This interactive Flash exercise and animation explores glaciers, including their formation, growth, and retreat. This resource provides animations, diagrams, models in which students can see the influence of temperature and precipitation on glacier growth, and supplementary information that may serve as an overview or review of glaciers for introductory level physical geology or Earth science students at the high school or undergraduate level.
This is a great site to help you learn about glaciers! On this webpage, you will learn what glaciers are, how they are formed, the different types of glaciers, their anatomy, how they move, and about glacial erosion. This site also has a model that helps you to understand glacial growth and retreat.
Song, Yu; Zhu, Tong; Cai, Xuhui; Lin, Weili; Kang, Ling
Persistent glacier winds blowing from noon to midnight in summer are present in the Rongbuk Valley, north of Mount Everest, with a maximum speed of 10 m s-1 and a vertical thickness as high as 1 km. These glacier winds may bring upper level atmosphere ozone to the surface, having a significant impact on the atmospheric environment. Such phenomena may be typical of the Tibetan Plateau, where most high mountains are covered by snow or glacier ice throughout the year. The Advanced Regional Prediction Model was used to simulate the down-valley flows, using realistic topography but neglecting synoptic winds. The modeling results agree well with the observations obtained in June 2002, revealing that the glacier winds are thermal flows primarily driven by the along-valley temperature gradient between the colder air over the glacier surface and the warmer air over surface areas covered by rock debris, which maintains air advection along the Rongbuk Valley. Downslope winds over the glacier slopes, especially from the western valley side, and the West Rongbuk Glacier, were forced by their inertia farther down into the valley and would intensify the glacier winds. The narrowing of the Rongbuk Valley could also speed up the glacier winds. Sensitivity tests showed that the detailed distribution of the Rongbuk Glacier, delineated by data from the Enhanced Thematic Mapper Plus on Landsat 7, plays an important role in glacier winds development. The glacier winds could be much weaker in winter when the area is completely snow covered.
Hambrey, Michael; Alean, Jürg
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.
Glaciers are found on every continent except Australia. This interactive feature provides an introduction to these moving streams of ice, which cover about 10 percent of Earth's land surface and hold between two and three percent of its water. Topics include what glaciers are, where and why they form, what influences their growth and decline, and how an apparently solid mass appears to flow like a river. There is also a brief description of some types of glaciers. A background essay and discussion questions are included.
Maloof, A.; Fang, B.; Tootle, G. A.; Lakshmi, V.; Kerr, G.
The Wind River Range (WRR) is a continuous mountain range approximately 160 km in length in west-central Wyoming, USA. The Wind River Range is host to roughly 680 snow and ice bodies with 63 of these considered glaciers including seven of the ten largest glaciers in the American Rocky Mountains. The presence of glaciers results in meltwater contributions to streamflow during the late summer (July, August, and September - JAS) when snowmelt is decreasing, temperatures are high, precipitation is low, and irrigation demand peaks. Most studies indicate that the glaciers in the Wind River Range have been retreating since the 1850's, the approximate end of the Little Ice Age. Thus, the quantification of glacier meltwater (e.g., volume, mass) contributions to late-summer/early-fall streamflow is important given this resource is dwindling due to glacier recession. In this study, we selected glaciers in the WRR and obtained satellite products of study region. The ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) Level 1B imageries which are at 15 m spatial resolution between 2006~2012 were classified using supervised method and the glacier boundaries were extracted for tracking their changes. By combining ASTER L1B imageries of different years with two remote sensing derived DEM (Digital Elevation Model) datasets: ASTER GDEM (ASTER Global Digital Elevation), which is at 30 m spatial resolution and acquired prior to 2006 and Global Multi-resolution Terrain Elevation Data (GMTED 2010) which is at 250 m, 500 m and 1 km, and acquired in 2010, the 3D-view glacier volumetric loss extent could also be mapped and quantified. Assessing glacier area and volume variability is very important for evaluating and predicting glacier change in response to a changing environment.
Thompson, D.; Bell, J. E.; Edmunds, J.; Tootle, G. A.; Kerr, G.
The Wind River Range (WRR) in west central Wyoming is host to 63 glaciers, while the Teton Range (TR) is host to 10 named glaciers. These glaciers serve as natural water reservoirs, and the continued recession of glaciers will impact agricultural water supply in the region. Glacier area changes in the WRR were estimated for 44 glaciers using un-rectified high resolution (1 m) aerial photography from 1966 to 2006. Additionally, glacier area was also developed for ten of the 44 glaciers using resampled aerial photography at 10 m (SPOT), 15 m (ASTER), 22.5 m (IRS-LISS) and 30 m (Landsat) resolutions for 1966 and 2006. The total surface area of the 44 glaciers was calculated to be 45.9 ± 0.13 km2 in 1966 and 28.5 ± 0.11 km2 in 2006, an average decrease of 38% over the 40 year period. Small glaciers experienced noticeably more area reduction than large glaciers. Of the 44 glaciers analyzed, 22 had an area of greater than 0.5 km2 in 1966, while 22 were less than 0.5 km2 in 1966. The glaciers with a surface area less than 0.5 km2 experienced an average surface area loss (fraction of 1966 surface area) of 47%, while the larger glaciers (greater than 0.5 km2) experienced an average surface area loss of 36% in 2006. Of the ten glaciers analyzed by resampling, the total surface area (fraction of 1966 surface area) decreased by 36.8% using aerial photographs, 36.5% using SPOT images, 36.6% using ASTER images, 36.0% using IRS-LISS images and 37.1% using Landsat images. Glacier area changes in the TR were estimated for three glaciers using un-rectified aerial photography from 1967 to 2006. The total surface area of the three glaciers was calculated to be 0.53 ± 0.13 km2 in 1967 and 0.40 ± 0.10 km2 in 2006, an average decrease of 34% over the 39 year period. The smallest glacier Teepe experienced the most noticeable lost, losing 60% while the Teton glacier lost 17%. Applying area-volume scaling relationships for Teton, Middle Teton, and Teepe glaciers, volume loss was estimated to be 3.2 million cubic meters (MCM) over the 35 year period, which results in an estimated 4 to 10% contribution to warm season (July - September) streamflow. Accompanied with the calculation of glacier area loss, the amount of glacial volume lost was also determined for selected glaciers in the WRR from 1966 to 1989. A subset of 29 glaciers throughout two basins were analyzed as part of a paired watershed (glaciated vs. non-glaciated) analysis. Through the use of photogrammetric techniques, volume loss in the 17 glaciers of the Upper Green River sub-basin was estimated to be 319 x 106 m3 (14% area loss), while 12 glaciers in the Bull Lake sub-basin lost 369 x 106 m3 (16% area loss) over the 23 year period. The pure glacial ice melt contribution to late summer (Jul., Aug. and Sep.) downstream flow was 8% and 14%, respectively, for the basins above. Also, the paired watershed analysis indicated glaciers delayed spring snowmelt runoff to an extent where, in combination with glacial ice melt, the flow resulting from the glacial terminus was approximated as 40% of the late summer downstream flows.
Tootle, G. A.; Marks, J.; Kerr, G.
The Wind River Range (WRR) of Wyoming is host to approximately 63 glaciers. Extensive research has been conducted using remote imagery to estimate the area changes of these glaciers, with the goal of estimating the potential impacts of these changes on watershed streamflow. Results show that the glaciers were mostly in recession from 1966 to 2006 with glacier area losses estimated at 38%. Recent research efforts (paired watershed analysis), which supplement the results from the remote imagery analyses, evaluated late summer [July-August-September (JAS)] streamflows from glaciated and non-glaciated watersheds. The difference in observed JAS flows between glaciated and non-glaciated watersheds ranged between 8% and 23% and glaciers accounted for 23% to 54% of the observed late summer (JAS) flow in glaciated watersheds. This was primarily attributed to the glaciers decelerating the snowmelt runoff through internal storage/delayed release of liquid water and, to a lesser extent, the loss of glacier mass. However, no estimates were made as to what percentage of late summer streamflow is attributed to glacier mass (volume) loss. Applying established empirical relationships between glacier area and volume, estimates of glacier volume loss and the contribution to late summer streamflow were estimated for two glaciated watersheds of the WRR, the Upper Green River basin (west slope) and Bull Lake Creek basin (east slope). The results show that glacier mass contributes 2% to 8% of late summer streamflow resulting in estimated glacier losses of 0.4 to 0.7 meters per year from 1966 to 2006.
In this online activity, learners adjust mountain snowfall and temperature to see how glaciers grow and shrink. They will use scientific tools to measure thickness, velocity and glacial budget. This activity includes an online simulation, sample learning goals, teaching ideas, and translations in over 20 languages.
DeVisser, Mark H.; Fountain, Andrew G.
The Wind River Range spans roughly 200 km along the continental divide in western Wyoming and encompasses at least 269 glaciers and perennial snowfields totaling 34.34 ± 0.13 km2 (2006), including Gannett Glacier, the largest glacier (2.81 km2) in the continental U.S. outside of Washington State. To track changing glacier and perennial snow surface area over the past century we used historic maps, aerial photography, and geologic evidence evident in said imagery. Since the end of the Little Ice Age (~ 1900), when the glaciers retreated from their moraines, to 2006 the ice-covered area shrank by ~ 47%. The main driver of surface area change was air temperature, with glaciers at lower elevations shrinking faster than those at higher elevations. The total contribution of ice wastage to late summer stream flow ranged from 0.4 to 1.5%, 0.9 to 2.8%, 1.7 to 5.4%, and 3.4 to 10.9% in four different watersheds, none of which exceeded 7% glacier cover. Results from previous studies were difficult to include because of differences in interpretation of glacier boundaries, because of poor imagery, or to extensive seasonal snow. These difficulties highlight potential problems in combining data sets from different studies and underscores the importance of reexamining past observations to ensure consistent interpretation.
Thompson, Derrick R.
Spatial changes in glacier area for 44 glaciers in Wyoming's Wind River Range were estimated through a comparison of historic aerial photography from 1966 to 2006. The total surface area of the 44 glaciers was estimated to be 45.9 +/- 1.6 km2 in 1966 and 28.5 +/- 0.4 km 2 in 2006, a decrease of 42%. Volumes of individual glaciers during the 41-year period were estimated utilizing the Bahr et al. (1997) volume-area scaling technique. The total ice volume lost was estimated to be 0.89 +/- 0.4 km3, which equates to 4.2% and 9.7% of warm season (July-September) streamflow for the Green River and Bull Lake Creek watersheds for the 41-year period. It was also determined that the Dinwoody Creek watershed contributed 12.4% to warm season (July-September) streamflow during the 1989 to 2006 period. Glacial surface area was also estimated utilizing resampled aerial photography to assess the relationship between area and measurement scale. Aerial photographs were resampled to resolutions of 10 meter, 15 meter, 22.5 meter and 30 meter to represent other satellite image resolutions used for evaluating glacier boundaries. The results show a linear decrease of total glacier area as resolution decreases. When comparing 1 meter resolution to the 30 meter resolution photographs for 1966 and 2006 photos, an average decrease total glacier area of 5% was calculated. It was concluded that high-resolution aerial photography remains the preferred and most accurate source for measuring glacier characteristics.
Cai, Xuhui; Song, Yu; Zhu, Tong; Lin, Weili; Kang, Ling
High ozone concentrations, combined with low humidity and strong, persistent glacier winds, were found at the surface of Rongbuk Valley, north of Mount Everest, with sharply increased ozone concentrations in their vertical profiles. Glacier winds and their roles in vertical exchange of the atmosphere were investigated numerically to understand the phenomena. A Lagrangian particle dispersion model was used to carry out numerical experiments (forward-in-time simulations) and footprint analysis (backward-in-time simulations). The meteorological data inputs for these experiments were derived from the Advanced Regional Prediction System. Results showed that glacier winds may lead to significant downward transport of 1.5-2 km during the daytime from the northern slopes of Mount Everest. Glacier winds could advance down through the valley, with strong upward motions shown as a rolling up in front of their leading edge. Combining with upslope winds at two sidewalls of the valley or up-valley winds of tributaries, the lifting flows produced strong mixing of the atmosphere to a depth of approximately 3 km. Three-dimensional footprints derived from the particle dispersion model for the observational site, Rongbuk Monastery, clearly show influence from the mountainside of Mount Everest and from the southern part of the valley. The vertical extension of influence was as much as 2-3 km. Good correlation was found between the influence height and the ozone concentration. All the simulation results strongly indicate that the glacier winds and their related vertical exchange processes "pump down" ozone-rich air from upper levels to the surface of the valley.
Litt, Maxime; Sicart, Jean-Emmanuel; Helgason, Warren D.; Wagnon, Patrick
We investigate properties of the turbulent flow and sensible heat fluxes in the atmospheric surface layer of the high elevation tropical Zongo glacier ( m a.s.l., S, Bolivia) from data collected in the dry season from July to August 2007, with an eddy-covariance system and a 6-m mast for wind speed and temperature profiles. Focus is on the predominant downslope wind regime. A low-level wind-speed maximum, around a height of m, is detected in low wind conditions (37 % of the time). In strong wind conditions (39 % of the time), no wind-speed maximum is detected. Statistical and spectral analyses reveal low frequency oscillations of the horizontal wind speed that increase vertical mixing. In strong winds, wavelet analysis shows that coherent structures systematically enhance the turbulent sensible heat fluxes, accounting for 44-52 % of the flux. In contrast, in low wind conditions, the katabatic flow is perturbed by its slow oscillations or meandering motions, inducing erratic turbulent sensible heat fluxes. These motions account for 37-43 % of the flux. On tropical glaciers, the commonly used bulk aerodynamic profile method underestimates the eddy-covariance-based flux, probably because it does not account for low frequency disturbances that influence the surface flow in both wind regimes.
A project to learn about ice cores and Antarctica. Use handout lab (Webquest: Glaciers) and follow instructions given for each procedure. Go to Ice Core Changes Go to Glacial Loss Go to Glacial Cover Animation Go to Snow Cover Go to Gulkana Glacier Home Page Go to Glacial Topography Go to Glacial Picture Archive Go to Additional Glacier Pictures ...
Kaser, Georg; Osmaston, Henry
Tropical glaciers are both highly sensitive indicators of global climate and fresh water reservoirs in some fast developing regions. This book gives a theoretical and practical analysis of tropical glaciology including a useful definition of tropical glacier-climate regimes and an analysis of the main glaciological variables. The Rwenzori and the Cordillera Blanca are investigated as examples of tropical glacierized mountains. The fluctuations of their glaciers since the end of the Little Ice Age are reconstructed and the probable climatic reasons are discussed. The evidence of great expansions of mountain glaciers throughout the tropics on several occasions during the Quaternary are summarized, examined and then applied and contrasted.
This video from a 2005 NOVA program features scientists who study how the Jakobshavn Isbrae glacier in western Greenland is shrinking and moving faster due to increased melting over the past ten years. The video includes footage of scientists in the field explaining methods and animation of ice sheet dynamics leading to faster glacier movement.
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The rare western glacier stonefly (Zapada glacier) is native to Glacier National Park and is seeking habitat at higher elevations due to warming stream temperature and glacier loss due to climate warming. ...
The rare western glacier stonefly (Zapada glacier) is native to Glacier National Park and is seeking habitat at higher elevations due to warming stream temperature and glacier loss due to climate warming. ...
Litt, M.; Sicart, J.-E.; Helgason, W.
Over glaciers in the outer tropics, during the dry winter season, turbulent fluxes are an important sink of melt energy due to high sublimation rates, but measurements in stable surface layers, in remote and complex terrains remain challenging. Eddy-covariance (EC) and bulk-aerodynamic (BA) methods were used to estimate surface turbulent heat fluxes of sensible (H) and latent heat (LE) in the ablation zone of the tropical Zongo glacier, Bolivia (16° S, 5080 m a.s.l.), from 22 July to 1 September 2007. We studied the turbulent fluxes and their associated random and systematic measurement errors under the three most frequent wind regimes. For nightly, density-driven katabatic flows, and for strong downslope flows related to large-scale forcing, H generally heats the surface (i.e., is positive), while LE cools it down (i.e., is negative). On average, both fluxes exhibit similar magnitudes and cancel each other out. Most energy losses through turbulence occur for daytime upslope flows, when H is weak due to small temperature gradients and LE is strongly negative due to very dry air. Mean random errors of the BA method (6% on net H + LE fluxes) originated mainly from large uncertainties in roughness lengths. For EC fluxes, mean random errors were due mainly to poor statistical sampling of large-scale outer-layer eddies (12%). The BA method is highly sensitive to the method used to derive surface temperature from long-wave radiation measurements and underestimates fluxes due to vertical flux divergence at low heights and nonstationarity of turbulent flow. The EC method also probably underestimates the fluxes, but to a lesser extent, due to underestimation of vertical wind speed and to vertical flux divergence. For both methods, when H and LE compensate each other in downslope fluxes, biases tend to cancel each other out or remain small. When the net turbulent fluxes (H + LE) are the largest in upslope flows, nonstationarity effects and underestimations of the vertical wind speed do not compensate, and surface temperature errors are important, so that large biases on H + LE are expected when using both the EC and the BA method.
West, Michael E.; Larsen, Christopher F.; Truffer, Martin; O'Neel, Shad; LeBlanc, Laura
We present a framework for interpreting small glacier seismic events based on data collected near the center of Bering Glacier, 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 glacier events and that the hybrid glacier events may be caused by the rush of water into newly opening pathways.
This pair of MISR images of the Pine Island Glacier in western Antarctica was acquired on December 12, 2000 during Terra orbit 5246. At left is a conventional, true-color image from the downward-looking (nadir) camera. The false-color image at right is a composite of red band data taken by the MISR forward 60-degree, nadir, and aftward 60-degree cameras, displayed in red, green, and blue colors, respectively. Color variations in the left (true-color) image highlight spectral differences. In the multi-angle composite, on the other hand, color variations act as a proxy for differences in the angular reflectance properties of the scene. In this representation, clouds show up as light purple. Blue to orange gradations on the surface indicate a transition in ice texture from smooth to rough. For example, the bright orange 'carrot-like' features are rough crevasses on the glacier's tongue. In the conventional nadir view, the blue ice labeled 'rough crevasses' and 'smooth blue ice' exhibit similar coloration, but the multi-angle composite reveals their different textures, with the smoother ice appearing dark purple instead of orange. This could be an indicator of different mechanisms by which this ice is exposed. The multi-angle view also reveals subtle roughness variations on the frozen sea ice between the glacier and the open water in Pine Island Bay.To the left of the 'icebergs' label are chunks of floating ice. Additionally, smaller icebergs embedded in the frozen sea ice are visible below and to the right of the label. These small icebergs are associated with dark streaks. Analysis of the illumination geometry suggests that these streaks are surface features, not shadows. Wind-driven motion and thinning of the sea ice in the vicinity of the icebergs is one possible explanation.Recently, Robert Bindschadler, a glaciologist at the NASA Goddard Space Flight Center discovered in Landsat 7 imagery a newly-formed crack traversing the Pine Island Glacier. This crack is visible as an off-vertical dark line in the MISR nadir view. In the multi-angle composite, the crack and other stress fractures show up very clearly in bright orange. Radar observations of Pine Island Glacier in the 1990's showed the glacier to be shrinking, and the newly discovered crack is expected to eventually lead to the calving of a major iceberg.MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.
This reference guide provides a brief review of glaciers in the Northeastern U.S. It then focuses on the glacial affects in four areas, an inland basin near the Finger Lakes area of New York, the Appalachian/Piedmont through New York and Pennsylvania, the coastal plain and the exotic terrane of New England. Topics covered include glacial scouring, glacial deposits and periglacial features.
The thick, crevassed, ice flows of historic Shepard Glacier have been diminished to less than 0.1 square kilometer in area by 2005. According to the criteria set by the USGS Repeat Photography Project, Shepard Glacier is now considered to be too small to be defined as a glacier. (Blase Reardon)...
View of Columbia Glacier's terminus as it enters the waters of Prince William Sound. Columbia Glacier is one of Alaska's many tidewater glaciers, and it has been the focus of numerous studies due to its unusually high rate of retreat. The glacier has retreated nearly 20 km (12.43 mi) since 1980. In ...
This August 1941 photograph is of Muir Glacier in Glacier Bay National Monument, Alaska. It shows the lower reaches of Muir Glacier, then a large, tidewater calving valley glacier and its tributary, Riggs Glacier. For nearly two centuries before 1941, Muir Glacier had been retreating. In places, a t...
Williams, Richard S., Jr.; Ferrigno, Jane G.
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 supraglacial morainic debris and crevasses. The maps are revised every 6 years by use of aerial photogrammetric methods. The possibility of producing a glacier inventory by combining the topographic maps with Landsat digital and visual data is discussed. ALPS: FRENCH: The glaciers of the French Alps are distributed in four main groups and have a total area of 350 square kilometers. The northernmost group, on the Mont Blanc massif, has a glacier area of 110 square kilometers, which includes Met de Glace, which, with an area of 40 square kilometers, is the largest glacier in the Western Alps. Farther south, the Massif de la Vanoise contains 130 glaciers that have a total area of 85 square kilometers. The glaciers of the Grandes Rousses massif have a total area of 11 square kilometers. Lastly, the Massif du Pelvoux has a total glacier area of 120 square kilometers. Studies of glacier variations since 1600 A.D. have shown numerous fluctuations in glacier length. The glaciers on Mont Blanc that appear to show similar fluctuations in fact have different individual response times. Mass-balance measurements are presently being carried out on nine glaciers. The measurements on one of these glaciers, Glacier de Saint Sorlin, have been used to validate a linear statistical model for mass-balance variation. The model seems to give good results when extended over the entire region of French Alpine glaciers. New methods of mass-balance reconstructions by use of a continuity equation are discussed. Current satellite data have limited usefulness for glacier studies in the French Alps, with the exception of the method correlating changes in the elevation of snowline to changes in glacier mass balance. ALPS: ITALIAN: Research carried out by Italian glaciologists in support of the World Glacier Inventory project identified approximately 1,400 glaciers in the mountain groups of the Italian Alps. The total surface area of all glaciers, glacierets, and permanent snow fields in Italy with
The National Snow and Ice Data Center (NSIDC)
This image collection from the National Snow and Ice Data Center features 14 pairs of Alaskan glacier photographs. Each photographic pair consists of a late-19th or early-20th century photograph and a 21st century photograph taken from the same location. The comparative photographs clearly show substantial changes in glacier position and size and document significant landscape evolution and vegetative succession. The site also provides links to pairs of photographs of glaciers in Switzerland, a repeat photography project at Glacier National Park by the USGS, a glacier database which features satellite images and maps, and further information on glaciers.
Freudiger, Daphné; Stahl, Kerstin; Weiler, Markus
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 area. The derived predictors will be further analyzed and the observed general patterns will be compared to modeling studies of glacier changes.
Meier, Mark; Post, Austin
Most Americans have never seen a glacier, and most would say that glaciers are rare features found only in inaccessible, isolated wilderness mountains. Are they really so rare? Or are they really potentially important sources of water supply?
This interactive slide show presents aerial photographs of seven glaciers worldwide. All of the glaciers present some form of hazard due to the rapid melting of mountain glaciers and a detailed explanation is given for each. Two of the photos contain superimposed before and after photographs and a sliding line which allows the viewer to alternate the two views. Locations of the glaciers include Bhutan and Nepal, Russia and Italy, as well as Alaska in the United States.
This National Snow and Ice Data Center's site contains information for wide range of audiences from glaciologists to grade school students. Data and Science offers links to glacier research, projects, and glaciological organizations online. Another section offers glacier facts, questions and answers, a glossary, a photo gallery, bibliography and links to glacier information on the web. Recent global newsworthy events are chronicled, and a tutorial offering a quick tour through the life of a glacier is available.
In this activity, students compare two photographs (with time spans of 30-100 years between photos) of specific Alaskan glaciers to observe how glaciers have changed over the time interval. Activity is a good kickoff for learning about glaciology - how and why glaciers form, grow and shrink, and their relation to climate change.
J. F. Shroder; M. Bishop; U. Haritashya; J. Olsenholler
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
This "Science Now" feature from the Public Broadcasting Service (PBS) television program "Nova" shows students how remote sensing by satellites can be used to monitor and evaluate hazards presented by glaciers as the climate becomes warmer, causing the glaciers to melt. The feature, which can be presented as a slide show, consists of 11 satellite images with brief written descriptions that explain such hazards as ice collapses and avalanches, flooding by meltwater, and bursting glacier lakes.
This lesson plan provides instruction to teachers for creating a glacier in the classroom to demonstrate how glaciation affects landforms. Learning objectives include student understanding that as glaciers move, they create a variety of patterns on landforms by a process called glacial scraping, that the scraping patterns left by a glacier depend on how the glacier moved over the landform, and that the evidence of glaciation left by glacial scraping provides clues to the climate in a particular place over a long period of time. The site also includes relevant vocabulary words with sound recordings for pronunciation. There are ideas presented for more advanced activities, discussion questions, and additional sources to consult.
The Glaciers Teacher's Guide Web site was created by Arizona educator Patti Greenleaf. The site provides everything needed to complete the online activity, which is geared to students in grades 4 to 5. Objectives of the lesson include having students define what a glacier is, correctly use some terminology related to glaciers, describe how they form and move, and finally be able to tell where glaciers are located today. These objectives are accomplished by having the students read the provided text as well as looking at various photographs and movies. The structure and material of the site are its highlight, both of which are simple but effective.
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
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
Photographer Tad Pfeffer capturing images of Columbia Glacier in Prince William Sound, Alaska. He is looking down-glacier towards the ice front, which faces open water in the fjord. This open water is extremely rare, and has not happened again since 2005. The fjord is typically covered with iceberg ...
Helicopters and satellite phones were integral to the geologic field response. Here, Peter Haeussler is calling a seismologist to pass along the discovery of the Susitna Glacier thrust fault. View is to the north up the Susitna Glacier. The Denali fault trace lies in the background where the two lan...
The world's glaciers are shrinking at alarming rates, and many scientists believe it is due to changes in climate. Dr. Lonnie Thompson of Ohio State University and Dr. Douglas Hardy of UMass-Amherst discuss glaciers and how they melt, and pay special attention to Africa's tallest mountain, Mt. Kilimanjaro. "Changing Planet" is produced in partnership with the National Science Foundation.
This site features links to all aspects of Glacier Peak, a volcano in the Cascade Range, including its geographic setting, and geologic and eruptive history. Glacier Peak is not prominently visible from any major metropolitan centers, and thus its attractions, as well as its hazards, tend to be overlooked. Yet, Glacier Peak has produced larger and more explosive eruptions than any other Washington volcano except Mount St. Helens. Glacier Peak was not known by settlers to be a volcano until the 1850s, when Native Americans mentioned it to naturalist George Gibbs. Not until 1898 did Glacier Peak appear on a published map under its current name. Links labeled 'Special Items of Interest' include information about volcanic highlights and features, and points of interest. Other links lead to maps, graphics, images, publications, reports, and other items of interest involving this volcano and others.
This interactive resource explains what glaciers are, where they are found, how they form, and how they move. The types and parts of glaciers are discussed, as well as ice ages, the different types of landforms that may result from glaciation, and how scientists monitor glaciers. Examples from our national parks are also highlighted as case studies to illustrate how glaciers have created landscapes.
This glossary provides definitions of terms necessary to understand the modern glacier environment. Terms are listed in alphabetical order and are accompanied by photographs. A separate section provides definitions of each type, accompanied by a photograph of an example.
This earth systems field lab begins with an in-class guided inquiry experience which uses Minnesota Geological Survey 3-D maps of the upper Midwest to determine where they believe glaciers may have had an influence. They will determine this by looking at landscapes and compiling their own evidence from the maps. They will also offer evidence for a hypothesis they generate which involves the direction that the glacier was traveling. The two-day lesson ends (after student presentations on their findings about glaciers) with a field investigation of one of our parking lot snow banks. Students will compare and contrast what they know about glaciers, with one of our parking lot snow banks, determining any similarities with how the landscape may have appeared during the Pleistocene.
DeWayne, Cecil L.; Green, J.R.; Vogt, S.; Michel, R.; Cottrell, G.
Meltwater runoff from glaciers can result from various sources, including recent precipitation and melted glacial ice. Determining the origin of the meltwater from glaciers through isotopic analysis can provide information about such things as the character and distribution of ablation on glaciers. A 9.4 m ice core and meltwater were collected in 1995 and 1996 at the glacigenic Galena Creek rock glacier 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 Glacier in the Wind River Range of Wyoming collected in 1991-95. Meltwater samples from three sites on the rock glacier 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 Glacier 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 Glacier. 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 Glacier ice core that was not affected by weapons testing fallout and the ice core collected from the Galena Creek rock glacier. Tritium concentrations from the rock glacier 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 Glacier 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 Glacier deposited in the early 1960s during peak weapons testing fallout for this isotope was 360 TU. One meltwater sample from the rock glacier was analyzed for 35S with a measured concentration of 5.4??1.0 millibecquerel per liter (mBeq/l). Modern precipitation in the Rocky Mountains contains 35S from 10 to 40 mBeq/L. The ??18O results in meltwater from the Galena Creek rock glacier (-17.40??0.1 to -17.98??0.1 per mil) are similar to results for modern precipitation in the Rocky Mountains. Comparison of these isotopic concentrations from the two glaciers suggest that the meltwater at the Galena Creek site is composed mostly of melted snow and rain that percolates through the rock debris that covers the glacier. Additionally, this water from the rock debris is much younger (less than two years) than the reported age of about 2000 years for the subsurface ice at the mid-glacier coring site. Thus the meltwater from the Galena Creek rock glacier is composed primarily of melted surface snow and rain water rather than melted glacier ice, supporting previous estimates of slow ablation rates beneath the surface debris of the rock glacier.
Ayala, A.; Pellicciotti, F.; Shea, J. M.
Air temperature is one of the most relevant input variables for snow and ice melt calculations. However, local meteorological conditions, complex topography, and logistical concerns in glacierized regions make the measuring and modeling of air temperature a difficult task. In this study, we investigate the spatial distribution of 2 m air temperature over mountain glaciers and propose a modification to an existing model to improve its representation. Spatially distributed meteorological data from Haut Glacier d'Arolla (Switzerland), Place (Canada), and Juncal Norte (Chile) Glaciers are used to examine approximate flow line temperatures during their respective ablation seasons. During warm conditions (off-glacier temperatures well above 0°C), observed air temperatures in the upper reaches of Place Glacier and Haut Glacier d'Arolla decrease down glacier along the approximate flow line. At Juncal Norte and Haut Glacier d'Arolla, an increase in air temperature is observed over the glacier tongue. While the temperature behavior over the upper part can be explained by the cooling effect of the glacier surface, the temperature increase over the glacier tongue may be caused by several processes induced by the surrounding warm atmosphere. In order to capture the latter effect, we add an additional term to the Greuell and Böhm (GB) thermodynamic glacier wind model. For high off-glacier temperatures, the modified GB model reduces root-mean-square error up to 32% and provides a new approach for distributing air temperature over mountain glaciers as a function of off-glacier temperatures and approximate glacier flow lines.
USGS scientist shoots a repeat photograph of Grinnell Glacier in Glacier National Park to illustrate glacial recession due to impacts of climate change. *note ? logo on scientists hat is logo from USGS Northern Rocky Mountain Science Center, not private. ...
National Energy Education Development (NEED) Project
This document examine wind power as an energy resource. The reading will define wind and discuss topics such as (1) The history of wind machines, (2) Today's windmills, and (3) Types of wind machines. This resource is structured as an informational handout to supplement your energy activities or to generate discussion questions. Copyright 2005 International Technology Education Association
Heavner, M.; Habermann, M.; Hood, E. W.; Fatland, D. R.
Glaciers along the Gulf of Alaska are thinning and retreating rapidly. An important control on the rate at which ice is being lost is basal motion because higher glacier velocities increase the rate at which ice is delivered to ablation zones. Recent research has focused on understanding the effects of sub-glacial water storage on glacier basal motion. In this study, we examined two seasons of the effect of hydrologic controls (from large rainfall events as well as a glacier lake outburst floods) on the velocity of the Lemon Creek Glacier in southeastern Alaska. Lemon Creek Glacier is a moderately sized (~16~km2) temperate glacier at the margin of the Juneau Icefield. An ice-marginal lake forms at the head of the glacier and catastrophically drains once or twice every melt season. We have instrumented the glacier with two meteorological stations: one at the head of the glacier near the ice-marginal lake and another several kilometers below the terminus. These stations measure temperature, relative humidity, precipitation, incoming solar radiation and wind speed and direction. Lake stage in the ice-marginal lake was monitored with a pressure transducer. In addition, Lemon Creek was instrumented with a water quality sonde at the location of a US Geological Survey gaging station approximately 3 km downstream from the glacier terminus. The sonde provides continuous measurements of water temperature, dissolved oxygen, turbidity and conductivity. Finally, multiple Trimble NetRS dual frequency, differential GPS units were deployed on the glacier along the centerline of the glacier. All of the instruments were run continuously from May-September 2008 and May-September 2009 and captured threee outburst floods associated with the ice-marginal lake drainage as well as several large (>3~cm) rainfall events associated with frontal storms off of the Gulf of Alaska in late summer. Taken together, these data allow us to test the hypothesis that water inputs which overwhelm subglacial drainage networks result in increased rates of basal motion. 2008 was an extremely rainy summer, and the (single) lake drainage occurred during the largest precipitation even of the summer. 2009 on the other hand, was comparatively dry and sunny for the majority of the summer--the first lake drainage occurred during a several day stretch of sunny weather. The lake refilled during an extreme rainfall (20 cm of rain was recorded in a 24 hour period at a met station 16 km away and about 500 m lower in elevation) and then subsequently drained during a rainy period. We focus on the comparison of the data from two years, including the glacial response to the lake drainage with and without accompanying precipitation inputs.
Habermann, M.; Hood, E.; Heavner, M.; Motyka, R.
Glaciers along the Gulf of Alaska are thinning and retreating rapidly and over the last century this loss of ice has contributed measurably to global sea level rise. An important control on the rate at which ice is being lost is basal motion because higher glacier velocities increase the rate at which ice is delivered to ablation zones. Recent research has focused on understanding the effects of sub-glacial water storage on glacier basal motion. In this study, we examined how water inputs from large rainfall events as well as a glacier lake outburst flood affected the velocity of the Lemon Creek Glacier in southeastern Alaska. Lemon Creek Glacier is a moderately sized (~16~km2) temperate glacier at the margin of the Juneau Icefield. An ice- marginal lake forms at the head of the glacier and catastrophically drains once or twice every melt season. We have instrumented the glacier with two meteorological stations: one at the head of the glacier near the ice-marginal lake and another several kilometers below the terminus. These stations measure temperature, relative humidity, precipitation, incoming solar radiation and wind speed and direction. Lake stage in the ice- marginal lake was monitored with a pressure transducer. In addition, Lemon Creek was instrumented with a water quality sonde at the location of a US Geological Survey gaging station approximately 3 km downstream from the glacier terminus. The sonde provides continuous measurements of water temperature, dissolved oxygen, turbidity and conductivity. Finally, two Trimble NetRS dual frequency, differential GPS units were deployed on the glacier at approximately 1/3 and 2/3 down the centerline of the glacier. All of the instruments were run continuously from May-September 2008 and captured the outburst flood associated with the ice-marginal lake drainage as well as several large (>3~cm) rainfall events associated with frontal storms off of the Gulf of Alaska in late summer. Taken together, these data allow us to test the hypothesis that water inputs which overwhelm subglacial drainage networks result in increased rates of basal motion.
Raup, B. H.; Khalsa, S. S.; Armstrong, R.
The Global Land Ice Measurements from Space (GLIMS) project has built a geospatial and temporal database of glacier data, composed of glacier outlines and various scalar attributes. These data are being derived primarily from satellite imagery, such as from ASTER and Landsat. Each "snapshot" of a glacier 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 glacier layers from our site over the Internet, or retrieve glacier 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 glacierized 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 glacier outlines from 2002 only, or from Autumn in any year, can be displayed. The system allows users to download their selected glacier 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), MapInfo, GML (Geography Markup Language) and GMT (Generic Mapping Tools). This "clip-and-ship" function allows users to download only the data they are interested in. Our flexible web interfaces to the database, which includes various support layers (e.g. a layer to help collaborators identify satellite imagery over their region of expertise) will facilitate enhanced analysis to be undertaken on glacier systems, their distribution, and their impacts on other Earth systems.
View eastward along Black Rapids Glacier. The Denali fault follows the trace of the glacier. These very large rockslides went a mile across the glacier on the right side. Investigations of the headwall of the middle landslide indicate a volume at least as large as that which fell, has dropped a mete...
Williams, Richard S., Jr.; Ferrigno, Jane G.
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 glaciers. 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 glacier 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 glaciers in coastal areas and islands beyond the margin of the ice sheet.
Sakai, A.; Nuimura, T.; Fujita, K.; Takenaka, S.; Nagai, H.; Lamsal, D.
Among meteorological elements, precipitation has a large spatial variability and less observation, particularly in high-mountain Asia, although precipitation in mountains is an important parameter for hydrological circulation. We estimated precipitation contributing to glacier mass at the median elevation of glaciers, which is presumed to be at equilibrium-line altitude (ELA) such that mass balance is zero at that elevation, by tuning adjustment parameters of precipitation. We also made comparisons between the median elevation of glaciers, including the effect of drifting snow and avalanche, and eliminated those local effects. Then, we could obtain the median elevation of glaciers depending only on climate to estimate glacier surface precipitation. The calculated precipitation contributing to glacier mass can elucidate that glaciers in arid high-mountain Asia receive less precipitation, while much precipitation makes a greater contribution to glacier mass in the Hindu Kush, the Himalayas, and the Hengduan Shan due to not only direct precipitation amount but also avalanche nourishment. We classified glaciers in high-mountain Asia into summer-accumulation type and winter-accumulation type using the summer-accumulation ratio and confirmed that summer-accumulation-type glaciers have a higher sensitivity than winter-accumulation-type glaciers.
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 glacier, Kangerdlugssuaq in southeast Greenland, thinning has been as much as 10 m/yr. This study examines the albedo variability in four outlet glaciers 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 glaciers, there has been a negative trend in albedo at the glacier terminus from 1981 to 2000, whereas the Stor+strommen and Kangerdlugssuaq glaciers 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 glacier, even larger changes in albedo have been observed, with decreases as much as 20 percent per decade.
The Wind Powering America program produces a poster at the end of every calendar year that depicts new U.S. wind energy projects. The 2008 poster includes the following projects: Stetson Wind Farm in Maine; Dutch Hill Wind Farm in New York; Grand Ridge Wind Energy Center in Illinois; Hooper Bay, Alaska; Forestburg, South Dakota; Elbow Creek Wind Project in Texas; Glacier Wind Farm in Montana; Wray, Colorado; Smoky Hills Wind Farm in Kansas; Forbes Park Wind Project in Massachusetts; Spanish Fork, Utah; Goodland Wind Farm in Indiana; and the Tatanka Wind Energy Project on the border of North Dakota and South Dakota.
Northern Illinois University offers illustrative summary of glaciers and glacial processes. The website provides a timeline of the glacial advances into Illinois. Students and educators can learn a few of the landscape features that scientists use to interpret geologic history. Users can learn how glaciers affected Illinois's topography and waterbodies. The site furnishes educational maps of Illinois's bedrock geology and shaded relief. The text is linked to a glossary to assist users with glacial terminology. While this website does concentrate on the state of Illinois, everyone can learn basic characteristics of glacial movements.
Dalla Fontana, G.; Carturan, L.; Cazorzi, F.
Distributed models of snow and ice mass balance enable a better understanding of processes involved in glacier hydrology and the prediction of glacier runoff under possible future climatic scenarios. The so-called 'Enhanced Temperature-Index' (ETI) melt models are a good compromise between model simplicity, parsimony of input data, and the capability to account for dominant processes in snow and ice mass balance. Accurate spatial calculation of temperature input data is crucial, given the key role of air temperature in modeling ablation and accumulation processes, further emphasized in ETI models. Compared to ambient conditions, lower temperatures (the so-called glacier cooling effect), and temperature variability (the so-called glacier damping effect) generally occur over glaciers, complicating the extrapolation from off-glacier weather stations. A comprehensive dataset of mass balance measurements and high-altitude meteorological observations was collected on La Mare and Careser glaciers (Ortles-Cevedale, Italian Alps) in 2010 and 2011. This dataset was used to analyze the air temperature distribution and wind regime over the glaciers, and to evaluate the impact of different calculation methods proposed in the literature for calculating on-glacier temperatures from off-glacier data. A general-purpose ETI model (EISModel - Energy Index Snow-and-ice Model) was used for simulating snow and ice accumulation and melt processes. Results indicate that i) none of the existing methods fully accounts for the actual temperature distribution over glaciers, ii) even small deviations in air temperature calculations strongly impact the simulations, and iii) there is an important positive feedback related to glacier shrinking and disintegration. Among the tested methods, the more physically-based procedure of Greuell and Bohm (1998) provided the best overall results. Therefore, it was implemented in EISModel for distributed air temperature calculations over glaciers.
This site contains lecture notes to accompany one chapter/lecture of a physical geology course using the text, The Dynamic Earth: An Introduction to Physical Geology, 4th Edition, by Brian J. Skinner and Stephen C. Porter. Subtopics include glaciers, glacial deposits, glacial features, glaciation, and glacial ages.
Suarez, Wilson; Macedo, Nicolás; Montoya, Nilton; Arias, Sandro; Schauwecker, Simone; Huggel, Christian; Rohrer, Mario; Condom, Thomas
The Peruvian Andes host about 71% of all tropical glaciers. Although several studies have focused on glaciers of the largest glaciered mountain range (Cordillera Blanca), other regions have received little attention to date. In 2011, a new program has been initiated with the aim of monitoring glaciers in the centre and south of Peru. The monitoring program is managed by the Servicio Nacional de Meteorología e Hidrología del Perú (SENAMHI) and it is a joint project together with the Universidad San Antonio Abad de Cusco (UNSAAC) and the Autoridad Nacional del Agua (ANA). In Southern Peru, the Quisoquipina glacier has been selected due to its representativeness for glaciers in the Cordillera Vilcanota considering area, length and orientation. The Cordillera Vilcanota is the second largest mountain range in Peru with a glaciated area of approximately 279 km2 in 2009. Melt water from glaciers in this region is partly used for hydropower in the dry season and for animal breeding during the entire year. Using Landsat 5 images, we could estimate that the area of Quisoquipina glacier has decreased by approximately 11% from 3.66 km2 in 1990 to 3.26 km2 in 2010. This strong decrease is comparable to observations of other tropical glaciers. In 2011, a meteorological station has been installed on the glacier at 5180 m asl., measuring air temperature, wind speed, relative humidity, net short and longwave radiation and atmospheric pressure. Here, we present a first analysis of air temperature and the radiation budget at the Quisoquipina glacier for the first three years of measurements. Additionally, we compare the results from Quisoquipina glacier to results obtained by the Institut de recherche pour le développement (IRD) for Zongo glacier (Bolivia) and Antizana glacier (Ecuador). For both, Quisoquipina and Zongo glacier, net shortwave radiation may be the most important energy source, thus indicating the important role of albedo in the energy balance of the glacier surface. This indicates the importance of understanding the role of snow cover in ablation processes of tropical glaciers.
This slide show follows a snowflake through its life in a glacier. The path of the ice crystal is traced from its incorporation in the zone of accumulation, through the zone of ablation to its final departure, whether being calved as an iceberg or melting or sublimated. There is also information on the speed of the glacier and the difference between a cold and a warm glacier.
This is the homepage of Glacier National Park. Users can access materials on the park's ecology and environment (plants and animals, biodiversity and air quality, geology, and fires), the culture and history of the park, park activities, and publications on naturalist activities. There are also video clips of park wildlife and scenery, a photo gallery, and live webcams. Links are provided to additional information, such as research activities on bear DNA and global climate change.
Bidlake, William R.; Josberger, Edward G.; Savoca, Mark E.
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 2006 and 2007. Mass balances were computed with assistance from a new model that was based on the works of other glacier researchers. The model, which was developed for mass balance practitioners, coupled selected meteorological and glaciological data to systematically estimate daily mass balance at selected glacier sites. The North Cascade Range in the vicinity of South Cascade Glacier accumulated approximately average to above average winter snow packs during 2006 and 2007. Correspondingly, the balance years 2006 and 2007 maximum winter snow mass balances of South Cascade Glacier, 2.61 and 3.41 meters water equivalent, respectively, were approximately equal to or more positive (larger) than the average of such balances since 1959. The 2006 glacier summer balance, -4.20 meters water equivalent, was among the four most negative since 1959. The 2007 glacier summer balance, -3.63 meters water equivalent, was among the 14 most negative since 1959. The glacier continued to lose mass during 2006 and 2007, as it commonly has since 1953, but the loss was much smaller during 2007 than during 2006. The 2006 glacier net balance, -1.59 meters water equivalent, was 1.02 meters water equivalent more negative (smaller) than the average during 1953-2005. The 2007 glacier net balance, -0.22 meters water equivalent, was 0.37 meters water equivalent less negative (larger) than the average during 1953-2006. The 2006 accumulation area ratio was less than 0.10, owing to isolated patches of accumulated snow that endured the 2006 summer season. The 2006 equilibrium line altitude was higher than the glacier. The 2007 accumulation area ratio and equilibrium line altitude were 0.60 and 1,880 meters, respectively. Accompanying the glacier mass losses were retreat of the terminus and reduction of total glacier area. The 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.
This animated model shows the predicted effects of glacial melting and changes in vegetation patterns in the Blackfoot-Jackson Glacier Basin of Glacier National Park, Montana. The scenario incorporated in the model consists of a predicted exponential rise in atmospheric CO2 concentrations, a 2xCO2 global warming scenario, with a concurrent warming of 2-3 degrees centigrade (4-5 degrees Fahrenheit) by the year 2050. In addition, it assumes that precipitation, primarily in the form of rain, will increase over the same time period about 10 percent. The animation is accompanied by a set of still images displaying intermediate steps used in the calculations of the ecological components, such as terrain characteristics, sun impact, soil moisture, and wind.
This August 1950 photo documents the significant changes that occurred during the 9 years between photographs A and B. Muir Glacier has retreated more than 2 miles, exposing Muir Inlet, and thinned 340 feet or more. However, it still is connected with tributary Riggs Glacier....
This August 2004 photo further documents the significant changes that have occurred during the 63 years between photographs A and C, and during the 54 years between photographs B and C. Muir Glacier has retreated out of the field of view and is now nearly 5 miles to the northwest. Riggs Glacier has ...
I magine Montana's Glacier National Park without glaciers; California's Joshua Tree National Park with no Joshua trees; or the state's Sequoia National Park with no sequoias. In 50 years' time, climate change plagued by tree pests, abetted by warmer temperatures. Fires are expected to become more frequent, animal
Pettit, E.C.; Nystuen, J.A.; O'Neel, Shad
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.
In this lesson, students will investigate how glaciers affect the landscape in the context of wondering how the rocks used in the stone walls first got into the ground. Following a directed reading and discussion, they will perform an activity in which they use ice cubes and a bucket of sand to simulate the effects of a glacier.
Paris-Sud XI, Université de
TCD 1, 1739, 2007 Glacier balance measurement, forecasting M. S. Pelto Title Page Abstract The Cryosphere Discussions is the access reviewed discussion forum of The Cryosphere Glacier annual balance balance measurement, forecasting M. S. Pelto Title Page Abstract Introduction Conclusions References
An interactive slide show explores the journey of a single snowflake onto and through a glacier. This journey, which can take as much as 30,000 years to complete, shows that the life cycle of a glacier can be more complex than originally perceived.
Meier, Mark; Lundstrom, Scott; Stone, Dan; Kamb, Barclay; Engelhardt, Hermann; Humphrey, Neil; Dunlap, William W.; Fahnestock, Mark; Krimmel, Robert M.; Walters, Roy
Measurements of glacier flow velocity and basal water pressure at two sites on Columbia Glacier, Alaska, are combined with meteorological and hydrologic data to provide an observational basis for assessing the role of water storage and basal water pressure in the rapid movement of this large glacier. During the period from July 5 to August 31, 1987, coordinated observations were made of glacier surface motion and of water level in five boreholes drilled to (or in one case near to) the glacier bed at two sites, 5 and 12 km from the terminus. Glacier velocities increased downglacier in this reach from about 4 m/d to about 7 m/d. Three types of time variation in velocity and other variables were revealed: (1) Diurnal fluctuation in water input/output, borehole water level, and ice velocity (fluctuation amplitude 5 to 8%); (2) Speed-up events in glacier motion (15-30% speed-up), lasting about three days, and ocurring at times of enhanced input of water, in some cases from rain and in others from ice ablation enhanced by strong, warm winds; (3) 'Extra-slowdown' events, in which, after a speed-up event, the ice velocity decreased in about 3 days to a level consistently lower than that prior to the speed-up event. All of the time variations were due, directly or indirectly, to variations in water input to the glacier.
Gerbaux, M.; Genthon, C.; Etchevers, P.; Vincent, C.; Dedieu, J. P.
A new physically based distributed surface mass-balance model is presented for Alpine glaciers. Based on the Crocus prognostic snow model, it resolves both the temporal (1 hour time-step) and spatial (200 m grid-step) variability of the energy and mass balance of glaciers. Mass-balance reconstructions for the period 1981 2004 are produced using meteorological reconstruction from the SAFRAN meteorological model for Glacier de Saint-Sorlin and Glacier d'Argentière, French Alps. Both glaciers lost mass at an accelerated rate in the last 23 years. The spatial distribution of precipitation within the model grid is adjusted using field mass-balance measurements. This is the only correction made to the SAFRAN meteorological input to the glacier model, which also includes surface atmospheric temperature, moisture, wind and all components of downward radiation. Independent data from satellite imagery and geodetic measurements are used for model validation. With this model, glacier sensitivity to climate change can be separately evaluated with respect to a full range of meteorological parameters, whereas simpler models, such as degree-day models, only account for temperature and precipitation. We provide results for both mass balance and equilibrium-line altitude (ELA) using a generic Alpine glacier. The sensitivity of the ELA to air temperature alone is found to be 125 m °C-1, or 160 m °C-1 if concurrent (Stefan Boltzmann) longwave radiation change is taken into account.
2000-01-01This ASTER images 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 glacier, covered with crevasses. A semi-circular terminal moraine indicates that the glacier was once more extensive than at present. ASTER data are being acquired over hundreds of glaciers worldwide to measure their changes over time. Since glaciers 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. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats, monitoring potentially active volcanoes, identifying crop stress, determining cloud morphology and physical properties, wetlands Evaluation, thermal pollution monitoring, coral reef degradation, surface temperature mapping of soils and geology, and measuring surface heat balance.
Brun, F.; Dumont, M.; Wagnon, P.; Berthier, E.; Azam, M. F.; Shea, J. M.; Sirguey, P.; Rabatel, A.; Ramanathan, Al.
Few glaciological field data are available on glaciers in the Hindu Kush - Karakoram - Himalaya (HKH) region, and remote sensing data are thus critical for glacier studies in this region. The main objectives of this study are to document, using satellite images, the seasonal changes of surface albedo for two Himalayan glaciers, Chhota Shigri Glacier (Himachal Pradesh, India) and Mera Glacier (Everest region, Nepal), and to reconstruct the annual mass balance of these glaciers based on the albedo data. Albedo is retrieved from MODerate Imaging Spectroradiometer (MODIS) images, and evaluated using ground based measurements. At both sites, we find high coefficients of determination between annual minimum albedo averaged over the glacier (AMAAG) and glacier-wide annual mass balance (Ba) measured with the glaciological method (R2 = 0.75). At Chhota Shigri Glacier, the relation between AMAAG found at the end of the ablation season and Ba suggests that AMAAG can be used as a proxy for the maximum snowline altitude or equilibrium line altitude (ELA) on winter accumulation-type glaciers in the Himalayas. However, for the summer-accumulation type Mera Glacier our approach relied on the hypothesis that ELA information, mostly not accessible from space during the monsoon, was still preserved later thanks to strong winter winds blowing away snow and in turn exposing again the late monsoon surface. AMAAG was subsequently revealed in the post-monsoon period. Reconstructed Ba at Chhota Shigri Glacier agrees with mass balances previously reconstructed using a positive degree-day method. Reconstructed Ba at Mera Glacier is affected by heavy cloud cover during the monsoon, which systematically limited our ability to observe AMAAG at the end of the melting period. In addition, the relation between AMAAG and Ba is constrained over a shorter time period for Mera Glacier (6 years) than for Chhota Shigri Glacier (11 years). Thus the mass balance reconstruction is less robust for Mera Glacier than for Chhota Shigri Glacier. However our method shows promising results and may be used to reconstruct the annual mass balance of glaciers with contrasted seasonal cycles in the western part of the HKH mountain range since the early 2000s when MODIS images became available.
Fountain, A. G.
In the 19th century measuring glacier change was limited to measuring the position of the glacier front, or terminus. By the mid 20th century, change measurements expanded to include aerial photogrammetry and field-based mass balance methods. The latter were typically based on stakes drilled into a glacier, against which snow accumulation and ice loss were measured. Knowing the density of the surface material and area of the glacier, the mass change can be calculated. This approach still provides the most detailed information on glacier mass change. At the turn of the new millennium, the increased sophistication of aerial and satellite remote sensing technology and computer software have provided numerous new approaches to assessing glacier change. In particular, airborne laser altimetry can be used to define the altitude of a glacier surface and over time provides changes in glacier volume. Traditional aerial photogrammetry has been revitalized by tracking feature displacement to provide a displacement field over the glacier surface and inferring point estimates of mass change based on a numerical model of continuity. The same technique can be used with a scanning laser altimeter. Satellite images can be used to track glacier change both in the form of aerial changes and by feature tracking. However due to current image resolutions the satellite imagery has been restricted to large ice fields on ice sheets. This may change in the near future. Synthetic aperture radar (SAR) satellites provide an enormous potential for tracking glaciers because interferometric techniques can also be used to infer a displacement field, and surface features can be investigated such as the snow line, and the transition between wet and dry snow. The all weather capabilities of SAR including day/night imaging, make it a particularly attractive sensor. One has to be clear, however, that these various techniques provide somewhat different information about glacier change and some caution must be taken when comparing the results of these methods. Databases of glacier change has largely been the responsibility of the World Glacier Monitoring Service (WGMS). That database is based on scalar quantities of glacier geometries and change, such as, mass change, length change, mean elevation, and so on. When first established it was the only practical type of database. With the rapid development of increasing computer memory and speed, and analytic software, particularly geographic information systems (GIS), we are no longer restricted to scalar databases. Within a GIS we can store, in digital form, historic maps of glacier surfaces, aerial photography including digital orthophotoquadrangles, satellite imagery and products derived from laser altimetry. In addition, we can store interpretative products and metadata including references to relevant scientific reports. Thus an investigator will have the original data and derived products at their disposal. The availability of original data is particularly important in view of expected future advances in computational methods. A GIS database will contribute to the WGMS efforts and accelerate our ability to exchange data internationally and increase our understanding of the spatial and temporal components of glacier change. Current efforts in this direction need to be encouraged and expanded.
created by Mark Francek, Central Michigan University The following are potential questions that could be used in a gallery walk activity about glaciers. The questions are organized according to the cognitive level ...
Turrin, James Bradley
Over 300 of the largest glaciers in southern Alaska have been identified as either surge-type or pulse-type, making glaciers with flow instabilities the norm among large glaciers in that region. Consequently, the bulk of mass loss due to climate change will come from these unstable glaciers 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 glacier flow, the decadal-scale ice dynamics of 1 surging and 9 pulsing glaciers are investigated. Bering Glacier 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 Glacier 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 glaciers are identified based on the spatiotemporal pattern of their velocity fields. These glaciers 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 glaciers. It is based on the concept of glaciohydraulic supercooling, and includes sediment transport and erosion along an adverse slope, ice thickening, and ablation of the ice surface such that the ratio of the angle of the adverse slope to ice surface slope oscillates around the supercooling threshold.
