevation provides the dominant <span class="hlt">basin</span>-scale influence on SWE, with gradients ranging from 115 to 400 mm/100 m. Regionally, total accumulation and the accumulation gradient are strongly controlled by a <span class="hlt">glacier</span>'s distance from the coastal moisture source. Multiple linear regressions, used to calculate distributed SWE fields, show that robust results require adequate sampling of the true distribution of multiple terrain parameters. Final SWE estimates (comparable to winter balances) show reasonable agreement with both the Parameter-elevation Relationships on Independent Slopes Model climate data set (9-36% difference) and the U.S. Geological Survey Alaska Benchmark <span class="hlt">Glaciers</span> (6-36% difference). All the <span class="hlt">glaciers</span> in our study exhibit substantial sensitivity to changing snow-rain fractions, regardless of their location in a coastal or continental climate. While process-based SWE projections remain elusive, the collection of ground-penetrating radar (GPR)-derived data sets provides a greatly enhanced perspective on the spatial distribution of SWE and will pave the way for future work that may eventually allow such projections.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986QuRes..26...27P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986QuRes..26...27P"><span>Pattern and forcing of Northern Hemisphere <span class="hlt">glacier</span> variations during the last millennium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Porter, Stephen C.</p> <p>1986-07-01</p> <p>Time series depicting mountain <span class="hlt">glacier</span> fluctuations in the Alps display generally similar patterns over the last two centuries, as do chronologies of <span class="hlt">glacier</span> variations for the same interval from elsewhere in the Northern Hemisphere. Episodes of <span class="hlt">glacier</span> advance consistently are associated with intervals of high average volcanic aerosol production, as inferred from acidity variations in a Greenland ice core. Advances occur whenever acidity levels rise sharply from background values to reach concentrations ≥1.2 μequiv H +/kg above background. A phase lag of about 10-15 yr, equivalent to reported response lags of Alpine <span class="hlt">glacier</span> termini, separates the beginning of acidity increases from the beginning of subsequent ice advances. A similar relationship, but based on limited and less-reliable historical data and on lichenometric ages, is found for the preceding 2 centuries. Calibrated radiocarbon dates related to advances of <span class="hlt">non</span>-calving and <span class="hlt">non</span>-surging <span class="hlt">glaciers</span> during the earlier part of the Little Ice Age display a comparable consistent pattern. An interval of reduced acidity values between about 1090 and 1230 A.D. correlates with a time of inferred <span class="hlt">glacier</span> contraction during the Medieval Optimum. The observed close relation between Noothern Hemisphere <span class="hlt">glacier</span> fluctuations and variations in Greenland ice-core acidity suggests that sulfur-rich aerosols generated by volcanic eruptions are a primary forcing mechanism of <span class="hlt">glacier</span> fluctuations, and therefore of climate, on a decadal scale. The amount of surface cooling attributable to individual large eruptions or to episodes of eruptions is simlar to the probable average temperature reduction during culminations of Little Ice Age alacier advances (ca. 0.5°-1.2°C), as inferred from depression of equilibrium-line altitudes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018QSRv..185...27G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018QSRv..185...27G"><span>People, lakes and seashores: Studies from the Baltic Sea <span class="hlt">basin</span> and <span class="hlt">adjacent</span> areas in the early and Mid-Holocene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Groß, Daniel; Zander, Annabell; Boethius, Adam; Dreibrodt, Stefan; Grøn, Ole; Hansson, Anton; Jessen, Catherine; Koivisto, Satu; Larsson, Lars; Lübke, Harald; Nilsson, Björn</p> <p>2018-04-01</p> <p>During the Early and Mid-Holocene significant changes in the ecology and socio-cultural spheres occurred around the Baltic Sea. Because of the underlying climatic changes and thus environmental alterations, the area was the scene for various cultural developments during the period under investigation. In the course of the melting of the <span class="hlt">glaciers</span> at the end of the last Ice Age, isostatic and eustatic movements caused continual changes to the Baltic Sea <span class="hlt">basin</span>. Changes in water level, however, affected not only the Early and Mid-Holocene coastlines, but also the whole Baltic Sea drainage system, including large lakes, rivers and watersheds in the hinterland were also dramatically impacted by these ecological changes. Prehistoric people were thus affected by changes in resource availability and reduction or enlargement of their territories, respectively. In order to evaluate the impact of changes in the water and land networks on the environment, resource availability, and human behaviour, and to reconstruct human responses to these changes, we pursue an interdisciplinary approach connecting environmental and archaeological research highlighted through different case studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SPIE.9998E..06Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPIE.9998E..06Z"><span><span class="hlt">Glacier</span> stagnant in central Karakorum during 2003 to 2008 derived from DEOS Mass Transport Model GRACE data and one monthly degree-day model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Xiaowen; Zhang, Shiqiang; Xu, Junli</p> <p>2016-10-01</p> <p><span class="hlt">Glacier</span> change in central Karakorum is known as `anomony' in the late 1990s, where many <span class="hlt">glaciers</span> expanded and numbers of <span class="hlt">glacier</span> surged while most of <span class="hlt">glaciers</span> in the Greater Himalaya rapidly retreated. However, the understanding of <span class="hlt">glacier</span> change in this region is still poor. <span class="hlt">Glacier</span> changes for the Hunza river <span class="hlt">basin</span> (HRB) in central Karakorum during 2003 to 2008 were investigated from different data sources. The mass variation in HRB were estimated from the DEOS Mass Transport Model (DMT-1) GRACE data and the Variable Infiltration Capacity (VIC) model, and compared with the simulated <span class="hlt">glacier</span> mass balance by one monthly degree-day model. The surface elevation difference of <span class="hlt">glaciers</span> between ASTER DEM and SRTM were calculated. The mass variations from GRACE data suggest that the <span class="hlt">glacier</span> mass balance in HRB during 2003-2007 has no clear trend. The cumulative mass balance is positive during 2003-2008. The average <span class="hlt">glacier</span> surface elevation difference between SRTM DEM and ASTER DEM is 11.8+/-3.2 m. The average differences of <span class="hlt">glacier</span> surface elevation of Batura <span class="hlt">glaciers</span> in accumulation zones is increased with 0.88m.a-1, These results indicate that there is no significant <span class="hlt">glacier</span> retreat during 1999 to 2008. The seasonal amplitude of simulated mass variation of the monthly degree-day model agreed well with that estimated from DMT-1 GRACE data, but the simulated <span class="hlt">glacier</span> accumulation is less than that calculated from GRACE data. The main reason probably lies in that the precipitation of <span class="hlt">glaciers</span> and ungalciated areas were underestimated, especially in alpine areas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016TCry...10...87C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016TCry...10...87C"><span>Ablation from calving and surface melt at lake-terminating Bridge <span class="hlt">Glacier</span>, British Columbia, 1984-2013</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chernos, M.; Koppes, M.; Moore, R. D.</p> <p>2016-01-01</p> <p>Bridge <span class="hlt">Glacier</span> is a lake-calving <span class="hlt">glacier</span> in the Coast Mountains of British Columbia and has retreated over 3.55 km since 1972. The majority of this retreat has occurred since 1991. This retreat is substantially greater than what has been inferred from regional climate indices, suggesting that it has been driven primarily by calving as the <span class="hlt">glacier</span> retreated across an overdeepened <span class="hlt">basin</span>. In order to better understand the primary drivers of ablation, surface melt (below the equilibrium line altitude, ELA) and calving were quantified during the 2013 melt season using a distributed energy balance model (DEBM) and time-lapse imagery. Calving, estimated using areal change, velocity measurements, and assuming flotation were responsible for 23 % of the <span class="hlt">glacier</span>'s ablation below the ELA during the 2013 melt season and were limited by modest flow speeds and a small terminus cross-section. Calving and surface melt estimates from 1984 to 2013 suggest that calving was consistently a smaller contributor of ablation. Although calving was estimated to be responsible for up to 49 % of the <span class="hlt">glacier</span>'s ablation for individual seasons, averaged over multiple summers it accounted between 10 and 25 %. Calving was enhanced primarily by buoyancy and water depths, and fluxes were greatest between 2005 and 2010 as the <span class="hlt">glacier</span> retreated over the deepest part of Bridge Lake. The recent rapid rate of calving is part of a transient stage in the <span class="hlt">glacier</span>'s retreat and is expected to diminish within 10 years as the terminus recedes into shallower water at the proximal end of the lake. These findings are in line with observations from other lake-calving <span class="hlt">glacier</span> studies across the globe and suggest a common large-scale pattern in calving-induced retreat in lake-terminating alpine <span class="hlt">glaciers</span>. Despite enhancing glacial retreat, calving remains a relatively small component of ablation and is expected to decrease in importance in the future. Hence, surface melt remains the primary driver of ablation at Bridge</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C33A1178B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C33A1178B"><span>Dynamical adjustment of Scandinavian <span class="hlt">glacier</span> mass-balance time series</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bonan, D.; Christian, J. E.; Christianson, K. A.</p> <p>2017-12-01</p> <p><span class="hlt">Glacier</span> mass wastage is often cited as one of the most visible manifestations of anthropogenic climate change. Annual <span class="hlt">glacier</span> mass-balance is related to local climate and atmospheric circulation, as it is defined as the yearly sum of accumulation and ablation—processes that are strongly influenced by year-to-year fluctuations in precipitation and temperature. <span class="hlt">Glacier</span> response to a climatic trend can, however, be masked by internal variability in atmospheric circulation, and by <span class="hlt">non</span>-climatic factors (such as topographic control, wind deposition, and incident solar radiation). Thus, unambiguous attribution of a negative <span class="hlt">glacier</span> mass-balance trend to anthropogenic forcing remains challenging. Maritime <span class="hlt">glacier</span> mass-balance records may be especially difficult to interpret due to the high winter balances from decadal-scale climate oscillations and the relatively short time series. Here we examine the influence of climate and atmospheric circulation variability on 14 Norwegian <span class="hlt">glaciers</span> that span 20° of latitude, from southern Norway to Svalbard. We use dynamical adjustment—a statistical method based on partial least squares regression—to identify the components of variability within the mass-balance records that are associated with the time-varying sea level pressure (SLP) and sea surface temperature (SST) fields. We find that 30-50% of the variance in the winter mass-balance records of the <span class="hlt">glaciers</span> in southern Norway is explained by using sea level pressure as a predictor. The leading SLP predictor pattern mimics the spatial signature of the North Atlantic Oscillation (NAO), indicating that winter balance is strongly influenced by the NAO. Moreover, the adjusted mass-balance records indicate a geographic trend: the southern Norwegian <span class="hlt">glaciers</span> have significant negative trends in the summer balance that remain negative after adjustment, while the more northern <span class="hlt">glaciers</span> have negative winter balance trends that only become significant after adjustment. We look into</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/29306','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/29306"><span>Great <span class="hlt">Basin</span> aspen ecosystems</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Dale L. Bartos</p> <p>2008-01-01</p> <p>The health of quaking aspen (Populus tremuloides) in the Great <span class="hlt">Basin</span> is of growing concern. The following provides an overview of aspen decline and die-off in areas within and <span class="hlt">adjacent</span> to the Great <span class="hlt">Basin</span> and suggests possible directions for research and management.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016WRR....52.3888B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016WRR....52.3888B"><span>High-resolution modeling of coastal freshwater discharge and <span class="hlt">glacier</span> mass balance in the Gulf of Alaska watershed</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beamer, J. P.; Hill, D. F.; Arendt, A.; Liston, G. E.</p> <p>2016-05-01</p> <p>A comprehensive study of the Gulf of Alaska (GOA) drainage <span class="hlt">basin</span> was carried out to improve understanding of the coastal freshwater discharge (FWD) and <span class="hlt">glacier</span> volume loss (GVL). Hydrologic processes during the period 1980-2014 were modeled using a suite of physically based, spatially distributed weather, energy-balance snow/ice melt, soil water balance, and runoff routing models at a high-resolution (1 km horizontal grid; daily time step). Meteorological forcing was provided by the North American Regional Reanalysis (NARR), Modern Era Retrospective Analysis for Research and Applications (MERRA), and Climate Forecast System Reanalysis (CFSR) data sets. Streamflow and <span class="hlt">glacier</span> mass balance modeled using MERRA and CFSR compared well with observations in four watersheds used for calibration in the study domain. However, only CFSR produced regional seasonal and long-term trends in water balance that compared favorably with independent Gravity Recovery and Climate Experiment (GRACE) and airborne altimetry data. Mean annual runoff using CFSR was 760 km3 yr-1, 8% of which was derived from the long-term removal of stored water from <span class="hlt">glaciers</span> (<span class="hlt">glacier</span> volume loss). The annual runoff from CFSR was partitioned into 63% snowmelt, 17% <span class="hlt">glacier</span> ice melt, and 20% rainfall. <span class="hlt">Glacier</span> runoff, taken as the sum of rainfall, snow, and ice melt occurring each season on <span class="hlt">glacier</span> surfaces, was 38% of the total seasonal runoff, with the remaining runoff sourced from nonglacier surfaces. Our simulations suggests that existing GRACE solutions, previously reported to represent <span class="hlt">glacier</span> mass balance alone, are actually measuring the full water budget of land and ice surfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.C21D..01S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.C21D..01S"><span>A linked lake system beneath Thwaites <span class="hlt">Glacier</span>, West Antarctica reveals an efficient mechanism for subglacial water flow.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, B. E.; Gourmelen, N.; Huth, A.; Joughin, I. R.</p> <p>2016-12-01</p> <p>In this presentation we show the results of a multi-sensor survey of a system of subglacial lakes beneath Thwaites <span class="hlt">Glacier</span>, West Antarctica. This is the first substantial active (meaning draining or filling on annual time scales) lake system detected under the fast-flowing <span class="hlt">glaciers</span> of the Amundsen Coast. Altimetry data show that over the 2013 calendar year, four subglacial lakes drained, essentially simultaneously, with the bulk of the drainage taking place over the course the first three months of the year. The largest of the lakes appears to have drained around 3.7 km3 of water, with the others each draining less than 1 km3. The high-resolution radar surveys conducted in this area by NASA's IceBridge program allow detailed analysis of the subglacial hydrologic potential, which shows that the potential map in this area is characterized by small closed <span class="hlt">basins</span> that should not, under the common assumption that water flow is directed down the gradient of the hydropotential, allow long-range water transport. The lakes' discharge demonstrates that, at least in some cases, water can flow out of apparently closed hydropotential <span class="hlt">basins</span>. Combining a basal-flow routing map with a map of basal melt production suggests that the largest drainage event could recur as often as every 22 years, provided that overflow or leakage of mapped hydropotential <span class="hlt">basins</span> allows melt water transport to refill the lake. An analysis of ice-surface speed records both around the lakes and at the Thwaites grounding line shows small changes in ice speed, but none clearly associated with the drainage event, suggesting that, at least in this area where subglacial melt is abundant, the addition of further water to the subglacial hydrologic system need not have any significant effect on ice flow. It is likely that the main impact of the lake system on the <span class="hlt">glacier</span> is that as an efficient mechanism to remove meltwater from the system, it drains water that would otherwise flow through less efficient</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....3741S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....3741S"><span>Assessment of Greenland Outlet <span class="hlt">Glacier</span> Albedo Variability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stroeve, J.</p> <p>2003-04-01</p> <p>Recent studies have shown that the coastal regions of the Greenland ice sheet are thinning rapidly. Analysis of passive microwave satellite data since 1979 have revealed a corresponding positive trend in the areal extent of melt. This trend was emphasized in 2002, when the total area of surface melt on the Greenland ice sheet surpased the maximum melt extent from the past 24 years by more than 9%. Increases in coastal temperatures have certainly contributed to melting near the margins. However, the high rate of thinning in the coastal regions, up to several m/yr, cannot be explained by increases in temperatures alone. Some of the thinning is likely creep thinning resulting from discharge velocities that exceed balance velocities. In order to better understand the role of ablation in the recent thinning rates, the variability in the surface albedo at four outlet <span class="hlt">glaciers</span> is analyzed from 1981 to 2000 using the AVHRR Polar Pathfinder data set. The four <span class="hlt">glaciers</span> analyzed are the following: Storstrommen (77N, 23W), Kangerdlugssuaq (68N, 33W), Petermann (81N, 62W) and Jakobshavn (69N, 50W). Clear sky albedo changes over time from May through September for the period 1981-2000 are presented. These months are chosen in order to capture the full cycle of melt onset and refreeze. The albedo record at the <span class="hlt">glaciers</span> shows large seasonal and interannual variability. Resuls indicate a steady decrease in surface albedo during the summer months from 1981 to 2000, particularly in the Jakobshavn drainage <span class="hlt">basin</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.water.usgs.gov/ofr2004-1069/','USGSPUBS'); return false;" href="http://pubs.water.usgs.gov/ofr2004-1069/"><span>A 30-year record of surface mass balance (1966-95) and motion and surface altitude (1975-95) at Wolverine <span class="hlt">Glacier</span>, Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Mayo, Lawrence R.; Trabant, Dennis C.; March, Rod S.</p> <p>2004-01-01</p> <p>Scientific measurements at Wolverine <span class="hlt">Glacier</span>, on the Kenai Peninsula in south-central Alaska, began in April 1966. At three long-term sites in the research <span class="hlt">basin</span>, the measurements included snow depth, snow density, heights of the <span class="hlt">glacier</span> surface and stratigraphic summer surfaces on stakes, and identification of the surface materials. Calculations of the mass balance of the surface strata-snow, new firn, superimposed ice, and old firn and ice mass at each site were based on these measurements. Calculations of fixed-date annual mass balances for each hydrologic year (October 1 to September 30), as well as net balances and the dates of minimum net balance measured between time-transgressive summer surfaces on the <span class="hlt">glacier</span>, were made on the basis of the strata balances augmented by air temperature and precipitation recorded in the <span class="hlt">basin</span>. From 1966 through 1995, the average annual balance at site A (590 meters altitude) was -4.06 meters water equivalent; at site B (1,070 meters altitude), was -0.90 meters water equivalent; and at site C (1,290 meters altitude), was +1.45 meters water equivalent. Geodetic determination of displacements of the mass balance stake, and <span class="hlt">glacier</span> surface altitudes was added to the data set in 1975 to detect the <span class="hlt">glacier</span> motion responses to variable climate and mass balance conditions. The average surface speed from 1975 to 1996 was 50.0 meters per year at site A, 83.7 meters per year at site B, and 37.2 meters per year at site C. The average surface altitudes were 594 meters at site A, 1,069 meters at site B, and 1,293 meters at site C; the <span class="hlt">glacier</span> surface altitudes rose and fell over a range of 19.4 meters at site A, 14.1 meters at site B, and 13.2 meters at site C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22304.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22304.html"><span>Khurdopin <span class="hlt">Glacier</span>, Pakistan</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2018-03-26</p> <p>In October 2016, the Khurdopin <span class="hlt">Glacier</span> in Pakistan began a rapid surge after 20 years of little movement. By March, 2017, a large lake had formed in the Shimshal River, where the <span class="hlt">glacier</span> had formed a dam. Fortunately, the river carved an outlet through the <span class="hlt">glacier</span> before the lake could empty catastrophically. In this pair of ASTER images, acquired August 20, 2015 and May 21, 2017, the advance of the Khurdopin <span class="hlt">Glacier</span> (dark gray and white "river" in lower right quarter of image) is obvious by comparing the before and after images. The images cover an area of 25 by 27.8 km, and are located at 36.3 degrees north, 75.5 degrees east. https://photojournal.jpl.nasa.gov/catalog/PIA22304</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.1556S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.1556S"><span>Is organic matter found in <span class="hlt">glaciers</span> similar to soil organic matter? A detailed molecular-level investigation of organic matter found in cryoconite holes on the Athabasca <span class="hlt">Glacier</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Simpson, M. J.; Xu, Y.; Eyles, N.; Simpson, A. J.; Baer, A.</p> <p>2009-04-01</p> <p> indicate that windblown or meltwater fluvial OM rich materials from <span class="hlt">adjacent</span> peatlands or mosses and lichens developed on tundra soils can be trapped and preserved in cryoconite holes in <span class="hlt">glaciers</span> and may be an important mechanism for promoting active bacterial colonies in glacial environments both modern and ancient. Given that such material is incorporated within the <span class="hlt">glacier</span> in the accumulation zone or flushed by meltwaters into subglacial environments, reworked COM may provide nutrient sources for active microbial communities found within and under <span class="hlt">glaciers</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMPA54A..06M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMPA54A..06M"><span>Developing Aesthetically Compelling Visualizations for Documenting and Communicating Alaskan <span class="hlt">Glacier</span> and Landscape Change</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Molnia, B. F.</p> <p>2016-12-01</p> <p>For 50 years I have investigated <span class="hlt">glacier</span> dynamics and attempted to convey this information to others. Since 2000, my focus has been on capturing and documenting decadal and century-scale Alaskan <span class="hlt">glacier</span> and landscape change using precision repeat photography and on broadly communicate these results through simple, aesthetically compelling, unambiguous visualizations. As a young geologist, I spent the summer of 1968 on the Juneau Icefield, photographing its surface features and margins. Since then, I have taken 150,000 photographs of Alaskan <span class="hlt">glaciers</span> and collected 5,000 historical Alaskan photographs taken by other, the earliest dating back to 1883. This database and my passion for photographing <span class="hlt">glaciers</span> became the basis for an on-going investigation aimed at visually documenting <span class="hlt">glacier</span> and landscapes change at more than 200 previously photographed Alaskan locations in <span class="hlt">Glacier</span> Bay and Kenai Fjords National Parks, Prince William Sound, and the Coast Mountains. Repeat photography is a technique in which a historical and a modern photograph, both having similar fields of view, are compared and contrasted to quantitatively and qualitatively determine their similarities and differences. In precision repeat photography, both photographs have the same field of view, ideally being photographed from the identical location. Since 2000, I have conducted nearly 20 field campaigns to systematically revisit and re-photograph more than 225 fields of view previously captured in the historical photographs. As aesthetics are important in successfully communicating what has changed, substantial time and effort is invested in capturing new, comparable, generally cloud free photographs at each revisited site. The resulting modern images are then paired with similar field-of-view historical images to produce compelling, aesthetic photo pairs which depict long-term <span class="hlt">glacier</span>, landscape, and ecosystem changes. As a few sites have multiple historical images, photo triplets or quadruplets are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.C13B0827S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.C13B0827S"><span>Long term measurements of light absorbing particles on tropical <span class="hlt">glaciers</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmitt, C. G.; Sanchez Rodriguez, W.; Arnott, W. P.; All, J.; Schwarz, J. P.</p> <p>2016-12-01</p> <p>We present results of six years of measurements of light absorbing particles (LAP) on <span class="hlt">glaciers</span> of the Cordillera Blanca mountain range in Peru. Tropical <span class="hlt">glaciers</span> are important sources of water for human consumption, agriculture, and hydroelectric power in the region. Regular measurements in the dry season show that light absorbing particle concentrations are generally low (equivalent to the absorption equivalent of 5-30 nanograms of black carbon per gram of snow) during <span class="hlt">non</span>-El Nino years while values increase substantially during the recent El Nino. Two years of monthly measurements at two <span class="hlt">glaciers</span> show that fresh snow LAP concentration are very low while LAP levels increase dramatically during snow-less periods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1915975N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1915975N"><span><span class="hlt">Glacier</span> Changes in the Nanga Parbat Region, NW Himalaya: A longitudinal study over 160 years (1856-2016)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nüsser, Marcus; Schmidt, Susanne</p> <p>2017-04-01</p> <p>Against the background of the prominent Himalayan <span class="hlt">glacier</span> debate of the past decade, global concerns were raised about the severe consequences of detected and expected changes in the South Asian cryosphere. Due to the lack of historical glaciological data in the Himalayan region, studies of <span class="hlt">glacier</span> changes over long time periods are rare. The present study seeks to analyze and quantify <span class="hlt">glacier</span> changes in the Nanga Parbat region between 1856 and 2016. Due to the steep topography and great vertical span, the debris-covered <span class="hlt">glaciers</span> of the mountain massif are largely fed by avalanches of different size. This impact of snow and ice re-distribution by avalanches is often neglected in <span class="hlt">glacier</span> mass-balances. Therefore, an integrated approach was used to investigate the <span class="hlt">glacier</span> changes and the impact of avalanches. This approach includes (1) a re-photographic survey with images from several expeditions between 1934 and 2010, (2) mapping during own field surveys between 1992 and 2010, as well as (3) the analyses of remote sensing data (Corona, QuickBird, KompSat, Landsat, etc. and DEM) and (4) historical topographic maps. The re-photographic survey allows for direct comparisons and illustrates <span class="hlt">glacier</span> changes over a span of seventy years. Changes of <span class="hlt">glacier</span> lengths were quantified by using remote sensing data and the topographic map of 1934. In order to calculate <span class="hlt">glacier</span> surface changes, a digital elevation model (DEM) with a spatial resolution of 30 x 30 m2 was derived from the digitized contour lines of the topographic map from 1934 and compared to SRTM-DEM (30 x 30 m2) and ALOS-DSM. Based on remote sensing time-series, avalanche deposits on <span class="hlt">glaciers</span> were mapped in order to identify their magnitude and frequencies. To calculate the potential <span class="hlt">glacier</span> catchment, area of steep rock walls and the ratio between accumulation and ablation zones were calculated for each <span class="hlt">glacier</span> <span class="hlt">basin</span>. Our field based investigations show that the <span class="hlt">glaciers</span> in the Rupal Valley are characterized by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1978/0783/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1978/0783/report.pdf"><span>Subsurface geology and porosity distribution, Madison Limestone and underlying formations, Powder River <span class="hlt">basin</span>, northeastern Wyoming and southeastern Montana and <span class="hlt">adjacent</span> areas</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Peterson, James A.</p> <p>1978-01-01</p> <p>To evaluate the Madison Limestone and associated rocks as potential sources for water supplies in the Powder River <span class="hlt">Basin</span> and <span class="hlt">adjacent</span> areas, an understanding of the geologic framework of these units, their lithologic facies patterns, the distribution of porosity zones, and the relation between porosity development and stratigraphic facies is necessary. Regionally the Madison is mainly a fossiliferous limestone. However, in broad areas of the eastern Rocky Mountains and western Great Plains, dolomite is a dominant constituent and in places the Madison is almost entirely dolomite. Within these areas maximum porosity development is found and it seems to be related to the coarser crystalline dolomite facies. The porosity development is associated with tabular and fairly continuous crystalline dolomite beds separated by <span class="hlt">non</span>-porous limestones. The maximum porosity development in the Bighorn Dolomite, as in the Madison, is directly associated with the occurrence of a more coarsely crystalline sucrosic dolomite facies. Well data indicate, however, that where the Bighorn is present in the deeper parts of the Powder River <span class="hlt">Basin</span>, it may be dominated by a finer crystalline dolomite facies of low porosity. The 'Winnipeg Sandstone' is a clean, generally well-sorted, medium-grained sandstone. It shows good porosity development in parts of the northern Powder River <span class="hlt">Basin</span> and northwestern South Dakota. Because the sandstone is silica-cemented and quartzitic in areas of deep burial, good porosity is expected only where it is no deeper than a few thousand feet. The Flathead Sandstone is a predominantly quartzose, slightly feldspathic sandstone, commonly cemented with iron oxide. Like the 'Winnipeg Sandstone,' it too is silica-cemented and quartzitic in many places so that its porosity is poor in areas of deep burial. Illustrations in this report show the thickness, percent dolomite, and porosity-feet for the Bighorn Dolomite and the Madison Limestone and its subdivisions. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750002467','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750002467"><span>Evaluate ERTS imagery for mapping and detection of changes of snowcover on land and on <span class="hlt">glaciers</span>. [Alaska and Washington</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Meier, M. F. (Principal Investigator)</p> <p>1973-01-01</p> <p>The author has identified the following significant results. A new procedure to determine snowcovered areas has been devised. Aside from problems in heavily forested areas this method shows promise in predicting snowmelt runoff from mountain areas and will also assist in energy balance modeling of large snowfields. Snowcover results compare favorably with measurements made by high altitude aircraft photography. Changes in snowcover in areas as small as 3 x 5 km can be determined from ERTS-1 images by both optical and electronic methods. Snowcover changes determined by these two methods in the experimental South Cascade <span class="hlt">Glacier</span> <span class="hlt">Basin</span> were verified by field mapping. Image enahancement techniques on ERTS-1 images of large Alaskan <span class="hlt">glaciers</span> (the Hubbard, Yentna, and Kahiltna) have given new insights into the large-scale structures and flow dynamics of these potentially hazardous <span class="hlt">glaciers</span>. The Hubbard <span class="hlt">Glacier</span>, in particular, is one which poses a threat to man and should be monitored for future changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://geology.geoscienceworld.org/content/38/4/319','USGSPUBS'); return false;" href="http://geology.geoscienceworld.org/content/38/4/319"><span><span class="hlt">Glacier</span> microseismicity</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>West, Michael E.; Larsen, Christopher F.; Truffer, Martin; O'Neel, Shad; LeBlanc, Laura</p> <p>2010-01-01</p> <p>We present a framework for interpreting small <span class="hlt">glacier</span> seismic events based on data collected near the center of Bering <span class="hlt">Glacier</span>, Alaska, in spring 2007. We find extremely high microseismicity rates (as many as tens of events per minute) occurring largely within a few kilometers of the receivers. A high-frequency class of seismicity is distinguished by dominant frequencies of 20–35 Hz and impulsive arrivals. A low-frequency class has dominant frequencies of 6–15 Hz, emergent onsets, and longer, more monotonic codas. A bimodal distribution of 160,000 seismic events over two months demonstrates that the classes represent two distinct populations. This is further supported by the presence of hybrid waveforms that contain elements of both event types. The high-low-hybrid paradigm is well established in volcano seismology and is demonstrated by a comparison to earthquakes from Augustine Volcano. We build on these parallels to suggest that fluid-induced resonance is likely responsible for the low-frequency <span class="hlt">glacier</span> events and that the hybrid <span class="hlt">glacier</span> events may be caused by the rush of water into newly opening pathways.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24824138','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24824138"><span>Changes in <span class="hlt">glaciers</span> in the Swiss Alps and impact on <span class="hlt">basin</span> hydrology: current state of the art and future research.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pellicciotti, F; Carenzo, M; Bordoy, R; Stoffel, M</p> <p>2014-09-15</p> <p>Switzerland is one of the countries with some of the longest and best glaciological data sets. Its <span class="hlt">glaciers</span> and their changes in response to climate have been extensively investigated, and the number and quality of related studies are notable. However, a comprehensive review of <span class="hlt">glacier</span> changes and their impact on the hydrology of glacierised catchments for Switzerland is missing and we use the opportunity provided by the EU-FP7 ACQWA project to review the current state of knowledge about past changes and future projections. We examine the type of models that have been applied to infer <span class="hlt">glacier</span> evolution and identify knowledge gaps that should be addressed in future research in addition to those indicated in previous publications. Common characteristics in long-term series of projected future <span class="hlt">glacier</span> runoff are an initial peak followed by a decline, associated with shifts in seasonality, earlier melt onset and reduced summer runoff. However, the quantitative predictions are difficult to compare, as studies differ in terms of model structure, calibration strategies, input data, temporal and spatial resolution as well as future scenarios used for impact studies. We identify two sources of uncertainties among those emerging from recent research, and use simulations over four <span class="hlt">glaciers</span> to: i) quantify the importance of the correct extrapolation of air temperature, and ii) point at the key role played by debris cover in modulating <span class="hlt">glacier</span> response. Copyright © 2014 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70048870','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70048870"><span>Active transtensional intracontinental <span class="hlt">basins</span>: Walker Lane in the western Great <span class="hlt">Basin</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Jayko, Angela S.; Bursik, Marcus</p> <p>2012-01-01</p> <p>The geometry and dimensions of sedimentary <span class="hlt">basins</span> within the Walker Lane are a result of Plio-Pleistocene transtensive deformation and partial detachment of the Sierra Nevada crustal block from the North American plate. Distinct morpho-tectonic domains lie within this active transtensive zone. The northeast end of the Walker Lane is partly buried by active volcanism of the southern Cascades, and <span class="hlt">adjacent</span> <span class="hlt">basins</span> are filled or poorly developed. To the south, the <span class="hlt">basin</span> sizes are moderate, 25–45km × 15–10 km, with narrow 8-12km wide mountain ranges mainly oriented N-S to NNE. These <span class="hlt">basins</span> form subparallel arrays in discrete zones trending about 300° and have documented clockwise rotation. This is succeeded to the south by a releasing stepover domain ∼85-100km wide, where the <span class="hlt">basins</span> are elongated E-W to ENE, small (∼15-30km long, 5-15km wide), and locally occupied by active volcanic centers. The southernmost part of the Walker Lane is structurally integrated, with high to extreme relief. <span class="hlt">Adjacent</span> <span class="hlt">basins</span> are elongate, 50-200km long and ∼5 -20km wide. Variations in transtensive <span class="hlt">basin</span> orientations in the Walker Lane are largely attributable to variations in strain partitioning. Large <span class="hlt">basins</span> in the Walker Lane have 2-6km displacement across <span class="hlt">basin</span> bounding faults with up to 3 km of clastic accumulation based on gravity and drill hole data. The sedimentary deposits of the <span class="hlt">basins</span> may include interbedded volcanic deposits with bimodal basaltic and rhyolitic associations. The <span class="hlt">basins</span> may include lacustrine deposits that record a wide range of water chemistry from cold fresh water conditions to saline-evaporative</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1913170F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1913170F"><span>Development of Adygine <span class="hlt">glacier</span> complex (<span class="hlt">glacier</span> and proglacial lakes) and its link to outburst hazard</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Falatkova, Kristyna; Schöner, Wolfgang; Häusler, Hermann; Reisenhofer, Stefan; Neureiter, Anton; Sobr, Miroslav; Jansky, Bohumir</p> <p>2017-04-01</p> <p>Mountain <span class="hlt">glacier</span> retreat has a well-known impact on life of local population - besides anxiety over water supply for agriculture, industry, or households, it has proved to have a direct influence on <span class="hlt">glacier</span> hazard occurrence. The paper focuses on lake outburst hazard specifically, and aims to describe the previous and future development of Adygine <span class="hlt">glacier</span> complex and identify its relationship to the hazard. The observed <span class="hlt">glacier</span> is situated in the Northern Tien Shan, with an area of 4 km2 in northern exposition at an elevation range of 3,500-4,200 m a.s.l. The study <span class="hlt">glacier</span> ranks in the group of small-sized <span class="hlt">glaciers</span>, therefore we expect it to respond faster to changes of the climate compared to larger ones. Below the <span class="hlt">glacier</span> there is a three-level cascade of proglacial lakes at different stages of development. The site has been observed sporadically since 1960s, however, closer study has been carried out since 2007. Past development of the <span class="hlt">glacier</span>-lake complex is analyzed by combination of satellite imagery interpretations and on-site measurements (geodetic and bathymetric survey). A <span class="hlt">glacier</span> mass balance model is used to simulate future development of the <span class="hlt">glacier</span> resulting from climate scenarios. We used the simulated future <span class="hlt">glacier</span> extent and the <span class="hlt">glacier</span> base topography provided by GPR survey to assess potential for future lake formation. This enables us to assess the outburst hazard for the three selected lakes with an outlook for possible/probable hazard changes linked to further complex succession/progression (originating from climate change scenarios). Considering the proximity of the capital Bishkek, spreading settlements, and increased demand for tourism-related infrastructure within the main valley, it is of high importance to identify the present and possible future hazards that have a potential to affect this region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992AIPC..277...61P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992AIPC..277...61P"><span>Changes in water supply in Alpine regions due to <span class="hlt">glacier</span> retreat</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pelto, Mauri S.</p> <p>1992-06-01</p> <p>In the late 1970s global temperature rose abruptly, and between 1977 and 1990 has averaged 0.4 °C above the 1940-76 mean. In 1980, 50% of the the alpine <span class="hlt">glaciers</span> observed in the Swiss Alps, Peruvian Andes, Norwegian Coast Range, Northern Caucasus and Washington's North Cascades were advancing. By 1990 in response to the warming only 15% were still advancing. During the peak <span class="hlt">non-glacier</span> snow melt period <span class="hlt">glaciers</span> are unsaturated aquifers soaking up and holding meltwater for the first two-six weeks of the melt season. This storage acts as a buffer for spring snow melt flooding, and spreads the peak spring flow over a longer period. In the late summer <span class="hlt">glaciers</span> buffer low flow periods by providing large volumes of meltwater. As <span class="hlt">glaciers</span> retreat the amount of water they can store decreases raising spring flood danger and the areal extend exposed for late summer meltwater generation decreases, thus reducing late summer flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA02670.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA02670.html"><span>Patagonia <span class="hlt">Glacier</span>, Chile</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2001-07-21</p> <p>This ASTER image was acquired on May 2, 2000 over the North Patagonia Ice Sheet, Chile near latitude 47 degrees south, longitude 73 degrees west. The image covers 36 x 30 km. The false color composite displays vegetation in red. The image dramatically shows a single large <span class="hlt">glacier</span>, covered with crevasses. A semi-circular terminal moraine indicates that the <span class="hlt">glacier</span> was once more extensive than at present. ASTER data are being acquired over hundreds of <span class="hlt">glaciers</span> worldwide to measure their changes over time. Since <span class="hlt">glaciers</span> are sensitive indicators of warming or cooling, this program can provide global data set critical to understand climate change. This image is located at 46.5 degrees south latitude and 73.9 degrees west longitude. http://photojournal.jpl.nasa.gov/catalog/PIA02670</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014TCD.....8.2491M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014TCD.....8.2491M"><span>The length of the <span class="hlt">glaciers</span> in the world - a straightforward method for the automated calculation of <span class="hlt">glacier</span> center lines</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Machguth, H.; Huss, M.</p> <p>2014-05-01</p> <p><span class="hlt">Glacier</span> length is an important measure of <span class="hlt">glacier</span> geometry but global <span class="hlt">glacier</span> inventories are mostly lacking length data. Only recently semi-automated approaches to measure <span class="hlt">glacier</span> length have been developed and applied regionally. Here we present a first global assessment of <span class="hlt">glacier</span> length using a fully automated method based on <span class="hlt">glacier</span> surface slope, distance to the <span class="hlt">glacier</span> margins and a set of trade-off functions. The method is developed for East Greenland, evaluated for the same area as well as for Alaska, and eventually applied to all ∼200 000 <span class="hlt">glaciers</span> around the globe. The evaluation highlights accurately calculated <span class="hlt">glacier</span> length where DEM quality is good (East Greenland) and limited precision on low quality DEMs (parts of Alaska). Measured length of very small <span class="hlt">glaciers</span> is subject to a certain level of ambiguity. The global calculation shows that only about 1.5% of all <span class="hlt">glaciers</span> are longer than 10 km with Bering <span class="hlt">Glacier</span> (Alaska/Canada) being the longest <span class="hlt">glacier</span> in the world at a length of 196 km. Based on model output we derive global and regional area-length scaling laws. Differences among regional scaling parameters appear to be related to characteristics of topography and <span class="hlt">glacier</span> mass balance. The present study adds <span class="hlt">glacier</span> length as a central parameter to global <span class="hlt">glacier</span> inventories. Global and regional scaling laws might proof beneficial in conceptual <span class="hlt">glacier</span> models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001485.