J. Corripio; U. Strasser; P. Burlando; M. Funk; F. Pellicciotti; B. Brock
From May to September 2001 a series of field observations have been performed on Haut Glacier Arolla (Swiss Alps): among others, five meteorological stations, posi- tioned on snow or ice, continuously recorded temperature, humidity, wind speed and albedo. Precipitation can be regionalized from an automatic weather station which is situated in the valley below the glacier. A standard 35 mm
Hågvar, Sigmund; Ohlson, Mikael
Glaciers are retreating and predatory invertebrates rapidly colonize deglaciated, barren ground. The paradox of establishing predators before plants and herbivores has been explained by wind-driven input of invertebrate prey. Here we present an alternative explanation and a novel glacier foreland food web by showing that pioneer predators eat locally produced midges containing 21,000 years old ancient carbon released by the melting glacier. Ancient carbon was assimilated by aquatic midge larvae, and terrestrial adults achieved a radiocarbon age of 1040 years. Terrestrial spiders, harvestmen and beetles feeding on adult midges had radiocarbon ages of 340-1100 years. Water beetles assumed to eat midge larvae reached radiocarbon ages of 1100-1200 years. Because both aquatic and terrestrial pioneer communities use ancient carbon, the term "primary succession" is questionable in glacier forelands. If our "old" invertebrates had been collected as subfossils and radiocarbon dated, their age would have been overestimated by up to 1100 years. PMID:24084623
Hågvar, Sigmund; Ohlson, Mikael
Glaciers are retreating and predatory invertebrates rapidly colonize deglaciated, barren ground. The paradox of establishing predators before plants and herbivores has been explained by wind-driven input of invertebrate prey. Here we present an alternative explanation and a novel glacier foreland food web by showing that pioneer predators eat locally produced midges containing 21,000 years old ancient carbon released by the melting glacier. Ancient carbon was assimilated by aquatic midge larvae, and terrestrial adults achieved a radiocarbon age of 1040 years. Terrestrial spiders, harvestmen and beetles feeding on adult midges had radiocarbon ages of 340–1100 years. Water beetles assumed to eat midge larvae reached radiocarbon ages of 1100–1200 years. Because both aquatic and terrestrial pioneer communities use ancient carbon, the term “primary succession” is questionable in glacier forelands. If our “old” invertebrates had been collected as subfossils and radiocarbon dated, their age would have been overestimated by up to 1100 years. PMID:24084623
Basagic, H.; Fountain, A. G.; Clark, D. H.
Alpine glaciers cover an area of about 553 km2 in seven western states of the American West. With few exceptions, all glaciers have been shrinking over the past century and the rate of shrinkage has accelerated over the past few decades. Overall, smaller glaciers exhibit greatest shrinkage, relative to their size, compared to larger glaciers. Preliminary results from studies of glacier change in several national parks reveal the spatial pattern of glacier change. Glacier shrinkage, while contributing to global sea level change, has two important local effects. First, the net release of water from its storage in the frozen state enhances overall stream discharge. Second, the shrinking area of glaciers reduces their moderating effect on stream flow, particularly during late-summer and drought periods, and shifts peak runoff towards early summer. Consequently these alpine basins become more susceptible to future drought. In addition to these "clean" glaciers, debris-covered glaciers are probably important as well. Debris-covered glaciers melt at much slower rates than adjacent "clean" glaciers, with reduced daily variations in melt because of the insulation provided by the surface debris layer. The number and extent of debris-covered glaciers in the American west is not well known therefore their hydrological contribution is uncertain. However, if the number of debris-covered glaciers can be scaled from an inventory of those in the Rocky Mountain National Park (Achuff, 2003), the volume of debris-covered ice may be considerable. From an ecological perspective, the greatest effects are in the high alpine regions where glacier recession opens new areas for biological expansion, and where the hydrological dependence on glaciers is greatest. Lesser effects, related to suspended sediment loads, are felt well downstream (10's km) from glaciers.
Su, Fengge; Ren, Zheng; Xu, Baiqing; Kan, Baoyun; Xie, Ying
A distributed energy-based glacier model coupled with a land surface hydrology model is developed and validated over the Muji Glacier (39.1865° N, 73.746°E, 5532-4715 m above sea level, 2.42 km2) on the eastern edge of the Pamirs with meteorological measurements and mass balance stake records on the glacier. Surface energy fluxes and melt rates are simulated for each 30m × 30m grid cell at a 3-hourly resolution for the period July 2011 to September 2014. The inputs of the coupled model include daily maximum and minimum air temperature, daily precipitation, wind speed, slope and aspect, and elevation of each grid cell. A new scheme of downward shortwave and longwave radiation is developed based on the limited climate inputs. The simulated incoming shortwave and longwave radiation, and albedo are compared with the measurements from 3 automatic weather stations during July 2011-September 2014. The mass balance over each 30m × 30m grid cell is simulated for the entire Muji Glacier with the distributed energy balance model for the three water years. The simulated mass balance is validated with the stake records for both melt and accumulation seasons and the validation results are plausible. The coupled energy-based-glacier-hydrology model will be further validated at the basin scale with measured glacier runoff.
Kolahoi glacier, western Himalaya is located in Jammu and Kashmir, India between N 340 07'-340 12' and E 750 19'-750 23'. The glacier makes the head of Liddar valley and provides origin to west Liddar river, draining into river Jhelum. Kolahoi is characterized by the frontal activities of westerly winds from Dec to March-April and by dry subtropical climate during summer season. The glacier represents a twin glacier system with one branch from two sides of Kolahoi peak-east and west, merging together to form a common ablation zone and a north facing snout. The first recorded visit to Kolahoi Glacier was made by E. F. Neve in 1909. The earliest attempt to establish the quaternary glacial history of Liddar valley can be attributed to Grinlinton (1928) followed by Terra & Patterson (1939). As a result of their work, the quaternary glaciation of Liddar valley has been divided into a main series of four glacial and three interglacial epochs, of which the first two glaciations were more intensive than the later two. A significant result of this history has been that as compared with the interglacial periods the glacial periods were much shorter, in SW Kashmir. Presence of various glacial features of fourth stage, observed in the valley were correlated with the literature, coordinates taken through GPS and built on a GIS platform with overlyering of satellite image time series of recent decades. Decadal history of Kolahoi glacier deglaciation was reconstructed based on the satellite image time series, indirect volume-area scaling methods and field experiments, indicating variable retreat rate contributing to a total recession of 485m in the snout of glacier and an area loss of 15% in previous four decades, since 1965. Annual measurement of mass balance for Kolahoi glacier were conducted through glaciologic method since the first drilling of ablation stakes in 2008, which indicate a range from -2.0 m.w.e. to -3.5 m.w.e. per annum for the glacier. However, field observance of huge rock masses (height ~35m) getting exposed from the interior of glacier, and presence of a secondary snout at the west branch of Kolahoi glacier, indicate a greater degree of mass wasting and detachment of two glacier branches, than the inferences drawn through imageries and indirect assessment methods. Kolahoi being located close to famous religious spot, Amarnath, visited by >300,000 pilgrims during a single month of summer season, the probability of glacier experiencing the coupled vulnerability of climate change forcers along with local anthropogenic influences need to be examined in detail.
Antoine Rabatel; Vincent Jomelli; Philippe Naveau; Bernard Francou; Delphine Grancher
Fluctuations of the Charquini glaciers (Cordillera Real, Bolivia) have been reconstructed for the Little Ice Age (LIA) from a set of 10 moraines extending below the present glacier termini. A lichenometric method using the Rhizocarpon geographicum was used to date the moraines and reconstruct the main glacier fluctuations over the period. The maximum glacier extent occurred in the second half
Thomas R. Allen
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
Shi, Junchao; Menenti, Massimo
The climatic variables are supposed to be the influential factors for the summer accumulation type glaciers in the Nyainqêntanglha Range, Tibetan Plateau. There are certainly unique regional climate regimes within this area during different seasons. In the summer season, the prevailing regional climate is controlled by a plenty of moisture transported by the warm summer monsoons, while it is getting colder and drier by the westerlies from the inland of Eurasia in the winter season. The impact of the resultant local hydro-thermal condition fluctuation on the the glacier dynamics is still not well understood. In this study, the seasonal patterns of glacier behaviors are estimated in terms of glacier surface displacements under a certain climatological state (2006-2009). The glacier surface displacements are derived from Landsat imageries by using the feature tracking method. The land surface temperatures and precipitations are selected as the representative parameters of the regional climate in the Nyainqêntanglha Range. According to the tendency analysis, the apparent annual cycle of precipitation and land surface temperature are recognized. At the same time, the diurnal change of land surface temperature (>0°C mostly in the daytime,
vanderVeen, Cornelis; Abdalati, Waleed (Technical Monitor)
The objective of this project was to develop simple yet realistic models of Greenland outlet glaciers to better understand ongoing changes and to identify possible causes for these changes. Several approaches can be taken to evaluate the interaction between climate forcing and ice dynamics, and the consequent ice-sheet response, which may involve changes in flow style. To evaluate the icesheet response to mass-balance forcing, Van der Veen (Journal of Geophysical Research, in press) makes the assumption that this response can be considered a perturbation on the reference state and may be evaluated separately from how this reference state evolves over time. Mass-balance forcing has an immediate effect on the ice sheet. Initially, the rate of thickness change as compared to the reference state equals the perturbation in snowfall or ablation. If the forcing persists, the ice sheet responds dynamically, adjusting the rate at which ice is evacuated from the interior to the margins, to achieve a new equilibrium. For large ice sheets, this dynamic adjustment may last for thousands of years, with the magnitude of change decreasing steadily over time as a new equilibrium is approached. This response can be described using kinematic wave theory. This theory, modified to pertain to Greenland drainage basins, was used to evaluate possible ice-sheet responses to perturbations in surface mass balance. The reference state is defined based on measurements along the central flowline of Petermann Glacier in north-west Greenland, and perturbations on this state considered. The advantage of this approach is that the particulars of the dynamical flow regime need not be explicitly known but are incorporated through the parameterization of the reference ice flux or longitudinal velocity profile. The results of the kinematic wave model indicate that significant rates of thickness change can occur immediately after the prescribed change in surface mass balance but adjustments in flow rapidly diminish these rates to a few cm/yr at most. The time scale for adjustment is of the order of a thousand years or so.
McGrath, D.; Oneel, S.; Sass, L. C., III; Gusmeroli, A.; Arendt, A. A.; Wolken, G. J.; Kienholz, C.; McNeil, C.
Mass loss from Alaskan glaciers (-50 ± 17 Gt/a, 2003-2009) constitutes one of the largest contributions to global sea level rise outside of the Greenland and Antarctic ice sheets. The largest process-related uncertainties in this calculation arise from the difficulty in accurately measuring accumulation on glaciers and from the large variability of accumulation over a range of spatio-temporal scales. Further, the physical processes governing snow distribution in complex terrain elude model parameterization. Using ground-penetrating radar, constrained with probe and pit observations, we quantify the magnitude and variability of snow accumulation at six prominent glaciers throughout Alaska at the end of 2013 winter. We find that total SWE magnitude and variability are strongly controlled by the large-scale climate system (i.e. distance from the coastal moisture source along prevailing storm track). On average, total SWE decreases by 0.33 m per 100 km from the coast, while the SWE elevation gradient decreases by 0.06 m / 100 m per 100 km from the coast. SWE variability over small spatial scales (<200 m) is similar at most sites, although two glaciers exhibit notably low and high variability, likely related to their respective climatic provenance. On individual glaciers, strong elevation gradients, increasing from 0.07 m SWE / 100 m at the interior Gulkana Glacier to 0.30 m SWE / 100 m at the coastal Scott Glacier, exert the primary control on accumulation. Results from multi-variable linear regression models (based on topographic variables) find wind exposure/shelter is the most frequent secondary control on accumulation variability. Finally, we find strong agreement (<10% difference) between the radar derived and stake derived total SWE estimates at two glaciers in the USGS Benchmark Glacier Program.
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 tidewater glaciers. The work presented discusses preliminary satellite observations of concurrent changes in the North Water and Nares Strait polynyas and neighbouring tidewater glaciers in Greenland and the Canadian Arctic where notable thinning and acceleration of glaciers have been observed. Also included is an outline of how these observations will fit into a much wider project on the topic involving ocean, atmosphere and sea ice modelling and short-term and longer-term in-situ measurements.
Herman, Frédéric; Beyssac, Olivier; Lane, Stuart; Brughelli, Mattia; Leprince, Sebastien; Brun, Fanny
Most mountain ranges on Earth owe their morphology to the action of glaciers and icecaps over the last few million years. Our current understanding of how glaciers have modified mountainous landforms has mainly been driven through landscape evolution models. These have included an array of erosion laws and mainly progressed through the implementation of various levels of sophistication regarding ice dynamics, subglacial hydrology or thermodynamics of water flow. However, the complex nature of the erosion processes involved and the difficulty of directly examining the ice-bedrock interface of contemporary glaciers has precluded the establishment of a prevailing erosion theory. Here we quantify the spatial variations in ice sliding velocity and erosion rate of a fast-flowing Alpine glacier in New Zealand during a 5-month period. By combining high resolution 3D measurements of surface velocity from optical satellite imagery with the quantification of both the production and provenance of sediments by the glacier, we show that erosion rates are proportional to sliding velocity raised to a power of about two. This result is consistent with abrasion theory. Given that the ice sliding velocity is a nonlinear function of ice thickness and ice surface slope, the response of glacial erosion to precipitation changes is highly nonlinear. Finally, our ability to constrain the glacial abrasion law present opportunities to further examine the interaction between glaciation and mountain evolution.
Walters, R.A.; Dunlap, W.W.
During the summer of 1984 and 1985, laser measurements were made of the distance from a reference location to markers on the surface of the lower reach of Columbia Glacier, Alaska. The speed varies from 7 to 15 m/d and has three noteworthy components: 1) a low-frequency perturbation in speed with a time scale of days related to increased precipitation, 2) semidiurnal and diurnal variations related to sea tides, and 3) diurnal variations related to glacier surface melt. -from Authors
Carroll, D.; Sutherland, D.; Shroyer, E.; Nash, J. D.
The rate of mass loss from the Greenland Ice Sheet quadrupled over the last two decades and may be due in part to changes in ocean heat transport to marine-terminating outlet glaciers. Meltwater commonly discharges at the grounding line in these outlet glacier fjords, generating a turbulent upwelling plume that separates from the glacier face when it reaches neutral density. This mechanism is the current paradigm for setting the magnitude of net heat transport in Greenland's glacial fjords. However, sufficient observations of meltwater plumes are not available to test the buoyancy-driven circulation hypothesis. Here, we use an ocean general circulation model (MITgcm) of the near-glacier field to investigate how plume water properties, terminal height, centerline velocity and volume transport depend on the initial conditions and numerical parameter choices in the model. These results are compared to a hydrodynamic mixing model (CORMIX), typically used in civil engineering applications. Experiments using stratification profiles from the continental shelf quantify the errors associated with using far-field observatons to initialize near-glacier plume models. The plume-scale model results are then integrated with a 3-D fjord-scale model of the Rink Isbrae glacier/fjord system in west Greenland. We find that variability in the near-glacier plume structure can strongly control the resulting fjord-scale circulation. The fjord model is forced with wind and tides to examine how oceanic and atmospheric forcing influence net heat transport to the glacier.
Many glaciers around the world are melting, and new research is showing some of the dramatic details. Ulyana Horodyskyj, a graduate student at the Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado at Boulder, set up cameras to take time-lapse photographs of three lakes on a glacier in Nepal. This allowed her and her colleagues to see the supraglacial lake drain in real time for the first time, making it possible to estimate how much water was involved and how long it took for the lake to drain and refill. Horodyskyj said in a press conference at the AGU Fall Meeting that such observations of supraglacial lakes are valuable because in a warming climate, melting glaciers can lead to formation of supraglacial lakes.
Andreassen, L. M.; Elvehøy, H.; Kjøllmoen, B.
Glaciers in mainland Norway cover 2692 km2and span a large range from south to north. Glacier surface mass balance is monitored by the direct (also called glaciological, traditional or conventional) method and indirectly assessed by the geodetic (or cartographic) method. The current glacier monitoring programme includes direct surface mass-balance investigations on 14 glaciers. Since measurements started at Storbreen in 1949, mass balance has been measured on a total of 43 glaciers. The accuracy of the direct measurements depends on both the accuracy of the point observations and inter- and extrapolation of point values to spatially distributed values. Long series of measurements can be inhomogeneous because of changes in personnel, methods, and glacier topography. Reanalysing glacier mass balance series is recommended as standard procedure for every mass balance monitoring programme with increasing importance for long time series. Repeated, detailed glacier mapping by aerial photography and photogrammetric methods, and recently by laser scanning (LIDAR), have been performed to calculate geodetic mass balance. The geodetic results are used as an independent check of the direct method as well as to monitor volume, area and mass changes of glaciers that lack direct measurements. Since 2007, LIDAR campaigns have been conducted on a 1/3 of the glacier area in Norway including all current mass balance glaciers. The objectives of the surveys are to produce high quality digital elevation models (DEMs) and orthophotos to document the present state of the glaciers and assess glacier changes since previous surveys. Furthermore, the DEMs and orthophotos provide an accurate baseline for future repeated mapping and glacier change detection. Here we present geodetic mass balance results for Norway over the last 50 years and compare the results with the direct in-situ measurements where available. We also show examples of how glacier mass balance data are being reanalyzed including homogenization and uncertainty assessments, and, in cases of unexplained discrepancies, adjusting the (annual) glaciological to the (multi-annual) geodetic balances.
Nývlt, Daniel; Kopa?ková, Veronika; Láska, Kamil; Engel, Zbyn?k.
Antarctic Peninsula is one of the regions, which have been exposed to the most rapid warming of the Earth since 1950. Consequences of climate changes are clearly documented by recent disintegration of ice shelves on both sides of the Antarctic Peninsula as well as by the retreat of land-based glaciers. James Ross Island, located close to the northernmost tip of the Antarctic Peninsula, represents an excellent place to study changes in the glacier mass-balance and their sensitivity to a regional warming trend. Two different types of glaciers of the Ulu Peninsula, the Whisky Glacier and the Davies Dome have been studied. Multi-temporal remote sensing data (aerial photographs, Landsat MSS, TM and ETM+ and Aster satellite optical and thermal multispectral data) and field survey allowed detecting changes in extent (2-D) as well as calculating glacier mass-balance changes (3-D) for these two glaciers from 1977 to 2009. The Whisky Glacier is a well-delimited valley glacier located mostly below the local Equilibrium line altitude (ELA). The glacier with high-flow velocities is fed by an intensive snow accumulation caused by prevailing southwestern winds. The Whisky Glacier covers an area of 2.3 km2 and its altitude varies from 215 to 475 m a.s.l. The Davies Dome is a flat-bottom dome glacier. Significant parts of its surface are located above the ELA and limited flow velocities are characteristic for the most parts of its body. However, the Davies Dome has a single 500-700 m wide southwestern outlet flowing towards the Whisky Bay. The Davies Dome extends an area of 6.7 km2 and its altitude ranges from 0 to 514 m a.s.l. Both glaciers experienced massive extension of their ice tongues towards the Brandy Bay during the mid Holocene. Lateral moraines located in front of the both glaciers heading down to the left coast of the Brandy Bay document this event. According to the remote sensing data and field investigations both glaciers have retreated since 1977. Between 2006 and 2009 repeated mapping of the Davies Dome was carried out and the results showed that the largest retreat ranging from 10 to 20 m occurred in the NW flat part of the glacier. Digital elevation models calculated on bases of aerial stereo-photographs from 1979 and 2006 allowed us to define mass-balance changes of the studied glaciers. Ground Penetrating Radar measurements taken on both glaciers helped with mass-balance investigations, furthermore, made it possible to increase the accuracy of the 3-D models. Annual mass balance measurements on the Davies Dome indicated a mean ablation about 20 cm between 2006 and 2009. On the Whisky Glacier, a network of 20 ablation stakes was established just recently (February 2009). Therefore, another 3-year investigation is necessary to bring comparable results. Acknowledgments: This research has been undertaken within a framework of the project No. 205/09/1876 funded by the Czech Science Foundation and by the R & D project VaV SP II 1a9/23/07.
Gärtner-Roer, I.; Naegeli, K.; Huss, M.; Knecht, T.; Machguth, H.; Zemp, M.
One of the grand challenges in glacier research is to assess the total ice volume and its global distribution. Over the past few decades the compilation of a world glacier inventory has been well-advanced both in institutional set-up and in spatial coverage. The inventory is restricted to glacier surface observations. However, although thickness has been observed on many glaciers and ice caps around the globe, it has not yet been published in the shape of a readily available database. Here, we present a standardized database of glacier thickness observations compiled by an extensive literature review and from airborne data extracted from NASA's Operation IceBridge. This database contains ice thickness observations from roughly 1100 glaciers and ice caps including 550 glacier-wide estimates and 750,000 point observations. A comparison of these observational ice thicknesses with results from area- and slope-dependent approaches reveals large deviations both from the observations and between different estimation approaches. For glaciers and ice caps all estimation approaches show a tendency to overestimation. For glaciers the median relative absolute deviation lies around 30% when analyzing the different estimation approaches. This initial database of glacier and ice caps thickness will hopefully be further enlarged and intensively used for a better understanding of the global glacier ice volume and its distribution.
Since measurements of Jakobshavn Isbrae were first taken in 1850, the glacier has gradually receded, finally coming to rest at a certain point for the past 5 decades. However, from 1997 to 2003, the glacier has begun to recede again, this time almost doubling in speed. The finding is important for many reasons. For starters, as more ice moves from glaciers on land into the ocean, it raises sea levels. Jakobshavn Isbrae is Greenlands largest outlet glacier, draining 6.5 percent of Greenlands ice sheet area. The ice streams speed-up and near-doubling of ice flow from land into the ocean has increased the rate of sea level rise by about .06 millimeters (about .002 inches) per year, or roughly 4 percent of the 20th century rate of sea level increase. This animation shows a time-lapse sequence of the ice flowing toward the ocean. In recent years, even ice that has traditionally remained in place is now being pulled down to the edge of land.
Ponce, A.; Beaty, S. M.; Lee, C.; Lee, C.; Noell, A. C.; Stam, C. N.; Connon, S. A.
Kilimanjaro glaciers captured a history of microbial diversity and abundance of supraglacial habitats. We show that a majority of bacterial clones, as determined by bacterial 16S rRNA gene sequencing, are most closely related to those isolated from cold-water environments.
Ananichheva, Maria; Arendt, Anthony; Hagen, Jon-Ove; Hock, Regine; Josberger, Edward G.; Moore, R. Dan; Pfeffer, William Tad; Wolken, Gabriel J.
Projections of future rates of mass loss from mountain glaciers and ice caps in the Arctic focus primarily on projections of changes in the surface mass balance. Current models are not yet capable of making realistic forecasts of changes in losses by calving. Surface mass balance models are forced with downscaled output from climate models driven by forcing scenarios that make assumptions about the future rate of growth of atmospheric greenhouse gas concentrations. Thus, mass loss projections vary considerably, depending on the forcing scenario used and the climate model from which climate projections are derived. A new study in which a surface mass balance model is driven by output from ten general circulation models (GCMs) forced by the IPCC (Intergovernmental Panel on Climate Change) A1B emissions scenario yields estimates of total mass loss of between 51 and 136 mm sea-level equivalent (SLE) (or 13% to 36% of current glacier volume) by 2100. This implies that there will still be substantial glacier mass in the Arctic in 2100 and that Arctic mountain glaciers and ice caps will continue to influence global sea-level change well into the 22nd century.
Records of glacier fluctuations compiled by the World Glacier Monitoring Service can be used to derive an independent estimate of global warming during the last 100 years. Records of different glaciers are made comparable by a two-step scaling procedure: one allowing for differences in glacier geometry, the other for differences in climate sensitivity. The retreat of glaciers during the last
Schmidt, Susanne; Nüsser, Marcus
The widely discussed controversy about Himalayan glacier changes instigated a current boom in studies on a regional scale. In contrast to often simplified assumptions of general and mostly rapid glacier retreat, recent studies show a more complex pattern with stable, advancing and retreating glaciers. Furthermore, changes of debris covered glaciers are discussed controversial. Due to the great vertical span and steep relief, large ice streams in the Himalaya and Karakoram are often primarily fed by avalanches. Their impact on glacier mass balances is often unconsidered in present studies. However, Hewitt (2014) highlighted the crucial role of snow and ice re-distribution by avalanches for Karakoram glaciers. He used a concept of glacier typology based on different nourishment processes introduced at the beginning of the 20th century. By using this concept, Hewitt classified large glaciers in order to identify the effect of avalanches on the mass balance, because many Karakoram glaciers show low down-wasting or even thickening processes described as the "Karakoram anomaly" (Hewitt 2005). Also in the Nanga Parbat region, the western corner of the High Himalaya, the topography is characterized by steep rock walls with vertical distances up to 4700 m. The debris covered glaciers reach down to 2920 m a.s.l. and are regularly fed by small and large avalanches. Our field based investigations show that the glaciers are characterized by small retreating rates since 1857, when Adolph Schlagintweit has mapped them for the first time; others such as the Raikot Glacier are fluctuating since 1934. Furthermore, the extent of down-wasting varies between different glaciers. By using multi-temporal satellite data, topographical maps, sketches and terrestrial photographs changes of glacier lengths were measured. In order to calculate the down-wasting rates, a digital elevation model (DEM) with a spatial resolution of 30x30 m² was derived from the digitized contour lines of the topographic map of 1934 and compared to the SRTM-DEM. Furthermore, based on topographical parameters derived from the SRTM-DEM, the glaciers were classified, using Hewitt's concept. The area of steep rock walls and the ratio between accumulation and ablation zones were calculated for each glacier basin. References: Hewitt, K. 2005: The Karakoram anomaly? Glacier expansion and the 'elevation effect', Karakoram Himalaya. Mountain Research and Development 25 (4), S. 332-340 Hewitt, K. 2014: Glaciers of the Karakoram Himalaya: Glacial Environments, Processes, Hazards and Resources. Springer. Dordrecht.
Pellikka, P. K. E.
Glacier changes reflect local climate changes and are one of the most important direct indicators of global climate change. In general, the glaciers are retreating in Europe, but some glaciers are advancing. However, even in small areas glacier responses can be different. The application of glaciers as indicators requires sufficient amount of glaciers, which is possible only with remote sensing methods. Remote sensing data have been used for glacier monitoring from the late 19th century, first as terrestrial photographs, but later as aerial photographs. A new era began in the 1970’s as optical satellite data became available. Since late 1990’s the glacier monitoring could be performed with numerous satellite and airborne sensors ranging from satellite radar data to airborne laser scanner data. All together, the development of new remote sensing technologies and methods provides many possibilities for studies of glacier features and parameters. The glacier parameters of interest in operational monitoring are the changes of glacier area and volume, and the variation of glacier zones, such as snow, firn and ice. These parameters enable the estimation of relative volume change, AAR and equilibrium line, for example. Operational monitoring involves that the remote sensing data to be used is available continuously, the image processing methods are accurate and the processing chain is developed so that the derivation of the aimed parameters works fluently. The OMEGA project aims at the development of an operational glacier monitoring system applying all the potential remote sensing data. The objectives are to develop workflows and semi-automatic image processing methodologies for different data types in order to retrieve glacier parameters, to construct databases of the study glaciers and to develop the prototype of an operational monitoring system. The test glaciers are Hintereisferner in Austria and Engabreen in Norway. The deliverable of the project is the OMEGA system. The user groups are advanced users for data analysis and reprocessing and public users who seek well-produced glacier information. The system outputs are the information of the volume changes between two different dates and the determination of the glacier boundary and area extent. The implementation of the system consists of the definitions for the data and methods, the workflows for supplying data for different types of users and Geographic Information Network for exchanging data within the OMEGA system. The prototype for the OMEGA system has been implemented among OMEGA collaborators and it’s software components are currently under testing.
Measuring Greenland Glacier Dynamics with Remotely Sensed Data Steve Foga University of Kansas, Geography M.A. Student Photo by: Phil Pasquini The importance of studying glacier ice Study area Difference in ice velocity of Helheim Glacier...
5. GLACIER POINT ROAD VIEW AT SENTINEL DOME PARKING AREA. LOOKING E. GIS: N-37 42 43.8 / W-119 35 12.1 - Glacier Point Road, Between Chinquapin Flat & Glacier Point, Yosemite Village, Mariposa County, CA
1. PARKING LOT AT GLACIER POINT. HALF DOME AT CENTER REAR. LOOKING NE. GIS: N-36 43 45.8 / W-119 34 14.1 - Glacier Point Road, Between Chinquapin Flat & Glacier Point, Yosemite Village, Mariposa County, CA
B. H. Luckman
Dendrochronological studies at Robson and Bennington Glaciers have provided the first calendar dating of an early 'Little Ice Age' glacier advance in North America. Dates derived from in-situ stumps indicate that Robson Glacier began over-riding forest between c. AD 1142 and 1150 and continued until at least AD 1350. The highest rates of glacier advance (c. 3.8 m yr-1 )
Telling, Jon; Anesio, Alexandre M.; Tranter, Martyn; Irvine-Fynn, Tristram; Hodson, Andy; Butler, Catriona; Wadham, Jemma
Glacier surfaces contain a wide diversity of microorganisms and can host a range of microbial activities. However, microbial nutrient cycling on glaciers is poorly understood. This study is the first to document nitrogen fixation (nitrogenase activity) on glaciers and demonstrate its importance in supporting microbial growth. Rates of nitrogen fixation (nitrogenase activity) in cryoconite holes on three valley glaciers in Svalbard ranged from <2.0 to 99.9 ?mol ethylene m-2 d-1 with rates inversely correlated to concentrations of available inorganic nitrogen. Annual inputs of nitrogen by nitrogen fixation on a glacier catchment scale are more than 2 orders of magnitude lower than the combined nitrogen inputs from snowmelt and rain. However, nitrogen fixation can be important for supporting microbial growth on the glaciers during the middle to late melt season after the snowline has retreated upslope.
Sakai, A.; Fujita, K.
Debris-covered glaciers are common in many of the world's mountain ranges, including in the Himalayas. Himalayan debris-covered glacier also contain abundant glacial lakes, including both proglacial and supraglacial types. We have revealed that heat absorption through supraglacial lakes was about 7 times greater than that averaged over the whole debris-covered zone. The heat budget analysis elucidated that at least half of the heat absorbed through the water surface was released with water outflow from the lakes, indicating that the warm water enlarge englacial conduits and produce internal ablation. We observed some portions at debris-covered area has caved at the end of melting season, and ice cliff has exposed at the side of depression. Those depression has suggested that roof of expanded water channels has collapsed, leading to the formation of ice cliffs and new lakes, which would accelerate the ablation of debris-covered glaciers. Almost glacial lakes on the debris-covered glacier are partially surrounded by ice cliffs. We observed that relatively small lakes had non-calving, whereas, calving has occurred at supraglacial lakes with fetch larger than 80 m, and those lakes expand rapidly. In the Himalayas, thick sediments at the lake bottom insulates glacier ice and lake water, then the lake water tends to have higher temperature (2-4 degrees C). Therefore, thermal undercutting at ice cliff is important for calving processes in the glacial lake expansion. We estimated and subaqueous ice melt rates during the melt and freeze seasons under simple geomorphologic conditions. In particular, we focused on valley wind-driven water currents in various fetches during the melt season. Our results demonstrate that the subaqueous ice melt rate exceeds the ice-cliff melt rate above the water surface when the fetch is larger than 20 m with the water temperature of 2-4 degrees C. Calculations suggest that onset of calving due to thermal undercutting is controlled by water currents driven by winds at the lake surface with a positive feedback process. The risk of GLOFs (glacial lake outburst flood) are analysed for Himalayan glacial lakes. We proposed an objective index for GLOF probability, based on depression angle from the lakeshore, which allows the lakes to be assessed using remotely sensed digital elevation models (DEMs). The index was verified by pre-GLOF topography derived by spy satellite imageries. We screened 2800 Himalayan glacial lakes and identified 49 lakes with potential flood volumes over 10 million m3.
To prepare for this assignment students have already used Google Earth to examine beach erosion, but they have not yet created any new content with Google Earth. Students are already competent navigators and are accustomed to the perspective views used in Google Earth. In this assignment students first go through a prepared Google Earth tour on Juneau Icefield glaciers, and answer questions about glacier features. Then students create their own Google Earth tour, using placemarks to identify key features of their glacier.
Myrna H. P. Hall
Animation of Modeled Climate-Induced Glacier Change in Glacier National Park, 1850- 2100. The simulation reflects the predicted exponential rise in atmospheric CO2 concentrations, a 2xCO2 "global warming" scenario, with a concurrent warming of 2-3 degrees centigrade (4-5 degrees Fahrenheit) by the year 2050. In addition it assumes that precipitation, primarily in the form of rain, will increase over the same time period about 10 percent (based on the research of Dr. Steven Running, University of Montana). The animation view of the Blackfoot-Jackson basin along the Continental Divide, includes Gunsight Lake in the foreground and a portion of Lake Ellen Wilson visible over Gunsight Pass.
Maxwell, Bruce D.
prevalence (Heart Attack) 4.5% 4.1% 6.0% All Sites Cancer 461.9 (Region 2) 455.5 543.2 1 Community) Leading Causes of Death County1 Montana1,2 Nation2 1. Heart Disease 2. Cancer 3. Unintentional Injuries** 1. Cancer 2. Heart Disease 3.CLRD* 1. Heart Disease 2. Cancer 3. CLRD* #12; Glacier County
Naftz, D.L.; Smith, M.E.
Glaciological investigations of the Upper Fremont Glacier in the Wind River Range of Wyoming were conducted during 1990-1991. The glaciological data will provide baseline information for monitoring future changes to the glacier and support ongoing research utilizing glacial-ice-core composition to reconstruct paleoenvironmental records. Ice thickness, determined by radio-echo sounding, ranged from 60 to 172 m in the upper half of the glacier. Radio-echo sounding of ice thickness at one point was confirmed by drilling 159.7 m to bedrock. Annual ablation (including snow, firn, and ice) measured for the 1990-1991 period averaged about 0.93 m/a. Surface ice velocity and direction were monitored from July 1990 to August 1991. Ice velocity decreased in a downslope direction. The largest measured velocity was about 3.1 m/a and the smallest was 0.8 m/a. -from Authors
Raup, B. H.; Khalsa, S. J. S.; Armstrong, R.; Racoviteanu, A.
The Global Land Ice Measurements from Space (GLIMS) initiative has built a database of glacier outlines and related attributes, derived primarily from satellite imagery, such as from ASTER and Landsat. Each snapshot of a glacier is from a specific time, and the database is designed to store multiple snapshots representative of different times. The database currently contains outlines for approximately 83,000 glaciers. Of these, 549 glaciers have outlines from more than one time, which can be studied for change. The glacier-by-glacier area-change signal over large areas tends to be noisy, but the mode of the distribution of area change for these 549 glaciers is -5%. 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 creates interactive maps on our Web site, www.glims.org, and can also supply glacier layers to other servers over the Internet. As a service to the GLIMS community, the database contains metadata on all ASTER imagery (approximately 200,000 images) acquired over glacierized terrain. Reduced-resolution images can be viewed either as a layer in the MapServer application, or overlaid on the virtual globe within Google Earth. The system allows users to download their selected glacier 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), MapInfo, GML (Geography Markup Language) and GMT (Generic Mapping Tools). This "clip-and-ship" function allows users to download only the data they are interested in. In this presentation we describe our flexible Web interfaces to the database, which includes various ancillary layers, facilitates enhanced analysis of glacier systems, their distribution, and their impacts on other Earth systems.
Conway, J. P.; Cullen, N. J.
A thorough understanding of the influence of clouds on glacier surface energy balance (SEB) and surface mass balance (SMB) is critical for forward and backward modelling of glacier-climate interactions. A validated 22 month time series of SEB/SMB was constructed for the ablation zone of the Brewster Glacier, using high quality radiation data to carefully evaluate SEB terms and define clear-sky and overcast conditions. A fundamental change in glacier SEB in cloudy conditions was driven by increased effective sky emissivity and surface vapour pressure, rather than the minimal change in air temperature and wind speed. During overcast conditions, positive net longwave radiation and latent heat fluxes allowed melt to be maintained through a much greater length of time compared to clear-sky conditions, and led to similar melt in each sky condition. The sensitivity of SMB to changes in air temperature was greatly enhanced in overcast compared to clear-sky conditions due to more frequent melt and the occurrence of precipitation, which enabled a strong accumulation-albedo feedback. During the spring and autumn seasons, the sensitivity during overcast conditions was strongest. There is a need to include the effects of atmospheric moisture (vapour, cloud and precipitation) on melt processes when modelling glacier-climate interactions.
To date, there has only been little conceptual change research regarding conceptions about glaciers. This study used the theoretical background of embodied cognition to reconstruct different metaphorical concepts with respect to the structure of a glacier. Applying the Model of Educational Reconstruction, the conceptions of students and scientists…
This photo was taken in September 2003; in the 23 years between photographs, Muir Glacier has retreated more than a mile and ceased to have a tidewater terminus. Since 1980, Muir Glacier has thinned by more than 600 ft, permitting a view of a mountain with a summit elevation of greater than 4000 ft,...
CPD 4, 173211, 2008 Climate and glacier response to ENSO in subtropical Andes E. Dietze et al.0 License. Climate of the Past Discussions Climate of the Past Discussions is the access reviewed discussion forum of Climate of the Past Response of regional climate and glacier ice proxies to El Ni
Machguth, H.; Huss, M.
Glacier length is an important measure of glacier geometry but global glacier inventories are mostly lacking length data. Only recently semi-automated approaches to measure glacier length have been developed and applied regionally. Here we present a first global assessment of glacier length using a fully automated method based on glacier surface slope, distance to the glacier 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 glaciers around the globe. The evaluation highlights accurately calculated glacier length where DEM quality is good (East Greenland) and limited precision on low quality DEMs (parts of Alaska). Measured length of very small glaciers is subject to a certain level of ambiguity. The global calculation shows that only about 1.5% of all glaciers are longer than 10 km with Bering Glacier (Alaska/Canada) being the longest glacier 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 glacier mass balance. The present study adds glacier length as a central parameter to global glacier inventories. Global and regional scaling laws might proof beneficial in conceptual glacier models.
Lavrentiev, Ivan; Kutuzov, Stanislav; Vasilenko, Evgeny; Macheret, Yuri
Accurate glacier volume and ice-thickness estimations are highly important for many glaciological applications. Recent glacier 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 glacierized 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 glaciers 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 glaciers including biggest glacier in Caucasus - Bezengi (36 km2) most of which have a highly crevassed surfaces and heterogeneous internal structure. Independent data were obtained also for two glaciers 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 glaciers. Successful use of VIRL-6 radar in Caucasus opens up the possibility of using such equipment on different types of glaciers in polar and mountain regions, including temperate, polythermal and surging glaciers.
Bryce L. Carmichael; Amber E. Smith
Visual documentation of glaciers can provide daily, seasonal, and yearly statistics concerning their advance and retreat, as well as contribute to historical record. Recognizing how glaciers change will improve glacier models, which leads to a better understanding of climate and ice-sheet interactions. Obtaining frequent images of glaciers can be difficult since they are often located in remote locations with rugged
R. J. Braithwaite; F. Muller
The equilibrium line altitude (ELA) of a glacier is said to be an important characteristic of the glacier and a parameter representing it should be included in a glacier inventory. However, there are few glaciers whose ELA has been directly measured and furthermore ELAs appear to be highly variable from year to year in comparison with their secular variations. In
Pope, A.; Scambos, T. A.
Mountain glaciers and ice caps around the world are recognized as significant contributors to both global sea level and local and regional water resources, especially for arid regions. However, the remote and rugged nature of glaciers in many parts of Asia hinders their study. To complicate the picture, not only are glaciers in High Mountain / Central / North Asia exhibiting considerable regional variability in mass balance, but different measurement methods are painting significantly different pictures of glacier health. Mongolia provides a subset of the global glacier inventory which exemplifies low data availability and seemingly contradictory results. Based on previous studies, Mongolia is home to ~500 glaciers totaling ~650 km2, but these figures are quite rough. Regional glacier mass balance estimates vary from -2 × 1 Gt / yr to 3 × 6 Gt / yr. However, the glaciers are important to the local environment and agriculture, as Mongolian glaciers are estimated to store 10% of Mongolia's fresh water. The glaciers have lost ~6% of their area from the 1960s to the 1990s. Most recent studies of high mountain Asia (the large group of glaciated ranges between the Tien Shan, Qilian Mountains, and the Himalayas) show accelerated losses in recent years. Therefore, from within this uncertainty, we harness newly available data from Landsat 8's Operational Land Imager (OLI) to build an updated glacier inventory for Mongolia. Prior regional studies have focused of a variety of sub-ranges across many different epochs within the Altai (i.e. Munkh Khairkhan, Tavan Bogd, Turgen, Kharkhiraa, Munkhkhairkhan, Sair, and Tsambagarav Mountains); here, we unify the picture of recent change for all of Mongolia's glaciers (i.e., the additional glaciated areas eastward of the Altai). In addition to highlighting the ease and utility of Landsat 8's OLI, we will take advantage of a further suite of data (i.e. Landsat archival imagery, ICESat, ASTER, SPOT-5, or submeter imagery) to further document glacier change in the Mongolian Altai.
Vagliasindi, Marco; Funk, Martin; Faillettaz, Jerome; Dalban, Pierre; Lucianaz, Claudio; Diotri, Fabrizio; Motta, Elena; Margreth, Stephan
Grandes Jorasses serac is an unbalanced hanging glacier located on the south side of Mont Blanc Massif (Aosta Valley - Italy). It stands above Ferret Valley, a famous and most frequented touristic site both in winter and summer. Historical data and morphological evidences show that the glacier is subject to recurrent icefalls which can be dangerous especially in winter, as they can trigger catastrophic combined snow and ice avalanches. Serac dynamic was monitored in 1997-98 by prof. M Funk (ETH Zurich) by means of temperature and topographic measurement. These allowed to forecast the breakdown within a 2 days time. Thanks to a monitoring program, a new instability could be recognized in autumn 2008: a crevasse opening in the lower part of the hanging glacier. A new monitoring system was installed recently, consisting of stakes with prisms on serac surface and an automatic total station (theodolite plus distantiometer) sited on the valley floor. Monitoring is based on an empirically based power law (developed by ETH) that describes the increasing displacement rate before collapse. This monitoring system requires to measure displacement rate of the serac continuously. Although the topographic system is so far the state-of-the.art method, it implies some troubles: (i) the difficulty in placing stakes on the steep and dangerous glacier surface; (ii) potential instability of stakes themselves due to snow pressure in winter and surface ice melting in summer; (iii) impossibility to carry out measurement in case of cloudy or stormy weather, which is rather a frequent situation on Grandes Jorasses peak. Moreover, hazard and risk management require some more informations, such as the instable ice mass volume. New technologies have been applied, and are still under test, to achieve a more reliable monitoring system and a better understanding of the serac dynamics. Close-range photogrammetry techniques have been used, allowing to process helicopter-taken images and obtain quantitative data about the serac volume and crevasses widening. A low-cost GPS station has been installed in the upper part of the serac, in order to obtain long-term, continuous displacement data even in bad weather conditions. A seismograph has been installed to measure the seismic activity of the serac. The latter, as observed by ETH, significantly evolves before the seracfall; thus, the record of the seismic activity can be used to forecast the break-off. Finally, a ground-based SAR system has been tested to infer seracs displacement. Possible avalanches scenarios consequent to an icefall have been calculated by numerical simulation by the SLF Institute of Davos. In-situ measurement techniques have to be designed to resist often in the difficult environmental conditions (low temperature, frost, wind), dealing, e.g. with power supply and data transmission, and purpose-made technical solutions are often necessary. The development of these techniques will contribute to an improved understanding of the seracs dynamics and provide a more reliable monitoring tool.
Janke, Jason R.; Bellisario, Antonio C.; Ferrando, Francisco A.
In the Dry Andes of Chile (17 to 35° S), debris-covered glaciers and rock glaciers are differentiated from true glaciers based on the percentage of surface debris cover, thickness of surface debris, and ice content. Internal ice is preserved by an insulating cover of thick debris, which acts as a storage reservoir to release water during the summer and early fall. These landforms are more numerous than glaciers in the central Andes; however, the existing legislation only recognizes uncovered or semicovered glaciers as a water resource. Glaciers, debris-covered glaciers, and rock glaciers are being altered or removed by mining operations to extract valuable minerals from the mountains. In addition, agricultural expansion and population growth in this region have placed additional demands on water resources. In a warmer climate, as glaciers recede and seasonal water availability becomes condensed over the course of a snowmelt season, rock glaciers and debris-covered glaciers contribute a larger component of base flow to rivers and streams. As a result, identifying and locating these features to implement sustainable regional planning for water resources is important. The objective of this study is to develop a classification system to identify debris-covered glaciers and rock glaciers based on the interpretation of satellite imagery and aerial photographs. The classification system is linked to field observations and measurements of ice content. Debris-covered glaciers have three subclasses: surface coverage of semi (class 1) and fully covered (class 2) glaciers differentiates the first two forms, whereas debris thickness is critical for class 3 when glaciers become buried with more than 3 m of surface debris. Based on field observations, the amount of ice decreases from more than 85%, to 65-85%, to 45-65% for semi, fully, and buried debris-covered glaciers, respectively. Rock glaciers are characterized by three stages. Class 4 rock glaciers have pronounced transverse ridges and furrows that arch across the surface, which indicates flow produced via ice. Class 5 rock glaciers have ridges and furrows that appear linear in the direction of flow, indicating reduced flow from limited internal ice; and class 6 rock glaciers have subdued surface topography because the movement of the rock glacier has ceased. Ice content decreases from 25-45%, to 10-25%, to < 10% from class 4 to 6, respectively. Examples from digital imagery, aerial photographs, and field photographs are provided for each class. The classification scheme can be used to identify and map debris-covered glaciers and rock glaciers to create an inventory. This will help improve recognition of these landforms as an important water resource in the dry Andes of Chile, which will aid in sustainable planning and development in basins that hold the majority of the population and support a large share of the economic activity in Chile.
Wagnon, P.; Ramanathan, A. L.; Arnaud, Y.; Azam, F.; Vincent, C.
Two white Himalayan glaciers, Chhota Shigri Glacier (16 km2, 32°N, India, arid-monsoon transition climate) and Mera Glacier (10 km2, 27°N, Nepal, Indian monsoon climate) have been monitored for mass, energy and hydrological balances since 2002 and 2007 respectively. Both glaciers belong now to the GLACIOCLIM observatory aiming at monitoring over a long term selected glaciers representative of different climates of the world. Additionally, a debris-covered glacier, Changri Nup Glacier (4 km2, 28°N, Nepal) has been monitored for mass and energy balances since 2009. During the period 2002-2011, Chhota Shigri Glacier experienced a negative glacier-wide mass balance (MB) of -0.59 ± 0.40 m water equivalent per year (w.e. yr-1), measured with the glaciological method. A recent study of the dynamic behaviour of the glacier showed that the glacier has probably experienced a period of near zero or slightly positive mass balance in the 1990s, before shifting to an imbalance in the 21st century. There is no sign of large recession of glaciers in Lahaul and Spiti region (Northern India) over the last 2 decades, the ice wastage being only limited to the last decade. On Mera Glacier, between 2007 and 2011, the cumulative mass balance is very close to zero. Melting is mainly driven by the radiative fluxes, the albedo being a key variable of the surface energy balance. The turbulent fluxes are only important in winter, when melting is insignificant and sublimation high.
This paper presents results from recent environmental and anthropological research near glacierized areas in the department of Cusco, Peru, home to the well-known Quelccaya Ice Cap and to the peak of Ausangate (6384 m). Glaciers in the region are in negative mass balance, losing volume and area, with upslope movement of the glacier fronts. Somewhat paradoxically, flows in many streams close to the glaciers are reduced, particularly in the dry season, due to a shift in the seasonal distribution of melting, to increased evaporation and to increased percolation into newly-exposed sands and gravels. Associated with this reduction in flow is a desiccation of some anthropogenic and natural wetlands, reducing the availability of dry season forage to wild (vicuna) and domesticated (alpaca, llama) ruminants. Interviews and ethnographic observations with local populations of Quechua-speaking herders at elevations of 4500-5200 meters provide detailed comments on these changes. They have an extensive vocabulary of terms for glacial features associated with retreat. They link this treat with environmental factors (higher temperatures, greater winds that deposit dust on lower portions of glaciers) and with religious factors (divine punishment for human wrong-doing, failure of humans to respect mountain spirits). They describe a variety of economic and extra-economic impacts of this retreat on different spatial, social and temporal scales. Though they face other issues as well (threats of pollution from new mining projects, inadequacy of government services), glacier retreat is their principal concern. Many herders express extreme distress over this unprecedented threat to their livelihoods and communities, though a few propose responses - out-migration, the formation of an association of neighboring communities, development of irrigation works - that could serve as adaptations.
Nolin, A. W.; Mar, E.
The surface of the Greenland ice sheet is shaped by wind, melt, and glacier dynamics. Surface roughness affects the surface-atmospheric interactions (via the aerodynamic roughness length) and thus influences fluxes of sensible and latent heat at the ice sheet surface. When combined with near-infrared reflectance, surface roughness has been shown to discriminate between glacier zones. We present the first ever annual time series of Greenland ice sheet surface roughness derived from the Multi-angle Imaging SpectroRadiometer (MISR) for the years 2000-2013. Our cloud-free multi-angular measurements are calibrated using airborne LiDAR data from the Airborne Topographic Mapper (ATM). Roughness values range from 10 cm in the dry, snow-covered interior of the ice sheet to over 8 m along the crevassed margins of the ice sheet. Roughness increases from April to July as the surface melts and glaciers become more active. Our roughness maps are restricted to spring and early summer due to limited ATM data. We next employed ISODATA unsupervised clustering with MISR near-infrared reflectance and surface roughness to map glacier zones on the ice sheet for years 2000-2013. The number and locations of the ISODATA-derived glacier zones are consistent from year to year with slight shifts in boundaries depending on the extent of early summer melt. These maps of Greenland ice surface roughness and glacier zones are the result of processing several hundred thousand MISR images and are the first ever full-coverage, annual maps of this kind.
Monnier, Sébastien; Kinnard, Christophe
The glacier to rock glacier transformation problem is revisited from a previously unseen angle. A striking case in the Juncal Massif (located in the upper Aconcagua Valley, Chilean central Andes) is documented. There, the Presenteseracae debris-covered glacier has advanced several tens of metres and has developed a rock glacier morphology in its lower part over the last 60 years. The conditions for a theoretically valid glacier to rock glacier transformation are discussed and tested. Permafrost probability in the area of the studied feature is highlighted by regional-scale spatial modelling together with on-site shallow ground temperature records. Two different methods are used to estimate the mean surface temperature during the summer of 2014, and the sub-debris ice ablation rates are calculated as ranging between 0.05 and 0.19 cm d- 1, i.e., 0.04 and 0.17 m over the summer. These low ablation rates are consistent with the development of a coherent surface morphology over the last 60 years. Furthermore, the rates of rock wall retreat required for covering the former glacier at Presenteseracae lie within the common 0.1-2 mm y- 1 range, assuming an average debris thickness and a range of debris-covering time intervals. The integration of the geomorphological observations with the numerical results confirms that the studied debris-covered glacier is evolving into a rock glacier.
Kincaid, Joni L.
Over the past century, glaciers throughout the tropics have predominately retreated. These small glaciers, which respond quickly to climate changes, are becoming increasingly important in understanding glacier-climate interactions. The glaciers...
Glowacki, O.; Deane, G. B.; Moskalik, M.; Blondel, Ph.; Tegowski, J.; Blaszczyk, M.
Climate-driven ice-water interactions in the contact zone between marine-terminating glaciers and the ocean surface show a dynamic and complex nature. Tidewater glaciers lose volume through the poorly understood process of calving. A detailed description of the mechanisms controlling the course of calving is essential for the reliable estimation and prediction of mass loss from glaciers. Here we present the potential of hydroacoustic methods to investigate different modes of ice detachments. High-frequency underwater ambient noise recordings are combined with synchronized, high-resolution, time-lapse photography of the Hans Glacier cliff in Hornsund Fjord, Spitsbergen, to identify three types of calving events: typical subaerial, sliding subaerial, and submarine. A quantitative analysis of the data reveals a robust correlation between ice impact energy and acoustic emission at frequencies below 200 Hz for subaerial calving. We suggest that relatively inexpensive acoustic methods can be successfully used to provide quantitative descriptions of the various calving types.
This text explains how glaciers scour and grind the Earth's surface, and about the sorts of deposits they leave behind. Emphasis is on glaciation in the mountains and valleys of Vermont. Links to related topics are included.
Steig, E.J.; Fitzpatrick, J.J.; Potter, N., Jr.; Clark, D.H.
A 9.5 m ice core was extracted from beneath the surficial debris cover of a rock glacier at Galena Creek, northwestern Wyoming. The core contains clean, bubble-rich ice with silty debris layers spaced at roughly 20 cm intervals. The debris layers are similar in appearance to those in typical alpine glaciers, reflecting concentration of debris by melting at the surface during the summer ablation season. Profiles of stable isotope concentrations and electrical conductivity measurements provide independent evidence for melting in association with debris layers. These observations are consistent with a glacial origin for the ice, substantiating the glacigenic model for rock glacier formation. The deuterium excess profile in the ice indicates that the total depth of meltwater infiltration is less than the thickness of one annual layer, suggesting that isotope values and other geochemical signatures are preserved at annual resolution. This finding demonstrates the potential for obtaining useful paleoclimate information from rock glacier ice.
The need for an inventory of the world's glaciers evolved during the International Hydrological Decade (1965-74). As a result, guidelines were established in the mid 1970s to compile a worldwide detailed inventory of existing perennial snow and ice masses. Following these international guidelines, several countries started compiling national glacier inventories based primarily on aerial photographs and maps. In the 1980s, the World Glacier Inventory (WGI) database was launched together with a status report about global and regional glacierised surface areas for the second half of the 20th century. These estimates were based on the detailed inventory data together with preliminary estimates of the remaining glacierised regions derived from early satellite imagery. In the late 1990s, the Global Land Ice Measurements from Space (GLIMS) database was initiated to continue the inventory task with space-borne sensors. In the WGI, glaciers are represented by geographical point coordinates. The GLIMS database includes digital outlines. Both include exact time stamps and tabular information on glacier classifications, length, area, orientation, and altitude range. Both are regularly updated with newly available data: the WGI stores point information for the second half of the 20th century whereas the GLIMS includes digital outlines for the 21st century. Since these detailed glacier inventories are not (yet) globally complete, there have been several efforts towards preliminary estimates of the overall global glacier coverage. A first, well elaborated one was included in the original status report of the WGI, published in 1989, and was refined in 2005 with information from other sources by Dyurgerov and Meier. Other studies used the detailed WGI, or an extended format by Cogley, for regional or global up-scaling of glacier extents. In 2003, Cogley published a global map of percentage glacier coverage per 1°x1° grid box (GGHydro) that is widely used for modeling at global scale. A first globally and almost complete map with (generalized) digital outlines of all ice covered regions (incl. Greenland but excluding Antarctica) was derived from ESRI's Digital Chart of the World (DCW) and other sources by Raup and colleagues in 2000. Most recently, Arendt and colleagues produced the Randolph dataset which combines available outlines from the GLIMS, DCW, and WGI datasets as well as from many other (often unpublished) sources by using the highest quality version in each region. However, while having the advantage of being almost complete, these global estimates lack time stamps and attributes for individual glaciers. The present work provides a brief review of the various efforts, its methodological differences, and findings towards the completion of a World Glacier Inventory.
Furfaro, R.; Kargel, J. S.; Fink, W.; Bishop, M. P.
Glaciers and ice sheets are among the largest unstable parts of the solid Earth. Generally, glaciers 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 glaciers are also commonly unstable due to landslide potential of moraines, debris flows, snow avalanches, outburst floods from glacier 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 glacier 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 glacier 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 glacier experts’ reasoning. Here, we introduce the theory of Fuzzy Cognitive Maps (FCM) as an AI tool for predicting and assessing natural hazards in alpine glacier environments. FCM techniques are employed to represent expert knowledge of glaciers 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 glacier environments, we designed and implemented a FCM that addresses the challenging problem of autonomously assessing the Glacier Lake Outburst Flow Potential and Impound Water Upstream Flow Potential. The FCM is constructed using what is currently our understanding of how glacier lake outbursts occur, whereas the causal connection between concepts is defined to capture the expertise of glacier scientists. The proposed graph contains 27 nodes and a network of connections that represent the causal link between concepts. To test the developed FCM, we defined three scenarios representing glacier lake environmental conditions that either occurred or that are likely to occur in such highly dynamic environments. For each case, the FCM has been initialized using observables extracted from hypothesized remote sensing imagery. The map, which converges to a fixed point for all of the test scenarios within 15 iterations, shows reasoning consistent with that of glacier experts. The FCM-based cognitive approach has the potential to be the AI core of real-time operational hazards assessment and detection systems.
This project, conducted by the United States Geological Survey (USGS), documents changes over time in the landscape of Glacier National Park, particularly the retreat of the park's glaciers. The project involves pairing historic photos from the park's archives with recent photos to illustrate how the landscape has changed. Users can view and download the photos in pairs with dates and a caption describing the scene and the changes that have taken place.
Bakke, Jostein; Røthe, Torgeir; van der Bilt, Willem; Paasche, Øyvind
Glaciers and snow are the very symbol of the Arctic, covering large parts of its terrestrial surface throughout the year. The cool temperatures that have allowed for the widespread coverage of glaciers are now trending towards a warmer climate, and with this gradual shift we observe a non-linear response in the cryosphere of which glaciers are a key component. This change is manifested in retreating fronts and an overall thinning. Because the typology of Arctic glaciers is rich and varied, the response pattern to the on-going warming is not unison. Instead we observe large spatial variations due to the critical balance between summer temperature and winter precipitation, but also other factors such as aspect, altitude, geographical location, debris cover and so forth. Even so, minor variations is superimposed on a larger trends which suggests that in a not so distant future, glaciers will probably be less abundant than what has been common for the last 100 years. In the context of the last 10 000 years it is evident that arctic glaciers have changed significantly and they have even been smaller than they are today, which was the case 9000 to 5000 years ago. On Svalbard, three glacier lake sediment records foretell of large past variations, indicating a more articulated sensitivity to climate change than what is commonly perceived for the Arctic cryosphere. Based on the lake sediment studies we will discuss Arctic glaciers sensitivity to decadal to millenium scale climate fluctuations and discuss possible forcing mechanims behind suitable for explaining what we see.
Gao, Hongkai; Hrachowitz, Markus; Savenije, Hubert
The glacier and snow melt water from mountainous area is an essential water resource in Northwest China, where the climate is arid. Therefore a hydrologic model including glacier and snow melt simulation is in an urgent need for water resources management and prediction under climate change in this region. In this study, the Urumqi No.1 Glacier catchment in Northwest China, with 51% area covered by glacier, was selected as the study site. An integrated daily hydrological model was developed to systematically simulate the hydrograph, runoff separation (glacier and non-glacier runoff), the glacier mass balance (GMB), the equilibrium line altitude (ELA), and the snow water equivalent (SWE). Only precipitation, temperature and sunshine hour data is required as forcing input. A combination method, which applies degree-day approach during dry periods and empirical energy balance formulation during wet seasons, was implemented to simulate snow and glacier melt. Detailed snow melt processes were included in the model, including the water holding capacity of snow pack, the liquid water refreezing process in snow pack, and the change of albedo with time. A traditional rainfall-runoff model (Xinanjiang) was applied to simulate the rainfall(snowmelt)-runoff process in non-glacierized area. Additionally, the influence of elevation on temperature and precipitation distribution, and the impact of different aspect on snow and glacier melting were considered. The model was validated, not only by long-term observed daily runoff data, but also by measured snow (SWE) and glacier data (GMB, ELA) of over 50 years. Furthermore, the calibrated model can be upscaled into a larger catchment, which further supports our proposed model and optimized parameter sets.
Sanders, J. W.; Cuffey, K. M.; MacGregor, K. R.; Kavanaugh, J. L.; Dow, C. F.
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.
Shijin Wang; Yuanqing He; Xiaodong Song
Alpine glaciers usually feature with best hydrothermal condition in mountain climate, and present beautiful glacier scenery,\\u000a various glacier landforms, rich biodiversity, and easier accessibility, compared with continental glaciers or ice sheets.\\u000a Nevertheless, Alpine glaciers are more sensitive to climate warming, and climate warming has seriously affected Alpine glaciers\\u000a and surrounding environment. The quality and attractiveness of Alpine glaciers to tourism
Yasunari, Teppei J.
The subject of climate change in the areas of the Tibetan Plateau (TP) and the Himalayas has taken on increasing importance because of available water resources from their mountain glaciers. Many of these glaciers over the region have been retreating, while some are advancing and stable. Other studies report that some glaciers in the Himalayas show acceleration on their shrinkage. However, the causes of the glacier meltings are still difficult to grasp because of the complexity of climatic change and its influence on glacier issues. However, it is vital that we pursue further study to enable the future prediction on glacier changes.
Rabatel, Antoine; Jomelli, Vincent; Naveau, Philippe; Francou, Bernard; Grancher, Delphine
Fluctuations of the Charquini glaciers (Cordillera Real, Bolivia) have been reconstructed for the Little Ice Age (LIA) from a set of 10 moraines extending below the present glacier termini. A lichenometric method using the Rhizocarpon geographicum was used to date the moraines and reconstruct the main glacier fluctuations over the period. The maximum glacier extent occurred in the second half of the 17th century, followed by nearly continuous retreat with three interruptions during the 18th and the 19th centuries, marked by stabilisation or minor advances. Results obtained in the Charquini area are first compared with other dating performed in the Peruvian Cordillera Blanca and then with the fluctuations of documented glaciers in the Northern Hemisphere. Glacier fluctuations along the tropical Andes (Bolivia and Peru) were in phase during the LIA and the solar forcing appears to be important during the period of glacier advance. Compared with the Northern Hemisphere mid-latitudes, the major advance observed on these glaciers during the first half of the 19th century is not present in the tropical Andes. This discrepancy may be due to regional scale climate variations. To cite this article: A. Rabatel et al., C. R. Geoscience 337 (2005).
Martin Demidow; Derek Heathfield; Ahmed Mumeni; Blair Underhill; Sam Ward
Lichenometry and dendroglaciology were two methods used to date the Asulkan Glacier spill-over zone in Glacier National Park, B.C. Thalli measurements of Rhizocarpon geographicum were taken at three different moraines for detailed analysis using statistics and growth curves. Dendroglaciology measurements were taken at similar sites to the lichen measurements. These consisted of tree core samples, whorl counts and basal disks
Bruce Raup; Adina Racoviteanu; Siri Jodha Singh Khalsa; Christopher Helm; Richard Armstrong; Yves Arnaud
The Global Land Ice Measurement from Space (GLIMS) project is a cooperative effort of over sixty institutions world-wide with the goal of inventorying a majority of the world's estimated 160000 glaciers. Each institution (called a Regional Center, or RC) oversees the analysis of satellite imagery for a particular region containing glacier ice. Data received by the GLIMS team at the
L. R. Mayo; R. S. March
Measurements at Wolverine Glacier, Alaska, from 1968 to 1988 indicate unsteady increases of air temperature and precipitation since the early 1970s. These increases were due almost entirely to changes in winter. Variations in annual temperature and precipitation at Wolverine Glacier and at Seward, a nearby climatological station at sea level, correlate positively with global temperature variations and are in general
Pritchard, M. E.; Willis, M. J.; Melkonian, A. K.; Golos, E. M.; Stewart, A.; Ornelas, G.; Ramage, J. M.
We provide new surveys of ice speeds and surface elevation changes for ~40,000 km2 of glaciers and ice caps at the Novaya Zemlya (NovZ) and Severnaya Zemlya (SevZ) Archipelagoes in the Russian High Arctic. The contribution to sea level rise from this ice is expected to increase as the region continues to warm at above average rates. We derive ice speeds using pixel-tracking on radar and optical imagery, with additional information from InSAR. Ice speeds have generally increased at outlet glaciers compared to those measured using interferometry from the mid-1990s'. The most pronounced acceleration is at Inostrantseva Glacier, one of the northernmost glaciers draining into the Barents Sea on NovZ. Thinning rates over the last few decades are derived by regressing stacked elevations from multiple Digital Elevations Models (DEMs) sourced from ASTER and Worldview stereo-imagery and cartographically derived DEMs. DEMs are calibrated and co-registered using ICESat returns over bedrock. On NovZ thinning of between 60 and 100 meters since the 1950s' is common. Similar rates between the late 1980s' and the present are seen at SevZ. We examine in detail the response of the outlet glaciers of the Karpinsky and Russanov Ice Caps on SevZ to the rapid collapse of the Matusevich Ice Shelf in the late summer of 2012. We do not see a dynamic thinning response at the largest feeder glaciers. This may be due to the slow response of the cold polar glaciers to changing boundary conditions, or the glaciers may be grounded well above sea level. Speed increases in the interior are difficult to assess with optical imagery as there are few trackable features. We therefore use pixel tracking on Terra SARX acquisitions before and after the collapse of the ice shelf to compute rates of flow inland, at slow moving ice. Interior ice flow has not accelerated in response to the collapse of the ice shelf but interior rates at the Karpinsky Ice Cap have increased by about 50% on the largest outlet glacier compared to rates found using ERS data in the mid-90s. Speeds have at least doubled at some of the smaller glaciers that feed the Matusevich from the south. We investigate the causes of acceleration at both archipelagoes by comparing sea surface temperatures and passive microwave observations of the timing and duration of ice surface melting.
Benson, C. S.
The concept of glacier facies developed as a result of physical measurements made in Greenland on repeated traverses that went inland from the west coast at two latitudes (77 N and 70 N) and north to south along the crest of the ice sheet. Snow pits and shallow cores showed discontinuities in physical characteristics that defined the facies boundaries. Some refinement have resulted from research in Antarctica and on Alaskan mountain glaciers. Thirty years after the facies were defined, based on field measurements, it was found that radar data (SAR) from satellites show the boundary between the percolation and dry snow facies in Greenland. They also show the percolation facies of the Greenland ice sheet to be the brightest radar reflector on earth. The dry snow facies is rare except on the major ice sheets (Greenland and Antarctica), but it is present on mountains that exceed 4000 m in Alaska and the Yukon. In particular, Mt. Wrangell, Alaska was selected for continued study of glacier facies because it has a large and accessible area above 4000 m. Mt. Wrangell has proven to have the full spectrum of glacier facies, and these can be seen on the SAR map of Alaska. Refinements in the definition of the lower end of the wet snow facies, to deal with a slush zone and a superimposed ice zone, resulted from Fritz Mueller's research on Axel Heiberg Island and from studies on the McCall Glacier of Alaska. Minor refinements in defining the dry snow facies resulted from comparing Antarctica and Greenland in places where mean annual temperature and accumulation rates were essentially equal. The glacier facies concept also provides a way of comparing the two polar regions and of speculating on the glacier facies that existed on the Pleistocene continental ice sheets.
Trabant, D. C.; March, R. S.; Cox, L. H.; Josberger, E. G.
Small but hydrologically significant shifts in climate have affected the rates of glacier volume change at the three U.S. Geological Survey Benchmark glaciers. Rate changes are detected as inflections in the cumulative conventional and reference-surface mass-balances of Wolverine and Gulkana Glaciers in Alaska and South Cascade Glacier in Washington. The cumulative mass balances are robust and have recently been corroborated by geodetic determinations of glacier volume change. Furthermore, the four-decade length of record is unique for the western hemisphere. Balance trends at South Cascade Glacier in Washington are generally in the opposite sense compared with Wolverine Glacier in Alaska; NCEP correlation of winter balance with local winter temperatures is positive at 0.59 for Wolverine and -0.64 for South Cascade Glacier. At Wolverine Glacier, the negative trend of cumulative mass balances, since measurements began in 1965, was replaced by a growth trend \\(positive mass balances\\) during the late 1970s and 1980s. The positive mass-balance trend was driven by increased precipitation during the 1976/77 to 1989 period. At Gulkana Glacier, the cumulative mass-balance trend has been negative throughout its measurement history, but with rate-change inflection points that coincide with the interdecadal climate-regime shifts in the North Pacific indices. At South Cascade Glacier, the mass-loss trend, observed since measurements began in 1953, was replaced by a positive trend between 1970 and 1976 then became strongly and continuously negative until 1997 when the rate of loss generally decreased. Since 1989, the trends of the glaciers in Alaska have also been strongly negative. These loss rates are the highest rates in the entire record. The strongly negative trends during the 1990s agree with climate studies that suggest that the period since the 1989 regime shift has been unusual. Volume response time and reference surface balance are the current suggested methods for analyzing the response of glaciers to climate. Volume response times are relatively simple to determine and can be used to evaluate the temporal, areal, and volumetric affects of a climate change. However, the quasi-decadal period between the recent climate-regime shifts is several times less than the theoretical volume readjustment response times for the benchmark glaciers. If hydrologically significant climate shifts recur at quasi-decadal intervals and if most glaciers' volume-response times are several times longer \\(true for all but a few small, steep glaciers\\), most medium and large glaciers are responding to the current climate and a fading series of regime shifts which, themselves, vary in magnitude. This confused history of driver trends prevent conventional balances from being simply correlated with climate. Reference-surface balances remove the dynamic response of glaciers from the balance trend by holding the surface area distribution constant. This effectively makes the reference surface balances directly correlated with the current climatic forcing. The challenging problem of predicting how a glacier will respond to real changes in climate may require a combination of the volume response time and reference surface mass balances applied to a long time-series of measured values that contain hydrologically significant variations.
The Columbia Glacier in Alaska is one of many vanishing around the world. Glacier retreat is one of the most direct and understandable effects of climate change. The consequences of the decline in ...
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
Several studies on Himalayan glaciers 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 Glacier (15.7 square km, 9 km long, 6263-4050 m a.s.l.) located in Lahaul and Spiti Valley, Himachal Pradesh, India. This glacier lies in the monsoon-arid transition zone (western Himalaya) and is a representative glacier 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 glacier-wide mass balance of Chhota Shigri glacier. During the period 2002-2013, the glacier experienced a negative glacier-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 glacier-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 glacier-wide mass balance, ELA and AAR data between 2002 and 2013. The winter glacier-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 glacier-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 2002-2013 observation period. The negative gradients can be explained by the thickness of debris cover that increases with decrease in altitude, thus protecting the glacier more efficiently at lower altitudes. Mass balance is strongly dependent on debris cover, exposure (solar radiation) and the shading effect of surrounding steep slopes.
This video contains a mix of live action video, stills, and computer animations of the Glacier Bay National Park in Glacier Bay, Alaska. Satellite mapping and imagery are used to show changes in the Glacier Bay area over a period of several years. Specific image processing techniques are discussed in relation to determining the evolution of glacier terminus points and in obtaining elevation data and how it is used to create fly-by visualizations of the area.
Rastogi, G.; Ajai
Surface energy balance of a glacier governs the physical processes taking place at the surface-atmosphere interface and connects ice ablation/accumulation to climate variability. To understand the response of Himalayan glaciers to climatic variability, a study was taken to formulate energy balance equation on two of the Indian Himalayan glaciers, one each from Indus and Ganga basins, which have different climatic and physiographic conditions. Study was carried out over Gangotri glacier (Ganga basin) and Chhota Shigri(CS) glacier from Chandra sub-basin (Indus basin). Gangotri glacier is one of the largest glaciers in the central Himalaya located in Uttarkashi District, Uttarakhand, India. Chhota Shigri glacier of Chandra sub-basin lies in Lahaul and Spiti valley of Himachal Pradesh. Energy balance components have been computed using inputs derived from satellite data, AWS (Automatic Weather Station) data and field measurements. Different components of energy balance computed are net radiation (includes net shortwave and net longwave radiation), sensible heat flux and latent heat flux. In this study comparison has been made for each of the above energy balance components as well as total energy for the above glaciers for the months of November and December, 2011. It is observed that net radiation in Gangotri glacier is higher by approximately 43 % in comparison to Chhota Shigri glacier; Sensible heat flux is lesser by 77 %; Latent heat flux is higher by 66 % in the month of November 2011. Comparison in the month of December shows that net radiation in Gangotri glacier is higher by approximately 22 % from Chhota Shigri glacier; Sensible heat flux is lesser by 90 %; Latent heat flux is higher by 3 %.Total energy received at the glacier surface and contributes for melting is estimated to be around 32 % higher in Gangotri than Chhota Shigri glacier in November, 2011 and 1.25 % higher in December, 2011. The overall results contribute towards higher melting rate in November and December, 2011 in Gangotri than Chhota Shigri glacier.
van Beusekom, A. E.; March, R. S.; O'Neel, S.
The USGS monitors long-term glacier mass balance at three benchmark glaciers in different climate regimes. The coastal and continental glaciers are represented by Wolverine and Gulkana Glaciers in Alaska, respectively. Field measurements began in 1966 and continue. We have reanalyzed the published balance time series with more modern methods and recomputed reference surface and conventional balances. Addition of the most recent data shows a continuing trend of mass loss. We compare the updated balances to the previously accepted balances and discuss differences. Not all balance quantities can be determined from the field measurements. For surface processes, we model missing information with an improved degree-day model. Degree-day models predict ablation from the sum of daily mean temperatures and an empirical degree-day factor. We modernize the traditional degree-day model as well as derive new degree-day factors in an effort to closer match the balance time series and thus better predict the future state of the benchmark glaciers. For subsurface processes, we model the refreezing of meltwater for internal accumulation. We examine the sensitivity of the balance time series to the subsurface process of internal accumulation, with the goal of determining the best way to include internal accumulation into balance estimates.
Thompson, David E.
There are procedures and methods for verification of coding algebra and for validations of models and calculations that are in use in the aerospace computational fluid dynamics (CFD) community. These methods would be efficacious if used by the glacier dynamics modelling community. This paper is a presentation of some of those methods, and how they might be applied to uncertainty management supporting code verification and model validation for glacier dynamics. The similarities and differences between their use in CFD analysis and the proposed application of these methods to glacier modelling are discussed. After establishing sources of uncertainty and methods for code verification, the paper looks at a representative sampling of verification and validation efforts that are underway in the glacier modelling community, and establishes a context for these within overall solution quality assessment. Finally, an information architecture and interactive interface is introduced and advocated. This Integrated Cryospheric Exploration (ICE) Environment is proposed for exploring and managing sources of uncertainty in glacier modelling codes and methods, and for supporting scientific numerical exploration and verification. The details and functionality of this Environment are described based on modifications of a system already developed for CFD modelling and analysis.
Moon, Twila; Joughin, Ian; Smith, Ben; van den Broeke, Michiel R; van de Berg, Willem Jan; Noël, Brice; Usher, Mika
Predicting Greenland Ice Sheet mass loss due to ice dynamics requires a complete understanding of spatiotemporal velocity fluctuations and related control mechanisms. We present a 5?year record of seasonal velocity measurements for 55 marine-terminating glaciers distributed around the ice sheet margin, along with ice-front position and runoff data sets for each glacier. Among glaciers with substantial speed variations, we find three distinct seasonal velocity patterns. One pattern indicates relatively high glacier sensitivity to ice-front position. The other two patterns are more prevalent and appear to be meltwater controlled. These patterns reveal differences in which some subglacial systems likely transition seasonally from inefficient, distributed hydrologic networks to efficient, channelized drainage, while others do not. The difference may be determined by meltwater availability, which in some regions may be influenced by perennial firn aquifers. Our results highlight the need to understand subglacial meltwater availability on an ice sheet-wide scale to predict future dynamic changes. Key Points First multi-region seasonal velocity measurements show regional differences Seasonal velocity fluctuations on most glaciers appear meltwater controlled Seasonal development of efficient subglacial drainage geographically divided PMID:25821275
Nettles, M.; Larsen, T. B.; Elosegui, P.; Hamilton, Gordon S.; Stearns, Leigh; Ahlstrom, A. P.; Davis, J. L.; Anderson, M. L.; de Juan, J.; Khan, S. A.; Stenseng, L.; Ekstrom, G.; Forsberg, R.
with teleseismically detected glacial earthquakes and major iceberg calving events. No coseismic offset in the position of the glacier surface is observed; instead, modest tsunamis associated with the glacial earthquakes implicate glacier calving in the seismogenic...
Hall, M.H.P.; Fagre, D.B.
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.
Fountain, Andrew G.
WATER FLOW THROUGH TEMPERATE GLACIERS Andrew G. Fountain1 Department of Geology Portland State, Washington Abstract. Understanding water movement through a glacier is fundamental to several critical issues glacierized drainage basins. To this end we have synthesized a conceptual model of water movement through
Sorg, Annina; Kääb, Andreas; Roesch, Andrea; Bigler, Christof; Stoffel, Markus
While the responses of Tien Shan glaciers--and glaciers elsewhere--to climatic changes are becoming increasingly well understood, this is less the case for permafrost in general and for rock glaciers in particular. We use a novel approach to describe the climate sensitivity of rock glaciers and to reconstruct periods of high and low rock glacier activity in the Tien Shan since 1895. Using more than 1500 growth anomalies from 280 trees growing on rock glacier bodies, repeat aerial photography from Soviet archives and high-resolution satellite imagery, we present here the world's longest record of rock glacier movements. We also demonstrate that the rock glaciers exhibit synchronous periods of activity at decadal timescales. Despite the complex energy-balance processes on rock glaciers, periods of enhanced activity coincide with warm summers, and the annual mass balance of Tuyuksu glacier fluctuates asynchronously with rock glacier activity. At multi-decadal timescales, however, the investigated rock glaciers exhibit site-specific trends reflecting different stages of inactivation, seemingly in response to the strong increase in air temperature since the 1970s. PMID:25657095
2003-01-01This 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 blocks of ice are caught up in the deposits and then melt, locally collapsing the deposit. The combination of Landsat imagery and SRTM elevation data used in this stereoscopic display is very effective in visualizing these and other features of this terrain. The stereoscopic effect of this anaglyph was created by registering a Landsat image to the SRTM elevation model and then generating two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter. Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data matches the 30-meter (98-foot) resolution of most Landsat images and substantially helps in analyzing the large and growing Landsat image archive. Elevation data used in this image were acquired by the Shuttle Radar Topography Mission aboard the Space Shuttle Endeavour, launched on February 11, 2000. The mission used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar that flew twice on the Space Shuttle Endeavour in 1994. The Shuttle Radar Topography Mission was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between NASA, the National Imagery and Mapping Agency of the U.S. Department of Defense, and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC. Size: 55 x 55 kilometers (34 x 34 miles) Location: 60 deg N latitude, 140 deg W longitude Orientation: North at top Image Data: Landsat Thematic Mapper visible and infrared band mix Original Data Resolution: SRTM 1 arcsecond (30 mete
Raper, S. C. B.; Braithwaite, R. J.
Glacier volume response time is a measure of the time taken for a glacier to adjust its geometry to a climate change. It is currently believed that the volume response time is given approximately by the ratio of glacier thickness to ablation at the glacier terminus. We propose a new conceptual model of glacier hypsometry (area-altitude relation) and derive the volume response time where climatic and topographic parameters are separated. The former is expressed by mass balance gradients which we derive from glacier-climate modelling and the latter are quantified with data from the World Glacier Inventory. Aside from the well-known scaling relation between glacier volume and area, we establish a new scaling relation between glacier altitude range and area, and evaluate it for seven regions. The presence of this scaling parameter in our response time formula accounts for the mass balance elevation feedback and leads to longer response times than given by the simple ratio of glacier thickness to ablation. Volume response times range from decades to thousands of years for glaciers in maritime (wet-warm) and continental (dry-cold) climates, respectively. The combined effect of volume-area and altitude-area scaling relations is such that volume response time can increase with glacier area (Axel Heiberg Island and Svalbard), hardly change (Northern Scandinavia, Southern Norway and the Alps) or even get smaller (The Caucasus and New Zealand).
Raper, S. C. B.; Braithwaite, R. J.
Glacier volume response time is a measure of the time taken for a glacier to adjust its geometry to a climate change. It has been previously proposed that the volume response time is given approximately by the ratio of glacier thickness to ablation at the glacier terminus. We propose a new conceptual model of glacier hypsometry (area-altitude relation) and derive the volume response time where climatic and topographic parameters are separated. The former is expressed by mass balance gradients which we derive from glacier-climate modelling and the latter are quantified with data from the World Glacier Inventory. Aside from the well-known scaling relation between glacier volume and area, we establish a new scaling relation between glacier altitude range and area, and evaluate it for seven regions. The presence of this scaling parameter in our response time formula accounts for the mass balance elevation feedback and leads to longer response times than given by the simple ratio of glacier thickness to ablation at the terminus. Volume response times range from decades to thousands of years for glaciers in maritime (wet-warm) and continental (dry-cold) climates respectively. The combined effect of volume-area and altitude-area scaling relations is such that volume response time can increase with glacier area (Axel Heiberg Island and Svalbard), hardly change (Northern Scandinavia, Southern Norway and the Alps) or even get smaller (The Caucasus and New Zealand).
Stefan Winkler; Hallgeir Elvehøy; Atle Nesje
The steep outlet glaciers of Jostedalsbreen, western Norway, are good examples of sensitively reacting maritime mountain glaciers. Their changes in length, frontal position and lower tongue's morphology during the past 20 years have been well documented. At first they experienced a strong frontal advance. After AD 2000 glacier behaviour was dominated by a strong frontal retreat, in some cases causing
This news article describes how mountain lakes in Nepal and Bhutan have become so overfilled by water from melting glaciers that they are in danger of overflowing. Scientists from the United Nations Environment Program (UNEP), along with remote-sensing experts from the International Center for Integrated Mountain Development (ICIMOD), predict that in the next half decade or so, the Himalayas could experience intense flooding as mountain lakes overflow with water from glaciers and snowfields which are melting as a result of gradually rising global temperatures.
Warren, C.R.; Glasser, N.F. (Univ. of Edinburgh, Scotland (United Kingdom))
A unique geographical configuration of glaciers exists in the Narsarsuaq district of South Greenland. Two large outlet glaciers divide into seven distributaries, such that each glacier system has land-terminating, tidewater-calving, and fresh-water-calving termini. Despite a similar climatic regime, these seven glaciers have exhibited strongly contrasting terminal behavior in historical time, as shown by historical records, aerial photographs, and fieldwork in 1989. The behavior of the calving glaciers cannot be accounted for with reference solely to climatic parameters. The combination of iceberg calving dynamics and topographic control has partially decoupled them from climatic forcing such that their oscillations relate more closely to glaciodynamic than glacioclimatic factors.
This hands-on activity demonstrates the abrasive power of glaciers carrying rocks and sand. Its purpose is to illustrate the concept that glaciers change the Earth's surface through the processes of erosion and deposition. Students construct model glaciers by freezing water with sand and pebbles at the bottom to represent the rock fragments carried by a real glacier. They then rub their 'glacier' across rocks of varying hardness to see what happens. Afterwards, they place the ice where it can melt and observe what happens to the sand and pebbles trapped in it. A materials list, procedures, and background information are supplied.
Stephan Harrison; Ann V. Rowan; Neil F. Glasser; Jasper Knight; Mitchell A. Plummer; Stephanie C. Mills
It is widely believed that the last glaciers in the British Isles disappeared at the end of the Younger Dryas stadial (12.9–11.7 cal. kyr BP). Here, we use a glacier–climate model driven by data from local weather stations to show for the first time that glaciers developed during the Little Ice Age (LIA) in the Cairngorm Mountains. Our model is forced from contemporary conditions by a realistic difference in mean annual air temperature of -1.5 degrees C and an increase in annual precipitation of 10%, and confirmed by sensitivity analyses. These results are supported by the presence of small boulder moraines well within Younger Dryas ice limits, and by a dating programme on a moraine in one cirque. As a result, we argue that the last glaciers in the Cairngorm Mountains (and perhaps elsewhere in upland Britain) existed in the LIA within the last few hundred years, rather than during the Younger Dryas.
Brugman, Melinda M.; Post, Austin
The cataclysmic eruption of Mount St. Helens May 18, 1980, removed 2.9 km2 (about 0.13 km3) of glacier snow and ice including a large part of Shoestring, Forsyth, Wishbone, Ape, Nelson, and all of Loowit and Leschi Glaciers. Minor eruptions and bulging of the volcano from March 27 to May 17 shattered glaciers which were on the deforming rock and deposited ash on other glaciers. Thick ash layers persisted after the May 18 eruption through the summer on most of the remaining snow and ice, and protected winter snow from melting on Swift and Dryer Glaciers. Melting and recrystalization of snow and ice surviving on Mount St. Helens could cause and lubricate mudflows and generate outburst floods. Study of glaciers that remain on this active volcano may assist in recognizing potential hazards on other volcanoes and lead to new contributions to knowledge of the transient response of glaciers to changes in mass balance or geometry.
Cohen, Denis; Haeberli, Wilfried; Fischer, Urs H.; Machguth, Horst
Climate proxies based on pollen records, macrofossil assemblages, or speleotherms indicate cold and dry conditions during the Last Glacial Maximum in Northern-Central Europe. A high-resolution full-Stokes three-dimensional thermo-mechanical model of the Rhine glacier, Swiss Alps, at the Last Glacial Maximum indeed indicates extremely dry conditions with mass balance ablation gradients as low as 0.01 m/a/100m. This balance gradient is necessary to match modeled LGM extent with observations of LGM moraines in the Swiss plateau. Extremely low balance gradients could be due to (1) extreme temperature inversion, (2) increasing shadow towards the ice margin due to termination of glacier in deep valleys or gorges, (3) debris cover of increasing thickness towards the margin, or (4) accumulation of wind-blown snow at the glacier margin. There is no evidence for (2) or (3) for the margin of the Rhine glacier which terminated in a wide piedmont lobe. The other two hypotheses have not been tested for LGM conditions at the margin of the Rhine glacier. Higher ice temperature (which reduces ice viscosity) and more sliding (higher ratio of sliding to surface velocity) would favor an extended glacier margin at a higher ablation gradient but these effects are already included in the numerical model. These results suggest a discrepancy between observations and present knowledge of climate and ice sheet flow which cannot be easily explained and need further investigation.
Hughes, P. D.; Woodward, J. C.; Gibbard, P. L.
Evidence for Late Pleistocene glaciers and rock glaciers in the Pindus Mountains, Greece, is used to reconstruct palaeoclimate for this part of the Mediterranean during the last cold stage (Tymphian/ Würmian). Mean annual precipitation was c. 2300 ± 200 mm and the mean summer temperature (June/July/August) was c. 4.9 °C at 2174 m a.s.l., the equilibrium line altitude of the former glaciers, at the last local glacier maximum. The glacier-climate relationship in the northern Pindus Mountains during the local glacier maximum of the Tymphian Stage closely resembled that found today at the equilibrium line altitude of Norwegian glaciers. The local glacier maximum on Mount Tymphi is likely to have preceded both the most severe phase of climate indicated in the pollen record at nearby Ioannina and also the global last glacial maximum. Major stadials, including the most severe phase of the last cold stage, were characterised by cold sea surfaces temperatures, which inhibited atmospheric moisture supply creating unfavourable conditions for glacier formation. Such stadial conditions are likely to have favoured periglacial conditions and the formation of features such as rock glaciers. Conversely, warm summer temperatures during major interstadials would have promoted glacier ablation, offsetting increased precipitation enabled by warmer sea surface temperatures. Thus, the most favourable conditions for glacier formation would have occurred during intermediate conditions between major stadials and interstadials. It is clear that former glacier behaviour in the mountains of this region is best understood with reference to temporally dynamic glacier-climate models, which take into account millennial-scale changes in both precipitation and temperature.
Josberger, Edward G.; Bidlake, William R.
The long-term USGS measurement and reporting of mass balance at South Cascade Glacier 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 glacier 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 "glacier 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 glacier. The 2006 and 2007 winter balances of South Cascade Glacier, 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 Glacier in Washington state. Presented at the American Geophysical Union Fall Meeting 2010.
Herzfeld, U. C.; McDonald, B.; Trantow, T.; Hale, G.; Stachura, M.; Weltman, A.; Sears, T.
Understanding fast glacier flow and glacial accelerations is important for understanding changes in the cryosphere and ultimately in sea level. Surge-type glaciers are one of four types of fast-flowing glaciers --- the other three being continuously fast-flowing glaciers, fjord glaciers and ice streams --- and the one that has seen the least amount of research. The Bering-Bagley Glacier System, Alaska, the largest glacier 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 glacier system (as opposed to a small glacier 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 Glacier during Surge, July 2012 Airborne laser altimeter profile across major rift in central Bering Glacier, Sept 2011
Panoramic photographic mosaic of several glaciers on the northern slope of Gora Elbrus, a volcanic massif in the Central Caucasus Mountains. The photographic survey was done by N. Nikulin in 1957 during the International Geophysical Year. Photograph courtesy of V.M. Kotlyakov, Russian Academy of Sci...
Ashley, Gail Mowry
Discusses the presence and dynamics of continental glaciers in the domination of the physical processes of erosion and deposition in the mid-latitudes during the Pleistocene period. Describes the use of a sedimentary facies model as a guide to recognizing ancient temperate continental glacial deposits. (TW)
Asulkan Valley Avalanche Track, Glacier National Park Penelope Simpson, Jessica Paramio Maciej with the use of these trails ranges from bear encounters to triggering an avalanche. As in many mountainous regions, a high avalanche risk exists in the park during the winter due to the steep, rugged terrain
Hintz, R. S.; Landis, C.
Few opportunities exist for early elementary students to do inquiry or guided inquiry into topics dealing with climate change and glaciers. "Flubber" offers a simulation for the movement of glacial ice. It is inexpensive to make, stores well, and can be re-used. Students of all ages enjoy watching, measuring, and thinking about flubber and what it represents. As the interest in ice sheets continues to build, activities that both help to illustrate how glaciers move and provide a launch pad for student-driven investigations need to be available to teachers. With support from the National Science Foundation's Science and Technology Center for the Remote Sensing of Ice Sheets (CReSIS), a set of activities has been developed to provide opportunities for early elementary students to develop inquiry skills within the standards for early elementary grades bands in the National Science Education Standards. Lesson plans, instructions for making and using "Flubber", student worksheets, teacher guides with glacier and climate change information, and a chart of the National Science Education Standards applicable to the activities are available to elementary teachers wishing to introduce their students to glaciers and climate change.
K. K. Falkner; H. L. Johnson; H. Melling; A. Muenchow; R. M. Samelson
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
Hynek, Bernhard; Hillerup Larsen, Signe; Binder, Daniel; Weyss, Gernot; Citterio, Michele; Schöner, Wolfgang; Ahlstrøm, Andreas Peter
Due to the scarceness of glacier mass balance measurements from glaciers and local ice caps in East Greenland and the strong impact that local glaciers and ice caps outside the Ice Sheet are expected to exert on sea level rise in the present century, in 2007 and 2008 two glaciological monitoring programmes of peripheral Greenlandic glaciers started to operate near the Zackenberg Research Station in NE Greenland (74° N, 21° W). Freya (Fröya) Glacier is a 6 km long valley glacier situated on Clavering Island 10 km southeast of the Zackenberg research station with a surface area of 5.3 km2 (2013), reaching from 1305 m to 273 m a.s.l. The glacier is mainly oriented to NW and surrounded by high mountain ridges on both sides. A.P. Olsen Ice Cap is a 295 km2 peripheral ice cap located 35 km northeast of Zackenberg. The mass balance monitoring network is situated on the SE outlet glacier reaching from 1425 m to 525 m which drains into the hydrological basin of Zackenberg. This outlet glacier dams a lake which caused several glacial outburst floods within the period of investigation. The two studied glaciers are very close to each other (35 km), but they are complementary in many ways. Apart from the difference in size, which requires different monitoring strategies, Freya Glacier is nearer to the coast and therefore exposed to a more maritime climate with higher winter accumulation. The different area-altitude distribution of both glaciers is one of the main reason for the significantly more positive mean specific mass balance of A.P. Olsen Ice Cap compared to Freya Glacier. In this talk we present the glaciological monitoring on both glaciers and the main results of the first seven years of data.
Glacier inventories are used for many applications in glaciology, however, their manual compilation is time-consuming. Here, we present two new algorithms for the automatic compilation of glacier inventories. The first approach is based on hydrological modeling tools and separates glacier complexes into individual glaciers, requiring a digital elevation model (DEM) and glacier complex outlines as input. Its application to >60,000 km2 of ice in Alaska (˜98% success rate) and southern Arctic Canada (˜97% success rate) indicates the method is robust if DEMs and glacier complex outlines of good quality are available. The second algorithm relies on glacier outlines and a DEM and derives centerlines in a three-step 'cost grid -- least cost route' procedure. First, termini and heads are determined for every glacier. Second, centerlines are derived by determining the least cost route on a previously determined cost grid. Third, the centerlines are split into branches, followed by the attribution of a branch order. Application to >21,000 Alaska glaciers shows that ˜5.5% of the glacier heads and ˜3.5% of the termini require manual correction. With corrected heads and termini, ˜1.5% of the actual derived centerlines need edits. Comparison with alternative approaches reveals that the centerlines vary significantly depending on the algorithm used.
Oneel, S.; Hood, E. W.; Arendt, A. A.; Sass, L. C.; March, R. S.
We examine long-term streamflow and mass balance data from two Alaskan glaciers located in climatically distinct basins: Gulkana Glacier, a continental glacier located in the Alaska Range, and Wolverine Glacier, a maritime glacier located in the Kenai Mountains. Both glaciers lost mass, primarily as a result of summer warming, and both basins exhibit increasing streamflow over the 1966-2011 study interval. We estimated total glacier runoff via summer mass balance, and separated the fraction related to annual mass imbalances. In both climates, the fraction of streamflow related to annual mass balance averages less than 20%, substantially smaller than the fraction related to total summer mass loss (>50%), which occurs even in years of glacier growth. The streamflow fraction related to changes in annual mass balance has increased only in the continental environment. In the maritime climate, where deep winter snowpacks and frequent rain events drive consistently high runoff, the magnitude of this streamflow fraction is small and highly variable, precluding detection of any existing trend. Changes in streamflow related to annual balance are often masked by interannual variability of maritime glacier mass balance, such that predicted scenarios of continued glacier recession are more likely to impact the quality and timing of runoff than the total basin water yield.
Rupper, S.; Schaefer, J. M.; Burgener, L. K.; Maurer, J.; Smith, R.; Cook, E.; Putnam, A. E.; Krusic, P.; Tsering, K.; Koenig, L.
Glacierized change in the Himalayas affects river-discharge, hydro-energy and agricultural production, and Glacial Lake Outburst Flood potential, but its quantification and extent of impacts remains highly uncertain. Here we present conservative, comprehensive and quantitative predictions for glacier area and meltwater flux changes in Bhutan, monsoonal Himalayas. In particular, we quantify the uncertainties associated with the glacier area and meltwater flux changes due to uncertainty in climate data, a critical problem for much of High Asia. Based on a suite of gridded climate data and a robust glacier melt model, our results show that glacier area and meltwater change projections can vary by an order of magnitude for different climate datasets. The most conservative results indicate that, even if climate were to remain at the present-day mean values (1980-2000), almost 10% of Bhutan's glacierized area would vanish and the meltwater flux would drop by as much as 30%. New mapping of glacierized area from 2000-2010 shows a significant change in glacierized area of 4-6%. Thus the conservative steady-state area changes predicted by the model are already being realized. Under the conservative scenario of an additional 1°C regional warming, glacier retreat is predicted to continue until about 25% of Bhutan's glacierized area will have disappeared and the annual meltwater flux, after an initial spike, would drop by as much as 65%.
Armstrong, R. L.; Racoviteanu, A.; Raup, B. H.; Khalsa, S. S.
The Global Land Ice Measurements from Space (GLIMS) initiative has built a database of glacier outlines and related attributes, derived primarily from satellite imagery, such as from ASTER and Landsat. Each snapshot of a glacier is from a specific time, and the database is designed to store multiple snapshots representative of different times. The database continues to expand both spatially and temporally: the number of glaciers represented, as well as the number of outlines from different times per glacier, are both increasing. As of August 2011, the database, located at NSIDC, contains outlines for approximately 95 000 glaciers, covering 290 000 km2. More datasets are expected soon, such as from GlobGlacier (e.g. all European Alps, western Greenland, Sweden, Baffin Island), and the Regional Centers for Svalbard, Argentina, Nepal, China, and others. Though the database does not yet cover the world's glaciers completely, approximately 670 glaciers have outlines from more than one time. This database increasingly enables analysis of global and regional glacier area and its distribution, glacier change, distribution of glaciers by different properties (e.g. morphology, debris-cover),and other yet-to-be imagined possibilities. In spite of steady progress, there remain some geographic areas that are not yet covered, including southernmost South America, Arctic Russia, the the periphery of most of Greenland and Antarctica. For applications such as sea level change studies that require complete global coverage of glaciers with at least moderate resolution, it is imperative that these gaps be filled soon. This will be addressed through adapting existing datasets to the GLIMS data model, using new satellite data and methods as they develop, and building analysis capacity worldwide to get more researchers involved in high accuracy glacier mapping.
Bolch, Tobias; Piezconka, Tino; Chen, Feng; Kang, Shichang; Buchroithner, Manfred
The larger glaciers at Mt. Everest are heavily covered with supra-glacial debris like many other glaciers in the Himalaya. Most glacier change studies concentrate on area change only. However, the melting of debris-covered glaciers is most recognisable through downwasting. Hence, multi-temporal DEM analysis is needed to study the reaction of these glaciers to climate change in detail. We generated a time series of DEMs based on stereo corona (years 1962 and 1972) aerial images (1984), ASTER (2001) and Cartosat-1 data (2007) for the southern side of Mt. Everest (investigated glaciers: Khumbu, Nuptse, Lhotse, Lhotse Nup, Lhotse Shar and Imja) and two DEMs for the northern side (Rongbuk Glacier) based on a topographic map (1974) and ASTER data (2003). IceSat GLAS data, topographic maps and field GPS measurements are used for validation. The Cartosat-1 DEM was chosen to be the master DEM due to the highest accuracy and the other DEMs were co-registered to it. The characteristics of the downwasting are similar for all investigated glaciers: The downwasting is pronounced in the upper part with thin debris-cover and less pronounced but still recognisable in the lower parts with thick debris-cover. The highest surface lowering at the southern side is found at the possible transition zone between the active and stagnant glacier parts. The average downwasting for the investigated Eastern Rongbuk Glacier seems to be little higher (0.81 ± 0.53 m/a) than the value for Khumbu Glacier (0.42 ± 0.21 m/a). Both the accumulation and ablation area of Khumbu Glacier showed a surface lowering. Volume loss is detected for all glaciers and investigated time periods.
Seroussi, H. L.; Morlighem, M.; Rignot, E. J.; Larour, E. Y.; Mouginot, J.; Khazendar, A.
Ice shelves play a major role in the stability of fast flowing ice streams in Antarctica, by exerting buttressing on inland ice and controlling the discharge of ice into the ocean. However, the mechanisms at work remain poorly understood and interactions between floating and grounded ice need to be better characterized in order to estimate the impact of climate change on the ice sheets. Thwaites glacier, in West Antarctica, features a small and heavily fractured ice shelf that provides limited back stress pressure on inland ice but is pinned on the eastern part on a prominent ridge. Thwaites glacier has maintained a consistently high velocity and negative mass balance for at least 20 years. Recent observations show a widening of its fast flowing area as well as a sustained acceleration since 2006 and a rapid retreat of its grounding line in the center of the glacier. The objective of this work is to characterize the dynamic response of Thwaites glacier to changes in its floating tongue on decadal to centennial time scales. To achieve this objective, we rely on high resolution ice flow modeling and grounding line dynamics using the Ice Sheet System Model (ISSM). We will focus on the complex interplay between the main floating tongue of Thwaites Glacier and its eastern, slow moving ice shelf, which is pinned down by an ice rumple. The speed of the eastern ice shelf is strongly affected by the coupling with the main floating ice tongue, which results in significant fluctuations in speed of the eastern ice shelf the formation of ice shelf cracks at the grounding line during acceleration phases. Our results show that ice rigidity at the junction between the eastern and western part of the shelf controls the dynamic regime of the ice shelf and suggest that Thwaites Glacier is likely to undergo substantial changes in the coming decades. This work was performed at the California Institute of Technology's Jet Propulsion Laboratory and the University of California Irvine under a contract with the National Aeronautics and Space Administration, Cryospheric Sciences and Modeling, Analysis and Prediction Programs
Thompson, L. G.; Permana, D.; Mosley-Thompson, E.; Davis, M. E.
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 basin. Here we examine recently recovered ice core records from glaciers near Puncak Jaya in Papua, Indonesia, which lie on the highest peak between the Himalayas and the South American Andes. These glaciers 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 (?18 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 Glacier 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 Jaya reinforce the hypothesis that large-scale tropical processes dominate recent tropical glacier retreat. The observed widespread melting of glaciers is consistent with model predictions of a vertical amplification of temperature, which is documented by increasing isotopic enrichment in ice cores from high elevation glaciers throughout the Tropics.
The motion of a glacier is largely determined by the nature of its bed. The basal morphology and its reaction to the overlying ice mass have been subject to much speculation, because the glacier bed is usually difficult to access, and good field data are sparse. In spring 1997 a commercial wireline drill rig was set up on Black Rapids Glacier, Alaska, to extract cores of basal ice, subglacial till, and underlying bedrock. One of the boreholes was equipped with three tiltmeters to monitor till deformation, and a piezometer to record pore water pressure. The surface velocity and ice deformation in a borehole were also measured. The drill successfully reached bedrock twice after penetrating a till layer, some 5 to 7 m in thickness, confirming an earlier seismic interpretation. The till consisted of a sandy matrix containing clasts up to boulder size. Bedrock and till lithology indicated that all the drill holes were located to the north of the Denali Fault, a major tectonic boundary along which the glacier flows. The mean annual surface velocity of the glacier was 60 ma-1 , of which 20 to 30 ma-1 were ice deformation, leaving 30 to 40 ma-1 of basal motion. The majority of this basal motion occurred at a depth of more than 2 m in the till, contradicting previously held ideas about till deformation. Basal motion could occur as sliding of till over the underlying bedrock, or on a series of shear layers within the till. This finding has implications for the interpretation of the geologic record of former ice sheets, for geomorphology, and for glacier dynamics. The effect of a thick till layer on ice flow and on quantities observable at the glacier surface was calculated. These include velocity changes on secular, seasonal, and shorter time scales. A mechanism for uplift events and dye tracing responses was suggested. An easy surface observation that could serve to clearly distinguish a glacier underlain by till from the more traditional view of a glacier underlain by bedrock could not be identified.
Kargel, Jeffrey; Leonard, Gregory; Regmi, Dhananjay; Haritashya, Umesh; Chand, Mohan; Pradhan, Suresh; Sapkota, Nawaraj; Byers, Alton; Joshi, Sharad; McKinney, Daene; Mool, Pradeep; Somos-Valenzuela, Marcelo; Huggel, Christian
Thulagi and Imja lakes are, according to ICIMOD, among Nepal's most dangerous glacier lakes, i.e., most likely to cause death and destruction in case of a glacier lake outburst flood (GLOF). Imja Lake and the associated Imja and Lhoste-Shar glaciers have been intensively studied; Thulagi Glacier and its lake are much less studied. Collectively, we have undertaken a series of increasingly thorough bathymetric and land surveys and satellite remote sensing analyses of Imja Lake and its glacier setting. We are analyzing several expeditions' data to build a detailed assessment of the glacier and lake to better establish the dynamical evolution of the system and its future GLOF potential. Our most recent, most complete bathymetric survey of Imja Lake has revealed a much greater volume (75,200,000 cubic meters) and maximum depth (149.8 m) than found before. Our analysis suggests that not all possible Imja GLOF scenarios would result in devastation. Some moraine melt-through or down-cutting mechanisms -- perhaps induced by extreme monsoon precipitation or an earthquake -- could generate outbursts lasting from 10,000-100,000 seconds ("slow GLOFs"), thus limiting peak flows and downstream damage. The potential damage from a slow GLOF from Imja Lake -- even if there is a large total volume -- is lessened by the relatively low peak discharge and because the major villages downstream from Imja Lake are situated just outside of and above a deep, broad outwash and debris-flow channel system. Imja and other glaciers in the area have built a large fan, now deeply trenched, which is able to accommodate the peak discharges of potential slow GLOFs, such that Dingboche and other villages would be spared. However, local geomorphology also bears evidence of "fast GLOFs," such as may be issued by a tsunami, which could be initiated by a large mass movement into Imja Lake and which might override and damage the end moraine in <100 seconds. Dingboche and other villages are vulnerable to such a "fast GLOF." Thulagi lake, on the other hand, exhibits a much larger hazard potential even from slow GLOFs simply because downstream developments -- particularly Tal village -- are established on the lowest part of the floodplain of an outwash channel system, and there is a lack of deep channel entrenchment. We will present some details of both glacier-lake systems from our recent bathymetric and satellite remote sensing of glacier behavior and the characteristics of downstream developments to explain why the two lakes pose different likelihoods of causing downstream devastation. Neither system is safe, but the hazards differ.
Elliott, J.; Melkonian, A. K.; Pritchard, M. E.
Glaciers 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 glaciers 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 glacier surface velocities in southeast Alaska produced through a pixel tracking technique using synthetic aperture radar data and high-resolution optical imagery. For glaciers with previous velocity estimates, we will compare the results and discuss possible implications for ice dynamics. We focus on Glacier Bay and the Stikine Icefield, which contain a number of fast-flowing tidewater glaciers 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 Glacier Bay, the highest surface velocities occur on the tidewater glaciers. La Perouse, the only Glacier Bay glacier to calve directly into the Pacific Ocean, has maximum velocities of 3.5 - 4 m/day. Johns Hopkins Glacier 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 Glacier 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 Glacier displays velocities of about 1 m/day while the eastern terminus has lower velocities of < 0.5 m/day. The lake terminating glaciers along the Pacific coast have overall lower surface velocities, but they display complex flow patterns. The Alsek Glacier 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 m/day while the terminus of the southern branch moves about 2 m/day. Grand Plateau Glacier also divides into two main branches, with a northern branch displaying peak velocities of 1.5 m/day and a southern branch flowing at a rate of 1 m/day. The Stikine Icefield contains a number of large tidewater glaciers showing maximum velocities near their termini. At the terminus of the South Sawyer Glacier, velocities reach a peak of about 2 m/day. Along the terminus of the Dawes Glacier, velocities reach 3.5 m/day. The Baird Glacier displays lower velocities of 1-1.5 m/day. LeConte Glacier has 2-3 m/day velocities in its upper regions with higher velocities near its terminus. In contrast to the pattern shown by the surrounding glaciers, the Great Glacier has a peak velocity of 2 m/day in the upper portion of the glacier and a velocity of only 0.5 m/day near its terminus.
Antoine Rabatel; Vincent Jomelli; Philippe Naveau; Bernard Francou; Delphine Grancher
Fluctuations of the Charquini glaciers (Cordillera Real, Bolivia) have been reconstructed for the Little Ice Age (LIA) from a set of 10 moraines extending below the present glacier termini. A lichenometric method using the Rhizocarpon geographicum was used to date the moraines and reconstruct the main glacier fluctuations over the period. The maximum glacier extent occurred in the second half
DeMorett, Joseph Lawrence
Creek Rock Glacier (Dutch Creek). 6. Stzeam issuing from the base of the California Rock Glacier. . . . . . , 7 The California Rock Glacier 8. Longitudinal profile of the California Rock Glacier study site. . . . . . 9. Cmss sectional profile... literature. A brief review of the rock glacier knowledge base is presented first, followed by an in-depth discussion of specific rock glacier studies pertinent to the thesis objectives. The physical setting in terms of geographic location, access, natural...
This atlas contains Landsat images, aerial photographs, selected maps, and other data, which provide a baseline look (from the mid-1970's) at glaciation in Canada, the conterminous United States, and Mexico. The Landsat false-color imagery includes ice fields, outlet glaciers, valley glaciers, and cirque glaciers, as well as ice caps. Ice features are grouped by location and a full description is available for each.
Badjukov, Dmitry D.; Brandstätter, Franz; Raitala, Jouko; Kurat, Gero
A large number of micrometeorites (MMs) was recovered from glacier deposits located at the north-eastern passive margin of the Novaya Zemlya glacier sheet. Melted, scoriaceous, and unmelted micrometeorites (UMMs) are present. Unmelted micrometeorites are dominated mostly by chondritic matter, but also a few achondritic MMs are present. Here we report the discovery of four UMMs that, according to their texture, mineralogy, and chemistry, are identified as basaltic breccias. Mineral chemistry and Fe/Mn ratios of two basaltic micrometeorites indicate a possible relationship with eucrites and/or mesosiderites, whereas two others seem to have parents, which appear not to be present in our meteorite collections. The basaltic breccia UMMs constitute 0.5% of the total population of the Novaya Zemlya MM suite. This content should be lowered to 0.25% because the Novaya Zemlya MM collection appears to be biased with carbonaceous UMMs being underrepresented.
TERC. Center for Earth and Space Science Education
In this interactive Earth science resource, students are first presented with six different photographs showcasing how glaciers can erode bedrock. Students are instructed to click on each labeled image to see an enlarged version of it. In the enlarged view, each photo is accompanied by a sentence or two that explains the glacial erosion shown. The images include features such as cirques, medial moraines, and striated bedrock. Copyright 2005 Eisenhower National Clearinghouse
The first segment of this radio broadcast discusses a recent expedition to the isolated Foja mountain range in western New Guinea, which has discovered several new species of birds, 20 new frog species, and four new butterfly species, as well as a rare bird which had not been seen for sixty years, and unusual plants. One of the explorers discusses the efforts to map the diversity of the island and the challenges in preserving such ecological treasures. This segment is 12 minutes and 21 seconds in length. The second segment consists of a conversation with researchers who travel the world documenting the retreat of mountain glaciers. Topics include efforts to build a global database of ice cores to document changes; a discussion of increased water flow from glaciers; the logistics of drilling ice cores at high altitude and moving them to a university lab; how annual snowfall is recorded in ice cores; and how retreating glaciers are exposing plants that were covered for six thousand years. This segment is 35 minutes and 20 seconds in length.
Harrison, W.D.; Raymond, C.F.; Echelmeyer, K.A.; Krimmel, R.M.