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001485.html"><span><span class="hlt">Glaciers</span> and Sea Level Rise</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-08</p> <p>Calving front of the Perito Moreno <span class="hlt">Glacier</span> (Argentina). Contrary to the majority of the <span class="hlt">glaciers</span> from the southern Patagonian ice field, the Perito Moreno <span class="hlt">Glacier</span> is currently stable. It is also one of the most visited <span class="hlt">glaciers</span> in the world. To learn about the contributions of <span class="hlt">glaciers</span> to sea level rise, visit: www.nasa.gov/topics/earth/features/<span class="hlt">glacier</span>-sea-rise.html Credit: Etienne Berthier, Université de Toulouse NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. 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M.; Singh, V.; Linda, A.</p> <p>2016-12-01</p> <p>The present ongoing study is oriented to do the detailed study of the Patsio <span class="hlt">glacier</span> which is in the Bhaga <span class="hlt">Basin</span>, Lahaul, Himachal Pradesh. Patsio <span class="hlt">glacier</span> is a compound valley <span class="hlt">glacier</span> survived by two prominent tributaries namely Eastern and Western. The two tributaries are facing opposite to each other. The Western tributary facing almost eastward shows higher melting as compared to Eastern tributary facing northwest. This is probably due to solar radiation and sunshine hour, as Western tributary receives high solar radiation and for longer duration. A series of supraglacial lakes which were connected to each other through supra channels were observed on the upper part of the ablation zone at an altitude range of 5100 m and 5300 m amsl. A dead ice covered with thick debris was observed below the current terminus. Despite the large variability of the mass balance in the different seasons Patsio <span class="hlt">glacier</span> annual balance for the year 2012-2013 was found to be 0.04 ± 0.40 m w.e. the low values signifies that <span class="hlt">glacier</span> has lost significant amount of mass in recent past and now it is near to the equilibrium state. Seasonal mass balance of Patsio <span class="hlt">glacier</span> has shown wide range of variability in the mass balances. Patsio <span class="hlt">glacier</span> receives most of the accumulation during the winter months and duration is long whereas, ablation season is short but quite significant. Monthly and daily variation has depicted that peak ablation months are July and August. The daily ablation in the month of August 2013 was found to be around 5 cm per day, probably due to air temperature. To have a clear picture of the meteorological parameters and its relation with <span class="hlt">glacier</span> an AWS has set up on the Patsio <span class="hlt">glacier</span> at an altitude of 5050 m amsl in June 2014. Seasonal mass balance gradients show that gradient was high during the early and late ablation seasons as compared to peak ablation season. The mass balance for the year 2010-2011 was slightly positive.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1616386K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1616386K"><span>Modeling <span class="hlt">glacier</span> beds in the Austrian Alps: How many lakes will form in future?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koehler, Dominik; Geilhausen, Martin; Linsbauer, Andreas</p> <p>2014-05-01</p> <p>Glacial retreat exposes landscapes with relief characteristics greatly differing from the former ice covered surfaces. If glacial retreat exposes natural <span class="hlt">basins</span> capable of forming proglacial lakes, then the downstream hydrologic and geomorphic systems in such catchments will be significantly altered due to discharge modifications, sediment trapping, decoupling effects and long term sediment storage (e.g. Geilhausen et al. 2013). Further implications are related to hydropower management, tourism and natural hazards. Consequently, sound knowledge of present day <span class="hlt">glacier</span> beds ("proglacial zones of tomorrow") and in particular the total number, locations and characteristics of overdeepenings are of importance. For Austria, however, this important information about significant future changes of high alpine regions is yet missing. An interdisciplinary research project is currently in preparation to close this gap. This paper presents results of a pilot study. We used a novel GIS-based approach (GlabTop, cf. Linsbauer et al. 2012) to compute approximate <span class="hlt">glacier</span> beds in the Austrian Alps. GlabTop ('<span class="hlt">Glacier</span> bed Topography') is based on an empirical relation between average basal shear stress and elevation range of individual <span class="hlt">glaciers</span> and makes use of digital elevation models (DEM), <span class="hlt">glacier</span> outlines and branch lines (i.e. a set of lines covering all important <span class="hlt">glacier</span> branches). DEMs and <span class="hlt">glacier</span> outlines were derived from the Austrian <span class="hlt">glacier</span> inventory (1998) and branch lines were manually digitized. The inventory includes 911 <span class="hlt">glaciers</span> of which 876 (96%) were considered and 35 were excluded due to size restrictions (< 0.01 km²) or insufficient DEM coverage. We found 165 overdeepenings (> 0.01 km²) with the potential of forming proglacial lakes when <span class="hlt">glacier</span> retreat reveals the bed. The total area and volume of all overdeepenings is approx. 10 km² and 236 Mio m³ respectively and 33 lakes will be larger than 1 km³. A total <span class="hlt">glacier</span> volume of 16 ± 5 km³ with an average ice</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70029435','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70029435"><span>Local response of a <span class="hlt">glacier</span> to annual filling and drainage of an ice-marginal lake</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Walder, J.S.; Trabant, D.C.; Cunico, M.; Fountain, A.G.; Anderson, S.P.; Anderson, R. Scott; Malm, A.</p> <p>2006-01-01</p> <p>Ice-marginal Hidden Creek Lake, Alaska, USA, outbursts annually over the course of 2-3 days. As the lake fills, survey targets on the surface of the 'ice dam' (the <span class="hlt">glacier</span> <span class="hlt">adjacent</span> to the lake) move obliquely to the ice margin and rise substantially. As the lake drains, ice motion speeds up, becomes nearly perpendicular to the face of the ice dam, and the ice surface drops. Vertical movement of the ice dam probably reflects growth and decay of a wedge of water beneath the ice dam, in line with established ideas about jo??kulhlaup mechanics. However, the distribution of vertical ice movement, with a narrow (50-100 m wide) zone where the uplift rate decreases by 90%, cannot be explained by invoking flexure of the ice dam in a fashion analogous to tidal flexure of a floating <span class="hlt">glacier</span> tongue or ice shelf. Rather, the zone of large uplift-rate gradient is a fault zone: ice-dam deformation is dominated by movement along high-angle faults that cut the ice dam through its entire thickness, with the sense of fault slip reversing as the lake drains. Survey targets spanning the zone of steep uplift gradient move relative to one another in a nearly reversible fashion as the lake fills and drains. The horizontal strain rate also undergoes a reversal across this zone, being compressional as the lake fills, but extensional as the lake drains. Frictional resistance to fault-block motion probably accounts for the fact that lake level falls measurably before the onset of accelerated horizontal motion and vertical downdrop. As the overall fault pattern is the same from year to year, even though ice is lost by calving, the faults must be regularly regenerated, probably by linkage of surface and bottom crevasses as ice is advected toward the lake <span class="hlt">basin</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA13382.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA13382.html"><span>Susitna <span class="hlt">Glacier</span>, Alaska</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2010-09-13</p> <p>Folds in the lower reaches of valley <span class="hlt">glaciers</span> can be caused by powerful surges of tributary ice streams. This phenomenon is spectacularly displayed by the Sustina <span class="hlt">Glacier</span> in the Alaska Range as seen by NASA Terra spacecraft.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C33D1234M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C33D1234M"><span>The Open Global <span class="hlt">Glacier</span> Model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marzeion, B.; Maussion, F.</p> <p>2017-12-01</p> <p>Mountain <span class="hlt">glaciers</span> are one of the few remaining sub-systems of the global climate system for which no globally applicable, open source, community-driven model exists. Notable examples from the ice sheet community include the Parallel Ice Sheet Model or Elmer/Ice. While the atmospheric modeling community has a long tradition of sharing models (e.g. the Weather Research and Forecasting model) or comparing them (e.g. the Coupled Model Intercomparison Project or CMIP), recent initiatives originating from the glaciological community show a new willingness to better coordinate global research efforts following the CMIP example (e.g. the <span class="hlt">Glacier</span> Model Intercomparison Project or the <span class="hlt">Glacier</span> Ice Thickness Estimation Working Group). In the recent past, great advances have been made in the global availability of data and methods relevant for <span class="hlt">glacier</span> modeling, spanning <span class="hlt">glacier</span> outlines, automatized <span class="hlt">glacier</span> centerline identification, bed rock inversion methods, and global topographic data sets. Taken together, these advances now allow the ice dynamics of <span class="hlt">glaciers</span> to be modeled on a global scale, provided that adequate modeling platforms are available. Here, we present the Open Global <span class="hlt">Glacier</span> Model (OGGM), developed to provide a global scale, modular, and open source numerical model framework for consistently simulating past and future global scale <span class="hlt">glacier</span> change. Global not only in the sense of leading to meaningful results for all <span class="hlt">glaciers</span> combined, but also for any small ensemble of <span class="hlt">glaciers</span>, e.g. at the headwater catchment scale. Modular to allow combinations of different approaches to the representation of ice flow and surface mass balance, enabling a new kind of model intercomparison. Open source so that the code can be read and used by anyone and so that new modules can be added and discussed by the community, following the principles of open governance. Consistent in order to provide uncertainty measures at all realizable scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.C43C0686H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.C43C0686H"><span>Surge of a Complex <span class="hlt">Glacier</span> System - The Current Surge of the Bering-Bagley <span class="hlt">Glacier</span> System, Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Herzfeld, U. C.; McDonald, B.; Trantow, T.; Hale, G.; Stachura, M.; Weltman, A.; Sears, T.</p> <p>2013-12-01</p> <p>Understanding fast <span class="hlt">glacier</span> flow and glacial accelerations is important for understanding changes in the cryosphere and ultimately in sea level. Surge-type <span class="hlt">glaciers</span> are one of four types of fast-flowing <span class="hlt">glaciers</span> --- the other three being continuously fast-flowing <span class="hlt">glaciers</span>, fjord <span class="hlt">glaciers</span> and ice streams --- and the one that has seen the least amount of research. The Bering-Bagley <span class="hlt">Glacier</span> System, Alaska, the largest <span class="hlt">glacier</span> system in North America, surged in 2011 and 2012. Velocities decreased towards the end of 2011, while the surge kinematics continued to expand. A new surge phase started in summer and fall 2012. In this paper, we report results from airborne observations collected in September 2011, June/July and September/October 2012 and in 2013. Airborne observations include simultaneously collected laser altimeter data, videographic data, GPS data and photographic data and are complemented by satellite data analysis. Methods range from classic interpretation of imagery to analysis and classification of laser altimeter data and connectionist (neural-net) geostatistical classification of concurrent airborne imagery. Results focus on the characteristics of surge progression in a large and complex <span class="hlt">glacier</span> system (as opposed to a small <span class="hlt">glacier</span> with relatively simple geometry). We evaluate changes in surface elevations including mass transfer and sudden drawdowns, crevasse types, accelerations and changes in the supra-glacial and englacial hydrologic system. Supraglacial water in Bering <span class="hlt">Glacier</span> during Surge, July 2012 Airborne laser altimeter profile across major rift in central Bering <span class="hlt">Glacier</span>, Sept 2011</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA03475.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA03475.html"><span>Malaspina <span class="hlt">Glacier</span>, Alaska</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2002-02-26</p> <p>This image from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra satellite covers an area of 55 by 40 kilometers (34 by 25 miles) over the southwest part of the Malaspina <span class="hlt">Glacier</span> and Icy Bay in Alaska. The composite of infrared and visible bands results in the snow and ice appearing light blue, dense vegetation is yellow-orange and green, and less vegetated, gravelly areas are in orange. According to Dr. Dennis Trabant (U.S. Geological Survey, Fairbanks, Alaska), the Malaspina <span class="hlt">Glacier</span> is thinning. Its terminal moraine protects it from contact with the open ocean; without the moraine, or if sea level rises sufficiently to reconnect the <span class="hlt">glacier</span> with the ocean, the <span class="hlt">glacier</span> would start calving and retreat significantly. ASTER data are being used to help monitor the size and movement of some 15,000 tidal and piedmont <span class="hlt">glaciers</span> in Alaska. Evidence derived from ASTER and many other satellite and ground-based measurements suggests that only a few dozen Alaskan <span class="hlt">glaciers</span> are advancing. The overwhelming majority of them are retreating. This ASTER image was acquired on June 8, 2001. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next six years to map and monitor the changing surface of our planet. http://photojournal.jpl.nasa.gov/catalog/PIA03475</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28315057','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28315057"><span>Changes in precipitating snow chemistry with seasonality in the remote Laohugou <span class="hlt">glacier</span> <span class="hlt">basin</span>, western Qilian Mountains.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dong, Zhiwen; Qin, Dahe; Qin, Xiang; Cui, Jianyong; Kang, Shichang</p> <p>2017-04-01</p> <p>Trace elements in the atmosphere could provide information about regional atmospheric pollution. This study presented a whole year of precipitation observation data regarding the concentrations of trace metals (e.g., Cr, Ni, Cu, Mn, Cd, Mo, Pb, Sb, Ti, and Zn), and a TEM-EDX (transmission electron microscope-energy dispersive X-ray spectrometer) analysis from June 2014 to September 2015 at a remote alpine <span class="hlt">glacier</span> <span class="hlt">basin</span> in Northwest China, the Laohugou (LHG) <span class="hlt">basin</span> (4200 m a.s.l.), to determine the regional scale of atmospheric conditions and chemical processing in the free troposphere in the region. The results of the concentrations of trace metals showed that, although the concentrations generally were lower compared with that of surrounding rural areas (and cities), they showed an obviously higher concentration and higher EFs in winter (DJF) and a relatively lower concentration and lower EFs in summer (JJA) and autumn (SON), implying clearly enhanced winter pollution of the regional atmosphere in Northwest China. The TEM observed residue in precipitation that was mainly composed of types of dust, salt-dust, BC-fly ash-soot, and organic particles in precipitation, which also showed remarked seasonal change, showing an especially high ratio of BC-soot-fly ash particles in winter precipitation compared with that of other seasons (while organic particles were higher in the summer), indicating significant increased anthropogenic particles in the winter atmosphere. The source of increased winter anthropogenic pollutants mainly originated from emissions from coal combustion, e.g., the regional winter heating supply for residents and cement factories in urban and rural regions of Northwest China. Moderate Resolution Imaging Spectroradiometer (MODIS) atmospheric optical depth (AOD) also showed a significant influence of regional atmospheric pollutant emissions over the region in winter. In total, this work indicated that the atmospheric environment in western Qilian</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AIPC.1953n0018A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AIPC.1953n0018A"><span>Thermal <span class="hlt">non</span>-equilibrium in porous medium <span class="hlt">adjacent</span> to vertical plate: ANN approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ahmed, N. J. Salman; Ahamed, K. S. Nazim; Al-Rashed, Abdullah A. A. A.; Kamangar, Sarfaraz; Athani, Abdulgaphur</p> <p>2018-05-01</p> <p>Thermal <span class="hlt">non</span>-equilibrium in porous medium is a condition that refers to temperature discrepancy in solid matrix and fluid of porous medium. This type of flow is complex flow requiring complex set of partial differential equations that govern the flow behavior. The current work is undertaken to predict the thermal <span class="hlt">non</span>-equilibrium behavior of porous medium <span class="hlt">adjacent</span> to vertical plate using artificial neural network. A set of neurons in 3 layers are trained to predict the heat transfer characteristics. It is found that the thermal <span class="hlt">non</span>-equilibrium heat transfer behavior in terms of Nusselt number of fluid as well as solid phase can be predicted accurately by using well-trained neural network.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29027048','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29027048"><span>Export fluxes of geochemical solutes in the meltwater stream of Sutri Dhaka <span class="hlt">Glacier</span>, Chandra <span class="hlt">basin</span>, Western Himalaya.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Singh, Ajit T; Laluraj, C M; Sharma, Parmanand; Patel, Lavkush K; Thamban, Meloth</p> <p>2017-10-12</p> <p>The hydrochemistry of meltwater from the Sutri Dhaka <span class="hlt">Glacier</span>, Western Himalaya, has been studied to understand the influence of the factors controlling the weathering processes of the <span class="hlt">glaciers</span> during the peak ablation period. The high solar irradiance prompted intense melting, which has raised the stream flow of the <span class="hlt">glacier</span>. The meltwater has been observed as slightly alkaline (mean pH 8.2) and contains the major anions (HCO 3 -  > SO 4 2-  > NO 3 -  > Cl - ) and cations (Ca 2+  > Mg 2+  > K +  > Na +  > NH 4 + ) with Ca 2+ (78.5%) and HCO 3 - (74.5%) as the dominant species. The piper diagram indicates the category of stream meltwater as Ca 2+ -HCO 3 - type. In addition, it is evident from the Gibbs diagram that the interaction between the meltwater and bedrock controls the ionic concentrations of the glacial meltwater. The high ratio value (~ 0.75) of HCO 3 - /(HCO 3 -  + SO 4 2- ) indicates that the carbonate weathering is dominant. Fe and Al followed by Mn, Sr, and Ti are the most dominant trace elements present in the meltwater. The significant negative correlation exhibited by the major ions and Sr with the discharge is recommended for the enrichment of these solutes during the lean discharge periods. However, the insignificant correlation of Fe, Al, Mn, and Ti with discharge suggests their physicochemical control. The principal component analysis (PCA) carried has highlighted three dominant composites, i.e., the water-rock interaction, atmospheric dust inputs, and physicochemical changes in the meltwater. Hence, the present study elucidates the export of geochemical solutes from Sutri Dhaka <span class="hlt">Glacier</span> and factors governing the water chemistry, which helps in the better understanding of hydrochemical processes of the Himalayan <span class="hlt">glaciers</span> and substantial improvement of our understanding about the glacio-hydrological environments and their response in the scenario of global warming.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016HydJ...24..757R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016HydJ...24..757R"><span>Quantity and location of groundwater recharge in the Sacramento Mountains, south-central New Mexico (USA), and their relation to the <span class="hlt">adjacent</span> Roswell Artesian <span class="hlt">Basin</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rawling, Geoffrey C.; Newton, B. Talon</p> <p>2016-06-01</p> <p>The Sacramento Mountains and the <span class="hlt">adjacent</span> Roswell Artesian <span class="hlt">Basin</span>, in south-central New Mexico (USA), comprise a regional hydrologic system, wherein recharge in the mountains ultimately supplies water to the confined <span class="hlt">basin</span> aquifer. Geologic, hydrologic, geochemical, and climatologic data were used to delineate the area of recharge in the southern Sacramento Mountains. The water-table fluctuation and chloride mass-balance methods were used to quantify recharge over a range of spatial and temporal scales. Extrapolation of the quantitative recharge estimates to the entire Sacramento Mountains region allowed comparison with previous recharge estimates for the northern Sacramento Mountains and the Roswell Artesian <span class="hlt">Basin</span>. Recharge in the Sacramento Mountains is estimated to range from 159.86 × 106 to 209.42 × 106 m3/year. Both the location of recharge and range in estimates is consistent with previous work that suggests that ~75 % of the recharge to the confined aquifer in the Roswell Artesian <span class="hlt">Basin</span> has moved downgradient through the Yeso Formation from distal recharge areas in the Sacramento Mountains. A smaller recharge component is derived from infiltration of streamflow beneath the major drainages that cross the Pecos Slope, but in the southern Sacramento Mountains much of this water is ultimately derived from spring discharge. Direct recharge across the Pecos Slope between the mountains and the confined <span class="hlt">basin</span> aquifer is much smaller than either of the other two components.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70017394','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70017394"><span>Geologic and hydrologic hazards in <span class="hlt">glacierized</span> <span class="hlt">basins</span> in North America resulting from 19th and 20th century global warming</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>O'Connor, J. E.; Costa, J.E.</p> <p>1993-01-01</p> <p>Alpine <span class="hlt">glacier</span> retreat resulting from global warming since the close of the Little Ice Age in the 19th and 20th centuries has increased the risk and incidence of some geologic and hydrologic hazards in mountainous alpine regions of North America. Abundant loose debris in recently deglaciated areas at the toe of alpine <span class="hlt">glaciers</span> provides a ready source of sediment during rainstorms or outburst floods. This sediment can cause debris flows and sedimentation problems in downstream areas. Moraines built during the Little Ice Age can trap and store large volumes of water. These natural dams have no controlled outlets and can fail without warning. Many <span class="hlt">glacier</span>-dammed lakes have grown in size, while ice dams have shrunk, resulting in greater risks of ice-dam failure. The retreat and thinning of <span class="hlt">glacier</span> ice has left oversteepened, unstable valley walls and has led to increased incidence of rock and debris avalanches. ?? 1993 Kluwer Academic Publishers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.1559G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.1559G"><span>Morphological evidence and direct estimates of rapid melting beneath Totten <span class="hlt">Glacier</span> Ice Shelf, East Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Greenbaum, Jamin; Schroeder, Dustin; Grima, Cyril; Habbal, Feras; Dow, Christine; Roberts, Jason; Gwyther, David; van Ommen, Tas; Siegert, Martin; Blankenship, Donald</p> <p>2017-04-01</p> <p>Totten <span class="hlt">Glacier</span> drains at least 3.5 meters of eustatic sea level potential from marine-based ice in the Aurora Subglacial <span class="hlt">Basin</span> (ASB) in East Antarctica, more than the combined total of all <span class="hlt">glaciers</span> in West Antarctica. Totten <span class="hlt">Glacier</span> has been the most rapidly thinning <span class="hlt">glacier</span> in East Antarctica since satellite altimetry time series began and the nature of the thinning suggests that it is driven by enhanced basal melting due to ocean processes. While grounded ice thinning rates have been steady, recent work has shown that Totten's floating ice shelf may not have the same thinning behavior; as a result, it is critical to observe ice shelf and cavity boundary conditions and basal processes to understand this apparent discrepancy. Warm Modified Circumpolar Deep Water (MCDW), which has been linked to <span class="hlt">glacier</span> retreat in West Antarctica, has been observed in summer and winter on the nearby Sabrina Coast continental shelf and deep depressions in the seafloor provide access for MCDW to reach the ice shelf cavity. Given its northern latitude, numerical ice sheet modeling indicates that Totten <span class="hlt">Glacier</span> may be prone to retreat caused by hydrofracture in a warming climate, so it is important to understand how intruding MCDW is affecting thinning of Totten <span class="hlt">Glacier</span>'s ice shelf. Here we use post-processed, focused airborne radar observations of the Totten <span class="hlt">Glacier</span> Ice Shelf to delineate multi-km wide basal channels and flat basal terraces associated with high basal reflectivity and specularity (flatness) anomalies and correspondingly large ice surface depressions that indicate active basal melting. Using a simple temperature-attenuation model, and basal roughness corrections, we present basal melt rates associated with the radar reflection and specularity anomalies and compare them to those derived from numerical ocean circulation modeling and an ice flow divergence calculation. Sub-ice shelf ocean circulation modeling and under-ice robotic observations of Pine Island <span class="hlt">Glacier</span> Ice</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-GSFC_20171208_Archive_e002161.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-GSFC_20171208_Archive_e002161.html"><span>Icefall, Lambert <span class="hlt">Glacier</span>, Antarctica</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-08</p> <p>Image taken 12/2/2000: The Lambert <span class="hlt">Glacier</span> in Antarctica, is the world's largest <span class="hlt">glacier</span>. The focal point of this image is an icefall that feeds into the Lambert <span class="hlt">glacier</span> from the vast ice sheet covering the polar plateau. Ice flows like water, albeit much more slowly. Cracks can be seen in this icefall as it bends and twists on its slow-motion descent 1300 feet (400 meters) to the <span class="hlt">glacier</span> below. This Icefall can be found on Landsat 7 WRS Path 42 Row 133/134/135, center: -70.92, 69.15. To learn more about the Landsat satellite go to: landsat.gsfc.nasa.gov/</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B54B..05H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B54B..05H"><span>Differences in dissolved organic matter lability between alpine <span class="hlt">glaciers</span> and alpine rock <span class="hlt">glaciers</span> of the American West</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hall, E.; Fegel, T. S., II; Baron, J.; Boot, C. M.</p> <p>2015-12-01</p> <p>While alpine <span class="hlt">glaciers</span> in montane regions represent the largest flux of dissolved organic matter (DOM) from global ice melt no research has examined the bioavailability of DOM melted out of glacial ice in the western continental United States. Furthermore, rock <span class="hlt">glaciers</span> are an order of magnitude more abundant than ice <span class="hlt">glaciers</span> in U.S., yet are not included in budgets for perennial ice carbon stores. Our research aims to understand differences in the bioavailability of carbon from ice <span class="hlt">glaciers</span> and rock <span class="hlt">glaciers</span> along the Central Rocky Mountains of Colorado. Identical microbial communities were fed standardized amounts of DOM from four different ice <span class="hlt">glacier</span>-rock <span class="hlt">glaciers</span> pairs. Using laboratory incubations, paired with mass spectrometry based metabolomics and 16S gene sequencing; we were able to examine functional definitions of DOM lability in glacial ice. We hypothesized that even though DOM quantities are similar in the outputs of both glacial types in our study area, ice glacial DOM would be more bioavailable than DOM from rock <span class="hlt">glaciers</span> due to higher proportions of byproducts from microbial metabolism than rock <span class="hlt">glacier</span> DOM, which has higher amounts of "recalcitrant" plant material. Our results show that DOM from ice <span class="hlt">glaciers</span> is more labile than DOM from geologically and geographically similar paired rock <span class="hlt">glaciers</span>. Ice <span class="hlt">glacier</span> DOM represents an important pool of labile carbon to headwater ecosystems of the Rocky Mountains. Metabolomic analysis shows numerous compounds from varying metabolite pathways, including byproducts of nitrification before and after incubation, meaning that, similar to large maritime <span class="hlt">glaciers</span> in Alaska and Europe, subglacial environments in the mountain ranges of the United States are hotspots for biological activity and processing of organic carbon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JARS...10c6017W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JARS...10c6017W"><span>Climate-driven changes in grassland vegetation, snow cover, and lake water of the Qinghai Lake <span class="hlt">basin</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Xuelu; Liang, Tiangang; Xie, Hongjie; Huang, Xiaodong; Lin, Huilong</p> <p>2016-07-01</p> <p>Qinghai Lake <span class="hlt">basin</span> and the lake have undergone significant changes in recent decades. We examine MODIS-derived grassland vegetation and snow cover of the Qinghai Lake <span class="hlt">basin</span> and their relations with climate parameters during 2001 to 2010. Results show: (1) temperature and precipitation of the Qinghai Lake <span class="hlt">basin</span> increased while evaporation decreased; (2) most of the grassland areas improved due to increased temperature and growing season precipitation; (3) weak relations between snow cover and precipitation/vegetation; (4) a significantly negative correlation between lake area and temperature (r=-0.9, p<0.05) and (5) a positive relation between lake level (lake-level difference) and temperature (precipitation). Compared with Namco Lake (located in the inner Tibetan Plateau) where the primary water source of lake level increases was the accelerated melt of <span class="hlt">glacier</span>/perennial snow cover in the lake <span class="hlt">basin</span>, for the Qinghai Lake, however, it was the increased precipitation. Increased precipitation explained the improvement of vegetation cover in the Qinghai Lake <span class="hlt">basin</span>, while accelerated melt of <span class="hlt">glacier</span>/perennial snow cover was responsible for the degradation of vegetation cover in Namco Lake <span class="hlt">basin</span>. These results suggest different responses to the similar warming climate: improved (degraded) ecological condition and productive capacity of the Qinghai Lake <span class="hlt">basin</span> (Namco Lake <span class="hlt">basin</span>).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C53B1026P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C53B1026P"><span>Uncertainty in Estimates of Net Seasonal Snow Accumulation on <span class="hlt">Glaciers</span> from In Situ Measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pulwicki, A.; Flowers, G. E.; Radic, V.</p> <p>2017-12-01</p> <p>Accurately estimating the net seasonal snow accumulation (or "winter balance") on <span class="hlt">glaciers</span> is central to assessing <span class="hlt">glacier</span> health and predicting <span class="hlt">glacier</span> runoff. However, measuring and modeling snow distribution is inherently difficult in mountainous terrain, resulting in high uncertainties in estimates of winter balance. Our work focuses on uncertainty attribution within the process of converting direct measurements of snow depth and density to estimates of winter balance. We collected more than 9000 direct measurements of snow depth across three <span class="hlt">glaciers</span> in the St. Elias Mountains, Yukon, Canada in May 2016. Linear regression (LR) and simple kriging (SK), combined with cross correlation and Bayesian model averaging, are used to interpolate estimates of snow water equivalent (SWE) from snow depth and density measurements. Snow distribution patterns are found to differ considerably between <span class="hlt">glaciers</span>, highlighting strong inter- and intra-<span class="hlt">basin</span> variability. Elevation is found to be the dominant control of the spatial distribution of SWE, but the relationship varies considerably between <span class="hlt">glaciers</span>. A simple parameterization of wind redistribution is also a small but statistically significant predictor of SWE. The SWE estimated for one study <span class="hlt">glacier</span> has a short range parameter (90 m) and both LR and SK estimate a winter balance of 0.6 m w.e. but are poor predictors of SWE at measurement locations. The other two <span class="hlt">glaciers</span> have longer SWE range parameters ( 450 m) and due to differences in extrapolation, SK estimates are more than 0.1 m w.e. (up to 40%) lower than LR estimates. By using a Monte Carlo method to quantify the effects of various sources of uncertainty, we find that the interpolation of estimated values of SWE is a larger source of uncertainty than the assignment of snow density or than the representation of the SWE value within a terrain model grid cell. For our study <span class="hlt">glaciers</span>, the total winter balance uncertainty ranges from 0.03 (8%) to 0.15 (54%) m w</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA11419.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA11419.html"><span>Byrd <span class="hlt">Glacier</span>, Antarctica</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2008-11-17</p> <p>Byrd <span class="hlt">Glacier</span> is a major <span class="hlt">glacier</span> in Antarctica; it drains an extensive area of the polar plateau and flows eastward between the Britannia Range and the Churchill Mountains to discharge into the Ross Ice Shelf. This image is from NASA Terra satellite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/5175178-columbia-glacier-disintegration-underway','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5175178-columbia-glacier-disintegration-underway"><span>Columbia <span class="hlt">Glacier</span> in 1984: disintegration underway</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Meier, M.F.; Rasmussen, L.A.; Miller, D.S.</p> <p>1985-01-01</p> <p>Columbia <span class="hlt">Glacier</span> is a large, iceberg-calving <span class="hlt">glacier</span> near Valdez, Alaska. The terminus of this <span class="hlt">glacier</span> was relatively stable from the time of the first scientific studies in 1899 until 1978. During this period the <span class="hlt">glacier</span> terminated partly on Heather Island and partly on a submerged moraine shoal. In December, 1978, the <span class="hlt">glacier</span> terminus retreated from Heather Island, and retreat has accelerated each year since then, except during a period of anomalously low calving in 1980. Although the <span class="hlt">glacier</span> has not terminated on Heather Island since 1978, a portion of the terminus remained on the crest of the moraine shoal untilmore » the fall of 1983. By December 8, 1983, that feature had receded more than 300 m from the crest of the shoal, and by December 14, 1984, had disappeared completely, leaving most of the terminus more than 2000 meters behind the crest of the shoal. Recession of the <span class="hlt">glacier</span> from the shoal has placed the terminus in deeper water, although the <span class="hlt">glacier</span> does not float. The active calving face of the <span class="hlt">glacier</span> now terminates in seawater that is about 300 meters deep at the <span class="hlt">glacier</span> centerline. Rapid calving appears to be associated with buoyancy effects due to deep water at the terminus and subglacial runoff. 12 refs., 10 figs.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.2450Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.2450Y"><span>GRACE captures <span class="hlt">basin</span> mass dynamic changes in China based on a multi-<span class="hlt">basin</span> inversion method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yi, Shuang; Wang, Qiuyu; Sun, Wenke</p> <p>2016-04-01</p> <p>Complex landform, miscellaneous climate and enormous population have enriched China with geophysical phenomena ranging from water depletion in the underground to <span class="hlt">glaciers</span> retreat on the high mountains and have aroused large scientific interests. This paper, utilizing gravity observations 2003-2014 from the Gravity Recovery and Climate Experiment (GRACE), intends to make a comprehensive estimation of mass status in 16 drainage <span class="hlt">basins</span> in the whole region. We proposed a multi-<span class="hlt">basin</span> inversion method, which is featured by resistance to the stripe noise and ability to alleviate signal attenuation due to truncation and smoothing of GRACE data. The results show both positive and negative trends: there is a tremendous mass accumulation spreading from the Tibetan plateau (12.2 ± 0.6 Gt/yr) to the Yangtze River (7.6 ± 1.3 Gt/yr), and further to the southeast coastal areas, which is suggested to involve an increase in the ground water storage, lake and reservoir water volume and likely materials flowed in by tectonic process; a mass loss is occurring in Huang-Huai-Hai-Liao River <span class="hlt">Basin</span> (-10.5 ± 0.8 Gt/yr), as well as the Brahmaputra-Nujiang-Lancang River <span class="hlt">Basin</span> (-15.0 ± 0.9 Gt/yr) and Tienshan Mountain (-4.1 ± 0.3 Gt/yr), which is a result of groundwater pumping and <span class="hlt">glacier</span> melting. The groundwater depletion area is well consistent with the distribution of land subsidence in North China. In the end, we find intensified precipitation can alter the local water supply and GRACE is proficient to capture this dynamics, which could be instructive for the South-to-North Water Diversion - one China's giant hydrologic project.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1714078M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1714078M"><span>Annual and seasonal mass balances of Chhota Shigri <span class="hlt">Glacier</span> (benchmark <span class="hlt">glacier</span>, Western Himalaya), India</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mandal, Arindan; Ramanathan, Alagappan; Farooq Azam, Mohd; Wagnon, Patrick; Vincent, Christian; Linda, Anurag; Sharma, Parmanand; Angchuk, Thupstan; Bahadur Singh, Virendra; Pottakkal, Jose George; Kumar, Naveen; Soheb, Mohd</p> <p>2015-04-01</p> <p>Several studies on Himalayan <span class="hlt">glaciers</span> have been recently initiated as they are of particular interest in terms of future water supply, regional climate change and sea-level rise. In 2002, a long-term monitoring program was initiated on Chhota Shigri <span class="hlt">Glacier</span> (15.7 square km, 9 km long, 6263-4050 m a.s.l.) located in Lahaul and Spiti Valley, Himachal Pradesh, India. This <span class="hlt">glacier</span> lies in the monsoon-arid transition zone (western Himalaya) and is a representative <span class="hlt">glacier</span> in Lahaul and Spiti Valley. While annual mass balances have been measured continuously since 2002 using the glaciological method, seasonal scale observations began in 2009. The annual and seasonal mass balances were then analyzed along with meteorological conditions in order to understand the role of winter and summer balances on annual <span class="hlt">glacier</span>-wide mass balance of Chhota Shigri <span class="hlt">glacier</span>. During the period 2002-2013, the <span class="hlt">glacier</span> experienced a negative <span class="hlt">glacier</span>-wide mass balance of -0.59±0.40 m w.e. a-1 with a cumulative glaciological mass balance of -6.45 m w.e. Annual <span class="hlt">glacier</span>-wide mass balances were negative except for four years (2004/05, 2008/09, 2009/10 and 2010/11) where it was generally close to balanced conditions. Equilibrium line altitude (ELA) for steady state condition is calculated as 4950 m a.s.l. corresponding to an accumulation area ratio (AAR) of 62% using annual <span class="hlt">glacier</span>-wide mass balance, ELA and AAR data between 2002 and 2013. The winter <span class="hlt">glacier</span>-wide mass balance between 2009 and 2013 ranges from a maximum value of 1.38 m w.e. in 2009/10 to a minimum value of 0.89 in 2012/13 year whereas the summer <span class="hlt">glacier</span>-wide mass balance varies from the highest value of -0.95 m w.e. in 2010/11 to the lowest value of -1.72 m w.e. in 2011/12 year. The mean vertical mass balance gradient between 2002 and 2013 was 0.66 m w.e. (100 m)-1 quite similar to Alps, Nepalese Himalayas etc. Over debris covered area, the gradients are highly variable with a negative mean value of -2.15 m w.e. (100 m)-1 over 2002</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C51D..08S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C51D..08S"><span>High-resolution DEMs for High-mountain Asia: A systematic, region-wide assessment of geodetic <span class="hlt">glacier</span> mass balance and dynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shean, D. E.; Arendt, A. A.; Osmanoglu, B.; Montesano, P.</p> <p>2017-12-01</p> <p>High Mountain Asia (HMA) constitutes the largest <span class="hlt">glacierized</span> region outside of the Earth's polar regions. Although available observations are limited, long-term records indicate sustained regional <span class="hlt">glacier</span> mass loss since 1850, with increased loss in recent decades. Recent satellite data (e.g., GRACE, ICESat-1) show spatially variable <span class="hlt">glacier</span> mass balance, with significant mass loss in the Himalaya and Hindu Kush and slight mass gain in the Karakoram. We generated 4000 high-resolution digital elevation models (DEMs) from sub-meter commercial stereo imagery (DigitalGlobe WorldView/GeoEye) acquired over <span class="hlt">glaciers</span> in High-mountain Asia from 2002-present (mostly 2013-present). We produced a regional 8-m DEM mosaic for 2015 and estimated 15-year geodetic mass balance for 40000 <span class="hlt">glaciers</span> larger than 0.1 km2. We are combining with other regional DEM sources to systematically document the spatiotemporal evolution of <span class="hlt">glacier</span> mass balance for the entire HMA region. We also generated monthly to interannual DEM and velocity time series for high-priority sites distributed across the region, with >15-20 DEMs available for some locations from 2010-present. These records document <span class="hlt">glacier</span> dynamics, seasonal snow accumulation/redistribution, and processes that affect <span class="hlt">glacier</span> mass balance (e.g., ice-cliff retreat, debris cover evolution). These efforts will provide <span class="hlt">basin</span>-scale assessments of snow/ice melt runoff contributions for model cal/val and downstream water resources applications. We will continue processing all archived and newly available commercial stereo imagery for HMA, and will release all DEMs through the HiMAT DAAC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C13B0432L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C13B0432L"><span>Middle to late Holocene fluctuations of the Vindue <span class="hlt">glacier</span>, an outlet <span class="hlt">glacier</span> of the Greenland Ice Sheet, central East Greenland.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Levy, L.; Hammer, S. K.; Kelly, M. A.; Lowell, T. V.; Hall, B. L.; Howley, J. A.; Wilcox, P.; Medford, A.</p> <p>2014-12-01</p> <p>The margins of the Greenland Ice Sheet are currently responding to present-day climate changes. Determining how the ice sheet margins have responded to past climate changes provides a means to understand how they may respond in the future. Here we present a multi-proxy record used to reconstruct the Holocene fluctuations of the Vindue <span class="hlt">glacier</span>, an ice sheet outlet <span class="hlt">glacier</span> in eastern Greenland. Lake sediment cores from Qiviut lake (informal name), located ~0.75 km from the present-day Vindue <span class="hlt">glacier</span> margin contain a sharp transition from medium sand/coarse silt to laminated gyttja just prior to 6,340±130 cal yr BP. We interpret this transition to indicate a time when the Vindue <span class="hlt">glacier</span> retreated sufficiently to cease glacial sedimentation into the lake <span class="hlt">basin</span>. Above this contact the core contains laminated gyttja with prominent, ~0.5 cm thick, silt layers. 10Be ages of boulders on bedrock located between Qiviut lake and the present-day ice margin date to 6.81 ± 0.67 ka (n = 3), indicating the time of deglaciation. These ages also agree well with the radiocarbon age of the silt-gyttja transition in Qiviut lake cores. 10Be ages on boulders on bedrock located more proximal to the ice margin (~0.5 km) yield ages of 2.67 ± 0.18 ka (n = 2). These ages indicate either the continued recession of the ice margin during the late Holocene or an advance at this time. Boulders on the historical moraines show that ice retreated from the moraine by AD 1620 ± 20 yrs (n = 2). These results are in contrast with some areas of the western margin of the ice sheet where 10Be ages indicate that the ice sheet was behind its Historical limit from the middle Holocene (~6-7 ka) to Historical time. This may indicate that the eastern margin may have responded to late Holocene cooling more sensitively or that the advance associated with the Historical moraines overran any evidence of late Holocene fluctuations along the western margin of the ice sheet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMPP14B..01G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMPP14B..01G"><span>Low latitude ice core evidence for dust deposition on high altitude <span class="hlt">glaciers</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gabrielli, P.; Thompson, L. G.</p> <p>2017-12-01</p> <p>Polar ice cores from Antarctica and Greenland have provided a wealth of information on dust emission, transport and deposition over glacial to interglacial timescales. These ice cores mainly entrap dust transported long distances from source areas such as Asia for Greenland and South America for Antarctica. Thus, these dust records provide paleo-information about the environmental conditions at the source and the strength/pathways of atmospheric circulation at continental scales. Ice cores have also been extracted from high altitude <span class="hlt">glaciers</span> in the mid- and low-latitudes and provide dust records generally extending back several centuries and in a few cases back to the last glacial period. For these <span class="hlt">glaciers</span> the potential sources of dust emission include areas that are close or <span class="hlt">adjacent</span> to the drilling site which facilitates the potential for a strong imprinting of local dust in the records. In addition, only a few high altitude <span class="hlt">glaciers</span> allow the reconstruction of past snow accumulation and hence the expression of the dust records in terms of fluxes. Due to their extreme elevation, a few of these high altitude ice cores offer dust histories with the potential to record environmental conditions at remote sources. Dust records (in terms of dust concentration/size, crustal trace elements and terrigenous cations) from Africa, the European Alps, South America and the Himalayas are examined over the last millennium. The interplay of the seasonal atmospheric circulation (e.g. westerlies, monsoons and vertical convection) is shown to play a major role in determining the intensity and origin of dust fallout to the high altitude <span class="hlt">glaciers</span> around the world.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.C11E..01R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.C11E..01R"><span>GLIMS <span class="hlt">Glacier</span> Database: Status and Challenges</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raup, B. H.; Racoviteanu, A.; Khalsa, S. S.; Armstrong, R.</p> <p>2008-12-01</p> <p>GLIMS (Global Land Ice Measurements from Space) is an international initiative to map the world's <span class="hlt">glaciers</span> and to build a GIS database that is usable via the World Wide Web. The GLIMS programme includes 70 institutions, and 25 Regional Centers (RCs), who analyze satellite imagery to map <span class="hlt">glaciers</span> in their regions of expertise. The analysis results are collected at the National Snow and Ice Data Center (NSIDC) and ingested into the GLIMS <span class="hlt">Glacier</span> Database. The database contains approximately 80 000 <span class="hlt">glacier</span> outlines, half the estimated total on Earth. In addition, the database contains metadata on approximately 200 000 ASTER images acquired over <span class="hlt">glacierized</span> terrain. <span class="hlt">Glacier</span> data and the ASTER metadata can be viewed and searched via interactive maps at http://glims.org/. As <span class="hlt">glacier</span> mapping with GLIMS has progressed, various hurdles have arisen that have required solutions. For example, the GLIMS community has formulated definitions for how to delineate <span class="hlt">glaciers</span> with different complicated morphologies and how to deal with debris cover. Experiments have been carried out to assess the consistency of the database, and protocols have been defined for the RCs to follow in their mapping. Hurdles still remain. In June 2008, a workshop was convened in Boulder, Colorado to address issues such as mapping debris-covered <span class="hlt">glaciers</span>, mapping ice divides, and performing change analysis using two different <span class="hlt">glacier</span> inventories. This contribution summarizes the status of the GLIMS <span class="hlt">Glacier</span> Database and steps taken to ensure high data quality.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1917500F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1917500F"><span>Elevation and mass change of the Echaurren Norte <span class="hlt">Glacier</span> (Central Andes, Chile) from 1955 to 2015.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Farías, David; Vivero, Sebastián; Casassa, Gino; Seehaus, Thorsten; Braun, Matthias H.</p> <p>2017-04-01</p> <p>The Echaurren Norte <span class="hlt">Glacier</span> (33°34'S 70°07'W) is a small mountain <span class="hlt">glacier</span> located at the upper Maipo <span class="hlt">basin</span>, approximately 80 km to Santiago de Chile. The <span class="hlt">glacier</span> has the longest surface mass balance record in South America (1975 to 2016). The measurements are carried out by DGA (water directory of Chile) using the direct glaciological method. The surface mass balance show continuous negative values, but exceptional positive mass balances were identified during ENSO periods. The aim of our study is complement the in-situ observations on Echaurren Norte <span class="hlt">Glacier</span> with the geodetic mass balance measurements for the period 1955 to 2015. Our database comprises digital elevation models (DEM) from historical cartography based on aerial photographs (1955), SRTM (2000) and Lidar data. In addition, we mapped changes in <span class="hlt">glacier</span> extent using aerial photography and multi-mission satellite data. TanDEM-X (2012-2015) and SRTM data will be used to investigate surrounding <span class="hlt">glaciers</span> that have not such extensive and detailed coverage as Echaurren Norte <span class="hlt">Glacier</span>. The aerial photographs from 1955 were scanned from the original negative using a photogrammetric scanner and processed on a digital photogrammetric workstation (DPW) and georeferenced with the aid of GCPs derived from the Lidar dataset. The TanDEM-X data was processed using differential interferometry using SRTM C-band DEM as reference. Differences resulting from X- and C-band penetration are considered comparing X- and C-band SRTM data. All DEMs were laterally and vertically co-registered to each other. Error assessment was done over stable ground. Our preliminary results indicate an elevation change of -42.2 m ± 4 m (1955-2015) for Echaurren Norte <span class="hlt">Glacier</span>. The estimated averaged annual mass balance is -0.59 m water equivalent for the period 1955-2015 using a density of 0.85 kg/cm3 for volume to mass conversion. Significant changes of the surface cover were identified, with a considerable increase of the debris cover, in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70035965','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70035965"><span>Quantifying periglacial erosion: Insights on a glacial sediment budget, Matanuska <span class="hlt">Glacier</span>, Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>O'Farrell, C. R.; Heimsath, A.M.; Lawson, D.E.; Jorgensen, L.M.; Evenson, E.B.; Larson, G.; Denner, J.</p> <p>2009-01-01</p> <p>Glacial erosion rates are estimated to be among the highest in the world. Few studies have attempted, however, to quantify the flux of sediment from the periglacial landscape to a <span class="hlt">glacier</span>. Here, erosion rates from the nonglacial landscape above the Matanuska <span class="hlt">Glacier</span>, Alaska are presented and compare with an 8-yr record of proglacial suspended sediment yield. <span class="hlt">Non</span>-glacial lowering rates range from 1??8 ?? 0??5 mm yr-1 to 8??5 ?? 3??4 mm yr-1 from estimates of rock fall and debris-flow fan volumes. An average erosion rate of 0??08 ?? 0??04 mm yr-1 from eight convex-up ridge crests was determined using in situ produced cosmogenic 10Be. Extrapolating these rates, based on landscape morphometry, to the Matanuska <span class="hlt">basin</span> (58% ice-cover), it was found that nonglacial processes account for an annual sediment flux of 2??3 ?? 1??0 ?? 106 t. Suspended sediment data for 8 years and an assumed bedload to estimate the annual sediment yield at the Matanuska terminus to be 2??9 ?? 1??0 ?? 106 t, corresponding to an erosion rate of 1??8 ?? 0??6 mm yr-1: nonglacial sources therefore account for 80 ?? 45% of the proglacial yield. A similar set of analyses were used for a small tributary sub-<span class="hlt">basin</span> (32% ice-cover) to determine an erosion rate of 12??1 ?? 6??9 mm yr-1, based on proglacial sediment yield, with the nonglacial sediment flux equal to 10 ?? 7% of the proglacial yield. It is suggested that erosion rates by nonglacial processes are similar to inferred subglacial rates, such that the ice-free regions of a glaciated landscape contribute significantly to the glacial sediment budget. The similar magnitude of nonglacial and glacial rates implies that partially glaciated landscapes will respond rapidly to changes in climate and base level through a rapid nonglacial response to glacially driven incision. ?? 2009 John Wiley & Sons, Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.6593N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.6593N"><span>The 24 July 2008 outburst flood of Zyndan <span class="hlt">glacier</span> lake, Ysyk-Köl region, Kyrgyzstan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Narama, C.; Duishonakonov, M.; Kääb, A.; Abdrakhmatov, K.</p> <p>2009-04-01</p> <p>On 24 July 2008, a glacial lake outburst flood (GLOF) occurred in the Zyndan River, the Ysyk-Köl region, Kyrgyzstan. The flood killed three people and many livestock (horse, sheep, fish), and caused heavy damage destroying a bridge, road, two homes, and crops of agriculture fields. We researched the damege after two days of the GLOF. Using kinematic GPS we measured the decrease of the <span class="hlt">glacier</span> lake area, and the according drop of the water level through the outburst. <span class="hlt">Glacier</span> lake area of about 0.03 km2 reduced after the collapse, more than 400,000 m3 of water were discharged. While the initial flood discharge was relatively small, it increased substantially and was carrying large boulders after 30 minutes. When spreading further downstream, the dirty waters trapped eight people on islands between the stream branches. The flood discharge continued to rise until midnight and began to decrease again around 3 AM the next morning. The lake at 3771 m asl is located in front of the west Zyndan <span class="hlt">glacier</span> at the head of the Zyndan River <span class="hlt">basin</span>. The <span class="hlt">glacier</span> lake had developed rapidly due to <span class="hlt">glacier</span> shrinkage caused by recent atmospheric warming. Reasons for the outburst included melting of dead ice inside the moraine that dammed the lake. The villages downstream escaped heavy damage, because the main flood changed its direction, away from the water reservoir along the village and towards another river.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28733603','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28733603"><span>Sediment transport drives tidewater <span class="hlt">glacier</span> periodicity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brinkerhoff, Douglas; Truffer, Martin; Aschwanden, Andy</p> <p>2017-07-21</p> <p>Most of Earth's <span class="hlt">glaciers</span> are retreating, but some tidewater <span class="hlt">glaciers</span> are advancing despite increasing temperatures and contrary to their neighbors. This can be explained by the coupling of ice and sediment dynamics: a shoal forms at the <span class="hlt">glacier</span> terminus, reducing ice discharge and causing advance towards an unstable configuration followed by abrupt retreat, in a process known as the tidewater <span class="hlt">glacier</span> cycle. Here we use a numerical model calibrated with observations to show that interactions between ice flow, glacial erosion, and sediment transport drive these cycles, which occur independent of climate variations. Water availability controls cycle period and amplitude, and enhanced melt from future warming could trigger advance even in <span class="hlt">glaciers</span> that are steady or retreating, complicating interpretations of <span class="hlt">glacier</span> response to climate change. The resulting shifts in sediment and meltwater delivery from changes in <span class="hlt">glacier</span> configuration may impact interpretations of marine sediments, fjord geochemistry, and marine ecosystems.The reason some of the Earth's tidewater <span class="hlt">glaciers</span> are advancing despite increasing temperatures is not entirely clear. Here, using a numerical model that simulates both ice and sediment dynamics, the authors show that internal dynamics drive <span class="hlt">glacier</span> variability independent of climate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/sir/2010/5072/','USGSPUBS'); return false;" href="https://pubs.usgs.gov/sir/2010/5072/"><span>Geohydrology of the Aucilla-Suwannee-Ochlockonee River <span class="hlt">Basin</span>, south-central Georgia and <span class="hlt">adjacent</span> parts of Florida</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Torak, Lynn J.; Painter, Jaime A.; Peck, Michael F.</p> <p>2010-01-01</p> <p>Major streams and tributaries located in the Aucilla-Suwannee-Ochlockonee (ASO) River <span class="hlt">Basin</span> of south-central Georgia and <span class="hlt">adjacent</span> parts of Florida drain about 8,000 square miles of a layered sequence of clastic and carbonate sediments and carbonate Coastal Plain sediments consisting of the surficial aquifer system, upper semiconfining unit, Upper Floridan aquifer, and lower confining unit. Streams either flow directly on late-middle Eocene to Oligocene karst limestone or carve a dendritic drainage pattern into overlying Miocene to Holocene sand, silt, and clay, facilitating water exchange and hydraulic connection with geohydrologic units. Geologic structures operating in the ASO River <span class="hlt">Basin</span> through time control sedimentation and influence geohydrology and water exchange between geohydrologic units and surface water. More than 300 feet (ft) of clastic sediments overlie the Upper Floridan aquifer in the Gulf Trough-Apalachicola Embayment, a broad area extending from the southwest to the northeast through the center of the <span class="hlt">basin</span>. These clastic sediments limit hydraulic connection and water exchange between the Upper Floridan aquifer, the surficial aquifer system, and surface water. Accumulation of more than 350 ft of low-permeability sediments in the Southeast Georgia Embayment and Suwannee Strait hydraulically isolates the Upper Floridan aquifer from land-surface hydrologic processes in the Okefenokee <span class="hlt">Basin</span> physiographic district. Burial of limestone beneath thick clastic overburden in these areas virtually eliminates karst processes, resulting in low aquifer hydraulic conductivity and storage coefficient despite an aquifer thickness of more than 900 ft. Conversely, uplift and faulting associated with regional tectonics and the northern extension of the Peninsular Arch caused thinning and erosion of clastic sediments overlying the Upper Floridan aquifer southeast of the Gulf Trough-Apalachicola Embayment near the Florida-Georgia State line. Limestone dissolution in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1910602R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1910602R"><span>Recent Advances in the GLIMS <span class="hlt">Glacier</span> Database</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raup, Bruce; Cogley, Graham; Zemp, Michael; Glaus, Ladina</p> <p>2017-04-01</p> <p><span class="hlt">Glaciers</span> are shrinking almost without exception. <span class="hlt">Glacier</span> losses have impacts on local water availability and hazards, and contribute to sea level rise. To understand these impacts and the processes behind them, it is crucial to monitor <span class="hlt">glaciers</span> through time by mapping their areal extent, changes in volume, elevation distribution, snow lines, ice flow velocities, and changes to associated water bodies. The <span class="hlt">glacier</span> database of the Global Land Ice Measurements from Space (GLIMS) initiative is the only multi-temporal <span class="hlt">glacier</span> database capable of tracking all these <span class="hlt">glacier</span> measurements and providing them to the scientific community and broader public. Here we present recent results in 1) expansion of the geographic and temporal coverage of the GLIMS <span class="hlt">Glacier</span> Database by drawing on the Randolph <span class="hlt">Glacier</span> Inventory (RGI) and other new data sets; 2) improved tools for visualizing and downloading GLIMS data in a choice of formats and data models; and 3) a new data model for handling multiple <span class="hlt">glacier</span> records through time while avoiding double-counting of <span class="hlt">glacier</span> number or area. The result of this work is a more complete <span class="hlt">glacier</span> data repository that shows not only the current state of <span class="hlt">glaciers</span> on Earth, but how they have changed in recent decades. The database is useful for tracking changes in water resources, hazards, and mass budgets of the world's <span class="hlt">glaciers</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/pp/1406c/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/pp/1406c/report.pdf"><span>Geochemistry of ground water in alluvial <span class="hlt">basins</span> of Arizona and <span class="hlt">adjacent</span> parts of Nevada, New Mexico, and California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Robertson, Frederick N.</p> <p>1991-01-01</p> <p>Chemical and isotope analyses of ground water from 28 <span class="hlt">basins</span> in the <span class="hlt">Basin</span> and Range physiographic province of Arizona and parts of <span class="hlt">adjacent</span> States were used to evaluate ground-water quality, determine processes that control ground-water chemistry, provide independent insight into the hydrologic flow system, and develop information transfer. The area is characterized by north- to northwest-trending mountains separated by alluvial <span class="hlt">basins</span> that form a regional topography of alternating mountains and valleys. On the basis of ground-water divides or zones of minimal <span class="hlt">basin</span> interconnection, the area was divided into 72 <span class="hlt">basins</span>, each representing an individual aquifer system. These systems are joined in a dendritic pattern and collectively constitute the major water resource in the region. Geochemical models were developed to identify reactions and mass transfer responsible for the chemical evolution of the ground water. On the basis of mineralogy and chemistry of the two major rock associations of the area, a felsic model and a mafic model were developed to illustrate geologic, climatic, and physiographic effects on ground-water chemistry. Two distinct hydrochemical processes were identified: (1) reactions of meteoric water with minerals and gases in recharge areas and (2) reactions of ground water as it moves down the hydraulic gradient. Reactions occurring in recharge and downgradient areas can be described by a 13-component system. Major reactions are the dissolution and precipitation of calcite and dolomite, the weathering of feldspars and ferromagnesian minerals, the formation of montmorillonite, iron oxyhydroxides, and probably silica, and, in some <span class="hlt">basins</span>, ion exchange. The geochemical modeling demonstrated that relatively few phases are required to derive the ground-water chemistry; 14 phases-12 mineral and 2 gas-consistently account for the chemical evolution in each <span class="hlt">basin</span>. The final phases were selected through analysis of X-ray diffraction and fluorescence data</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1914960S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1914960S"><span>Spatiotemporal tracer variability in <span class="hlt">glacier</span> melt and its influence on hydrograph separation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmieder, Jan; Marke, Thomas; Strasser, Ulrich</p> <p>2017-04-01</p> <p><span class="hlt">Glaciers</span> are important seasonal water contributors in many mountainous regions. Knowledge on the timing and amount of <span class="hlt">glacier</span> melt water is crucial for water resources management, especially in downstream regions where the water is needed (hydropower, drinking water) or where it represents a potential risk (drought, flood). This becomes even more relevant in a changing climate. Environmental tracers are a useful tool in the assessment of ice water resources, because they provide information about the sources, flow paths and traveling times of water contributing to streamflow at the catchment scale. Hydrometric and meteorological measurements combined with tracer analyses help to unravel streamflow composition and improve the understanding of hydroclimatological processes. Empirical studies on runoff composition are necessary to parameterize and validate hydrological models in a process-oriented manner, rather than comparing total measured and simulated runoff only. In the present study three approaches of hydrograph separation are compared to decide which sampling frequency is required to capture the spatiotemporal variability of <span class="hlt">glacier</span> melt, and to draw implications for future studies of streamflow partitioning. Therefore <span class="hlt">glacier</span> melt contributions to a proglacial stream at the sub-daily, daily, and seasonal scale were estimated using electrical conductivity and oxygen-18 as tracers. The field work was conducted during December 2015 and September 2016 in the glaciated (34%) high-elevation catchment of the Hochjochbach, a small sub-<span class="hlt">basin</span> (17 km2) of the Oetztaler Ache river in the Austrian Alps, ranging from 2400 to 3500 m a.s.l. in elevation. Hydroclimatological data was provided by an automatic weather station and a streamflow gauging station equipped with a pressure transducer. Water samples of streamflow, <span class="hlt">glacier</span> melt, and rain were collected throughout the winter period (December to March) and the ablation season (July to September). In the proposed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018NHESS..18.1055F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018NHESS..18.1055F"><span>Combination of UAV and terrestrial photogrammetry to assess rapid <span class="hlt">glacier</span> evolution and map <span class="hlt">glacier</span> hazards</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fugazza, Davide; Scaioni, Marco; Corti, Manuel; D'Agata, Carlo; Azzoni, Roberto Sergio; Cernuschi, Massimo; Smiraglia, Claudio; Diolaiuti, Guglielmina Adele</p> <p>2018-04-01</p> <p>Tourists and hikers visiting <span class="hlt">glaciers</span> all year round face hazards such as sudden terminus collapses, typical of such a dynamically evolving environment. In this study, we analyzed the potential of different survey techniques to analyze hazards of the Forni <span class="hlt">Glacier</span>, an important geosite located in Stelvio Park (Italian Alps). We carried out surveys in the 2016 ablation season and compared point clouds generated from an unmanned aerial vehicle (UAV) survey, close-range photogrammetry and terrestrial laser scanning (TLS). To investigate the evolution of <span class="hlt">glacier</span> hazards and evaluate the <span class="hlt">glacier</span> thinning rate, we also used UAV data collected in 2014 and a digital elevation model (DEM) created from an aerial photogrammetric survey of 2007. We found that the integration between terrestrial and UAV photogrammetry is ideal for mapping hazards related to the <span class="hlt">glacier</span> collapse, while TLS is affected by occlusions and is logistically complex in glacial terrain. Photogrammetric techniques can therefore replace TLS for <span class="hlt">glacier</span> studies and UAV-based DEMs hold potential for becoming a standard tool in the investigation of <span class="hlt">glacier</span> thickness changes. Based on our data sets, an increase in the size of collapses was found over the study period, and the <span class="hlt">glacier</span> thinning rates went from 4.55 ± 0.24 m a-1 between 2007 and 2014 to 5.20 ± 1.11 m a-1 between 2014 and 2016.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001909.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001909.html"><span>Gyldenlove <span class="hlt">Glacier</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2011-04-11</p> <p>On April 11, 2011, IceBridge finally got the clear weather necessary to fly over <span class="hlt">glaciers</span> in southeast Greenland. But with clear skies came winds of up to 70 knots, which made for a bumpy ride over the calving front of <span class="hlt">glaciers</span> like Gyldenlove. Operation IceBridge, now in its third year, makes annual campaigns in the Arctic and Antarctic where science flights monitor <span class="hlt">glaciers</span>, ice sheets and sea ice. Credit: NASA/GSFC/Michael Studinger To learn more about Ice Bridge go to: www.nasa.gov/mission_pages/icebridge/news/spr11/index.html NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015TCry....9.2215B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015TCry....9.2215B"><span>Brief communication: Getting Greenland's <span class="hlt">glaciers</span> right - a new data set of all official Greenlandic <span class="hlt">glacier</span> names</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bjørk, A. A.; Kruse, L. M.; Michaelsen, P. B.</p> <p>2015-12-01</p> <p>Place names in Greenland can be difficult to get right, as they are a mix of Greenlandic, Danish, and other foreign languages. In addition, orthographies have changed over time. With this new data set, we give the researcher working with Greenlandic <span class="hlt">glaciers</span> the proper tool to find the correct name for <span class="hlt">glaciers</span> and ice caps in Greenland and to locate <span class="hlt">glaciers</span> described in the historic literature with the old Greenlandic orthography. The data set contains information on the names of 733 <span class="hlt">glaciers</span>, 285 originating from the Greenland Ice Sheet (GrIS) and 448 from local <span class="hlt">glaciers</span> and ice caps (LGICs).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/sir/2012/5210/pdf/sir20125210.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/sir/2012/5210/pdf/sir20125210.pdf"><span>Streamflow record extension for selected streams in the Susitna River <span class="hlt">Basin</span>, Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Curran, Janet H.</p> <p>2012-01-01</p> <p>Daily streamflow records for water years 1950–2010 in the Susitna River <span class="hlt">Basin</span> range in length from 4 to 57 years, and many are distributed within that period in a way that might not adequately represent long-term streamflow conditions. Streamflow in the <span class="hlt">basin</span> is affected by the Pacific Decadal Oscillation (PDO), a multi-decadal climate pattern that shifted from a cool phase to a warm phase in 1976. Records for many streamgages in the <span class="hlt">basin</span> fell mostly within one phase of the PDO, such that monthly and annual statistics from observed records might not reflect streamflow conditions over a longer period. Correlations between daily discharge values sufficed for extending streamflow records at 11 of the 14 streamgages in the <span class="hlt">basin</span> on the basis of relatively long-term records for one or more of the streamgages within the <span class="hlt">basin</span>, or one outside the <span class="hlt">basin</span>, that were defined as index stations. Streamflow at the index stations was hydrologically responsive to <span class="hlt">glacier</span> melt and snowmelt, and correlated well with flow from similar high-elevation, glaciated <span class="hlt">basins</span>, but flow in low-elevation <span class="hlt">basins</span> without <span class="hlt">glaciers</span> could not be correlated to flow at any of the index stations. Kendall-Theil Robust Line multi-segment regression equations developed for one or more index stations were used to extend daily discharge values to the full 61-year period for all 11 streamgages. Monthly and annual statistics prepared for the extended records show shifts in timing of breakup and freeze-up and magnitude of snowmelt peaks largely predicted by the PDO phase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMNH51A1228F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMNH51A1228F"><span>Fuzzy Cognitive Maps for <span class="hlt">Glacier</span> Hazards Assessment: Application to Predicting the Potential for <span class="hlt">Glacier</span> Lake Outbursts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Furfaro, R.; Kargel, J. S.; Fink, W.; Bishop, M. P.</p> <p>2010-12-01</p> <p><span class="hlt">Glaciers</span> and ice sheets are among the largest unstable parts of the solid Earth. Generally, <span class="hlt">glaciers</span> are devoid of resources (other than water), are dangerous, are unstable and no infrastructure is normally built directly on their surfaces. Areas down valley from large alpine <span class="hlt">glaciers</span> are also commonly unstable due to landslide potential of moraines, debris flows, snow avalanches, outburst floods from <span class="hlt">glacier</span> lakes, and other dynamical alpine processes; yet there exists much development and human occupation of some disaster-prone areas. Satellite remote sensing can be extremely effective in providing cost-effective and time- critical information. Space-based imagery can be used to monitor <span class="hlt">glacier</span> outlines and their lakes, including processes such as iceberg calving and debris accumulation, as well as changing thicknesses and flow speeds. Such images can also be used to make preliminary identifications of specific hazardous spots and allows preliminary assessment of possible modes of future disaster occurrence. Autonomous assessment of <span class="hlt">glacier</span> conditions and their potential for hazards would present a major advance and permit systematized analysis of more data than humans can assess. This technical leap will require the design and implementation of Artificial Intelligence (AI) algorithms specifically designed to mimic <span class="hlt">glacier</span> experts’ reasoning. Here, we introduce the theory of Fuzzy Cognitive Maps (FCM) as an AI tool for predicting and assessing natural hazards in alpine <span class="hlt">glacier</span> environments. FCM techniques are employed to represent expert knowledge of <span class="hlt">glaciers</span> physical processes. A cognitive model embedded in a fuzzy logic framework is constructed via the synergistic interaction between glaciologists and AI experts. To verify the effectiveness of the proposed AI methodology as applied to predicting hazards in <span class="hlt">glacier</span> environments, we designed and implemented a FCM that addresses the challenging problem of autonomously assessing the <span class="hlt">Glacier</span> Lake Outburst Flow</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ISPAr42.3.1285M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ISPAr42.3.1285M"><span>Measuring Surface Deformation in <span class="hlt">Glacier</span> Retreated Areas Based on Ps-Insar - Geladandong <span class="hlt">Glacier</span> as a Case Study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mohamadi, B.; Balz, T.</p> <p>2018-04-01</p> <p><span class="hlt">Glaciers</span> are retreating in many parts of the world as a result of global warming. Many researchers consider Qinghai-Tibetan Plateau as a reference for climate change by measuring <span class="hlt">glaciers</span> retreat on the plateau. This retreat resulted in some topographic changes in retreated areas, and in some cases can lead to geohazards as landslides, and rock avalanches, which is known in <span class="hlt">glacier</span> retreated areas as paraglacial slope failure (PSF). In this study, Geladandong biggest and main <span class="hlt">glacier</span> mass was selected to estimate surface deformation on its <span class="hlt">glacier</span> retreated areas and define potential future PSF based on PS-InSAR technique. 56 ascending and 49 descending images were used to fulfill this aim. Geladandong <span class="hlt">glacier</span> retreated areas were defined based on the maximum extent of the <span class="hlt">glacier</span> in the little ice age. Results revealed a general uplift in the <span class="hlt">glacier</span> retreated areas with velocity less than 5mm/year. Obvious surface motion was revealed in seven parts surround <span class="hlt">glacier</span> retreated areas with high relative velocity reached ±60mm/year in some parts. Four parts were considered as PSF potential motion, and two of them showed potential damage for the main road in the study area in case of rock avalanche into recent <span class="hlt">glacier</span> lakes that could result in <span class="hlt">glacier</span> lake outburst flooding heading directly to the road. Finally, further analysis and field investigations are needed to define the main reasons for different types of deformation and estimate future risks of these types of surface motion in the Qinghai-Tibetan Plateau.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70020502','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70020502"><span>Isotopic composition of ice cores and meltwater from upper fremont <span class="hlt">glacier</span> and Galena Creek rock <span class="hlt">glacier</span>, Wyoming</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>DeWayne, Cecil L.; Green, J.R.; Vogt, S.; Michel, R.; Cottrell, G.</p> <p>1998-01-01</p> <p>Meltwater runoff from <span class="hlt">glaciers</span> can result from various sources, including recent precipitation and melted glacial ice. Determining the origin of the meltwater from <span class="hlt">glaciers</span> through isotopic analysis can provide information about such things as the character and distribution of ablation on <span class="hlt">glaciers</span>. A 9.4 m ice core and meltwater were collected in 1995 and 1996 at the glacigenic Galena Creek rock <span class="hlt">glacier</span> in Wyoming's Absaroka Mountains. Measurements of chlorine-36 (36Cl), tritium (3H), sulphur-35 (35S), and delta oxygen-18 (??18O) were compared to similar measurements from an ice core taken from the Upper Fremont <span class="hlt">Glacier</span> in the Wind River Range of Wyoming collected in 1991-95. Meltwater samples from three sites on the rock <span class="hlt">glacier</span> yielded 36Cl concentrations that ranged from 2.1 ?? 1.0 X 106 to 5.8??0.3 X 106 atoms/l. The ice-core 36Cl concentrations from Galena Creek ranged from 3.4??0.3 X 105 to 1.0??0.1 X 106 atoms/l. Analysis of an ice core from the Upper Fremont <span class="hlt">Glacier</span> yielded 36Cl concentrations of 1.2??0.2 X 106 and 5.2??0.2 X 106 atoms/l for pre- 1940 ice and between 2 X 106 and 3 X 106 atoms/l for post-1980 ice. Purdue's PRIME Lab analyzed the ice from the Upper Fremont <span class="hlt">Glacier</span>. The highest concentration of 36Cl in the ice was 77 ?? 2 X 106 atoms/l and was deposited during the peak of atmospheric nuclear weapons testing in the late 1950s. This is an order of magnitude greater than the largest measured concentration from both the Upper Fremont <span class="hlt">Glacier</span> ice core that was not affected by weapons testing fallout and the ice core collected from the Galena Creek rock <span class="hlt">glacier</span>. Tritium concentrations from the rock <span class="hlt">glacier</span> ranged from 9.2??0.6 to 13.2??0.8 tritium units (TU) in the meltwater to -1.3??1.3 TU in the ice core. Concentrations of 3H in the Upper Fremont <span class="hlt">Glacier</span> ice core ranged from 0 TU in the ice older than 50 years to 6-12 TU in the ice deposited in the last 10 years. The maximum 3H concentration in ice from the Upper Fremont <span class="hlt">Glacier</span> deposited in the</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.C41C0685M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.C41C0685M"><span>A Worldwide <span class="hlt">Glacier</span> Information System to go</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mölg, N.; Steinmann, M.; Zemp, M.</p> <p>2016-12-01</p> <p>In the forefront of the Paris Climate Conference COP21 in December 2015, the WGMS and UNESCO jointly launched a <span class="hlt">glacier</span> application for mobile devices. This new information system aims at bringing scientifically sound facts and figures on worldwide <span class="hlt">glacier</span> changes to decision makers at governmental and intergovernmental levels as well as reaching out to the interested public. The wgms <span class="hlt">Glacier</span> App provides a map interface based on satellite images that display all the observed <span class="hlt">glaciers</span> in the user's proximity. Basic information is provided for each <span class="hlt">glacier</span>, including photographs and general information on size and elevation. Graphs with observation data illustrate the <span class="hlt">glacier</span>'s development, along with information on latest principal investigators and their sponsoring agencies as well as detailed explanations of the measurement types. A text search allows the user to filter the <span class="hlt">glacier</span> by name, country, region, measurement type and the current "health" status, i.e. if the <span class="hlt">glacier</span> has gained or lost ice over the past decade. A compass shows the closest observed <span class="hlt">glaciers</span> in all directions from the user's current position. Finally, the card game allows the user to compete against the computer on the best monitored <span class="hlt">glaciers</span> in the world. Our poster provides a visual entrance point to the wgms <span class="hlt">Glacier</span> App and, hence, provides access to fluctuation series of more than 3'700 <span class="hlt">glaciers</span> around the world.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.8348W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.8348W"><span>Reduced melt on debris-covered <span class="hlt">glaciers</span>: investigations from Changri Nup <span class="hlt">Glacier</span>, Nepal</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wagnon, Patrick; Vincent, Christian; Shea, Joseph M.; Immerzeel, Walter W.; Kraaijenbrink, Philip; Shrestha, Dibas; Soruco, Alvaro; Arnaud, Yves; Brun, Fanny; Berthier, Etienne; Futi Sherpa, Sonam</p> <p>2017-04-01</p> <p>Approximately 25% of the <span class="hlt">glacierized</span> area in the Everest region is covered by debris, yet the surface mass balance of debris-covered portions of these <span class="hlt">glaciers</span> has not been measured directly. In this study, ground-based measurements of surface elevation and ice depth are combined with terrestrial photogrammetry, unmanned aerial vehicle (UAV) and satellite elevation models to derive the surface mass balance of the debris-covered tongue of Changri Nup <span class="hlt">Glacier</span>, located in the Everest region. Over the debris-covered tongue, the mean elevation change between 2011 and 2015 is -0.93 m year-1 or -0.84 m water equivalent per year (w.e. a-1). The mean emergence velocity over this region, estimated from the total ice flux through a cross section immediately above the debris-covered zone, is +0.37mw.e. a-1. The debris-covered portion of the <span class="hlt">glacier</span> thus has an area averaged mass balance of -1.21+/-0.2mw.e. a-1 between 5240 and 5525 m above sea level (m a.s.l.). Surface mass balances observed on nearby debris-free <span class="hlt">glaciers</span> suggest that the ablation is strongly reduced (by ca. 1.8mw.e. a-1) by the debris cover. The insulating effect of the debris cover has a larger effect on total mass loss than the enhanced ice ablation due to supraglacial ponds and exposed ice cliffs. This finding contradicts earlier geodetic studies and should be considered for modelling the future evolution of debris-covered <span class="hlt">glaciers</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT.......251T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT.......251T"><span>Flow instabilities of Alaskan <span class="hlt">glaciers</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Turrin, James Bradley</p> <p></p> <p>Over 300 of the largest <span class="hlt">glaciers</span> in southern Alaska have been identified as either surge-type or pulse-type, making <span class="hlt">glaciers</span> with flow instabilities the norm among large <span class="hlt">glaciers</span> in that region. Consequently, the bulk of mass loss due to climate change will come from these unstable <span class="hlt">glaciers</span> in the future, yet their response to future climate warming is unknown because their dynamics are still poorly understood. To help broaden our understanding of unstable <span class="hlt">glacier</span> flow, the decadal-scale ice dynamics of 1 surging and 9 pulsing <span class="hlt">glaciers</span> are investigated. Bering <span class="hlt">Glacier</span> had a kinematic wave moving down its ablation zone at 4.4 +/- 2.0 km/yr from 2002 to 2009, which then accelerated to 13.9 +/- 2.0 km/yr as it traversed the piedmont lobe. The wave first appeared in 2001 near the confluence with Bagley Ice Valley and it took 10 years to travel ~64 km. A surge was triggered in 2008 after the wave activated an ice reservoir in the midablation zone, and it climaxed in 2011 while the terminus advanced several km into Vitus Lake. Ruth <span class="hlt">Glacier</span> pulsed five times between 1973 and 2012, with peak velocities in 1981, 1989, 1997, 2003, and 2010; approximately every 7 years. A typical pulse increased ice velocity 300%, from roughly 40 m/yr to 160 m/yr in the midablation zone, and involved acceleration and deceleration of the ice en masse; no kinematic wave was evident. The pulses are theorized to be due to deformation of a subglacial till causing enhanced basal motion. Eight additional pulsing <span class="hlt">glaciers</span> are identified based on the spatiotemporal pattern of their velocity fields. These <span class="hlt">glaciers</span> pulsed where they were either constricted laterally or joined by a tributary, and their surface slopes are 1-2°. These traits are consistent with an overdeepening. This observation leads to a theory of ice motion in overdeepenings that explains the cyclical behavior of pulsing <span class="hlt">glaciers</span>. It is based on the concept of glaciohydraulic supercooling, and includes sediment transport and erosion</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.C33A..07S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.C33A..07S"><span>Interpretation of ICESat-Derived Elevation Change on the Malaspina-Seward <span class="hlt">Glacier</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sauber, J.; Ramage, J.; Kopczynski, S.; Muskett, R.</p> <p>2005-12-01</p> <p>In this study, we report and interpret ICESat-derived short-term variability in surface elevation in the snow accumulation region of the Seward-Malaspina <span class="hlt">Glacier</span>, one of the largest <span class="hlt">glacier</span> systems in southern Alaska. The Seward-Malaspina complex consists of an extensive icefield, the upper Seward <span class="hlt">Glacier</span>, and a narrower lower outlet <span class="hlt">glacier</span> (lower Seward) through which ice drains to the enormous piedmont of the Malaspina <span class="hlt">Glacier</span>. Although the upper Seward is just 80 km north of the Gulf of Alaska it has an environment more continental than maritime because of shielding afforded by high mountains to the south [Sharp, 1951]. The Malaspina <span class="hlt">Glacier</span> by contrast lies completely within the moist maritime environment of the southern Alaska coast. In an earlier study of the Malaspina <span class="hlt">Glacier</span>, we reported elevation differences between ICESat Laser 1-3 observations (February 2003 - November 2004) and a Shuttle Radar Topography Mission (SRTM)-derived DEM from February 2000 [Sauber et al., 2005]. Elevation decreases of up to 20-25 m over a 3-4 year time period were observed across the folded loop moraine on the southern portion of the piedmont lobe of the Malaspina <span class="hlt">Glacier</span>. For the western portion of the Upper Seward we will estimate elevation change over a comparable time period by using an X-band InSAR-derived DEM from Intermap Tech. (Sept. 2000) and ICESat-derived elevations. Early field measurements (1945-1949) from the Upper Seward <span class="hlt">Glacier</span> indicated an average annual net surplus of 75 cm water equivalent in the Upper Seward <span class="hlt">basin</span> [Sharp, 1951]. However, even over this short time period, Sharp [1951] found large interannual variability in net accumulation of 41-168 cm. To further constrain and understand surface changes, we examined ICESat-derived elevations from a variable set of repeated ICESat upper Seward profiles made between Feb. 2003 and May 2005. Additionally we compared the elevation change profiles to snowmelt timing and ablation season length derived from the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.192..149H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.192..149H"><span>Origin, transport and deposition of leaf-wax biomarkers in the Amazon <span class="hlt">Basin</span> and the <span class="hlt">adjacent</span> Atlantic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Häggi, Christoph; Sawakuchi, André O.; Chiessi, Cristiano M.; Mulitza, Stefan; Mollenhauer, Gesine; Sawakuchi, Henrique O.; Baker, Paul A.; Zabel, Matthias; Schefuß, Enno</p> <p>2016-11-01</p> <p>-chain n-alkanes from the Amazon estuary and plume represent an integrated signal of different regions of the onshore <span class="hlt">basin</span>. Our results also imply that n-alkanes are not extensively remineralized during transport and that the signal at the Amazon estuary and plume includes refractory compounds derived from the western sector of the <span class="hlt">Basin</span>. These findings will aid in the interpretation of plant wax-based records of marine sediment cores collected from the <span class="hlt">adjacent</span> ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70155990','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70155990"><span>Surface melt dominates Alaska <span class="hlt">glacier</span> mass balance</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Larsen Chris F,; Burgess, E; Arendt, A.A.; O'Neel, Shad; Johnson, A.J.; Kienholz, C.</p> <p>2015-01-01</p> <p>Mountain <span class="hlt">glaciers</span> comprise a small and widely distributed fraction of the world's terrestrial ice, yet their rapid losses presently drive a large percentage of the cryosphere's contribution to sea level rise. Regional mass balance assessments are challenging over large <span class="hlt">glacier</span> populations due to remote and rugged geography, variable response of individual <span class="hlt">glaciers</span> to climate change, and episodic calving losses from tidewater <span class="hlt">glaciers</span>. In Alaska, we use airborne altimetry from 116 <span class="hlt">glaciers</span> to estimate a regional mass balance of −75 ± 11 Gt yr−1 (1994–2013). Our <span class="hlt">glacier</span> sample is spatially well distributed, yet pervasive variability in mass balances obscures geospatial and climatic relationships. However, for the first time, these data allow the partitioning of regional mass balance by <span class="hlt">glacier</span> type. We find that tidewater <span class="hlt">glaciers</span> are losing mass at substantially slower rates than other <span class="hlt">glaciers</span> in Alaska and collectively contribute to only 6% of the regional mass loss.