A simple approach to glacier dynamics is explored in which there is postulated to be a relationship between area and volume with three parameters: the time for area to respond to changes in volume, a thickness scale, and an area characterizing the condition of the initial state. This approach gives a good fit to the measurements of cumulative balance and area on South Cascade Glacier from 1970-97; the area time-scale is roughly 8 years, the thickness scale about 123 m, and the 1970 area roughly 4% larger than required for adjustment with volume. Combining this relationship with a version of mass continuity expressed in terms of area and volume produces a theory of glacier area and volume response to climate in which another time constant, the volume time-scale, appears. Area and volume both respond like a damped spring and mass system. The damping of the South Cascade response is approximately critical, and the volume time-scale is roughly 48 years, six times the area time-scale. The critically damped spring and mass analogy reproduces the time dependence predicted by the more complicated traditional theory of Nye.
Nick, F. M.; van der Veen, Cornelis J.; Oerlemans, J.
at the glacier terminus and presented the flotation model. In the flotation model the terminus position is defined as the point where the ice thickness exceeds the flotation thickness by an amount H0. If the glacier thins, the terminus will retreat to a point... where this condition is again satisfied. Vieli et al.  modified the flotation criterion and defined the thickness in excess of flotation H0 as a fraction of the flotation thickness. A recent modeling study by Nick and Oerlemans  compared both...
Alexander, David; Perrette, Mahé; Beckmann, Johanna
Basal melting of fast-flowing Greenland outlet glaciers and ice streams due to frictional heating at the ice-bed interface contributes significantly to total glacier mass balance and subglacial meltwater flux, yet modelling this basal melt process in Greenland has received minimal research attention. A one-dimensional dynamic ice-flow model is calibrated to the present day longitudinal profiles of 10 major Greenland outlet glaciers and ice streams (including the Jakobshavn Isbrae, Petermann Glacier and Helheim Glacier) and is validated against published ice flow and surface elevation measurements. Along each longitudinal profile, basal melt is calculated as a function of ice flow velocity and basal shear stress. The basal shear stress is dependent on the effective pressure (difference between ice overburden pressure and water pressure), basal roughness and a sliding parametrization. Model output indicates that where outlet glaciers and ice streams terminate into the ocean with either a small floating ice tongue or no floating tongue whatsoever, the proportion of basal melt to total melt (surface, basal and submarine melt) is 5-10% (e.g. Jakobshavn Isbrae; Daugaard-Jensen Glacier). This proportion is, however, negligible where larger ice tongues lose mass mostly by submarine melt (~1%; e.g. Nioghalvfjerdsfjorden Glacier). Modelled basal melt is highest immediately upvalley of the grounding line, with contributions typically up to 20-40% of the total melt for slippery beds and up to 30-70% for resistant beds. Additionally, modelled grounding line and calving front migration inland for all outlet glaciers and ice streams of hundreds of metres to several kilometres occurs. Including basal melt due to frictional heating in outlet glacier and ice stream models is important for more accurately modelling mass balance and subglacial meltwater flux, and therefore, more accurately modelling outlet glacier and ice stream dynamics and responses to future climate change.
Sevestre, H.; Benn, D.
Surge-type glaciers are scattered in a non-random fashion, gathered in clusters in some glaciated regions. One group of clusters forms an Arctic and Sub-Arctic 'crescent', spanning from Alaska-Yukon, through Arctic Canada, West and East Greenland, Iceland, Svalbard and Novaya Zemlya. Another cluster occurs in western High Asia, including the Karakoram Mountains. Although several studies have assessed the influence of environmental controls on surging, so far none has provided a satisfactory explanation for the geographical location of these clusters. The distribution of such glaciers undoubtedly holds the keys of a better understanding on the controls on surging behaviour. For this study, two glacier populations are considered. First, a global inventory of glacier surges has been compiled, based on published observations, field reports and remote sensing studies. This digital database is structured in three tables, respectively providing information on the location and geometry of each surge-type glacier, surge dates and magnitude, and methodology employed at the time of observation. This global dataset is compared to the population of "non-surge-type glaciers" based on the Randolph Glacier Inventory version 2.0 excluding the inventoried surging glaciers. In both populations, glaciers are classified depending on their geometry and thermal regime. Downscaled climatic datasets are used to identify climatic envelopes associated with clusters of surging glaciers. We identified which environments are most prone to be associated to glacier surging, and examined the influence of these parameters on the surge cycle duration and character. These results emphasize the importance of external controls on surging (as against individual surges), and promote the need to study this behaviour in the frame of an energy-balance budget.
Machguth, H.; Huss, M.
Glacier length is an important measure of glacier geometry. Nevertheless, global glacier inventories are mostly lacking length data. Only recently semi-automated approaches to measure glacier length have been developed and applied regionally. Here we present a first global assessment of glacier length using an automated method that relies on glacier surface slope, distance to the glacier margins and a set of trade-off functions. The method is developed for East Greenland, evaluated for East Greenland as well as for Alaska and eventually applied to all ~ 200 000 glaciers around the globe. The evaluation highlights accurately calculated glacier length where digital elevation model (DEM) quality is high (East Greenland) and limited accuracy on low-quality DEMs (parts of Alaska). Measured length of very small glaciers is subject to a certain level of ambiguity. The global calculation shows that only about 1.5% of all glaciers are longer than 10 km, with Bering Glacier (Alaska/Canada) being the longest glacier in the world at a length of 196 km. Based on the output of our algorithm we derive global and regional area-length scaling laws. Differences among regional scaling parameters appear to be related to characteristics of topography and glacier mass balance. The present study adds glacier length as a key parameter to global glacier inventories. Global and regional scaling laws might prove beneficial in conceptual glacier models.
C. I. Millar; R. D. Westfall
Rock glaciers and related periglacial rock-ice features (RIFs) are common landforms in high, dry mountain ranges, and widely distributed throughout canyons of the Sierra Nevada, California, USA (Millar & Westfall, in press). Due to insulating rock carapaces, active rock glaciers (ice-cored) have been documented to maintain ice longer, and thus contribute to more enduring hydrologic output, under past warming climates
This video shows how a NASA glaciologist has learned about glaciers and how their formation could be related to climate change. It features nine fly-bys over 3-dimensional glaciers, live video footage of ice fronts calving into the sea, and picture sequences of historical and satellite data.. Length:13:15.
A video from the Extreme Ice Survey in which Dr. Tad Pfeffer and photographer Jim Balog discuss the dynamics of the Columbia glacier's retreat in recent years through this time-lapse movie. Key point: glacier size is being reduced not just by glacial melting but due to a shift in glacial dynamics brought on by climate change.
Characteristics of ocean waters reaching Greenland's glaciers Fiammetta STRANEO,1 David A of Geography, University of British Columbia, Vancouver, Canada ABSTRACT. Interaction of Greenland's marine the glaciers range from 4.588C in the southeast, to 0.168C in northwest Greenland, consistent with the distance
Ian Joughin; Waleed Abdalati; Mark Fahnestock
It is important to understand recent changes in the velocity of Greenland glaciers because the mass balance of the Greenland Ice Sheet is partly determined by the flow rates of these outlets. Jakobshavn Isbræ is Greenland's largest outlet glacier, draining about 6.5 per cent of the ice-sheet area, and it has been surveyed repeatedly since 1991 (ref. 2). Here we
van Beusekom, A. E.; O'Neel, S.; March, R. S.; Sass, L. C.
Resolving the relationship between glacier surface-forcing (climate) and glacier geometry changes is accomplished through mass-balance estimates which can be made with remote sensing methods or field-based observations. The small scale of Alaskan glaciers has prevented remote sensing methods until recently, and field data are essential for validating new techniques. Field data provide the only long duration record that can be studied with respect to climate. The United States Geological Survey has maintained a 44-year mass-balance program at Alaska’s Gulkana Glacier and Wolverine Glacier. We have reanalyzed the Alaskan benchmark glaciers mass balance time series so that all data are treated similarly and systematically. Both glaciers are undergoing sustained mass loss with an increasing rate in recent years. However, the magnitude of the calculated loss depends on the number and location of the data collection sites. We explore the sensitivity of the glacier-wide balance estimates to the method of integration used on the necessarily point data. The robustness of the balance is strengthened with use of independent photogrammetric measurements.
ENVIRONMENTAL HAZARDS OF AVALANCHES: PRELIMINARY RESEARCH IN GLACIER NATIONAL PARK Site Focus: Balu Pass, Glacier National Park, B.C. Avalanche path near Balu Pass. (Photo Courtesy of: www in avalanche areas? #12;Researchers · Ben Ferrel · Keri Laughlin · Kevin McPhedran · Mark Brown · also thanks
Mass balance of Vatnaj¨okull outlet glaciers reconstructed back to 1958 L. A. Rasmussen Department seasonal components of mass balance of five Vatnaj¨okull outlet glaciers. Over the period of observations of mass balance between 1991 and 2001, it had percentage r2 rang- ing from 41 to 93 for winter balance bw
The second repeat photograph documents significant changes that have occurred during the 63 years between photographs A and C, and during the 54 years between photographs B and C. Muir Glacier has retreated out of the field of view and is now more than 7 kilometers northwest. Riggs Glacier has retre...
Instructions for Glacier Recession Lesson Objective: Students will learn: - about the connection post-discussion) The movie or some other type of lesson relating glaciers to climate change should amount of ice and multiply by 100. If using Option 3 (GIS lesson on computers): #12;
;#12;Preface The exciting thing about the present Master thesis is that it combines the fields of Car- tography. The glacier states are reconstructed by digitizing the glacier tongues from historical images. Since the camera parameters of these images are unknown, the image georeferencing is done first. Camera parameters
V. Kaufmann; R. Ladstädter
Rock glaciers are striking phenomena of high mountain permafrost. These periglacial landforms are composed of rock and ice and creep downslope at a typical rate of a few decimeters per year. This movement and other surface changes can be measured by various observation techniques. In this paper a digital-photogrammetric approach to rock glacier monitoring is described based on multi- temporal
Koppes, M.; Hallet, B.; Stewart, R.
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 erosion rates. Preliminary results indicate 1) that high rates of retreat of the ice front occur during years in which the total input of snow into the glacier is balanced by the total ablation, and hence the residual flux of ice at the terminus is insufficient to compensate for the calving, and 2) that the highest basin- wide erosion rates reflect years in which total ice accumulation is lower and retreat rates are high. Interestingly, basin-wide erosion rates from these glaciers are up to an order of magnitude higher than long- term exhumation rates derived from detrital apatite thermochronometry in the basins, indicating that current rates of erosion far exceed long-term rates, and are reflective of periods of warming climate and enhanced glacial retreat.
O'Neel, S.; Pfeffer, W. T.; Howat, I. M.; Conway, H.; Columbia Glacier Consortium
Since fulfilling Austin Post’s prediction of impending retreat in the late 1970s, Columbia Glacier has repeatedly surprised both casual and careful observers with its ability for rapid change. Over the last three decades, Columbia Glacier has lost approximately 18 km of its original 66 km length, while thinning by approximately 50% at the present terminus. The total ice volume lost to the Gulf of Alaska Estimates upwards of 120 km3 constrain the total ice volume lost to the Gulf of Alaska. Recently, the terminus supported a ~1.5 km long floating tongue for over than a year, contradicting the common assumption that the mechanical properties of temperate ice prohibit flotation over sustained time intervals. The rich history of study offers an opportunity to better understand tidewater glacier retreat, and a valuable analog to the dynamic instability underway at several ice sheet outlet glaciers. Current research aims to improve processing resolution of existing aerial photographic data, while complimenting the 30-year photogrammetric record with a suite of field observations. Recent instrumentation includes: oblique time lapse and still imagery, semi-permanent GPS, airborne radar, mass balance, passive seismology and LiDAR. This presentation will focus on innovative methods developed in recent field seasons, sharing insight each has provided into the retreat process . 1The Columbia Glacier Consortium consists of: Fabian Walter (SIO), Kenichi Matsuoka (NPI), Ben Smith (UW), Ethan Welty (CU-Boulder), Chris Larsen (UAF), Dave Finnegan (CRREL), Dan McNamara (USGS), Yushin Ahn (OSU), Julie Markus (OSU), Adam LeWinter (EIS).
Richard A. Shakesby; John A. Matthews; Stefan Winkler
Lichenometric evidence and Schmidt hammer R-values are used to date Holocene moraine sequences in front of six high-altitude (> 1500 m) glaciers in Breheimen, central southern Norway. At three glacier forelands with southerly aspects (Høgsetbreen, Vestre Høybre and Østre Høybre), relatively small (?4 m high) discrete boulder moraine ridges are shown to date from the ‘Little Ice Age’. The remaining
Licul, Aleksandar; Herman, Frédéric; Podladchikov, Yuri; Räss, Ludovic; Omlin, Samuel
Two different approaches are commonly used in glacier ice flow modeling: models based on asymptotic approximations of ice physics and full stokes models. Lower order models are computationally lighter but reach their limits in regions of complex flow, while full Stokes models are more exact but computationally expansive. To overcome this constrain, we investigate the potential of GPU acceleration in glacier modeling. The goal of this preliminary research is to develop a three-dimensional full Stokes numerical model and apply it to the glacier flow. We numerically solve the nonlinear Stokes momentum balance equations together with the incompressibility equation. Strong nonlinearities for the ice rheology are also taken into account. We have developed a fully three-dimensional numerical MATLAB application based on an iterative finite difference scheme. We have ported it to C-CUDA to run it on GPUs. Our model is benchmarked against other full Stokes solutions for all diagnostic ISMIP-HOM experiments (Pattyn et al.,2008). The preliminary results show good agreement with the other models. The major advantages of our programming approach are simplicity and order 10-100 times speed-up in comparison to serial CPU version of the code. Future work will include some real world applications and we will implement the free surface evolution capabilities. References:  F. Pattyn, L. Perichon, A. Aschwanden, B. Breuer, D.B. Smedt, O. Gagliardini, G.H. Gudmundsson, R.C.A. Hindmarsh, A. Hubbard, J.V. Johnson, T. Kleiner, Y. Konovalov, C. Martin, A.J. Payne, D. Pollard, S. Price, M. Ruckamp, F. Saito, S. Sugiyama, S., and T. Zwinger, Benchmark experiments for higher-order and full-Stokes ice sheet models (ISMIP-HOM), The Cryosphere, 2 (2008), 95-108.
Skidmore, Mark L.; Foght, Julia M.; Sharp, Martin J.
The debris-rich basal ice layers of a high Arctic glacier were shown to contain metabolically diverse microbes that could be cultured oligotrophically at low temperatures (0.3 to 4°C). These organisms included aerobic chemoheterotrophs and anaerobic nitrate reducers, sulfate reducers, and methanogens. Colonies purified from subglacial samples at 4°C appeared to be predominantly psychrophilic. Aerobic chemoheterotrophs were metabolically active in unfrozen basal sediments when they were cultured at 0.3°C in the dark (to simulate nearly in situ conditions), producing 14CO2 from radiolabeled sodium acetate with minimal organic amendment (?38 ?M C). In contrast, no activity was observed when samples were cultured at subfreezing temperatures (??1.8°C) for 66 days. Electron microscopy of thawed basal ice samples revealed various cell morphologies, including dividing cells. This suggests that the subglacial environment beneath a polythermal glacier provides a viable habitat for life and that microbes may be widespread where the basal ice is temperate and water is present at the base of the glacier and where organic carbon from glacially overridden soils is present. Our observations raise the possibility that in situ microbial production of CO2 and CH4 beneath ice masses (e.g., the Northern Hemisphere ice sheets) is an important factor in carbon cycling during glacial periods. Moreover, this terrestrial environment may provide a model for viable habitats for life on Mars, since similar conditions may exist or may have existed in the basal sediments beneath the Martian north polar ice cap. PMID:10919772
Glacier mass balance and secular changes in mountain glaciers and ice caps are evaluated from the annual net balance of 137\\u000a glaciers from 17 glacierized regions of the world. Further, the winter and summer balances for 35 glaciers in 11 glacierized\\u000a regions are analyzed. The global means are calculated by weighting glacier and regional surface areas. The area-weighted global\\u000a mean
Lewis A. Owen; Glenn Thackray; Robert S. Anderson; Jason Briner; Darrell Kaufman; Gerard Roe; William Pfeffer; Chaolu Yi
Mountain glaciers are sensitive probes of the local climate, and, thus, they present an opportunity and a challenge to interpret climates of the past and to predict future changes. Furthermore, glaciers can constitute hazards, including: glacier outburst floods; changes in the magnitude and timing of runoff in the mountains and adjacent regions; and, through worldwide loss of glacier ice, a
Climate downscaling for estimating glacier mass balances in northwestern North America: Validation] An atmosphere/glacier modeling system is described for estimating the mass balances of glaciers in both current to force a precipitation- temperature-area-altitude (PTAA) glacier mass balance model with daily maximum
Eduard Yu Osipov
The spatial extent of the Last Glacial Maximum (LGM) glaciers (MIS 2) in the northwest of the Barguzinsky Ridge has previously been mapped. Geographical information system (GIS)-computing of the glaciers' quantitative parameters allowed us to use various methods to evaluate the former equilibrium-line altitudes (ELAs) for the 10 largest glaciers. ELAs on reconstructed glaciers were calculated using four common methods:
Wittmeier, Hella E.; Bakke, Jostein; Vasskog, Kristian; Trachsel, Mathias
Late Glacial and Holocene glacier 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 glacier 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 glacier-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 glacier 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 glacier activity in the distal glacier-fed lakes. The complete deglaciation of the valley of Sør-Tverrfjorddalen occurred ?10,000 cal. a BP, followed by a reduced or absent glacier during the Holocene Thermal Optimum. The Langfjordjøkelen ice cap reformed with the onset of the Neoglacial ?4100 cal. a BP, and the gradually increasing glacier 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 glacier fluctuations. Periods of reduced glacier activity were centered around 1880, 1600, 1250 and 950 cal. a BP, while intervals of increased glacier activity occurred around 1680, 1090, 440 and 25 cal. a BP. The large-scale Holocene glacier activity of the Langfjordjøkelen ice cap is consistent with regional temperature proxy reconstructions and glacier variability across Norway. Long-term changes in the extent of the northern outlet of the Langfjordjøkelen ice cap largely followed trends in regional summer temperatures, whereas winter season atmospheric variability may have triggered decadal-scale glacial fluctuations and generally affected the amplitude of glacier events.
Sigurdsson, Oddur; Williams, Richard S., Jr.
Climatic changes and resulting glacier fluctuations alter landscapes. In the past, such changes were noted by local residents who often documented them in historic annals; eventually, glacier variations were recorded on maps and scientific reports. In Iceland, 10 glacier 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 glaciers was written. Therefore, Iceland distinguishes itself in having a more than 300-year history of observations by Icelanders on its glaciers. A long-term collaboration between Oddur Sigurdsson and Richard S. Williams, Jr., led to the authorship of three books on the glaciers of Iceland. Much effort has been devoted to documenting historical glacier research and related nomenclature and to physical descriptions of Icelandic glaciers 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 glacier 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 of the three books; it is being published in both English and Icelandic editions. This book provides information about all named glaciers in Iceland, historic and modern. Descriptions, with geographic coordinates, and bibliographic citations to all glacier place-names on published maps, books, and scientific articles are included. Maps, oblique aerial photographs, ground photographs, and satellite images document each of the 269 modern named glaciers of Iceland. The third book, Glaciers of Iceland, is Chapter D of the 11-chapter [volume] U.S. Geological Survey Professional Paper 1386-A-K. Chapter D includes a 1:500,000-scale Map of the Glaciers of Iceland; it is a comprehensive historical and modern review and assessment of what is currently known about glaciers in Iceland's eight Regional Glacier Groups from a review of the scientific literature and from analysis of maps and remotely sensed data (ground, airborne, and satellite); topics include geology and geography, climate and climate variability, types of glaciers, history of glacier variation (including the 21 surge-type glaciers), and frequency and magnitude of volcanic and lacustrine jokulhlaups.
Tangborn, Wendell V.; Mayo, Lawrence R.; Scully, David R.; Krimmel, Robert M.
Combined ice and water balances were measured in the 1967 hydrologic year (October 1-September 30) on four glaciers in western North America ranging in latitude from 37 deg to 63 deg N. This hydrologic year was characterized by heavier than normal winter precipitation in California and Washington and abnormally dry winter conditions in coastal Alaska. In summer the western conterminous states were abnormally dry and central and southern Alaska experienced very wet conditions. Maclure Glacier (lat 37 deg 45' N., 3,650-m (metres) mean equilibrium line altitude) had an above normal winter balance of 3.46 m and a positive annual balance of 1.05 m (metres of water equivalent). South Cascade Glacier (lat 48 deg 22' N., 1900-m mean equilibrium line altitude) had a winter balance of 3.28 m, slightly above average. Above normal summer ablation resulted in a final annual balance of -0.58 m, slightly more negative than has been the case for the past decade. Wolverine Glacier's (lat 60 deg 24' N., 1,200-m mean equilibrium line altitude) winter balance was 1.17 m, considerably below normal; the annual balance was -2.04 m. Gulkana Glacier (lat 63 deg 15' N., 1,700-m mean equilibrium line altitude) had a winter balance of 1.05 m, approximately normal for this glacier; the final annual balance was -0.30 m.
Colaprete, A.; Haberle, R. M.; Montmessin, F.; Scheaffer, J.
Numerous geologic features suggest the presence of ice flow on the surface of mars. These features include lobate debris aprons, concentric crater fill, and lineated valley fill. The lateral extent of these features can range from 100 meters to over 20 km. Previous work has demonstrated that these features could not have formed in current Martian conditions. It has long been speculated that changes in Mars orbital properties, namely its obliquity, eccentricity, and argument of perihelion, can result in dramatic changes to climate. Recent climate model studies have shown that at periods of increased obliquity north polar water ice is mobilized southward and deposited at low ad mid latitudes. Mid latitude accumulation of ice would provide the necessary conditions for rock glaciers to form. A time-marching, finite element glacier model is used to demonstrate the ability of ice and ice-rock mixtures to flow under Martian paleoclimate conditions. Input to this model is constrained by the NASA Ames Mars General Circulation Model (MGCM).
Yasunari, Teppei J.
The subject of climate change in the Tibetan Plateau (TP) and Himalayas has taken on increasing importance because of the availability of water resources from their mountain glaciers (Immerzeel et al 2010). Many of the glaciers over these regions have been retreating, while some are advancing and stable (Yao et al 2004, Scherler et al 2011). Other studies report that some glaciers in the Himalayas show acceleration of their shrinkage (e.g., Fujita and Nuimura 2011). However, the causes of glacier melting are still difficult to grasp because of the complexity of climatic change and its influence on glacier issues. Despite this, it is vital that we pursue further study to enable future predictions of glacier changes. The paper entitled 'Climate and glacier change in southwestern China during the past several decades' by Li et al (2011) provided carefully analyzed, quality controlled, long-term data on atmospheric temperature and precipitation during the period 1961-2008. The data were obtained from 111 Chinese stations. The researchers performed systematic analyses of temperature and precipitation over the whole southwestern Chinese domain. They discussed those changes in terms of other meteorological components such as atmospheric circulation patterns, radiation and altitude difference, and then showed how these factors could contribute to climate and glacier changes in the region. Air temperature and precipitation are strongly associated with glacier mass balance because of heat balance and the addition of mass when it snows. Temperature warming trends over many places in southwestern China were unequivocally dominant in all seasons and at higher altitudes. This indicates that the heat contribution to the glaciers has been increasing. On the other hand, precipitation has a wider variability in time and space. It is more difficult to clearly understand the effect of precipitation on the climate and glacier melting characteristics in the whole of southwestern China as a collective view. However, the precipitation patterns in southwestern China are probably modulated by climate feedbacks through many factors. Precipitation seasonality may also affect the climatic sensitivity of glacier mass balance (Fujita 2008). In addition to the authors' main focus above, other factors, also probably directly and indirectly, influence the climate and glacier mass balance changes. Those factors are: (a) The debris-covered effect which heats (if it is thin) or insulates (if it is thick) the ice below the debris; it probably causes no uniform response on glacier melting (Scherler et al 2011); (b) Interaction between glacial lakes and exposed ice parts on glaciers (e.g., Sakai et al 2009, Fujita et al 2009); (c) The atmospheric heating effect over the foothills of the Himalayas due to the Atmospheric Brown Cloud (ABC), including absorbing aerosols such as black carbon, dust and organic matters (Ramanathan et al 2007), the so called Elevated Heat Pump (EHP) effect suggested by Lau et al (2006, 2010); (d) The snow darkening effect over non debris-covered parts of glaciers as the absorbing aerosol depositions reduce snow albedo and accelerate snow melting by absorbing more solar energy at the snow surface (Warren and Wiscombe 1980, Flanner et al 2007, 2009, Yasunari et al 2010, Qian et al 2011); (e) Another kind of snow darkening effect over non debris-covered glaciers due to the growth of biological activities, with dark-colored materials on glaciers also reducing snow albedo (Takeuchi et al 2001); (f) Other factors on snow albedo reductions such as snow grain size, specific surface area and depth changes, melt-water effect on snow, and changes in solar illumination conditions (e.g., Wiscombe and Warren 1980, Flanner et al 2006, Yasunari et al 2011, Aoki et al 1999, 2011); and finally, (g) Feedbacks via interactions between the snow surface and atmosphere including all the factors above. What I'd like to emphasize is that the atmospheric warming trend indicated by Li et al (2011) is robust and very likely associated with the dominant character
Zhang, Qianggong; Huang, Jie; Wang, Feiyue; Mark, Loewen; Xu, Jianzhong; Armstrong, Debbie; Li, Chaoliu; Zhang, Yulan; Kang, Shichang
Western China is home to the largest aggregate of glaciers outside the polar regions, yet little is known about how the glaciers in this area affect the transport and cycling of mercury (Hg) regionally and globally. From 2005 to 2010, extensive glacier snow sampling campaigns were carried out in 14 snowpits from 9 glaciers over western China, and the vertical distribution profiles of Hg were obtained. The Total Hg (THg) concentrations in the glacier snow ranged from <1 to 43.6 ng L(-1), and exhibited clear seasonal variations with lower values in summer than in winter. Spatially, higher THg concentrations were typically observed in glacier snows from the northern region where atmospheric particulate loading is comparably high. Glacier snowpit Hg was largely dependent on particulate matters and was associated with particulate Hg, which is less prone to postdepositional changes, thus providing a valuable record of atmospheric Hg deposition. Estimated atmospheric Hg depositional fluxes ranged from 0.74 to 7.89 ?g m(-2) yr(-1), agreeing very well with the global natural values, but are one to two orders of magnitude lower than that of the neighboring East Asia. Elevated Hg concentrations were observed in refrozen ice layers in several snowpits subjected to intense melt, indicating that Hg can be potentially released to meltwater. PMID:22519575
Nagler, T.; Heidinger, M.; Rott, H.; Bippus, G.; Hetzenecker, M.; Scharrer, K.
Snow cover and glaciers, storing large amounts of fresh water, respond sensitively to climate change. Accurate inventories and monitoring of these resources is therefore important for climate impact assessment, water resources management, and hydrology. The Project "ASaG - Preparation for a GMES Downstream service for snow and glacier Monitoring in Alpine Regions", supported by the Austrian Research Promotion Agency (FFG), aims at the implementation of a satellite-based services for spatially detailed monitoring of snow cover and glaciers over extended area. Algorithms and processing lines for retrieval of snow extent from medium resolution optical and SAR satellite imagery are further improved in the project in order to optimally match the needs of users. The snow cover products are generated using data of the MODIS sensor operating on the Terra platform of NASA. The products are made available in near real time and are used in pre-operational tests for initialization and validation of hydrological models and distributed snow process models. Statistical snow information like snow area - elevation curves are generated for user specified basins using this information for runoff simulation and forecasting and for water management tasks. For mountain glaciers a processing line has been implemented for satellite-based products on glacier area, outlines, glacier zones (snow, ice) and ice velocity maps to be used for updating glacier inventories. The glacier products are generated for major Austrian glacier regions using new high resolution optical satellite data (SPOT-5) and SAR (TerraSAR-X, Cosmo-Skymed). The products comply with the European rules for geospatial information according to the INSPIRE directive in order to ensure interoperability of the data sets and are made accessible to users via internet. Project results are also exploited in wider within the EC-FP7 project "CryoLand - GMES Service Snow and Land Ice", a GMES Downstream Service developed under the lead of ENVEO (started in February 2011).
Brock, Benjamin; Rivera, Andres; Burger, Flavia; Bravo, Claudio
Glaciers of the semi-arid central Chilean Andes are an important freshwater source for the populous Central Valley region of Chile, but have been shrinking in recent decades. The surface energy balance of these glaciers is of high scientific interest as summer ablation occurs through both sublimation and melt. During the 2012-13 Austral Summer a glacio-meteorological monitoring programme was established on Olivares Alfa (3.9 km2, 4130-4800 m elevation) and Beta (8.3 km2, 3620-4850 m elevation) Glaciers and their forelands in the Upper Olivares Valley, 33°00'-33°11' S, 70°05'-70°15' W, approximately 50 km north-east of Santiago. This included complete automatic weather stations (AWSs) with sonic rangers to record surface ablation on the ablation zones of the two glaciers, and one AWS in the proglacial area of Olivares Alfa Glacier including precipitation gauge. To complement these point data, daily images of the glaciers were captured with fixed cameras in order to calculate snow cover and albedo distributions. To calculate the surface energy balance and rates of melt and sublimation, a model was developed which uses direct AWS measurements of the radiative fluxes and calculates the turbulent fluxes of sensible and latent heat using the bulk aerodynamic approach. The model also calculates the subsurface heat flux and includes a simple scheme to estimate refreezing of melt water within surface snow or ice. Meteorological data and model results for the December to May period will be presented in this paper. Model calculations match closely the cumulative ablation curve of the sonic ranger at Olivares Alfa, with a slight overestimation, and overestimate cumulative ablation recorded by the sonic ranger at Olivares Beta, possibly due, at least in part, to uncertain snow density values. Modelled cumulative ablation in the December-April period is 2.2 m water equivalent (w.e.) at Olivares Alfa (0.10 m sublimation, 2.10 m melt) and 2.34 m w.e. at Olivares Beta (0.18 m sublimation, 2.16 m melt). The surface energy balance is dominated by shortwave radiation, which is the only net energy input, apart from a minor contribution from sensible heat, while the main outputs of energy are net longwave radiation, melt and sublimation. Ablation is dominated by melt during the warmer midsummer months at the two AWS sites, with mean rates exceeding 30 mm w.e. per day. However, due to the high latent heat of sublimation, it is only in January and February that the melt energy flux clearly exceeds the sublimation energy flux. Sublimation rates are typically ~1 mm w.e. per day and are 50 to 100 % higher at Olivares Beta as a result of higher wind speed and surface temperature, despite similar air temperatures at the two sites. Melt rates are around twice as high in summer months with mean air temperature > -2° C, compared with cooler months. This implies that future atmospheric warming will accelerate shrinkage of these glaciers as the ablation regime switches increasingly from sublimation to a more efficient melt regime.
This National Park Service (NPS) site provides links to geology fieldnotes about National Parks, National Monuments, and National Recreation Areas having to do with glaciers. Where appropriate links are provided to geology, visitor information, photographs, maps, multimedia resources, related links, and teacher features (resources for teaching geology with National Park examples). This site divides the parks into the following glacier categories: Active alpine glaciation, continental glaciation landforms, alpine glaciation landforms, and Ice age flood landforms (scablands). Some of the parks mentioned include Glacier Bay National Park in Alaska, Acadia National Park in Maine, Lake Roosevelt National Recreation Area in Washington, and many more.
Paul, Frank; Le Bris, Raymond
Deriving glacier-specific elevation changes from DEM differencing and digital glacier outlines is rather straight-forward if the required datasets are available. Calculating such changes over large regions and including glaciers selected for mass balance measurements in the field, provides a possibility to determine the representativeness of the changes observed at these glaciers for the entire region. The related comparison of DEM-derived values for these glaciers 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 glaciers Gulkana and Wolverine for the overall changes of nearly 3200 glaciers 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 glacier outlines were taken from the USGS digital line graph (DLG) dataset, corrected with the digital raster graph (DRG) maps from USGS. Mean glacier specific elevation changes were derived based on drainage divides from a recently created inventory. Land-terminating, lake-calving and tidewater glaciers 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 glaciers (about -0.65 m / year) are very similar to the mean of the lake-calving and tidewater glaciers (about -0.6 m / year), but much more negative than for the land-terminating glaciers (about -0.24 m / year). The two mass balance glaciers are thus well representative for the entire region, but not for their own class. The different ways of considering positive elevation changes (e.g. setting them to zero or no data) influence the total values, but has otherwise little impact on the results (e.g. the correction factors are similar). The massive elevation loss of Columbia Glacier (-2.8 m / year) is exceptional and strongly influences the statistics when area-weighting is used to determine the regional mean. For the entire region this method yields more negative values for land-terminating and tidewater glaciers than the arithmetically averaged values, but for the lake-calving glaciers both are about the same.
Andreassen, Liss M.; Huss, Matthias; Melvold, Kjetil; Elvehøy, Hallgeir; Winsvold, Solveig H.
Whereas glacier areas in many mountain regions around the world now are well surveyed using optical satellite sensors and available in digital inventories, measurements of ice thickness are sparse in comparison and a global dataset does not exist. Since the 1980s ice thickness measurements have been carried out by ground penetrating radar on many glaciers in Norway, often as part of contract work for hydropower companies with the aim to calculate hydrological divides of ice caps. Measurements have been conducted on numerous glaciers, covering the largest ice caps as well as a few smaller mountain glaciers. However, so far no ice volume estimate for Norway has been derived from these measurements. Here, we give an overview of ice thickness measurements in Norway, and use a distributed model to interpolate and extrapolate the data to provide an ice volume estimate of all glaciers in Norway. We also compare the results to various volume-area/thickness-scaling approaches using values from the literature as well as scaling constants we obtained from ice thickness measurements in Norway. Glacier outlines from a Landsat-derived inventory from 1999-2006 together with a national digital elevation model were used as input data for the ice volume calculations. The inventory covers all glaciers in mainland Norway and consists of 2534 glaciers (3143 glacier units) covering an area of 2692 km2 ± 81 km2. To calculate the ice thickness distribution of glaciers in Norway we used a distributed model which estimates surface mass balance distribution, calculates the volumetric balance flux and converts it into thickness using the flow law for ice. We calibrated this model with ice thickness data for Norway, mainly by adjusting the mass balance gradient. Model results generally agree well with the measured values, however, larger deviations were found for some glaciers. The total ice volume of Norway was estimated to be 275 km3 ± 30 km3. From the ice thickness data set we selected glacier units or entire ice caps with sufficient data to interpolate mean ice thickness. Scaling constants c and ? were fitted by least square regression for totally 86 glacier units and 8 ice caps. The ice volume results from scaling were sensitive to how the glaciers are divided and scaling applied to glaciers divided into glacier units gave best results. Scaling laws for ice caps did not work well, as the mean thickness of the ice caps varies less than their areas and the sample of ice caps with sufficient measurement coverage was small. Calculated ice volumes range from 280 to 305 km3, much higher than values obtained from the literature (134-184 km3). As measurements are biased towards outlets from the largest and thickest ice caps, more measurements are needed for a better estimate of the present ice volume of the smaller glaciers.
Slayback, D. A.; Tucker, C. J.
We report on the systematic retreat of all glaciers in the tropics of the New World from the mid-1980s to the mid-2000s. These glaciers comprise 99% of the world’s tropical glaciers and occur in Bolivia, Peru, Ecuador, Colombia, Venezuela, and Mexico. It was necessary to use a large quantity of Landsat satellite data (124 images), selecting multiple images for every glacier for both epochs, to minimize confusion of glacier area with snow. Change in glacier extent was combined with a digital elevation model (DEM) to provide information on the elevation and aspect of areas of glacier recession. Overall, we found glacier recession of approximately 30% over twenty years, declining from ~2500 km2 from the mid-1980s to ~1800 km2 in the mid-2000s. In addition, there was a strong association of glacier recession with elevation and aspect. We discuss these trends in relation to hypothesized climatic influences.
Report - 2004 CONTENS 1. Summary 5 2. Introduction 5 3. Survey Projects 12 3.1 Lemon Creek Glacier in elevation and flow velocities as well as determining pressure and deformation. In addition to the Lemon
Intersection of Wawona Road and Glacier Point Road at Chinquapin. Restroom buildings in trees at left. Looking southeast - Wawona Road, Between South Entrance & Yosemite Valley, Yosemite Village, Mariposa County, CA
with deposits formed in contemporary glaciated environments. These new data are subsequently appraised in terms the warming climate and increasing precipitation. These new palaeoglaciological and palaeoenvironmental Weichselian; Younger Dryas; British Ice Sheet; Stratigraphy; Glacier dynamics; Palaeoglaciology; Scotland
USGS Research Ecologist Clint Muhlfeld holds a native westslope cutthroat trout in Glacier National Park. GNP is recognized as a range-wide stronghold for genetically pure westslope cutthroat trout. However, rainbow trout invasion and hybridization threatens these populations. ...
Lenaerts, J.; van Angelen, J.; van den Broeke, M. R.; Gardner, A. S.; Wouters, B.; van Meijgaard, E.
The Canadian Arctic Archipelago (CAA) contains the largest volume of glacier ice outside Greenland and Antarctica, equivalent to 0.22±0.03 m eustatic sea level. In the absence of significant solid ice discharge (D~5 Gt yr-1), CAA mass balance is largely dominated by surface mass balance (SMB), the difference between snow accumulation and meltwater runoff. Results from the Gravity Recovery and Climate Experiment (GRACE) satellites show that, following a recent atmospheric warming (1-2 K), CAA mass loss increased from 31±8 Gt yr-1 in 2004-2006 to 92±12 Gt yr-1 in the period 2007-2009. As yet, it has been unclear if this sharp increase in mass loss can be attributed to natural variability on decadal time scales, or that it marks the onset of a long-term warming and consequent CAA mass loss. In this study we use a high-resolution regional atmospheric climate model (RACMO2), coupled with a sophisticated snow/firn/ice column physics model, driven by ERA-reanalyses (1960-2011) to assess past and present-day CAA mass balance. Since we neglect D in the mass balance, mass anomalies can be attributed to SMB only, which enables direct comparison between RACMO2 and GRACE (RL04). In the period 2004-2011, CAA lost ice at a rate of 64±10 Gt yr-1 according to RACMO2, which agrees with GRACE (72±6 Gt yr-1). The longer temporal coverage of the RACMO2 results enables us to put the recent mass loss in a longer-term perspective. RACMO2 suggests that NCAA was in approximate mass balance before the year 2000, whereas the Southern CAA (SCAA) also lost mass in 1960-2000 at a rate of 15±11 Gt yr-1, a finding that agrees with recent estimates from altimetry and stereographic imaginery (-11±4 Gt yr-1 in 1963-2006). To assess CAA mass loss for the remainder of the 21st century, RACMO2 was forced at the lateral boundaries by HadGEM2-ES, a fully coupled CMIP5 general circulation model (GCM). This GCM in turn was forced with the modest warming scenario RCP45, resulting in a 21st century warming that is similar to the average of all AR5 scenarios. Mean CAA glacier SMB decreases to -144±33 Gt yr-1, and mass loss is then larger in NCAA (82±31 Gt yr-1) than in SCAA (62±10 Gt yr-1). Mass loss is dominated by meltwater runoff, only partially (~30%) compensated by increasing precipitation. We apply the significant correlation between CAA SMB and CAA T2m to all AR5 multi-model realizations (~6500 single years) and found out this estimate is relatively conservative. More importantly, CAA glacier growth (SMB>0) is predicted in only 0.15% of the ensemble members, rendering it highly unlikely that current CAA glacier mass loss will be reversed. Based on the full AR5 ensemble, we estimate the total CAA mass loss at 12400±8500 Gt yr-1 until 2100, equivalent to 0.35±0.24 mm yr-1. This makes CAA the largest cryospheric contributor to 21st century sea level rise outside Greenland and Antarctica.
Treichler, D.; Kaeaeb, A.
While the use of ICESat GLAS data is well established for monitoring elevation changes on ice sheets, this data holds valuable information also for more complex terrain and small glaciers, as recently demonstrated for example for high mountain Asia. This study aims at exploring the potential and limitations of ICESat over glaciated, mountainous terrain on the example of Southern Norway. The glaciers in Southern Norway are spread over an area of roughly 100'000 km2 in size. Despite high cloud coverage due to coastal proximity, we found that on average 85% of the laser returns per operational campaign contain valid elevation information from the Earth's surface, as compared with reference elevations from DEMs of 20m spatial resolution.While only 1.5% of the study area is glacierised, the laser footprints on ice represent Southern Norway's glaciers well in elevation, aspect, slope, glacier size, and spatial distribution, even for individual campaigns. With decreasing number of data points towards the end of ICESat's operational period, relative oversampling of larger ice bodies and spatial clumping occurs. Employing GLAS data for smaller or less glacierised areas might thus lead to a spatial bias due to overrepresentation of a particular glacier, and contrasting mass change estimates compared to traditional mass balance programs that are rather biased towards smaller valley glaciers with different glacier behaviour. Using only data captured at the end of the hydrological year as a proxy for yearly net mass balance, we find a slightly negative glacier surface elevation trend of -0.28 +/- 0.1 m ice per year for the ICESat period 2003 to 2008. This is in accordance with the heterogeneous but overall negative net balance in the range of -0.82 to +0.36 m w.eq. per year obtained by traditional in-situ measurements for ten glaciers in Southern Norway. When including the ICESat winter campaigns, yearly variations in snow height of 50 to 100 cm in the lowlands are accurately represented in particular on ice-free ground. The effect of elevation is reflected in increasing snow depths peaking later in the season for areas above ca. 1500m. Caution should thus be taken when including snow-on data for glacier surface elevation change estimates, as the combined variations are likely to bias the actual glacier signal.
Thompson, L. G.; Brecher, H. H.; Mosley-Thompson, E.; Hardy, D. R.; Mark, B. G.
The dramatic loss of Kilimanjaro's ice cover has attracted global attention. The three remaining ice fields on the plateau and the slopes are both shrinking laterally and rapidly thinning. Summit ice cover (areal extent) decreased ?1% per year from 1912 to 1953 and ?2.5% per year from 1989 to 2007. Of the ice cover present in 1912, 85% has disappeared and 26% of that present in 2000 is now gone. From 2000 to 2007 thinning (surface lowering) at the summits of the Northern and Southern Ice Fields was ?1.9 and ?5.1 m, respectively, which based on ice thicknesses at the summit drill sites in 2000 represents a thinning of ?3.6% and ?24%, respectively. Furtwängler Glacier thinned ?50% at the drill site between 2000 and 2009. Ice volume changes (2000–2007) calculated for two ice fields reveal that nearly equivalent ice volumes are now being lost to thinning and lateral shrinking. The relative importance of different climatological drivers remains an area of active inquiry, yet several points bear consideration. Kilimanjaro's ice loss is contemporaneous with widespread glacier retreat in mid to low latitudes. The Northern Ice Field has persisted at least 11,700 years and survived a widespread drought ?4,200 years ago that lasted ?300 years. We present additional evidence that the combination of processes driving the current shrinking and thinning of Kilimanjaro's ice fields is unique within an 11,700-year perspective. If current climatological conditions are sustained, the ice fields atop Kilimanjaro and on its flanks will likely disappear within several decades. PMID:19884500
Davis, P. Thompson
In many areas of the American Rocky Mountains (Colorado, Wyoming, Utah, Idaho, Montana), Cascade Range (Washington, Oregon), and the Sierra Nevada (California), radiocarbon ages suggest that ice receded to near present limits before 10 ka BP. A pre-Altithermal readvance or stillstand left moraines ca. 1-3 km beyond and ca. 50-300 m below present glacier margins. At one locality on Glacier Peak in Washington, these deposits are perhaps dated to the early Holocene, but in general these deposits are probably at least 10 ka old. Glacial advances during the Altithermal (ca. 8 to 5 ka BP) elsewhere are rare; radiocarbon evidence for Altithermal glacial advances in the Colorado Front Range is questionable. The earliest radiocarbon-dated Neoglacial advances occurred about 5 ka BP in the Washington Cascades; moraines and related deposits believed to be of early Neoglacial age (i.e. 5 to 3 ka BP) elsewhere are poorly dated. For example, moraines believed to date to the early Neoglacial in Colorado (Triple Lakes) and Wyoming (Temple Lake) are actually late Pleistocene age, based on radiocarbon ages derived from lake sediments at the type localities. Although relative-age data (i.e. lichens, rock weathering, soils) from many areas suggest a three-fold Neoglacial sequence, little supporting radiocarbon evidence is available. However, tephrochronology distinguishes three Neoglacial advances near Mount Rainier in Washington. In most mountain ranges of the western United States, fresh, unweathered, sharp-crested moraines usually adjacent to present ice margins, or near headwalls in empty cirques, date to the Little Ice Age of the last several centuries. However, detailed photographic or other historical records of glacial fluctuations during the last century are rare, and detailed mass balance studies rarer still. Whether or not pre-Little Ice Age glacial fluctuations in the American Cordillera are synchronous must await better radiometric dating of local moraine sequences.
Kaeaeb, A.; Zurich GLIMS Team; Flagstaff GLIMS Team
Since the year 2000 imagery from ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer, on board TERRA) is available for observing global land ice. Its spectral and geometric properties include 3 bands in VNIR with 15m resolution, 6 bands in SWIR with 30m, 5 bands in TIR with 90m, and a 15m-resolution NIR along-track stereo-band allowing for terrain height measurements. Of special interest for glaciological studies are the high spatial resolution in SWIR, the stereo-, and the pointing-capabilities of ASTER. Here, we evaluate the benefit from ASTER data for glacier studies by accuracy assessments and application studies for test sites in the European Alps, New Zealand Alps and Himalayas: \\- Algorithms for map transformation, DEM extraction, glacier classification and ice velocity measurement are presented. \\- ASTER-DEMs for high mountain environment are compared to ones derived from high-resolution aerial photogrammetry. \\- Multi-spectral glacier classification from ASTER data is compared to glacier mapping from other high-resolution air- and space-borne sensors, such as aerial imagery and Landsat data. \\- The potential of repeated ASTER imagery for ice velocity measurements is demonstrated and evaluated using field measurements. \\- Combination of above techniques represents a powerful tool for assessing glacier-related hazards, as exemplified for glacier-lake outbursts and ice avalanches. The studies show that ASTER is in deed able to give new impulses for worldwide glacier monitoring. Its main limitation for that purpose might consist in the small swath width of 60km. The above technical highlights together with the latter limitation make ASTER and other optical sensors, especially Landsat7 ETM+, complementing each other for glacier monitoring purposes.
Wilkens, N. M.; Kleiner, T.; Humbert, A.
Pine Island Glacier is a fast moving outlet glacier in the West Antarctic Ice Sheet. Several tributaries feeding the central ice stream characterise the flow field structure of this glacier. In the past decades the glacier has shown acceleration, thinning and a significant grounding line retreat. These ongoing processes are coinciding with a concentrated mass loss in the area around Pine Island Glacier, the Amundsen Sea Embayment. The area is of additional interest due to its retrograde bed slope. The postulated instability of the setting turns the glacier into an even more suitable object for modelling studies. One major challenge encountered when modelling the flow field of Pine Island Glacier is to reproduce the locally varying flow pattern, with its many tributaries. Commonly this difficulty is overcome by inversion for parameters controlling basal sliding. Our study is aimed at connecting basal sliding again to physical parameters. To achieve this we conduct experiments of Pine Island Glacier with the diagnostic 3D full-Stokes model COMice. The model is thermo-mechanically coupled and implemented with the commercial finite-element package COMSOL Multiphysics©. We use remotely sensed surface velocity data to validate our results. In a first step, the model is used to identify dominant local mechanisms that drive the flow of the different tributaries. We identify connections between the basal topography, the basal temperature, the driving stress and the basal roughness distribution. The thus gained information is used to confine basal sliding. Areas with similar qualitative characteristics are identified, and constant-sliding assumptions made for those. Additionally, the basal roughness distribution is matched onto a basal sliding parameter. This way the sliding law is again brought closer to its original meaning. Our results are important for prognostic model experiments, as we connect basal sliding to locally varying basal properties, which might lead to different responses of the tributaries to altered external forcing.
Glaciers, Climate, and Society is designed to be a central location where students, teachers, parents, and researchers can begin their search for information and resources regarding glacier hazards, climate, water, and the human dimensions of these issues. Featuring many photos and embedded videos, the site provides K-12 education resources, issue summaries, information on Professor Mark Carey's research in the Andes, a resources and links page, and much more.
PRATAP SINGH; K. S. RAMASASTRI; U. K. SINGH; J. T. GERGAN; D. P. DOBHAL
Observations of discharge, temperature and suspended sediment made at a gauging site established near the snout of the Dokriani glacier in the western Himalayan region are presented. These observations were made during a scientific expedition to this glacier over 21 days (23.8.1992-12.9.1992). Because of harsh weather conditions, obser vations could not be made for a longer period. The minimum streamflow
moving stations on rock glacier Low-cost L1 GPS receivers (blox) Power source: solar panels Local data Rock glacier GPS antennaGPS antenna Solar panelSolar panel Box incl.Box incl. -GPS receiverData logger Instruments Solar panelSolar panel (24W, 12V, 50x50cm)(24W, 12V, 50x50cm) Costs per station: 2
Tom-Pierre Frappé; Garry K. C. Clarke
Trapridge Glacier, a polythermal surge-type glacier located in the St. Elias Mountains, Yukon Territory, Canada, passed through a complete surge cycle between 1951 and 2005. Air photos (1951–1981) and ground-based optical surveys (1969–2005) are used to quantify the modifications in flow and geometry that occurred over this period. Yearly averaged flow records suggest that the active phase began ?1980, and
Tom-Pierre Frappé; Garry K. C. Clarke
Trapridge Glacier, a polythermal surge-type glacier located in the St. Elias Mountains, Yukon Territory, Canada, passed through a complete surge cycle between 1951 and 2005. Air photos (1951-1981) and ground-based optical surveys (1969-2005) are used to quantify the modifications in flow and geometry that occurred over this period. Yearly averaged flow records suggest that the active phase began ~1980, and
Larsen, C. F.; Bartholomaus, T. C.; O'Neel, S.; West, M. E.; Walter, F.; Kluskiewicz, D.
Our group initiated a multidisciplinary project in Icy Bay, Alaska during spring 2009. Building on our study of ice motion and seismicity of the Bering Glacier in 2007/8, this present work is focused on the relationships between ice velocity variations, iceberg calving and glacier-generated seismic events. We present preliminary analyses from the 2009 field season. Yahtse Glacier has suffered over 40 km of retreat since 1900, but has recently begun advancing at the calving margin. Laser altimetry measurements show the advance is not indicative of a positive balance. Extensive thinning occurs over much of the glacier at area averaged rates of 1-2 m/yr. Field instrumentation consists of fifteen broadband seismometers (five are deployed in the ice), ten continuously recording GPS stations, and four time-lapse cameras deployed near the calving front of Yahtse Glacier. A weather station, HD video and infrasound records compliment these primary instruments. Our observations indicate Yahtse Glacier is extremely active. Iceberg calving events occur roughly every 15 minutes during peak times, and frequently excite large seiches within the fiord that can last for tens of minutes. Significant motion of the glacier can be observed in the time lapse imagery from our newly installed cameras. Two temporary GPS stations deployed on the lower glacier in June 2009 indicate ice velocities of 16.5 m/day. A detailed human-observer record compiled during field visits is providing a record against which the seismic and infrasound data can be benchmarked. In addition to recording calving events, the seismic records of calving-excited seiches demonstrate the coupling of the fjord to the solid earth.
Paasche, O.; Bakke, J.; Schaefer, J. M.
Along the Antarctic Peninsula and across the sub-Antarctic islands most glaciers, regardless of size and configuration, are in a state of demise and have been so for several decades. An emerging question is: how unique is this modern retreat when compared to glacier activity in this region during the last 10 000 years, if at all and to what extent? And also, how is this pattern different from the Northern Hemisphere where glaciers generally were small or even absent during the Holocene Optimum (9000-6000 years ago) and expanding after the onset of the Neoglacial (4000 years ago), with a typical late maximum around the Little Ice age (1400-1800 AD)? Here we address these questions in an effort to further our understanding of natural environmental variability in the Southern Hemisphere on time scales, and with a resolution, high enough to capture glacier trends on multi-decadal to centennial time scales. This is accomplished by acquiring and analyzing new terrestrial glacier records from the remote island South Georgia (54-55°S, 36-38°W) covering at least the last 13 000 years. Results from downstream lake sediment archives together with cosmogenic nuclide dating of a complete moraine sequence add new insight to the glacier history of South Georgia. The Hodges cirque glacier, which was mapped and investigated intermittently by the British Antarctic Survey between 1955-1982, was according to our observations present during the entire Holocene, but smaller advances were superimposed on a long-term pattern of retreat. The Hodges, as one of the first glaciers on South Georgia, had completely melted away by 2008, which indicate a retreat of circa 900 meter since early Holocene.
García-Descalzo, Laura; García-López, Eva; Postigo, Marina; Baquero, Fernando; Alcazar, Alberto; Cid, Cristina
Little is known about the viability of eukaryotic microorganisms preserved in icy regions. Here we report on the diversity of microbial eukaryotes in ice samples derived from four Pyrenean glaciers. The species composition of eukaryotic communities in these glaciers is unknown mostly because of the presence of a multi-year ice cap, and it is not clear whether they harbor the same populations. The recent deglaciation of these areas is allowing an easy access to glacial layers that correspond to the “Little Ice Age” although some isolated deposits are attributed to previous glacial cycles. In this study, we use molecular 18S rRNA-based approaches to characterize some of the microbial eukaryotic populations associated with Pyrenean glaciers. Firstly, we performed a chemical and microscopical characterization of ice samples. Secondly, molecular analyses revealed interesting protist genetic diversity in glaciers. In order to understand the microbial composition of the ice samples the eukaryotic communities resident in the glacial samples were examined by amplifying community DNA and constructing clone libraries with 18S rRNA primers. After removal of potential chimeric sequences and dereplication of identical sequences, phylogenetic analysis demonstrated that several different protists could be identified. Protist diversity was more phylum rich in Aneto and Monte Perdido glaciers. The dominant taxonomic groups across all samples (>1% of all sequences) were Viridiplantae and Rhizaria. Significant variations in relative abundances of protist phyla between higher and lower glaciers were observed. At the genus level, significant differences were also recorded for the dominant genera Chloromonas, Raphidonema, Heteromita, Koliella, and Bodomorpha. In addition, protist community structure showed significant differences between glaciers. The relative abundances of protist groups at different taxonomic levels correlated with the altitude and area of glaciers and with pH of ice, but little or no relationships to other chemical characteristics were found. PMID:23515855
Ganjoo, R. K.
The Ladakh Mountains house approximately 4500 glaciers in its two major basins, namely Indus (1800 glaciers) and Shyok (2700 glaciers).Glaciers in Indian Himalaya have been under monitor for past about five decades. Monitoring of scores of glaciers have been both in terms of documentary record and field studies of the glaciers in northwest Himalaya. The studies suggest that glaciers of Ladakh mountains show an extremely different behavior as compared to the glaciers of rest of northwest Himalaya. Four glaciers, namely Durung Drung, Kangriz, Machoi and Siachen, representing the Indus and Shyok basin are dealt herein. Sufficient documentary and field evidences of these four glaciers support the view that glaciers housed in Ladakh mountains contradict the commonly accepted concept of fast melting glaciers in Himalaya (Ganjoo and Koul 2009; Ganjoo et al. 2010). The studies further suggest that the secular movement of glaciers in Ladakh mountains is a complex phenomena of several micro and macro-climatic factors, terrain morphology, and tectonics (Ganjoo 2009, Koul and Ganjoo 2010). The change in the morphology of glaciers is not necessarily related with the change in climate as commonly believed and hyped. Ganjoo, R.K. (2009) Holocene Tectonics and Climate of Durung Drung Glacier Basin, Zanskar Himalaya, India (Abstract). The 5th International Symposium on Tibetan Plateau and 24th Himalaya- Karakorum-Tibet Workshop, Aug. 11-14, Beijing, China. Ganjoo, R.K. and Koul, M.N. (2009) Is the Siachen glacier melting? Current Science, 97(3), 309-310. Ganjoo, RK; Koul, MN; Ajai; Bahuguna, IM (2010) Glaciers of Nubra valley, Karakorum mountains, Ladakh (India) vis-à-vis climate change (abstract). 7th Annual Meeting of Asia Oceania Geosciences Society, Hyderabad. Koul, M.N. and Ganjoo, R.K. (2010) Impact of inter- and intra-annual variation in weather parameters on mass balance and equilibrium line altitude of Naradu glacier (Himachal Pradesh), NW Himalaya, India. Climatic Change, 99, 119-139.
While it has been shown repeatedly that ocean conditions exhibit an important control on the behaviour of grounded tidewater glaciers, modelling studies have focused largely on the effects of basal and surface melting. Here, a finite-element model of stresses near the front of a tidewater glacier is used to investigate the effects of frontal melting on calving, independently of the calving criterion used. Applications of the stress model to idealized scenarios reveal that undercutting of the ice front due to frontal melting can drive calving at up to ten times the mean melt rate. Factors which cause increased frontal melt-driven calving include a strong thermal gradient in the ice, and a concentration of frontal melt at the base of the glacier. These properties are typical of both Arctic and Antarctic tidewater glaciers. The finding that frontal melt near the base is a strong driver of calving leads to the conclusion that water temperatures near the bed of the glacier are critically important to the glacier f...
Kääb, A.; Paul, F.; Huggel, C.; Kieffer, H.; Kargel, J.; Wessels, R.
Since the year 2000 imagery from ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer, on board TERRA) is available for observing global land ice. Its spectral and geometric properties include 3 bands in VNIR with 15m resolu- tion, 6 bands in SWIR with 30m, 5 bands in TIR with 90m, and a 15m-resolution NIR along-track stereo-band allowing for terrain height measurements. of special interest for glaciological studies are the high spatial resolution in VNIR, the stereo-, and the pointing-capabilities of ASTER. Here, we evaluate the benefit from ASTER data for glacier studies by accuracy assess- ments and application studies for test sites in the European Alps, New Zealand Alps and Himalayas: - ASTER-DEMs for high mountain environment are compared to ones derived from high-resolution aerial photogrammetry. - Multi-spectral glacier classification from ASTER data is compared to glacier map- ping from other high-resolution air- and space-borne sensors, such as aerial imagery and Landsat data. - The potential of repeated ASTER imagery for ice velocity measurements is demon- strated and evaluated using field measurements. - Combination of above techniques represents a powerful tool for assessing glacier- related hazards, as exemplified for glacier-lake outbursts and ice avalanches. The studies show that ASTER is indeed able to give new impulses for worldwide glacier monitoring (GLIMS-initiative). Its main limitation for that purpose might con- sist in the small swath width of 60km.
Large-scale atmosphere/ocean circulation and mountain glaciers represent two entirely different scales in the climate system. Therefore, statistical linkages between the two mask a cascade of processes that act on different temporal and spatial dimensions. Low-latitude glaciers are particularly well suited for studying such processes, since these glaciers are situated in the "heart" of the global climate system (the tropics). This presentation gives an overview of a decade of research on tropical climate and glaciers on Kilimanjaro (East Africa), which is, to our knowledge, the only case where space/time linkages between high-altitude glaciers and climate dynamics have been investigated systematically throughout the main scales. This includes the complex modification of atmospheric flow when air masses impinge on high mountains, an aspect that has been widely neglected from a cryospheric viewpoint. The case of Kilimanjaro demonstrates (1) the great potential of learning about climate system processes and their connections, (2) advances in our understanding of the importance of moisture for glaciers that lie far above the mean freezing level, and (3) methodological advances in combining atmospheric and cryospheric modelling.
Vallot, D.; Åström, J. A.; Schäfer, M.; Welty, E.; O'Neel, S.; Bartholomaus, T. C.; Liu, Y.; Riikilä, T.; Zwinger, T.; Timonen, J.; Moore, J.
The algoritm of a first principles calving-simulation computer-code is outlined and demonstrated. The code is particle-based and uses Newtonian dynamics to simulate ice-fracture, motion and calving. The code can simulate real-size glacier but is only able to simualte individual calving events within a few tens of minutes in duration. The code couples to the Elmer/Ice ice flow-simulation code: Elmer is employed to produce various glacier geomteries, which are then tested for stability using the particle code. In this way it is possible to pin-point the location of calving fronts. The particle simulation code and field observations are engaged to investigate the criticality of calving glaciers. The calving mass and inter-event waiting times both have power-law distributions with the same critical exponents as found for Abelian sand-pile models. This indicate that calving glaciers share characteristics with Self-Organized Critical systems (SOC). This would explain why many glacier found in nature may become unstable as a result of even minor changes in their environment. An SOC calving glacier at the critical point will display so large fluctuations in calving rate that it will render the concept 'average calving rate' more or less useless. I.e. 'average calving rate' will depend on measurement time and always have fluctuaions in the range of 100% more or less independent of the averaging time.
MacDonell, S.; Kinnard, C.; Mölg, T.; Nicholson, L.; Abermann, J.
Meteorological and surface change measurements collected during a 2.5 yr period are used to calculate surface mass and energy balances at 5324 m a.s.l. on Guanaco Glacier, a cold-based glacier in the semi-arid Andes of Chile. Meteorological conditions are marked by extremely low vapour pressures (annual mean of 1.1 hPa), strong winds (annual mean of 10 m s-1), shortwave radiation receipt persistently close to the theoretical site maximum during cloud-free days (mean annual 295 W m-2; summer hourly maximum 1354 W m-2) and low precipitation rates (mean annual 45 mm w.e.). Snowfall occurs sporadically throughout the year and is related to frontal events in the winter and convective storms during the summer months. Net shortwave radiation provides the greatest source of energy to the glacier surface, and net longwave radiation dominates energy losses. The turbulent latent heat flux is always negative, which means that the surface is always losing mass via sublimation, which is the main form of ablation at the site. Sublimation rates are most strongly correlated with net shortwave radiation, incoming shortwave radiation, albedo and vapour pressure. Low glacier surface temperatures restrict melting for much of the period, however episodic melting occurs during the austral summer, when warm, humid, calm and high pressure conditions restrict sublimation and make more energy available for melting. Low accumulation (131 mm w.e. over the period) and relatively high ablation (1435 mm w.e.) means that mass change over the period was negative (-1304 mm w.e.), which continued the negative trend recorded in the region over the last few decades.
Yong Zhang; Shiyin Liu; Junli Xu; Donghui Shangguan
Glaciers in the Tuotuo River basin, western China, have been monitored in recent decades by applying topographical maps and\\u000a high-resolution satellite images. Results indicate that most of glaciers in the Tuotuo River basin have retreated in the period\\u000a from 1968\\/1971 to 2001\\/2002, and their shrinkage area is 3.2% of the total area in the late 1960s. To assess the influence
Tamura, T; Williams, G D; Fraser, A D; Ohshima, K I
Variability in dense shelf water formation can potentially impact Antarctic Bottom Water (AABW) production, a vital component of the global climate system. In East Antarctica, the George V Land polynya system (142-150°E) is structured by the local 'icescape', promoting sea ice formation that is driven by the offshore wind regime. Here we present the first observations of this region after the repositioning of a large iceberg (B9B) precipitated the calving of the Mertz Glacier Tongue in 2010. Using satellite data, we find that the total sea ice production for the region in 2010 and 2011 was 144 and 134?km(3), respectively, representing a 14-20% decrease from a value of 168?km(3) averaged from 2000-2009. This abrupt change to the regional icescape could result in decreased polynya activity, sea ice production, and ultimately the dense shelf water export and AABW production from this region for the coming decades. PMID:22569370
Falkner, K. K.; Johnson, H. L.; Melling, H.; Muenchow, A.; Samelson, R. M.; Friends Of Petermann
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 be sporadic on a decadal timescale. Multiple factors likely contribute to calving events. These include the geometry of the fjord, absence of sea ice, preconditioning of the glacier by crevassing and melt related cracking and occurrence of strong katabatic or orographically channeled winds. The recent event falls within the realm of previously documented calving rates but the remaining tongue length is the shortest ever directly observed. Gaps in the 134 year record preclude final judgment about whether the recent calving is entirely unprecedented. Rising surface temperature trends and changed sea ice and ocean circulation patterns in the Arctic could render the tongue susceptible to collapse. As this could contribute to accelerated ice mass flux from Greenland, it is important to continue to observe and clarify processes operative in this system.
Goldin, Beatrice; Rudaz, Benjamin; Bardou, Eric
Climate changes can result in a wide range of variations of natural environment including retreating glaciers. Melting from glaciers will have a significant impact on the sediment transport characteristics of glacierized 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 basin located in the southern Walliser Alps (Switzerland) characterized by a complex glacier system with well-developed lateral moraines on glacier margins already crossed by several lateral channels. Glacier retreat of the main glacial edifice will provide a new connectivity pattern. At present the glacier 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 glacier 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 glacier 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 the rough surface of the SLBL results. The impact of sediment dynamic changes on the study catchment due to glacier retreat has been assessed by comparing predictions deriving from model application on different scenarios. Simulations allowed the analysis of sediment connectivity evolution over decade scales suggesting an increase of potential sediment transfer and connections in areas close to the main channel network. References: Cavalli, M., Trevisani, S., Comiti, F., Marchi, L., 2013. Geomorphometric assessment of spatial sediment connectivity in small Alpine catchments. Geomorphology 188, 31-41. Jaboyedoff M., Bardou E., Derron M.-H. 2004. Sloping local base level: a tool to estimate potential erodible volume and infilling alluvial sediment of glacial valleys. Swiss Geo-Scientists meeting, November 2004, Lausanne.
Gascoin, S.; Kinnard, C.; Ponce, R.; Lhermitte, S.; MacDonell, S.; Rabatel, A.
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).
Naz, B. S.; Frans, C. D.; Clarke, G. K. C.; Burns, P.; Lettenmaier, D. P.
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, Alberta, Canada. 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. We compare predicted variations in glacier extent, snow water equivalent (SWE), and streamflow discharge with satellite estimates of glacier area and terminus position, observed glacier mass balance, observed streamflow and snow water-equivalent measurements, respectively over the period of 1980-2007. Observations of multiple hydroclimatic variables compare well with those simulated with the coupled hydrology-glacier model. Our results suggest that, on average, the glacier melt contribution to the Bow River flow upstream of Lake Louise is approximately 22% in summer. For warm and dry years, however, the glacier melt contribution can be as large as 47% in August, whereas for cold years, it can be as small as 15% and the timing of the glacier melt signature can be delayed by a month. The development of this modeling approach sets the stage for future predictions of the influence of warming climate on streamflow in partially glacierized watersheds.
Yasuda, T.; Furuya, M.
Surge-type glaciers oscillate between long-quiescent phase and short-active phase (i.e. decades of slow flow and shorter periods of rapid flow). Surge-type glaciers are distributed around the world and cluster around specific region and it's believed that at least 1 % of world glacier caused surge. Direct observations are difficult due to decades surge cycle and remote situation. To identify surge-type glacier, surface structures, such as looped-moraine and maze-crevasse, are used alternatively. The mechanisms of glacier surges are still not understood completely but recent studies suggest that glacier surge is likely a result of changing hydrological and/or thermal conditions. Many mountain glaciers are developed in West Kunlun Shan (WKS) located in NW Tibetan plateau. Scherler et al. (2011) mentioned that unusual low velocities at frontal part were associated with past surges in WKS but there are no reports of spatio-temporal data of glacier surge, to our knowledge. We detected glacier surge and its velocity change in WKS. We used offset tracking method based on Synthetic Aperture Radar (SAR) data, assumed that glaciers flow parallel to surface topography derived from SRTM4 digital elevation model and converted offset-results to surface velocity field. Also, we detected glacier front change using SAR intensity images and Landsat optical images. We paid attention to 36 glaciers in WKS. Among 5 glaciers were obviously classified as surge-type glacier. Surface velocity of these glaciers gradually accelerated and decelerated, accompanied by advance of glacier terminus. For example, Chongce glacier on the south slope of WKS was active phase in 1990's. Surface velocity increased up to ~700m/year in 1996. No surge signal detected from 2003. Velocity profile of Chongce glacier dramatically changed. The upper part was ~20-30m/year but the lower part was ~0-5m/year. We detected same behavior at Zhongfeng glacier (branch 1) on the south slope. Except for Chongce glacier and Zhongfeng glacier (branch 1), many glaciers in WKS had stagnant flow and probably classified as surge-type glaciers. However, dead ice caused stagnant flow. Continuous monitoring is necessarily to elucidate entire surge cycle in WKS.
Zoet, L.; Iverson, N. R.
Glacier sliding laws exist in various forms and are applied in modeling of glacier dynamics. Sliding laws have been, in most cases, theoretically derived but not experimentally tested. Under certain conditions ice sliding over a rigid bed will generate cavities in the lees of bedrock bumps. These cavities will redistribute shear stress to regions of the bed that are in contact with ice. Sliding laws that incorporate cavity formation relate drag to the maximum adverse slope of the region of ice-bed contact. Sinusoidal and stepped-bed geometries are, therefore, predicted to affect basal drag differently. A sinusoidal bed is predicted to have a double-valued drag response as a function of sliding velocity, whereas the steady-state drag on a stepped bed with linear adverse slopes is expected to be independent of sliding velocity. We have conducted an experimental study of sliding laws using a ring shear apparatus that slides ice over a rigid bed. The device rotates a ring of ice that is 20 cm wide, 20 cm tall, with outer diameter of 90 cm. The sliding speed at the ice ring's centerline was incrementally stepped between 7.25--324 m/yr, and a vertical stress of 500 kPa was applied to the ice ring. The ice consisted initially of randomly oriented crystals that with sliding quickly developed a fabric like those observed in ice near glacier beds. The temperature of the ice is held at the pressure melting point and is regulated to ~0.01oC by a bath of circulating fluid that surrounds the sample chamber. Experiments have been conducted on a stepped bed with a constant slope of 8.3 and a sinusoidal bed with a wavelength of 183.3 mm and an amplitude of 15.3 mm. Water was allowed to drain from cavities, so effective stress at the bed was equal to the total vertical stress. Our experimental results differ from theoretical predictions. For the stepped bed, a decrease in shear stress of ~50% over a 12-fold increase in velocity is observed, in contrast to theoretical predictions of a constant shear stress. This rate weakening could be attributed to spatial variability in the rheological properties of the ice, or an unresolved three-dimensional effect. Rheological variability could result from steep gradients in deviatoric stress in ice as it moves from above the cavity to the bed. The results from the sinusoidal bed demonstrate a decrease in shear stress with increasing sliding velocity that is larger than with the stepped bed. Thus, the well-described theoretical effect of a sinusoidal bed on rate weakening is augmented by whatever effect is responsible for rate weakening with the stepped bed. These results provide the first experimental targets for models of sliding that attempt to assess effects of ice-bed separation.
The article tackles the issue of which factors may influence the flow direction and morphological shape of glacier tongues terminating at tributary junctions to the main valley in high mountain landscapes. A very particular morphological form of a glacier tongue shows the Jatunraju Glacier in the Cordillera Blanca (Perú). It terminates in the superior Parón Valley with a prominent crooked form, embedded in a 250 m-high moraine pedestal. Lliboutry (1977) has explained the deviation of the Jatunraju Glacier tongue as a result of a proglacial lake outburst. Alternative hypothetical models on a general scale have been developed for the causes determining the morphological characteristics of glacier tongues. These are based on empirical field evidence from the Parón Valley and from glaciers located in other high mountain areas, in particular in the Himalaya Region, where glacier tongues in confluence settings are abundant. The comparative investigations demonstrate that the pronounced crooked form of the Jatunraju Glacier may not be the result of a single extreme event, but may have been produced as well by gradual processes. In a general context, the study shows that crooked glacier tongues are common landforms in other mountain regions and mainly intrinsic to debris-covered glaciers. The morphological evolution of glacier tongues may involve a polygenetic process pattern over a longer geological time period. Apart from the steepness of the valley gradient of the main valley, the former confluence from the source glacier with the main glacier during times of a more extensive glaciation is regarded as one of the dominating factors controlling the later evolution of glacier tongues in general ("inherited confluence model").
Lilien, D.; Joughin, I. R.; Smith, B. E.
Glaciers along the Amundsen Coast are changing rapidly, which has drawn substantial scientific and public attention. Modeling and observation suggest warm-water intrusion and consequent melting as the cause of observed changes, and that unstoppable retreat may have already been triggered in some drainages. While Pine Island and Thwaites Glaciers are losing the most mass and have been the predominant objects study, other systems, particularly Smith, Pope and Kohler Glaciers and the corresponding Dotson and Crosson Shelves, are changing more rapidly relative to their size. Though smaller, these glaciers still have potentially large implications for overall regional dynamics as their beds connect below sea level to surrounding basins. In particular, the long, deep trough of Smith Glacier nearly links to the large eastern tributary of Thwaites, potentially causing rapid changes of Smith to have significant impact on the continuing retreat of Thwaites.We implemented a numerical model in Elmer/Ice, an open-source, full-Stokes, finite-element software package, to investigate the response of the Smith/Pope/Kohler system to different initial conditions. We use various parameterizations of sub-shelf melting with constant magnitude to examine the sensitivity of overall dynamics to melt distribution. Because melt distribution affects lateral buttressing and upstream grounded areas, it is potentially an important control on ice shelf and outlet glacier dynamics. Through comparison to the most recent velocity data, we evaluate the ability of differing melt parameterizations to reproduce the behavior currently seen in Smith/Pope/Kohler glaciers. In addition, we investigate the effect of using different years of velocity data with constant elevation input when initiating model runs. By comparing results over the satellite record to initiation with synchronous observations, we assess the accuracy of the often necessary practice of using differently timestamped datasets.
Phillips, E.; Molnia, B.
In 1909, USGS geologists U.S. Grant and D. F. Higgins mapped and photographed all of the tidewater glaciers and many of the land-terminating outlet glaciers in what is now Kenai Fjords National Park, creating a thorough record of glacier terminus positions and heights. In August, 2004, with funding from the National Park Service and the USGS Earth Surface Dynamics Program, we conducted a new photo survey in Grant and Higgins' footsteps. We re-established 40 of their photo stations with a confidence level of approximately 5-30 feet. We located the sites by identifying foreground features and by analyzing the extent of overlap of mountain peaks in the 1909 photo backgrounds. WAAS-enabled GPS was used to determine the location of each station for future surveys. At each station, we took new photographs duplicating the field of view shown in the 1909 photographs and also showing panoramic views. At most locations, the change in glacier height and terminus position since 1909 has been dramatic. At several stations, glacier termini were no longer visible. Northwestern Glacier, for example, has retreated around a series of bends in its valley. In some cases, vegetation completely obstructed the view from the 1909 photo station. In these instances, new GPS-located photo stations were established within sight of the present day termini. To illustrate the changes for the public, a dozen photographic pairs have been turned into animated GIFs using MacroMedia Flash. Each animation begins with a 1909 Grant and Higgins photograph which fades into the 2004 image. The two images have been correlated by matching topographic features. The animations clearly depict changes in vegetation, glacier cover, and geomorphologic features that have taken place in the last 95 years.
Godon, C.; Mugnier, J. L.; Fallourd, R.; Paquette, J. L.; Pohl, A.; Buoncristiani, J. F.
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.
Legchenko, A.; Vincent, C.; Baltassat, J. M.; Girard, J. F.; Thibert, E.; Gagliardini, O.; Descloitres, M.; Gilbert, A.; Garambois, S.; Chevalier, A.; Guyard, H.
Tête Rousse is a small polythermal glacier located in the Mont Blanc area (French Alps) at an altitude of 3100 to 3300 m. In 1892, an outburst flood from this glacier released about 200 000 m3 of water mixed with ice, causing much damage. A new accumulation of melt water in the glacier was not excluded. The uncertainty related to such glacier conditions initiated an extensive geophysical study for evaluating the hazard. Using three-dimensional surface nuclear magnetic resonance imaging (3-D-SNMR), we showed that the temperate part of the Tête Rousse glacier contains two separate water-filled caverns (central and upper caverns). In 2009, the central cavern contained about 55 000 m3 of water. Since 2010, the cavern is drained every year. We monitored the changes caused by this pumping in the water distribution within the glacier body. Twice a year, we carried out magnetic resonance imaging of the entire glacier and estimated the volume of water accumulated in the central cavern. Our results show changes in cavern geometry and recharge rate: in two years, the central cavern lost about 73% of its initial volume, but 65% was lost in one year after the first pumping. We also observed that, after being drained, the cavern was recharged at an average rate of 20 to 25 m3 d-1 during the winter months and 120 to 180 m3 d-1 in summer. These observations illustrate how ice, water and air may refill englacial volume being emptied by artificial draining. Comparison of the 3-D-SNMR results with those obtained by drilling and pumping showed a very good correspondence, confirming the high reliability of 3-D-SNMR imaging.
Sosio, Rosanna; Crosta, Giovanni B.; Chen, Joanna H.; Hungr, Oldrich
Ice-rock avalanches which occur in glacial environments are controlled by the presence of snow and ice in the moving material and by possible propagation onto icy basal surfaces. All these factors contribute to enhancing the flow mobility. Mixing with ice and snow hampers block collisions and favours dense flow behaviour. Ice melting reduces granular friction by saturation of the basal material and fluidization effects. Propagating onto glaciers offers a smooth surface with low shear resistance. This work is a review of the best documented ice-rock avalanches and focuses on evaluating their mobility for hazard analysis purposes by providing a set of calibrated cases. The rock avalanches have volumes ranging from 5*106 m3 to 25*106 m3. We replicate these events by using SPH and FEM numerical methods, assuming frictional and Voellmy basal rheologies. The Voellmy rheology best performs at replicating the landslide propagation. Among the back analyzed cases, the frictional coefficient ranges in the interval 0.03-0.1, the turbulent coefficient within 1000 m s-2-2000 m s-2. The bulk basal friction angle ranges within 2.75° and 14° with values inversely related to event volumes. Forward selection of the basal friction angle based on event volume, allows the replication of the Mount Cook ice-rock avalanche predicting a maximum runout which is less than 4% larger than observed. In the perspective of forward modelling, large uncertainty is related to the reconstruction of the post-event topographies, particularly for the sliding surface. Mixing with ice and snow reduces basal friction proportionally to ice and snow content. Pure ice has a basal friction which is reduced by about 75% than basal friction of pure rock. Melting of ice during rock avalanche propagation has been evaluated for the Sherman event. The frictional heat generated at the glacier surface results in the melting of 86.2 ± 5.9 kg m-2, which could have contributed to a minimum 20-35% (±10%) reduction of the material friction angle through the sole pore pressure generation within a 40 and 20 cm thick shear layer, respectively. The largest uncertainty is related to the area of contact between rock and ice.
Fountain, Andrew G.
, Portland, OR 97213, USA 3 North Cascade National Park, Sedro-Woolley, WA 98284, USA ABSTRACT. Benchmark to the glacier and to most parts on the glacier. This made field logistics much simpler and less expensive
Bajracharya, S. R.; Maharjan, S.; Shrestha, F.; Shrestha, B.; Wanqin, G.; Shiyin, L.; Xiaojun, Y.; Khattak, G. A.
In contrary to general glacier retreat in this vast Hindu Kush-Himalayan (HKH) region, some of the glaciers are advancing in the Karakorum (Hewitt, 1985). To understand the climate change impacts on glaciers, it is crucial to update the glacier status. The bigger concern in the HKH region, however, is the lack of long-term information on glaciers at the regional level for any kind of credible baseline or assessment of change. Hence to provide the up to date glacier information the glacier inventory was carried out using a single source satellite images of latest date so far possible. The present mapping of glaciers is the first effort of homogeneous glacier inventory of entire Hindu Kush-Himalayan region, which made the first time reporting of glaciers from Myanmar and first generation of glacier mapping and inventory of Afghanistan and Jammu & Kashmir and Arunachal states of India for ICIMOD. For Nepal, Bhutan, Pakistan, some states of India (Himachal, Uttarakhand and Sikkim) and Ganges basin in China will be the second generation glacier mapping and inventory of ICIMOD. The inventory is based on Landsat 7 ETM+ satellite images from 2005±3 years and SRTM DEM. The methodology of semi-automatic mapping and inventory is developed and implemented in the present study for quick delivery of glacier database. A first attempt is also made to map and deliver the Clean Ice and Debris Cover glaciers data separately. The glacier parameters like Glacier ID (Watershed and GLIMS), Area (Debris Cover and Clean Ice), Elevation, Slope, Aspect, Thickness, Ice reserve and 100m Glacier Area-Altitude bins are generated. The glaciers with sizes larger than 0.02 km2 are mapped. From the entire HKH region about 54,800 glaciers are mapped with about 60,400 km2 glacier area and 6,100 km3 estimated ice reserves. It was found that the average glacier area of the HKH region is 1.10 km2 per glacier (Bajracharya and others 2011).
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J. M. Hirose; S. J. Marshall
The climate and glacier changes in the Columbia Mountains is dissimilar to other high alpine regions in the Western Canadian Cordillera, and is less understood due to a scarcity of glaciological and hydro-meteorological information. The Illecillewaet Glacier (5.9 km2) in Glacier National Park, British Columbia is representative of the Columbia Mountain glaciers. We investigated in 2009 the spatial and temporal
R. Bhambri; T. Bolch; R. K. Chaujar
Mapping of debris-covered glaciers using remote-sensing techniques is recognized as one of the greatest challenges for generating glacier inventories and automated glacier change analysis. The use of visible (VIS) and near-infrared (NIR) bands does not provide sufficient continual information to detect debris-covered ice with remote-sensing data. This article presents a semi-automated mapping method for the debris-covered glaciers of the Garhwal
Dong, Zhiwen; Qin, Dahe; Chen, Jizu; Qin, Xiang; Ren, Jiawen; Cui, Xiaoqing; Du, Zhiheng; Kang, Shichang
This work discusses the temporal variation of various physicochemical species in the meltwater runoff of Laohugou Glacier No. 12 (4260 ma.s.l.) in central Asia, and their correlation with dust particles, based on a two-year field observation in summer 2012 and 2013, mainly focusing on dust concentration and size distribution, meltwater chemistry, particles SEM-EDX analysis in the meltwater, and MODIS atmospheric optical depth fields around the Qilian Mountains in central Asia. We find that, the volume-size distribution of dust particles in the meltwater is mainly composed of three parts, which includes fine aerosol particles (with diameter of 0~3.0 ?m, mainly PM 2.5), atmospheric dust (with diameter of 3.0~20 ?m), and local dust particles (20~100 ?m), respectively. Comparison of dust particles in the snowpack and meltwater runoff indicates that, large part of dust particles in the meltwater may have originated from atmospheric dust deposition to the snow and ice on the glacier, and transported into the meltwater runoff. Moreover, temporal variation of dust and major ions (especially crustal species) is very similar with each other, showing great influence of dust particles to the chemical constituents of the glacier meltwater. SPM and TDS implied significant influences of dust to the physical characteristics of the glacier meltwater. Results showed that, accelerated glacier melting may affect physicochemical characteristics of the meltwater at an alpine basin under global warming. MODIS atmospheric optical depth (AOD) fields derived using the Deep Blue algorithm, showed great influence of regional dust transportation over western Qilian Mountains in springtime. SEM-EDX analysis shows that dust particles in the glacier meltwater contain Si-, Al-, Ca-, K-, and Fe-rich materials, such as quartz, albite, aluminate, and fly ash, similar to that deposited in snowpack. These results showed great and even currently underestimated influences of atmospheric dust deposition to glacier meltwater physicochemistry at an alpine basin in central Asia. PMID:25010943
Manconi, Andrea; Dell'Anese, Federico; Giordan, Daniele; Allasia, Paolo; Curtaz, Michèle; Vagliasindi, Marco; Bertolo, Davide
Monitoring the spatial and temporal evolution of glaciers modifications in a climate change scenario is a major scientific problem. The Italian side of the Grandes Jorasses massif, Mont Blanc, is historically known for the occasional activation of icefalls events from the frontal part of the glaciers located on that area. The Planpincieux Glacier (PG) is a "polythermal" glacier, meaning that the liquid water present at the contact between ice and the bedrock in the lower part of the glacier itself plays an important role in its dynamics. Under these conditions icefalls might occur in a sudden and barely predictable manner. In this scenario, an accurate analysis of its morphological evolution is crucial; however, one of the major problems on PG is the limited access to perform direct measurements. For this reason, remote sensing has been identified as the more convenient approach to achieve quantitative measurements of surficial modifications. An experimental monitoring station was installed on August 2013 in order to monitor the surface displacements at PG. The monitoring station is located on the opposite side of the valley, at the top of the Mt. de la Saxe, ca. 3.5 km away from the target under investigation. Monitoring includes: (i) a surveillance module, based on a medium resolution digital camera, observing large part of the slope; (ii) a photogrammetric module, based on a high resolution digital camera equipped with a 300 mm optical zoom, pointed to the PG front. Digital images acquired by the monitoring station are acquired with a revisit time of 1-hour, and analyzed by considering change-detection and pixel-offset techniques. This approach allows to evaluate surface changes over time, as well as to retrieve quantitative measurements of the glacier displacements. Here we present the results after one year of monitoring, and we discuss how the combination of different remote sensing techniques can be exploited for a better understanding of the glacier dynamics.
Beckmann, Johanna; Siegrfied, Merten; Perrette, Mahé; Carlov, Reinhard; Ganopolski, Andrey
Over the last few decades Greenland ice mass loss has strongly increased due to surface melt and dynamic changes in marine-terminating outlet glaciers. A major reason for the retreat of these glaciers is believed to be related to increased submarine melting, which in turn is caused by surrounding ocean warming and the enhanced subglacial water discharge. These complex physical processes are not yet fully understood. Inspecting the sensitivities of submarine melting to model formulation and model parameters is crucial for investigations of outlet glacier response to future climate change. Different approaches have been used to compute submarine melt rates of outlet glaciers using experimental data, numerical modelling and simplified analytical solutions. To model the process of submarine melting for a selection of Greenland outlet glaciers, a simple submarine melt parameterization is incorporated into a one-dimensional dynamic ice-flow model. The behaviour of this submarine melt parameterization is demonstrated by running a suite of simulations to investigate the sensitivity of submarine melt to changes in ocean properties and the amount and distribution of subglacial water discharge. A comparison of the simple parameterization with three-dimensional models and experimental data is conducted to assess the quality of parameterization and improve the parameterization of submarine melting.
Cook, S.; Rutt, I. C.; Murray, T.; Luckman, A.; Selmes, N.; Goldsack, A.; Zwinger, T.
Calving is an important mass-loss process for many glaciers worldwide, and has been assumed to respond to a variety of environmental influences. We present a grounded, flowline tidewater glacier model, using a physically realistic calving mechanism, which is applied to Helheim Glacier, East Greenland. By qualitatively examining both modelled size and frequency of calving events, and the subsequent dynamic response, the model is found to produce a realistic representation of calving behaviour. Experiments use four environmental variables which have been suggested to affect calving rates: water depth in crevasses, basal water pressure, undercutting of the calving face by submarine melt and backstress from ice mélange. Of the four variables, only crevasse water depth and basal water pressure were found to have a significant effect on terminus behaviour when applied at a realistic magnitude. These results are in contrast to previous modelling studies, which have suggested that ocean temperatures could strongly influence the calving front. The results raise the possibility that Greenland outlet glaciers could respond more strongly than previously thought to the recent trend of increased surface melt observed in Greenland, as surface ablation can strongly affect water depth in crevasses and water pressure at the glacier bed.
Schütte, Ursel M.E.; Abdo, Zaid; Bent, Stephen J.; Williams, Christopher J.; Schneider, G. Maria; Solheim, Bjørn; Forney, Larry J.
Succession is defined as changes in biological communities over time. It has been extensively studied in plant communities, but little is known about bacterial succession, in particular in environments such as High Arctic glacier forelands. Bacteria carry out key processes in the development of soil, biogeochemical cycling, and facilitating plant colonization. In this study we sampled two roughly parallel chronosequences in the foreland of Midre Lovén glacier on Svalbard, Norway and tested whether any of several factors were associated with changes in the structure of bacterial communities, including time after glacier retreat, horizontal variation caused by the distance between chronosequences, and vertical variation at two soil depths. The structures of soil bacterial communities at different locations were compared using terminal restriction fragment length polymorphisms (T-RFLP) of 16S rRNA genes, and the data were analyzed by sequential analysis of log-linear statistical models. While no significant differences in community structure were detected between the two chronosequences, statistically significant differences between sampling locations in the surface and mineral soils could be demonstrated even though glacier forelands are patchy and dynamic environments. These findings suggest bacterial succession occurs in High Arctic glacier forelands but may differ in different soil depths. PMID:19587774
Schütte, Ursel M E; Abdo, Zaid; Bent, Stephen J; Williams, Christopher J; Schneider, G Maria; Solheim, Bjørn; Forney, Larry J
Succession is defined as changes in biological communities over time. It has been extensively studied in plant communities, but little is known about bacterial succession, in particular in environments such as High Arctic glacier forelands. Bacteria carry out key processes in the development of soil, biogeochemical cycling and facilitating plant colonization. In this study we sampled two roughly parallel chronosequences in the foreland of Midre Lovén glacier on Svalbard, Norway and tested whether any of several factors were associated with changes in the structure of bacterial communities, including time after glacier retreat, horizontal variation caused by the distance between chronosequences and vertical variation at two soil depths. The structures of soil bacterial communities at different locations were compared using terminal restriction fragment length polymorphisms of 16S rRNA genes, and the data were analyzed by sequential analysis of log-linear statistical models. Although no significant differences in community structure were detected between the two chronosequences, statistically significant differences between sampling locations in the surface and mineral soils could be demonstrated even though glacier forelands are patchy and dynamic environments. These findings suggest that bacterial succession occurs in High Arctic glacier forelands but may differ in different soil depths. PMID:19587774
Slayback, D. A.; Yager, K.; Baraer, M.; Mohr, K. I.; Argollo, J.; Wigmore, O.; Meneses, R. I.; Mark, B. G.
Montane peatbogs in the glacierized Andean highlands of Peru and Bolivia provide critical forage for camelids (llama and alpaca) in regionally extensive pastoral agriculture systems. During the long dry season, these wetlands often provide the only available green forage. A key question for the future of these peatbog systems, and the livelihoods they support, is the impact of climate change and glacier recession on their hydrology, and thus forage production. We have already documented substantial regional glacier recession, of, on average, approximately 30% of surface area over the past two decades. As glaciers begin to retreat under climate change, there is initially a period of increased meltwater outflow, culminating in a period of "peak water", and followed by a continual decline in outflows. Based on previous work, we know that some glaciers in the region have already passed peak water conditions, and are now declining. To better understand the impacts of these processes on peatbog hydrology and productivity, we have begun collecting a variety of surface data at several study sites in both Bolivia and Peru. These include precipitation, stream flow, water levels, water chemistry and isotope analyses, and peatbog biodiversity and biomass. These measurements will be used in conjunction with a regional model driven by satellite data to predict likely future impacts. We will present the results from these initial surface measurements, and an overview of satellite datasets to be used in the regional model.
Stearns, L. A.; Foga, S. C.; Hamilton, G. S.; Straneo, F.; Sutherland, D.; van der Veen, C. J.; Oltmanns, M.; Schild, K. M.
Iceberg calving is an efficient mechanism for ice mass loss. While the physical controls on calving are not well understood, recent field and remote sensing observations from Helheim Glacier, southeast Greenland, suggest calving is dependent on both glacier and fjord conditions. This presentation investigates the sensitivity of calving rates to ice velocity, ocean temperature and mélange composition using a combination of in situ and satellite observations. Ocean properties in Sermilik Fjord for 2009-2014 are reconstructed using mooring data, and an object-based image analysis (OBIA) that inventories icebergs, sea-ice and small icebergs quantifies mélange composition several times a season. Ice velocity from InSAR and optical imagery is used to calculate calving rates and investigate the role of longitudinal gradients on calving. Ice velocity appears to be the dominant control on calving rates at Helheim Glacier. However, calving rates exhibit a complex pattern of seasonal and interannual variability, which does not simply mimic ice velocity patterns. We explore the relative roles of ocean properties, glacier geometry, and mélange composition on calving rates from 2001-2014 in order to improve physically-based glacier models.
Y. Ahn; I. M. Howat
Remote sensing from space has enabled effective monitoring of remote and inhospitable polar regions. Glacier velocity, and its variation in time, is one of the most important parameters needed to understand glacier dynamics, glacier mass balance and contribution to sea level rise. Regular measurements of ice velocity are possible from large and accessible satellite data set archives, such as ASTER
Seamons, Kent E.
Quantification of glacier melt volume in the Indus River watershed Maria Nicole Asay A thesis;ABSTRACT Quantification of glacier melt volume in the Indus River watershed Maria N. Asay Department is applied to glaciers in the Indus River watershed located in Afghanistan, China, India, and Pakistan. Here
Paris-Sud XI, Université de
ATTEMPT OF ALPINE GLACIER FLOW MODELING BASED ON CORRELATION MEASUREMENTS OF HIGH RESOLUTION SAR TerraSAR-X SAR images and a Digital Elevation Model. First, a glacier flow model is established the glacier obtained from the sub-pixel image corre- lation of a series of TerraSAR-X SAR images is used
Creep of Two Alpine Rock Glaciers Observation and Modelling (Ötztal- and Stubai Alps, Austria), Wolfram Mostler (Innsbruck) Abstract Our study concentrates on two active rock glaciers in the Eastern) measurements. The structure of these rock glaciers was also explored by geophysical methods (GPR, refraction
Kansas, University of
an ice shelf is afloat in the ocean, its removal does not change sea level, but it may affect glacierRecent ice loss from the Fleming and other glaciers, Wordie Bay, West Antarctic Peninsula E. Rignot ice thickness data from 2002, reveal that the glaciers flowing into former Wordie Ice Shelf, West
1 Modeling Support for National Park Planning: Initial Results from Glacier National Park Andrew. The main case study simulates operational issues at Glacier National Park. The model simulates vehicles is used to show the simulated impacts from the park's shuttle system. The Glacier study demonstrates
J. Foght; J. Aislabie; S. Turner; C. E. Brown; J. Ryburn; D. J. Saul; W. Lawson
Viable prokaryotes have been detected in basal sediments beneath the few Northern Hemisphere glaciers that have been sampled for microbial communities. However, parallel studies have not previously been conducted in the Southern Hemisphere, and subglacial environments in general are a new and underexplored niche for microbes. Unfrozen subglacial sediments and overlying glacier ice samples collected aseptically from the Fox Glacier
Tsai, Victor C.
Ice-front variation and tidewater behavior on Helheim and Kangerdlugssuaq Glaciers, Greenland Ian Glaciers, Greenland, from 2001 to 2006, a period in which they retreated and sped up. These data show and retreat in less than a century indicates that tidewater glaciers in Greenland can advance rapidly
Howat, Ian M.
Changes in the Dynamics of Marine-Terminating Outlet Glaciers in West Greenland (2000-2009) 1 2 3 of Greenland's marine-terminating outlet glaciers indicate a rapid and complex response to external forcing Greenland's northwestern margin, it is unclear whether west Greenland glaciers have undergone
F. Paul; A. Kaeaeb; M. Maisch
The new Swiss Glacier Inventory for the year 2000 (SGI 2000) is presently derived from Landsat TM data. Glacier areas were obtained by segmentation of a ratio image from TM band 4 and 5. The accuracy of this method is assessed by comparing the TM derived glacier areas with those derived manually from higher resolution data sets, such as SPOT
Howat, Ian M.
Thirty-year history of glacier melting in the Nepal Himalayas Koji Fujita,1 Lonnie G. Thompson,2 of glacier melting in the Nepal Himalayas, J. Geophys. Res., 111, D03109, doi:10.1029/2005JD005894. 1. Introduction  Rapid shrinkage of glaciers in the Nepal Himalayas has been observed during recent decades [e
Johannes Koch; John J. Clague; Gerald D. Osborn
The Little Ice Age glacier history in Garibaldi Provincial Park (southern Coast Mountains, British Columbia) was reconstructed using geomorphic mapping, radiocarbon ages on fossil wood in glacier forefields, dendrochronology, and lichenometry. The Little Ice Age began in the 11th century. Glaciers reached their first maximum of the past mil- lennium in the 12th century. They were only slightly more extensive
Jaapjan Zeeberg; Steven L. Forman
Glacier retreat on north Novaya Zemlya for the past century was documented by registering glacier terminus positions from expedition and topographic maps and remotely sensed images. Recession of tidewater calving glaciers on north Novaya Zemlya in the first half of the twentieth century was relatively rapid (>300 m yr-1), consistent with post-‘Little Ice Age’ warming documented by a 122-year instrumental
C. Huggel; A. Kääb; N. Salzmann; W. Haeberli; F. Paul
Glacier-related hazards such as ice avalanches and glacier lake outbursts can pose a significant threat to population and installations in high mountain regions. They are well documented in the Swiss Alps and the high data density is used to build up sys- tematic knowledge of glacier hazard locations and potentials. Experiences from long research activities thereby form an important basis
...Off-road vehicle use in Glacier Bay National Preserve. 13.1109 Section 13.1109 ...Regulations-Glacier Bay National Park and Preserve Administrative Provisions § 13...Off-road vehicle use in Glacier Bay National Preserve. The use of off-road...
...Off-road vehicle use in Glacier Bay National Preserve. 13.1109 Section 13.1109 ...Regulations-Glacier Bay National Park and Preserve Administrative Provisions § 13...Off-road vehicle use in Glacier Bay National Preserve. The use of off-road...
...Off-road vehicle use in Glacier Bay National Preserve. 13.1109 Section 13.1109 ...Regulations-Glacier Bay National Park and Preserve Administrative Provisions § 13...Off-road vehicle use in Glacier Bay National Preserve. The use of off-road...
Nawri, Nikolai; Nína Petersen, Guðrún; Bjornsson, Halldór; Hahmann, Andrea N.; Jónasson, Kristján; Bay Hasager, Charlotte; Clausen, Niels-Erik
While Iceland has an abundant wind energy resource, its use for electrical power production has so far been limited. Electricity in Iceland is generated primarily from hydro- and geothermal sources, and adding wind energy has so far not been considered practical or even necessary. However, wind energy is becoming a more viable option, as opportunities for new hydro- or geothermal power installations become limited. In order to obtain an estimate of the wind energy potential of Iceland, a wind atlas has been developed as part of the joint Nordic project 'Improved Forecast of Wind, Waves and Icing' (IceWind). Downscaling simulations performed with the Weather Research and Forecasting (WRF) model were used to determine the large-scale wind energy potential of Iceland. Local wind speed distributions are represented by Weibull statistics. The shape parameter across Iceland varies between 1.2 and 3.6, with the lowest values indicative of near-exponential distributions at sheltered locations, and the highest values indicative of normal distributions at exposed locations in winter. Compared with summer, average power density in winter is increased throughout Iceland by a factor of 2.0 - 5.5. In any season, there are also considerable spatial differences in average wind power density. Relative to the average value within 10 km of the coast, power density across Iceland varies between 50 - 250%, excluding glaciers, or between 300 - 1500 W m-2 at 50 m above ground level in winter. At intermediate elevations of 500 - 1000 m above mean sea level, power density is independent of the distance to the coast. In addition to seasonal and spatial variability, differences in average wind speed and power density also exist for different wind directions. Along the coast in winter, power density of onshore winds is higher by 100 - 700 W m-2 than that of offshore winds. The regions with the highest average wind speeds are impractical for wind farms, due to the distances from road infrastructure and the power grid, as well as due to the harsh winter climate. However, even in easily accessible regions, wind energy potential in Iceland, as measured by annual average power density, is among the highest in Western Europe. Based on these results, 14 test sites were selected for more detailed analyses using the Wind Atlas Analysis and Application Program (WAsP). These calculations show that a modest wind farm of ten medium size turbines would produce more energy throughout the year than a small hydro power plant, making wind energy a viable additional option.
Sen Gupta, A.; Tarboton, D. G.; Racoviteanu, A.; Brown, M. E.; Habib, S.
This study enhances an energy balance snowmelt model (Utah Energy Balance, UEB) to include the capability to quantify glacier melt. To account for clean and debris covered glaciers, substrate albedo and glacier outlines determined from remote sensing, are taken as inputs. The model uses the surface energy balance to compute the melting of seasonal snow and glacier substrate once the seasonal snow has melted. In this application the model was run over a 360 km2 glacierized watershed, Langtang Khola, in the Nepal Himalaya for a 10-year simulation period starting in water year 2003. The model was run on a distributed mesh of grid cells providing the capability to quantify both timing and spatial variability in snow and glacier melt. The distributed UEB melt model has a relatively high data demand, while the Hindu-Kush Himalayan region is a data-scarce region, a limitation that affects most water resources impact studies in this region. In this study, we determined model inputs from the Modern Era Retrospective-Analysis for Research and Applications (MERRA) and Southern Asia Daily Rainfall Estimate (RFE2) data products. The model estimates that roughly 57% of total surface water input is generated from glacier melt, while snowmelt and rain contribute 34% and 9%, respectively over the simulation period. The melt model provided input to the USGS Geospatial Stream Flow Model (GeoSFM) for the computation of streamflow and produced reasonable streamflow simulations at daily scale with some discrepancies, while monthly and annual scale comparisons resulted in better agreement. The result suggests that this approach is of interest for water resources applications where monthly or longer scale streamflow estimates are needed. Mean annual streamflow was positively correlated with the total annual surface water input. However, mean annual streamflow was not correlated with total annual precipitation, highlighting the importance of energy balance melt calculation, in comparison to just using precipitation when considering streamflow availability. Overall, for a 10-year model run, the water equivalent of snow accumulation is 2.46 m compared to 7.13 m of glacier melt over the basin, suggesting a net loss in glacier mass.
Wagnon, Patrick; Linda, Anurag; Arnaud, Yves; Kumar, Rajesh; Sharma, Parmanand; Vincent, Christian; Pottakkal, Jose George; Berthier, Etienne; Ramanathan, Alagappan; Hasnain, Syed Iqbal; Chevallier, Pierre
Little is known about the Himalayan glaciers, although they are of particular interest in terms of future water supply, regional climate change and sea-level rise. In 2002, a long-term monitoring programme was started on Chhota Shigri Glacier (32.2°N, 77.5°E; 15.7 km2, 6263-4050 m a.s.l., 9 km long) located in Lahaul and Spiti Valley, Himachal Pradesh, India. This glacier lies in the monsoon-arid transition zone (western Himalaya) which is alternately influenced by Asian monsoon in summer and the mid-latitude westerlies in winter. Here we present the results of a 4 year study of mass balance and surface velocity. Overall specific mass balances are mostly negative during the study period and vary from a minimum value of -1.4 m w.e. in 2002/03 and 2005/06 (equilibrium-line altitude (ELA) ˜5180 m a.s.l.) to a maximum value of +0.1 m w.e. in 2004/05 (ELA 4855 m a.s.l.). Chhota Shigri Glacier seems similar to mid-latitude glaciers, with an ablation season limited to the summer months and a mean vertical gradient of mass balance in the ablation zone (debris-free part) of 0.7 m w.e. (100 m)-1, similar to those reported in the Alps. Mass balance is strongly dependent on debris cover, exposure and the shading effect of surrounding steep slopes.
Csatho, Beata; vanderVeen, Kees; Schenk, Toni
Repeat surveys by airborne laser altimetry in the 1990s have revealed significant thinning of outlet glaciers draining the interior of the Greenland Ice Sheet, with thinning rates up to several meters per year. To fully appreciate the significance of these recent glacier changes, the magnitude of retreat and surface lowering must be placed within the broader context of the retreat since the Last Glacial Maximum and, more significantly, of the retreat following the temporary glacier advance during the Little Ice Age (LIA). The LIA maximum stand is marked by trimlines, sharp boundaries between recently deglacifated unvegetated rocks, and vegetated surfaces at higher elevations. The objective of this project was to demonstrate the use of remote sensing data to map these trimlines and other glacial geomorphologic features.
Menounos, Brian; Koch, Johannes; Osborn, Gerald; Clague, John J.; Mazzucchi, David
Terrestrial and lake sediment records from several sites in the southern Coast Mountains, British Columbia, provide evidence for an advance of alpine glaciers during the early Holocene. Silty intervals within organic sediments recovered from two proglacial lakes are bracketed by AMS 14C-dated terrestrial macrofossils and Mazama tephra to 8780-6730 and 7940- 6730 14C yr BP [10,150-7510 and 8990- 7510 cal yr BP]. Radiocarbon ages ranging from 7720 to 7380 14C yr BP [8630- 8020 cal yr BP] were obtained from detrital wood in recently deglaciated forefields of Sphinx and Sentinel glaciers. These data, together with previously published data from proglacial lakes in the Canadian Rockies, imply that glaciers in western Canada advanced during the early Holocene. The advance coincides with the well-documented 8200-yr cold event identified in climate proxy data sets in the North Atlantic region and elsewhere.
The double phase liquid argon time projection chamber is an exciting new technology for neutrino detectors. This technology is known to provide excellent tracking and calorimetry performance that can outperform other techniques. In this context GLACIER is a proposed giant double phase liquid argon underground neutrino observatory scalable to masses of 100 kton. As proposed by the future European Long Baseline Neutrino Oscillation program (LBNO), a neutrino beam from CERN with GLACIER as far detector would allow to precisely measure the neutrino mixing parameters, determine the neutrino mass hierarchy and test the existence of the CP-violating phase. At the same time, the detector could conduct astroparticle experiments of unprecedented sensitivity. GLACIER relies on novel technologies which are currently being tested on small scale prototypes. In the near future, we also plan to construct and operate larger devices.
Falkner, Kelly K.; Melling, Humfrey; Münchow, Andreas M.; Box, Jason E.; Wohlleben, Trudy; Johnson, Helen L.; Gudmandsen, Preben; Samelson, Roger; Copland, Luke; Steffen, Konrad; Rignot, Eric; Higgins, Anthony K.
On 4 August 2010, about one fifth of the floating ice tongue of Petermann Glacier (also known as “Petermann Gletscher”) in northwestern Greenland calved (Figure 1). The resulting “ice island” had an area approximately 4 times that of Manhattan Island (about 253±17 square kilometers). The ice island garnered much attention from the media, politicians, and the public, who raised concerns about downstream implications for shipping, offshore oil and gas operations, and possible connections to Arctic and global warming. Does this event signal a change in the glacier's dynamics? Or can it be characterized as part of the glacier's natural variability? Understanding the known historical context of this event allows scientists and the public to judge its significance.
Satellite radar interferometry is a powerful technique to measure the surface velocity and topography of glacier ice. On ice shelves, a quadruple difference technique separates tidal motion from the steady creep flow deformation of ice. The results provide a wealth of information about glacier grounding lines , mass fluxes, stability, elastic properties of ice, and tidal regime. The grounding line, which is where the glacier detaches from its bed and becomes afloat, is detected with a precision of a few tens of meters. Combining this information with satellite radar altimetry makes it possible to measure glacier discharge into the ocean and state of mass balance with greater precision than ever before, and in turn provide a significant revision of past estimates of mass balance of the Greenland and Antarctic Ice Sheets. Analysis of creep rates on floating ice permits an estimation of basal melting at the ice shelf underside. The results reveal that the action of ocean water in sub-ice-shelf cavities has been largely underestimated by oceanographic models and is the dominant mode of mass release to the ocean from an ice shelf. Precise mapping of grounding line positions also permits the detection of grounding line migration, which is a fine indicator of glacier change, independent of our knowledge of snow accumulation and ice melting. This technique has been successfully used to detect the rapid retreat of Pine Island Glacier, the largest ice stream in West Antarctica. Finally, tidal motion of ice shelves measured interferometrically provides a modern, synoptic view of the physical processes which govern the formation of tabular icebergs in the Antarctic.
Marshall, S. J.
Observations of high-elevation meteorological conditions, glacier mass balance, and glacier runoff are sparse in western Canada and the Canadian Rocky Mountains, leading to uncertainty about the importance of glaciers to regional water resources. This needs to be quantified so that the impacts of ongoing glacier recession can be evaluated with respect to alpine ecology, hydroelectric operations, and water resource management. I assess the seasonal evolution of glacier runoff in an alpine watershed on the continental divide in the Canadian Rocky Mountains. Analysis is based on meteorological, snowpack and surface energy balance data collected at Haig Glacier from 2002-2013. The study area is one of several glacierized headwaters catchments of the Bow River, which flows eastward to provide an important supply of water to the Canadian prairies. Annual specific discharge from snow- and ice-melt on Haig Glacier averaged 2350 mm water equivalent (w.e.) from 2002-2013, with 42% of the runoff derived from melting of glacier ice and firn, i.e. water stored in the glacier reservoir. This is an order of magnitude greater than the annual specific discharge from non-glacierized parts of the Bow River basin. From 2002-2013, meltwater derived from the glacier storage was equivalent to 5-6% of the flow of the Bow River in Calgary in late summer and 2-3% of annual discharge. The basin is typical of most glacier-fed mountains rivers, where the modest and declining extent of glacierized area in the catchment limits the glacier contribution to annual runoff.
Marshall, S. J.
Observations of high-elevation meteorological conditions, glacier mass balance, and glacier run-off are sparse in western Canada and the Canadian Rocky Mountains, leading to uncertainty about the importance of glaciers to regional water resources. This needs to be quantified so that the impacts of ongoing glacier recession can be evaluated with respect to alpine ecology, hydroelectric operations, and water resource management. In this manuscript the seasonal evolution of glacier run-off is assessed for an alpine watershed on the continental divide in the Canadian Rocky Mountains. The study area is a headwaters catchment of the Bow River, which flows eastward to provide an important supply of water to the Canadian prairies. Meteorological, snowpack, and surface energy balance data collected at Haig Glacier from 2002 to 2013 were analysed to evaluate glacier mass balance and run-off. Annual specific discharge from snow- and ice-melt on Haig Glacier averaged 2350 mm water equivalent from 2002 to 2013, with 42% of the run-off derived from melting of glacier ice and firn, i.e. water stored in the glacier reservoir. This is an order of magnitude greater than the annual specific discharge from non-glacierized parts of the Bow River basin. From 2002 to 2013, meltwater derived from the glacier storage was equivalent to 5-6% of the flow of the Bow River in Calgary in late summer and 2-3% of annual discharge. The basin is typical of most glacier-fed mountain rivers, where the modest and declining extent of glacierized area in the catchment limits the glacier contribution to annual run-off.