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=dependency&id=EJ1118831','ERIC'); return false;" href="https://eric.ed.gov/?q=dependency&id=EJ1118831"><span>Gleaning Structure from Sound: The Role of Prosodic Contrast in Learning <span class="hlt">Non-Adjacent</span> Dependencies</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Grama, Ileana C.; Kerkhoff, Annemarie; Wijnen, Frank</p> <p>2016-01-01</p> <p>The ability to detect <span class="hlt">non-adjacent</span> dependencies (i.e. between "a" and "b" in "aXb") in spoken input may support the acquisition of morpho-syntactic dependencies (e.g. "The princess 'is' kiss'ing' the frog"). Functional morphemes in morpho-syntactic dependencies are often marked by perceptual cues that render…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.3107H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.3107H"><span>Evaluation of a distributed energy balance model for a high-altitude <span class="hlt">glacier</span> on the Tibetan Plateau using a time lapse camera system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huintjes, Eva; Sauter, Tobias; Krenscher, Tobias; Maussion, Fabien; Kropacek, Jan; Yang, Wei; Zhang, Guoshuai; Kang, Shichang; Buchroithner, Manfred; Scherer, Dieter; Schneider, Christoph</p> <p>2013-04-01</p> <p>In the remote and high-altitude mountain areas of the Tibetan Plateau, climate observations as well as <span class="hlt">glacier</span>-wide mass and energy balance determinations are scarce. Therefore, the application of models to determine reliable information on mass balance and runoff is important. Simultaneously, these circumstances make it difficult to evaluate the models. Since 2009, we operate an automatic weather station (AWS) in the ablation zone of Zhadang <span class="hlt">Glacier</span> (5.665 m a.s.l.). The <span class="hlt">glacier</span> is easily accessible. It is situated in the southern-central part of the Tibetan Plateau (30.5°N) in the Nam Co drainage <span class="hlt">basin</span> and ranges between 5.400 and 5.900 m a.s.l. Based on these measurements over 2009-2012, we run and evaluate a physically based, distributed energy and mass balance model. The applied model couples an energy balance to a multilayer snow model and therefore accounts for subsurface processes like refreezing, subsurface melt and densification of the snowpack. First, the model is evaluated at point scale against measurements from the AWS. The results show that modelled accumulation and ablation patterns reproduce the observed changes in surface height very well. To evaluate the distributed model, we use daily images of a time lapse camera system installed nearby the <span class="hlt">glacier</span> over 2010-2012. Therefore the <span class="hlt">non</span> calibrated slope images had to be orthorectified using ground control points measured during field campaigns. The temporally and spatially highly resolved time series allows a detailed evaluation of the distributed energy balance model by analyzing the spatial and temporal heterogeneity of the snow line during the ablation season. First results show that the model captures the observed spatial heterogeneity of melt on the <span class="hlt">glacier</span> surface. Subsequently to the evaluation the model will be applied on several <span class="hlt">glaciers</span> and small ice caps in remote areas on the Tibetan Plateau to determine the linkages between climate fluctuations and <span class="hlt">glacier</span> variability. The work is part</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C41B1217V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C41B1217V"><span>Comparison of Glaciological and Gravimetric <span class="hlt">Glacier</span> Mass Balance Measurements of Taku and Lemon Creek <span class="hlt">Glaciers</span>, Southeast Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vogler, K.; McNeil, C.; Bond, M.; Getraer, B.; Huxley-Reicher, B.; McNamara, G.; Reinhardt-Ertman, T.; Silverwood, J.; Kienholz, C.; Beedle, M. J.</p> <p>2017-12-01</p> <p><span class="hlt">Glacier</span>-wide annual mass balances (Ba) have been calculated for Taku (726 km2) and Lemon Creek <span class="hlt">glaciers</span> (10.2 km2) since 1946 and 1953 respectively. These are the longest mass balance records in North America, and the only Ba time-series available for Southeast Alaska, making them particularly valuable for the global <span class="hlt">glacier</span> mass balance monitoring network. We compared Ba time-series from Taku and Lemon Creek <span class="hlt">glaciers</span> to Gravity Recovery and Climate Experiment (GRACE) mascon solutions (1352 and 1353) during the 2004-2015 period to assess how well these gravimetric solutions reflect individual glaciological records. Lemon Creek <span class="hlt">Glacier</span> is a challenging candidate for this comparison because it is small compared to the 12,100 km2 GRACE mascon solutions. Taku <span class="hlt">Glacier</span> is equally challenging because its mass balance is stable compared to the negative balances dominating its neighboring <span class="hlt">glaciers</span>. Challenges notwithstanding, a high correlation between the glaciological and gravimetrically-derived Ba for Taku and Lemon Creek <span class="hlt">glaciers</span> encourage future use of GRACE to measure <span class="hlt">glacier</span> mass balance. Additionally, we employed high frequency ground penetrating radar (GPR) to measure the variability of accumulation around glaciological sites to assess uncertainty in our glaciological measurements, and the resulting impact to Ba. Finally, we synthesize this comparison of glaciological and gravimetric mass balance solutions with a discussion of potential sources of error in both methods and their combined utility for measuring regional <span class="hlt">glacier</span> change during the 21st century.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70031882','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70031882"><span>Distribution and spawning dynamics of capelin (Mallotus villosus) in <span class="hlt">Glacier</span> Bay, Alaska: A cold water refugium</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Arimitsu, Mayumi L.; Piatt, John F.; Litzow, Michael A.; Abookire, Alisa A.; Romano, Marc D.; Robards, Martin D.</p> <p>2008-01-01</p> <p>Pacific capelin (Mallotus villosus) populations declined dramatically in the Northeastern Pacific following ocean warming after the regime shift of 1977, but little is known about the cause of the decline or the functional relationships between capelin and their environment. We assessed the distribution and abundance of spawning, <span class="hlt">non</span>-spawning adult and larval capelin in <span class="hlt">Glacier</span> Bay, an estuarine fjord system in southeastern Alaska. We used principal components analysis to analyze midwater trawl and beach seine data collected between 1999 and 2004 with respect to oceanographic data and other measures of physical habitat including proximity to tidewater <span class="hlt">glaciers</span> and potential spawning habitat. Both spawning and <span class="hlt">non</span>-spawning adult Pacific capelin were more likely to occur in areas closest to tidewater <span class="hlt">glaciers</span>, and those areas were distinguished by lower temperature, higher turbidity, higher dissolved oxygen and lower chlorophyll a levels when compared with other areas of the bay. The distribution of larval Pacific capelin was not sensitive to glacial influence. Pre-spawning females collected farther from tidewater <span class="hlt">glaciers</span> were at a lower maturity state than those sampled closer to tidewater <span class="hlt">glaciers</span>, and the geographic variation in the onset of spawning is likely the result of differences in the marine habitat among sub-areas of <span class="hlt">Glacier</span> Bay. Proximity to cold water in <span class="hlt">Glacier</span> Bay may have provided a refuge for capelin during the recent warm years in the Gulf of Alaska.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C31B0285T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C31B0285T"><span>Monitoring of High Mountain <span class="hlt">Glaciers</span> in the Vicinity of Everest (Himalaya) using Remote Sensing Capability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thakuri, S.; Salerno, F.; Bolch, T.; Smiraglia, C.; Tartari, G.</p> <p>2014-12-01</p> <p>Himalayan <span class="hlt">glaciers</span> are of crucial interest due to their role in the cryospheric system and hydrology. This contribution examines <span class="hlt">glacier</span> changes between 1960s and 2013 using satellite data. The study is focused in 3 <span class="hlt">basins</span> in Nepal: Upper Sun Koshi (USKB; 2850 km2), Dudh Koshi (DKB; 3720 km2), and Tamor (TB; 5875 km2). We observed an overall <span class="hlt">glacier</span> surface loss of 0.19 ± 0.26 % a-1 (146.1 to 136.9 km2) in SKB for 1975-2013 period; 0.27 ± 0.06 % a-1 (404.6 to 351.8 km2) in the DKB for 1962-2011, and 8.4% (0.25 ± 0.29 % a-1; 610.9 to 559.3 km2) in the TB for 1975-2009 period. In the DKB, we observed an upward shift of snow-line altitude (ΔSLA) by more than 180 m, a terminus retreat of on average ~ 400 m, and an increase of 17.6 ± 3.1% in debris coverage between 1962 and 2011. Moreover, we observed that (i) <span class="hlt">glaciers</span> with increased debris cover have experienced a reduced termini retreat; (ii) negative mass balances (i.e., ΔSLA) induce increases of debris coverage; (iii) slight, but statistically insignificant acceleration of the surface area loss since early 1990s; but a significant loss for the largest <span class="hlt">glaciers</span> (>10 km2) that have accumulation zones at higher elevations and along the preferable south-north direction of the monsoon; (iv) a significant ΔSLA; moreover, the largest <span class="hlt">glaciers</span> present median ΔSLA that are nearly double than that of the smallest; this finding leads to a hypothesis that these <span class="hlt">glaciers</span> are shrinking, not only due to warming temperatures, but also as a result of decreasing precipitation due to a weakening Asian monsoons registered over the last few decades. Furthermore, we present first results on the geodetic <span class="hlt">glacier</span> mass and velocity changes of selected <span class="hlt">glaciers</span>, and climatic trends. In fact, less accumulation due to the observed decrease of precipitation should cause lower <span class="hlt">glacier</span> flow velocity until to the ice stagnation of tongues as observed by other previous studies in the region. Finally, we compared our findings with other</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001486.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001486.html"><span><span class="hlt">Glaciers</span> and Sea Level Rise</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-08</p> <p>Calving front of the Upsala <span class="hlt">Glacier</span> (Argentina). This <span class="hlt">glacier</span> has been thinning and retreating at a rapid rate during the last decades – from 2006 to 2010, it receded 43.7 yards (40 meters) per year. During summer 2012, large calving events prevented boat access to the <span class="hlt">glacier</span>. To learn about the contributions of <span class="hlt">glaciers</span> to sea level rise, visit: www.nasa.gov/topics/earth/features/<span class="hlt">glacier</span>-sea-rise.html Credit: Etienne Berthier, Université de Toulouse NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA20745.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA20745.html"><span>Glorious <span class="hlt">Glacier</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2016-07-15</p> <p>This image has low-sun lighting that accentuates the many transverse ridges on this slope, extending from Euripus Mons (mountains). These flow-like structures were previously called "lobate debris aprons," but the Shallow Radar (SHARAD) instrument on MRO has shown that they are actually debris-covered flows of ice, or <span class="hlt">glaciers</span>. There is no evidence for present-day flow of these <span class="hlt">glaciers</span>, so they appear to be remnants of past climates. http://photojournal.jpl.nasa.gov/catalog/PIA20745</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Tectp.726...62C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Tectp.726...62C"><span>Lithospheric structure of the South China Sea and <span class="hlt">adjacent</span> regions: Results from potential field modelling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Ming; Fang, Jian; Cui, Ronghua</p> <p>2018-02-01</p> <p>This work aims to investigate the crustal and lithospheric mantle thickness of the South China Sea (SCS) and <span class="hlt">adjacent</span> regions. The crust-mantle interface, average crustal density, and lithospheric mantle base are calculated from free-air gravity anomaly and topographic data using an iterative inversion method. We construct a three-dimensional lithospheric model with different hierarchical layers. The satellite-derived gravity is used to invert the average crustal density and Moho (crust-mantle interface) undulations. The average crustal density and LAB (lithosphere-asthenosphere boundary) depths are further adjusted by topographic data under the assumption of local isostasy. The average difference in Moho depths between this study and the seismic measurement results is <1.5 km. The results show that in oceanic regions, the Moho depths are 7.5-30 km and the LAB depths are 65-120 km. The lithospheric thickness of the SCS <span class="hlt">basin</span> and the <span class="hlt">adjacent</span> regions increases from the sea <span class="hlt">basin</span> to the continental margin with a large gradient in the ocean-continent transition zones. The Moho depths of conjugate plots during the opening of SCS, Zhongsha Islands and Reed Bank, reveal the asymmetric spreading pattern of SCS seafloor spreading. The lithospheric thinning pattern indicate two different spreading directions during seafloor spreading, which changed from N-S to NW-SE after the southward transition of the spreading axis. The lithosphere of the SCS <span class="hlt">basin</span> and <span class="hlt">adjacent</span> regions indicate that the SCS <span class="hlt">basin</span> is a young <span class="hlt">basin</span> with a stable interior lithosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C41B1199R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C41B1199R"><span>Recent Developments of the GLIMS <span class="hlt">Glacier</span> Database</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raup, B. H.; Berthier, E.; Bolch, T.; Kargel, J. S.; Paul, F.; Racoviteanu, A.</p> <p>2017-12-01</p> <p>Earth's <span class="hlt">glaciers</span> are shrinking almost without exception, leading to changes in water resources, timing of runoff, sea level, and hazard potential. Repeat mapping of <span class="hlt">glacier</span> outlines, lakes, and <span class="hlt">glacier</span> topography, along with glacial processes, is critically needed to understand how <span class="hlt">glaciers</span> will react to a changing climate, and how those changes will impact humans. To understand the impacts and processes behind the observed changes, it is crucial to monitor <span class="hlt">glaciers</span> through time by mapping their areal extent, snow lines, ice flow velocities, associated water bodies, and thickness changes. The <span class="hlt">glacier</span> database of the Global Land Ice Measurements from Space (GLIMS) initiative is the only multi-temporal <span class="hlt">glacier</span> database capable of tracking all these <span class="hlt">glacier</span> measurements and providing them to the scientific community and broader public.Recent developments in GLIMS include improvements in the database and web applications and new activities in the international GLIMS community. The coverage of the GLIMS database has recently grown geographically and temporally by drawing on the Randolph <span class="hlt">Glacier</span> Inventory (RGI) and other new data sets. The GLIMS database is globally complete, and approximately one third of <span class="hlt">glaciers</span> have outlines from more than one time. New tools for visualizing and downloading GLIMS data in a choice of formats and data models have been developed, and a new data model for handling multiple <span class="hlt">glacier</span> records through time while avoiding double-counting of <span class="hlt">glacier</span> number or area is nearing completion. A GLIMS workshop was held in Boulder, Colorado this year to facilitate two-way communication with the greater community on future needs.The result of this work is a more complete and accurate <span class="hlt">glacier</span> data repository that shows both the current state of <span class="hlt">glaciers</span> on Earth and how they have changed in recent decades. Needs for future scientific and technical developments were identified and prioritized at the GLIMS Workshop, and are reported here.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/59504','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/59504"><span>Aeromagnetic map of the <span class="hlt">Glacier</span> Peak Wilderness and <span class="hlt">adjacent</span> areas, Chelan, Skagit, and Snohomish counties, Washington</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Flanigan, V.J.; Sherrard, Mark</p> <p>1985-01-01</p> <p>The <span class="hlt">Glacier</span> Peak Wilderness encompasses 464,741 acres, including 483 acres of patented mining and millsite claims. Also included in the present study are nine areas adjoining the wilderness (see fig. 1), totaling 90,034 acres of recommended wilderness additions. All these lands are here collectively called the “study area.” Access to the study area is provided by generally well maintained trails from gravel or dirt roads along major valleys above Darrington, Marblemount, Stehekin, Holden, Trinity, and Lake Wnatchee. Other than the main access trails across a few passes (Cloudy Pass, Buck Creek Pass, White Pass, and Indian Pass), trails are rough, infrequently maintained, or nonexistent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017QSRv..156..121K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017QSRv..156..121K"><span>Latest Pleistocene advance and collapse of the Matanuska - Knik <span class="hlt">glacier</span> system, Anchorage Lowland, southern Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kopczynski, Sarah E.; Kelley, Samuel E.; Lowell, Thomas V.; Evenson, Edward B.; Applegate, Patrick J.</p> <p>2017-01-01</p> <p>At the end of the last ice age, <span class="hlt">glacier</span> systems worldwide underwent dramatic retreat. Here, we document the advance and retreat of a <span class="hlt">glacier</span> system with <span class="hlt">adjacent</span> marine- and land-based components during the latter part of the Termination. We utilize three lines of evidence: lithologic provenance, geomorphic mapping, and radiocarbon ages derived from lake cores to reconstruct <span class="hlt">glacier</span> extent and timing of advance and retreat within our study area centered at N 61.50°, W 149.50°, just north of Anchorage, Alaska. Two <span class="hlt">glaciers</span>, sourced in the Talkeetna and Chugach Mountains, flowed down the Matanuska and Knik Valleys forming a coalesced lobe that advanced onto the Anchorage Lowlands and terminated at Elmendorf Moraine. We use the presence of lithologies unique to the Matanuska catchment in glacial drift to delineate the paleoflow lines and to estimate the suture line of the two <span class="hlt">glacier</span> systems. The eastern side of the lobe, attributed to ice flow from the Knik Valley, was in contact with elevated marine waters within the Knik Arm fjord, and thus retreat was likely dominated by calving. Geomorphic evidence suggests the western side of the lobe, attributed to ice flow from Matanuska Valley, retreated due to stagnation. We constrain retreat of the combined Matanuska and Knik lobe with thirteen new radiocarbon ages, in addition to previously published radiocarbon ages, and with geomorphic evidence suggesting the retreat occurred in two phases. Retreat from the Elmendorf Moraine began between 16.8 and 16.4 ka BP. A second, faster retreat phase occurred later and was completed by 13.7 ka BP. With the 140 km of total retreat occurring over ∼3000 years or less. This pattern of glacial advance and retreats agrees well with the deglacial histories from the southern sectors of the Cordilleran Ice Sheet, as well as many other alpine <span class="hlt">glacier</span> systems in the western U.S. and northern Alaska. This consistent behavior of <span class="hlt">glacier</span> systems may indicate that climate oscillated over</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70019284','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70019284"><span><span class="hlt">Glacier</span> generated floods</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Walder, J.S.; Fountain, A.G.; ,</p> <p>1997-01-01</p> <p>Destructive floods result from drainage of <span class="hlt">glacier</span>-dammed lakes and sudden release of water stored within <span class="hlt">glaciers</span>. There is a good basis - both empirical and theoretical - for predicting the magnitude of floods from ice-dammed lakes, although some aspects of flood initiation need to be better understood. In contrast, an understanding of floods resulting from release of internally stored water remains elusive, owing to lack of knowledge of how and where water is stored and to inadequate understanding of the complex physics of the temporally and spatially variable subglacial drainage system.Destructive floods result from drainage of <span class="hlt">glacier</span>-dammed lakes and sudden release of water stored within <span class="hlt">glaciers</span>. There is a good basis - both empirical and theoretical - for predicting the magnitude of floods from ice-dammed lakes, although some aspects of flood initiation need to be better understood. In contrast, an understanding of floods resulting from release of internally stored water remains elusive, owing to lack of knowledge of how and where water is stored and to inadequate understanding of the complex physics of the temporally and spatially variable subglacial drainage system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.4842H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.4842H"><span>Internationally coordinated <span class="hlt">glacier</span> monitoring: strategy and datasets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hoelzle, Martin; Armstrong, Richard; Fetterer, Florence; Gärtner-Roer, Isabelle; Haeberli, Wilfried; Kääb, Andreas; Kargel, Jeff; Nussbaumer, Samuel; Paul, Frank; Raup, Bruce; Zemp, Michael</p> <p>2014-05-01</p> <p>Internationally coordinated monitoring of long-term <span class="hlt">glacier</span> changes provide key indicator data about global climate change and began in the year 1894 as an internationally coordinated effort to establish standardized observations. Today, world-wide monitoring of <span class="hlt">glaciers</span> and ice caps is embedded within the Global Climate Observing System (GCOS) in support of the United Nations Framework Convention on Climate Change (UNFCCC) as an important Essential Climate Variable (ECV). The Global Terrestrial Network for <span class="hlt">Glaciers</span> (GTN-G) was established in 1999 with the task of coordinating measurements and to ensure the continuous development and adaptation of the international strategies to the long-term needs of users in science and policy. The basic monitoring principles must be relevant, feasible, comprehensive and understandable to a wider scientific community as well as to policy makers and the general public. Data access has to be free and unrestricted, the quality of the standardized and calibrated data must be high and a combination of detailed process studies at selected field sites with global coverage by satellite remote sensing is envisaged. Recently a GTN-G Steering Committee was established to guide and advise the operational bodies responsible for the international <span class="hlt">glacier</span> monitoring, which are the World <span class="hlt">Glacier</span> Monitoring Service (WGMS), the US National Snow and Ice Data Center (NSIDC), and the Global Land Ice Measurements from Space (GLIMS) initiative. Several online databases containing a wealth of diverse data types having different levels of detail and global coverage provide fast access to continuously updated information on <span class="hlt">glacier</span> fluctuation and inventory data. For world-wide inventories, data are now available through (a) the World <span class="hlt">Glacier</span> Inventory containing tabular information of about 130,000 <span class="hlt">glaciers</span> covering an area of around 240,000 km2, (b) the GLIMS-database containing digital outlines of around 118,000 <span class="hlt">glaciers</span> with different time stamps and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=170624&keyword=legal&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=170624&keyword=legal&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span><span class="hlt">NON</span>-NAVIGABLE STREAMS AND <span class="hlt">ADJACENT</span> WETLANDS: ADDRESSING SCIENCE NEEDS FOLLOWING THE SUPREME COURT'S RAPANOS DECISION</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>In June of 2006, the US Supreme Court ruled in two cases concerning jurisdiction under the Clean Water Act (CWA). The decisions suggest that hydrological permanence of <span class="hlt">non</span>-navigable streams and <span class="hlt">adjacent</span> wetlands (NNSAWs) and their effects on the chemical, physical, and biological...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C42B..05M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C42B..05M"><span>Quantifying Tropical <span class="hlt">Glacier</span> Mass Balance Sensitivity to Climate Change Through Regional-Scale Modeling and The Randolph <span class="hlt">Glacier</span> Inventory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Malone, A.</p> <p>2017-12-01</p> <p>Quantifying mass balance sensitivity to climate change is essential for forecasting <span class="hlt">glacier</span> evolution and deciphering climate signals embedded in archives of past <span class="hlt">glacier</span> changes. Ideally, these quantifications result from decades of field measurement, remote sensing, and a hierarchy modeling approach, but in data-sparse regions, such as the Himalayas and tropical Andes, regional-scale modeling rooted in first principles provides a first-order picture. Previous regional-scaling modeling studies have applied a surface energy and mass balance approach in order to quantify equilibrium line altitude sensitivity to climate change. In this study, an expanded regional-scale surface energy and mass balance model is implemented to quantify <span class="hlt">glacier</span>-wide mass balance sensitivity to climate change for tropical Andean <span class="hlt">glaciers</span>. Data from the Randolph <span class="hlt">Glacier</span> Inventory are incorporated, and additional physical processes are included, such as a dynamic albedo and cloud-dependent atmospheric emissivity. The model output agrees well with the limited mass balance records for tropical Andean <span class="hlt">glaciers</span>. The dominant climate variables driving interannual mass balance variability differ depending on the climate setting. For wet tropical <span class="hlt">glaciers</span> (annual precipitation >0.75 m y-1), temperature is the dominant climate variable. Different hypotheses for the processes linking wet tropical <span class="hlt">glacier</span> mass balance variability to temperature are evaluated. The results support the hypothesis that <span class="hlt">glacier</span>-wide mass balance on wet tropical <span class="hlt">glaciers</span> is largely dominated by processes at the lowest elevation where temperature plays a leading role in energy exchanges. This research also highlights the transient nature of wet tropical <span class="hlt">glaciers</span> - the vast majority of tropical <span class="hlt">glaciers</span> and a vital regional water resource - in an anthropogenic warming world.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1811722N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1811722N"><span>Inspection of Alpine <span class="hlt">glaciers</span> with cosmic-ray muon radiography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nishiyama, Ryuichi; Ariga, Akitaka; Ariga, Tomoko; Ereditato, Antonio; Lechmann, Alessandro; Mair, David; Scampoli, Paola; Schlunegger, Fritz; Vladymyrov, Mykhailo</p> <p>2016-04-01</p> <p>Radiography using cosmic-ray muons represents a challenging method for probing the bedrock topography beneath Alpine <span class="hlt">glaciers</span>. We present the current status of our feasibility study at Eiger <span class="hlt">glacier</span>, situated on the western flank of the Eiger in the Jungfrau region, Central Swiss Alps. The muon radiography is a technique that has been recently developed to investigate the internal density profiles of geoscientific targets. It is based on the measurement of the absorption of the cosmic-ray muons inside a material. Because the energy spectrum of cosmic-ray muons and the energy dependence of muon range have been studied well during the past years, the attenuation of the muon flux can be used to derive the column density, i.e. the density integrated along the muon trajectories, of geoscientific targets. This technique has recently been applied for <span class="hlt">non</span>-invasive inspection of volcanoes, nuclear reactors, seismic faults, caves and etc. The greatest advantage of the method in the field of <span class="hlt">glacier</span> studies is that it yields a unique solution of the density underneath a <span class="hlt">glacier</span> without any assumption of physical properties inside the target. Large density contrasts, as expected between <span class="hlt">glacier</span> ice (˜ 1.0g/cm3) and bedrock (˜ 2.5g/cm3), would allow us to elucidate the shape of the bedrock in high resolution. Accordingly, this technology will provide for the first time information on the bedrock surface beneath a steep and <span class="hlt">non</span>-accessible Alpine <span class="hlt">glacier</span>, in a complementary way with respect to other exploration methods (drilling, ground penetrating radar, seismic survey, gravity explorations and etc.). Our first aim is to demonstrate the feasibility of the method through a case study at the Eiger <span class="hlt">glacier</span>, situated in the Central Swiss Alps. The Eiger <span class="hlt">glacier</span> straddles the western flank of the Eiger between 3700 and 2300 m above sea level (a.s.l.). The <span class="hlt">glacier</span> has shortened by about 150 m during the past 30 years in response to the ongoing global warming, causing a concern for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/prof/p1386c/','USGSPUBS'); return false;" href="https://pubs.usgs.gov/prof/p1386c/"><span><span class="hlt">Glaciers</span> of Greenland</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Williams, Richard S.; Ferrigno, Jane G.</p> <p>1995-01-01</p> <p>Landsat imagery, combined with aerial photography, sketch maps, and diagrams, is used as the basis for a description of the geography, climatology, and glaciology, including mass balance, variation, and hazards, of the Greenland ice sheet and local ice caps and <span class="hlt">glaciers</span>. The Greenland ice sheet, with an estimated area of 1,736,095+/-100 km2 and volume of 2,600,000 km3, is the second largest <span class="hlt">glacier</span> on the planet and the largest relict of the Ice Age in the Northern Hemisphere. Greenland also has 48,599+/-100 km2 of local ice caps and other types of <span class="hlt">glaciers</span> in coastal areas and islands beyond the margin of the ice sheet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C21F1174L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C21F1174L"><span>Challenging the Southern Boundary of Active Rock <span class="hlt">Glaciers</span> in West Greenland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Langley, K.; Abermann, J.</p> <p>2017-12-01</p> <p>Rock <span class="hlt">glaciers</span> are permafrost features abundant in mountainous environments and are characterized as `steadily creeping perennially frozen and ice-rich debris on <span class="hlt">non</span>-glacierised mountain slopes'. Previous studies investigated both the climatic significance and the dynamics of rock <span class="hlt">glaciers</span> in Greenland, however, there do not exist studies as far south as the Godthåbsfjord area. We recently found evidence of a active rock <span class="hlt">glacier</span> near Nuuk, around 250 km further south than the previously suggested southern active limit. It shows no signs of pioneer vegetation, which supports its likely dynamic activity. The rock <span class="hlt">glacier</span> covers an area of ca. 1 km2and its lowest point is at an elevation of about 250 m a.s.l. Here we present the results of a two year field campaign designed to (I) confirm or reject active rock <span class="hlt">glacier</span> occurrence in the Godthåbsfjord area with innovative methods, (II) study their dynamic regime and (III) investigate the climatic boundary conditions necessary for active rock <span class="hlt">glacier</span> occurrence in the Sub-Arctic. We use a number of methods to determine the state of the rock <span class="hlt">glacier</span>. Movement of the landform is assessed using repeat GPS surveying of marked stones and feature tracking based on ortho-photos and DEMs from repeat UAV deployments. Bottom temperature of snow cover (BTS) measurements give an independent first-order estimate of permafrost occurrence. An air temperature sensor deployed near the snout and recording hourly gives a first order estimate of the temperature gradients between Nuuk and the rock <span class="hlt">glacier</span>, allowing us to assess the climatic boundary conditions required for rock <span class="hlt">glacier</span> occurrence. BTS measurements show a clear drop in temperatures over the rock <span class="hlt">glacier</span> compared to the surrounding areas suggesting an active landform with a well demarcated thermal regime. We will assess this independently with the repeat GPS and UAV surveys and will thus be able to confirm or reject the hypothesis of activity by the end of summer 2017.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70019641','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70019641"><span>Evaluation of conditions along the grounding line of temperate marine <span class="hlt">glaciers</span>: An example from Muir Inlet, <span class="hlt">Glacier</span> Bay, Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Seramur, K.C.; Powell, R.D.; Carlson, P.R.</p> <p>1997-01-01</p> <p> deposited within the Muir Inlet morainal bank complex at an average annual sediment accumulation rate of 2.3 x 107 m3/a. This rate represents the annual sediment production capacity of the <span class="hlt">glacier</span> when the Muir Inlet drainage <span class="hlt">basin</span> is filled with glacial ice.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.T51D2955H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.T51D2955H"><span>Carboniferous Proto-type <span class="hlt">Basin</span> Evolution of Junggar <span class="hlt">Basin</span> in Northwest China: Implications for the Growth Models of Central Asia Orogenic Belt</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>He, D.</p> <p>2016-12-01</p> <p>The Junggar <span class="hlt">Basin</span> locates in the central part of Paleo-Asian Ocean tectonic domain, and records the dynamic processes of the Central Asian Orogenic Belt from subduction-accretion-collision to later intracontinental deformations. Carboniferous is the key period from subduction to closure in the tectonic evolution of Paleo-Asian Ocean. Based on the borehole, outcrop, seismic and gravity and magnetic anomaly data, the paper made analysis of the Carboniferous <span class="hlt">basin</span> evolution.Geo-chronological results for the borehole volcanic rocks suggest that the Junggar <span class="hlt">Basin</span> and <span class="hlt">adjacent</span> area had five periods of volcanic activities, including two periods in the Early Carboniferous (359-347Ma 347-331Ma and 331-324Ma) and three periods in the Late Carboniferous (323-307Ma and 307-300Ma). Regional unconformities divided the Carboniferous into two tectono-stratigraphic sequences: Lower Carboniferous and Upper Carboniferous. The former is characterized by compressional structures and involves massive calc-alkaline basalts, andesites, dacites and rhyolites, whereas the later is mainly controlled by extensional faults and dominated by intermediate-mafic volcanic rocks, with bimodal volcanic rocks in parts. The paper determined four Carboniferous arc-<span class="hlt">basin</span> belts in the Junggar <span class="hlt">Basin</span> and <span class="hlt">adjacent</span> area from north to south: the Saur-Fuhai-Dulate, Heshituoluogai-Wulungu-Yemaquan, Darbut-Luliang-Karamaili, and Zhongguai-Mosuowan-Baijiahai-Qitai, and identified multi-type <span class="hlt">basins</span>, such as fore-arc <span class="hlt">basin</span>, retro-arc <span class="hlt">basin</span>, intra-arc rift <span class="hlt">basin</span>, foreland <span class="hlt">basin</span> and passive continental margin <span class="hlt">basin</span>,etc.. The Carboniferous proto-type <span class="hlt">basin</span> evolution of the Junggar <span class="hlt">Basin</span> can be divided into three phases such as, the early to middle Early Carboniferous subduction-related compressional phase, the late Early Carboniferous to middle Late Carboniferous subduction-related extensional phase and the late Late Carboniferous intra-continental fault-sag phase. The study discloses that the Junggar <span class="hlt">Basin</span> is likely</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C41B0340L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C41B0340L"><span>Heterogeneous Status of Glacial Terminal-Contacted Lakes in Himalayas Due to Different Geomorphology and <span class="hlt">Glacier</span> Characters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Q.; Nie, Y.; Liu, S.</p> <p>2014-12-01</p> <p>Widespread expanding of glacial lakes around the Himalayas, which has led (or will lead) to hazard risks in their downstream valleys due to the potential glacial outburst flood (GLOF), has been widely reported during the past decades. Among all type of glacial lakes, those lakes contacted with the terminals of modern <span class="hlt">glaciers</span> are generally found experienced most remarkable area increases. That is mostly due to the coupled processes, such as calving, between the lake growths and ice tongue retreats. Thermal absorption and convection of lake water are important for calving at the ice cliff or sub-marine melting under the supra-ponded water bodies. Currently, many larger moraine dammed lakes, e. g., Imja Tsho (Nepal) and Longbasaba Lake (China), are observed undergoing remarkable growths and synchronically with the rapid ice margin collapses due to calving. Some newly formed and rapidly growing supraglacial lakes are also identified on the debris-covered region of Himalayan <span class="hlt">glaciers</span>, e. g., the Rongbuk <span class="hlt">Glacier</span> (China), Ngozumpa <span class="hlt">Glacier</span> (Nepal) and Thorthormi <span class="hlt">Glacier</span> (Butan), which are speculated to experience accelerated expanding in the near future and finally developing as bigger terminal-calving lakes. However, not all such lake-<span class="hlt">glacier</span> systems present the same scenes. After experienced the phases of rapid lake growth and terminal retreat, despite the contacting and calving still existing, the positions of the calving lines may be balanced by the positive advances of the ice tongue. We have observed several lakes with stagnation of growth or even shrinkage in lake area as the advance of the calving ice margin. The heterogeneous status of these ice-contacted glacial lakes are mainly due to the different local geomorphology (e. g., slope, lake-<span class="hlt">basin</span> shape and valley aspect) and <span class="hlt">glacier</span> characters (e. g., debris cover, velocity and mass balance). These related factors are important for both the prediction of lake and <span class="hlt">glacier</span> changes and the evaluation of GLOF hazards</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.C31C0454Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.C31C0454Y"><span>The recent <span class="hlt">glacier</span> changes in Mongolian Altai Mountains</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yabuki, H.; Ohata, T.</p> <p>2009-12-01</p> <p>In the 4th IPCC report (AR-4) is reported that global warming in recent years is a clear thing. Shrinkage of the mountain <span class="hlt">glacier</span> and two poles is reporting as an observation fact as the actual condition of the cryosphere by warming. There are mass balance reports of the <span class="hlt">glacier</span> of 80 of world by WGMS (World <span class="hlt">Glacier</span> Monitoring Service) as a report of the actual condition of <span class="hlt">glacier</span> mass balance change, and the actual condition of the <span class="hlt">glacier</span> mass change in world is clarified. In the report of WGMS, after 1980’s the <span class="hlt">glacier</span> mass balance, in the Europe Alps and the Alaska region are decreases, and in Scandinavia region are increases. On the other hand, the <span class="hlt">glacier</span> mass balance in the Russia Altai Mountains located in Central Asia has the little change after 1980’s. These are research using the long-term observational data of Russian region of western part of Altai Mountains. The Altai Mountains including Russia, China, and Mongolia Kazakhstan, and there are description to a World <span class="hlt">Glacier</span> Inventory (WGI) about the <span class="hlt">glaciers</span> of Russia, China and Kazakhstan area, but the <span class="hlt">glaciers</span> of a Mongolian area, there are no description to the WGI. There is almost no information on the <span class="hlt">glacier</span> of a Mongolian Altai region, and there are many unknown points about <span class="hlt">glacier</span> change of the whole Altai Mountain region. In this research, while research clarified the present condition of <span class="hlt">glacier</span> distribution of the Mongolia Altai region, the actual condition of a <span class="hlt">glacier</span> change in recent years was clarified by comparison with the past topographical map. In this research, the <span class="hlt">glacier</span> area was distinguished based on the satellite image of the Mongolian <span class="hlt">glacier</span> regions. The used satellite image were 17 Landsat 7 ETM+ in 1999 to 2002. The <span class="hlt">glacier</span> distinguishes using NDSI (Normalized Difference Snow Index) indexusing Band5 and Band2. The topographical map of the Mongolian area was got based on the distribution information on this satellite <span class="hlt">glacier</span> area. The topographical map is 1/100,000 which</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C13B0440S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C13B0440S"><span>Lacustrine Records of Holocene Mountain <span class="hlt">Glacier</span> Fluctuations from Western Greenland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schweinsberg, A.; Briner, J. P.; Bennike, O.</p> <p>2014-12-01</p> <p> with cosmogenic 10Be exposure dating to further constrain the timing of deglaciation. In addition, these sedimentary archives will continue to be compared to radiocarbon dates of ice-killed vegetation along <span class="hlt">adjacent</span> ice cap margins to determine if times of persistent snowline lowering are correlative to periods of <span class="hlt">glacier</span> advance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70142330','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70142330"><span>Unusually loud ambient noise in tidewater <span class="hlt">glacier</span> fjords: a signal of ice melt</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Pettit, Erin C.; Lee, Kevin M.; Brann, Joel P.; Nystuen, Jeffrey A.; Wilson, Preston S.; O'Neel, Shad</p> <p>2015-01-01</p> <p>In <span class="hlt">glacierized</span> fjords, the ice-ocean boundary is a physically and biologically dynamic environment that is sensitive to both <span class="hlt">glacier</span> flow and ocean circulation. Ocean ambient noise offers insight into processes and change at the ice-ocean boundary. Here we characterize fjord ambient noise and show that the average noise levels are louder than nearly all measured natural oceanic environments (significantly louder than sea ice and <span class="hlt">non-glacierized</span> fjords). Icy Bay, Alaska has an annual average sound pressure level of 120 dB (re 1 μPa) with a broad peak between 1000 and 3000 Hz. Bubble formation in the water column as <span class="hlt">glacier</span> ice melts is the noise source, with variability driven by fjord circulation patterns. Measurements from two additional fjords, in Alaska and Antarctica, support that this unusually loud ambient noise in Icy Bay is representative of <span class="hlt">glacierized</span> fjords. These high noise levels likely alter the behavior of marine mammals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000JGR...10521295H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000JGR...10521295H"><span>Spectral roughness of glaciated bedrock geomorphic surfaces: Implications for <span class="hlt">glacier</span> sliding</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hubbard, Bryn; Siegert, Martin J.; McCarroll, Danny</p> <p>2000-09-01</p> <p>A microroughness meter (MRM) was used to measure the high-frequency roughness of a number of geomorphic surfaces in the forefield of <span class="hlt">Glacier</span> de Tsanfleuron, Switzerland. Resulting spectral power densities are added to low-frequency spectra, measured by electro-optical distance meter (EDM), to generate composite roughness spectra that include almost 5 orders of magnitude of roughness in the frequency domain. These are used to define two roughness indices: a general index of bed roughness is defined as the integral of the raw, spectral power densities, and a sliding-related index of bed roughness is defined as the integral of the spectral power densities weighted to account for the optimum dependence of <span class="hlt">glacier</span> sliding speed on hummock wavelength. Results indicate that MRM-measured geomorphic components vary in roughness by 3 orders of magnitude, principally depending on the surface microenvironment measured and profile orientation relative to the direction of former ice flow. Both MRM- and EDM-measured roughnesses are lower parallel to the direction of former ice flow than perpendicular to it. Composite roughness spectra consequently indicate that the <span class="hlt">glacier</span> bed is smoothed in the direction of former ice flow at all horizontal scales from 1 mm to 40 m, typically resulting in an order of magnitude decrease in sliding-related roughness relative to that measured perpendicular to ice flow. Comparison of data from two survey sites located <span class="hlt">adjacent</span> to, and ˜1.2 km from, the current <span class="hlt">glacier</span> margin indicates that postglacial subaerial weathering homogenizes bedrock roughness, in particular reducing high-frequency, flow-orthogonal roughness. Accounting for the effect of 28% ice-bedrock separation over one of the profiles reduces net, sliding-dependent roughness by between 27% and 43%, depending on the transition wave number used.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFMGC21A0731D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFMGC21A0731D"><span>Energy Balance and Hydrological Modelling of Zongo <span class="hlt">Glacier</span>, Bolivia, Using ERA-40 Reanalysis Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Duguay, M.; Hock, R.; Sicart, J.; Coudrain, A.