Li, Zhongqin; Li, Huilin; Wang, Feiteng
Mountain glaciers are not only indicator of climate change, but also important water resources for oases and for the sustainable development of the ecological environment, industry and agriculture. However, due to climate warming, most of glaciers are in a state of rapid retreating. Altay Mountains, located in the border of China, Russia and Mongolia, foster the highest latitude glaciated region in China, providing important water resources for local economic development and people living. However, research on glacier change is limited in the Altay Mountains. Taking this into account, based on topographic maps in 1959, ASTER remote sensing data in 2008 and digital elevation models (DEMs), glacier changes in the Altay Mountains including glacier area, length, thickness and volume changes were analyzed in the support of 3S technology. Results showed that the total area and number of 226 glaciers investigated have reduced by 32.5% and 27.9% from 1959 to 2008. The average area reduction rate of glaciers with size <1 km2 and in 1-5 km2 is -66.7% and 27.9%, respectively. The reduction rate is more than 70% for the glaciers with size less than 0.5 km2. Glaciers have retreated by 253 m with the reduction rate of 18.3%. Furthermore, for 58 selected glaciers in the Youyi Area, the mean ice elevation decrease by 24.12 m with the volume loss of 2.649 km3, corresponding to the annual glacier runoff of 4.88×106 m3 during 1959-2008. Analysis indicated that the relative area reductions of small glaciers were usually higher than those of large ones, which exhibited larger absolute loss, indicating that the small glaciers were more sensitive to climate change than large ones. Glacier changes exhibited obvious spatial differences, indicating that the reduction rate of glaciers in the south slope of the Youyi Area was larger than in the north.
Uglietti, Chiara; Zapf, Alexander; Szidat, Sönke; Salazar, Gary; Hardy, Doug; Schwikowski, Margit
Interpreting climate signals contained in natural archives requires a precise chronology. Radiocarbon analysis can be a powerful tool for dating high-altitude ice cores, especially for the lowermost segments for which ice flow-induced thinning limits the counting of annual layers. Radiocarbon dating has been applied to ice cores containing sufficient organic material, which is a limiting factor to the wider application of this technique. We present a novel radiocarbon dating approach using carbonaceous aerosols enclosed in the ice to help resolve the debate about the age of the Kilimanjaro's plateau glaciers. Paleoclimate reconstructions based on six ice cores drilled in 2000 assigned a basal age of 11'700 years. A recent study claims recurring cycles of waxing and waning controlled primarily by atmospheric moisture and an absence of the ice bodies was suggested for 1200 AD. The Kilimanjaro ice fields are subject to rapid areal shrinkage and thinning and are expected to disappear within several decades. Resolving the controversy of the time frame for the extinction of the Kilimanjaro ice might have wide implications for the understanding of the natural climate variability in the tropics. A stratigraphic sequence of samples from the exposed vertical ice cliffs at the margins of the Northern Ice Field (NIF) was collected in 2011. A total of 45 horizontal short cores (50 cm length) were extracted from 22 horizons characterized by varying micro-particle concentrations. Additionally, 3 samples were taken from the glacier surface to investigate a potential age offset. All samples were shipped frozen to Paul Scherrer Institute, decontaminated in a cold room by removing the outer layer (0.3 mm) and by rinsing the samples with ultra-pure water. The insoluble carbonaceous particles were filtrated by using freshly preheated quartz fibre filters. Procedural blanks were estimated using artificial ice blocks of frozen ultra-pure water treated as real ice samples and were consistent with previously reported blanks. The combustion of the filters was conducted by means of a thermo-optical OC/EC analyser (Model4L, Sunset Laboratory Inc, USA), using a well-established protocol (Swiss 4S) for OC/EC separation. Analyses of 14C were conducted using the compact radiocarbon AMS system 'MICADAS' equipped with a gas ion source, directly coupled to the Sunset instrument. Conventional 14C ages were calibrated using OxCal v4.2.4 software with the SHCal13 calibration curve. The results of 14C calibrated ages for the South and North cliffs of the Kilimanjaro NIF span between modern ages on surface to 1200 AD at the bottom. Our 14C analyses results support the hypothesis that the ice on Kilimanjaro's plateau has come and gone repeatedly throughout the Holocene and have an age which differs considerably from the ice core assigned basal age of 11'700 years. It is possible that the cores collected further from the margin of the NIF contained older ice which is not present at the margins. If this is the case, the older ice must be relict, implying one or more long hiatuses, and a non-continuous record. Therefore, further investigations are necessary.
From balance to imbalance: a shift in the dynamic behaviour of Chhota Shigri glacier, western Toulouse Cedex, France ABSTRACT. Mass-balance and dynamic behaviour of Chhota Shigri glacier, western89. During the period 200210, the glacier experienced a negative glacier-wide mass balance of 0.67 Æ 0.40 m
Thomson, L.; Osinski, G.
As documented in the IPCC's Climate Change 2007 report, the high latitude regions of the Northern Hemisphere are experiencing the highest rates of warming. Given that 35% of the global glacial ice exists within the Arctic Archipelago, this region provides an excellent laboratory for monitoring the anticipated degree of glacial recession . Evidence of arctic warming through negative mass balance trends has been detected in several studies already [e.g., 2]. Here, we show the importance and value of historical records in the task of monitoring glacial retreat. A highly detailed inventory developed by S. Ommanney in 1969 , has been revisited and transformed into digital format for the purposes of integration with modern inventories. The Ommanney inventory covers the entirety of Axel Heiberg Island , NU, and includes details often lacking in present day inventories, including orientations (accumulation and ablation zones), elevations (highest, lowest, elevation of the snowline, and the mean elevations of both the accumulation and ablation areas), length (of the ablation area, exposed ice, and of the total glacier including debris cover), area (of the ablation area, exposed ice, and of the total glacier), accumulation area ratio (AAR), depth, volume, and a six digit code which gives qualitative details on glacier attributes. This report is one of the most thorough and comprehensive glacier inventory report ever published in Canada. More recent inventories used for comparison include the glacier extents created by the National Topographic System based on photography from 1980-1987, as well as extents developed by Dr. Luke Copland for the Global Land Ice Measurements from Space (GLIMS) database using 1999-2000 satellite imagery. Our preliminary results show that approximately 90% of ice bodies under 0.2km on Axel Heiberg Island have disappeared entirely in the 40 year period of interest. The issue of glacier definition will be discussed as a possible cause of these drastic changes in the status of small, remnant glaciers. Recession trends will also be discussed with respect to glacier characteristics and regional distribution.  Barry, R. G., Progress in Physical Geography, 2006. 30(3): p. 285-306;  Dowdeswell, J. A., et al., Quaternary Research, 1997. 40: p. 1-14;  Ommanney, C. S. L., McGill Subarctic Research Paper, 1969. 40: p. 5-67.
Schaffer, Janin; Timmermann, Ralph; Kanzow, Torsten; Arndt, Jan Erik; Mayer, Christoph; Schauer, Ursula
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 transport towards the base of the 79°N-Glacier.
Gerbaux, M.; Genthon, C.; Dedieu, J.; Balestrieri, J.
Like most other glaciers in the Alps, the St Sorlin glacier (french Alps, 45.16°N, 6.16°E, 2900 m asl mean elevation and 3km2 of surface area) has been retreating fast in the last 20 years. To understand the meteorological factors responsible for this retreat, and to tentatively predict glaciers evolution in a changing (warming) climate, we use a distributed snow/ice mass and energy balance model derived from the CROCUS snow model (Météo-France). There is no direct meteorological observation on or near St Sorlin glacier yet, and hourly meteorology to force the snow/ice model is obtained from disaggregated meteorological analyses. The model is found to reproduce the St Sorlin mass balance of the last 20 years as obtained from field glaciological measurements and stereophotographic reconstructions. The model is also found to reproduce the interannual variations of the equilibrium line as determined from optical satellite imagery. Because of the albedo feedback involved, it is also important to verify that the summer snow/ice transition on the glacier is correctly simulated. Thus, an automated photographic system was set up facing St Sorlin glacier to monitor the evolution of the snow cover. The system was installed on the 13th of July 2004 and is still in operation at time of abstract writing. Digital photographies are taken every 4 hours, permitting so far at least one non-obstructed (rain, fog) picture per day. The first pictures in the series show an almost fully snow-covered glacier while the latest ones show bare ice up to the highest parts of the glacier. Snow is occasionally deposited during precipitation events but hardly last more than 3 days. Snow line position is deduced from pictures using a DEM with georeferenced points visible on pictures. It should then be compared with the modelled one. The automated photographic system provides not only snow cover to check snow/ice model results at seasonal time-scales, but also qualitative meteorological information (precipitation, cloud cover, fog) that may also help verify some aspects of the disaggregated meteorology in input of the model.
Falatkova, Kristyna; Sobr, Miroslav; Engel, Zbynek; Jansky, Bohumir
Recent development of glacier complex Adygine and resulting risks Falátková, K., Šobr, M., Engel, Z., Janský, B. Charles University in Prague, Faculty of Science, Prague, Czech republic Glacier complex Adygine (3,400-4,200 m asl) is situated on the northern flank of the Kyrgyz Range, Tien Shan, Kyrgyzstan. The valley downstream is part of National Park Ala Archa, which is popular with tourists, and is heading towards the country's capital - Bishkek. At the study site there is a glacier which is observed since 1960's. The glacier has been monitored by satellite imagery and in last 10 years by on-site geodetic measurement as well. Due to glacier shrinkage several glacial lakes of different genetic types (moraine-dammed, moraine- and rock-dammed, termokarst) have appeared at the site. Nowadays, the lakes are situated on three levels in front of the glacier's terminus and form a cascade, they are also hydrologically connected. The lakes were subjected to detailed bathymetric measurement and some parts of the dams were surveyed by geophysical methods. Especially the newest lakes in proximity of the terminus has been undergoing dynamic changes and may pose a threat in the near future. The risks arising together with changing climatic conditions and retreat of the glacier are associated with mainly three of the lakes. The largest one with area of 3.2 ha is dammed by a rock step overlaid by a moraine. Geophysical research of the dam revealed buried ice and seepage channels in its western part. It is the capacity of these subsurface channels, which are draining the lake throughout the year that represents a weak point in terms of dam stability. The second lake, a termokarst one, is a similar case but drained solely by subsurface channels. Very steep slopes of the lake basin are covered with loose material which could slide down and block the drainage channels. The lake would then fill all the basin (approx. 50,000 m3) very quickly as it is supplied with water from the large upper lake. The third lake is in contact with glacier terminus and has been enlarging substantially in last years. In case of outburst, this lake would drain to the mentioned termokarst lake. The valley beneath this complex was mapped by geodetic station and this data should serve as a base for flood modelling which is being prepared. Large amount of loose material (older part of moraine) is available on the valley floor and would be entrained by the flow. Therefore there is a possibility that the flood could be transformed into a debris flow.
Johnson N. Nkem; Diana H. Wall; Ross A. Virginia; John E. Barrett; Emma J. Broos; Dorota L. Porazinska; Byron J. Adams
Dispersal of soil organisms is crucial for their spatial distribution and adaptation to the prevailing conditions of the Antarctic\\u000a Dry Valleys. This study investigated the possibility of wind dispersal of soil invertebrates within the dry valleys. Soil\\u000a invertebrates were evaluated in (1) pockets of transported sediments to lake ice and glacier surfaces, (2) wind-transported\\u000a dust particles in collection pans (Bundt
Carlson, P.R.; Cowan, E.A.; Powell, R.D.; Cai, J.
A small Holocene fan is forming where Queen Inlet, a hanging valley, enters West Arm fjord, Glacier Bay, Alaska. Queen fan formed in the last 80 years following retreat of the Little Ice Age glacier that filled Glacier Bay about 200 yr BP. It was built mainly by a turbidite system originating from Carroll Glacier delta, as the delta formed in the early 1900s at the head of Queen Inlet. The Late Holocene Queen fan is comparable to large Pleistocene fans that formed in the Gulf of Alaska and differs from trough-mouth fans formed by cooler climate glacier systems.
Rupper, S.; Maurer, J. M.; Schaefer, J. M.; Tsering, K.; Rinzin, T.; Dorji, C.; Johnson, E. S.; Cook, E. R.
The rapid retreat of many glaciers in the monsoonal Himalaya is of potential societal concern. However, the retreat pattern in the region has been very heterogeneous, likely due in part to the inherent heterogeneity of climate and glaciers within the region. Assessing the impacts of glacier change on water resources, hydroelectric power, and hazard potential requires a detailed understanding of this potentially complex spatial pattern of glacier sensitivity to climate change. Here we quantify glacier surface-mass balance and meltwater flux across the entire glacierized region of the Bhutanese watershed using a full surface-energy and -mass balance model validated with field data. We then test the sensitivity of the glaciers to climatic change and compare the results to a thirty-year record of glacier volume changes. Bhutan is chosen because it (1) sits in the bulls-eye of the monsoon, (2) has >600 glaciers that exhibit the extreme glacier heterogeneity typical of the Himalayas, and (3) faces many of the economic and hazard challenges associated with glacier changes in the Himalaya. Therefore, the methods and results from this study should be broadly applicable to other regions of the monsoonal Himalaya. Our modeling results show a complex spatial pattern of glacier sensitivity to changes in climate across the Bhutanese Himalaya. However, our results also show that <15% of the glaciers in Bhutan account for >90% of the total meltwater flux, and that these glaciers are uniformly the glaciers most sensitive to changes in temperature (and less sensitive to other climate variables). We compare these results to a thirty-year record of glacier volume changes over the same region. In particular, we extract DEMs and orthorectified imagery from 1976 historical spy satellite images and 2006 ASTER images. DEM differencing shows that the glaciers that have changed most over the past thirty years also have the highest modeled temperature sensitivity. These results suggest that, despite the complex glacier heterogeneity in the region, the regional meltwater resources are controlled by a very small percentage of the glaciers, and that these glaciers are particularly vulnerable to changes in temperature.
A multidecadal review of glacier fluctuations and case-studies of glacier processes and environments in central East Greenland will be used to demonstrate Mechanisms that Amplify, Attenuate and Deviate glacier response to climate forcings (MAAD). The different spatial and temporal scales at which MAAD affect mass balance and ice flow may complicate interpretation and longterm extrapolation of glacier response to climate change. A framework of MAAD characterisation and best-practice for interpreting climate signals while taking into account MAAD will be proposed. Glaciers in the Watkins Bjerge, Geikie Plateau and Stauning Alps regions of central East Greenland (68°-72°N) contain about 50000 km2 of glacierized area peripheral to the Greenland Ice Sheet. Within the region, large north-south and coast-inland climatic gradients, as well as complicated topography and glacier dynamics, result in discrepant glacier behaviour. Average retreat rates have doubled from about 2 to 4 km2 a-1 between the late 20th and early 21st centuries. However, glaciers terminating along the Atlantic coast display two times the retreat, thinning, and acceleration rates compared to glaciers terminating in inland fjords or on land. Despite similar climatic forcing variable glacier behaviour is apparent: individual glacier length change ranges from +57 m a-1 to -428 m a-1, though most retreat -20 to -100 m a-1. Interacting dynamic, mass balance and glacio-morphological mechanisms can amplify, attenuate or deviate glacier response (MAAD) to climate change, thus complicating the climatological interpretation of glacier length, area, and thickness changes. East Greenland MAAD include a range of common positive and negative feedback mechanisms in surface mass balance and terminus and subglacial boundary conditions affecting ice flow, but also mechanisms that have longterm or delayed effects. Certain MAAD may affect glacier change interpretation on multiple timescales: e.g. surging glaciers do not only pose problems for the direct interpretation of climate change from length and volume changes due to their dynamically-driven advance and retreat regimes, but also for the reconstruction of LIA extents from trimlines and moraines, and the reconstruction of surface mass balance due to crevasses, potholes or debris-cover. This presentation will address a range of MAAD, including thermal regime transitions; ocean influences on tidewater-terminating glaciers; glacier fragmentation and tributary-trunk interaction; glacier surging and tidewater behaviour; seasonal variations; glacier hypsometry and morphology; terrain and substrate; melt-albedo and melt-ice flow feedbacks; and ice marginal lakes.
Wind erosion refers to the detachment, transport and deposition of sediment by wind. It is a dynamic, physical process where loose, dry, bare soils are transported by strong winds. Wind erosion is a soil degrading process that affects over 500 million ha of land worldwide and creates between 500 an...
Penna, Daniele; Engel, Michael; Mao, Luca; Dell'Agnese, Andrea; Bertoldi, Giacomo; Comiti, Francesco
The release of water as snowmelt and ice melt in high elevation catchments has significant social and economic impacts for population living in mountain areas. This is even more critical under the current conditions of glacier retreat as a consequence of global warming. Therefore, it is important to understand the role of ice and snow meltwater on runoff dynamics and groundwater recharge in glacierized environments. This task can be effectively accomplished by integrating isotopic and other tracers that are widely recognized as useful tools for the identification of the main water sources contributing to streamflow. In this work, we collected water samples from different sources in the Saldur catchment (Eastern Italian Alps). The catchment (area: 62 km², elevation range: 1600-3700 m a.s.l.) hosts a small glacier (2.8 km²) in its upper portion. Samples of rainfall, snow, snowmelt, glacier melt, stream water (main stream and tributaries) and spring water have been manually collected between April-October 2011 and April-November 2012 approximately on a monthly basis. Furthermore, 24-hour samplings with hourly collection frequency were performed at two cross sections during five melt-runoff events. The composition in stable water isotopes was determined by laser spectroscopy and mass spectrometry. Electrical conductivity (EC) and water temperature were measured in the field. Additionally, deuterium excess (DE) was computed for all samples based on the relationship between deuterium and 18-oxygen. The isotopic composition of rainfall and snow shows marked altitudinal and seasonal variations. A strong positive correlation is also evident in the relationship between DE of spring waters and elevation. Rainfall and snow samples fall perfectly on the Global Meteoric Water Line, revealing a predominant Atlantic origin of air masses producing precipitation in the study area. EC and water temperature linearly increase with the distance from the glacier snout, suggesting a decreasing influence of snow and glacier melt water (cold and little conductive) and an increasing contribution of non-glacierized areas moving downstream. Stream water shows a strong daily variability in isotopic composition and EC correlated well with discharge and air temperature, suggesting the relevant contribution of meltwater on runoff. Moreover, a seasonal trend is also observable in stream water and groundwater, with the most isotopically enriched and highest EC values found at low flow conditions (no melting periods), in early spring and late autumn. In agreement with these observations, end-member mixing analysis shows that summer precipitation plays a minor role on runoff temporal variability compared to glacier melt and snowmelt. Two- and three-component hydrograph separation for the summer melt-runoff events confirms the significant contribution of melting-event water (up to 73% for the upper station) and the importance of snowmelt and glacier melt (up to 37% and 28%, respectively) as water sources for streamflow at the daily scale in the study catchment. These results underline the critical role played by meltwater stored in glaciers and snow on water availability in mountain regions. Moreover, this works reveals the usefulness of a multi-tracer approach for the analysis of the main contributors to streamflow in glacierized catchments. Keywords: water stable isotopes, deuterium excess, electrical conductivity, snowmelt, glacier melt.
Classification of Debris-Covered Glaciers and Rock Glaciers in the Andes of Central Chile - An Approach Integrating Field Measurements, High-Resolution Satellite Imagery, and Coring Data to Estimate Water Resources
Janke, J. R.; Bellisario, A. C.; Ferrando, F. A.
In the Dry Andes of Chile (17 to 35° S), debris-covered glaciers and rock glaciers are differentiated from "true" glaciers based on the percentage of surface debris cover, thickness of surface debris, and ice content. These landforms are more numerous than glaciers in the Central Andes; however, there are often omitted from inventories. Glaciers, debris covered glaciers, and rock glaciers are being removed by mining, while agricultural expansion and population growth have placed an additional demand on water resources. As a result, it is important to identify and locate these features to implement sustainable solutions. The objective of this study is to develop a classification system to identify debris-covered glaciers and rock glaciers based on satellite imagery interpretation. The classification system is linked to field observations and measurements of ice content. Debris covered glaciers have three subclasses: surface coverage of semi (Class 1) and fully covered (Class 2) glaciers differentiates the first two forms, whereas debris thickness is critical for Class 3 when glaciers become buried with more than 3 m of surface debris. The amount of ice decreases from more than 85%, to 65-85%, to 45-65% for semi, fully, and buried debris-covered glaciers, respectively. Rock glaciers are characterized by three stages. Class 4 rock glaciers have pronounced transverse ridges and furrows that arch across the surface, which indicate flow produce via ice. Class 5 rock glaciers have ridges and furrows that appear linear in the direction of flow, and Class 6 rock glaciers have subdued surface topography that has been denudated as the rock glacier ceases movement. Ice content decreases from 25-45% ice, to 10-25% ice, to less than 10% ice from Class 4 to 6, respectively. The classification scheme can be used to identify and map debris covered glaciers and rock glaciers to create an inventory to better estimate available water resources at the basin-wide scale.
Bernard, É.; Friedt, J. M.; Saintenoy, A.; Tolle, F.; Griselin, M.; Marlin, C.
Glacier limits are usually mapped according to a spatial discrimination based on color of remote sensing images or aerial photography. What appears like ice (white or light colored areas) at the end of the ablation period (end of summer) corresponds to the glacier, while what appears as rock (dark areas) is identified as the slope. This kind of visual discretization seems to be insufficient in the case of small arctic glaciers.
Prokop, Alexander; Tolle, Florian; Bernard, Eric; Friedt, Jean-Michel; Griselin, Madeleine
For 3 consecutive years, terrestrial laser scanning surveys have been conducted in the glacier basin of Austre Lovénbreen (Svalbard, 79°N). Each year, high density point clouds were acquired on the glacier surface and on the surrounding slopes. Two yearly scanning sessions were required in order to spatialize and quantify snow cover. The first session was done late April at the expected annual snow maximum. The second session was done in August near the end of the melting season. On the glacier itself, laser scans were produced on the glacier snout, in the area close to the equilibrium line, and in the upper reaches of the glacier. Manual snow drilling measurements and glacier mass balance data were subsequently used to validate snow cover results. In the steep slopes surrounding the glacier, scans were acquired on slopes at various altitudes and orientations in order to get a representative view of different snow cover settings. Particular attention was granted to snowdrift and avalanche processes, and their consequences on remaining packed snow stored in perennial snow accumulation at the bottom of slopes. A good knowledge of the dynamics of the snow cover is of particular interest in a glacier undergoing a clear retreat. Snow is protecting the ice from melting for part of the season, and snow is also providing what will constitute future glacier ice in the upper reaches of the basin. Snow on slopes is also of importance as avalanches reaching on the glacier can contribute to the overall mass balance. Snow cover, by keeping the slopes permafrost from thawing early in the season, or by providing liquid water affecting it later in the season, is also playing a key role in the glacier basin morphology and its interactions with the glacier body.
Yang, X.; Zhang, T.; Qin, D.; Kang, S.; Qin, X.; Liu, H.
Ground-based measurements are essential for understanding alpine glacier dynamics, especially in remote regions where in-situ measurements are extremely limited. The meteorological and radiative fluxes were measured over the accumulation area on the East Rongbuk Glacier, Mt. Qomolangma (the Mt. Everest) at elevation of 6,560 m a.s.l. Measurements were conducted using an automatic weather station (AWS) from May 1 through July 22, 2005 (spring-summer period) and from October 2 of 2007 through January 20 of 2008 (autumn-winter period). Surface meteorological and radiative characteristics were strongly controlled by two major synoptic circulation regimes: the southwesterly Indian monsoon regime in summer and the westerlies in winter. At the AWS site on the East Rongbuk Glacier, north or northwest winds prevail with higher wind speed (up to 35 ms-1 in January) in winter and south or southeast winds predominate after the onset of the southwesterly Indian monsoon with relatively low wind speed in summer. Intensity of incoming shortwave radiation is extremely high due to its high elevation and high reflective surrounding surface. The striking feature is that the observed 10-minute mean incoming shortwave radiative fluxes around local noon were frequently higher than the solar constant at the top of the atmosphere from May through July, 2005. The observed higher-than-solar-constant values are mainly due to the impact of local convective broken clouds and high surface reflectivity over the surrounding terrains. We estimated that horizontal component of received diffusive solar radiation from surrounding terrains ranged from 140 to 310 Wm-2, accounting for about 10 to 25% of the observed incoming shortwave radiation under clear sky conditions. This value could be even higher under overcast cloudy days. The mean surface albedo ranged from 0.72 during summer- spring period and 0.69 during the autumn-winter period. The atmospheric incoming longwave radiation was strongly controlled by cloud conditions and atmospheric moisture content. Overall impact of clouds on net radiation balance is negative in Mt. Qomolangma region. The daily mean net all-wave radiation was positive during the entire spring-summer period and mostly positive during the autumn-winter period except a few overcast cloudy days. On monthly basis, net all-wave radiation was always positive.
Slayback, D. A.; Tucker, C. J.
We report on the climatic trends associated with glacier recession in the tropical Andes from the mid-1980s to the mid-2000s. These glaciers comprise 99% of the world's tropical glaciers and occur in Bolivia, Peru, Ecuador, Colombia, and Venezuela. We previously reported on our comprehensive analysis of Landsat imagery of these glaciers, which indicated an overall recession of approximately 30% in glacierized area between c1987 and c2006, or a drop from ~2500 km2 to ~1800 km2 in total glacier area. In the current work, we have examined trends in temperature, cloud cover, and precipitation and compared these trends with those in glacier recession. For temperature and cloud cover, we use the MERRA reanalysis datasets (Modern Era Retrospective-Analysis for Research and Applications) produced by the NASA Goddard's GMAO (Global Modeling and Assimilation Office), which are based on satellite observations. For precipitation, we use the GPCP (Glocal Precipitation Climatology Project) datasets, which are based on both ground and satellite observations. We find that over the glacierized zones, the only significant trends are those in temperature, which show increases of up to 0.5 degree C per decade over some glacierized areas. Trends in cloud cover and precipitation are not generally significant. We discuss these trends in relation to glacier recession trends for each of the major glacierized areas of the tropical Andes.
Hood, Eran; Battin, Tom J.; Fellman, Jason; O'Neel, Shad R.; Spencer, Robert G. M.
Polar ice sheets and mountain glaciers, which cover roughly 11% of the Earth's land surface, store organic carbon from local and distant sources and then release it to downstream environments. Climate-driven changes to glacier runoff are expected to be larger than climate impacts on other components of the hydrological cycle, and may represent an important flux of organic carbon. A compilation of published data on dissolved organic carbon from glaciers across five continents reveals that mountain and polar glaciers represent a quantitatively important store of organic carbon. The Antarctic Ice Sheet is the repository of most of the roughly 6 petagrams (Pg) of organic carbon stored in glacier ice, but the annual release of glacier organic carbon is dominated by mountain glaciers in the case of dissolved organic carbon and the Greenland Ice Sheet in the case of particulate organic carbon. Climate change contributes to these fluxes: approximately 13% of the annual flux of glacier dissolved organic carbon is a result of glacier mass loss. These losses are expected to accelerate, leading to a cumulative loss of roughly 15 teragrams (Tg) of glacial dissolved organic carbon by 2050 due to climate change — equivalent to about half of the annual flux of dissolved organic carbon from the Amazon River. Thus, glaciers constitute a key link between terrestrial and aquatic carbon fluxes, and will be of increasing importance in land-to-ocean fluxes of organic carbon in glacierized regions.
Braithwaite, R. J.
Translated into modern terminology, Kurowski suggested in 1891 that the equilibrium line altitude (ELA) of a glacier is equal to the mean altitude of the glacier when the whole glacier is in balance between accumulation and ablation. Kurowski's method has been widely misunderstood, partly due to inappropriate use of statistical terminology by later workers, and has been little tested except by Braithwaite and Müller in a 1980 paper (for 32 glaciers). I now compare Kurowski's mean altitude with balanced-budget ELA calculated for 103 modern glaciers with measured surface mass balance data. Kurowski's mean altitude is significantly higher (at 95% level) than balanced-budget ELA for 19 outlet and 42 valley glaciers, but not significantly higher for 34 mountain glaciers. The error in Kurowski mean altitude as a predictor of balanced-budget ELA might be due to generally lower balance gradients in accumulation area compared with ablation areas for many glaciers, as suggested by several workers, but some glaciers have higher gradients, presumably due to precipitation increase with altitude. The relatively close agreement between balanced-budget ELA and mean altitude for mountain glaciers (mean error -8 m with standard deviation 59 m) may reflect smaller altitude ranges for these glaciers such that there is less room for effects of different balance gradients to manifest themselves.
Naz, B. S.; Frans, C. D.; Clarke, G. K. C.; Burns, P.; Lettenmaier, D. P.
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. 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.
Sturm, M.; Hall, D.K.; Benson, C.S.; Field, W.O.
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-1 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.
Wouters, B; Martin-Español, A; Helm, V; Flament, T; van Wessem, J M; Ligtenberg, S R M; van den Broeke, M R; Bamber, J L
Growing evidence has demonstrated the importance of ice shelf buttressing on the inland grounded ice, especially if it is resting on bedrock below sea level. Much of the Southern Antarctic Peninsula satisfies this condition and also possesses a bed slope that deepens inland. Such ice sheet geometry is potentially unstable. We use satellite altimetry and gravity observations to show that a major portion of the region has, since 2009, destabilized. Ice mass loss of the marine-terminating glaciers has rapidly accelerated from close to balance in the 2000s to a sustained rate of -56 ± 8 gigatons per year, constituting a major fraction of Antarctica's contribution to rising sea level. The widespread, simultaneous nature of the acceleration, in the absence of a persistent atmospheric forcing, points to an oceanic driving mechanism. PMID:25999505
Zou, Han; Zhou, Libo; Ma, Shupo; Li, Peng; Wang, Wei; Li, Aiguo; Jia, Jingjing; Gao, Dengyi
To better understand the local wind systems in the Himalayas, wind and related atmospheric parameters were observed in the Rongbuk Valley on the northern slope of Mt. Everest, during the HEST2006 campaign, from May 29 to June 29, 2006. Data analysis and a simple numerical simulation show that the dominating down-valley flow in this valley is mainly formed by the thermally driven winds, ``valley wind'', ``mountain wind'' and ``glacier wind''. The vertical air motion is composed of a descending flow from the morning to midnight and an ascending flow for the rest of the day, with important modification from the vertical component of the above down-valley flow and a compensation flow of the ``slope wind''. The analysis also shows that the local wind system is well confined in the Rongbuk Valley due to topographic shielding effects.
Glaciers in Alaska have been increasingly losing mass over the last several decades. This trend is especially apparent in South-Central Alaska where many glaciers are undergoing rapid changes and contributing substantially to rising sea levels (Arendt et al., 2002). It is important to understand the rates at which these glaciers are losing mass as well as the important climatic drivers to better prepare for what the future holds in this region and the rest of the world. This work compares glacier mass balance data modeled through the Precipitation-Temperature Area Altitude (PTAA) mass balance model for the Wolverine Glacier in the Kenai Peninsula in South-Central Alaska to observed data from the USGS “benchmark” glacier program in order to help validate the model. The mass balance data are also correlated with climate data in order to understand the main climatic drivers of the glacier mass balance in this region.
Helmstetter, Agnès.; Nicolas, Barbara; Comon, Pierre; Gay, Michel
While basal icequakes associated with glacier motion have been detected under Antarctica for several decades, there remains very little evidence of stick-slip motion for Alpine glaciers. Here we analyzed 2357 basal icequakes that were recorded at Glacier d'Argentière (Mont-Blanc Massif) between February and November of 2012 and that are likely to be associated with basal sliding. These events have been classified into 18 multiplets, based on their waveforms. The strong similarity of the waveforms within each multiplet suggests an isolated repeating source. Despite this similarity, the peak amplitude within each multiplet varies gradually in time, by up to a factor of 18. The distribution of these events in time is relatively complex. For long time scales, we observe progressive variations in the amplitudes of events within each multiplet. For intermediate time scales (hours), the events occur regularly in time, with typical return times of several minutes up to several hours. For short time scales (from 0.01 to 100 s), the largest multiplet shows clustering in time, with a power law distribution of the interevent times. The location of these events and their focal mechanisms are not well constrained, because most of these events were detected by a single seismometer. Nevertheless, the locations can be estimated with an accuracy of a few tens of meters using a polarization analysis. The estimated average depth of the basal events is 179 m, which is in good agreement with the estimated glacier thickness. The relative changes in distance between the source and the sensor can be measured accurately by correlating separately the P wave and S wave parts of the seismograms of each event with the template waveforms, which are obtained by averaging the signals within each multiplet. We observed small variations in the times between the P wave and the S wave of up to 0.6 ms over 50 days. These variations cannot be explained by displacement of the sensor with respect to the glacier but might be due to small changes in the seismic wave velocities with time. Finally, we found using numerical simulations that the observed signals are better explained by a horizontal shear fault with slip parallel to the glacier flow than by a tensile fault. These results suggest that the basal events are associated with stick-slip motion of the glacier over rough bedrock. The rupture length and the slip are difficult to estimate. Nonetheless, the rupture length is likely to be of the order of meters, and the total seismic slip accumulated over one day might be as large as the glacier motion during the most active bursts.
Rieg, Lorenzo; Galos, Stephan; Klug, Christoph; Sailer, Rudolf
The mountain ranges in the area of the Autonomous Province of Bozen - South-Tyrol (Italy) contain numerous glaciers of various sizes and in different elevations and expositions. During the annual melt period, the runoff of these glaciers feeds the Etsch-river, which is the main water source for the extensive fruit production in the Vinschgau, an inner alpine dry valley with very low precipitation. Nevertheless, relatively little is still known about the current state of the glaciers in this area, except from the glacier inventories for 1983, 1997 and 2005/2006 and few glaciers which are subject to mass-balance studies. The study area encompasses the glaciers within the main part of the Ortler-Cevedale group (Sulden and Martell valleys), which is the most heavily glaciated region in South-Tyrol, the glaciers of the upper Ulten valley and the glaciers of the Schnals valley at the alpine main ridge. For this study, two sets of airborne laser scanning (ALS) data are used to calculate the recent changes in glacier area and volume. ALS data from 2005 is available from the Autonomous Province of Bozen, while another data acquisition campaign was conducted in context of the project MALS (Multitemporal Airborne Laserscanning South-Tyrol) in autumn 2011. The extents of all glaciers in the study areas have been delineated for both dates, based on digital terrain models (DTM), hillshades and intensity information. Those results are used to calculate changes in the glaciated areas. The geodetic mass balance for al studied glaciers is calculated as well. Therefore, changes in glacier volume between 2005 and 2011 and their altitudinal distribution are calculated from the differences of the ALS-based DTM. The results of the mass-balance calculations for the single glaciers are interpreted with respect to their spatial distribution, taking topographic parameters such as altitudinal distribution of glacier area, slope into account.
Horgan, Huw; Anderson, Brian
The potential for glacier, ice cap, and ice sheet discharge acceleration has been highlighted as a major source of uncertainty in sea level rise predictions and is particularly uncertain in the case of debris-covered glaciers. Changes affecting basal sliding can cause the flow of glaciers and ice sheets to change at a variety of timescales. Debris-cover influences basal sliding by buffering the glacier against short-term melt events and changing the overall glacier profile. Here we use a long-term GPS deployment to investigate the flow of Tasman Glacier, a large debris covered glacier in the Southern Alps of New Zealand. Tasman Glacier demonstrates no detectable diurnal velocity variability, significant seasonal variability, and remarkable acceleration in response to rainfall events. During times of heavy rainfall, Tasman Glacier accelerates to speeds of up to 36 times its normal speed (from 0.12 m d-1 to 4.45 m d-1). Peak speeds are maintained for periods of less than 12 hours before rapidly decaying to slightly above background levels. Recording many speed up events allows the relationship between rain-rate and glacier speed to be determined enabling us to estimate the effect rainfall events have on annual glacier speed and inter-annual variability. Comparing speed up events with bed separation estimates indicates that the initial acceleration is likely a direct result of the growth of basal cavities. Basal sliding theory implies that the sensitivity of glacier speed to water input is increased by glacier down wasting, which lowers the effective pressure at the bed, indicating that rain induced speed-up events are likely to become increasingly common on Tasman Glacier.
Putnam, A. E.; Schaefer, J. M.; Denton, G. H.; Hall, B. L.; Lowell, T. V.; Porter, C. T.; Barrell, D. J.; Andersen, B. G.; Kaplan, M. R.; Koffman, T.; Lennon, J.; Rowan, A. V.; Finkel, R. C.; Rood, D.; Schwartz, R.; Vandergoes, M.; Plummer, M. A.; Brocklehurst, S. H.; Kelley, S. E.; Ladig, K. L.
The termination of the last ice age featured a major reconfiguration of Earth's climate and cryosphere, yet the underlying causes of these massive changes continue to be debated. Documenting the spatial and temporal variations of atmospheric temperature during deglaciation can help discriminate among potential drivers. Here, we present 10Be surface-exposure chronologies and glaciological reconstructions of ice recession following the Last Glacial Maximum in the New Zealand Southern Alps and Patagonian Andes. Our field sites straddle opposite sides of the South Pacific and record climate changes near Southern Ocean fronts. Most of the deglacial warming in the Southern Alps and southern Andes occurred during the early part of the Heinrich Stadial 1 (HS1) of the North Atlantic region. We attribute southern mid-latitude warming and glacier recession during HS1 to a southward shift of the Subtropical and Subantarctic Fronts. Because these oceanic fronts are associated with the position of the westerly wind belt, our findings support the concept that a southward shift of Earth's wind belts accompanied the early parts of HS1 cooling in the North Atlantic, leading to major warming and deglaciation in southern middle latitudes.
Paul, Frank; Bolch, Tobias; Mölg, Nico; Rastner, Philipp
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) over the analysed time period, length changes of surging glaciers can exceed several kilometres with a continuum of advance rates and surge durations (from 2 to >10 years). Their highly variable extents have thus to be considered when glacier-specific volume changes and flow velocities are calculated. In the presentation we will show our revised assignment of surging glaciers, their changing extents through time along with an analysis of their variable advance rates, and a spatio-temporal overview of glacier changes over the past 50 years.
Raup, Bruce H.
complex geospatial objects. MapServer is a flexible and easy tool for serving data on the WebThe GLIMS Glacier Database: a spatio-temporal database implemented using Open Source tools Bruce small budgets). Capable, and fast! Runs on Linux, where we can take advantage of our stock of Linux
Cogley, J. Graham; Ecclestone, M. A.; Andersen, D. T.
Direct, in situ measurements of glacier mass balance are expensive. Remote sensing would be an attractive alternative if remotely observable quantities could be interpreted in terms of mass gain or loss. A system developed recently for the analysis of Radarsat browse images is used here to explore temporal and environmental controls of melting on glaciers on Axel Heiberg Island, Nunavut, Canada. The browse images have an effective spatial resolution of 2 km, are georeferenced to single-pixel accuracy, and number about 200 over the two study years, 1998 and 1999. Surface melting in the accumulation zone is readily recognized by the contrast between bright frozen firn, which exhibits a microwave signal dominated by volume scattering from ice lenses and pipes, and dark wet firn, the signal from which is muted by either absorption or near-specular reflection at the surface. In the ablation zone, radar images, apart from showing the brief spring period of snowmelt, contain little information about the intensity or even the fact of melting. However, in the accumulation zone there is a definite dependence of brightness on temperature: at temperatures above freezing, the hotter it is the darker is the appearance of the glacier. This is most naturally (and encouragingly) interpreted as a relation between brightness and melting rate. Analysis of same-day image pairs shows that, as expected, the terrain slope and the aspect influence the radar brightness strongly and must therefore be allowed for in future modelling of the hydrology of ablation on glaciers.
Ágústsson, Hálfdán; Ólafsson, Haraldur; Pálsson, Finnur
The large Icelandic glaciers have a significant effect on the mesoscale atmpospheric flow in Iceland. Their impact on the spatial distribution of precipitation is clearly indicated in the annual maxima observed near the ice caps at the south coast of Iceland. This maxima is associated with the high and broad orographic features and with the frequent passage of atmospheric lows and fronts. To quantify the effect of the glaciers on the flow, two sets of high-resolution atmospheric simulations have been performed. The control simulation uses the current land height and glacial cover while in the sensitivity run the glaciers have been removed and the bottom topography of the glaciers used instead of the glacial surface as land height. The simulations are done at 8 and 2 km horizontal resolution and are forced with the Interim re-analysis of the ECMWF for two consecutive years 2004-2006. The key results for Vatnajökull ice cap in Southeast-Iceland indicate up to 25% decrease in annual precipitation on large parts of the ice cap and an overall decrease close to 15% when the glacial cover is removed. There is furthermore greater spillover of precipitation in regions near the west and north edge of the ice cap but little changes further in the lee of the ice cap. The results of this study are of relevance for planning of hydropower availability and harnessing in a warming climate.
Fagre, D. B.; McKeon, L. A.
Repeat photography has proven to be an effective means to communicate the pace and scope of climate change impacts to Glacier National Park, Montana for broad audiences. The repeat photographs of glaciers vividly document their rate of disappearance and have been used in books, magazines, TV documentaries, on websites, and in several art museum exhibits. In our ongoing efforts to enhance information transfer about climate change to audiences, we have capitalized on an emerging technology by partnering with GigaPan Systems to test the effectiveness of a Gigapan camera system. A Gigapan camera system is a robotically controlled DSLR camera mount that is programmed to take multiple high-resolution digital photographs of objects or entire landscapes in sequence and with overlap between adjoining photographs. The multiple (e.g. 800) photographs are digitally stitched with post production software into one large merged image and served online as a gigapixel panorama. Key objects or parts of the image can be zoomed into at great detail and highlighted as “snapshots”. The snapshot images retain high image resolution and can then be annotated and information such as datasets, maps, or additional images can be linked to that part of the image. GigaPan images can be georeferenced in Google Earth and embedded in websites. We have used this visually compelling technology to photograph alpine glaciers in Glacier Park and create interactive experiences for online users. Results are available at: http://gigapan.org/ Gigapan system with robotically controlled camera
Variations in the quantity and quality of meltwaters draining Peyto Glacier, Alberta, are assessed to examine to what extent meltwater characteristics might be indicative of any distinctive source and routing of water through a glacierised drainage basin. Continuous monitoring of solute concentrations of the principle melt-stream, Peyto Creek, was undertaken for significant periods in 1982, 1984 and 1987, coupled with
Maya Bhatia; Martin Sharp; Julia Foght
Bacterial communities reside in basal ice, sediment, and meltwater in the supra-, sub-, and proglacial environments of John Evans Glacier, Nunavut, Canada. We examined whether the subglacial bacterial com- munity shares common members with the pro- and supraglacial communities, and by inference, whether it could be derived from communities in either of these environments (e.g., by ice overriding proglacial sediments
This, the first of two repeat photographs, documents significant changes that have occurred during the nine years between photographs A and B. Although Muir Glacier has retreated more than 3 kilometers and thinned more than 100 meters, exposing Muir Inlet, it remains connected with tributary Riggs G...
on the Siple Coast ice streams and Amundsen Sea embayment of West Antarctica. As a result, we have an incomplete understanding of many key details of the current configura- tion and dynamics of these glaciers, and are ill-equipped to model their response...
Williamson, Craig E.
Melting Alpine Glaciers Enrich High-Elevation Lakes with Reactive Nitrogen J A S M I N E E . S A R biomass, and fossil diatom species richness in two sets of high-elevation lakes: those fed by snowpack. Although nitrogen (N) limitation is common in alpine lakes, algal biomass was lower in highly N
HAROLD D. PICTON
Grizzly bears (Ursus arctos horribilis) have been observed in 5 of the 7 mountain areas that link the Northern Continental Divide (Glacier Park) and Yellowstone ecosystem grizzly bear populations in Montana. Thus these 2 populations, recognized by the Grizzly Bear Recovery Plan (U.S. Dep. Int. 1981) are possibly linked by a filter bridge. Portions of this bridge are not included
Schmitt, C. G.; All, J.; Schwarz, J. P.; Arnott, W. P.; Warthon, J.; Andrade, M.; Celestian, A. J.; Hoffmann, D.; Cole, R. J.; Lapham, E.; Horodyskyj, U. N.; Froyd, K. D.; Liao, J.
Glaciers in the tropical Andes have been losing mass rapidly in recent decades. In addition to the documented increase in temperature, increases in light absorbing particulates deposited on glaciers could be contributing to the observed glacier loss. Here we present results of measurements of light absorbing particles from glaciers in Peru and Bolivia. Samples have been collected by American Climber Science Program volunteers and scientists at altitudes up to 6770 meters. Collected snow samples were melted and filtered in the field. A new inexpensive technique, the Light Absorption Heating Method (LAHM) has been developed for analysis of light absorbing particles collected on filters. Results from LAHM analysis are calibrated using filters with known amounts of fullerene soot, a common industrial surrogate for black carbon (BC). For snow samples collected at the same field location LAHM analysis and measurements from the Single Particle Soot Photometer (SP2) instrument are well correlated (r2 = 0.92). Co-located SP2 and LAHM filter analysis suggest that BC could be the dominant absorbing component of the light absorbing particles in some areas.
Ruth S. Hindshaw; Ben C. Reynolds; Jan G. Wiederhold; Ruben Kretzschmar; Bernard Bourdon
The biogeochemical cycling and isotopic fractionation of calcium during the initial stages of weathering were investigated in an alpine soil chronosequence (Damma glacier, Switzerland). This site has a homogeneous silicate lithology and minimal biological impacts due to sparse vegetation cover. Calcium isotopic compositions, obtained by TIMS using a 43Ca–46Ca double spike, were measured in the main Ca pools. During this
E. P. Baltsavias; S. Mason; H. Li; A. Stefanidis; M. Sinning
The paper compares the Leica\\/Helava DPW 770 and VirtuoZo digital photogrammetric sys- tems and in particular their performance in automatic generation of Digital Surface Models (DSM) in mountainous areas with glaciers. The aim of this project was twofold. Firstly, we wanted to test whether automated photogram- metric processes, especially for DSM generation, could be applied in mountainous regions that include
Salcher, Bernhard; Reinhard, Starnberger; Götz, Joachim
The Northern Alpine Foreland was repeatedly covered by massive piedmont glaciers during Quaternary peak glacial periods. Remnants of the Salzach foreland glacier (Austria/Germany) represent the easternmost of a series of piedmont glaciers entering the Foreland by major Alpine valleys reaching far into the Alpine Molasse. The area of the former Salzach foreland glacier (SFG) marks a unique place as remnants of at least 4 glacial maxima meet an abundant geodatabase including information on the digital topography and the internal built up of glacial deposits derived from outcrops and several hundreds of drillings. During the LGM, it covered an area of more than 1000 km² and was even more extensive during older peak glacial periods. The lack of absolute ages as well as systemic investigation of the internal built up did so far impede the reconstruction on its dynamics. Here we aim to bring more light into the erosional and depositional history of a typical north Alpine piedmont glacier, the SFG, by analyzing drill log data, field outcrops, topography and the depositional ages of sediments. We focus on the proximal (axial) and distal parts of the SFG lobe. Some of the major unresolved questions regarding the Quaternary evolution of the major Alpine foreland glaciers are: Is the glacial erosion of Miocene bedrock the consequence of one glacial cycle or does it rather reflect successive erosional events during each glacial period? What is the spatial variability and potential depth of erosion? What is the structure and internal built up these deposits? The intent of this study is not to answer these questions in detail but to deliver important constraints: Our results indicate that more than 300- 400 m of bedrock were eroded during an early peak glacial period (such as antepenultimate glacial period or even earlier). Erosion was rather uniform across the lobe with larger values only occurring in the center (axis) of the glacier. Accumulation of more than 100 m of deposits occurred later, potentially during the antepenultimate and penultimate glacial maximum (MIS 6). Deposits suggest a characteristic stratigraphy of glaciofluvial sediments and basal tills, with the lithofacies of fluvial sediments varying from the proximal to distal lobe parts. The general impact of the LGM (MIS2) seems to be minor.
Wijngaard, René R.; Helfricht, Kay; Schneeberger, Klaus; Huttenlau, Matthias; Schneider, Katrin; Bierkens, Marc F. P.
Future climate change is expected to alter the runoff characteristics of glacierized catchments, which is expected to have consequences for the water availability in these catchments. For this reason it is important to understand and to assess the impact of climate change on the hydrology of glacierized catchments. In this study, the hydrological response of glacierized catchments to future climate change is investigated in the Ötztal Alps, Austria. For this purpose, two conceptual hydrological models, HBV and HQsim, were applied for the simulation of future daily discharge in three (nested) catchments with different degrees of glaciation. The models were forced with a combination of downscaled climate scenarios and glacier scenarios. For downscaled climate scenarios, projections of daily temperature and precipitation for the period 1985-2100 were used that were derived from three combinations of general circulation models (GCMs) and regional climate models (RCMs). These projections were subsequently used in a delta change approach. Daily anomalies of temperature and precipitation were calculated for (i) 2010-2039, (ii) 2040-2069, and (iii) 2070-2099, on the basis of the original meteorological data series of 1983-2012. A one-way coupling scheme with an empirical glacier model, able to simulate future glacial evolution as a result of climate change, was used to force the models with glacier scenarios. Subsequently, the outcomes of the hydrological models are used to analyse changes in the seasonality of high runoff conditions, absolute and relative changes, the seasonality of annual flood peaks, and low flow characteristics. Under the future conditions the outcomes show initially runoff increases for all catchments without changes in the runoff regimes. On the long-term, summer runoff is expected to decrease and winter/spring runoff is expected to increase in all catchments. These runoff changes are accompanied with regime shifts from glacial/glacio-nival runoff regimes to runoff regimes with a higher nival component. Changing runoff conditions might also lead to changes in the seasonality of annual flood peaks with an earlier appearance of flood peaks through the year, and an increasing abundance of low flow conditions during summer months. The results of this study help to have a better understanding of the future impact of climate change on the water cycle of glacierized catchments.
Sterzai, P.; Mancini, F.; Corazzato, C.; D Agata, C.; Diolaiuti, G.
Aiming at reconstructing superficial velocity and volumetric variations of alpine glaciers, SAR interferometry (InSAR) technique is, for the first time in Italy, applied jointly with the glaciological classic field methods. This methodology with its quantitative results provides, together with other space geodesy techniques like GPS, some fundamental elements for the estimation of the climate forcing and the evaluation of the future glacier trend. InSAR is usually applied to antarctic glaciers and to other wide extralpine glaciers, detectable by the SAR orbits; in the Italian Alps, the limited surface area of the glaciers and the deformation of radar images due to strong relief effect, reduce the applicability of this tecnique. The chosen glacier is suitable for this kind of study both for its large size and for the many field data collected and available for the interferometric results validation. Forni Glacier is the largest valley glacier in the Italian Alps and represents a good example of long term monitoring of a valley glacier in the Central Alps. It is a north facing valley glacier formed by 3 ice streams, located in Italian Lombardy Alps (46 23 50 N, 10 35 00 E). In 2002 its area was approximately 13 km2, extending from 2500 to 3684 m a.s.l., with a maximum width of approximately 7500 m and a maximum length of about 5000 m. Available data include mass-balance measurements on the glacier tongue (from the hydrological year 1992-1993 up to now), frontal variations data from 1925 up to now, topographical profiling by means of GPS techniques and profiles of the glacier bed by geoelectrical surveys (VES) (Guglielmin et alii, 1995) and by seismic surveys (Merlanti et alii, 2001). In order to apply radar interferometry on this glacier eight ERS SAR RAW images have been purchased, in addition to the Digital Elevation Model from IGM (Geographic Military Institute), and repeat pass interferometry used. Combining the different passes, differential interferograms are computed and velocity map obtained. The validation of interferometric data was possible comparing them with the field glaciological data obtained by GPS velocity surveys in the years 1992-1993 (Vittuari and Smiraglia, unpublished) and 1996-1997, which resulted of about 20m/y. The InSAR results give further contributions in the estimation of the velocity field of Forni Glacier for a deeper understanding of the different flow lines of the glacier. Problems related to relief effect, loss of coherence, geometry of satellite imagery and geocoding, are also discussed.
LeWinter, A. L.; Finnegan, D. C.; Hamilton, G. S.; Stearns, L. A.; Gadomski, P. J.
Greenland's fast-flowing tidewater outlet glaciers play a critical role in modulating the ice sheet's contribution to sea level rise. Increasing evidence points to the importance of ocean forcing at the marine margins as a control on outlet glacier behavior, but a process-based understanding of glacier-ocean interactions remains elusive in part because our current capabilities for observing and quantifying system behavior at the appropriate spatial and temporal scales are limited. A recent international workshop on Greenland's marine terminating glaciers (US CLIVAR, Beverly, MA, June 2013) recommended the establishment of a comprehensive monitoring network covering Greenland's largest outlet glacier-fjord systems to collect long-term time series of critical in situ glaciological, oceanographic and atmospheric parameters needed to understand evolving relationships between different climate forcings and glacier flow. Given the remote locations and harsh environments of Greenland's glacial fjords, the development of robust autonomous instrumentation is a key step in making the observing networks a reality. This presentation discusses the design and development of a fully-autonomous ground-based Light Detection and Ranging (LiDAR) system for monitoring outlet glacier behavior. Initial deployment of the system is planned for spring 2015 at Helheim Glacier in southeast Greenland. The instrument will acquire multi-dimensional point-cloud measurements of the mélange, terminus, and lower-reaches of the glacier. The heart of the system is a long-range, 1064 nm wavelength Terrestrial Laser Scanner (TLS) that we have previously used in campaign-style surveys at Helheim Glacier and at Hubbard Glacier in Alaska. We draw on this experience to design and fabricate the power and enclosure components of the new system, and use previously acquired data from the instrument, collected August 2013 and July 2014 at Helheim, to optimize our data collection strategy and design the data processing and telemetry subsystems to ensure year-round data collection.
Carturan, L.; Filippi, R.; Seppi, R.; Gabrielli, P.; Notarnicola, C.; Bertoldi, L.; Paul, F.; Rastner, P.; Cazorzi, F.; Dinale, R.; Dalla Fontana, G.
A widespread loss of glacier area and volume has been observed in the European Alps since the 1980s. In addition to differences among various regions of the Alps, different responses to climate change characterize neighboring glaciers within the same region. In this study we describe the glacier changes in the Ortles-Cevedale group, the largest glacierized area in the Italian Alps. We analyze the spatial variability, the drivers, and the main factors controlling the current loss of ice in this region, by comparing mean elevation changes derived from two digital terrain models (DTMs), along with glacier extents and snow-covered areas derived from Landsat images acquired in 1987 and 2009, to various topographic factors. Glacier outlines were obtained using the band ratio method with manual corrections. Snow was classified from a near-infrared image after topographic correction. The total glacierized area shrank by 23.4 ± 3% in this period, with no significant changes in the mean altitude of the glaciers. In 2009 the snowline was 240 m higher than in the 1960s and 1970s. From the snow-covered area at the end of summer 2009, which fairly represents the extent and local variability of the accumulation areas in the 2000s, we estimate that approximately 50% of the remaining glacier surfaces have to melt away to re-establish balanced mass budgets with present climatic conditions. The average geodetic mass budget rate, calculated for 112 ice bodies by differencing two DTMs, ranged from -0.18 ± 0.04 to -1.43 ± 0.09 m w.e. a-1, averaging -0.69 ± 0.12 m w.e. a-1. The correlation analysis of mass budgets vs. topographic variables emphasized the important role of hypsometry in controlling the area and volume loss of larger glaciers, whereas a higher variability characterizes smaller glaciers, which is likely due to the higher importance of local topo-climatic conditions.
Molnia, B. F.; Karpilo, R. D.; Pranger, H. S.
Historical photographs, many dating from the late-19th century are being used to document landscape and glacier change in the Glacier Bay area. More than 350 pre-1980 photographs that show the Glacier Bay landscape and glacier termini positions have been acquired by the authors. Beginning in 2003, approximately 150 of the sites from which historical photographs had been made were revisited. At each site, elevation and latitude and longitude were recorded using WAAS-enabled GPS. Compass bearings to photographic targets were also determined. Finally, using the historical photographs as a composition guide, new photographs were exposed using digital imaging and film cameras. In the laboratory, 21st century images and photographs were compared with corresponding historical photographs to determine, and to better understand rates, timing, and mechanics of Glacier Bay landscape evolution, as well as to clarify the response of specific glaciers to changing climate and environment. The comparisons clearly document rapid vegetative succession throughout the bay; continued retreat of larger glaciers in the East Arm of the bay; a complex pattern of readvance and retreat of the larger glaciers in the West Arm of the bay, coupled with short-term fluctuations of its smaller glaciers; transitions from tidewater termini to stagnant, debris-covered termini; fiord sedimentation and erosion; development of outwash and talus features; and many other dramatic changes. As might be expected, 100-year-plus photo comparisons show significant changes throughout the Glacier Bay landscape, especially at the southern ends of East and West Arms. Surprisingly, recent changes, occurring since the late-1970s were equally dramatic, especially documenting the rapid thinning and retreat of glaciers in upper Muir Inlet.