</p> <p>2008-12-01</p> <p>In the Andes several regions profit significantly from glacial melt water for drink water supply and electricity production. During the dry season, <span class="hlt">glacier</span> melt is significant source of water in the semi-arid region of La Paz, Bolivia. The Andean <span class="hlt">glaciers</span> are retreating and water resources after reaching a culmination, will decrease. This implicates serious environmental and socio-economical consequences. For an effective attenuation, it is crucial to furnish quantitative predictions of the <span class="hlt">glacier</span> mass loss and its effects on the water resources in these regions. A distributed energy balance model has been developed to model mass balance and melt induced discharge of tropical <span class="hlt">glaciers</span>. We want to predict the changes in <span class="hlt">glacier</span> melt discharge in response to future climate change for the region of La Paz, Bolivia and later regionalize the model to a larger area. The model operates on daily steps, has a 20 m grid resolution, and is forced by daily data of air temperature, humidity, wind speed, global radiation and precipitation. As a test <span class="hlt">basin</span>, we calibrate the model at Glaciar Zongo, Bolivia, 16°15'S , 68°°10'W which is monitored by the French Institute for Research for the Development (IRD) . Zongo <span class="hlt">Glacier</span> is a 1,8 km2 large and the catchment is 63% <span class="hlt">glacierized</span>. Mass balance, weather station and discharge data are available on daily basis from 1991 onward. The measurements have gaps and only two years (1994-95 and 1999-00) with continuous data are available. In order to allow for multi-year simulations we force the model by daily ERA-40 reanalysis data from the European Center for Weather Forecast (ECMWF). To downscale the data we compare the daily data 1991-2002 to the observations at the <span class="hlt">glacier</span>. Results indicate a fair agreement for air temperature, but a rather poor correlation between the ERA-40 data and the observations for wind speed, global radiation and precipitation. The correlation is improved using monthly values. So far, test runs of the model</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFMIN41A0066R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMIN41A0066R"><span>The GLIMS <span class="hlt">Glacier</span> Database</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raup, B. H.; Khalsa, S. S.; Armstrong, R.</p> <p>2007-12-01</p> <p>The Global Land Ice Measurements from Space (GLIMS) project has built a geospatial and temporal database of <span class="hlt">glacier</span> data, composed of <span class="hlt">glacier</span> outlines and various scalar attributes. These data are being derived primarily from satellite imagery, such as from ASTER and Landsat. Each "snapshot" of a <span class="hlt">glacier</span> is from a specific time, and the database is designed to store multiple snapshots representative of different times. We have implemented two web-based interfaces to the database; one enables exploration of the data via interactive maps (web map server), while the other allows searches based on text-field constraints. The web map server is an Open Geospatial Consortium (OGC) compliant Web Map Server (WMS) and Web Feature Server (WFS). This means that other web sites can display <span class="hlt">glacier</span> layers from our site over the Internet, or retrieve <span class="hlt">glacier</span> features in vector format. All components of the system are implemented using Open Source software: Linux, PostgreSQL, PostGIS (geospatial extensions to the database), MapServer (WMS and WFS), and several supporting components such as Proj.4 (a geographic projection library) and PHP. These tools are robust and provide a flexible and powerful framework for web mapping applications. As a service to the GLIMS community, the database contains metadata on all ASTER imagery acquired over <span class="hlt">glacierized</span> terrain. Reduced-resolution of the images (browse imagery) can be viewed either as a layer in the MapServer application, or overlaid on the virtual globe within Google Earth. The interactive map application allows the user to constrain by time what data appear on the map. For example, ASTER or <span class="hlt">glacier</span> outlines from 2002 only, or from Autumn in any year, can be displayed. The system allows users to download their selected <span class="hlt">glacier</span> data in a choice of formats. The results of a query based on spatial selection (using a mouse) or text-field constraints can be downloaded in any of these formats: ESRI shapefiles, KML (Google Earth), Map</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=Are+AND+original+AND+AJ+AND+Quartmain+AND++AND+Michaels+AND+real+AND+Bio+AND+dad+AND+k&pg=4&id=EJ1151507','ERIC'); return false;" href="https://eric.ed.gov/?q=Are+AND+original+AND+AJ+AND+Quartmain+AND++AND+Michaels+AND+real+AND+Bio+AND+dad+AND+k&pg=4&id=EJ1151507"><span><span class="hlt">Non-Adjacent</span> Consonant Sequence Patterns in English Target Words during the First-Word Period</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Aoyama, Katsura; Davis, Barbara L.</p> <p>2017-01-01</p> <p>The goal of this study was to investigate <span class="hlt">non-adjacent</span> consonant sequence patterns in target words during the first-word period in infants learning American English. In the spontaneous speech of eighteen participants, target words with a Consonant-Vowel-Consonant (C[subscript 1]VC[subscript 2]) shape were analyzed. Target words were grouped into…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813607V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813607V"><span>Detecting <span class="hlt">glacier</span>-bed overdeepenings for <span class="hlt">glaciers</span> in the Western Italian Alps using the GlabTop2 model: the test site of the Rutor <span class="hlt">Glacier</span>, Aosta Valley</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Viani, Cristina; Machguth, Horst; Huggel, Christian; Perotti, Luigi; Giardino, Marco</p> <p>2016-04-01</p> <p>It is expected that the rapid retreat of <span class="hlt">glaciers</span>, observed in the European Alps and other mountain regions of the world, will continue in the future. One of the most evident and relevant consequences of this phenomenon is the formation of new <span class="hlt">glacier</span> lakes in recently deglaciated areas. During <span class="hlt">glacier</span> retreat overdeepened parts of the <span class="hlt">glacier</span> bed become exposed and, in some cases, filled with water. It is important to understand where these new lakes can appear because of the associated potential risks (i.e. lake outburst and consequent flood) and opportunities (tourism, hydroelectricity, water reservoir, etc.) especially in densely populated areas such as the European Alps. GlabTop2 (<span class="hlt">Glacier</span> Bed Topography model version 2) allows to model <span class="hlt">glacier</span> bed topography over large glaciated areas combining digital terrain information and slope-related estimates of <span class="hlt">glacier</span> thickness. The model requires a minimum set of input data: <span class="hlt">glaciers</span> outlines and a surface digital elevation model (DEM). In this work we tested the model on the Rutor <span class="hlt">Glacier</span> (8,1 km2) located in the Aosta Valley. The <span class="hlt">glacier</span> has a well-known history of a series of <span class="hlt">glacier</span> lake outburst floods between 1430 AD and 1864 AD due to front fluctuations. After the last advance occurred during the 70s of the previous century, <span class="hlt">glacier</span> shrinkage has been continuous and new lakes have formed in newly exposed overdeepenings. We applied GlabTop2 to DEMs derived from historical data (topographic maps and aerial photos pair) representing conditions before the proglacial lake formation. The results obtained have been compared with the present situation and existing lakes. Successively we used the model also on present-day DEMs, which are of higher resolution than the historical derived ones, and compared the modeled bed topography with an existing bedrock map obtained by in-situ geophysical investigations (GPR surveys). Preliminary results, obtained with the 1991 surface model, confirm the robustness of GlabTop2 in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.C13D0872J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.C13D0872J"><span>Monitoring Jakobshavn <span class="hlt">Glacier</span> using Sequential Landsat Images</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jian, Z.; Zhuoqi, C.; Cheng, X.</p> <p>2016-12-01</p> <p>Jakobshavn <span class="hlt">Glacier</span> is the fastest (19 m per day) and one of the most active <span class="hlt">glaciers</span> around the world. Discharging more than 35km3 of ice every year, its mass loss surpasses anyone else outside the Antarctic. From Landsat 8 OLI Images on August 14, 2015, we find a huge iceberg about 5 km2 calved from resulting in the front shrinking for 1060.8m. NSIDC ice velocity data and weather station data on Jakobshavn <span class="hlt">glacier</span> are used to analyze the cause of calving. On one hand, upstream <span class="hlt">glacier</span> push forward the Jakobshavn <span class="hlt">glacier</span> westward continually, many cracks were formed over the <span class="hlt">glacier</span> surface. Surface melting water flow into the interior of <span class="hlt">glaciers</span> to accelerate calving. On the other hand with the gradually rising temperature, the bottom of <span class="hlt">glaciers</span> accelerate ablation. When <span class="hlt">glaciers</span> move into the ocean and the thin bottom can not provide strong enough support, calving occurs. Before this incident, we trace sequential Landsat data during 1986 to 2015. In 2010, it had another large-scale calving. We draw from our data that Jakobshavn retreated intensely in the past 30 years although in the last 10 years it appears more stable. The speed of <span class="hlt">glacier</span> shrinking during 1996 to 2006 is three times as fast as past 10 years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EOSTr..93..212K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EOSTr..93..212K"><span><span class="hlt">Glaciers</span> in Patagonia: Controversy and prospects</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kargel, J. S.; Alho, P.; Buytaert, W.; Célleri, R.; Cogley, J. G.; Dussaillant, A.; Guido, Z.; Haeberli, W.; Harrison, S.; Leonard, G.; Maxwell, A.; Meier, C.; Poveda, G.; Reid, B.; Reynolds, J.; Rodríguez, C. A. Portocarrero; Romero, H.; Schneider, J.</p> <p>2012-05-01</p> <p>Lately, <span class="hlt">glaciers</span> have been subjects of unceasing controversy. Current debate about planned hydroelectric facilities—a US7- to 10-billion megaproject—in a pristine <span class="hlt">glacierized</span> area of Patagonia, Chile [Romero Toledo et al., 2009; Vince, 2010], has raised anew the matter of how glaciologists and global change experts can contribute their knowledge to civic debates on important issues. There has been greater respect for science in this controversy than in some previous debates over projects that pertain to <span class="hlt">glaciers</span>, although valid economic motivations again could trump science and drive a solution to the energy supply problem before the associated safety and environmental problems are understood. The connection between <span class="hlt">glaciers</span> and climate change—both anthropogenic and natural—is fundamental to glaciology and to <span class="hlt">glaciers</span>' practical importance for water and hydropower resources, agriculture, tourism, mining, natural hazards, ecosystem conservation, and sea level [Buytaert et al., 2010; Glasser et al., 2011]. The conflict between conservation and development can be sharper in <span class="hlt">glacierized</span> regions than almost anywhere else. <span class="hlt">Glaciers</span> occur in spectacular natural landscapes, but they also supply prodigious exploitable meltwater.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/7184033-glacier-recession-iceland-austria','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/7184033-glacier-recession-iceland-austria"><span><span class="hlt">Glacier</span> recession in Iceland and Austria</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Hall, D.K.; Williams, R.S. Jr.; Bayr, K.J.</p> <p>1992-03-01</p> <p>It has been possible to measure <span class="hlt">glacier</span> recession on the basis of Landsat data, in conjunction with comparisons of the magnitude of recession of a <span class="hlt">glacier</span> margin with in situ measurements at fixed points along the same margin. Attention is presently given to the cases of Vatnajokull ice cap, in Iceland, and the Pasterze <span class="hlt">Glacier</span>, in Austria, on the basis of satellite data from 1973-1987 and 1984-1990, respectively. Indications of a trend toward negative mass balance are noted. Nevertheless, while most of the world's small <span class="hlt">glaciers</span> have been receding, some are advancing either due to local climate or the tidewatermore » <span class="hlt">glacier</span> cycle. 21 refs.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018HESS...22..463V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018HESS...22..463V"><span>The role of <span class="hlt">glacier</span> changes and threshold definition in the characterisation of future streamflow droughts in glacierised catchments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Van Tiel, Marit; Teuling, Adriaan J.; Wanders, Niko; Vis, Marc J. P.; Stahl, Kerstin; Van Loon, Anne F.</p> <p>2018-01-01</p> <p><span class="hlt">Glaciers</span> are essential hydrological reservoirs, storing and releasing water at various timescales. Short-term variability in <span class="hlt">glacier</span> melt is one of the causes of streamflow droughts, here defined as deficiencies from the flow regime. Streamflow droughts in glacierised catchments have a wide range of interlinked causing factors related to precipitation and temperature on short and long timescales. Climate change affects <span class="hlt">glacier</span> storage capacity, with resulting consequences for discharge regimes and streamflow drought. Future projections of streamflow drought in glacierised <span class="hlt">basins</span> can, however, strongly depend on the modelling strategies and analysis approaches applied. Here, we examine the effect of different approaches, concerning the <span class="hlt">glacier</span> modelling and the drought threshold, on the characterisation of streamflow droughts in glacierised catchments. Streamflow is simulated with the Hydrologiska Byråns Vattenbalansavdelning (HBV-light) model for two case study catchments, the Nigardsbreen catchment in Norway and the Wolverine catchment in Alaska, and two future climate change scenarios (RCP4.5 and RCP8.5). Two types of <span class="hlt">glacier</span> modelling are applied, a constant and dynamic <span class="hlt">glacier</span> area conceptualisation. Streamflow droughts are identified with the variable threshold level method and their characteristics are compared between two periods, a historical (1975-2004) and future (2071-2100) period. Two existing threshold approaches to define future droughts are employed: (1) the threshold from the historical period; (2) a transient threshold approach, whereby the threshold adapts every year in the future to the changing regimes. Results show that drought characteristics differ among the combinations of <span class="hlt">glacier</span> area modelling and thresholds. The historical threshold combined with a dynamic <span class="hlt">glacier</span> area projects extreme increases in drought severity in the future, caused by the regime shift due to a reduction in <span class="hlt">glacier</span> area. The historical threshold combined with a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..4312466K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..4312466K"><span>Contemporary <span class="hlt">glacier</span> retreat triggers a rapid landslide response, Great Aletsch <span class="hlt">Glacier</span>, Switzerland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kos, Andrew; Amann, Florian; Strozzi, Tazio; Delaloye, Reynald; Ruette, Jonas; Springman, Sarah</p> <p>2016-12-01</p> <p>The destabilization and catastrophic failure of landslides triggered by retreating <span class="hlt">glaciers</span> is an expected outcome of global climate change and poses a significant threat to inhabitants of glaciated mountain valleys around the globe. Of particular importance are the formation of landslide-dammed lakes, outburst floods, and related sediment entrainment. Based on field observations and remote sensing of a deep-seated landslide, located at the present-day terminus of the Great Aletsch <span class="hlt">Glacier</span>, we show that the spatiotemporal response of the landslide to <span class="hlt">glacier</span> retreat is rapid, occurring within a decade. Our observations uniquely capture the critical period of increase in slope deformations, onset of failure, and show that measured displacements at the crown and toe regions of the landslide demonstrate a feedback mechanism between <span class="hlt">glacier</span> ice reduction and response of the entire landslide body. These observations shed new light on the geomorphological processes of landslide response in paraglacial environments, which were previously understood to occur over significantly longer time periods.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011TCD.....5.3423D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011TCD.....5.3423D"><span>Seasonal speed-up of two outlet <span class="hlt">glaciers</span> of Austfonna, Svalbard, inferred from continuous GPS measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dunse, T.; Schuler, T. V.; Hagen, J. O.; Reijmer, C. H.</p> <p>2011-12-01</p> <p>A large part of the ice discharge from ice caps and ice sheets occurs through spatially limited flow units that may operate in a mode of steady flow or cyclic surge behaviour. Changes in the dynamics of distinct flow units play a key role in the mass balance of Austfonna, the largest ice cap on Svalbard. The recent net mass loss of Austfonna was dominated by calving from marine terminating outlet <span class="hlt">glaciers</span>. Previous ice-surface velocity maps of the ice cap were derived by satellite radar interferometry (InSAR) and rely on data acquired in the mid-1990s with limited information concerning the temporal variability. Here, we present continuous Global Positioning System (GPS) observations along the central flowlines of two fast flowing outlet <span class="hlt">glaciers</span> over 2008-2010. The data show prominent summer speed-ups with ice-surface velocities as high as 240 % of the pre-summer mean. Acceleration follows the onset of the summer melt period, indicating enhanced basal motion due to input of surface meltwater into the subglacial drainage system. In 2008, multiple velocity peaks coincide with successive melt periods. In 2009, the principle melt was of higher amplitude than in 2008. Flow velocities appear unaffected by subsequent melt periods, suggesting a transition towards a hydraulically more efficient drainage system. The observed annual mean velocities of Duvebreen and <span class="hlt">Basin</span>-3 exceed those from the mid-1990s by factors two and four, respectively, implying increased ice discharge at the calving front. Measured summer velocities up to 2 m d-1 for <span class="hlt">Basin</span>-3 are close to that of Kronebreen, often referred to as the fastest <span class="hlt">glacier</span> on Svalbard.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001479.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001479.html"><span><span class="hlt">Glaciers</span> and Sea Level Rise</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-08</p> <p>This ice cave in Belcher <span class="hlt">Glacier</span> (Devon Island, Canada) was formed by melt water flowing within the <span class="hlt">glacier</span> ice. To learn about the contributions of <span class="hlt">glaciers</span> to sea level rise, visit: www.nasa.gov/topics/earth/features/<span class="hlt">glacier</span>-sea-rise.html Credit: Angus Duncan, University of Saskatchewan NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730010647','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730010647"><span>Evaluate ERTS imagery for mapping and detection of changes of snowcover on land and on <span class="hlt">glaciers</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Meier, M. F. (Principal Investigator)</p> <p>1973-01-01</p> <p>The author has identified the following significant results. The percentage of snow cover area on specific drainage <span class="hlt">basins</span> was measured from ERTS-1 imagery by video density slicing with a repeatability of 4 percent of the snow covered area. Data from ERTS-1 images of the melt season snow cover in the Thunder Creek drainage <span class="hlt">basin</span> in the North Cascades were combined with existing hydrologic and meteorologic observations to enable calculations of the time distribution of the water stored in this mountain snowpack. Similar data could be used for frequent updating of expected inflow to reservoirs. Equivalent snowline altitudes were determined from area measurements. Snowline altitudes were also determined by combining enlarged ERTS-1 images with maps. ERTS-1 imagery was also successfully used to measure <span class="hlt">glacier</span> accumulation area ratios for a small test <span class="hlt">basin</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70021223','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70021223"><span>Seasonal variability in hydrologic-system response to intense rain events, Matanuska <span class="hlt">Glacier</span>, Alaska, U.S.A.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Denner, J.C.; Lawson, D.E.; Larson, G.J.; Evenson, E.B.; Alley, R.B.; Strasser, J.C.; Kopczynski, S.</p> <p>1999-01-01</p> <p>Two rain events at Matanuska <span class="hlt">Glacier</span> illustrate how subglacial drainage system development and snowpack conditions affect hydrologic response at the terminus. On 21 and 22 September 1995, over 56 mm of rain fell in the <span class="hlt">basin</span> during a period usually characterized by much drier conditions. This event caused an 8-fold increase in discharge and a 47-fold increase in suspended-sediment concentration. Peak suspended-sediment concentration exceeded 20 kg m-3, suggesting rapid evacuation of stored sediment. While water discharge returned to its pre-storm level nine days after the rain ceased, suspended-sediment concentrations took about 20 days to return to pre-storm levels. These observations suggest that the storm influx late in the melt season probably forced subglacial water into a more distributed system. In addition, subglacially transported sediments were supplemented to an unknown degree by the influx of storm-eroded sediments off hillslopes and from tributary drainage <span class="hlt">basins</span>. A storm on 6 and 7 June 1997, dropped 28 mm of rain on the <span class="hlt">basin</span> demonstrating the effects of meltwater retention in the snowpack and englacial and subglacial storage early in the melt season. Streamflow before the storm event was increasing gradually owing to warming temperatures; however, discharge during the storm and the following week increased only slightly. Suspended-sediment concentrations increased only a small amount, suggesting the drainage system was not yet well developed, and much of the runoff occurred across the relatively clean surface of the <span class="hlt">glacier</span> or through englacial channels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C41B1200Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C41B1200Q"><span>Quantifying the Mass Flux, Erosion Rates and Geomorphological Impact of Surging Karakoram <span class="hlt">Glaciers</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Quincey, D. J.; Glasser, N. F.; King, O.</p> <p>2017-12-01</p> <p>Surge-type <span class="hlt">glaciers</span> switch between phases of rapid and slow flow on timescales of a few years to decades. Here, we describe <span class="hlt">glacier</span>-surface debris changes, surface-elevation changes and velocity changes through surges lasting five to ten years on ten different Karakoram <span class="hlt">glaciers</span> (Khurdopin, Gasherbrum, Kunyang, Braldu, Chong Khumdan, Qiogeli, Saxintulu, Shakesiga, Skamri and Unnamed). We use these data to characterise their geomorphological imprint on the landscape, calculate a minimum mass flux for each of the surges and provide first-order estimates of bed erosion rates. Surface debris transport through the surges includes widespread rearrangement of surface debris features, folding and the concentration of debris near <span class="hlt">glacier</span> termini, confluences and margins. Ice and debris-flux is partly dependent on the style of the surge, and in particular whether a surge-front propagates down-<span class="hlt">glacier</span> during the active phase. Erosion rates also depend on the style and longevity of the surge, but are largely comparable between each of the studied datasets. We conclude by estimating the geomorphic work undertaken during surge events in comparison to work carried out by <span class="hlt">non</span>-surging <span class="hlt">glaciers</span> in the same region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.C23A0646L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.C23A0646L"><span><span class="hlt">Glacier</span> changes in the Chinese Karakoram-Himalaya Mountains since the late 1950s as revealed by inventories from topographical maps and satellite images</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, S.; Guo, W.; Wei, J.; Bao, W.</p> <p>2012-12-01</p> <p>The Karakoram-Himalaya Mountains (KHM) are the largest mountain system surrounding the Tibetan Plateau. The early and the recent estimate indicate that the total <span class="hlt">glacier</span> area in KHM region is about one third of that in the whole Asia High Mountains. <span class="hlt">Glaciers</span> in KHM are one of the key components in the water resource formation and variation of rivers like Tarim, Brahmaputra, Indus, and Ganges, and so on, where about 1 billion people are living in. Climate change have led to retreating of <span class="hlt">glaciers</span> in the ranges which may have potential impact on the water availability and so the food and water resources security in the lower reaches of river <span class="hlt">basins</span> that originated from the huge mountains. Lot of efforts have been taken for understanding changes of <span class="hlt">glaciers</span> in the region, but few covers the changes based on <span class="hlt">glacier</span> inventories. Here we introduce our results for <span class="hlt">glaciers</span> in Chinese part based on <span class="hlt">glacier</span> inventories from the topographical maps in the late 1950s to early 1980s (area average year of 1972 in the Karakoram and 1975 in the Himalaya) and from satellite images (Landsat TM/ETM+, ASTER, SPOT4/5) acquired in 2009/2010. By excluding those <span class="hlt">glaciers</span> not well identified from optical images, the total area of <span class="hlt">glaciers</span> mapped for the second time are 89% and 69% of the total ones mapped at first time in the Karakoram and Himalaya mountains. Results show that <span class="hlt">glacier</span> retreat was dominant and very few <span class="hlt">glaciers</span> were in advance or stable. <span class="hlt">Glaciers</span> in the Himalaya have lost 26.3% of their area in the late 1950s to early 1980s, while that in the Karakoram is 11.9% for the similar time span. As far annual retreat rates, <span class="hlt">glaciers</span> in Himalaya have experienced a speedy area decrease by 0.80%/yr, higher than that of 0.33%/yr in Karakorum. In General, <span class="hlt">glacier</span> shrinkage in KHM shows obvious spatial heterogeneity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/prof/p1386b/','USGSPUBS'); return false;" href="https://pubs.usgs.gov/prof/p1386b/"><span><span class="hlt">Glaciers</span> of Antarctica</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Williams, Richard S.; Ferrigno, Jane G.</p> <p>1988-01-01</p> <p>Of all the world?s continents Antarctica is the coldest, the highest, and the least known. It is one and a half times the size of the United States, and on it lies 91 percent (30,109,800 km3) of the estimated volume of all the ice on Earth. Because so little is known about Antarctic <span class="hlt">glaciers</span> compared with what is known about <span class="hlt">glaciers</span> in populated countries, satellite imagery represents a great leap forward in the provision of basic data. From the coast of Antarctica to about 81?south latitude, there are 2,514 Landsat nominal scene centers (the fixed geographic position of the intersection of orbital paths and latitudinal rows). If there were cloud-free images for all these geographic centers, only about 520 Landsat images would be needed to provide complete coverage. Because of cloud cover, however, only about 70 percent of the Landsat imaging area, or 55 percent of the continent, is covered by good quality Landsat images. To date, only about 20 percent of Antarctica has been mapped at scales of 1:250,000 or larger, but these maps do include about half of the coastline. The area of Antarctica that could be planimetrically mapped at a scale of 1:250,000 would be tripled if the available Landsat images were used in image map production. This chapter contains brief descriptions and interpretations of features seen in 62 carefully selected Landsat images or image mosaics. Images were chosen on the basis of quality and interest; for this reason they are far from evenly spaced around the continent. Space limitations allow less than 15 percent of the Landsat imaging area of Antarctica to be shown in the illustrations reproduced in this chapter. Unfortunately, a wealth of glaciological and other features of compelling interest is present in the many hundreds of images that could not be included. To help show some important features beyond the limit of Landsat coverage, and as an aid to the interpretation of certain features seen in the images, 38 oblique aerial photographs</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JHyd..521...46K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JHyd..521...46K"><span>Separating snow, clean and debris covered ice in the Upper Indus <span class="hlt">Basin</span>, Hindukush-Karakoram-Himalayas, using Landsat images between 1998 and 2002</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khan, Asif; Naz, Bibi S.; Bowling, Laura C.</p> <p>2015-02-01</p> <p>The Hindukush Karakoram Himalayan mountains contain some of the largest <span class="hlt">glaciers</span> of the world, and supply melt water from perennial snow and <span class="hlt">glaciers</span> to the Upper Indus <span class="hlt">Basin</span> (UIB) upstream of Tarbela dam, which constitutes greater than 80% of the annual flows, and caters to the needs of millions of people in the Indus <span class="hlt">Basin</span>. It is therefore important to study the response of perennial snow and <span class="hlt">glaciers</span> in the UIB under changing climatic conditions, using improved hydrological modeling, <span class="hlt">glacier</span> mass balance, and observations of <span class="hlt">glacier</span> responses. However, the available <span class="hlt">glacier</span> inventories and datasets only provide total perennial-snow and <span class="hlt">glacier</span> cover areas, despite the fact that snow, clean ice and debris covered ice have different melt rates and densities. This distinction is vital for improved hydrological modeling and mass balance studies. This study, therefore, presents a separated perennial snow and <span class="hlt">glacier</span> inventory (perennial snow-cover on steep slopes, perennial snow-covered ice, clean and debris covered ice) based on a semi-automated method that combines Landsat images and surface slope information in a supervised maximum likelihood classification to map distinct <span class="hlt">glacier</span> zones, followed by manual post processing. The accuracy of the presented inventory falls well within the accuracy limits of available snow and <span class="hlt">glacier</span> inventory products. For the entire UIB, estimates of perennial and/or seasonal snow on steep slopes, snow-covered ice, clean and debris covered ice zones are 7238 ± 724, 5226 ± 522, 4695 ± 469 and 2126 ± 212 km2 respectively. Thus total snow and <span class="hlt">glacier</span> cover is 19,285 ± 1928 km2, out of which 12,075 ± 1207 km2 is <span class="hlt">glacier</span> cover (excluding steep slope snow-cover). Equilibrium Line Altitude (ELA) estimates based on the Snow Line Elevation (SLE) in various watersheds range between 4800 and 5500 m, while the Accumulation Area Ratio (AAR) ranges between 7% and 80%. 0 °C isotherms during peak ablation months (July and August) range</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15..930L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15..930L"><span>Radio-echo sounding of Caucasus <span class="hlt">glaciers</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lavrentiev, Ivan; Kutuzov, Stanislav; Vasilenko, Evgeny; Macheret, Yuri</p> <p>2013-04-01</p> <p>Accurate <span class="hlt">glacier</span> volume and ice-thickness estimations are highly important for many glaciological applications. Recent <span class="hlt">glacier</span> reduction is affecting local river discharge and contributes to the global sea level rise. However, direct measurements of ice thickness are very sparse due to its high cost and laboriousness. One of the <span class="hlt">glacierized</span> mountain regions with a lack of direct ice-thickness measurements is Caucasus. So far data for several seismic and GPR profiles have been reported for only 3 <span class="hlt">glaciers</span> from more than 1.7 thousands located in Caucasus. In 2010-2012 a number of ground base and airborne radio-echo sounding surveys have been accomplished in Caucasus Mountains using 20 MHz monopulse radar VIRL-6. Special aerial version of this ground penetrating radar was designed for helicopter-born measurements. The radar has a relatively long (10 m) receiving and transmitting antennas, which together with receiving, recording and transmitting devices can be mounted on a special girder, being suspended from a helicopter. VIRL-6 radar is light weight and can be quickly transformed into ground version. Equipment has been used on 16 <span class="hlt">glaciers</span> including biggest <span class="hlt">glacier</span> in Caucasus - Bezengi (36 km2) most of which have a highly crevassed surfaces and heterogeneous internal structure. Independent data were obtained also for two <span class="hlt">glaciers</span> using ground version of the same VIRL-6 radar. In total more than 120 km of radar profiles were obtained. Results showed good agreement between ground and aerial measurements. Ice-thickness values exceeded 420 m for some of the Central Caucasus <span class="hlt">glaciers</span>. Successful use of VIRL-6 radar in Caucasus opens up the possibility of using such equipment on different types of <span class="hlt">glaciers</span> in polar and mountain regions, including temperate, polythermal and surging <span class="hlt">glaciers</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.H13L1589M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.H13L1589M"><span>Hydrochemical Signatures of <span class="hlt">Glacier</span> Melt and Groundwater Storage on Volcán Chimborazo, Ecuador</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McLaughlin, R.; Ng, G. H. C.; La Frenierre, J.; Wickert, A. D.; Baraer, M.</p> <p>2016-12-01</p> <p>With ever-growing water demands for hydroelectricity, agriculture, and domestic use, the accelerated retreat of tropical <span class="hlt">glaciers</span> is raising concerns about future water supply sustainability. In the tropical Andes, where precipitation is seasonal and spatially heterogeneous, <span class="hlt">glaciers</span> are particularly important as their storage and slow release of water helps to modulate stream discharge on daily to yearly time scales. Predicting the effect their shrinkage will have on water resources is not straightforward as little is known about the connections in these glaciated volcanic catchments between meltwater, groundwater, precipitation and surficial discharge. Here, stable isotope and major ion analyses inform a hydrochemical mixing model in order to identify water sources and their relative contributions to stream and spring discharge on Volcán Chimborazo, a stratovolcano located in the Ecuadorian Andes. Moisture in this region generally arrives from the Amazon <span class="hlt">basin</span> to the east, resulting in a steep northeast-southwest precipitation gradient that produces wet and dry sides of the mountain. Dry season water samples were collected on both sides from major streams and springs at varying elevations and distances from the <span class="hlt">glacier</span> tongues, along with samples of precipitation (when possible) and <span class="hlt">glacier</span> ice. Data on specific conductivity, pH, and temperature were collected in situ for each sample. The paired catchment study allows us to isolate a primarily glacial melt signature on the dry side and compare it to data on the wet side, where glacial melt and precipitation both contribute to groundwater and surface-water discharge.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70197253','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70197253"><span>Reconnaissance stratigraphy of the Red <span class="hlt">Glacier</span> Formation (Middle Jurassic) near Hungryman Creek, Cook Inlet <span class="hlt">basin</span>, Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>LePain, D.L.; Stanley, Richard G.; Helmold, K.P.</p> <p>2016-01-01</p> <p>Geochemical data suggest the source of oil in upper Cook Inlet fields is Middle Jurassic organic-rich shales in the Tuxedni Group (Magoon and Anders, 1992; Lillis and Stanley, 2011; LePain and others, 2012, 2013). Of the six formations in the group (Detterman, 1963), the basal Red <span class="hlt">Glacier</span> Formation is the only unit that includes fine-grained rocks in outcrop that appear to be organic-rich (fig. 3-1). In an effort to better understand the stratigraphy and source-rock potential of the Red <span class="hlt">Glacier</span> Formation, the Alaska Division of Geological & Geophysical Surveys, in collaboration with the Alaska Division of Oil and Gas and the U.S. Geological Survey, has been investigating the unit in outcrop between Tuxedni Bay and the type section at Lateral and Red <span class="hlt">glaciers</span> (Stanley and others, 2013; LePain and Stanley, 2015; Helmold and others, 2016 [this volume]). Fieldwork in 2015 focused on a southeast-trending ridge south of Hungryman Creek, where the lower 60–70 percent of the formation (400–500 m) is exposed and accessible, except for the near-vertical faces of three segments near the southeast end of the ridge (figs. 3-2 and 3-3). Three stratigraphic sections were measured along the ridge to document facies and depositional environments (figs. 3-3 and 3-4). Steep terrain precluded study of the upper part of the formation exposed east of the ridge. This report includes a preliminary summary of findings from the 2015 field season.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1912332S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1912332S"><span>Geodetic <span class="hlt">glacier</span> mass balancing on ice caps - inseparably connected to firn modelling?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saß, Björn L.; Sauter, Tobias; Seehaus, Thorsten; Braun, Matthias H.</p> <p>2017-04-01</p> <p>Observed melting of <span class="hlt">glaciers</span> and ice caps in the polar regions contribute to the ongoing global sea level rise (SLR). A rising sea level and its consequences are one of the major challenges for coastal societies in the next decades to centuries. Gaining knowledge about the main drivers of SLR and bringing it together is one recent key-challenge for environmental science. The high arctic Svalbard archipelago faced a strong climatic change in the last decades, associated with a change in the cryosphere. Vestfonna, a major Arctic ice cap in the north east of Svalbard, harbors land and marine terminating <span class="hlt">glaciers</span>, which expose a variability of behavior. We use high resolution remote sensing data from space-borne radar (TanDEM-X, TerraSAR-X, Sentinel-1a), acquired between 2009 and 2015, to estimate <span class="hlt">glacier</span> velocity and high accurate surface elevation changes. For DEM registration we use space-borne laser altimetry (ICESat) and an existing in-situ data archive (IPY Kinnvika). In order to separate individual <span class="hlt">glacier</span> <span class="hlt">basin</span> changes for a detailed mass balance study and for further SLR contribution estimates, we use <span class="hlt">glacier</span> outlines from the Global Land Ice Measurements from Space (GLIMS) project. Remaining challenges of space-borne observations are the reduction of measurement uncertainties, in the case of Synthetic Aperture Radar most notably signal penetration into the <span class="hlt">glacier</span> surface. Furthermore, in order to convert volume to mass change one has to use the density of the changed mass (conversion factor) and one has to account for the mass conservation processes in the firn package (firn compaction). Both, the conversion factor and the firn compaction are not (yet) measurable for extensive ice bodies. They have to be modelled by coupling point measurements and regional gridded climate data. Results indicate a slight interior thickening contrasted with wide spread thinning in the ablation zone of the marine terminating outlets. While one <span class="hlt">glacier</span> system draining to the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150021199','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150021199"><span>An Integrated Modeling System for Estimating <span class="hlt">Glacier</span> and Snow Melt Driven Streamflow from Remote Sensing and Earth System Data Products in the Himalayas</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brown, M. E.; Racoviteanu, A. E.; Tarboton, D. G.; Sen Gupta, A.; Nigro, J.; Policelli, F.; Habib, S.; Tokay, M.; Shrestha, M. S.; Bajracharya, S.</p> <p>2014-01-01</p> <p>Quantification of the contribution of the hydrologic components (snow, ice and rain) to river discharge in the Hindu Kush Himalayan (HKH) region is important for decision-making in water sensitive sectors, and for water resources management and flood risk reduction. In this area, access to and monitoring of the <span class="hlt">glaciers</span> and their melt outflow is challenging due to difficult access, thus modeling based on remote sensing offers the potential for providing information to improve water resources management and decision making. This paper describes an integrated modeling system developed using downscaled NASA satellite based and earth system data products coupled with in-situ hydrologic data to assess the contribution of snow and <span class="hlt">glaciers</span> to the flows of the rivers in the HKH region. Snow and <span class="hlt">glacier</span> melt was estimated using the Utah Energy Balance (UEB) model, further enhanced to accommodate <span class="hlt">glacier</span> ice melt over clean and debris-covered tongues, then meltwater was input into the USGS Geospatial Stream Flow Model (Geo- SFM). The two model components were integrated into Better Assessment Science Integrating point and Nonpoint Sources modeling framework (<span class="hlt">BASINS</span>) as a user-friendly open source system and was made available to countries in high Asia. Here we present a case study from the Langtang Khola watershed in the monsoon-influenced Nepal Himalaya, used to validate our energy balance approach and to test the applicability of our modeling system. The snow and <span class="hlt">glacier</span> melt model predicts that for the eight years used for model evaluation (October 2003-September 2010), the total surface water input over the <span class="hlt">basin</span> was 9.43 m, originating as 62% from <span class="hlt">glacier</span> melt, 30% from snowmelt and 8% from rainfall. Measured streamflow for those years were 5.02 m, reflecting a runoff coefficient of 0.53. GeoSFM simulated streamflow was 5.31 m indicating reasonable correspondence between measured and model confirming the capability of the integrated system to provide a quantification</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C33E0866P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C33E0866P"><span>Sensitivity of annual mass balance gradient and Hypsometry to the changing climate: the case of Dokriani <span class="hlt">Glacier</span>, central Himalaya, India</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pratap, B.</p> <p>2015-12-01</p> <p>The <span class="hlt">glacier</span> mass balance is undelayed, unfiltered and direct method to assess the impact of climate change on the <span class="hlt">glaciers</span>. Many studies suggest that some of the Himalayan <span class="hlt">glaciers</span> have lost their mass at an increased rate during the past few decades. Furthermore, the mass balance gradient and hypsometric analysis are important to understand the <span class="hlt">glacier</span> response towards climatic perturbations. Our long term in-situ monitoring on the Dokriani <span class="hlt">Glacier</span> provides great insights to understand the variability in central Himalayan <span class="hlt">glaciers</span>. We report the relationship between <span class="hlt">glacier</span> hypsometry and annual mass balance gradient (12 years) to understand the <span class="hlt">glacier</span>'s response towards climate change. Dokriani <span class="hlt">Glacier</span> in the Bhagirathi <span class="hlt">basin</span> is a small (7 km2) NNW exposed <span class="hlt">glacier</span> in the western part of central Himalaya, India. The study analysed the annual balance, mass balance gradient and length changes observed during first decade of 21st century (2007-2013) and compare with the previous observations of 1990s (1992-2000). A large spatial variability in the mass balance gradients of two different periods has been observed. The equilibrium-line altitude (ELA) was fluctuated between 5000 and 5100 m a.s.l. and the derived time averaged ELA (ELAn) and balance budget ELA (ELA0) were 5075 and 4965 m a.s.l respectively during 1992-2013. The observed time-averaged accumulation-area ratio (AARn) and balance budget AAR (AAR0) were 0.67 and 0.72 respectively during 1992-2013. The higher value of AAR comprises due to flat and broader accumulation area (4.50 km2) of the <span class="hlt">glacier</span>. Although, having larger accumulation area, the <span class="hlt">glacier</span> has faced strong mass wasting with average annual ablation of -1.82 m w.e. a-1 in the ablation zone as compare to residual average annual accumulation of 0.41 m w.e. a-1. Based on the annual mass balance series (12 years) Dokriani <span class="hlt">Glacier</span> has continuous negative annual balances with monotonically negative cumulative mass loss of -3.86 m w.e with the average</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001874.