Armstrong, W. H., Jr.; Anderson, R. S.; Allen, J.; Rajaram, H.; Anderson, L. S.
The coupling of glacial hydrology and sliding is a source of uncertainty for both ice flow modeling and prediction of future sea level rise. As basal sliding is required for a glacier to erode its bed, the spatial pattern of glacier sliding is also important for understanding alpine landscape evolution. We use multi-temporal WorldView satellite imagery (0.5 m pixel) to monitor the seasonal progression of glacier velocity across the terminal ~50 km2of Kennicott Glacier, Alaska. We employ the free image correlation software COSI-Corr to construct multiple velocity maps, using 2013 imagery with repeat times from 15 to 38 days. These short intervals between images allow us to analyze variations in glacier velocity over weekly to monthly timescales associated with hydrologically-induced basal sliding. By assuming that spring (March-April) glacier velocity results solely from viscous deformation, we produce spatially distributed maps of glacier sliding speed by differencing summer and spring ice surface speeds. For a given time, a large portion of our study reach slides with roughly uniform speed, despite significant variation in deformation speed. This suggests that glacier flow models in which basal sliding is taken simply to scale as ice surface velocity are unfounded. The upglacier end of our study reach slides at speeds that vary through the summer, whereas the terminal reach slides at a steady speed. The proportion of glacier motion due to sliding increases dramatically moving downglacier, making basal sliding especially important in the terminal region. Many formulations express glacier sliding as a function of effective pressure (ice pressure minus water pressure). If such formulations are correct, effective pressure varies little over large areas or is averaged over lengthscales equivalent to ~10 glacier thicknesses. Also, effective pressure is steady in the terminal region through the summer. We explore existing sliding laws to find which best describes the observed spatiotemporal pattern of sliding.
Brown, A.; Howat, I.; Behar, A.; Box, J. E.; Tulaczyk, S.
Observations of short-term variations in the flow speed of marine-terminating outlet glaciers are essential for understanding the dynamics of these systems in relation to changes in surface melting and calving. Due to their inaccessiblity and highly crevassed and unstable surfaces, there is little existing ice motion data for polar outlet glaciers at high-temporal and spatial resolution over multi-week timescales. Here we present the results, successes, and planned improvements of a proof- of-concept study at Store Glacier,West Greenland in 2008 where we deployed both dual frequency and inexpensive L1 single frequency receivers. The dual-frequency system, was deployed roughly 15 km from the ice front near a large supraglacial lake and recorded at 1 s epochs. Three single frequency receivers, recording at 10 s epochs, were installed within 5 km of the ice front and transmitted their data to a base station on the side of the glacier. Dual frequency data was post processed using GAMIT's kinematic software package TRACK. However, multiple attempts at post processing the L1 phase data were unsuccessful due to multipath cycleslip intensity, massive clock drift, and data corruption, so that only the pseudorange data could be utilized. By combining the high-rate motion data with concurrent meteorology,time-lapse photography and seismographic data, we assess how variations in motion correspond with changes in meltwater production, calving and sea ice conditions at the front. Based on this initial deployment, we propose future improvements including increased data collection robustness, use of chokering antennae for multipath mitigation, broadcast GPS clock correction, and dual frequency disposable rover solutions for drastically improved positional analysis at the glacier front.
Bassis, J. N.; O'Leary, M.
Observations indicate that the dynamics of ocean terminating glaciers is tightly coupled to the presence of pro-glacial mélange, a freely floating mixture of icebergs, sea ice and snow that clogs fjords. Mechanical considerations, in contrast, suggest that mélange should lack the structural integrity necessary to disrupt the calving cycle. In this study, we address this discrepancy using an idealized model in which mélange is represented as discrete blocks of ice that interact through elastic and frictional forces. Intact glacier ice is simulated as a matrix of boulders of ice that are glued together with breakable bonds. This modeling framework realizes the discrete granular nature of mélange and enables the mélange to mechanically interact with a (continuous) glacier. Using characteristic thickness and geometry of a Helheim-like glacier we find that if the fjord is mélange free, through penetrating fractures develop near the terminus leading to the detachment of sub-ice-thickness scale bergs that rotate and capsize. However, when mélange is present, inelastic collisions between the detaching berg and mélange inhibit movement of the berg away from the calving front. This effect is magnified when protrusions from the bed (e.g., a very thick sill) or walls cause iceberg "traffic jams". These traffic jams limit the rate at which icebergs can be exported away from the terminus and create compressive chains that provide a compressive backstress to the terminus. Although the compressive stress is small compared to the tensile deviatoric stress within the ice, it is sufficient to prevent or at least delay further calving events. This suggests that tidewater glacier retreat may be limited by the export of icebergs away from the terminus and this, like most traffic jams, is strongly controlled by the presence of obstacles that force traffic to converge or take inefficient detours.
Schütte, Ursel M E; Abdo, Zaid; Foster, James; Ravel, Jacques; Bunge, John; Solheim, Bjørn; Forney, Larry J
Over the past 100 years, Arctic temperatures have increased at almost twice the global average rate. One consequence is the acceleration of glacier retreat, exposing new habitats that are colonized by microorganisms whose diversity and function are unknown. Here, we characterized bacterial diversity along two approximately parallel chronosequences in an Arctic glacier forefield that span six time points following glacier retreat. We assessed changes in phylotype richness, evenness and turnover rate through the analysis of 16S rRNA gene sequences recovered from 52 samples taken from surface layers along the chronosequences. An average of 4500 sequences was obtained from each sample by 454 pyrosequencing. Using parametric methods, it was estimated that bacterial phylotype richness was high, and that it increased significantly from an average of 4000 (at a threshold of 97% sequence similarity) at locations exposed for 5 years to an average of 7050 phylotypes per 0.5 g of soil at sites that had been exposed for 150 years. Phylotype evenness also increased over time, with an evenness of 0.74 for 150 years since glacier retreat reflecting large proportions of rare phylotypes. The bacterial species turnover rate was especially high between sites exposed for 5 and 19 years. The level of bacterial diversity present in this High Arctic glacier foreland was comparable with that found in temperate and tropical soils, raising the question whether global patterns of bacterial species diversity parallel that of plants and animals, which have been found to form a latitudinal gradient and be lower in polar regions compared with the tropics. PMID:20331770
Clitherow, Leonie R.; Carrivick, Jonathan L.; Brown, Lee E.
Glacier retreat is occurring across the world, and associated river ecosystems are expected to respond more rapidly than those in flowing waters in other regions. The river environment directly downstream of a glacier snout is characterised by extreme low water temperature and unstable channel sediments but these habitats may become rarer with widespread glacier retreat. In these extreme environments food web dynamics have been little studied, yet they could offer opportunities to test food web theories using highly resolved food webs owing to their low taxonomic richness. This study examined the interactions of macroinvertebrate and diatom taxa in the Ödenwinkelkees river, Austrian central Alps between 2006 and 2011. The webs were characterised by low taxon richness (13–22), highly connected individuals (directed connectance up to 0.19) and short mean food chain length (2.00–2.36). The dominant macroinvertebrates were members of the Chironomidae genus Diamesa and had an omnivorous diet rich in detritus and diatoms as well as other Chironomidae. Simuliidae (typically detritivorous filterers) had a diet rich in diatoms but also showed evidence of predation on Chironomidae larvae. Food webs showed strong species-averaged and individual size structuring but mass-abundance scaling coefficients were larger than those predicted by metabolic theory, perhaps due to a combination of spatial averaging effects of patchily distributed consumers and resources, and/or consumers deriving unquantified resources from microorganisms attached to the large amounts of ingested rock fragments. Comparison of food web structural metrics with those from 62 published river webs suggest these glacier-fed river food web properties were extreme but in line with general food web scaling predictions, a finding which could prove useful to forecast the effects of anticipated future glacier retreat on the structure of aquatic food webs. PMID:23613751
Tayal, S.; Hasnain, S. I.
Glaciers play a crucial role in maintaining ecosystem stability as they act as buffers and regulate the runoff water supply from high mountains to the plains during both dry and wet spells. Retreat of Hindu Kush-Himalaya-Tibetan glaciers is one of the major environmental problems facing the south Asian and south-east Asian region. The Himalayan mountain range spans 2500 km east to west and includes diverse cultures of five countries (Afghanistan, Pakistan, India, Tibet (China), Nepal, Bhutan) and a range of weather patterns, which has been strongly affected by regional climate change. The glaciers of Indian Himalayan ranges covers an area of 19000 km2 contains over 9500 glaciers and feed major perennial river systems like Indus, Ganges, Brahmaputra, and sustain the livelihood of over 0.5 billion south Asians. Glaciers are melting fast but their response time varies from westerly nourished Kashmir Himalaya glaciers to south-west monsoon nourished Sikkim Himalaya glaciers based on regional climatic variations. Changes in mass balance of a glacier are considered as the most direct representative of the impacts of meteorological parameters on the glacier dynamic responses. A comparative study of mass balance, based on field measurements techniques is being conducted on two benchmark glaciers in the Indian Himalaya. The glaciers currently being monitored are Kolahoi glacier (340 07 - 340 12 N: 750 16 - 750 23E), Kashmir Himalaya and E.Rathong glacier (270 33 - 480 36 N: 880 06 - 880 08 E), Sikkim Himalaya. One year mass balance results (2008-2009) for both the benchmark glaciers are now available and are being presented. Mass balance for Kolahoi glacier located in sub-tropical to temperate setting and nourished by westerly system show range from -2.0 m.w.e. to -3.5 m.w.e. per annum. Whereas, the E. Rathong glacier located in tropical climatic settings and nourished by SW monsoon system show range from -2.0 m.w.e. to -5.0 m.w.e. per annum. The (2009/2010) mass balance data is being processed and will be presented during the AGU workshop on Third Pole glaciers. The results show that the global climate change impacts are widespread over Indian Himalaya however, local geographic and climatic settings play a dominating influence on the melting behaviour of these glaciers, and there exists a sharp gradient in rate of melting from western to eastern Himalaya.
Azzoni, Roberto; Franzetti, Andrea; Ambrosini, Roberto; D'Agata, Carlo; Senese, Antonella; Minora, Umberto; Tagliaferri, Ilario; Diolaiuti, Guglielmina
Supraglacial debris has an important role in the glacier energy budget and has strong influence on the glacial ecosystem. Sediment derives generally from rock inputs from nesting rockwalls and are abundant and continuous at the surface of debris-covered glaciers (i.e. DCGs; glaciers where the ablation area is mainly covered by rock debris) and sparse and fine on debris-free glaciers (DFGs). Recently, evidence for significant tongue darkening on retreating debris-free glaciers has been drawing increasing attention. Fine particles, the cryoconite, are locally abundant and may form cryoconite holes that are water-filled depressions on the surface of DFGs that form when a thin layer of cryoconite is heated by the sun and melts the underlying ice. There is increasing evidence that cryoconite holes also host highly diverse microbial communities and can significantly contribute to global carbon cycle. However, there is almost no study on microbial communities of the debris cover of DCGs and there is a lack of data from the temporal evolution of the microbial communities in the cryoconites. To fill these gaps in our knowledge we characterized the supraglacial debris of two Italian DCGs and we investigated the temporal evolution of microbial communities on cryoconite holes in DFG. We used the Illumina technology to analyse the V5 and V6 hypervariable regions of the bacterial 16S rRNA gene amplified from samples collected distances from the terminus of two DCGs (Miage and Belvedere Glaciers - Western Italian Alps). Heterotrophic taxa dominated bacterial communities, whose structure changed during downwards debris transport. Organic carbon of these recently exposed substrates therefore is probably provided more by allochthonous deposition of organic matter than by primary production by autotrophic organisms. We used ARISA fingerprinting and quantitative PCR to describe the structure and the evolution of the microbial communities and to estimate the number of the total bacteria and the copy of Rubisco genes found on cryoconite holes collected on a wide Italian DFG (Forni Glacier - Central Alps). The structure of the microbial communities in cryoconite holes seem to be determined mainly by a turnover process. This work was carried out under the umbrella of the SHARE Stelvio Project which has been funded by the Lombardy Region government and managed by FLA (Lombardy Foundation for the Enviroment) and EvK2-CNR Committee.
Stibal, Marek; Hasan, Fariha; Wadham, Jemma L; Sharp, Martin J; Anesio, Alexandre M
Microbial ecosystems beneath glaciers and ice sheets are thought to play an active role in regional and global carbon cycling. Subglacial sediments are assumed to be largely anoxic, and thus various pathways of organic carbon metabolism may occur here. We examine the abundance and diversity of prokaryotes in sediment beneath two glaciers (Lower Wright Glacier in Antarctica and Russell Glacier in Greenland) with different glaciation histories and thus with different organic carbon substrates. The total microbial abundance in the Lower Wright Glacier sediment, originating from young lacustrine sediment, was an order of magnitude higher (~8 × 10(6) cells per gram of wet sediment) than in Russell Glacier sediment (~9 × 10(5) cells g(-1)) that is of Holocene-aged soil origin. 4% of the microbes from the Russell Glacier sediment and 0.04-0.35% from Lower Wright Glacier were culturable at 10°C. The Lower Wright Glacier subglacial community was dominated by Proteobacteria, followed by Firmicutes. The Russell Glacier library was much less diverse and also dominated by Proteobacteria. Low numbers and diversity of both Euryarchaeota and Crenarchaeota were found in both sediments. The identified clones were related to bacteria with both aerobic and anaerobic metabolisms, indicating the presence of both oxic and anoxic conditions in the sediments. PMID:22241643
Steinlin, Christine; Bogdal, Christian; Scheringer, Martin; Pavlova, Pavlina A; Schwikowski, Margit; Schmid, Peter; Hungerbühler, Konrad
In previous work, Alpine glaciers have been identified as a secondary source of persistent organic pollutants (POPs). However, detailed understanding of the processes organic chemicals undergo in a glacial system was missing. Here, we present results from a chemical fate model describing deposition and incorporation of polychlorinated biphenyls (PCBs) into an Alpine glacier (Fiescherhorn, Switzerland) and an Arctic glacier (Lomonosovfonna, Norway). To understand PCB fate and dynamics, we investigate the interaction of deposition, sorption to ice and particles in the atmosphere and within the glacier, revolatilization, diffusion and degradation, and discuss the effects of these processes on the fate of individual PCB congeners. The model is able to reproduce measured absolute concentrations in the two glaciers for most PCB congeners. While the model generally predicts concentration profiles peaking in the 1970s, in the measurements, this behavior can only be seen for higher-chlorinated PCB congeners on Fiescherhorn glacier. We suspect seasonal melt processes are disturbing the concentration profiles of the lower-chlorinated PCB congeners. While a lower-chlorinated PCB congener is mainly deposited by dry deposition and almost completely revolatilized after deposition, a higher-chlorinated PCB congener is predominantly transferred to the glacier surface by wet deposition and then is incorporated into the glacier ice. The incorporated amounts of PCBs are higher on the Alpine glacier than on the Arctic glacier due to the higher precipitation rate and aerosol particle concentration on the former. Future studies should include the effects of seasonal melt processes, calculate the quantities of PCBs incorporated into the entire glacier surface, and estimate the quantity of chemicals released from glaciers to determine the importance of glaciers as a secondary source of organic chemicals to remote aquatic ecosystems. PMID:24999726
Dendrochronology and radiocarbon dating of in situ and detrital wood have been utilized to date Holocene glacier fluctuations in Garibaldi Provincial Park and at the Pemberton Icefield in the southern Coast Mountains of British Columbia. Fieldwork at over 30 glaciers has been carried out since 2002. The focus of this paper is on wood that has been radiocarbon dated between 4500 and 4000 years ago, which has been found at six glaciers. At four glaciers the wood was washing out from beneath present-day glacier snouts. At Helm Glacier in Garibaldi Park thirteen detrital branches and stumps were recovered, and at West Squamish Glacier at the Pemberton Icefield seven detrital branches, stems, and stumps were sampled. Some of these samples had diameters of up to 40 cm and were up to 250 cm long, and thus are much larger than any living trees near the present treeline. Tree-ring analysis shows that these glaciers advanced into and over mature forests that had grown near present-day glacier margins for at least 135 years (Helm) and 357 years (W Squamish). Evidence for permanent snow and ice patches forming, as well as glaciers advancing beyond present-day extents at this time is found in the central Coast Mountains, Yukon Territory, Arctic Canada, Norway, and the Swiss Alps. Glacier advances of similar age have been reconstructed not only in western Canada, but also in Europe, Asia, South America, New Zealand, and Antarctica indicating the global nature of this event. A peak in ice-rafted debris in the North Atlantic about 4200 years ago may have been the result of reduced solar output, and based on Earth's position in the obliquity cycle glaciers should have started to expand 4000 years ago. These 'glacier forests' thus could provide a probable start date for Neoglaciation.
Ye, Q.; Moholdt, G.; Yao, T.; Liu, S.; Zhang, Y.
As it is known that continental glacier melting dramatically in a warmer climate and its mass loss contribute to the sea level rise, however, there are lots of inland lakes that receives glacier melting contributions to some extent, it is still not known how much melting water from glaciers to lakes overall on a global and regional view. On the Tibetan Plateau, there are four inland basins in contrast to six external catchments at the marginal plateau. With the same reference system, co-registration and bias/offsets correction, DEMs and ICESat/GLAS data were used to calculate glacier surface elevation changes, which includes the historical DEM at 1:250,000 in 1970s, SRTM DEM and ICESat/GLAS over the whole Tibetan Plateau. According to the 1st glacier inventory database by each glacier in different basins, glacier surface elevation changes were calculated, and glacier mass changes were evaluated. It shows that, for external catchments, glacier mass change was totalled by -9.5 ± 3.6 Gt a-1 during 1970s-2000, it was more negative during 2003-2009 (-14.9 ± 6.9 Gt a-1). It shows more melting glacier water runs into the sea in recent decade. However, it was obviously less than some previous studies in HMA, e.g. Gardner et al., 2013, glacier contributed to sea level rise by 26±12 Gt a-1 .While for internal basins overall, glacier mass change was totalled by -7.6 ± 2.3 Gt a-1 during 1970s-2000, however, it was less negative during 2003-2009 (-3.05± 1.4 Gt a-1). It seems that precipitation has increased in inland Tibet and there might be less glacier melting mass runs into inland lakes in recent decade.
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Millar, C. I.; Westfall, R. D.
Rock glaciers and related periglacial rock-ice features (RIFs) are common landforms in high, dry mountain ranges, and widely distributed throughout canyons of the Sierra Nevada, California, USA (Millar & Westfall, in press). Due to insulating rock carapaces, active rock glaciers (ice-cored) have been documented to maintain ice longer, and thus contribute to more enduring hydrologic output, under past warming climates than typical ice glaciers. This function has been suggested for the coming century. We propose a broader hydrologic and ecologic role for RIFs as temperatures rise in the future. For the Sierra Nevada, we suggest that canyons with either active or relict RIFs (Holocene and Pleistocene) maintain water longer and distribute water more broadly than canyons that were scoured by ice glaciers and are defined by primary river and lake systems. RIFs provide persistent, distributed water for extensive wetland habitat, rare in these otherwise barren, high, and dry locations. We mapped and assessed the area of wetlands surrounding active and relict RIFs from the central eastern Sierra Nevada; from these we delineated wetland vegetation community types and recorded plant species found in RIF-supported wetlands. Mid-elevation RIFs, likely inactive or with transient ice, develop soil patches on their rock matrix. At the Barney Rock Glacier (Duck Pass, Mammoth Crest), we inventoried plant species on all soil patches, and measured cover for each species per patch and total plant cover for the rock glacier. RIF landforms also appear to support high-elevation mammals. We show that American beaver (Castor canadensis) is associated with canyons dominated by active or relict RIFs and propose that the articulating, persistent, and distributed nature of streams makes dam-building easier than other canyons. Beavers further contribute to maintaining water and creating wetland habitat in upper watersheds by engineering ponds and marshes, and contributing to riparian extent. We also mapped 125 discrete locations of American pika (Ochotona princeps) and found a strong association of pika presence with active and relict RIFs, in particular cirque rock glaciers, valley rock glaciers, and boulder streams. Using the PRISM climate model and a small network of temperature dataloggers from RIF habitats, we present a climate envelope for the pika habitats we surveyed. We propose that the large area of RIFs in the Sierra Nevada over a range of elevations could provide extensive habitat for pika in the warming future. RIFs in general are a group of landforms little studied in high mountains of western North America but of potential increasing importance to hydrologic and ecologic function as climate warms in the future. Millar, C.I. and R.D. Westfall. In press. Rock glaciers and periglacial rock-ice features in the Sierra Nevada; Classification, distribution, and climate relationships. Quaternary International.
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Bolch, Tobias; Kutuzov, Stanislav; Rohrbach, Nico; Fischer, Andrea; Osmonov, Azamat
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 glaciers' 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. Glaciers in Central and Inner Tien Shan are typically polythermal or even cold and surrounded by permafrost. Several glaciers 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 glacier"). Hence, glaciers 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 glacier-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 glacier complex is in general heterogeneous. Several dead ice bodies with different thicknesses and moraine-derived rock glaciers with different stages of activities could be identified. Few parts of these "rock glaciers" contain also massive ice but the largest parts are likely characterised by rock-ice layers of different thickness and ice contents. In one glacier 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 glacier ice. Our measurements revealed that up to 20% of the total ice of the entire glacier-rock glacier-moraine-complex could be stored in the moraine-rock glacier parts.
Brisbourne, A.; Stuart, G.; Kulessa, B.
A multi-disciplinary shallow geophysics experiment was carried out near a prominent break in surface slope of the Grubengletscher, Valais, Switzerland, during the summer melt season of 2007. High-resolution reflection and refraction seismics, differential GPS, passive seismology, seismoelectric sounding and GPR profiling were undertaken. Here we present the initial results of the passive seismic experiment. An array of 6 high-frequency SAQS data loggers with 4.5Hz 3-component geophones was deployed on the surface of the glacier, around the break-of-slope, near the terminus of the glacier. An inter-station distance of around 50m was used, comparable to the ice thickness, with one instrument deployed at the centre of a ring of 5. Data were recorded continuously at 3000sps with GPS timing. Due to the rapid ablation rate the array required daily maintenance involving the re-seating of recording equipment, batteries and solar panels, as well as redeployment of the geophones to maintain correct orientation. Geophones were buried in small pits with a flat base chipped out of the ice with an ice-axe. Holes were then drilled for the three spikes of the sensor casing to achieve maximum coupling. The sensors were then covered with ice and overlain by rocks to inhibit surface melt. With no snow cover at the surface, deployment of the geophones became the most critical aspect of the deployment. Spurious resonances were observed in the data as a result of significant tilt of the geophones. With surface-melt in the cm/day range this kind of deployment would not be possible without daily attention. Dozens of events per hour are observed on all stations at all times of day and night. These signals encompass surface events such as rockfalls, and also crevassing and basal events. To allow the characterisation and identification of signal waveforms, the timing of known events such as rockfalls, footfalls, sledgehammer blows and "felt" glacial events were recorded. Initial results indicate a range of event types from simple impulsive crevasse-like events to highly complex large-amplitude events associated with rock-falls. When combined with the other geophysical data, the extraction of basal events from the plethora of data will allow the subglacial mechanism sustaining the flow instability of the glacier to be isolated. The findings are significant because the flow velocity of the Grubengletscher can reach some 45 m / year, which is fast for an Alpine glacier; thus, the glacier is anticipated to serve as a small-scale analogue for fast-flowing outlet glaciers from larger ice caps or ice sheets.
Hamilton, Samantha J.; Brian Whalley, W.
Preliminary results from the lichenometric dating studies undertaken using the collective lichen "species" Rhizocarpon geographicum sensu lato are presented and applied to the establishment of a rock glacier developmental chronology for the Nautardálur rock glacier, Tröllaskagi, northern Iceland. Absolute dates are tentatively postulated based on the application of the largest lichen thalli diameters to a regional Trollaskagi R. geographicum s.l. growth rate of 40 mm/ 100 yr. Lichenometric ages on the Nautardálur rock glacier range over a continuum from approximately 200 yr BP to present. A time-frame suggestive of rock glacier development initiated during or immediately after the Little Ice Age, when a small come glacier was inundated with rock debris which formed an insulating "skin" over the ice and permitted its preservation until present. Lichenometric dating therefore provides an independent means of dating rock glacier deposits which agrees well with relative ages postulated by other palaeo-reconstructional methods.
Dyurgerov, Mark B.; Abdalati, Waleed Dr. (Technical Monitor)
I have completed an update of global glacier volume change. All data of glacier annual mass balances, surface area over the period 1945/46 till 2004, outside the Greenland and Antarctic ice sheets were included in this update. As the result global glacier volume change have been calculated, also in terms of glacier contribution to sea level change. These results were sent to Working Group 1 and 2 of IPCC-4 as the basis for modeling of sea level towards the end of 2100. In this study I have concentrated on studying glacier systems of different scales, from primary (e.g. Devon ice cap) to regional (e.g. Canadian Arctic), continental scale (e,g., entire Arctic), and global (e.g., change in glacier volume and contribution to sea level rise).
Sangewar, C. V.
Indian Himalayan glaciers beset in rugged terrain and at an higher altitudes thus restricting approach to glaciers for mapping, observations and validation of remote sensed data and paucity of freely available topographic maps has added up source of errors. The scientific documentation of Himalayan glaciers initiated as part of World glacier monitoring programme of then International des glacier Commission in 1905,wherein glaciers of Karakorum, Lahaul Himalaya, erstwhile United Province area and Sikkim Himalayas were mapped, established photographic stations and cairns(Rec.GSI 35) Aerial photographs of the glaciers were obtained during sixties as part of modern survey of Indian territory which translated on toposheets. The period of aerial photography was Oct-Dec i.e. onset of winter in the higher reaches of Himalaya thereby most of the glaciers terminus and proglacial area was snow-covered. With the advent of satellite remote sensed data in seventies the glaciers studies got impetus (Vohra et al.1981) Data generated over the years by different agencies based on varied sources-cartographic/toposheets, field based and remote sensing has lead to redesign the methodology for accuracy of data with minimal errors. The methodology adopted by Geological Survey of India was preparation of detailed maps of the frontal part of glacier, establishment of photographic stations and 'cairns 'followed by repetitive monitoring of these glaciers over a period of time. Later studies necessitated interpretation of aerial photographs to study geomorphology of glacier and its proglacial area as the area was snow-covered and redemarcate snout on translated toposheet. Similarly, the remote sensed data was interpreted due to individual pixel size variation (73 m to 0.5m, present day) over a period of time. Interpretation of aerial photographs(1960-62,1978) for glacier studies is restricted to GSI, therefore the interpretations based on Survey of India toposheet(1960-63) has an inherent error which is duly reflected in the estimation of glacier recession/mass balance especially as in the case of Shaune garang glacier(Mukherjee &Sangewar,1997),Panchi Nala I(Patiseo),II(Shukla et al.2010) Gangotri glacier(Sangewar,1997). Glacier inventory of Himalayan glacier, mainly based on field data(Sangewar&Shukla,2009) and on remote sensed data(SAC/ISRO,2011) shows a wide variations in the number of glaciers(Gl no.) as well as glacierised area(sq km) viz. Chenab basin-Gl no.1278(GSI)/1569(SAC), Glacierised area 3058.99(GSI)/4016.91(SAC),Beas basin-Gl no.277(GSI)/335(SAC),Gl area-599.06(GSI)/698.06(SAC),Ravi basin-Gl no.172(GSI)/253(SAC),Gl area-192.75(GSI)/319.16(SAC),Bhagirathi basin-Gl no.238(GSI)/172(SAC),Gl area-755.43(GSI)/992.67(SAC) etc. Considering, wide variations in studies based on field based techniques and remote sensing method an approach is recommended as part of "Report of the Study Group on Himalayan Glaciers-2011" wherein over a selected glacier(s) integrated studies for glacier recession and mass balance by field and remote sensing techniques proposed. Thus the 'evolved model' can be extrapolated to other glaciers in a basin and on regional scale.
Wu, Xiaoqing; Paden, John; Jezek, Ken; Rignot, Eric; Gim, Young
We produced the high resolution bedmaps of several glaciers in western Greenland from IceBridge Mission sounding radar data using tomographic sounding technique. The bedmaps cover 3 regions: Russell glaciers, Umanaq glaciers and Jakobshavn glaciers of western Greenland. The covered areas is about 20x40 km(sup 2) for Russell glaciers and 300x100 sq km, and 100x80 sq km for Jakobshavn glaciers. The ground resolution is 50 meters and the average ice thickness accuracy is 10 to 20 meters. There are some void areas within the swath of the tracks in the bedmaps where the ice thickness is not known. Tomographic observations of these void areas indicate that the surface and shallow sub-surface pockets, likely filled with water, are highly reflective and greatly weaken the radar signal and reduce the energy reaching and reflected from the ice sheet bottom.
Uetake, Jun; Tanaka, Sota; Hara, Kosuke; Tanabe, Yukiko; Samyn, Denis; Motoyama, Hideaki; Imura, Satoshi; Kohshima, Shiro
Tropical regions are not well represented in glacier biology, yet many tropical glaciers are under threat of disappearance due to climate change. Here we report a novel biogenic aggregation at the terminus of a glacier in the Rwenzori Mountains, Uganda. The material was formed by uniseriate protonemal moss gemmae and protonema. Molecular analysis of five genetic markers determined the taxon as Ceratodon purpureus, a cosmopolitan species that is widespread in tropical to polar region. Given optimal growing temperatures of isolate is 20–30°C, the cold glacier surface might seem unsuitable for this species. However, the cluster of protonema growth reached approximately 10°C in daytime, suggesting that diurnal increase in temperature may contribute to the moss’s ability to inhabit the glacier surface. The aggregation is also a habitat for microorganisms, and the disappearance of this glacier will lead to the loss of this unique ecosystem. PMID:25401789
A NASA radar instrument has been successfully used to measure some of the fastest moving and most inaccessible glaciers in the world -- in Chile's huge, remote Patagonia ice fields -- demonstrating a technique that could produce more accurate predictions of glacial response to climate change and corresponding sea level changes. This image, produced with interferometric measurements made by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) flown on the Space Shuttle last fall, has provided the first detailed measurements of the mass and motion of the San Rafael Glacier. Very few measurements have been made of the Patagonian ice fields, which are the world's largest mid-latitude ice masses and account for more than 60 percent of the Southern Hemisphere's glacial area outside of Antarctica. These features make the area essential for climatologists attempting to understand the response of glaciers on a global scale to changes in climate, but the region's inaccessibility and inhospitable climate have made it nearly impossible for scientists to study its glacial topography, meteorology and changes over time. Currently, topographic data exist for only a few glaciers while no data exist for the vast interior of the ice fields. Velocity has been measured on only five of the more than 100 glaciers, and the data consist of only a few single-point measurements. The interferometry performed by the SIR-C/X-SAR was used to generate both a digital elevation model of the glaciers and a map of their ice motion on a pixel-per-pixel basis at very high resolution for the first time. The data were acquired from nearly the same position in space on October 9, 10 and 11, 1994, at L-band frequency (24-cm wavelength), vertically transmitted and received polarization, as the Space Shuttle Endeavor flew over several Patagonian outlet glaciers of the San Rafael Laguna. The area shown in these two images is 50 kilometers by 30 kilometers (30 miles by 18 miles) in size and is centered at 46.6 degrees south latitude, 73.8 degrees west longitude. North is toward the upper right. The top image is a digital elevation model of the scene, where color and saturation represent terrain height (between 0 meters and 2,000 meters or up to 6,500 feet) and brightness represents radar backscatter. Low elevations are shown in blue and high elevations are shown in pink. The digital elevation map of the glacier surface has a horizontal resolution of 15 meters (50 feet) and a vertical resolution of 10 meters (30 feet). High-resolution maps like these acquired over several years would allow scientists to calculate directly long-term changes in the mass of the glacier. The bottom image is a map of ice motion parallel to the radar look direction only, which is from the top of the image. Purple indicates ice motion away from the radar at more than 6 centimeters per day; dark blue is ice motion toward or away at less than 6 cm per day; light blue is motion toward the radar of 6 cm to 20 cm (about 2 to 8 inches) per day; green is motion toward the radar of 20 cm to 45 cm (about 8 to 18 inches) per day; yellow is 45 cm to 85 cm (about 18 to 33 inches) per day; orange is 85 cm to 180 cm (about 33 to 71 inches) per day; red is greater than 180 cm (71 inches) per day. The velocity estimates are accurate to within 5 millimeters per day. The largest velocities are recorded on the San Rafael Glacier in agreement with previous work. Other outlet glaciers exhibit ice velocities of less than 1 meter per day. Several kilometers before its terminus, (left of center) the velocity of the San Rafael Glacier exceeds 10 meters (32 feet) per day, and ice motion cannot be estimated from the data. There, a revisit time interval of less than 12 hours would have been necessary to estimate ice motion from interferometry data. The results however demonstrate that the radar interferometry technique permits the monitoring of glacier characteristics unattainable by any other means. Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) are part of NASA's
Apaloo, J.; Brenning, A.; Gruber, S.
Rock glaciers are creeping bodies of ice-rich permafrost typical in cold high-mountain environments. In the arid and semi-arid Andes, and presumably other dry high-mountain areas, rock glaciers are considered more significant than glaciers as a water resource. The active layer of rock glaciers, and other seasonally frozen ground, in more temperate high-mountain climates may also represent an important contribution to summer baseflow in lowland rivers. The multi-decadal evolution of rock glacier permafrost and its relationship to climate is largely unknown and presents a massive challenge to assess in-situ due to limited spatial and temporal observations, the resource-intensity of geophysical observation, and lack of meteorological observation in most rock glaciers areas. As a step in addressing these knowledge gaps, this work simulates a rock glacier based on the Murtel-Corvatsch rock glacier in the Upper Engadin, Switzerland - the most intensively studied rock glacier in the world. Three decades of high-quality hourly climate data are used to generate 50 year time-series of synthetic meteorological observations with the Advanced WEather GENerator (AWE-GEN) under the observed climate and 8 additional climate change scenarios. One-dimensional simulations of rock glaciers are conducted with the combined hydrological and energy balance model GEOtop, which is forced by the synthetic meteorological data. The experimental approach consists of three parts: 1) establishing a realistic rock glacier model under the observed climate, 2) subjecting the rock glacier to meteorological forcing from climate change scenarios, and 3) testing the sensitivity of the model to input parameters. For the mountain cryosphere community and many lowland populations around the world, this work represents an important outcome in developing the understanding and methodologies pertaining to the role of seasonal ice and permafrost in the hydrological cycle of high mountain watersheds.
Z. Zuo; J. Oerlemans
. ?The contribution of glacier melt, including the Greenland ice-sheet, to sea-level change since AD 1865 is estimated on the\\u000a basis of modelled sensitivity of glacier mass balance to climate change and historical temperature data. Calculations are\\u000a done in a regionally differentiated manner to overcome the inhomogeneity of the global distribution of glaciers. A distinction\\u000a is made between changes in summer
Larsen, C. F.; Bartholomaus, T. C.; O'Neel, S.; West, M. E.
We observe ice motion, calving and seismicity simultaneously and with high-resolution on an advancing tidewater glacier in Icy Bay, Alaska. Icy Bay’s tidewater glaciers dominate regional glacier-generated seismicity in Alaska. Yahtse emanates from the St. Elias Range near the Bering-Bagley-Seward-Malaspina Icefield system, the most extensive glacier cover outside the polar regions. Rapid rates of change and fast flow (>16 m/d near the terminus) at Yahtse Glacier provide a direct analog to the disintegrating outlet systems in Greenland. Our field experiment co-locates GPS and seismometers on the surface of the glacier, with a greater network of bedrock seismometers surrounding the glacier. Time-lapse photogrammetry, fjord wave height sensors, and optical survey methods monitor iceberg calving and ice velocity near the terminus. This suite of geophysical instrumentation enables us to characterize glacier motion and geometry changes while concurrently listening for seismic energy release. We are performing a close examination of calving as a seismic source, and the associated mechanisms of energy transfer to seismic waves. Detailed observations of ice motion (GPS and optical surveying), glacier geometry and iceberg calving (direct observations and timelapse photogrammetry) have been made in concert with a passive seismic network. Combined, the observations form the basis of a rigorous analysis exploring the relationship between glacier-generated seismic events and motion, glacier-fiord interactions, calving and hydraulics. Our work is designed to demonstrate the applicability and utility of seismology to study the impact of climate forcing on calving glaciers.
Anthony A. Arendt; Keith A. Echelmeyer; William D. Harrison; Craig S. Lingle; Virginia B. Valentine
We have used airborne laser altimetry to estimate volume changes of 67 glaciers in Alaska from the mid-1950s to the mid-1990s. The average rate of thickness change of these glaciers was -0.52 m\\/year. Extrapolation to all glaciers in Alaska yields an estimated total annual volume change of -52 +\\/- 15 km3\\/year (water equivalent), equivalent to a rise in sea level
Rastner, P.; Bolch, T.; Mölg, N.; Machguth, H.; Le Bris, R.; Paul, F.
Glacier inventories provide essential baseline information for the determination of water resources, glacier-specific changes in area and volume, climate change impacts as well as past, potential and future contribution of glaciers to sea-level rise. Although Greenland is heavily glacierised and thus highly relevant for all of the above points, a complete inventory of its glaciers was not available so far. Here we present the results and details of a new and complete inventory that has been compiled from more than 70 Landsat scenes (mostly acquired between 1999 and 2002) using semi-automated glacier mapping techniques. A digital elevation model (DEM) was used to derive drainage divides from watershed analysis and topographic attributes for each glacier entity. To serve the needs of different user communities, we assigned to each glacier one of three connectivity levels with the ice sheet (CL0, CL1, CL2; i.e. no, weak, and strong connection) to clearly, but still flexibly, distinguish the local glaciers and ice caps (GIC) from the ice sheet and its outlet glaciers. In total, we mapped ~ 20 300 glaciers larger than 0.05 km2 (of which ~ 900 are marine terminating), covering an area of 130 076 ± 4032 km2, or 89 720 ± 2781 km2 without the CL2 GIC. The latter value is about 50% higher than the mean value of more recent previous estimates. Glaciers smaller than 0.5 km2 contribute only 1.5% to the total area but more than 50% (11 000) to the total number. In contrast, the 25 largest GIC (> 500 km2) contribute 28% to the total area, but only 0.1% to the total number. The mean elevation of the GIC is 1700 m in the eastern sector and around 1000 m otherwise. The median elevation increases with distance from the coast, but has only a weak dependence on mean glacier aspect.
Katie L. Grant; Chris R. Stokes; Ian S. Evans
We present a comprehensive new inventory of surge-type glaciers on the Novaya Zemlya archipelago, using high-resolution (up to 4 m) satellite imagery from 1976\\/77 (Hexagon), 1989 (Landsat TM), 2001 (Landsat ETM+) and 2006 (ASTER). A total of 692 glaciers and their forelands were observed for glaciological and geomorphological criteria indicative of glacier surging (e.g. looped moraines, heavy surface crevassing, surface
A. T. Grove
Fluctuations in Holocene climate inferred from glaciers in mountain regions as described in Jean Grove [Grove, J.M., 2004. Little Ice Ages Ancient and Modern, 2nd edition, 2 vols. Routledge, London and New York.] are updated with selected publications that further explore the climate–glacier link. The significance of glacier fluctuations and their potential climatic forcing factors suggests that natural changes in solar
ASTER images are being used in an ambitious international project to map the extent of the worlds glaciers and the rate at which they are changing. High-resolution ASTER images make it possible to distinguish and track small features on glacier surfaces. Images presented by Rick Wessels from Arizona State University showing details of snow and ice of glaciers are contributing to the Global Land Ice Measurements from Space (GLIMS) project, a global consortium led by the U.S. Geological Survey.
ASTER images are being used in an ambitious international project to map the extent of the worlds glaciers and the rate at which they are changing. High-resolution ASTER images make it possible to distinguish and track small features on glacier surfaces. Images presented by Rick Wessels from Arizona State University showing details of snow and ice of glaciers are contributing to the Global Land Ice Measurements from Space (GLIMS) project, a global consortium led by the U.S. Geological Survey.
Harney, Jodi N.; Cochrane, Guy R.; Etherington, Lisa L.; Dartnell, Pete; Golden, Nadine E.; Chezar, Hank
In April 2004, more than 40 hours of georeferenced submarine digital video was collected in water depths of 15-370 m in Glacier Bay to (1) ground-truth existing geophysical data (bathymetry and acoustic reflectance), (2) examine and record geologic characteristics of the sea floor, and (3) investigate the relation between substrate types and benthic communities, and (4) construct predictive maps of seafloor geomorphology and habitat distribution. Common substrates observed include rock, boulders, cobbles, rippled sand, bioturbated mud, and extensive beds of living horse mussels and scallops. Four principal sea-floor geomorphic types are distinguished by using video observations. Their distribution in lower and central Glacier Bay is predicted using a supervised, hierarchical decision-tree statistical classification of geophysical data.
Haeberli, W.; Zemp, M.
Internationally coordinated observation of long-term glacier fluctuations as a key indication of global climate changes has a long tradition, starting already in 1894. With the development of the Global Climate Observing System in support of the United Nations Framework Convention on Climate Change, glaciers and ice caps became an Essential Climate Variable within the Global Terrestrial Observing System. A corresponding Global Terrestrial Network for Glaciers (GTN-G) was indeed established as a pilot project to this program. The basic principles followed by GTN-G and similar networks are to be relevant, feasible, comprehensive and understandable to a wider scientific community and the public. Following recommendations by the International Council for Sciences, a contribution should be made to free and unrestricted international sharing of high-quality, long-term and standardized data and information products. A tiered strategy was adopted in order to bridge the gap between detailed process studies at selected field sites with global coverage through satellite remote sensing. Efforts were also made to ensure continuity of long-term measurement series by combining traditional approaches with modern, future-oriented technologies. Today, the GTN-G is jointly run by three operational bodies in glacier monitoring, which are the World Glacier Monitoring Service, the US National Snow and Ice Data Center, and the Global Land Ice Measurements from Space initiative. With an online service, GTN-G provides fast access to regularly updated information on glacier fluctuation and inventory data. Currently, this includes global information from 100,000 glaciers mainly based on aerial photographs and outlines from 95,000 glaciers mainly based on satellite images, length change series from 1,800 glaciers, mass balance series from 250 glaciers, information on special events (e.g., hazards, surges, calving instabilities) from 130 glaciers, as well as 13,000 photographs from some 500 glaciers. Application of such data is illustrated using the well-documented example of the European Alps, where glaciers - like probably in many other mountain chains as well - could essentially vanish within the coming decades.
Jomelli, Vincent; Khodri, Myriam; Favier, Vincent; Brunstein, Daniel; Ledru, Marie-Pierre; Wagnon, Patrick; Blard, Pierre-Henri; Sicart, Jean-Emmanuel; Braucher, Régis; Grancher, Delphine; Bourlès, Didier Louis; Braconnot, Pascale; Vuille, Mathias
The causes and timing of tropical glacier fluctuations during the Holocene epoch (10,000 years ago to present) are poorly understood. Yet constraining their sensitivity to changes in climate is important, as these glaciers are both sensitive indicators of climate change and serve as water reservoirs for highland regions. Studies have so far documented extra-tropical glacier fluctuations, but in the tropics, glacier-climate relationships are insufficiently understood. Here we present a (10)Be chronology for the past 11,000?years (11?kyr), using 57 moraines from the Bolivian Telata glacier (in the Cordillera Real mountain range). This chronology indicates that Telata glacier retreated irregularly. A rapid and strong melting from the maximum extent occurred from 10.8?±?0.9 to 8.5?±?0.4?kyr ago, followed by a slower retreat until the Little Ice Age, about 200 years ago. A dramatic increase in the rate of retreat occurred over the twentieth century. A glacier-climate model indicates that, relative to modern climate, annual mean temperature for the Telata glacier region was -3.3?±?0.8 °C cooler at 11?kyr ago and remained -2.1?±?0.8 °C cooler until the end of the Little Ice Age. We suggest that long-term warming of the eastern tropical Pacific and increased atmospheric temperature in response to enhanced austral summer insolation were the main drivers for the long-term Holocene retreat of glaciers in the southern tropics. PMID:21654802
Nüsser, Marcus; Schmidt, Susanne
Interest in Himalayan glaciers began to spread in the era of "scientist exploration" of the South Asian high mountain belts when the three Schlagintweit brothers investigated them in 1854-1857. Their detailed records along the Himalayan arc in the form of paintings and sketch maps continue to be useful today. In later decades the glaciers of specific regions received more systematic scientific attention in the context of topographic surveys and mountaineering expeditions to the highest summits. These multipurpose missions included photogrammetrical measuring of ice movement, mapping of glaciated areas and assessments of glacier dynamics. Generally, photographic documentations were regular and integral parts of these research programs. A comprehensive collection of historical glacier photographs, taken by members of several expeditions forms a valuable baseline data set and the starting point of the present study. Our investigations seek to depict regional differences in glacier change over the last century using matched pairs of terrestrial photographs from several case studies located in the northwestern, central and eastern Himalayas: Own fieldwork between 1992 and 2012 made it possible to repeat a large number of historical glacier photographs from viewpoints identical to the earlier ones. This extensive bi-, and multi-temporal image base allows for temporal and spatial comparisons and serves to illustrate glacier dynamics, including changes in debris cover, glacier lengths, down-wasting and ice facets. Furthermore, multi-temporal and multi-scale remote sensing data were used to quantify changes of glacier lengths and glaciated areas since the 1960s.
Walder, J.S.; LaHusen, R.G.; Vallance, J.W.; Schilling, S.P.
The process of lava-dome emplacement through a glacier was observed for the first time after Mount St Helens reawakened in September 2004. The glacier that had grown in the crater since the cataclysmic 1980 eruption was split in two by the new lava dome. The two parts of the glacier were successively squeezed against the crater wall. Photography, photogrammetry and geodetic measurements document glacier deformation of an extreme variety, with strain rates of extraordinary magnitude as compared to normal alpine glaciers. Unlike normal temperate glaciers, the crater glacier shows no evidence of either speed-up at the beginning of the ablation season or diurnal speed fluctuations during the ablation season. Thus there is evidently no slip of the glacier over its bed. The most reasonable explanation for this anomaly is that meltwater penetrating the glacier is captured by a thick layer of coarse rubble at the bed and then enters the volcano's groundwater system rather than flowing through a drainage network along the bed.
Josberger, Edward G.; Bidlake, William R.; March, Rod S.; Kennedy, Ben W.
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 Glacier, Washington, and Wolverine and Gulkana Glaciers, 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 glacier mass-balance behavior, and both inter-glacier and glacier-climate relationships. South Cascade and Wolverine Glaciers 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 glaciers, with a weakening of the correlation between the winter balance fluctuations and the PDO. Non-synchronous periods of positive and negative net balance for each glacier 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 glaciers.
Schilling, S.P.; Carrara, P.E.; Thompson, R.A.; Iwatsubo, E.Y.
The cataclysmic eruption of Mount St. Helens on May 18, 1980, resulted in a large, north-facing amphitheater, with a steep headwall rising 700 m above the crater floor. In this deeply shaded niche a glacier, here named the Amphitheater glacier, has formed. Tongues of ice-containing crevasses extend from the main ice mass around both the east and the west sides of the lava dome that occupies the center of the crater floor. Aerial photographs taken in September 1996 reveal a small glacier in the southwest portion of the amphitheater containing several crevasses and a bergschrund-like feature at its head. The extent of the glacier at this time is probably about 0.1 km2. By September 2001, the debris-laden glacier had grown to about 1 km2 in area, with a maximum thickness of about 200 m, and contained an estimated 120,000,000 m3 of ice and rock debris. Approximately one-third of the volume of the glacier is thought to be rock debris derived mainly from rock avalanches from the surrounding amphitheater walls. The newly formed Amphitheater glacier is not only the largest glacier on Mount St. Helens but its aerial extent exceeds that of all other remaining glaciers combined. Published by University of Washington.
Linsbauer, Andreas; Paul, Frank; Haeberli, Wilfried
The rapid shrinkage of glaciers in the Alps has widespread impacts on relief development and hydrology. Slope failures, collapse of lateral moraines, loose debris in glacier fore-fields, new lakes and changing river beds are among the most visible impacts. They already require increased attention by tourists, monitoring by local authorities and mitigation measures (e.g. www.gletschersee.ch). A view into potential future developments (after glaciers have disappeared) is thus of high interest. With recently developed models that reconstruct glacier bed topography from easily available datasets (e.g. glacier outlines and a DEM) over entire mountain ranges, potential developments of the landscape and hydrology can be quantitatively determined. The modelled glacier beds - though they must be seen as a rough first order approximation only - also allows the investigation of a wide range of glaciological relations and dependencies that have been widely applied but were never investigated for a large sample of glaciers so far. A key reason is that information on glacier thickness distribution and total ice volume is sparse and that the future development of glaciers can only be modelled realistically when a glacier bed is available. Hence, with the glacier beds now available there is a larger number of geomorphological, glaciological and hydrological studies ahead of us. This presentation is providing an overview on the lessons learned about glaciers and their future development from the modelled glacier beds, the expected changes in hydrology (e.g. decreasing glacier volume and formation of new lakes) and potential impacts from the altered geomorphology (e.g. debuttressing of rock walls). In particular the flat tongues of larger valley glaciers are rather thick and leave oversteepened lateral moraines or rock walls behind, towering above overdeepenings in the glacier bed that might be filled with water. It is thus expected that the hazard potential will further increase in the future, partly also due to a combination of processes that can only be assessed with an integrative view that also considers the historic perspective.
William D. McCOY
01003, U.S.A. ABSTRACT Lichen measurements and other relative-age data were collected from deposits of several cirque glaciers in the Torngat Mountains of northern Labrador. Lichen growth sta tions were established, but no lichen-growth curve has yet been determined for the local area. However, moraines can be correlated between valleys on the basis of the largest diameter thallus of Rhizocarpon geographicum
Walter, J. I.; Peng, Z.; Tulaczyk, S. M.; Oneel, S.
In the solid earth community, the discovery that distant earthquakes can trigger tectonic earthquakes and tremor is perhaps attributable to the widespread use of passive seismic instrumentation. Recent increases in passive seismic infrastructure in the Polar Regions provide a similar opportunity to investigate dynamic behavior of the cryosphere on increasing spatial and temporal scales. We examine triggering of various glacier behaviors, including calving and ice flow speed increases, due to passing seismic waves from distant, large earthquakes. We observe that repeating, bidaily slip events at the Whillans Ice Plain, West Antarctica, occur faster in their cycle than otherwise predicted, shortly after the arrival of surface waves from the 2010 Maule (Chile) and 2011 Tohoku earthquakes. At various Antarctic seismic stations, we observe high frequency icequakes coincident with the arrival of compressional P wave and the Rayleigh surface waves from the 2010 Maule earthquake, suggesting an icequake source related to volumetric strain changes, such as opening of fluid-filled cracks. Finally, we observe some evidence of triggering of calving events at Columbia Glacier, Alaska. Verification that surface waves trigger calving events is difficult due to active calving before and after seismic arrivals and the long duration of the calving seismic signal. Close examination of time-lapse photos suggests that calving may occur sometime between the hourly photographs, but the coarse sampling interval precludes definitive confirmation. A number of mechanisms are plausible for triggering glacier phenomena, including basal till pore pressure changes by arriving surface waves, increasing stresses parallel or perpendicular to the axes of crevasses, and dynamically increasing the driving stress. If triggering occurs where the glacier ice is critically stressed, such that small stress perturbations from distant seismic waves produce failure, then investigating triggering may lead to a better understanding of the stress state of those systems.
Oliver Mühlmann; Ursula Peintner
The bog sedge Kobresia myosuroides is among the first ectomycorrhizal (EM) plants forming dense pads on receding glacier forefronts of the Austrian Alps. This\\u000a is the only Cyperaceae species known to form EM. To date, little is known about fungal species involved in these EM associations.\\u000a Therefore, the main aim of this study was to detect EM fungal communities of
Moffat, C. F.; Bown, F.; Iturra, C.
Quantifying the meltwater discharge from retreating glaciers, and understanding the ocean processes that influence that discharge is a key step to improve projections of sea level rise. Here, oceanographic observations collected near Jorge Montt, a rapidly retreating glacier in the Southern Patagonian Ice field, are used to (i) quantify the seasonal changes in the freshwater discharge from the glacier and the relative contribution of meltwater and runoff to it; (ii) to understand the relative role that un- or underresolved circulation processes, including tides, have on estimates of the freshwater discharge components; and (iii) to characterize the mixing processes which help explain the spatial distribution of the freshwater discharge components along the fjord. In order to quantify the freshwater discharge from the glacier, we conducted tidally-resolving, cross-channel surveys of current velocity and hydrographic profiles during summer 2013 and winter 2014. The current velocity observations were collected using a dual Acoustic Doppler Current Profiler system designed to resolve, simultaneously, the surface fresh layer and the deep, warm ocean inflow. Concurrent microstructure profiles were collected during the surveys to characterize the intensity and spatial structure of the mixing in the fjord. Additionally, along-shelf fjord surveys of water properties were conducted to provide context for the cross-channel surveys. In the context of recent idealized theoretical and numerical model work, the results highlight the importance of including ambient stratification as well the far field temperature and subsurface runoff as key parameters to understand the structure and magnitude of the freshwater outflow. They also show that freshwater (and therefore, meltwater) discharge estimates can have large biases or errors when using observations that are not tidally-resolving or that exclude the often relatively thin, fresh surface layer present in these systems.
Williamson, R. J.; Collins, D. N.
Both air temperature and incoming solar radiation influence the seasonal pattern of snow- and ice-melt in glacierised Alpine basins, so that glacier-fed rivers have distinctive regimes with more than 90% of flow occurring in the months April through October. Snow melt increases discharge slowly in April and May, before the transient snow line starts to rise, exposing glacier ice to melt and leading to flow maxima in late July/early August. Meltwater temperature is inversely related to discharge as well as being positively influenced by energy and heat availability. Close to glacier termini, water temperatures reach maxima in spring, before decreasing as the volume of water being heated increases with rising discharge. Records of meltwater temperature and discharge for rivers draining basins with between 17 and 80% glacierisation in Kantons Bern and Wallis, Switzerland, have been examined, together with measurements of radiation and 2 m air temperatures at stations close to or in the catchment areas, at hourly resolution, within the period 2003-2013. The aims were to characterise seasonal and diurnal patterns of variation of meltwater temperature and to assess impacts of energy availability, discharge, distance downstream to measurement site, and percentage cover of basin with snow and ice on temperature. On a diurnal basis, water temperature increases before discharge rises, reducing as runoff reaches daily peak. Diurnal temperature ranges are greatest during times of relatively low flows in spring. On a seasonal scale, water temperature peaks in spring before the main discharge period. Temperatures remain in relatively limited ranges, and are suppressed during high flows in the main ablation season. Summer reduction in temperature is larger the more highly glacierised the basin and the closer to the glacier terminus. A simple radiation-forced model has been used to assess relationships between discharge, water surface area, flow velocity and length of time of water exposure to energy input
Brew, David A.; Kimball, Arthur L.