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001874.html"><span>Malaspina <span class="hlt">Glacier</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-08</p> <p>NASA image captured August 31, 2000 The tongue of the Malaspina <span class="hlt">Glacier</span>, the largest <span class="hlt">glacier</span> in Alaska, fills most of this image. The Malaspina lies west of Yakutat Bay and covers 1,500 sq. MI (3,880 sq. km). Credit: NASA/Landsat NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17749022','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17749022"><span>Quantifying global warming from the retreat of <span class="hlt">glaciers</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Oerlemans, J</p> <p>1994-04-08</p> <p>Records of <span class="hlt">glacier</span> fluctuations compiled by the World <span class="hlt">Glacier</span> Monitoring Service can be used to derive an independent estimate of global warming during the last 100 years. Records of different <span class="hlt">glaciers</span> are made comparable by a two-step scaling procedure: one allowing for differences in <span class="hlt">glacier</span> geometry, the other for differences in climate sensitivity. The retreat of <span class="hlt">glaciers</span> during the last 100 years appears to be coherent over the globe. On the basis of modeling of the climate sensitivity of <span class="hlt">glaciers</span>, the observed <span class="hlt">glacier</span> retreat can be explained by a linear warming trend of 0.66 kelvin per century.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.water.usgs.gov/sir2004-5234/','USGSPUBS'); return false;" href="http://pubs.water.usgs.gov/sir2004-5234/"><span>Simulated peak inflows for <span class="hlt">glacier</span> dammed Russell Fiord, near Yakutat, Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Neal, Edward G.</p> <p>2004-01-01</p> <p>In June 2002, Hubbard <span class="hlt">Glacier</span> advanced across the entrance to 35-mile-long Russell Fiord creating a <span class="hlt">glacier</span>-dammed lake. After closure of the ice and moraine dam, runoff from mountain streams and glacial melt caused the level in ?Russell Lake? to rise until it eventually breached the dam on August 14, 2002. Daily mean inflows to the lake during the period of closure were estimated on the basis of lake stage data and the hypsometry of Russell Lake. Inflows were regressed against the daily mean streamflows of nearby Ophir Creek and Situk River to generate an equation for simulating Russell Lake inflow. The regression equation was used to produce 11 years of synthetic daily inflows to Russell Lake for the 1992-2002 water years. A flood-frequency analysis was applied to the peak daily mean inflows for these 11 years of record to generate a 100-year peak daily mean inflow of 235,000 cubic feet per second. Regional-regression equations also were applied to the Russell Lake <span class="hlt">basin</span>, yielding a 100-year inflow of 157,000 cubic feet per second.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17739514','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17739514"><span><span class="hlt">Glacier</span> Geophysics: Dynamic response of <span class="hlt">glaciers</span> to changing climate may shed light on processes in the earth's interior.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kamb, B</p> <p>1964-10-16</p> <p>From physical measurements on <span class="hlt">glaciers</span> and experimental studies of ice properties a framework of concept and theory is being built which bids fair to place <span class="hlt">glaciers</span> among the more quantitatively understandable phenomena in the earth sciences. Measurements of flow velocity, deformation and stress, ice thickness and channel configuration, temperature, internal structure of theice, mass and energy balance, and response to meteorological variables all contribute to this understanding, as do still other measurements hardly discussed here, such as electrical properties, radioactive age measurements, and detailed studies of chemical and isotopic composition. The obvious goals of this work-the interpretation of past and present <span class="hlt">glacier</span> fluctuations in terms of changes in world climate, and the prediction of <span class="hlt">glacier</span> behavior-remain elusive, even though a good conceptual groundwork has been laid for dealing with the more tractable aspects of these problems. Intriguing recent discoveries have been made about such matters as the way in which <span class="hlt">glaciers</span> react dynamically to changing conditions, the inter-relations between thermal regime and ice motion, the structural mechanisms of <span class="hlt">glacier</span> flow, and the changes produced in ice by flow. One can recognize in these developments the possibility that concepts derived from the study of <span class="hlt">glacier</span> flow may be applicable to phenomena of solid deformation deep in the earth. In this way <span class="hlt">glacier</span> geophysics may have a useful impact beyond the study of <span class="hlt">glaciers</span> themselves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.8585V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.8585V"><span>Future streamflow droughts in <span class="hlt">glacierized</span> catchments: the impact of dynamic <span class="hlt">glacier</span> modelling and changing thresholds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Van Tiel, Marit; Van Loon, Anne; Wanders, Niko; Vis, Marc; Teuling, Ryan; Stahl, Kerstin</p> <p>2017-04-01</p> <p>In <span class="hlt">glacierized</span> catchments, snowpack and <span class="hlt">glaciers</span> function as an important storage of water and hydrographs of highly <span class="hlt">glacierized</span> catchments in mid- and high latitudes thus show a clear seasonality with low flows in winter and high flows in summer. Due to the ongoing climate change we expect this type of storage capacity to decrease with resultant consequences for the discharge regime. In this study we focus on streamflow droughts, here defined as below average water availability specifically in the high flow season, and which methods are most suitable to characterize future streamflow droughts as regimes change. Two <span class="hlt">glacierized</span> catchments, Nigardsbreen (Norway) and Wolverine (Alaska), are used as case study and streamflow droughts are compared between two periods, 1975-2004 and 2071-2100. Streamflow is simulated with the HBV light model, calibrated on observed discharge and seasonal <span class="hlt">glacier</span> mass balances, for two climate change scenarios (RCP 4.5 & RCP 8.5). In studies on future streamflow drought often the same variable threshold of the past has been applied to the future, but in regions where a regime shift is expected this method gives severe "droughts" in the historic high-flow period. We applied the new alternative transient variable threshold, a threshold that adapts to the changing hydrological regime and is thus better able to cope with this issue, but has never been thoroughly tested in <span class="hlt">glacierized</span> catchments. As the <span class="hlt">glacier</span> area representation in the hydrological modelling can also influence the modelled discharge and the derived streamflow droughts, we evaluated in this study both the difference between the historical variable threshold (HVT) and transient variable threshold (TVT) and two different <span class="hlt">glacier</span> area conceptualisations (constant area (C) and dynamical area (D)), resulting in four scenarios: HVT-C, HVT-D, TVT-C and TVT-D. Results show a drastic decrease in the number of droughts in the HVT-C scenario due to increased <span class="hlt">glacier</span> melt. The deficit</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1918586S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1918586S"><span>Ocean impact on Nioghalvfjerdsfjorden <span class="hlt">Glacier</span>, Northeast Greenland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schaffer, Janin; Kanzow, Torsten; von Appen, Wilken-Jon; Mayer, Christoph</p> <p>2017-04-01</p> <p>The ocean plays an important role in modulating the mass balance of the Greenland Ice Sheet by delivering heat to the marine-terminating outlet <span class="hlt">glaciers</span> around Greenland. The largest of three outlet <span class="hlt">glaciers</span> draining the Northeast Greenland Ice Stream is Nioghalvfjerdsfjorden <span class="hlt">Glacier</span> (also referred to as 79 North <span class="hlt">Glacier</span>). Historic observations showed that warm waters of Atlantic origin are present in the subglacial cavity below the 80 km long floating ice tongue of the Nioghalvfjerdsfjorden <span class="hlt">Glacier</span> and cause strong basal melt at the grounding line, but to date it has been unknown how those warm water enter the cavity. In order to understand how Atlantic origin waters carry heat into the subglacial cavity beneath Nioghalvfjerdsfjorden <span class="hlt">Glacier</span>, we performed bathymetric, hydrographic, and velocity observations in the vicinity of the main <span class="hlt">glacier</span> calving front aboard RV Polarstern in summer 2016. The bathymetric multibeam data shows a 500 m deep and 2 km narrow passage downstream of a 310 m deep sill. This turned out to be the only location deep enough for an exchange of Atlantic waters between the <span class="hlt">glacier</span> cavity and the continental shelf. Hydrographic and velocity measurements revealed a density driven plume in the vicinity of the <span class="hlt">glacier</span> calving front causing a rapid flow of waters of Atlantic origin warmer 1°C into the subglacial cavity through the 500 m deep passage. In addition, glacially modified waters flow out of the <span class="hlt">glacier</span> cavity below the 80 m deep ice base. In the vicinity of the <span class="hlt">glacier</span>, the glacially modified waters form a distinct mixed layer situated above the Atlantic waters and below the ambient Polar water. At greater distances from the <span class="hlt">glacier</span> this layer is eroded by lateral mixing with ambient water. Based on our observations we will present an estimate of the ocean heat transport into the subglacial cavity. In comparison with historic observations we find an increase in Atlantic water temperatures throughout the last 20 years. The resulting</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.C21B0597A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.C21B0597A"><span>Bathymetry of Patagonia <span class="hlt">glacier</span> fjords and <span class="hlt">glacier</span> ice thickness from high-resolution airborne gravity combined with other data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>An, L.; Rignot, E.; Rivera, A.; Bunetta, M.</p> <p>2012-12-01</p> <p>The North and South Patagonia Ice fields are the largest ice masses outside Antarctica in the Southern Hemisphere. During the period 1995-2000, these <span class="hlt">glaciers</span> lost ice at a rate equivalent to a sea level rise of 0.105 ± 0.001 mm/yr. In more recent years, the <span class="hlt">glaciers</span> have been thinning more quickly than can be explained by warmer air temperatures and decreased precipitation. A possible cause is an increase in flow speed due to enhanced ablation of the submerged <span class="hlt">glacier</span> fronts. To understand the dynamics of these <span class="hlt">glaciers</span> and how they change with time, it is critical to have a detailed view of their ice thickness, the depth of the <span class="hlt">glacier</span> bed below sea or lake level, how far inland these <span class="hlt">glaciers</span> remain below sea or lake level, and whether bumps or hollows in the bed may slow down or accelerate their retreat. A grid of free-air gravity data over the Patagonia <span class="hlt">Glaciers</span> was collected in May 2012 and October 2012, funded by the Gordon and Betty Moore Foundation (GBMF) to measure ice thickness and sea floor bathymetry. This survey combines the Sander Geophysics Limited (SGL) AIRGrav system, SGL laser altimetry and Chilean CECS/UCI ANDREA-2 radar. To obtain high-resolution and high-precision gravity data, the helicopter operates at 50 knots (25.7 m/s) with a grid spacing of 400m and collects gravity data at sub mGal level (1 Gal =1 Galileo = 1 cm/s2) near <span class="hlt">glacier</span> fronts. We use data from the May 2012 survey to derive preliminarily high-resolution, high-precision thickness estimates and bathymetry maps of Jorge Montt <span class="hlt">Glacier</span> and San Rafael <span class="hlt">Glacier</span>. Boat bathymetry data is used to optimize the inversion of gravity over water and radar-derived thickness over <span class="hlt">glacier</span> ice. The bathymetry maps will provide a breakthrough in our knowledge of the ice fields and enable a new era of <span class="hlt">glacier</span> modeling and understanding that is not possible at present because ice thickness is not known.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Tectp.691..171L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Tectp.691..171L"><span>The Canada <span class="hlt">Basin</span> compared to the southwest South China Sea: Two marginal ocean <span class="hlt">basins</span> with hyper-extended continent-ocean transitions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Lu; Stephenson, Randell; Clift, Peter D.</p> <p>2016-11-01</p> <p>Both the Canada <span class="hlt">Basin</span> (a sub-<span class="hlt">basin</span> within the Amerasia <span class="hlt">Basin</span>) and southwest (SW) South China Sea preserve oceanic spreading centres and <span class="hlt">adjacent</span> passive continental margins characterized by broad COT zones with hyper-extended continental crust. We have investigated strain accommodation in the regions immediately <span class="hlt">adjacent</span> to the oceanic spreading centres in these two <span class="hlt">basins</span> using 2-D backstripping subsidence reconstructions, coupled with forward modelling constrained by estimates of upper crustal extensional faulting. Modelling is better constrained in the SW South China Sea but our results for the Canada <span class="hlt">Basin</span> are analogous. Depth-dependent extension is required to explain the great depth of both <span class="hlt">basins</span> because only modest upper crustal faulting is observed. A weak lower crust in the presence of high heat flow and, accordingly, a lower crust that extends far more the upper crust are suggested for both <span class="hlt">basins</span>. Extension in the COT may have continued even after seafloor spreading has ceased. The analogous results for the two <span class="hlt">basins</span> considered are discussed in terms of (1) constraining the timing and distribution of crustal thinning along the respective continental margins, (2) defining the processes leading to hyper-extension of continental crust in the respective tectonic settings and (3) illuminating the processes that control hyper-extension in these <span class="hlt">basins</span> and more generally.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70023558','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70023558"><span>Quaternary glacial, lacustrine, and fluvial interactions in the western Noatak <span class="hlt">basin</span>, Northwest Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hamilton, T.D.</p> <p>2001-01-01</p> <p>The 130 km long Noatak <span class="hlt">basin</span> is surrounded by mountains of the western Brooks Range. Middle and late Pleistocene <span class="hlt">glaciers</span> flowing southeast into the <span class="hlt">basin</span> dammed a succession of proglacial lakes defined by shorelines, outlet channels and upper limits of wave erosion. More than 60 bluffs along the Noatak River and its principal tributaries expose glacial and glaciolacustrine sediments that exhibit cut-and-fill relationships with interglacial and interstadial river-channel and floodplain deposits. This report focuses on the western Noatak <span class="hlt">basin</span>, where high bluffs created by deep postglacial erosion record four major glacial advances. During the Cutler advance, a floating ice tongue terminated in a large proglacial lake that filled the Noatak <span class="hlt">basin</span>. The retreating <span class="hlt">glacier</span> abandoned a trough along the valley center that subsequently filled with about 40m of sediment during several younger glaciations and probably two major interglacial episodes. Alluvium that formed near the beginning of the younger interglaciation contains the 140,000 yr old Old Crow tephra. The subsequent closely spaced Okak and Makpik advances are clearly younger than the maximum of the last interglaciation, but they preceded a middle Wisconsin (36-30 ka) nonglacial interval in the Noatak <span class="hlt">basin</span>. The Okak advance terminated in an extensive lake, whereas <span class="hlt">glaciers</span> of the Makpik and the subsequent Anisak advances flowed into much narrower lakes that filled only the <span class="hlt">basin</span> center. The Anisak advance, bracketed by radiocarbon ages of about 35 and 13.6 ka, represents the Last Glacial Maximum (LGM) in the western Noatak <span class="hlt">basin</span>. Correlations with the oldest and youngest glacial deposits of the central Brooks Range are clear, but relationships to events of intermediate age are more tenuous. Early Pleistocene and older glacial advances from the central Brooks Range must have filled the Noatak <span class="hlt">basin</span> and overflowed northward through Howard Pass. A younger glacial advance, of inferred middle Pleistoscene</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/971305','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/971305"><span>The influence of air temperature inversions on snowmelt and <span class="hlt">glacier</span> mass-balance simulations, Ammassalik island, SE Greenland</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Mernild, Sebastian Haugard; Liston, Glen</p> <p>2009-01-01</p> <p>In many applications, a realistic description of air temperature inversions is essential for accurate snow and <span class="hlt">glacier</span> ice melt, and <span class="hlt">glacier</span> mass-balance simulations. A physically based snow-evolution modeling system (SnowModel) was used to simulate eight years (1998/99 to 2005/06) of snow accumulation and snow and <span class="hlt">glacier</span> ice ablation from numerous small coastal marginal <span class="hlt">glaciers</span> on the SW-part of Ammassalik Island in SE Greenland. These <span class="hlt">glaciers</span> are regularly influenced by inversions and sea breezes associated with the <span class="hlt">adjacent</span> relatively low temperature and frequently ice-choked fjords and ocean. To account for the influence of these inversions on the spatiotemporal variation of airmore » temperature and snow and <span class="hlt">glacier</span> melt rates, temperature inversion routines were added to MircoMet, the meteorological distribution sub-model used in SnowModel. The inversions were observed and modeled to occur during 84% of the simulation period. Modeled inversions were defined not to occur during days with strong winds and high precipitation rates due to the potential of inversion break-up. Field observations showed inversions to extend from sea level to approximately 300 m a.s.l., and this inversion level was prescribed in the model simulations. Simulations with and without the inversion routines were compared. The inversion model produced air temperature distributions with warmer lower elevation areas and cooler higher elevation areas than without inversion routines due to the use of cold sea-breeze base temperature data from underneath the inversion. This yielded an up to 2 weeks earlier snowmelt in the lower areas and up to 1 to 3 weeks later snowmelt in the higher elevation areas of the simulation domain. Averaged mean annual modeled surface mass-balance for all <span class="hlt">glaciers</span> (mainly located above the inversion layer) was -720 {+-} 620 mm w.eq. y{sup -1} for inversion simulations, and -880 {+-} 620 mm w.eq. y{sup -1} without the inversion routines, a difference of 160 mm w</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1810891N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1810891N"><span>Internationally coordinated <span class="hlt">glacier</span> monitoring - a timeline since 1894</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nussbaumer, Samuel U.; Armstrong, Richard; Fetterer, Florence; Gärtner-Roer, Isabelle; Hoelzle, Martin; Machguth, Horst; Mölg, Nico; Paul, Frank; Raup, Bruce H.; Zemp, Michael</p> <p>2016-04-01</p> <p>Changes in <span class="hlt">glaciers</span> and ice caps provide some of the clearest evidence of climate change, with impacts on sea-level variations, regional hydrological cycles, and natural hazard situations. Therefore, <span class="hlt">glaciers</span> have been recognized as an Essential Climate Variable (ECV). Internationally coordinated collection and distribution of standardized information about the state and change of <span class="hlt">glaciers</span> and ice caps was initiated in 1894 and is today organized within the Global Terrestrial Network for <span class="hlt">Glaciers</span> (GTN-G). GTN-G ensures the continuous development and adaptation of the international strategies to the long-term needs of users in science and policy. A GTN-G Steering Committee coordinates, supports and advices the operational bodies responsible for the international <span class="hlt">glacier</span> monitoring, which are the World <span class="hlt">Glacier</span> Monitoring Service (WGMS), the US National Snow and Ice Data Center (NSIDC), and the Global Land Ice Measurements from Space (GLIMS) initiative. In this presentation, we trace the development of the internationally coordinated <span class="hlt">glacier</span> monitoring since its beginning in the 19th century. Today, several online databases containing a wealth of diverse data types with different levels of detail and global coverage provide fast access to continuously updated information on <span class="hlt">glacier</span> fluctuation and inventory data. All <span class="hlt">glacier</span> datasets are made freely available through the respective operational bodies within GTN-G, and can be accessed through the GTN-G Global <span class="hlt">Glacier</span> Browser (http://www.gtn-g.org/data_browser.html). <span class="hlt">Glacier</span> inventory data (e.g., digital outlines) are available for about 180,000 <span class="hlt">glaciers</span> (GLIMS database, RGI - Randolph <span class="hlt">Glacier</span> Inventory, WGI - World <span class="hlt">Glacier</span> Inventory). <span class="hlt">Glacier</span> front variations with about 45,000 entries since the 17th century and about 6,200 glaciological and geodetic mass (volume) change observations dating back to the 19th century are available in the Fluctuations of <span class="hlt">Glaciers</span> (FoG) database. These datasets reveal clear evidence that</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMGC21A0852S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMGC21A0852S"><span><span class="hlt">Glacier</span> Sensitivity Across the Andes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sagredo, E. A.; Lowell, T. V.; Rupper, S.</p> <p>2010-12-01</p> <p>Most of the research on causes driving former glacial fluctuations, and the climatic signals involved, has focused on the comparisons of sequences of glacial events in separate regions of the world and their temporal-phasing relationship with terrestrial or extraterrestrial climate-forcing mechanisms. Nevertheless the climatic signals related with these glacial advances are still under debate. This impossibility to resolve these questions satisfactorily have been generally attributed to the insufficiently precise chronologies and unevenly distributed records. However, behind these ideas lies the implicit assumption that <span class="hlt">glaciers</span> situated in different climate regimes respond uniformly to similar climatic perturbations. This ongoing research is aimed to explore the climate-<span class="hlt">glacier</span> relationship at regional scale, through the analysis of the spatial variability of <span class="hlt">glacier</span> sensitivity to climatic change. By applying a Surface Energy Mass Balance model (SEMB) developed by Rupper and Roe (2008) to <span class="hlt">glaciers</span> located in different climatic regimes, we analyzed the spatial variability of mass balance changes under different baseline conditions and under different scenarios of climatic change. For the sake of this research, the analysis is being focused on the Andes, which in its 9,000 km along the western margin of South America offers an unparalleled climatic diversity. Preliminary results suggest that above some threshold of climate change (a hypothetical uniform perturbation), all the <span class="hlt">glaciers</span> across the Andes would respond in the “same direction” (advancing or retreating). Below that threshold, <span class="hlt">glaciers</span> located in some climatic regimes may be insensitive to the specific perturbation. On the other hand, <span class="hlt">glaciers</span> located in different climatic regimes may exhibit a “different magnitude” of change under a uniform climatic perturbation. Thus, <span class="hlt">glaciers</span> located in the dry Andes of Perú, Chile and Argentina are more sensitive to precipitation changes than variations in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.4807P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.4807P"><span><span class="hlt">Glacier</span>-specific elevation changes in western Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Paul, Frank; Le Bris, Raymond</p> <p>2013-04-01</p> <p>Deriving <span class="hlt">glacier</span>-specific elevation changes from DEM differencing and digital <span class="hlt">glacier</span> outlines is rather straight-forward if the required datasets are available. Calculating such changes over large regions and including <span class="hlt">glaciers</span> selected for mass balance measurements in the field, provides a possibility to determine the representativeness of the changes observed at these <span class="hlt">glaciers</span> for the entire region. The related comparison of DEM-derived values for these <span class="hlt">glaciers</span> with the overall mean avoids the rather error-prone conversion of volume to mass changes (e.g. due to unknown densities) and gives unit-less correction factors for upscaling the field measurements to a larger region. However, several issues have to be carefully considered, such as proper co-registration of the two DEMs, date and accuracy of the datasets compared, as well as source data used for DEM creation and potential artefacts (e.g. voids). In this contribution we present an assessment of the representativeness of the two mass balance <span class="hlt">glaciers</span> Gulkana and Wolverine for the overall changes of nearly 3200 <span class="hlt">glaciers</span> in western Alaska over a ca. 50-year time period. We use an elevation change dataset from a study by Berthier et al. (2010) that was derived from the USGS DEM of the 1960s (NED) and a more recent DEM derived from SPOT5 data for the SPIRIT project. Additionally, the ASTER GDEM was used as a more recent DEM. Historic <span class="hlt">glacier</span> outlines were taken from the USGS digital line graph (DLG) dataset, corrected with the digital raster graph (DRG) maps from USGS. Mean <span class="hlt">glacier</span> specific elevation changes were derived based on drainage divides from a recently created inventory. Land-terminating, lake-calving and tidewater <span class="hlt">glaciers</span> were marked in the attribute table to determine their changes separately. We also investigated the impact of handling potential DEM artifacts in three different ways and compared elevation changes with altitude. The mean elevation changes of Gulkana and Wolverine <span class="hlt">glaciers</span> (about -0</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1615948K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1615948K"><span>Towards improved cirque <span class="hlt">glacier</span> reconstructions: differentiating glacial- from <span class="hlt">non</span>-glacial sediments by means of environmental magnetism.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kvisvik, Bjørn Christian; Paasche, Øyvind; Olaf Dahl, Svein</p> <p>2014-05-01</p> <p>Skriufonnen, a small cirque <span class="hlt">glacier</span> (0.4 km2) in Southern Norway, has been monitored for the last 10 years, revealing a short response time to on-going climate change. This is the only remaining <span class="hlt">glacier</span> in the central mountain massif known as Rondane where investigations of past climate variability are scarce. A series of short (HTH, n=8) and long (piston, n=6) cores from two lakes located downstream of Skriufonnen were retrieved and sediments were dated and analysed. In order to complement and validate lake sediment interpretations i.e., the potential connection to <span class="hlt">glacier</span> variability, a number of soil samples was collected from the surrounding catchment. The six 110 mm piston cores (< 3.1 m length) and eight sediment surface cores were analysed for grain size distribution, geochemical elements (ITRAX XRF-scanning), organic matter content (LOI), magnetic parameters (magnetic susceptibility; surface and bulk), anhysteretic remanent magnetization (ARM) and Saturation Isothermal remanent magnetizations (sIRM). Consistent age-depth relationships were obtained by AMS-C14 and Pb210 dates showing that the cores cover at least the last 10 000 years. High-resolution analysis (XRF and MS) reveals centennial trends, but also distinct changes in frequency and amplitude. A quiescent period during the Holocene Thermal Optimum (9-6 ka) is followed by a sudden onset of Neoglacial (3.8 ka) activity peaking at 2.4 ka. The Little Ice Age (LIA) peaked at 1800 AD. A weak magnetic signal is observed in all cores. This is explained by the fact that Rondane is made of Sparagmite, an arkosic sandstone partly consisting of metamorphosed sandstone and conglomerate with high content of quarts (SiO2) (between 80 to 87 %) and Feldspar. The Sparagmite is resistant to chemical weathering, making the soils dry and sandy. Catchment sediment samples, running in a transect all the way up from the lakes to the <span class="hlt">glacier</span> snout were sieved into various size classes (250, 125, 63, 38, 20 μm) prior to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA21509.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA21509.html"><span>New Zealand <span class="hlt">Glaciers</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-03-09</p> <p>New Zealand contains over 3,000 <span class="hlt">glaciers</span>, most of which are in the Southern Alps on the South Island. Since 1890, the <span class="hlt">glaciers</span> have been retreating, with short periods of small advances, as shown in this image from NASA Terra spacecraft. The image cover an area of 39 by 46 km, and are located at 43.7 degrees south, 170 degrees east. http://photojournal.jpl.nasa.gov/catalog/PIA21509</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70029429','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70029429"><span>Pliocene transpressional modification of depositional <span class="hlt">basins</span> by convergent thrusting <span class="hlt">adjacent</span> to the "Big Bend" of the San Andreas fault: An example from Lockwood Valley, southern California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kellogg, K.S.; Minor, S.A.</p> <p>2005-01-01</p> <p>The "Big Bend" of the San Andreas fault in the western Transverse Ranges of southern California is a left stepping flexure in the dextral fault system and has long been recognized as a zone of relatively high transpression compared to <span class="hlt">adjacent</span> regions. The Lockwood Valley region, just south of the Big Bend, underwent a profound change in early Pliocene time (???5 Ma) from <span class="hlt">basin</span> deposition to contraction, accompanied by widespread folding and thrusting. This change followed the recently determined initiation of opening of the northern Gulf of California and movement along the southern San Andreas fault at about 6.1 Ma, with the concomitant formation of the Big Bend. Lockwood Valley occupies a 6-km-wide, fault-bounded structural <span class="hlt">basin</span> in which converging blocks of Paleoproterozoic and Cretaceous crystalline basement and upper Oligocene and lower Miocene sedimentary rocks (Plush Ranch Formation) were thrust over Miocene and Pliocene <span class="hlt">basin</span>-fill sedimentary rocks (in ascending order, Caliente Formation, Lockwood Clay, and Quatal Formation). All the pre-Quatal sedimentary rocks and most of the Pliocene Quatal Formation were deposited during a mid-Tertiary period of regional transtension in a crustal block that underwent little clockwise vertical-axis rotation as compared to crustal blocks to the south. Ensuing Pliocene and Quaternary transpression in the Big Bend region began during deposition of the poorly dated Quatal Formation and was marked by four converging thrust systems, which decreased the areal extent of the sedimentary <span class="hlt">basin</span> and formed the present Lockwood Valley structural <span class="hlt">basin</span>. None of the thrusts appears presently active. Estimated shortening across the center of the <span class="hlt">basin</span> was about 30 percent. The fortnerly defined eastern Big Pine fault, now interpreted to be two separate, oppositely directed, contractional reverse or thrust faults, marks the northwestern structural boundary of Lockwood Valley. The complex geometry of the Lockwood Valley <span class="hlt">basin</span> is similar</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUSM.U22A..06K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUSM.U22A..06K"><span><span class="hlt">Glaciers</span> in 21st Century Himalayan Geopolitics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kargel, J. S.; Wessels, R.; Kieffer, H. H.</p> <p>2002-05-01</p> <p><span class="hlt">Glaciers</span> are ablating rapidly the world over. Nowhere are the rates of retreat and downwasting greater than in the Hindu Kush-Himalaya (HKH) region. It is estimated that over the next century, 40,000 square kilometers of present <span class="hlt">glacier</span> area in the HKH region will become ice free. Most of this area is in major valleys and the lowest glaciated mountain passes. The existence and characteristics of <span class="hlt">glaciers</span> have security impacts, and rapidly changing HKH <span class="hlt">glaciers</span> have broad strategic implications: (1) <span class="hlt">Glaciers</span> supply much of the fresh water and hydroelectric power in South and Central Asia, and so <span class="hlt">glaciers</span> are valuable resources. (2) Shared economic interests in water, hydroelectricity, flood hazards, and habitat preservation are a force for common cause and reasoned international relations. (3) <span class="hlt">Glaciers</span> and their high mountains generally pose a natural barrier tending to isolate people. Historically, they have hindered trade and intercultural exchanges and have protected against aggression. This has further promoted an independent spirit of the region's many ethnic groups. (4) Although <span class="hlt">glaciers</span> are generally incompatible with human development and habitation, many of the HKH region's <span class="hlt">glaciers</span> and their mountains have become sanctuaries and transit routes for militants. Siachen <span class="hlt">Glacier</span> in Kashmir has for 17 years been "the world's highest battlefield," with tens of thousands of troops deployed on both sides of the India/Pakistan line of control. In 1999, that conflict threatened to trigger all-out warfare, and perhaps nuclear warfare. Other recent terrorist and military action has taken place on <span class="hlt">glaciers</span> in Kyrgyzstan and Tajikistan. As terrorists are forced from easily controlled territories, many may tend to migrate toward the highest ground, where definitive encounters may take place in severe alpine glacial environments. This should be a major concern in Nepali security planning, where an Army offensive is attempting to reign in an increasingly robust and brutal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1915896D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1915896D"><span>A fjord-<span class="hlt">glacier</span> coupled system model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Andrés, Eva; Otero, Jaime; Navarro, Francisco; Prominska, Agnieszka; Lapazaran, Javier; Walczowski, Waldemar</p> <p>2017-04-01</p> <p>With the aim of studying the processes occurring at the front of marine-terminating <span class="hlt">glaciers</span>, we couple a fjord circulation model with a flowline <span class="hlt">glacier</span> dynamics model, with subglacial discharge and calving, which allows the calculation of submarine melt and its influence on calving processes. For ocean modelling, we use a general circulation model, MITgcm, to simulate water circulation driven by both fjord conditions and subglacial discharge, and for calculating submarine melt rates at the <span class="hlt">glacier</span> front. To constrain freshwater input to the fjord, we use estimations from European Arctic Reanalysis (EAR). To determine the optimal values for each run period, we perform a sensitivity analysis of the model to subglacial discharge variability, aimed to get the best fit of model results to observed temperature and salinity profiles in the fjord for each of these periods. Then, we establish initial and boundary fjord conditions, which we vary weekly-fortnightly, and calculate the submarine melt rate as a function of depth at the calving front. These data are entered into the <span class="hlt">glacier</span>-flow model, Elmer/Ice, which has been added a crevasse-depth calving model, to estimate the <span class="hlt">glacier</span> terminus position at a weekly time resolution. We focus our study on the Hansbreen <span class="hlt">Glacier</span>-Hansbukta Fjord system, in Southern Spitsbergen, Svalbard, where a large set of data are available for both <span class="hlt">glacier</span> and fjord. The bathymetry of the entire system has been determined from ground penetrating radar and sonar data. In the fjord we have got temperature and salinity data from CTDs (May to September, 2010-2014) and from a mooring (September to May, 2011-2012). For Hansbreen, we use <span class="hlt">glacier</span> surface topography data from the SPIRIT DEM, surface mass balance from EAR, centre line <span class="hlt">glacier</span> velocities from stake measurements (May 2005-April 2011), weekly terminus positions from time-lapse photos (Sept. 2009-Sept. 2011), and sea-ice concentrations from time-lapse photos and Nimbus-7 SMMR and DMSP SSM</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.C22A..02N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.C22A..02N"><span>Response of major Greenland outlet <span class="hlt">glaciers</span> to oceanic and atmospheric forcing: Results from numerical modeling on Petermann, Jakobshavn and Helheim <span class="hlt">Glacier</span>.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nick, F. M.; Vieli, A.; Pattyn, F.; Van de Wal, R.</p> <p>2011-12-01</p> <p>Oceanic forcing has been suggested as a major trigger for dynamic changes of Greenland outlet <span class="hlt">glaciers</span>. Significant melting near their calving front or beneath the floating tongue and reduced support from sea ice or ice melange in front of their calving front can result in retreat of the terminus or the grounding line, and an increase in calving activities. Depending on the geometry and basal topography of the <span class="hlt">glacier</span>, these oceanic forcing can affect the <span class="hlt">glacier</span> dynamic differently. Here, we carry out a comparison study between three major outlet <span class="hlt">glaciers</span> in Greenland and investigate the impact of a warmer ocean on <span class="hlt">glacier</span> dynamics and ice discharge. We present results from a numerical ice-flow model applied to Petermann <span class="hlt">Glacier</span> in the north, Jakobshavn <span class="hlt">Glacier</span> in the west, and Helheim <span class="hlt">Glacier</span> in the southeast of Greenland.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A51J..08F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A51J..08F"><span>High pollution events in the Great Salt Lake <span class="hlt">Basin</span> and its <span class="hlt">adjacent</span> valleys. Insights on mechanisms and spatial distribution of the formation of secondary aerosol.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Franchin, A.; Middlebrook, A. M.; Baasandorj, M.; Brown, S. S.; Fibiger, D. L.; Goldberger, L.; McDuffie, E. E.; Moravek, A.; Murphy, J. G.; Thornton, J. A.; Womack, C.</p> <p>2017-12-01</p> <p>High pollution events are common in many locations in the U.S.A. and around the world. They can last several days or up to weeks and they negatively affect human health, deteriorate visibility, and increase premature mortality. The main causes for high pollution events are related to meteorology and sources. They often happen in the winter, when high emissions, stagnation and reduced mixing, due to a shallow boundary layer, cause high concentrations of pollutants to accumulate. In the last decades, the air quality in the U.S. has seen an overall improvement, due to the reductions in particulate and gaseous pollutants. However, some areas remain critical. The Great Salt Lake <span class="hlt">Basin</span> and its <span class="hlt">adjacent</span> valleys are currently areas where high pollution events are a serious environmental problem involving more than 2.4 million people. We will present the results of the Utah Wintertime Fine Particulate Study (UWFPS) that took place in winter 2017. During UWFPS, we carried out airborne measurements of aerosol chemical composition and precursor vapor concentrations over the Great Salt Lake <span class="hlt">Basin</span> and its <span class="hlt">adjacent</span> valleys. We will give insights into how and under which conditions conversion of precursor vapors into aerosol particles takes place in the area. We will also present a comparison of our measurements with models that will provide an insight of the mechanisms that lead to the formation of secondary aerosol particles. With the results of our work, we aim to inform strategies for pollution control in the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001482.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001482.html"><span><span class="hlt">Glaciers</span> and Sea Level Rise</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-08</p> <p>The Aletsch <span class="hlt">Glacier</span> in Switzerland is the largest valley <span class="hlt">glacier</span> in the Alps. Its volume loss since the middle of the 19th century is well-visible from the trimlines to the right of the image. To learn about the contributions of <span class="hlt">glaciers</span> to sea level rise, visit: www.nasa.gov/topics/earth/features/<span class="hlt">glacier</span>-sea-rise.html Credit: Frank Paul, University of Zurich NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1811394M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1811394M"><span>Evolution of hut access facing <span class="hlt">glacier</span> shrinkage in the Mer de Glace <span class="hlt">basin</span> (Mont Blanc massif, France)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mourey, Jacques; Ravanel, Ludovic</p> <p>2016-04-01</p> <p>Given the evolution of high mountain environment due to global warming, mountaineering routes and huts accesses are more and more strongly affected by glacial shrinkage and concomitant gravity processes, but almost no studies have been conducted on this relationship. The aim of this research is to describe and explain the evolution over the last century of the access to the five alpine huts around the Mer de Glace <span class="hlt">glacier</span> (Mont Blanc massif), the larger French <span class="hlt">glacier</span> (length = 11.5 km, area = 30 km²), a major place for Alpine tourism since 1741 and the birthplace of mountaineering, by using several methods (comparing photographs, surveying, collecting historical documents). While most of the 20th century shows no marked changes, loss of ice thickness and associated erosion of lateral moraines generate numerous and significant changes since the 1990s. Boulder falls, rockfalls and landslides are the main geomorphological processes that affect the access, while the <span class="hlt">glacier</span> surface lowering makes access much longer and more unstable. The danger is then greatly increased and the access must be relocated and/or equipped more and more frequently (e.g. a total of 520 m of ladders has been added). This questions the future accessibility to the huts, jeopardizing an important part of mountaineering and its linked economy in the Mer de Glace area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1919373E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1919373E"><span>Tracer-based identification of rock <span class="hlt">glacier</span> thawing in a <span class="hlt">glacierized</span> Alpine catchment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Engel, Michael; Penna, Daniele; Tirler, Werner; Comiti, Francesco</p> <p>2017-04-01</p> <p>Current warming in high mountains leads to increased melting of snow, <span class="hlt">glacier</span> ice and permafrost. In particular rock <span class="hlt">glaciers</span>, as a creeping form of mountain permafrost, may release contaminants such as heavy metals into the stream during intense melting periods in summer. This may have strong impacts on both water quantity and quality of fresh water resources but might also harm the aquatic fauna in mountain regions. In this context, the present study used stable isotopes of water and electrical conductivity (EC) combined with trace, major and minor elements to identify the influence of permafrost thawing on the water quality in the <span class="hlt">glacierized</span> Solda catchment (130 km2) in South Tyrol (Italy). We carried out a monthly sampling of two springs fed by an active rock <span class="hlt">glacier</span> at about 2600 m a.s.l. from July to October 2015. Furthermore, we took monthly water samples from different stream sections of the Solda River (1110 to m a.s.l.) from March to November 2015. Meteorological data were measured by an Automatic Weather Station at 2825 m a.s.l. of the Hydrographic Office (Autonomous Province of Bozen-Bolzano). First results show that water from the rock <span class="hlt">glacier</span> springs and stream water fell along the global meteoric water line. Spring water was slightly more variable in isotopic ratio (δ2H: -91 to - 105 ) and less variable in dissolved solutes (EC: 380 to 611 μS/cm) than stream water (δ2H: -96 to - 107 ‰ and EC: 212 to 927 μS/cm). Both spring water and stream water showed a pronounced drop in EC during July and August, very likely induced by increased melt water dilution. In both water types, element concentrations of Ca and Mg were highest (up to 160 and 20 mg/l, respectively). In September, spring water showed higher concentrations in Cu, As, and Pb than stream water, indicating that these elements partly exceeded the concentration limit for drinking water. These observations highlight the important control, which rock <span class="hlt">glacier</span> thawing may have on water quality</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CG.....94...68S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CG.....94...68S"><span>A GRASS GIS module to obtain an estimation of <span class="hlt">glacier</span> behavior under climate change: A pilot study on Italian <span class="hlt">glacier</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Strigaro, Daniele; Moretti, Massimiliano; Mattavelli, Matteo; Frigerio, Ivan; Amicis, Mattia De; Maggi, Valter</p> <p>2016-09-01</p> <p>The aim of this work is to integrate the Minimal <span class="hlt">Glacier</span> Model in a Geographic Information System Python module in order to obtain spatial simulations of <span class="hlt">glacier</span> retreat and to assess the future scenarios with a spatial representation. The Minimal <span class="hlt">Glacier</span> Models are a simple yet effective way of estimating <span class="hlt">glacier</span> response to climate fluctuations. This module can be useful for the scientific and glaciological community in order to evaluate <span class="hlt">glacier</span> behavior, driven by climate forcing. The module, called r.glacio.model, is developed in a GRASS GIS (GRASS Development Team, 2016) environment using Python programming language combined with different libraries as GDAL, OGR, CSV, math, etc. The module is applied and validated on the Rutor <span class="hlt">glacier</span>, a <span class="hlt">glacier</span> in the south-western region of the Italian Alps. This <span class="hlt">glacier</span> is very large in size and features rather regular and lively dynamics. The simulation is calibrated by reconstructing the 3-dimensional dynamics flow line and analyzing the difference between the simulated flow line length variations and the observed <span class="hlt">glacier</span> fronts coming from ortophotos and DEMs. These simulations are driven by the past mass balance record. Afterwards, the future assessment is estimated by using climatic drivers provided by a set of General Circulation Models participating in the Climate Model Inter-comparison Project 5 effort. The approach devised in r.glacio.model can be applied to most alpine <span class="hlt">glaciers</span> to obtain a first-order spatial representation of <span class="hlt">glacier</span> behavior under climate change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.C53D0765V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.C53D0765V"><span>A Simple Water Balance Model Adapted for Arctic Hydrology Reveals <span class="hlt">Glacier</span> and Streamflow Responses to Climate Change in the Copper River, Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Valentin, M. M.; Hay, L.; Van Beusekom, A. E.; Viger, R. J.; Hogue, T. S.</p> <p>2016-12-01</p> <p>Forecasting the hydrologic response to climate change in Alaska's glaciated watersheds remains daunting for hydrologists due to sparse field data and few modeling tools, which frustrates efforts to manage and protect critical aquatic habitat. Approximately 20% of the 64,000 square kilometer Copper River watershed is glaciated, and its <span class="hlt">glacier</span>-fed tributaries support renowned salmon fisheries that are economically, culturally, and nutritionally invaluable to the local communities. This study adapts a simple, yet powerful, conceptual hydrologic model to simulate changes in the timing and volume of streamflow in the Copper River, Alaska as <span class="hlt">glaciers</span> change under plausible future climate scenarios. The USGS monthly water balance model (MWBM), a hydrologic tool used for two decades to evaluate a broad range of hydrologic questions in the contiguous U.S., was enhanced to include <span class="hlt">glacier</span> melt simulations and remotely sensed data. In this presentation we summarize the technical details behind our MWBM adaptation and demonstrate its use in the Copper River <span class="hlt">Basin</span> to evaluate <span class="hlt">glacier</span> and streamflow responses to climate change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1710743B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1710743B"><span>Geomorphology and Ice Content of <span class="hlt">Glacier</span> - Rock <span class="hlt">Glacier</span> &ndash; Moraine Complexes in Ak-Shiirak Range (Inner Tien Shan, Kyrgyzstan)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bolch, Tobias; Kutuzov, Stanislav; Rohrbach, Nico; Fischer, Andrea; Osmonov, Azamat</p> <p>2015-04-01</p> <p>Meltwater originating from the Tien Shan is of high importance for the runoff to the arid and semi-arid region of Central Asia. Previous studies estimate a <span class="hlt">glaciers</span>' contribution of about 40% for the Aksu-Tarim Catchment, a transboundary watershed between Kyrgyzstan and China. Large parts of the Ak-Shiirak Range drain into this watershed. <span class="hlt">Glaciers</span> in Central and Inner Tien Shan are typically polythermal or even cold and surrounded by permafrost. Several <span class="hlt">glaciers</span> terminate into large moraine complexes which show geomorphological indicators of ice content such as thermo-karst like depressions, and further downvalley signs of creep such as ridges and furrows and a fresh, steep rock front which are typical indicators for permafrost creep ("rock <span class="hlt">glacier</span>"). Hence, <span class="hlt">glaciers</span> and permafrost co-exist in this region and their interactions are important to consider, e.g. for the understanding of glacial and periglacial processes. It can also be assumed that the ice stored in these relatively large dead-ice/moraine-complexes is a significant amount of the total ice storage. However, no detailed investigations exist so far. In an initial study, we investigated the structure and ice content of two typical <span class="hlt">glacier</span>-moraine complexes in the Ak-Shiirak-Range using different ground penetrating radar (GPR) devices. In addition, the geomorphology was mapped using high resolution satellite imagery. The structure of the moraine-rock <span class="hlt">glacier</span> complex is in general heterogeneous. Several dead ice bodies with different thicknesses and moraine-derived rock <span class="hlt">glaciers</span> with different stages of activities could be identified. Few parts of these "rock <span class="hlt">glaciers</span>" contain also massive ice but the largest parts are likely characterised by rock-ice layers of different thickness and ice contents. In one <span class="hlt">glacier</span> forefield, the thickness of the rock-ice mixture is partly more than 300 m. This is only slightly lower than the maximum thickness of the <span class="hlt">glacier</span> ice. Our measurements revealed that up to 20% of</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Geomo.311....1A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Geomo.311....1A"><span>Debris thickness patterns on debris-covered <span class="hlt">glaciers</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Anderson, Leif S.; Anderson, Robert S.</p> <p>2018-06-01</p> <p>Many debris-covered <span class="hlt">glaciers</span> have broadly similar debris thickness patterns: surface debris thickens and tends to transition from convex- to concave-up-down <span class="hlt">glacier</span>. We explain this pattern using theory (analytical and numerical models) paired with empirical observations. Down <span class="hlt">glacier</span> debris thickening results from the conveyor-belt-like nature of the <span class="hlt">glacier</span> surface in the ablation zone (debris can typically only be added but not removed) and from the inevitable decline in ice surface velocity toward the terminus. Down-<span class="hlt">glacier</span> thickening of debris leads to the reduction of sub-debris melt and debris emergence toward the terminus. Convex-up debris thickness patterns occur near the up-<span class="hlt">glacier</span> end of debris covers where debris emergence dominates (ablation controlled). Concave-up debris thickness patterns occur toward <span class="hlt">glacier</span> termini where declining surface velocities dominate (velocity controlled). A convex-concave debris thickness profile inevitably results from the transition between ablation-control and velocity-control down-<span class="hlt">glacier</span>. Debris thickness patterns deviating from this longitudinal shape are most likely caused by changes in hillslope debris supply through time. By establishing this expected debris thickness pattern, the effects of climate change on debris cover can be better identified.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960000908','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960000908"><span>SAR investigations of <span class="hlt">glaciers</span> in northwestern North America</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lingle, Craig S.; Harrison, William D.</p> <p>1995-01-01</p> <p>The objective of this project was to investigate the utility of satellite synthetic aperture radar (SAR) imagery for measurement of geophysical parameters on Alaskan <span class="hlt">glaciers</span> relevant to their mass balance and dynamics, including: (1) the positions of firn lines (late-summer snow lines); (2) surface velocities on fast-flowing (surging) <span class="hlt">glaciers</span>, and also on slower steady-flow <span class="hlt">glaciers</span>; and (3) the positions and changes in the positions of <span class="hlt">glacier</span> termini. Preliminary studies of topography and <span class="hlt">glacier</span> surface velocity with SAR interferometry have also been carried out. This project was motivated by the relationships of multi-year to decadal changes in <span class="hlt">glacier</span> geometry to changing climate, and the probable significant contribution of Alaskan <span class="hlt">glaciers</span> to rising sea level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUSM.C21B..04B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUSM.C21B..04B"><span>Ongoing calving-frontal dynamics of <span class="hlt">glaciers</span> in the Northern Patagonia Icefield, Chile</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bown, F.; Rivera, A.; Burger, F.; Carrión, D.; Cisternas, S.; Gacitúa, G.; Pena, M.; Oberreuter, J.; Silva, R.; Uribe, J. A.; Wendt, A.; Zamora, R.</p> <p>2013-05-01</p> <p>Patagonian <span class="hlt">glaciers</span> are increasingly contributing to the global-sea level rise due to negative mass balances in recent decades, in spite of moderated temperature and precipitation changes taking place in the region. The Austral Chilean <span class="hlt">glaciers</span> retreat and thinning are strongly influenced by local topography and frontal characteristics, both playing a key role in disrupting <span class="hlt">glacier</span> responses. One of the main ice bodies in this region is the Northern Patagonian Icefield ( NPI, 46S/73W, 3953 km2), a plateau from where tens of outlet <span class="hlt">glaciers</span> have been inventoried. Many of these <span class="hlt">glaciers</span> are ending at sea or freshwater lakes where they are calving. This calving feature is typically associated to <span class="hlt">non</span>-climatic fluctuations characterized by abnormally-high and sudden retreat and other exacerbated behaviors such as ice flow acceleration and dynamical thinning. The main aim of this work is the study of recent calving dynamics of three <span class="hlt">glaciers</span> of the NPI, in order to analyze similarities versus differences associated to their location, topographical constraints and bathymetry, among other features. With this aim, airborne LIDAR and radar surveys, as well as field trips were conducted to the area in year 2012 where several instruments and sensors were installed. The selected study sites were the NPI eastern side freshwater calving <span class="hlt">glaciers</span> Colonia (47.19S/73.29W) and Nef (47.03S/73.27W), and the NPI western margin tidewater calving San Rafael <span class="hlt">glacier</span> (46.70S/73.76W). With all the collected data, calving fluxes of 0.03 km3 a-1 and 0.08 km3 a-1 were detected at Glaciares Colonia and Nef respectively. At San Rafael, the calving flux was much higher (0.94 km3 a-1) mainly due to a deeper bathymetry near the <span class="hlt">glacier</span> front, and very high velocities (10m d-1) compared to the eastern side <span class="hlt">glaciers</span>. At Glaciar San Rafael the calving flux is very likely modulated by tidal components and local buoyancy conditions, while at the eastern <span class="hlt">glaciers</span>, calving is a near marginal feature</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMOS33E..07M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMOS33E..07M"><span>Morphologic Variability of two <span class="hlt">Adjacent</span> Mass-Transport Deposits: Twin Slides, Gela <span class="hlt">Basin</span> (Sicily Channel).</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Minisini, D.; Trincardi, F.; Asioli, A.; Canu, M.; Foglini, F.</p> <p>2006-12-01</p> <p>Integrating geophysical, sedimentological, structural and paleontological data, we reconstruct the age, size and internal geometry of two <span class="hlt">adjacent</span> and recent mass-transport deposits (Twin Slides) exposed on the seafloor of Gela <span class="hlt">Basin</span> (Sicily Channel). Twin Slides are coeval (late-Holocene), and were likely triggered by an earthquake. Twin Slides originated from the mobilization of Pleistocene slope units, are only 6 km apart from each other, have their headscarps in similar water depth (230 m), and have a comparable run out distance (ca. 10 km). Both slides suggest a multistage evolution, but differ in internal organization and morphological expression. The northern slide shows a deposit characterised by pressure ridges in the toe region suggesting a component of plastic deformation, while the southern slide is characterised by large blocks and a reduced thickness of displaced masses. We ascribe the difference in deformation style and resulting morphology to the stratigraphic architecture of the Pleistocene progradational units involved in failure. In the case of the blocky southern slide the units affected by failure are slightly older (Eemian or pre-Emian) and more consolidated; furthermore, in the area where the headscarp is located these units appear affected by shallow faulting likely resulting in the definition of large blocks. The northern slide, instead, affects progradational units of the Last Glacial Maximum in an area where these units are more than 100 m thick and, possibly, underconsolidated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT........60D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT........60D"><span>Evaluating <span class="hlt">glacier</span> movement fluctuations using remote sensing: A case study of the Baird, Patterson, LeConte, and Shakes <span class="hlt">glaciers</span> in central Southeastern Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Davidson, Robert Howard</p> <p></p> <p>Global Land Survey (GLS) data encompassing Landsat Multispectral Scanner (MSS), Landsat 5's Thematic Mapper (TM), and Landsat 7's Enhanced Thematic Mapper Plus (ETM+) were used to determine the terminus locations of Baird, Patterson, LeConte, and Shakes <span class="hlt">Glaciers</span> in Alaska in the time period 1975-2010. The sequences of the terminuses locations were investigated to determine the movement rates of these <span class="hlt">glaciers</span> with respect to specific physical and environmental conditions. GLS data from 1975, 1990, 2000, 2005, and 2010 in false-color composite images enhancing ice-snow differentiation and Iterative Self-Organizing (ISO) Data Cluster Unsupervised Classifications were used to 1) quantify the movement rates of Baird, Patterson, LeConte, and Shakes <span class="hlt">Glaciers</span>; 2) analyze the movement rates for <span class="hlt">glaciers</span> with similar terminal terrain conditions and; 3) analyze the movement rates for <span class="hlt">glaciers</span> with dissimilar terminal terrain conditions. From the established sequence of terminus locations, movement distances were quantified between the <span class="hlt">glacier</span> locations. Movement distances were then compared to see if any correlation existed between <span class="hlt">glaciers</span> with similar or dissimilar terminal terrain conditions. The Global Land Ice Measurement from Space (GLIMS) data was used as a starting point from which <span class="hlt">glacier</span> movement was measured for Baird, Patterson, and LeConte <span class="hlt">Glaciers</span> only as the Shakes <span class="hlt">Glacier</span> is currently not included in the GLIMS database. The National Oceanographic and Atmospheric Administration (NOAA) temperature data collected at the Petersburg, Alaska, meteorological station (from January 1, 1973 to December 31, 2009) were used to help in the understanding of the climatic condition in this area and potential impact on <span class="hlt">glaciers</span> terminus. Results show that <span class="hlt">glaciers</span> with similar terminal terrain conditions (Patterson and Shakes <span class="hlt">Glaciers</span>) and <span class="hlt">glaciers</span> with dissimilar terminal terrain conditions (Baird, Patterson, and LeConte <span class="hlt">Glaciers</span>) did not exhibit similar movement rates</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015TCry....9.2201P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015TCry....9.2201P"><span>Revealing <span class="hlt">glacier</span> flow and surge dynamics from animated satellite image sequences: examples from the Karakoram</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Paul, F.</p> <p>2015-11-01</p> <p>Although animated images are very popular on the internet, they have so far found only limited use for glaciological applications. With long time series of satellite images becoming increasingly available and <span class="hlt">glaciers</span> being well recognized for their rapid changes and variable flow dynamics, animated sequences of multiple satellite images reveal <span class="hlt">glacier</span> dynamics in a time-lapse mode, making the otherwise slow changes of <span class="hlt">glacier</span> movement visible and understandable to the wider public. For this study, animated image sequences were created for four regions in the central Karakoram mountain range over a 25-year time period (1990-2015) from freely available image quick-looks of orthorectified Landsat scenes. The animations play automatically in a web browser and reveal highly complex patterns of <span class="hlt">glacier</span> flow and surge dynamics that are difficult to obtain by other methods. In contrast to other regions, surging <span class="hlt">glaciers</span> in the Karakoram are often small (10 km2 or less), steep, debris-free, and advance for several years to decades at relatively low annual rates (about 100 m a-1). These characteristics overlap with those of <span class="hlt">non</span>-surge-type <span class="hlt">glaciers</span>, making a clear identification difficult. However, as in other regions, the surging <span class="hlt">glaciers</span> in the central Karakoram also show sudden increases of flow velocity and mass waves travelling down <span class="hlt">glacier</span>. The surges of individual <span class="hlt">glaciers</span> are generally out of phase, indicating a limited climatic control on their dynamics. On the other hand, nearly all other <span class="hlt">glaciers</span> in the region are either stable or slightly advancing, indicating balanced or even positive mass budgets over the past few decades.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4981079','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4981079"><span>Dynamics of <span class="hlt">glacier</span> calving at the ungrounded margin of Helheim <span class="hlt">Glacier</span>, southeast Greenland</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Selmes, Nick; James, Timothy D.; Edwards, Stuart; Martin, Ian; O'Farrell, Timothy; Aspey, Robin; Rutt, Ian; Nettles, Meredith; Baugé, Tim</p> <p>2015-01-01</p> <p>Abstract During summer 2013 we installed a network of 19 GPS nodes at the ungrounded margin of Helheim <span class="hlt">Glacier</span> in southeast Greenland together with three cameras to study iceberg calving mechanisms. The network collected data at rates up to every 7 s and was designed to be robust to loss of nodes as the <span class="hlt">glacier</span> calved. Data collection covered 55 days, and many nodes survived in locations right at the <span class="hlt">glacier</span> front to the time of iceberg calving. The observations included a number of significant calving events, and as a consequence the <span class="hlt">glacier</span> retreated ~1.5 km. The data provide real‐time, high‐frequency observations in unprecedented proximity to the calving front. The <span class="hlt">glacier</span> calved by a process of buoyancy‐force‐induced crevassing in which the ice downglacier of flexion zones rotates upward because it is out of buoyant equilibrium. Calving then occurs back to the flexion zone. This calving process provides a compelling and complete explanation for the data. Tracking of oblique camera images allows identification and characterisation of the flexion zones and their propagation downglacier. Interpretation of the GPS data and camera data in combination allows us to place constraints on the height of the basal cavity that forms beneath the rotating ice downglacier of the flexion zone before calving. The flexion zones are probably formed by the exploitation of basal crevasses, and theoretical considerations suggest that their propagation is strongly enhanced when the <span class="hlt">glacier</span> base is deeper than buoyant equilibrium. Thus, this calving mechanism is likely to dominate whenever such geometry occurs and is of increasing importance in Greenland. PMID:27570721</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70027341','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70027341"><span>The dynamic response of Kennicott <span class="hlt">Glacier</span>, Alaska, USA, to the Hidden Creek Lake outburst flood</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Anderson, R. Scott; Walder, J.S.; Anderson, S.P.; Trabant, D.C.; Fountain, A.G.</p> <p>2005-01-01</p> <p><span class="hlt">Glacier</span> sliding is commonly linked with elevated water pressure at the <span class="hlt">glacier</span> bed. Ice surface motion during a 3 week period encompassing an outburst of ice-dammed Hidden Creek Lake (HCL) at Kennicott <span class="hlt">Glacier</span>, Alaska, USA, showed enhanced sliding during the flood. Two stakes, 1.2 km from HCL, revealed increased speed in two episodes, both associated with uplift of the ice surface relative to the trajectory of bed-parallel motion. Uplift of the surface began 12 days before the flood, initially stabilizing at a value of 0.25 m. Two days after lake drainage began, further uplift (reaching 0.4 m) occurred while surface speed peaked at 1.2 m d-1. Maximum surface uplift coincided with peak discharge from HCL, high water level in a down-<span class="hlt">glacier</span> ice-marginal <span class="hlt">basin</span>, and low solute concentrations in the Kennicott River. Each of these records is consistent with high subglacial water pressure. We interpret the ice surface motion as arising from sliding up backs of bumps on the bed, which enlarges cavities and produces bed separation. The outburst increased water pressure over a broad region, promoting sliding, inhibiting cavity closure, and blocking drainage of solute-rich water from the distributed system. Pressure drop upon termination of the outburst drained water from and depressurized the distributed system, reducing sliding speeds. Expanded cavities then collapsed with a 1 day time-scale set by the local ice thickness.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/bul/1995/cc/pdf/bul1995cc.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/bul/1995/cc/pdf/bul1995cc.pdf"><span>Characterization of the Hosgri Fault Zone and <span class="hlt">adjacent</span> structures in the offshore Santa Maria <span class="hlt">Basin</span>, south-central California: Chapter CC of Evolution of sedimentary <span class="hlt">basins</span>/onshore oil and gas investigations - Santa Maria province</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Willingham, C. Richard; Rietman, Jan D.; Heck, Ronald G.; Lettis, William R.</p> <p>2013-01-01</p> <p>The Hosgri Fault Zone trends subparallel to the south-central California coast for 110 km from north of Point Estero to south of Purisima Point and forms the eastern margin of the present offshore Santa Maria <span class="hlt">Basin</span>. Knowledge of the attributes of the Hosgri Fault Zone is important for petroleum development, seismic engineering, and environmental planning in the region. Because it lies offshore along its entire reach, our characterizations of the Hosgri Fault Zone and <span class="hlt">adjacent</span> structures are primarily based on the analysis of over 10,000 km of common-depth-point marine seismic reflection data collected from a 5,000-km2 area of the central and eastern parts of the offshore Santa Maria <span class="hlt">Basin</span>. We describe and illustrate the along-strike and downdip geometry of the Hosgri Fault Zone over its entire length and provide examples of interpreted seismic reflection records and a map of the structural trends of the fault zone and <span class="hlt">adjacent</span> structures in the eastern offshore Santa Maria <span class="hlt">Basin</span>. The seismic data are integrated with offshore well and seafloor geologic data to describe the age and seismic appearance of offshore geologic units and marker horizons. We develop a <span class="hlt">basin</span>-wide seismic velocity model for depth conversions and map three major unconformities along the eastern offshore Santa Maria <span class="hlt">Basin</span>. Accompanying plates include maps that are also presented as figures in the report. Appendix A provides microfossil data from selected wells and appendix B includes uninterpreted copies of the annotated seismic record sections illustrated in the chapter. Features of the Hosgri Fault Zone documented in this investigation are suggestive of both lateral and reverse slip. Characteristics indicative of lateral slip include (1) the linear to curvilinear character of the mapped trace of the fault zone, (2) changes in structural trend along and across the fault zone that diminish in magnitude toward the ends of the fault zone, (3) localized compressional and extensional structures</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.3046S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.3046S"><span>Spatial features of <span class="hlt">glacier</span> changes in the Barents-Kara Sector</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sharov, A. I.; Schöner, W.; Pail, R.</p> <p>2009-04-01</p> <p>In the 1950s, the total area of <span class="hlt">glaciers</span> occupying separate islands and archipelagos of the Barents and Kara seas exceeded 92,300 km² (Atlas of the Arctic 1985). The overall <span class="hlt">glacier</span> volume reached 20,140 km³ and the average ice thickness was given as 218 m. Our recent remote sensing studies and mass-balance estimates using spaceborne ASTER and LANDSAT imagery, ERS and JERS radar interferometric mosaics, and ICESat altimetry data revealed that, in the 2000s, the areal extent and volume of Barents-Kara glaciation amounted to 86,200±200 km² and 19,330±20 km³, respectively. The annual loss of land ice influenced by severe climate change in longitudinal direction was determined at approx. 8 km³/a in Svalbard, 4 km³/a both in the Franz Josef Land and Novaya Zemlya archipelagos, and less than 0.3 km³/a in Severnaya Zemlya over the past 50 years. The average ice thickness of remaining glaciation increased to 224 m. This fact was explained by rapid disintegration of thinner <span class="hlt">glacier</span> margins and essential accumulation of snow at higher <span class="hlt">glacier</span> elevations. Both effects were clearly visible in the series of satellite image maps of <span class="hlt">glacier</span> elevation changes generated within the framework of the INTEGRAL, SMARAGD and ICEAGE research projects. These maps can be accessed at http://joanneum.dib.at/integral or smaragd (cd results). The largest negative elevation changes were typically detected in the seaward <span class="hlt">basins</span> of fast-flowing outlet <span class="hlt">glaciers</span>, both at their fronts and tops. Ablation processes were stronger manifested on southern slopes of ice caps, while the accumulation of snow was generally higher on northern slopes so that main ice divides "shifted" to the north. The largest positive elevation changes (about 100 m) were found in the central part of the study region in the accumulation areas of the biggest ice caps, such as Northern Ice Cap in Novaya Zemlya, Tyndall and Windy ice domes in Franz Josef Land, and Kvitoyjokulen at Kvitøya. The sides of these <span class="hlt">glaciers</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GPC...165..137V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GPC...165..137V"><span>Early 21st century spatially detailed elevation changes of Jammu and Kashmir <span class="hlt">glaciers</span> (Karakoram-Himalaya)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vijay, Saurabh; Braun, Matthias</p> <p>2018-06-01</p> <p>Although a number of studies indicate the regional heterogeneity of the <span class="hlt">glacier</span> elevation and mass changes in high-mountain Asia in the early 21st century, little is known about these changes with high spatial detail for some of the regions. In this study we present respective <span class="hlt">glacier</span> elevation and mass change estimates in the Indian state of Jammu and Kashmir (JK) for the period 2000-2012. Our estimates are based on the interferometric analysis of SRTM DEM and the bistatic TanDEM-X data. On an average the JK East (Karakoram) <span class="hlt">glaciers</span> showed less negative elevation changes (- 0.19 ± 0.22 m yr-1) compared to the JK West (Himalaya) <span class="hlt">glaciers</span> (- 0.50 ± 0.28 m yr-1). This agrees very well with previous studies that show a transition from larger changes in the western Himalaya to a steady-state situation in the Karakoram. We observe distinct elevation change patterns on a <span class="hlt">glacier</span> scale that is most likely linked to debris insulation and the enhanced ice melting due to supraglacial lakes, ponds and ice cliffs. We also found 16 surge-type <span class="hlt">glaciers</span> in the JK East which were not documented before. In total, 25 <span class="hlt">glaciers</span> surged and 4 others appeared to be in a quiescent phase in the observation period. Our results also reveal that the <span class="hlt">glacier</span>-averaged elevation change rates of surge-type and <span class="hlt">non</span> surge-type <span class="hlt">glaciers</span> in the JK East region are not significantly different.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70034952','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70034952"><span>Implications for the dynamic health of a <span class="hlt">glacier</span> from comparison of conventional and reference-surface balances</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Harrison, W.D.; Cox, L.H.; Hock, R.; March, R.S.; Pettit, E.C.</p> <p>2009-01-01</p> <p>Conventional and reference-surface mass-balance data from Gulkana and Wolverine <span class="hlt">Glaciers</span>, Alaska, USA, are used to address the questions of how rapidly these <span class="hlt">glaciers</span> are adjusting (or 'responding') to climate, whether their responses are stable, and whether the <span class="hlt">glaciers</span> are likely to survive in today's climate. Instability means that a <span class="hlt">glacier</span> will eventually vanish, or at least become greatly reduced in volume, if the climate stabilizes at its present state. A simple <span class="hlt">non</span>-linear theory of response is presented for the analysis. The response of Gulkana <span class="hlt">Glacier</span> is characterized by a timescale of several decades, but its stability and therefore its survival in today's climate are uncertain. Wolverine seems to be responding to climate more slowly, on the timescale of one to several centuries. Its stability is also uncertain, but a slower response time would make it more susceptible to climate changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMEP53D1064S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMEP53D1064S"><span>Climate change impacts on <span class="hlt">glaciers</span> and runoff in Tien Shan (Central Asia)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sorg, A. F.; Bolch, T.; Stoffel, M.; Solomina, O.; Beniston, M.</p> <p>2012-12-01</p> <p>Climate-driven changes in <span class="hlt">glacier</span>-fed streamflow regimes have direct implications on freshwater supply, irrigation and hydropower potential. Reliable information about current and future glaciation and runoff is crucial for water allocation and, hence, for social and ecological stability. Although the impacts of climate change on glaciation and runoff have been addressed in previous work undertaken in the Tien Shan (known as the 'water tower of Central Asia'), a coherent, regional perspective of these findings has not been presented until now. In our study, we explore the range of changes in glaciation in different climatic regions of the Tien Shan based on existing data. We show that the majority of Tien Shan <span class="hlt">glaciers</span> experienced accelerated <span class="hlt">glacier</span> wasting since the mid-1970s and that <span class="hlt">glacier</span> shrinkage is most pronounced in peripheral, lower-elevation ranges near the densely populated forelands, where summers are dry and where snow and glacial meltwater is essential for water availability. The annual <span class="hlt">glacier</span> area shrinkage rates since the middle of the twentieth century are 0.38-0.76% per year in the outer ranges, 0.15-0.40% per year in the inner ranges and 0.05-0.31% per year in the eastern ranges. This regionally <span class="hlt">non</span>-uniform response to climate change implies that <span class="hlt">glacier</span> shrinkage is less severe in the continental inner ranges than in the more humid outer ranges. <span class="hlt">Glaciers</span> in the inner ranges react with larger time lags to climate change, because accumulation and thus mass turnover of the mainly cold <span class="hlt">glaciers</span> are relatively small. Moreover, shrinkage is especially pronounced on small or fragmented <span class="hlt">glaciers</span>, which are widely represented in the outer regions. The relative insensitivity of <span class="hlt">glaciers</span> in the inner ranges is further accentuated by the higher average altitude, as the equilibrium line altitude ranges from 3'500 to 3'600 masl in the outer ranges to 4'400 masl in the inner ranges. For our study, we used <span class="hlt">glacier</span> change assessments based both on direct data</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27147435','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27147435"><span>Quantitative Evaluation of Heavy Metals and Trace Elements in the Urinary Bladder: Comparison Between Cancerous, <span class="hlt">Adjacent</span> <span class="hlt">Non</span>-cancerous and Normal Cadaveric Tissue.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Abdel-Gawad, Mahmoud; Elsobky, Emad; Shalaby, Mahmoud M; Abd-Elhameed, Mohamed; Abdel-Rahim, Mona; Ali-El-Dein, Bedeir</p> <p>2016-12-01</p> <p>The role of heavy metals and trace elements (HMTE) in the development of some cancers has been previously reported. Bladder carcinoma is a frequent malignancy of the urinary tract. The most common risk factors for bladder cancer are exposure to industrial carcinogens, cigarette smoking, gender, and possibly diet. The aim of this study was to evaluate HTME concentrations in the cancerous and <span class="hlt">adjacent</span> <span class="hlt">non</span>-cancerous tissues and compare them with those of normal cadaveric bladder. This prospective study included 102 paired samples of full-thickness cancer and <span class="hlt">adjacent</span> <span class="hlt">non</span>-cancerous bladder tissues of radical cystectomy (RC) specimens that were histologically proven as invasive bladder cancer (MIBC). We used 17 matched controls of <span class="hlt">non</span>-malignant bladder tissue samples from cadavers. All samples were processed and evaluated for the concentration of 22 HMTE by using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Outcome analysis was made by the Mann-Whitney U, chi-square, Kruskal-Wallis, and Wilcoxon signed ranks tests. When compared with cadaveric control or cancerous, the <span class="hlt">adjacent</span> <span class="hlt">non</span>-cancerous tissue had higher levels of six elements (arsenic, lead, selenium, strontium, zinc, and aluminum), and when compared with the control alone, it had a higher concentration of calcium, cadmium, chromium, potassium, magnesium, and nickel. The cancerous tissue had a higher concentration of cadmium, lead, chromium, calcium, potassium, phosphorous, magnesium, nickel, selenium, strontium, and zinc than cadaveric control. Boron level was higher in cadaveric control than cancerous and <span class="hlt">adjacent</span> <span class="hlt">non</span>-cancerous tissue. Cadmium level was higher in cancerous tissue with node-positive than node-negative cases. The high concentrations of cadmium, lead, chromium, nickel, and zinc, in the cancerous together with arsenic in the <span class="hlt">adjacent</span> <span class="hlt">non</span>-cancerous tissues of RC specimens suggest a pathogenic role of these elements in BC. However, further work-up is needed to support this</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004GPC....42..279S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004GPC....42..279S"><span><span class="hlt">Glacier</span> ice mass fluctuations and fault instability in tectonically active Southern Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sauber, Jeanne M.; Molnia, Bruce F.</p> <p>2004-07-01</p> <p>Across the plate boundary zone in south central Alaska, tectonic strain rates are high in a region that includes large <span class="hlt">glaciers</span> undergoing wastage (<span class="hlt">glacier</span> retreat and thinning) and surges. For the coastal region between the Bering and Malaspina <span class="hlt">Glaciers</span>, the average ice mass thickness changes between 1995 and 2000 range from 1 to 5 m/year. These ice changes caused solid Earth displacements in our study region with predicted values of -10 to 50 mm in the vertical and predicted horizontal displacements of 0-10 mm at variable orientations. Relative to stable North America, observed horizontal rates of tectonic deformation range from 10 to 40 mm/year to the north-northwest and the predicted tectonic uplift rates range from approximately 0 mm/year near the Gulf of Alaska coast to 12 mm/year further inland. The ice mass changes between 1995 and 2000 resulted in discernible changes in the Global Positioning System (GPS) measured station positions of one site (ISLE) located <span class="hlt">adjacent</span> to the Bagley Ice Valley and at one site, DON, located south of the Bering <span class="hlt">Glacier</span> terminus. In addition to modifying the surface displacements rates, we evaluated the influence ice changes during the Bering <span class="hlt">glacier</span> surge cycle had on the background seismic rate. We found an increase in the number of earthquakes ( ML≥2.5) and seismic rate associated with ice thinning and a decrease in the number of earthquakes and seismic rate associated with ice thickening. These results support the hypothesis that ice mass changes can modulate the background seismic rate. During the last century, wastage of the coastal <span class="hlt">glaciers</span> in the Icy Bay and Malaspina region indicates thinning of hundreds of meters and in areas of major retreat, maximum losses of ice thickness approaching 1 km. Between the 1899 Yakataga and Yakutat earthquakes ( Mw=8.1, 8.1) and prior to the 1979 St. Elias earthquake ( Ms=7.2), the plate interface below Icy Bay was locked and tectonic strain accumulated. We used estimated ice mass</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70026696','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70026696"><span><span class="hlt">Glacier</span> ice mass fluctuations and fault instability in tectonically active Southern Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sauber, J.M.; Molnia, B.F.</p> <p>2004-01-01</p> <p>Across the plate boundary zone in south central Alaska, tectonic strain rates are high in a region that includes large <span class="hlt">glaciers</span> undergoing wastage (<span class="hlt">glacier</span> retreat and thinning) and surges. For the coastal region between the Bering and Malaspina <span class="hlt">Glaciers</span>, the average ice mass thickness changes between 1995 and 2000 range from 1 to 5 m/year. These ice changes caused solid Earth displacements in our study region with predicted values of -10 to 50 mm in the vertical and predicted horizontal displacements of 0-10 mm at variable orientations. Relative to stable North America, observed horizontal rates of tectonic deformation range from 10 to 40 mm/year to the north-northwest and the predicted tectonic uplift rates range from approximately 0 mm/year near the Gulf of Alaska coast to 12 mm/year further inland. The ice mass changes between 1995 and 2000 resulted in discernible changes in the Global Positioning System (GPS) measured station positions of one site (ISLE) located <span class="hlt">adjacent</span> to the Bagley Ice Valley and at one site, DON, located south of the Bering <span class="hlt">Glacier</span> terminus. In addition to modifying the surface displacements rates, we evaluated the influence ice changes during the Bering <span class="hlt">glacier</span> surge cycle had on the background seismic rate. We found an increase in the number of earthquakes (ML???2.5) and seismic rate associated with ice thinning and a decrease in the number of earthquakes and seismic rate associated with ice thickening. These results support the hypothesis that ice mass changes can modulate the background seismic rate. During the last century, wastage of the coastal <span class="hlt">glaciers</span> in the Icy Bay and Malaspina region indicates thinning of hundreds of meters and in areas of major retreat, maximum losses of ice thickness approaching 1 km. Between the 1899 Yakataga and Yakutat earthquakes (Mw=8.1, 8.1) and prior to the 1979 St. Elias earthquake (M s=7.2), the plate interface below Icy Bay was locked and tectonic strain accumulated. We used estimated ice mass</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1212086L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1212086L"><span>A new satellite-derived <span class="hlt">glacier</span> inventory for Western Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Le Bris, Raymond; Frey, Holger; Paul, Frank; Bolch, Tobias</p> <p>2010-05-01</p> <p><span class="hlt">Glaciers</span> and ice caps are essential components of studies related to climate change impact assessment. <span class="hlt">Glacier</span> inventories provide the required baseline data to perform the related analysis in a consistent and spatially representative manner. In particular, the calculation of the current and future contribution to global sea-level rise from heavily <span class="hlt">glacierized</span> regions is a major demand. One of the regions, where strong mass losses and geometric changes of <span class="hlt">glaciers</span> have been observed recently is Alaska. Unfortunately, the digitally available data base of <span class="hlt">glacier</span> extent is quite rough and based on rather old maps from the 1960s. Accordingly, the related calculations and extrapolations are imprecise and an updated <span class="hlt">glacier</span> inventory is urgently required. Here we present first results of a new <span class="hlt">glacier</span> inventory for Western Alaska that is prepared in the framework of the ESA project Glob<span class="hlt">Glacier</span> and is based on freely available orthorectified Landsat TM and ETM+ scenes from USGS. The analysed region covers the Tordrillo, Chigmit and Chugach Mts. as well as the Kenai Peninsula. In total, 8 scenes acquired between 2002 and 2009 were used covering c. 20.420 km2 of <span class="hlt">glaciers</span>. All <span class="hlt">glacier</span> types are present in this region, incl. outlet <span class="hlt">glaciers</span> from icefields, <span class="hlt">glacier</span> clad volcanoes, and calving <span class="hlt">glaciers</span>. While well established automated <span class="hlt">glacier</span> mapping techniques (band rationing) are applied to map clean and slightly dirty <span class="hlt">glacier</span> ice, many <span class="hlt">glaciers</span> are covered by debris or volcanic ash and outlines need manual corrections during post-processing. Prior to the calculation of drainage divides from DEM-based watershed analysis, we performed a cross-comparative analysis of DEMs from USGS, ASTER (GDEM) and SRTM 1 for Kenai Peninsula. This resulted in the decision to use the USGS DEM for calculating the drainage divides and most of the topographic inventory parameters, and the more recent GDEM to derive minimum elevation for each <span class="hlt">glacier</span>. A first statistical analysis of the results</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.8467K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.8467K"><span>Relict rock <span class="hlt">glaciers</span> in alpine catchments: A regional study in Central Austria</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kellerer-Pirklbauer, Andreas; Pauritsch, Marcus; Winkler, Gerfried</p> <p>2013-04-01</p> <p>Alpine catchments represent an important freshwater source in many regions. Catchments in the subalpine to nival altitudinal levels are generally characterised by higher precipitation, lower evapotranspiration and consequently higher discharge rates compared to lower elevated areas of the montane and foothill levels of the same region. Particularly in crystalline mountain regions in the mid- to high latitudes glacial and periglacial sediments cover larger areas and form important aquifers in alpine catchments. Typical periglacial landforms in mountain areas are rock <span class="hlt">glaciers</span>. Relict rock <span class="hlt">glaciers</span> consist of sediment accumulations without permafrost at present. This rock <span class="hlt">glacier</span> type has a strong influence on water storage capacities and discharge behaviour of the catchments. The hydraulic properties of rock <span class="hlt">glaciers</span> have a positive impact on flood-risk reduction and the riparian ecology below rock <span class="hlt">glacier</span> springs during dry periods. Furthermore, the exceptional high discharge rates at springs at the front of relict rock <span class="hlt">glaciers</span> compared to nearby <span class="hlt">non</span>-rock <span class="hlt">glacier</span> springs are also of economic interest. Knowledge about morphometric characteristics of rock <span class="hlt">glacier</span> catchments helps to increase the understanding of the groundwater system and discharge dynamics of rock <span class="hlt">glaciers</span>. In this context the main objectives of our study are (a) to assess and quantitatively describe rock <span class="hlt">glacier</span> catchments at a regional scale by analysing different morphometric parameters of the catchments and (b) to combine the rock <span class="hlt">glacier</span> catchment properties with water balance data. In doing so, at first an inventory of 295 rock <span class="hlt">glacier</span> catchments was established for the 2440 km² large study area (Niedere Tauern Range, Styria) in Central Austria ranging from 590 to 2862 m a.s.l.. In a second step, the inventory data were combined with area-wide precipitation, discharge and evapotranspiration data. Results reveal that 108 km² or 4.4% of the entire study area belongs to rock <span class="hlt">glacier</span> catchments</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013E%26PSL.361...16L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013E%26PSL.361...16L"><span>Timing of the last glaciation and subsequent deglaciation in the Ruby Mountains, Great <span class="hlt">Basin</span>, USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Laabs, Benjamin J. C.; Munroe, Jeffrey S.; Best, Laura C.; Caffee, Marc W.</p> <p>2013-01-01</p> <p>The timing of the last Pleistocene glaciation in western North America is becoming increasingly well understood, largely due to improved methods of obtaining numerical ages of glacial deposits and landforms. Among these, cosmogenic radionuclide surface-exposure dating has been widely applied to moraines of mountain <span class="hlt">glaciers</span>, providing the framework for understanding terrestrial climate change during and since the last glaciation in western North America. During the Late Pleistocene, the Great <span class="hlt">Basin</span> of the western United States hosted numerous mountain <span class="hlt">glaciers</span>, the deposits of which can provide valuable records of past climate changes if their ages can be precisely determined. In this study, twenty-nine cosmogenic radionuclide 10Be surface-exposure ages from a suite of moraines in Seitz Canyon, western Ruby Mountains, limit the timing of the last glacial episode in the interior Great <span class="hlt">Basin</span>, known as the Angel Lake Glaciation. Results indicate that deposition of a terminal moraine and two recessional moraines began just prior to ˜20.5 ka and continued until ˜20.0 ka. Retreat from the next younger recessional moraine began at ˜17.2 ka, and final deglaciation began at ˜14.8 ka. These ages are broadly consistent with cosmogenic surface-exposure ages from the eastern Sierra Nevada and the western Wasatch Mountains, in the western and eastern extremes of the Great <span class="hlt">Basin</span> respectively. Furthermore, these ages suggest that the valley <span class="hlt">glacier</span> in Seitz Canyon was at or near its maximum extent before and during the hydrologic maxima of Pleistocene lakes in the Great <span class="hlt">Basin</span>, supporting previous suggestions that a cool and wet climate persisted in this region during the early part of the last glacial-interglacial transition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018TCry...12..103W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018TCry...12..103W"><span>Recent <span class="hlt">glacier</span> mass balance and area changes in the Kangri Karpo Mountains from DEMs and <span class="hlt">glacier</span> inventories</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Kunpeng; Liu, Shiyin; Jiang, Zongli; Xu, Junli; Wei, Junfeng; Guo, Wanqin</p> <p>2018-01-01</p> <p>Due to the influence of the Indian monsoon, the Kangri Karpo Mountains in the south-east of the Tibetan Plateau is in the most humid and one of the most important and concentrated regions containing maritime (temperate) <span class="hlt">glaciers</span>. <span class="hlt">Glacier</span> mass loss in the Kangri Karpo is an important contributor to global mean sea level rise, and changes run-off distribution, increasing the risk of glacial-lake outburst floods (GLOFs). Because of its inaccessibility and high labour costs, information about the Kangri Karpo <span class="hlt">glaciers</span> is still limited. Using geodetic methods based on digital elevation models (DEMs) derived from 1980 topographic maps from the Shuttle Radar Topography Mission (SRTM) (2000) and from TerraSAR-X/TanDEM-X (2014), this study has determined <span class="hlt">glacier</span> elevation changes. <span class="hlt">Glacier</span> area and length changes between 1980 and 2015 were derived from topographical maps and Landsat TM/ETM+/OLI images. Results show that the Kangri Karpo contained 1166 <span class="hlt">glaciers</span> with an area of 2048.50 ± 48.65 km2 in 2015. Ice cover diminished by 679.51 ± 59.49 km2 (24.9 ± 2.2 %) or 0.71 ± 0.06 % a-1 from 1980 to 2015, although nine <span class="hlt">glaciers</span> advanced. A <span class="hlt">glacierized</span> area of 788.28 km2, derived from DEM differencing, experienced a mean mass loss of 0.46 ± 0.08 m w.e. a-1 from 1980 to 2014. Shrinkage and mass loss accelerated significantly from 2000 to 2015 compared to 1980-2000, consistent with a warming climate.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004ggav.rept......','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004ggav.rept......"><span>Geenland <span class="hlt">Glacier</span> Albedo Variability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p></p> <p>2004-01-01</p> <p>The program for Arctic Regional Climate Assessment (PARCA) is a NASA-funded project with the prime goal of addressing the mass balance of the Greenland ice sheet. Since the formal initiation of the program in 1995, there has been a significant improvement in the estimates of the mass balance of the ice sheet. Results from this program reveal that the high-elevation regions of the ice sheet are approximately in balance, but the margins are thinning. Laser surveys reveal significant thinning along 70 percent of the ice sheet periphery below 2000 m elevations, and in at least one outlet <span class="hlt">glacier</span>, Kangerdlugssuaq in southeast Greenland, thinning has been as much as 10 m/yr. This study examines the albedo variability in four outlet <span class="hlt">glaciers</span> to help separate out the relative contributions of surface melting versus ice dynamics to the recent mass balance changes. Analysis of AVHRR Polar Pathfinder albedo shows that at the Petermann and Jakobshavn <span class="hlt">glaciers</span>, there has been a negative trend in albedo at the <span class="hlt">glacier</span> terminus from 1981 to 2000, whereas the Stor+strommen and Kangerdlugssuaq <span class="hlt">glaciers</span> show slightly positive trends in albedo. These findings are consistent with recent observations of melt extent from passive microwave data which show more melt on the western side of Greenland and slightly less on the eastern side. Significance of albedo trends will depend on where and when the albedo changes occur. Since the majority of surface melt occurs in the shallow sloping western margin of the ice sheet where the shortwave radiation dominates the energy balance in summer (e.g. Jakobshavn region) this region will be more sensitive to changes in albedo than in regions where this is not the case. Near the Jakobshavn <span class="hlt">glacier</span>, even larger changes in albedo have been observed, with decreases as much as 20 percent per decade.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040050637','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040050637"><span>Greenland <span class="hlt">Glacier</span> Albedo Variability</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>The program for Arctic Regional Climate Assessment (PARCA) is a NASA-funded project with the prime goal of addressing the mass balance of the Greenland ice sheet. Since the formal initiation of the program in 1995, there has been a significant improvement in the estimates of the mass balance of the ice sheet. Results from this program reveal that the high-elevation regions of the ice sheet are approximately in balance, but the margins are thinning. Laser surveys reveal significant thinning along 70 percent of the ice sheet periphery below 2000 m elevations, and in at least one outlet <span class="hlt">glacier</span>, Kangerdlugssuaq in southeast Greenland, thinning has been as much as 10 m/yr. This study examines the albedo variability in four outlet <span class="hlt">glaciers</span> to help separate out the relative contributions of surface melting versus ice dynamics to the recent mass balance changes. Analysis of AVHRR Polar Pathfinder albedo shows that at the Petermann and Jakobshavn <span class="hlt">glaciers</span>, there has been a negative trend in albedo at the <span class="hlt">glacier</span> terminus from 1981 to 2000, whereas the Stor+strommen and Kangerdlugssuaq <span class="hlt">glaciers</span> show slightly positive trends in albedo. These findings are consistent with recent observations of melt extent from passive microwave data which show more melt on the western side of Greenland and slightly less on the eastern side. Significance of albedo trends will depend on where and when the albedo changes occur. Since the majority of surface melt occurs in the shallow sloping western margin of the ice sheet where the shortwave radiation dominates the energy balance in summer (e.g. Jakobshavn region) this region will be more sensitive to changes in albedo than in regions where this is not the case. Near the Jakobshavn <span class="hlt">glacier</span>, even larger changes in albedo have been observed, with decreases as much as 20 percent per decade.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFMIP52A0750K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFMIP52A0750K"><span>Five 'Supercool' Icelandic <span class="hlt">Glaciers</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Knudsen, O.; Roberts, M. J.; Roberts, M. J.; Tweed, F. S.; Russell, A. J.; Lawson, D. E.; Larson, G. J.; Evenson, E. B.; Bjornsson, H.</p> <p>2001-12-01</p> <p>Sediment entrainment by glaciohydraulic supercooling has recently been demonstrated as an effective process at Matanuska <span class="hlt">glacier</span>, Alaska. Although subfreezing meltwater temperatures have been recorded at several Alaskan <span class="hlt">glaciers</span>, the link between supercooling and sediment accretion remains confined to Matanuska. This study presents evidence of glaciohydraulic supercooling and associated basal ice formation from five Icelandic <span class="hlt">glaciers</span>: Skeidarárjökull, Skaftafellsjökull, Kvíárjökull, Flaájökull, and Hoffellsjökull. These observations provide the best example to-date of glaciohydraulic supercooling and related sediment accretion outside Alaska. Fieldwork undertaken in March, July and August 2001 confirmed that giant terraces of frazil ice, diagnostic of the presence of supercooled water, are forming around subglacial artesian vents. Frazil flocs retrieved from these vents contained localised sandy nodules at ice crystal boundaries. During periods of high discharge, sediment-laden frazil flocs adhere to the inner walls of vents, and continue to trap suspended sediment. Bands of debris-rich frazil ice, representing former vents, are texturally similar to basal ice exposures at the <span class="hlt">glacier</span> margins, implying a process-form relationship between glaciohydraulic freeze-on and basal ice formation. It is hypothesised that glaciohydraulic supercooling is generating thick sequences of basal ice. Observations also confirm that in situ melting of basal ice creates thick sedimentary sequences, as sediment structures present in the basal ice can be clearly traced into ice-marginal ridges. Glaciohydraulic supercooling is an effective sediment entrainment mechanism at Icelandic <span class="hlt">glaciers</span>. Supercooling has the capacity to generate thick sequences of basal ice and the sediments present in basal ice can be preserved. These findings are incompatible with established theories of intraglacial sediment entrainment and basal ice formation; instead, they concur with, and extend, the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015QSRv..114...78W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015QSRv..114...78W"><span>Reconstructing Holocene <span class="hlt">glacier</span> activity at Langfjordjøkelen, Arctic Norway, using multi-proxy fingerprinting of distal <span class="hlt">glacier</span>-fed lake sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wittmeier, Hella E.; Bakke, Jostein; Vasskog, Kristian; Trachsel, Mathias</p> <p>2015-04-01</p> <p>Late Glacial and Holocene <span class="hlt">glacier</span> fluctuations are important indicators of climate variability in the northern polar region and contain knowledge vital to understanding and predicting present and future climate changes. However, there still is a lack of robustly dated terrestrial climate records from Arctic Norway. Here, we present a high-resolution relative <span class="hlt">glacier</span> activity record covering the past ∼10,000 cal. a BP from the northern outlet of the Langfjordjøkelen ice cap in Arctic Norway. This record is reconstructed from detailed geomorphic mapping, multi-proxy sedimentary fingerprinting and analyses of distal <span class="hlt">glacier</span>-fed lake sediments. We used Principal Component Analysis to characterize sediments of glacial origin and trace them in a chain of downstream lakes. Of the variability in the sediment record of the uppermost Lake Jøkelvatnet, 73% can be explained by the first Principal Component axis and tied directly to upstream <span class="hlt">glacier</span> erosion, whereas the glacial signal becomes weaker in the more distal Lakes Store Rundvatnet and Storvatnet. Magnetic susceptibility and titanium count rates were found to be the most suitable indicators of Holocene <span class="hlt">glacier</span> activity in the distal <span class="hlt">glacier</span>-fed lakes. The complete deglaciation of the valley of Sør-Tverrfjorddalen occurred ∼10,000 cal. a BP, followed by a reduced or absent <span class="hlt">glacier</span> during the Holocene Thermal Optimum. The Langfjordjøkelen ice cap reformed with the onset of the Neoglacial ∼4100 cal. a BP, and the gradually increasing <span class="hlt">glacier</span> activity culminated at the end of the Little Ice Age in the early 20th century. Over the past 2000 cal. a BP, the record reflects frequent high-amplitude <span class="hlt">glacier</span> fluctuations. Periods of reduced <span class="hlt">glacier</span> activity were centered around 1880, 1600, 1250 and 950 cal. a BP, while intervals of increased <span class="hlt">glacier</span> activity occurred around 1680, 1090, 440 and 25 cal. a BP. The large-scale Holocene <span class="hlt">glacier</span> activity of the Langfjordjøkelen ice cap is consistent with regional temperature</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E%26ES...74a2022F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26ES...74a2022F"><span><span class="hlt">Glacier</span> retreat of the Tian Shan and its impact on the urban growth and environment evaluated from satellite remote sensing data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fu, B. H.; Guo, Q.; Yan, F.; Zhang, J.; Shi, P. L.; Ayinuer, M.; Xue, G. L.</p> <p>2017-07-01</p> <p>The retreat of mountain <span class="hlt">glaciers</span>, notably in high Asia, provides evidence for the rise of global temperature. The mass balance is vital for the health of a <span class="hlt">glacier</span>. If the amount of frozen precipitation in the accumulation zone exceeds the quantity of glacial ice loss due to melting or lies in the ablation zone, the <span class="hlt">glacier</span> will advance. Conversely, if the accumulation is less than the ablation, the <span class="hlt">glacier</span> will retreat. <span class="hlt">Glaciers</span> in retreat will have negative mass balances, and if they do not reach an equilibrium between accumulation and ablation, will eventually disappear. Long-term changes of the mountain <span class="hlt">glaciers</span> in the Tian Shan, Central Asia, are not well constrained. Analyses of satellite remote sensing data combined with the ground observations reveal a 37.5% decline of <span class="hlt">glaciered</span> area from 1989 to 2014 in No.1 <span class="hlt">Glacier</span>, the headwaters of the Urumqi River <span class="hlt">basin</span>, Chinese Tian Shan, which could be linked to increased summer melting. The results show that the area of <span class="hlt">glaciers</span> was reduced from 31.55 km2 in 18 August 1989 to 28.66 km2 in 24 August 1994 and 19.74 km2 in 31 August 2014. The <span class="hlt">glacier</span> area was reduced by 0.47 km2/per year in recent 25 years since 1989, and the annual reduction was 1.5%. Meanwhile, the urban area of Urumqi, the biggest city of Xinjiang Uygur Autonomous Region, increased from 156 km2 in 1989 to 555 km2 in 2014. Correspondingly, the population of permanent residents increased from 1.06 million in 1989 to 3.53 million in 2014. We suggest that the decline of <span class="hlt">glacier</span> area is driven primarily by summer melting and, possibly, linked to the combined effects of the global rise in temperatures and black carbon/CO2 emission from coal-fired power plants, cement plants and petroleum chemical plants from the nearby Urumqi and surrounding regions. The continuing retreat of <span class="hlt">glaciers</span> will have a number of different quantitative impacts. Populations in the arid Central Asia regions are heavily dependent on snow and <span class="hlt">glacier</span> melt for their irrigation and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.C33C1303J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.C33C1303J"><span>The energy balance on the surface of a tropical <span class="hlt">glacier</span> tongue. Investigations on <span class="hlt">glacier</span> Artesonraju, Cordillera Blanca, Perú.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Juen, I.; Mölg, T.; Wagnon, P.; Cullen, N. J.; Kaser, G.</p> <p>2006-12-01</p> <p>The Cordillera Blanca in Perú is situated in the Outer Tropics spanning from 8 to 10 ° South. Solar incidence and air temperature show only minor seasonal variations whereas precipitation occurs mainly from October to April. An energy balance station was installed on the tongue of <span class="hlt">glacier</span> Artesonraju (4850 m a.s.l.) in March 2004. In this study each component of the energy balance on the <span class="hlt">glacier</span> surface is analysed separately over a full year, covering one dry and one wet season. During the dry season <span class="hlt">glacier</span> melt at the <span class="hlt">glacier</span> tongue is app. 0.5 m we per month. In the wet season <span class="hlt">glacier</span> melt is twice as much with 1 m we per month. This is due to higher energy fluxes and decreased sublimation during the wet season. With an energy balance model that has already been proved under tropical climate conditions (Mölg and Hardy, 2004) each energy flux is changed individually to evaluate the change in the amount of <span class="hlt">glacier</span> melt. First results indicate that a change in humidity related variables affects <span class="hlt">glacier</span> melt very differently in the dry and wet season, whereas a change in air temperature changes <span class="hlt">glacier</span> melt more constantly throughout the year.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.C21D0667A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.C21D0667A"><span>An Analysis of Mass Balance of Chilean <span class="hlt">Glaciers</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ambinakudige, S.; Tetteh, L.</p> <p>2013-12-01</p> <p><span class="hlt">Glaciers</span> in Chile range from very small glacierets found on the isolated volcanoes of northern Chile to the 13,000 sq.km Southern Patagonian Ice Field. Regular monitoring of these <span class="hlt">glaciers</span> is very important as they are considered as sensitive indicators of climate change. Millions of people's lives are dependent on these <span class="hlt">glaciers</span> for fresh water and irrigation purpose. In this study, mass balances of several Chilean <span class="hlt">glaciers</span> were estimated using Aster satellite images between 2007 and 2012. Highly accurate DEMs were created with supplementary information from IceSat data. The result indicated a negative mass balance for many <span class="hlt">glaciers</span> indicating the need for further monitoring of <span class="hlt">glaciers</span> in the Andes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://wa.water.usgs.gov/projects/glacier/data/bidlake_AGU_2010.pdf','USGSPUBS'); return false;" href="http://wa.water.usgs.gov/projects/glacier/data/bidlake_AGU_2010.pdf"><span><span class="hlt">Glacier</span> modeling in support of field observations of mass balance at South Cascade <span class="hlt">Glacier</span>, Washington, USA</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Josberger, Edward G.; Bidlake, William R.</p> <p>2010-01-01</p> <p>The long-term USGS measurement and reporting of mass balance at South Cascade <span class="hlt">Glacier</span> was assisted in balance years 2006 and 2007 by a new mass balance model. The model incorporates a temperature-index melt computation and accumulation is modeled from <span class="hlt">glacier</span> air temperature and gaged precipitation at a remote site. Mass balance modeling was used with glaciological measurements to estimate dates and magnitudes of critical mass balance phenomena. In support of the modeling, a detailed analysis was made of the "<span class="hlt">glacier</span> cooling effect" that reduces summer air temperature near the ice surface as compared to that predicted on the basis of a spatially uniform temperature lapse rate. The analysis was based on several years of data from measurements of near-surface air temperature on the <span class="hlt">glacier</span>. The 2006 and 2007 winter balances of South Cascade <span class="hlt">Glacier</span>, computed with this new, model-augmented methodology, were 2.61 and 3.41 mWE, respectively. The 2006 and 2007 summer balances were -4.20 and -3.63 mWE, respectively, and the 2006 and 2007 net balances were -1.59 and -0.22 mWE. PDF version of a presentation on the mass balance of South Cascade <span class="hlt">Glacier</span> in Washington state. Presented at the American Geophysical Union Fall Meeting 2010.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C21B0736R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C21B0736R"><span>A new <span class="hlt">glacier</span> inventory for the Karakoram-Pamir region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rastner, P.; Paul, F.; Bolch, T.; Moelg, N.</p> <p>2015-12-01</p> <p>High-quality <span class="hlt">glacier</span> inventories are required as a reference dataset to determine <span class="hlt">glacier</span> changes and model their reaction to climate change, among others. In particular in High Mountain Asia such an inventory was missing for several heavily <span class="hlt">glacierized</span> regions with reportedly strongly changing <span class="hlt">glaciers</span>. As a contribution to GLIMS and the Randolph <span class="hlt">Glacier</span> Inventory (RGI) we have mapped all <span class="hlt">glaciers</span> in the Karakoram and Pamir region within the framework of ESAs <span class="hlt">Glaciers</span>_cci project. <span class="hlt">Glacier</span> mapping was performed using the band ratio method (TM3/TM5) and manual editing of Landsat TM/ETM+ imagery acquired around the year 2000. The mapping was challenged by frequent seasonal snow at high elevations, debris-covered <span class="hlt">glacier</span> tongues, and several surging <span class="hlt">glaciers</span>. We addressed the snow issue by utilizing multi-temporal imagery and improved manual mapping of debris-covered <span class="hlt">glacier</span> tongues with ALOS PALSAR coherence images. Slow disintegration of <span class="hlt">glacier</span> tongues after a surge (leaving still-connected dead ice) results in a difficult identification of the terminus and assignment of entities. Drainage divides were derived from the ASTER GDEM II and manually corrected to calculate topographic parameters. All <span class="hlt">glaciers</span> larger 0.02 km2 cover an area of about 21,700 km2 in the Karakoram and about 11,800 km² in the Pamir region. Most <span class="hlt">glaciers</span> are in the 0.1-0.5 km2 size class for Pamir, whereas for the Karakoram they are in the class <0.1 km2. <span class="hlt">Glaciers</span> between 1 and 5 km2 contribute more than 30% to the total area in Pamir, whereas for the Karakoram region it is only 17%. The mean <span class="hlt">glacier</span> elevation in the Karakoram (Pamir) region is 5426 (4874) m. A comparison with other recently published inventories reveals differences in the interpretation of <span class="hlt">glacier</span> extents (mainly in the accumulation region) that would lead to large area changes if unconsidered for change assessment across different inventories.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/pp/0387b/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/pp/0387b/report.pdf"><span>Recent Activity of <span class="hlt">Glaciers</span> of Mount Rainier, Washington</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sigafoos, Robert S.; Hendricks, E.L.</p> <p>1972-01-01</p> <p>Knowing the ages of trees growing on recent moraines at Mount Rainier, Wash., permits the moraines to be dated. Moraines which are ridges of boulders, gravel, sand, and dust deposited at the margins of a <span class="hlt">glacier</span>, mark former limits of a receding <span class="hlt">glacier</span>. Knowing past glacial activity aids our understanding of past climatic variations. The report documents the ages of moraines deposited by eight <span class="hlt">glaciers</span>. Aerial photographs and planimetric maps show areas where detailed field studies were made below seven <span class="hlt">glaciers</span>. Moraines, past ice positions, and sample areas are plotted on the photographs and maps, along with trails, roads, streams, and landforms, to permit critical areas to be identified in the future. Ground photographs are included so that sample sites and easily accessible moraines can be found along trails. Tables present data about trees sampled in areas near the <span class="hlt">glaciers</span> of Mount Rainier, Wash. The data in the tables show there are modern moraines of different age around the mountain; some valleys contain only one modern moraiine; others contain as many as nine. The evidence indicates a sequence of modern glacial advances terminating at about the following A.D. dates: 1525, 1550, 1625-60, 1715, 1730-65, 1820-60, 1875, and 1910. Nisqually River valley near Nisqually <span class="hlt">Glacier</span> contains one moraine formed before A.D. 1842; Tahoma Creek valley near South Tahoma <span class="hlt">Glacier</span> contains three moraines formed before A.D. 1528; 1843, and 1864; South Puyallup River valley near Tahoma <span class="hlt">Glacier</span>, six moraines A.D. 1544, 1761, 1841, 1851, 1863, 1898; Puyallup <span class="hlt">Glacier</span>, one moraine, A.D. 1846; Carbon <span class="hlt">Glacier</span>, four moraines, 1519, 1763, 1847, 1876; Winthrop <span class="hlt">Glacier</span>, four moraines, 1655, 1716, 1760, amid 1822; Emmons <span class="hlt">Glacier</span>, nine moraines, 1596, 1613, 1661, 1738, 1825, 1850, 1865, 1870, 1901; and Ohanapecosh <span class="hlt">Glacier</span>, three moraines, 1741, 1846, and 1878. Abandoned melt-water and flood channels were identified within moraine complexes below three <span class="hlt">glaciers</span>, and their time of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGC21E..04L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGC21E..04L"><span>Evaluating the Impact of <span class="hlt">Glacier</span> Shrinkage on Water Supply at Volcán Chimborazo, Ecuador</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>La Frenierre, J.; Mark, B. G.</p> <p>2013-12-01</p> <p> becoming less predictable. In the Rio Mocha watershed (the most highly-<span class="hlt">glacierized</span> of Chimborazo's catchments), <span class="hlt">glacier</span> meltwater currently contributes ~10-20% of Rio Mocha discharge at the intake of the Las Abras canal, the region's most important irrigation system. Discussions with system users and direct flow measurements indicate that the canal is now frequently unable to meet irrigation demand during the dry season. Already, the majority of <span class="hlt">non</span>-irrigators in the Chimborazo region now pursue <span class="hlt">non</span>-agricultural livelihood activities for at least part of the year, which often requires either temporary or permanent emigration from local communities to other areas inside and outside of Ecuador. With increasingly unreliable water supply, some farmers with irrigation rights are now being forced to do the same. Should the hydrologic response of the Rio Mocha to continued <span class="hlt">glacier</span> shrinkage mimic that noted in other Andean watersheds, further reduction of water supply during dry periods and increased livelihood vulnerability on the part of local irrigators can be expected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.C11A0480F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.C11A0480F"><span>Seismic Monitoring of Ice Generated Events at the Bering <span class="hlt">Glacier</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fitzgerald, K.; Richardson, J.; Pennington, W.</p> <p>2008-12-01</p> <p>The Bering <span class="hlt">Glacier</span>, located in southeast Alaska, is the largest <span class="hlt">glacier</span> in North America with a surface area of approximately 5,175 square kilometers. It extends from its source in the Bagley Icefield to its terminus in tidal Vitus Lake, which drains into the Gulf of Alaska. It is known that the <span class="hlt">glacier</span> progresses downhill through the mechanisms of plastic crystal deformation and basal sliding. However, the basal processes which take place tens to hundreds of meters below the surface are not well understood, except through the study of sub- glacial landforms and passive seismology. Additionally, the sub-glacial processes enabling the surges, which occur approximately every two decades, are poorly understood. Two summer field campaigns in 2007 and 2008 were designed to investigate this process near the terminus of the <span class="hlt">glacier</span>. During the summer of 2007, a field experiment at the Bering <span class="hlt">Glacier</span> was conducted using a sparse array of L-22 short period sensors to monitor ice-related events. The array was in place for slightly over a week in August and consisted of five stations centered about the final turn of the <span class="hlt">glacier</span> west of the Grindle Hills. Many events were observed, but due to the large distance between stations and the highly attenuating surface ice, few events were large enough to be recorded on sufficient stations to be accurately located and described. During August 2008, six stations were deployed for a similar length of time, but with a closer spacing. With this improved array, events were located and described more accurately, leading to additional conclusions about the surface, interior, and sub-glacial ice processes producing seismic signals. While the <span class="hlt">glacier</span> was not surging during the experiment, this study may provide information on the <span class="hlt">non</span>-surging, sub-glacial base level activity. It is generally expected that another surge will take place within a few years, and baseline studies such as this may assist in understanding the nature of surges.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.C23C0669E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.C23C0669E"><span>Satellite Observations of <span class="hlt">Glacier</span> Surface Velocities in Southeast Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Elliott, J.; Melkonian, A. K.; Pritchard, M. E.</p> <p>2012-12-01</p> <p><span class="hlt">Glaciers</span> in southeast Alaska are undergoing rapid changes and are significant contributors to sea level rise. A key to understanding the ice dynamics is knowledge of the surface velocities, which can be used with ice thickness measurements to derive mass flux rates. For many <span class="hlt">glaciers</span> in Alaska, surface velocity estimates either do not exist or are based on data that are at least a decade old. Here we present updated maps of <span class="hlt">glacier</span> surface velocities in southeast Alaska produced through a pixel tracking technique using synthetic aperture radar data and high-resolution optical imagery. For <span class="hlt">glaciers</span> with previous velocity estimates, we will compare the results and discuss possible implications for ice dynamics. We focus on <span class="hlt">Glacier</span> Bay and the Stikine Icefield, which contain a number of fast-flowing tidewater <span class="hlt">glaciers</span> including LeConte, Johns Hopkins, and La Perouse. For the Johns Hopkins, we will also examine the influence a massive landslide in June 2012 had on flow dynamics. Our velocity maps show that within <span class="hlt">Glacier</span> Bay, the highest surface velocities occur on the tidewater <span class="hlt">glaciers</span>. La Perouse, the only <span class="hlt">Glacier</span> Bay <span class="hlt">glacier</span> to calve directly into the Pacific Ocean, has maximum velocities of 3.5 - 4 m/day. Johns Hopkins <span class="hlt">Glacier</span> shows 4 m/day velocities at both its terminus and in its upper reaches, with lower velocities of ~1-3 m/day in between those two regions. Further north, the Margerie <span class="hlt">Glacier</span> has a maximum velocity of ~ 4.5 m/day in its upper reaches and a velocity of ~ 2 m/day at its terminus. Along the Grand Pacific terminus, the western terminus fed by the Ferris <span class="hlt">Glacier</span> displays velocities of about 1 m/day while the eastern terminus has lower velocities of < 0.5 m/day. The lake terminating <span class="hlt">glaciers</span> along the Pacific coast have overall lower surface velocities, but they display complex flow patterns. The Alsek <span class="hlt">Glacier</span> displays maximum velocities of 2.5 m/day above where it divides into two branches. Velocities at the terminus of the northern branch reach 1</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C23A1206Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C23A1206Y"><span>Predicting critical thresholds in outlet <span class="hlt">glacier</span> terminus behavior, Disko and Uummannaq Bays, West Greenland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>York, A.; Frey, K. E.; Das, S. B.</p> <p>2017-12-01</p> <p>The seasonal and interannual variability in outlet <span class="hlt">glacier</span> terminus position is an important indicator of overall <span class="hlt">glacier</span> health and the net effects of ice-ocean-atmosphere interactions. However, challenges arise in determining a primary driver of <span class="hlt">glacier</span> change, as the magnitude of retreat observed at the terminus is controlled not only by atmospheric and oceanic temperatures, but also physical constraints unique to each <span class="hlt">glacier</span> (e.g., ice mélange buttressing and underlying bedrock/bathymetry) which often lead to a <span class="hlt">non</span>-linear response to climate. For example, previous studies have shown varying magnitudes of terminus retreat over the last 40 years at <span class="hlt">glaciers</span> in West Greenland, despite exposure to similar atmospheric forcings. Satellite imagery can provide the necessary spatially- and temporally-extensive resource for monitoring <span class="hlt">glacier</span> terminus behavior. Here, we constructed a time series of 18 <span class="hlt">glacier</span> termini digitized from over 1200 all-season Landsat images between 1985 and 2015 within Disko and Uummannaq Bays, West Greenland. We calculated change points in the annual maximum terminus retreat of the <span class="hlt">glaciers</span> using a bootstrapping algorithm within a change point detection software. We interpolated the average monthly retreat of each terminus in order to calculate the average seasonal amplitude of each year. We found the 11 <span class="hlt">glaciers</span> in Uummannaq Bay retreated an average of -1.26 ± 1.36 km, while the seven <span class="hlt">glaciers</span> in Disko Bay averaged -1.13 ± 0.82 km. The majority of <span class="hlt">glaciers</span> retreated, yet we see no latitudinal trend in magnitude of retreat on either a seasonal or long-term scale. We observe change points in the annual maximum retreat of four <span class="hlt">glacier</span> termini in Uummannaq Bay and one in Disko Bay which are generally coincident with increased summer sea surface temperatures. In some cases, we observed smaller interannual variability in the average seasonal amplitude of years leading up to a critical threshold, followed by an increase in seasonal variability</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.C31A0276V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.C31A0276V"><span>Analysis of Snow Line and Albedo Conditions By Means of Time-Lapse Photography on Tapado <span class="hlt">Glacier</span>, Chile</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vivero, S.; MacDonell, S.; McPhee, J. P.</p> <p>2014-12-01</p> <p>In the semiarid Coquimbo Region of Chile, high-altitude <span class="hlt">glaciers</span> and seasonal snow are important sources of freshwater for irrigated agriculture and urban consumption. Due to the aridity of the environment, losses due to sublimation are large which means that accurate melt modelling is essential in order to reliably estimate streamflow. Since 2008, the CEAZA glaciology group has been studying the energy and mass balance of the largest <span class="hlt">glacier</span> in the catchment, the Tapado <span class="hlt">Glacier</span> using field and remote sensing measurements, and numerical modelling. The Tapado <span class="hlt">glacier</span> system (30°08' S, 69°55' W) is a complex assemblage of uncovered and debris-covered ice located at the head of the Elqui <span class="hlt">basin</span> between 4500 and 5536 m a.s.l. Energy balance modelling studies at the site have been limited in scope due to the development of ice pinnacles or penitentes on snow and ice surfaces. These features complicate energy distribution across the surface, due to modifications of parameters such as albedo. In this paper, we use time-lapse photography and automatic weather station (AWS) measurements to investigate how the development of penitentes impacts the spatial and temporal variability of albedo across the <span class="hlt">glacier</span> surface and whether terrestrial photography is appropriate for use at such locations. Oblique photographs obtained from a high vantage point were georeferenced using a high resolution digital elevation model available for the entire <span class="hlt">glacier</span> and its environs. By comparing the photographic data with point albedo measurements made at an AWS, distributed albedo maps were produced. Preliminary results suggest that distributed albedo values may be underestimated by the formation and development of penitentes during the ablation season. Moreover, it was observed that the evolution of the snow line during summer was not only topographically controlled but also modified by occasional convective snowfalls. Time-lapse photography provided to be a cost-effective tool for monitoring</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C11A0888M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C11A0888M"><span>Characterization of meltwater 'ingredients' at the Haig <span class="hlt">Glacier</span>, Canadian Rockies: the importance of <span class="hlt">glaciers</span> to regional water resources</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miller, K.; Marshall, S.</p> <p>2017-12-01</p> <p>With rising temperatures, Alberta's <span class="hlt">glaciers</span> are under stresses which change and alter the timing, amount, and composition of meltwater contributions to rivers that flow from the Rocky Mountains. Meltwater can be stored within a <span class="hlt">glacier</span> or it can drain through the groundwater system, reducing and delaying meltwater delivery to <span class="hlt">glacier</span>-fed streams. This study tests whether the <span class="hlt">glacier</span> meltwater is chemically distinct from rain or snow melt, and thus whether meltwater contributions to higher-order streams that flow from the mountains can be determined through stream chemistry. Rivers like the Bow, North Saskatchewan, and Athabasca are vital waterways for much of Alberta's population. Assessing the extent of <span class="hlt">glacier</span> meltwater is vital to future water resource planning. <span class="hlt">Glacier</span> snow/ice and meltwater stream samples were collected during the 2017 summer melt season (May- September) and analyzed for isotope and ion chemistry. The results are being used to model water chemistry evolution in the melt stream through the summer season. A chemical mixing model will be constructed to determine the fractional contributions to the Haig meltwater stream from precipitation, surface melt, and subglacial meltwaters. Distinct chemical water signatures have not been used to partition water sources and understand <span class="hlt">glacier</span> contributions to rivers in the Rockies. The goal of this work is to use chemical signatures of glacial meltwater to help assess the extent of <span class="hlt">glacier</span> meltwater in Alberta rivers and how this varies through the summer season.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001488.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001488.html"><span><span class="hlt">Glaciers</span> and Sea Level Rise</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-08</p> <p>Small valley <span class="hlt">glacier</span> exiting the Devon Island Ice Cap in Canada. To learn about the contributions of <span class="hlt">glaciers</span> to sea level rise, visit: www.nasa.gov/topics/earth/features/<span class="hlt">glacier</span>-sea-rise.html Credit: Alex Gardner, Clark University NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/5537012-hydrocarbon-provinces-productive-trends-libya-adjacent-areas','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5537012-hydrocarbon-provinces-productive-trends-libya-adjacent-areas"><span>Hydrocarbon provinces and productive trends in Libya and <span class="hlt">adjacent</span> areas</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Missallati, A.A.</p> <p>1988-08-01</p> <p>According to the age of major reservoirs, hydrocarbon occurrences in Libya and <span class="hlt">adjacent</span> areas can be grouped into six major systems which, according to their geographic locations, can be classified into two major hydrocarbon provinces: (1) Sirte-Pelagian <span class="hlt">basins</span> province, with major reservoirs ranging from middle-late Mesozoic to early Tertiary, and (2) Murzog-Ghadames <span class="hlt">basins</span> province, with major reservoirs ranging from early Paleozoic to early Mesozoic. In the Sirte-Pelagian <span class="hlt">basins</span> province, hydrocarbons have been trapped in structural highs or in stratigraphic wedge-out against structural highs and in carbonate buildups. Here, hydrocarbon generation is characterized by the combined effect of abundant structural reliefmore » and reservoir development in the same hydrocarbon systems of the same age, providing an excellent example of hydrocarbon traps in sedimentary <span class="hlt">basins</span> that have undergone extensive tensional fracturing in a shallow marine environment. In the Murzog-Ghadames <span class="hlt">basins</span> province, hydrocarbons have been trapped mainly in structural highs controlled by paleostructural trends as basement arches which acted as focal points for oil migration and accumulation.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/pp/1746/','USGSPUBS'); return false;" href="https://pubs.usgs.gov/pp/1746/"><span>Geographic Names of Iceland's <span class="hlt">Glaciers</span>: Historic and Modern</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sigurðsson, Oddur; Williams, Richard S.</p> <p>2008-01-01</p> <p>Climatic changes and resulting <span class="hlt">glacier</span> fluctuations alter landscapes. In the past, such changes were noted by local residents who often documented them in historic annals; eventually, <span class="hlt">glacier</span> variations were recorded on maps and scientific reports. In Iceland, 10 <span class="hlt">glacier</span> place-names are to be found in Icelandic sagas, and one of Iceland's ice caps, Snaefellsjokull, appeared on maps of Iceland published in the 16th century. In the late 17th century, the first description of eight of Iceland's <span class="hlt">glaciers</span> was written. Therefore, Iceland distinguishes itself in having a more than 300-year history of observations by Icelanders on its <span class="hlt">glaciers</span>. A long-term collaboration between Oddur Sigurdsson and Richard S. Williams, Jr., led to the authorship of three books on the <span class="hlt">glaciers</span> of Iceland. Much effort has been devoted to documenting historical <span class="hlt">glacier</span> research and related nomenclature and to physical descriptions of Icelandic <span class="hlt">glaciers</span> by Icelanders and other scientists from as far back as the Saga Age to recent (2008) times. The first book, Icelandic Ice Mountains, was published by the Icelandic Literary Society in 2004 in cooperation with the Icelandic Glaciological Society and the International Glaciological Society. Icelandic Ice Mountains was a <span class="hlt">glacier</span> treatise written by Sveinn Palsson in 1795 and is the first English translation of this important scientific document. Icelandic Ice Mountains includes a Preface, including a summary of the history and facsimiles of page(s) from the original manuscript, a handwritten copy, and an 1815 manuscript (without maps and drawings) by Sveinn Palsson on the same subject which he wrote for Rev. Ebenezer Henderson; an Editor's Introduction; 82 figures, including facsimiles of Sveinn Palsson's original maps and perspective drawings, maps, and photographs to illustrate the text; a comprehensive Index of Geographic Place-Names and Other Names in the treatise; References, and 415 Endnotes. Professional Paper 1746 (this book) is the second</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMGC31F..05T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMGC31F..05T"><span>Effects of Forecasted Climate Change on Stream Temperatures in the Nooksack River <span class="hlt">Basin</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Truitt, S. E.; Mitchell, R. J.; Yearsley, J. R.; Grah, O. J.</p> <p>2017-12-01</p> <p>The Nooksack River in northwest Washington State provides valuable habitat for endangered salmon species, as such it is critical to understand how stream temperatures will be affected by forecasted climate change. The Middle and North Forks <span class="hlt">basins</span> of the Nooksack are high-relief and glaciated, whereas the South Fork is a lower relief rain and snow dominated <span class="hlt">basin</span>. Due to a moderate Pacific maritime climate, snowpack in the <span class="hlt">basins</span> is sensitive to temperature increases. Previous modeling studies in the upper Nooksack <span class="hlt">basins</span> indicate a reduction in snowpack and spring runoff, and a recession of <span class="hlt">glaciers</span> into the 21st century. How stream temperatures will respond to these changes is unknown. We use the Distributed Hydrology Soil Vegetation Model (DHSVM) coupled with a <span class="hlt">glacier</span> dynamics model and the River <span class="hlt">Basin</span> Model (RBM) to simulate hydrology and stream temperature from present to the year 2100. We calibrate the DHSVM and RBM to the three forks in the upper 1550 km2 of the Nooksack <span class="hlt">basin</span>, which contain an estimated 3400 hectares of glacial ice. We employ observed stream-temperature data collected over the past decade and hydrologic data from the four USGS streamflow monitoring sites within the <span class="hlt">basin</span> and observed gridded climate data developed by Linveh et al. (2013). Field work was conducted in the summer of 2016 to determine stream morphology, discharge, and stream temperatures at a number of stream segments for the RBM calibration. We simulate forecast climate change impacts, using gridded daily downscaled data from global climate models of the CMIP5 with RCP4.5 and RCP8.5 forcing scenarios developed using the multivariate adaptive constructed analogs method (MACA; Abatzoglou and Brown, 2011). Simulation results project a trending increase in stream temperature as a result of lower snowmelt and higher air temperatures into the 21st century, especially in the lower relief, unglaciated South Fork <span class="hlt">basin</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <div class="footer-extlink text-muted" style="margin-bottom:1rem; text-align:center;">Some links on this page may take you to non-federal websites. 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