Glacier Bay National Monument is a highly scenic and highly mineralized area about 100 mi west of Juneau, Alaska. Four deposits with demonstrated resources of nickel, copper, zinc, and molybdenum have been identified within the monument and eleven areas of probable or substantiated mineral-resource potential have been identified. The monument is highly mineralized in comparison with most areas of similar size elsewhere in southeastern Alaska, and present estimates of mineral resources are considered conservative.
A. M. J. Schwarz; T. G. A. Green; R. D. Seppelt
Bryophyte flushes in the vicinity of Canada Glacier in S.S.S.I. No. 12, Taylor Valley, Southern Victoria Land, were investigated in order to describe the vegetation present and to investigate factors affecting vegetation distribution. Biomass values from 950 to 1,250 g m-2 (dry weight) and vegetated areas up to 14,450 m2 indicate this is a significant area of bryophyte growth in
Eibl, E. P. S.; Bean, C. J.; Vogfjord, K. S.
Vatnajökull glacier in eastern Iceland covers five volcanic systems in which Bárdarbunga and Grimsvötn are the most active volcanoes. Whilst fluctuating ice cover mitigates against year-round near-field monitoring of the volcanoes, important information can be gleaned from stations deployed at the glacier's edge. Glacial cover significantly increases the complexity of and the solution space for observed seismic signals. For example tremor can be caused by magmatic activity, intra-glacier interactions, melt water flow or hydrothermal boiling. A better understanding of hazard requires a more indepth understanding of the signals generated by these processes at Vatnajökull. We augmented the sparse network in the region with two seven-element broad band seismometer arrays west of Vatnajökull, in Jökulheimar and near Laki respectively. Observed seismic tremor-like transients (< 2 Hz) originating from two cauldrons west of Grimsvötn are directly associated with small flooding events (jökulhaups), as subsequently confirmed by radar and hydrological observations. For larger longer duration floods dominant harmonic tremor frequencies of 2 to 4 Hz are observed, but they change in amplitude and frequency with time, likely reflecting variable feed and flow rates, associated with a moving source. Our aim is to 'fingerprint' these events such that they can be distinguished from seismic tremor signals associated with magmatic activity.
Glacier ice speed is one of the important parameters in glacier dynamics that can be extracted from satellite imagery and has been effectively obtained from two-dimensional cross correlation technique called feature tracking in common. The procedure is straightforward in principle, yet improvements that maximize success-fail rate have been sought for better result - such as image processing, filtering etc., in other word; less manual editing required one in final product. With ever increasing data archives, these improvements become critical in automatic process of large data set. In this study, the first focus is on the fullest utilization of previous result or existing other information - for example, priori velocity field and DEM respectively. This does not only confine search area but also effectively exclude non-glaciated area. The size and shape of image chip will be discussed, which has been empirically derived and used. Lastly, Effective way to fill gaps in velocity field will be introduced by assessing multiple peaks and neighboring results, instead of applying interpolation for the gaps. Major outlet glaciers in Greenland will be tested and the improvements are quantified over results from conventional correlation method.
Moholdt, Geir; Wouters, Bert; Gardner, Alex S.
Glaciers and ice caps are known to contribute significantly to present-day sea level rise, but there are still glaciated regions where little is known about modern changes in glacier mass. One of these regions is the Russian High Arctic archipelagos which has a total glaciated area of 51,500 km2. We have assessed the glacier mass budget of this region for a 6-year period between October 2003 and October 2009 using independent ICESat laser altimetry and GRACE gravimetry. Over this period we found that the archipelagos have lost ice at a rate of -9.1 ± 2.0 Gt a-1, which corresponds to a sea level contribution of 0.025 mm a-1. Approximately 80% of the ice loss came from Novaya Zemlya with the remaining 20% coming from Franz Josef Land and Severnaya Zemlya. Meteorological records of temperature and precipitation for the period 1980-2009 suggest that the recent climatic mass budget is not substantially different from the longer-term trend.
This patent describes a wind turbine. It comprises: a vertical axis rotor assembly coupled to a rotatable drive shaft for driving electrical power generating means; first wind deflector means for initially reflecting wind current into the rotor assembly; second wind deflector means to redirect the initially deflected wind current into the rotor assembly; and mounting means for mounting the first and second wind deflector means in the normal positions. The mounting means including an outer shaft through which the drive shaft extends and which is normally fixed with respect thereto. The outer shaft having at least one lower groove winding in one of a left-hand or right-hand direction, at least one lower groove constituting a first lower groove set, and at least one upper groove winding in the other of the left-hand or right-hand direction, at least one upper groove constituting a second upper groove set, and first lower and second upper connector rings coupled to the first and second wind deflector means respectively, and mounted on the outer shaft proximate to the first and second groove sets respectively. The first and second connector rings including guide means cooperating with at least one groove of the first and second groove sets respectively. The mounting means allowing at least one of the first and second wind deflector means to automatically move relative to each other and from its respective normal position when the velocity of the wind current exceeds a first predetermined value to increase the inter-deflector spacing and causing at least one of the first and second wind deflector means to automatically return to its respective normal position when the velocity of the wind current diminishes to a value below the first predetermined value.
Stefan Winkler; John A. Matthews; Richard A. Shakesby; P. Quentin Dresser
Moraine sequences in front of seven relatively low-altitude glaciers in the Breheimen region of central southern Norway are described and dated using a multi-proxy approach to moraine stratigraphy. Lichenometric dating, based on the Rhizocarpon subgenus, is used to construct a composite moraine chronology, which indicates eight phases of synchronous moraine formation: AD 1793-1799, 1807-1813, 1845-1852, 1859-1862, 1879-1885, 1897-1898, 1906-1908 and
Degenhardt, John Jerome
glacier settles during periods of melting, and the mode of deformation. A better understanding of these factors is important for engineers, engineering geologists and geomorphologists who must make prudent evaluations of rock glaciers as potential sites...
Jorgensen, William Revis
the physics behind the movement and internal deformation of rock glaciers. For years researchers had no access to the internal makeup of rock glaciers. Thus, proposed models and discussion have been based on theoretical concepts of electromagnetic (EM) wave...
Paris-Sud XI, Université de
USING QUAD-POL AND SINGLE-POL RADARSAT-2 DATA FOR MONITORING ALPINE AND OUTLET ANTARCTIC GLACIERS displacement fields estimations results on RADARSAT-2 (RS2) data acquired on three glaciers. 2. DISPLACEMENT
Bodkin, J.L.; Kloecker, K.A.; Esslinger, G.G.; Monson, D.H.; DeGroot, J.D.; Doherty, J.
Following translocations to the outer coast of Southeast Alaska in 1965, sea otters have been expanding their range and increasing in abundance. We began conducting surveys for sea otters in Cross Sound, Icy Strait, and Glacier Bay, Alaska in 1994, following initial reports (in 1993) of their presence in Glacier Bay. Since 1995, the number of sea otters in Glacier Bay proper has increased from around 5 to more than 1500. Between 1993 and 1997 sea otters were apparently only occasional visitors to Glacier Bay, but in 1998 long-term residence was established as indicated by the presence of adult females and their dependent pups. Sea otter distribution is limited to the Lower Bay, south of Sandy Cove, and is not continuous within that area. Concentrations occur in the vicinity of Sita Reef and Boulder Island and between Pt. Carolus and Rush Pt. on the west side of the Bay (Figure 1). We describe the diet of sea otters during 2001 in Glacier Bay based on visual observations of prey during 456 successful forage dives. In Glacier Bay, diet consisted of 62% clam, 15% mussel, 9% crab, 7% unidentified, 4& urchins, and 4% other. Most prey recovered by sea otters are commercially, socially, or ecologically important species. Species of clam include Saxidomus gigantea, Protothaca staminea, and Mya truncata. Urchins are primarily Strongylocentrotus droebachiensis and the mussel is Modiolus modiolus. Crabs include species of three genera: Cancer, Chinoecetes, and Telmessus. Although we characterize diet at broad geographic scales, we found diet to vary between sites separated by as little as several hundred meters. Dietary variation among and within sites can reflect differences in prey availability and individual specialization. We estimated species composition, density, biomass, and sizes of subtidal clams, urchins, and mussels at 9 sites in lower Glacier Bay. All sites were selected based on the presence of abundant clam siphons. Sites were not selected to allow inference to any area larger than the sampling area (approx 400 m^2). Sites were selected to achieve a broad geographic sample of dense subtidal clam beds within Glacier Bay prior to occupation and foraging by sea otters. There was no direct evidence of otter foraging at any of our clam sampling sites. We sampled 11,568 bivalves representing 14 speces of clam and 2 species of mussel. We sampled 4,981 urchins, all Strongylocentrotus droeobachiensis. Only four species of clam (littleneck clams, Protothaca staminea; butter clams, Saxidomus gigantea; soft-shell claims, Mya truncata; and Macoma sp.) accounted for 91.6% of all clams sampled. Mean total clam density (#/0.25 m^2) across the 9 sites was 62.3. Densities (and se ) of P. staminea averaged 22.6 (1.6) and ranged from 0 to 97. Densities of S. gigantea averaged 14.4 (1.0) and ranged from 0 to 63. Densities of Macoma sp. averaged 14.5 (1.2) and ranged from 0 to 78. Densities of S. droebachiensis averaged 27.3 (1.7) and ranged from 0 to 109. Mean S. droebachiensis sizes ranged from 16 to 30 mm by site. Mean P. staminea sizes ranged from 30 to 53 mm, mean S. gigantea sizes ranged from 51 to 85 mm, and mean Macoma sp. sizes ranged from 14 to 19 mm. Although not the most abundant clam, S. gigantea contributed the greatest proportion to total clam biomass (63%), followed by P. staminea (24%). Sea otters are now well established in limited areas of the lower portions of Glacier Bay. It is likely that distribution and numbers of sea otters will continue to increase in Glacier Bay in the near future. Glacier Bay supports large and diverse populations of clams that are largely unexploited by sea otters presently. It is predictable that the density and sizes of clam populations will decline in response to otter predation. This will result in fewer opportunities for human harvest, but will also trigger ecosystem level changes, as prey for other predators, such as octopus, sea stars, fishes, birds and mammals are modified. Sea ott
Gourmelen, N.; Dehecq, A.; Trouvé, E.
Climate warming over the 20th century has caused drastic changes in mountain glaciers globally, and of the Himalayan glaciers in particular. The stakes are high; glaciers and ice caps are the largest contributor to the increase in the mass of the world's oceans, and the Himalayas play a key role in the hydrology of the region, impacting on the economy, food safety and flood risk. Partial monitoring of the Himalayan glaciers has revealed a mixed picture; while many of the Himalayan glaciers are retreating, in some cases locally stable or advancing glaciers in this region have also been observed. But recent controversies have highlighted the need to understand the glaciers dynamic and its relationship with climate change in the region. Earth Observation provides a mean for global and long-term monitoring of mountain glaciers' dynamics. In the frame of the Dragon program, a partnership between the European Space Agency (ESA) and the Chinese Center for Earth Observation (NRSCC), we begun a monitoring program aimed at quantifying multidecadal changes in glaciers' flow at the scale of the entire Himalayas and Karakoram from a 40 years' archive of Earth Observation. Ultimately, the provision of a global and time-sensitive glaciers velocity product will help to understand the evolution of the Himalayan glaciers in lights of glaciological (e.g. presence of debris-cover, surges, proglacial lakes) and climatic conditions. Here we present a region-wide analysis of annual and seasonnal glacier flow velocity covering the Pamir-Karakoram-Himalaya region obtained from the analysis of the entire archive of Landsat data. Over 90% of the ice-covered regions, as defined by the Randolph Glacier Inventory, are measured, with precision on the retrieved velocity of the order of 2 m/yr. We show that the first order temporal evolution of glacier flow mirrors the pattern of glacier mass balance. We observe a general decrease of ice velocity in regions of known ice mass loss, and a more complex patterns consisting of mixed acceleration and decrease of ice velocity in regions that are known to be affected by stable mass balance and surge-like behavior.
Maurer, Malyssa K.; Menounos, Brian; Luckman, Brian H.; Osborn, Gerald; Clague, John J.; Beedle, Matthew J.; Smith, Rod; Atkinson, Nigel
Castle Creek Glacier in the Cariboo Mountains of British Columbia remained close to its Little Ice Age limit for most of the past 1500 years, without significant recession until the 20th century. This conclusion is based on radiocarbon-dated detrital and in-situ plant material overrun by the glacier, and the sedimentary record from informally named On-off Lake, which received clastic sediments only when Castle Creek Glacier crossed a hydrologic divide 330 m upvalley of the Little Ice Age limit. Plant macrofossils recovered from the transition between basal inorganic silt and overlying organic silty clay in a sediment core from the lake indicate that the glacier first retreated behind the divide ca. 10.92-9.70 ka. Ages of 8.97-8.61 and 5.58-5.53 ka on detrital wood from the glacier's forefield may record earlier advances, but the first unequivocal evidence of glacier expansion is from an overridden stump with an age of 4.96-4.45 ka. Continuous accumulation of gyttja within On-off Lake, however, indicates that Castle Creek Glacier did not cross the hydrologic divide at any time during the first half of the Holocene. Glacigenic sediments began to accumulate in the lake between 2.73 and 2.49 ka, indicating that Castle Creek Glacier expanded beyond the hydrologic divide at that time. A coincident advance is also recorded in the northern Rocky Mountains of British Columbia at Kwadacha Glacier, which overran a vegetated surface at 2.69-2.36 ka. Clastic sedimentation in On-off Lake ceased soon after the Bridge River volcanic eruption (2.70-2.35 ka), indicating that Castle Creek glacier retreat to a position upvalley of the divide at that time. Sedimentation resumed before 1.87-1.72 ka when the glacier advanced again past the hydrologic divide. Following a second retreat, Castle Creek Glacier advanced across the divide a final time at ca. 1.54-1.42 ka. The snout of the glacier remained less than 330 m upvalley of the Little Ice Age moraine until the early twentieth century when annual moraines indicate rapid frontal recession to a position upvalley of the hydrologic divide. These data collectively indicate that glaciers in the Cariboo Mountains of British Columbia nearly achieved their all-time Holocene limits as early as 2.73-2.49 ka and climatic conditions in the early 20th century abruptly ended a 1500-year period favoring glacier expansion.
Langhammer, Lisbeth; Rabenstein, Lasse; Bauder, Andreas; Lathion, Patrick; Maurer, Hansruedi
In the recent years the bedrock topography of the Swiss Alpine Glaciers has been mapped by ground-based and helicopter-borne GPR (Ground Penetrating Radar) as part of an ongoing comprehensive inventory initiated by the ETH Zürich, the Swiss Competence Center for Energy Research (SCCER) and the Swiss Geophysical Commission (SGPK). Our recorded GPR data of glacier bedrock topography highlights the need of a better understanding of the interaction between GPR systems and the glacierized subsurface in high mountain terrain. The Otemma glacier in the Pennine Alps, Valais, has been subject to repeated profiling with commercial GPR ground units (pulseEKKO and GSSI) operating at frequencies ranging from 15-67 MHz deployed at the surface and mounted on a helicopter. Our data shows significant quality differences between similar GPR profiles, which could not be explained by system failure or technical discrepancies. To investigate the issue, we conducted antenna rotation experiments at several locations on the glacier surface. The results indicate a strong relationship between the orientation of the bistatic antennas and the flow direction of the glacier. Possible explanation for our observations range from anisotropy effects in glacier ice, the influence of directional characteristics of the GPR antennas or distinctive features of the bedrock topography. To explain our results, we perform 3D GPR modeling of the glacier body with the FDTD electromagnetic simulator gprMax. A basic homogenous three-dimensional model of the glacier will be replaced by varying bedrock topography along a transect. Internal structures such as water layers and inclusion will be imbedded in the simulations. Currently ground based GPR surveys produce higher quality data with respect to the visibility of glacier bed reflections. We intent to enhance our operating system and antenna installation on the helicopter based on the results of the simulations to achieve similar quality standards. The objective is to successfully map the bedrock topography of the Swiss glaciers in the next three years.
Hambrey, Michael J.; Quincey, Duncan J.; Glasser, Neil F.; Reynolds, John M.; Richardson, Shaun J.; Clemmens, Samuel
This paper presents the sediment, landform and dynamic context of four avalanche-fed valley glaciers (Khumbu, Imja, Lhotse and Chukhung) in the Mount Everest (Sagarmatha) region of Nepal. All four glaciers have a mantle of debris dominated by sandy boulder-gravel that suppresses melting to an increasing degree towards the snout, leading to a progressive reduction in the overall slope of their longitudinal profile. Prominent lateral-terminal moraine complexes, also comprising sandy bouldergravel, enclose the glaciers. These terminal moraines originally grew by accretion of multiple sedimentary facies of basal glacial and supraglacial origin, probably by folding and thrusting when the glaciers were more dynamic during the Little Ice Age. The four glaciers are in various stages of recession, and demonstrate a range of scenarios from down-wasting of the glacier tongue, through morainedammed lake development, to post-moraine-dam breaching. Khumbu Glacier is at the earliest stage of supraglacial pond formation and shows no sign yet of developing a major lake, although one is likely to develop behind its >250 m high composite terminal moraine. Imja Glacier terminates in a substantial body of water behind a partially ice-cored moraine dam (as determined from geophysical surveys), but morphologically appears unlikely to be an immediate threat. Chukhung Glacier already has a breached moraine and a connected debris fan, and therefore no longer poses a threat. Lhotse Glacier has an inclined, free-draining tongue that precludes hazardous lake development. From the data assembled, a conceptual model, applicable to other Himalayan glaciers, is proposed to explain the development of large, lateral-terminal moraine complexes and associated potentially hazardous moraine dams. - 2008 Elsevier Ltd. All rights reserved .
Hambrey, Michael J.; Quincey, Duncan J.; Glasser, Neil F.; Reynolds, John M.; Richardson, Shaun J.; Clemmens, Samuel
This paper presents the sediment, landform and dynamic context of four avalanche-fed valley glaciers (Khumbu, Imja, Lhotse and Chukhung) in the Mount Everest (Sagarmatha) region of Nepal. All four glaciers have a mantle of debris dominated by sandy boulder-gravel that suppresses melting to an increasing degree towards the snout, leading to a progressive reduction in the overall slope of their longitudinal profile. Prominent lateral-terminal moraine complexes, also comprising sandy boulder-gravel, enclose the glaciers. These terminal moraines originally grew by accretion of multiple sedimentary facies of basal glacial and supraglacial origin, probably by folding and thrusting when the glaciers were more dynamic during the Little Ice Age. The four glaciers are in various stages of recession, and demonstrate a range of scenarios from down-wasting of the glacier tongue, through moraine-dammed lake development, to post-moraine-dam breaching. Khumbu Glacier is at the earliest stage of supraglacial pond formation and shows no sign yet of developing a major lake, although one is likely to develop behind its >250 m high composite terminal moraine. Imja Glacier terminates in a substantial body of water behind a partially ice-cored moraine dam (as determined from geophysical surveys), but morphologically appears unlikely to be an immediate threat. Chukhung Glacier already has a breached moraine and a connected debris fan, and therefore no longer poses a threat. Lhotse Glacier has an inclined, free-draining tongue that precludes hazardous lake development. From the data assembled, a conceptual model, applicable to other Himalayan glaciers, is proposed to explain the development of large, lateral-terminal moraine complexes and associated potentially hazardous moraine dams.
A wind turbine is described comprising: a vertical axis rotor assembly coupled to a rotatable drive shaft for driving electrical power generating means; first wind deflector means mounted on the wind turbine normally positioned generally upwind and to one side of the rotor assembly for initially deflecting wind current into the rotor assembly and second wind deflector means mounted on the wind turbine normally positioned on another side of the rotor assembly to redirect the initially deflected wind current into the rotor assembly. The first and second wind deflector means are normally spaced from each other by a certain inter-deflector spacing; mounting means for mounting the first and second wind deflector means in the normal positions, the mounting means including an outer shaft through which the drive shaft extends and which is normally fixed with respect thereto. The outer shaft has an upwardly facing circumferentially extending shoulder formed therein including a first shoulder portion extending around a major portion of the circumference of the outer shaft and a pair of upwardly sloping portions which reet at an apex.
York, A.; Frey, K. E.; Das, S. B.; Evans, M. J.; Gardner, A. S.; Smith, B. E.; Trusel, L. D.
The variability in outlet glacier termini positions is an important indicator of overall glacier health and the net effects of ice-ocean-atmosphere interactions. Glacier margins fluctuate on both seasonal and interannual time scales, and owing to logistical difficulties associated with field observations, satellite imagery provides a critical spatially- and temporally-extensive resource for monitoring glacier behavior. In general, outlet glacier termini have been retreating globally over recent decades, but the magnitude of seasonal variation and overall retreat has proven unique to each glacier. The outlet glaciers in central West Greenland are generally experiencing the same regional atmospheric forcing, yet previous studies have shown varying magnitudes of retreat over the last forty years. Such observations point to the importance of local-scale forcing on outlet glacier dynamics. In this study, we utilized Landsat imagery between the years 1985 and 2014 to digitize a time series of glacier front positions of 18 outlet glaciers in the Disko and Uummannaq Bay regions of West Greenland. We additionally examined glacier terminus dynamics in context with proximal sea ice conditions (using SMMR, SSM/I and AMSR-E passive microwave-based sea ice concentrations) to assess the potential influence of ice mélange on terminus behavior. High-resolution WorldView satellite-based digital elevation models provide ancillary data that allow for investigation of the influence of ice mélange thickness on outlet glacier behavior across the region. Our findings suggest that the magnitude of seasonal variation in terminus position can be indicative of longer-term trends in glacier behavior. Furthermore, our results indicate that that duration of sea ice cover acts as a limiting force on the ability of a glacier to accelerate until the clearing of its mélange-filled fjord. These findings underscore the importance of glacier and fjord geometries in modulating glacier retreat across West Greenland.
Maurer, J. M.; Rupper, S.
Himalayan glaciers are important natural resources and climatic indicators. Many of these glaciers have debris-covered ablation zones, while others are mostly clean ice. Regarding glacier dynamics, it is expected that debris-covered glaciers will respond differently to atmospheric warming compared to clean ice glaciers. In the Bhutanese Himalaya, there are (1) north flowing clean-ice glaciers with high velocities, likely with large amounts of basal sliding, and (2) south flowing debris-covered glaciers with slow velocities, thermokarst features, and influenced more by the Indian Summer Monsoon. This region, therefore, is ideal for comparing the dynamical response of clean-ice versus debris-covered glaciers to climatic change. In particular, previous studies have suggested the north flowing glaciers are likely adjusting more dynamically (i.e. retreating) in response to climate variations, while the south flowing glaciers are likely experiencing downwasting, with stagnant termini locations. We test this hypothesis by assessing glacier changes over three decades in the Bhutan region using a newly-developed workflow to extract DEMs and orthorectified imagery from both 1976 historical spy satellite images and 2006 ASTER images. DEM differencing for both debris-covered and clean glaciers allows for quantification of glacier surface elevation changes, while orthorectified imagery allows for measuring changes in glacier termini. The same stereo-matching, denoising, and georeferencing methodology is used on both datasets to ensure consistency, while the three decade timespan allows for a better signal to noise ratio compared to studies performed on shorter timescales. The results of these analyses highlight the similarities and differences in the decadal response of clean-ice and debris-covered glaciers to climatic change, and provide insights into the complex dynamics of debris-covered glaciers in the monsoonal Himalayas.
Meier, Mark Frederick; Tangborn, Wendell V.; Mayo, Lawrence R.; Post, Austin
Glaciers occur in northwestern North America between lat 37 deg and 69 deg N. in two major mountain systems. The Pacific Mountain System, near the west coast, receives large amounts of precipitation, has very mild temperatures, and contains perhaps 90 percent of the glacier ice. The Rocky Mountain or Eastern System, on the other hand, receives nearly an order of magnitude less precipitation, has temperatures that range from subpolar to subtropic, and contains glaciers that are much smaller in both size and total area. As a contribution to the International Hydrological Decade program on combined balances at selected glaciers, the U.S. Geological Survey is conducting studies of ice and water balance on four glaciers in the Pacific Mountain System: Wolverine and Gulkana Glaciers in Alaska, South Cascade Glacier in Washington, and Maclure Glacier in California. Similar data are being collected by other organizations at five glaciers in western Canada, including two in the Rocky Mountain System, and at one glacier in the Rocky Mountain System in northern Alaska. Gulkana, Wolverine, South Cascade, and Maclure Glaciers have dissimilar mass balances, and each is fairly representative of the glaciers for its particular region. Gulkana Glacier (lat 63 deg 15' N., Alaska Range, Alaska) normally has an equilibrium line at an altitude of 1,800 m (meters), an activity index of about 6 mm/m (millimeters per meter), a winter balance of about 1.0 m, and an annual exchange of about 2.2 m. (Balance values are given in terms of water-equivalent measure; the winter balance of 1 m, for example, indicates a volume of ice equal in mass to a volume of water 1 m in depth covering the area of the glacier.) The normal approximate parameters for the other glaciers studied are as follows: Wolverine Glacier (lat 60 deg 24' N., Kenai Mountains, Alaska) - equilibrium-line altitude 1,200 m, activity index 9 mm/m, winter balance 2.5 m, and annual exchange 5.5 m; South Cascade Glacier (lat 48 deg 22' N., North Cascades, Wash.) - equilibrium-line altitude 1,900 m, activity index 17 mm/m, winter balance 3.1 m, and annual exchange 6.6 m; and Maclure Glacier (lat 37 deg 45' N., Sierra Nevada, Calif.) - equilibrium-line altitude 3,600 m, activity index 23 mm/m, winter balance 2.3 m, and annual exchange 4.6 m. Mass balances of these four glaciers and their drainage basins are measured annually by standard glaciological techniques. In addition, the hydrologic balance is calculated using streamflow and precipitation measurements. Combining these independent measurements results in fairly well defined values of water and ice balance for the glaciers and drainage basins. A revision of the standard International Hydrological Decade mass-balance system permits combination of annual and stratigraphic terms. The annual balance of South Cascade Glacier at the end of the 1965 hydrologic year was slightly positive (+0.07 m averaged over the glacier), but continued ablation and deficient accumulation in October 1965 resulted in slightly negative net balances for both the glacier and the drainage basin. Factors tending to produce this near-zero balance were the above-average late-winter balance (3.48 m) and the numerous summer snowfalls. Ice ablation averaged about 39 mm of water per day during the main melt season. Runoff during the summer ablation season was lower than the 1958-64 average. The South Cascade Glacier annual balance in 1966 (-0.94 m) was considerably more negative mainly owing to the deficient winter snowpack (the late-winter balance was only 2.52 m) and the warm dry summer. Ice ablation averaged about 44 mm of water per day during the melt season. The loss in storage of this and other glaciers in the North Cascades increased the runoff of many valley streams by approximately 50 percent during August and September. The 1966 Gulkana Glacier annual balance was slightly positive (+0.06 m); on the basis of past observations and the rapid terminus ret
A. Ikeda; K. Yoshikawa
The relationship between debris supply and the size of rock glaciers is discussed through a topographical analysis of a number of rock glaciers and their debris sources (i.e. rockwalls) in the central Brooks Range, Alaska, an area characterised by simple geology and continuous permafrost. The measured topographical parameters, such as lengths, areas and slope angles for the rock glaciers and
Smith, B. E.
In response to the ongoing mass loss from the Amundsen Sea sector of Antarctica, Operation Ice Bridge has made a directed effort in 2009 and 2010 to measure surface elevation changes on Pine Island, Thwaites, and Smith glaciers. Previous satellite radar interferometry measurements have shown relatively steady flow on Thwaites glacier, a continuous acceleration of Pine Island Glacier, and show that Smith Glacier had a similar overall fractional acceleration to Pine Island between 1996 and the present; however, published velocity measurements do not clearly show the timing of the acceleration of Smith Glacier. In this presentation, we use a combination of ICESat, pre-OIB laser altimetry data, and OIB laser altimetry data to estimate patterns in surface elevation change for these three glaciers, and their temporal variations. On Thwaites Glacier, we see steady thinning, reflecting the largely constant flow field upstream of the grounding line. By contrast, on Pine Island glacier, we see strong thinning confined near the grounding in 2003-04, followed by inward-spreading pattern of thinning that continues to the present. On Smith glacier, the pattern of elevation change is similar to that in Pine Island glacier, with large thinning rates near the grounding line early in the ICESat mission, followed by increased thinning farther inland. This suggests that the ice speed changes in Smith Glacier followed a similar temporal pattern to those in Pine Island, and demonstrates strong similarities between the responses of these two glaciers to ice plain ungrounding.
In the North Cascade Range, Washington snowpack accumulation and the resultant ablation provides critical summer water resources. Direct measurement of ablation on the Easton Glacier during 2002 and 2003 allowed determination of glacier runoff from the adjacent Deming Glacier. The summer of 2002 was relatively cool and wet and followed a wet winter, as a result the contribution of the
Glacier mass balance variability in the Cordillera Blanca, Peru and its relationship with climate the Cordillera Blanca, Peru, was investigated for its climate sensitivity toward temperature, humidity reserved. Keywords: Andes; glaciers; climate change; ENSO 1. Introduction Glaciers in the Andes of Peru
David J. Barclay; Parker E. Calkin; Gregory C. Wiles
Stratigraphic and geomorphic data de- fined by radiocarbon ages, tree-ring dates, and historical observations provide evi- dence of three major Holocene expansions of Hubbard Glacier. Early in each advance the Hubbard Glacier margin blocked Rus- sell Fiord to create Russell lake, raising base level and causing stream beds and fan deltas throughout the Russell drainage ba- sin to aggrade. Each
D. B. Fagre
The impact of climate change on mountain watersheds has been studied at Glacier National Park, Montana since 1991. Despite a 14% increase in annual precipitation, glaciers have receded, snow packs have diminished, and late season stream discharge has declined. Snow melts one month earlier in the spring, leading to earlier hydrologic peaks and tree invasions of subalpine meadows. This has
Marzeion, B.; Jarosch, A. H.; Hofer, M.
We present a model of the global surface mass balance of glaciers, based on the reconstruction and projection of the surface mass balance of all the world's individual glaciers. The model is validated using a leave-one-glacier-out cross validation scheme using 3997 observed surface mass balances of 255 glaciers, and against 756 geodetically observed, temporally integrated volume and surface area changes of 341 glaciers. Between 1902 and 2009, the world's glaciers are reconstructed to have lost mass corresponding to 114 ± 5 mm sea level equivalent (SLE). During the 21st century, they are projected to loose additionally between 148 ± 35 mm SLE (scenario RCP26), 166 ± 42 mm SLE (scenario RCP45), 175 ± 40 mm SLE (scenario RCP60), to 217 ± 47 mm SLE (scenario RCP85). Based on the extended RCP scenarios, glaciers are projected to approach a new equilibrium towards the end of the 23rd century, after having lost between 248 ± 66 mm SLE (scenario RCP26), 313 ± 50 mm SLE (scenario RCP45), to 424 ± 46 mm SLE (scenario RCP85). Up until approximately 2100, ensemble uncertainty within each scenario is the biggest source of uncertainty for the future glacier mass loss; after that, the difference between the scenarios takes over as the biggest source of uncertainty. Rates of mass loss are projected to peak between 2050 and 2100, depending on the scenario.
J. SMITH; Joseph R. DESLOGES; D. J. SMITH
This paper describes licheno- metric and dendroglaciological investigations of Little Ice Age (LIA) deposits at Tzeetsaytsul Glacier, Tweedsmuir Provincial Park, British Columbia. The glacier originates from an ice- field on the northeast flank of Tzeetsaytsul Peak and terminates in a moraine-dammed lake. A stream draining the lake has incised the moraine dam and flows through nested moraines into a second
. On the Murtèl rock glacier, Rhizocarpon geographicum thalli with a diameter >4cm occur on surfaces with ages, pioneer plants, Rhizocarpon geographicum, permafrost, Upper Engadin (Canton of Grisons, Switzerland as an additional method on Murtèl rock glacier and on the protalus rampart. Measurements of Rhizocarpon
Samantha J. Hamilton; W. Brian Whalley
Preliminary results from the lichenometric dating studies undertaken using the collective lichen “species” Rhizocarpon geographicum sensu lato are presented and applied to the establishment of a rock glacier developmental chronology for the Nautardálur rock glacier, Tröllaskagi, northern Iceland. Absolute dates are tentatively postulated based on the application of the largest lichen thalli diameters to a regional Trollaskagi R. geographicum s.l.
Nozomu Takeuchi; Shiro Kohshima
We quantitatively investigated a snow algal community on Tyndall Glacier of the Southern Patagonia Icefield, Chile, at an elevation from 300 to 1500 m a.s.l. We observed 7 species of snow and ice algae (Chlorophyta and cyanobacteria) on the glacier. These species were Mesotaenium (M.) berggrenii, Cylindrocystis (Cyl.) brebissonii, Ancylonema sp., Closterium sp., Chloromonas sp., Oscillatoriaceae cyanobacterium, and an unknown
R. J. Motyka; M. Truffer; R. D. Powell
One of the most important unresolved questions concerning temperate tidewater glaciers is the role that submarine melting and proglacial convection play in controlling terminus stability. Little is known about ocean thermal forcing of temperate tidewater glaciers even though its seasonal and long-term variation may significantly influence calving speed, terminus dynamics and ocean convection. Relationships developed from field, experimental, and analytical
Larsen, C.F.; Motyka, R.J.; Arendt, A.A.; Echelmeyer, K.A.; Geissler, P.E.
The digital elevation model (DEM) from the 2000 Shuttle Radar Topography Mission (SRTM) was differenced from a composite DEM based on air photos dating from 1948 to 1987 to detennine glacier volume changes in southeast Alaska and adjoining Canada. SRTM accuracy was assessed at ??5 in through comparison with airborne laser altimetry and control locations measured with GPS. Glacier surface elevations lowered over 95% of the 14,580 km2 glacier-covered area analyzed, with some glaciers thinning as much as 640 in. A combination of factors have contributed to this wastage, including calving retreats of tidewater and lacustrine glaciers and climate change. Many glaciers in this region are particularly sensitive to climate change, as they have large areas at low elevations. However, several tidewater glaciers that had historically undergone calving retreats are now expanding and appear to be in the advancing stage of the tidewater glacier cycle. The net average rate of ice loss is estimated at 16.7 ?? 4.4 km3/yr, equivalent to a global sea level rise contribution of 0.04 ?? 0.01 mm/yr. Copyright 2007 by the American Geophysical Union.
Rignot, E. J.; Fenty, I. G.; Xu, Y.; Cai, C.; Aykutlug, E.; Dupont, T. K.
Very few attempts have been made to map the submerged calving face of tidewater glaciers in the past. Here, we present results from the August 2012 and 2013 campaigns in West Greenland where we visited several glaciers in Atasund, Torssukataq, Uummannaq and Upernavik Fjords. We employ a low frequency multibeam sonar tilted to the side to image the side walls of the glacial fjords, including the submerged calving faces. The results reveal the true depth of the grounding line of these glaciers, which is typically unknown - or known with enormous uncertainties - from traditional ship soundings or from the mapping of glacier thickness, the general shape and slope of the submerged calving fronts, and the presence and spatial distribution of channels of subglacial water discharge that fuel high rates of ice face melting. By repeating the mapping over time on a few glaciers and compensating the data for ice motion, we are able to calculate calving rates and ice melt rates over periods of a few days and compare the ice melt production results with estimates derived from hydrographic surveys. In most examples, knowledge of the sea floor topography is the principal information retrieved from these surveys because it determines whether subsurface warm waters can access the glacier face, but the spatial imaging of the submerged calving face reveals spatial details about ice-ocean interactions that are fundamental to the process of ice melt and complex. Such mappings should be extended to other glaciers and eventually to all tidewater glaciers in Greenland.
G. Warner; G. Cloud
Natural scientists and engineers are continuing to seek an understanding of the mechanism of flow and deformation of glaciers. A necessary component of this exploration is the accurate determination of strain rates in glacier ice. The purpose of this investigation was to develop a strain-measuring method which is dependable and precise under difficult field conditions.The measuring technique which was developed
Ballantyne, C.K.; Hall, A.M.; Phillips, W.; Binnie, S.; Kubik, P.W.
Geomorphological mapping provides evidence for two former low-level corrie glaciers on Hoy, both defined by end moraines. Five 10Be exposure ages obtained from sandstone boulders on moraine crests fall within the range 12.4??1.5 ka to 10.4??1.7 ka (weighted mean 11.7??0.6 ka), confirming that these glaciers developed during the Loch Lomond (Younger Dryas) Stade (LLS) of 12.9-11.5 cal. ka BP, and demonstrate the feasibility of using this approach to establish the age of LLS glacier limits. The equilibrium line altitude (ELA) of one of the glaciers (99 m) is the lowest recorded for any LLS glacier, and the area-weighted mean ELA for both (141 m) is consistent with a general northward ELA decrease along the west coast of Britain. The size of moraines fronting these small (???0.75 km2) glaciers implies that glacier termini remained at or close to their limits for a prolonged period. The apparent restriction of LLS glaciers to only two sites on Hoy probably reflects topographic favourability, and particularly the extent of snow-contributing areas.
de Juan, J.; Elosegui, P.; Nettles, M.; Larsen, T. B.; Davis, J. L.; Hamilton, Gordon S.; Stearns, Leigh; Anderson, M. L.; Ekstrom, G.; Ahlstrom, A. P.; Stenseng, L.; Khan, S. A.; Forsberg, R.
), with the exception of small tsunamis caused by the calving process [Nettles et al., 2008] that attenuate well before the tidal response recovers. 4. Discussion and Conclusions  Our results indicate a temporal relationship between the glacier’s enhanced response...
G. S Boulton; K. E Dobbie; S Zatsepin
The extent and style of shear deformation in sediments beneath modern glaciers and the geological evidence for such deformation in deposited sediments are reviewed. New evidence is presented from beneath a modern glacier of the spatial and temporal patterns of water pressure fluctuation and of time dependent patterns of deformation in sediments. It is concluded that in most experimental sites
Kansas, University of
Radar Sounding of Glaciers in Greenland C. Allen, B, Wohletz, and S, Gogineni The University on several flights over Greenland glaciers during the summer of 1995. The radar data were collected the theory and present results of the homomorphic deconvolution procedure. INTRODUCTION The Greenland
Howat, Ian M.
Submarine melt rate estimates for floating termini of Greenland outlet glaciers (20002010) Ellyn M. The rate of mass loss from the Greenland ice sheet has increased over the past decade due, in large part-terminating outlet glaciers in Greenland on a semi-annual basis between 2000 and 2010. We assess temporal and spatial
On the accuracy of glacier outlines derived from remote-sensing data F. PAUL,1 N.E. BARRAND,2 S) and medium-resolution (30 m) remote-sensing data, against each other and to glacier outlines derived from.g. from higher-resolution sensors) are seldom available. Moreover, after the required manual correction
The avalanche climate of Glacier National Park, B.C., Canada during 1965-2011 Sascha Bellaire 1 and evolution of the seasonal mountain snow cover and therefore determine the avalanche hazard. For this study we analyzed long-term weather data as well as snow and avalanche data from Glacier National Park
Avalanche Forecasting for Transportation Corridor and Backcountry in Glacier National Park (BC, 2500 University Drive NW Calgary AB T2N 1N4, Canada David Skjonsberg Avalanche Control, Mt. Revelstoke and Glacier National Parks, PO Box 350 Revelstoke BC V0E 2S0, Canada ABSTRACT. The Avalanche Control Section
G. H. Denton; C. H. Hendy
A corrected radiocarbon age of 11,050 [+-] 14 years before present for an advance of the Franz Josef Glacier to the Waiho Loop terminal moraine on the western flank of New Zealand's Southern Alps shows that glacier advance on a South Pacific island was synchronous with initiation of the Younger Dryas in the North Atlantic region. Hence, cooling at the
Schueller, Felix; Förster, Kristian; Hanzer, Florian; Huttenlau, Matthias; Marzeion, Ben; Strasser, Ulrich; Achleitner, Stefan; Kirnbauer, Robert
Glacier and snow runoff in high alpine regions is an essential process in hydrological research for its high relevance on lower altitude areas and hydro-power generation. MUSICALS II (Multiscale Snow/Icemelt Discharge Simulations into Alpine Reservoirs) seeks to identify and quantify water availability and runoff in alpine headwater catchments. The focus is on future changes due to glacier retreat, altering the multi-day and seasonal runoff available for hydropower operations. Our aim is to investigate and improve runoff forecasts by coupling the semi-distributed hydrological model HQSim with a simple glacier evolution model. The glacier model MMBM (Marzeion Mass Balance Model) with its statistical nature allows for fast modelling of the dynamical properties of glaciers. We present the design of the coupled hydrological application for different hydro power headwater catchments in Tyrol. The capabilities of the glacier model to simulate the selected glaciers is shown. Simulated discharge with the original and the coupled model are compared to downstream gauge measurements. Using the multi-objective optimization algorithm AMALGAM (A Multi-ALgorithm, Genetically Adaptive Multiobjective model), we optimize the glacier module parameters fully automatically. The results show the improvements in runoff modelling for past periods, when altering of glaciated catchment parts is considered. This indicates consideration of this process is mandatory for simulating future developments.
Kincaid, Joni L.
-19th century has continued. Between 1972 (Allison, 1974; Allison and Peterson, 1976) and 2000, the glaciers lost approximately 67.6% of their area, representing a reduction in surface ice area from 7.2 km2 to 2.35 km2. From 2000 to 2005, the glaciers...
Seifert, F.; Bassis, J. N.; Galey, C. E.; Jacobs, S.
Mass loss from the Greenland ice Sheet is primarily through the dynamic changes of its marine terminating outlet glaciers. Understanding the behavior of these glaciers is therefore key to understanding how much the ice sheet will contribute to sea level in the next century. Glacier behavior is, however, complex, with wide disparities in behavior even between glaciers that occupy adjacent fjords. Deciphering the multitude of factors that control glacier behavior requires a comprehensive dataset of near daily changes in terminus position for a large set of glaciers over many years. The creation of this dataset has been difficult due to the time required to process the changes manually. Evolution in computational methods allows the creation of an automated algorithm, using a combination of filtering techniques and edge detection, which ingests MODIS imagery and tracks changes to (i) the terminus position and (ii) the areal extent of melange downstream of the terminus. We tested the algorithm on several well-studied glaciers including Jakobshavn, Helheim, and Kangerdlugssuaq. Comparison with manually identified terminus positions proved the algorithm accurate to within +/- 2 pixels (500 m). The validated model was then applied to a larger set of Greenland's marine terminating outlet glaciers. We use this higher temporal resolution dataset to determine statistical patterns to the calving events and ask whether these patterns are linked to mélange extent, fjord geometry, and any seasonal component affecting the regularity of the events.
March, Rod S.; O'Neel, Shad
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.
Chad C. Jones; Roger del Moral
Patterns of community development vary among studied glacier forelands around the world. However, there have been few studies of primary succession on glacial forelands in temperate regions of North America. We described patterns in community composition, vegetation cover, diversity, and vegetation heterogeneity during primary succession on the foreland of Coleman Glacier, in Washington State, USA. Community composition changed rapidly with
Stephan Harrison; Neil Glasser; Vanessa Winchester; Eleanor Haresign; Charles Warren; Krister Jansson
Geomorphological mapping, sedimentology, lichenometry and dendrochronology were used to assess the nature and timing of glacier recession, moraine development and catastrophic mass movements in a tributary of the Leones valley, east of the Hielo Patagónico Norte, Chile. We show that during the 'Little Ice Age' Glaciar Calafate advanced downvalley to produce a terminal moraine. Recession of the glacier from this
Quantitative palaeoglaciological studies that use digital surface models (DSMs) may be subject to error because former glacier beds are not always accurately represented. This is because the Earth's surface may have changed significantly since deglaciation. This paper evaluates some of the potential errors caused by postglacial sedimentation, by comparing the results of physical palaeoglaciological reconstructions and bedform morphometric analyses in parts of Scotland, using both the modern land surface and interpolated former glacier beds derived from borehole data. For a former terrestrial outlet glacier, removal of postglacial sediments increases the modelled ice surface elevation and ice thickness by 0.7% and 5%, respectively, over a 27-km flow line. For a former tidewater glacier, the reconstructed steady state ice flux is increased by 250% when the modern land/seabed surface is replaced with an interpolated former glacier bed. In a classical drumlinised landscape, removal of postglacial sediments affects bedform morphometrics, with an increase in measured drumlin length, width, relief, and volume. The cases presented in this paper are from environments known to have experienced postglacial sedimentation. They provide situational examples of the degree of error that can be introduced when the modern land surface is used to represent former glacier beds in these environments. In some regions, sufficient subsurface data exists over large areas to create improved topographic representations of former glacier beds; these could form important inputs to the next generation of palaeo-ice-sheet and palaeo-glacier simulations.
A. Glazovsky; G. Nosenko; O. Rototaeva
State of glaciers on the territory of Russia was documented in the Glacier Inventory of the USSR compiled in 1970s that based on topographic maps and air photo surveys of 1950-1960s. The Inventory covers 20 glaciated areas and is available in paper form and on the NSIDC website. The Inventory contains short text description and basic statistical data about the
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 glaciers being well recognized for their rapid changes and variable flow dynamics, animated sequences of multiple satellite images reveal glacier dynamics in a time-lapse mode, making the otherwise slow changes of glacier movement visible and understandable for a wide public. For this study animated image sequences were created from freely available image quick-looks of orthorectified Landsat scenes for four regions in the central Karakoram mountain range. The animations play automatically in a web-browser and might help to demonstrate glacier flow dynamics for educational purposes. The animations revealed highly complex patterns of glacier flow and surge dynamics over a 15-year time period (1998-2013). In contrast to other regions, surging glaciers in the Karakoram are often small (around 10 km2), steep, debris free, and advance for several years at comparably low annual rates (a few hundred m a-1). The advance periods of individual glaciers are generally out of phase, indicating a limited climatic control on their dynamics. On the other hand, nearly all other glaciers in the region are either stable or slightly advancing, indicating balanced or even positive mass budgets over the past few years to decades.
Recent rapid thinning of the ``Mer de Glace'' glacier derived from satellite optical images E. Comparisons with topographic profiles and a differential DEM from aerial photographs obtained on the Mer de. Baratoux, C. Vincent, and F. Re´my (2004), Recent rapid thinning of the ``Mer de Glace'' glacier derived
E. Berthier; Y. Arnaud; D. Baratoux; C. Vincent; F. Rémy
The rapid wastage of mountain glaciers and their contribution to sea level rise require worldwide monitoring of their mass balance. In this paper, we show that changes in glacier thickness can be accurately measured from satellite images. We use SPOT image pairs to build Digital Elevation Models (DEMs) of the Mont Blanc area (French Alps) for different years. To register
YE, Q.; Moholdt, G.; Gardner, A. S.; Zhang, G.; Zhao, R.; Zhao, Y.; Wouters, B.
We present some observations of glaciers melting and lakes enlargement in typical basins at high latitude on the Tibetan Plateau under the warming climate. Glacier and lake changes in the Mapam Yumco Basin, Yamzhog Yumco and NamCo Basin were studied by series of spatial data from topographic maps, digital satellite images. Using ICESat data, SRTM DEM and local accessible DEMs data, with in-situ measurement of lake level changes, glacier mass changes and glacier melting contributions to lakes were also studied in the above basins. The methodology and its uncertainty would be discussed. The primary results indicate that decreased lakes, retreat glaciers, enlarged lakes and advance glaciers co-exist in the Basins during the last 30 years. Glacier recession was accelerated in recent years due to warmer climate, while both lake reduction and enlargement were accelerated in the corresponding period in some basins. Climate variables (evaporation, precipitation, temperature, etc.) are analyzed to figure out which one is major control factor that drives both glacier and lake mass changes.
Victor M. Levson; Nat W. Rutter
Glaciers flowing down the Athabasca River valley during the last glacial period were fed both by local montane glaciers and by Cordilleran ice moving easterly across the Continental Divide from British Columbia, resulting in a major eastward surge into the ‘ice- free corridor’. The timing of this event has been disputed for many years and has important implications for the
J. S. Kargel; L. Fischer; R. Furfaro; C. Huggel; O. Korup; G. J. Leonard; M. Uhlmann; R. L. Wessels; D. F. Wolfe
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;
Fountain, A.G.; Vecchia, A.
Glacier mass balance is estimated for South Cascade Glacier and Maclure Glacier using a one-dimensional regression of mass balance with altitude as an alternative to the traditional approach of contouring mass balance values. One attractive feature of regression is that it can be applied to sparse data sets where contouring is not possible and can provide an objective error of the resulting estimate. Regression methods yielded mass balance values equivalent to contouring methods. The effect of the number of mass balance measurements on the final value for the glacier showed that sample sizes as small as five stakes provided reasonable estimates, although the error estimates were greater than for larger sample sizes. Different spatial patterns of measurement locations showed no appreciable influence on the final value as long as different surface altitudes were intermittently sampled over the altitude range of the glacier. Two different regression equations were examined, a quadratic, and a piecewise linear spline, and comparison of results showed little sensitivity to the type of equation. These results point to the dominant effect of the gradient of mass balance with altitude of alpine glaciers compared to transverse variations. The number of mass balance measurements required to determine the glacier balance appears to be scale invariant for small glaciers and five to ten stakes are sufficient.
M. Huss; M. Funk; A. Ohmura
A 94-year time series of annual glacier melt at four high elevation sites in the European Alps is used to investigate the effect of global dimming and brightening of solar radiation on glacier mass balance. Snow and ice melt was stronger in the 1940s than in recent years, in spite of significantly higher air temperatures in the present decade. An
ice from warm-based outlet glaciers of Vatnaj ¨okull and O¨ ræfaj ¨okull, Iceland, and analysed them discontinuous layers of sediment-laden ice, forming the stratified fa- cies of the glacier's basal zone Sheets. Roberts et al. (2002) extended supercooling to Skaftafellsj ¨okull, Iceland, and Cook et al
sheets to forecasts of a warming climate and lengthening summer melt season necessitates recogni- tion from temperate valley glaciers. Globally, a significant proportion of glaciers and ice sheets exhibit of supraglacial streams or the propagation of hydrofractures, forms which are readily able to handle varied
...SERVICE, DEPARTMENT OF THE INTERIOR NATIONAL PARK SYSTEM UNITS IN ALASKA Special Regulations-Glacier Bay National Park and Preserve Vessel Permits § 13.1150 Is a permit required for a vessel in Glacier Bay? A permit from the superintendent is...
...SERVICE, DEPARTMENT OF THE INTERIOR NATIONAL PARK SYSTEM UNITS IN ALASKA Special Regulations-Glacier Bay National Park and Preserve Vessel Permits § 13.1150 Is a permit required for a vessel in Glacier Bay? A permit from the superintendent is...
...SERVICE, DEPARTMENT OF THE INTERIOR NATIONAL PARK SYSTEM UNITS IN ALASKA Special Regulations-Glacier Bay National Park and Preserve Vessel Permits § 13.1150 Is a permit required for a vessel in Glacier Bay? A permit from the superintendent is...
Musilova, M.; Tranter, M.; Takeuchi, N.; Anesio, A. M.
Darkened glacier and ice sheet surfaces have lower albedos, absorb more solar radiation and consequently melt more rapidly. The increase in glacier surface darkening is an important positive feedback to warming global temperatures, leading to ever growing world-wide ice mass loss. Most studies focus primarily on glacial albedo darkening caused by the physical properties of snow and ice surfaces, and the deposition of dark impurities on glaciers. To date, however, the important effects of biological activity have not been included in most albedo reduction models. This study provides the first experimental evidence that microbial activity can significantly decrease the albedo of glacier surfaces. An original laboratory experiment, the cryoconite casserole, was designed to test the microbial darkening of glacier surface debris (cryoconite) under simulated Greenlandic summer conditions. It was found that minor fertilisation of the cryoconite (at nutrient concentrations typical of glacial ice melt) stimulated extensive microbial activity. Microbes intensified their organic carbon fixation and even mined phosphorous out of the glacier surface sediment. Furthermore, the microbial organic carbon production, accumulation and transformation caused the glacial debris to darken further by 17.3% reflectivity (albedo analogue). These experiments are consistent with the hypothesis that enhanced fertilisation by anthropogenic inputs results in substantial amounts of organic carbon fixation, debris darkening and ultimately to a considerable decrease in the ice albedo of glacier surfaces on global scales. The sizeable amounts of microbially produced glacier surface organic matter and nutrients can thus be a vital source of bioavailable nutrients for subglacial and downstream environments.
Leithead, W E
From its rebirth in the early 1980s, the rate of development of wind energy has been dramatic. Today, other than hydropower, it is the most important of the renewable sources of power. The UK Government and the EU Commission have adopted targets for renewable energy generation of 10 and 12% of consumption, respectively. Much of this, by necessity, must be met by wind energy. The US Department of Energy has set a goal of 6% of electricity supply from wind energy by 2020. For this potential to be fully realized, several aspects, related to public acceptance, and technical issues, related to the expected increase in penetration on the electricity network and the current drive towards larger wind turbines, need to be resolved. Nevertheless, these challenges will be met and wind energy will, very likely, become increasingly important over the next two decades. An overview of the technology is presented. PMID:17272245
Oberreuter, J.; Gacitúa, G.; Uribe, J.; Rivera, A.; Zamora, R.; Loriaux, T.
Central Chilean glaciers (33-35°S) are an important melt water resource for human consumption, agriculture, mining and industrial activities in this, the most populated region of the country. These glaciers have been retreating and shrinking during recent decades, in response to ongoing climatic changes. As a result, there is increasing concern about future water availability especially during dry summers, when glaciers are thought to have the maximum contribution to runoff. In spite of their importance, very little is known about the total volume of water equivalent storage in these glaciers. In order to improve our knowledge about this issue, we have utilized a new airborne radar system, which was developed at CECs, specially designed to penetrate temperate and cold ice, which is working at central frequencies between 20 and 60 MHz, depending on the penetration range capacity at each glacier. This system has been installed on helicopters, where the metal structure antenna (receptor and transmitter) is carried as a hanging load while flying along pre designated tracks, enabling to survey steep and remote glacier areas, many of them without any ice thickness data up to date. The helicopter is geo-located using dual frequency GPS receivers and an inertial navigation unit installed onboard, and each measurement is geo referenced using a pointing laser located at the radar antenna. The antenna must be flown at 40 m above the glacier surface at an air speed of 40 knots. This system has been successfully used on 24 glaciers representing 16% of the total glacier area of the Aconcagua, Maipo and Rapel basins. A mean ice thickness of 168 m and a maximum of 342 m were detected among the surveyed glaciers. Crossing points between overlapping surveyed tracks resulted in mean differences of near 20 m (less than 10% of the total ice thickness). Subsequent ice volumes were calculated by interpolating radar data collected along tracks. These volumetric estimations correlated well (R=0.85) with area measurements made for each glacier, having a linear regression trend which is similar to the obtained relationships when using global data bases. For example, at the upper Maipo basin (33°S) the Olivares Alfa glacier (area of 4.3 km2 in 2013) has a total volume of water equivalent of 0.17 km3, whilst the Juncal Sur glacier (area of 22.3 km2 in 2013) has a total of 0.65 km3 of water equivalent. A comprehensive and intensive airborne radar program is needed to increase the number of surveyed glaciers, in order to estimate the total volume of water existing in this region.
Josberger, E. G.; Bidlake, W. R.; March, R. S.; Kennedy, B. W.
The mass balance of mid-latitude glaciers of the Pacific Northwest and southern Alaska fluctuates in response to changes in the regional and global atmospheric climate. More than 40 years of net and seasonal mass balance records by the U.S. Geological Survey for South Cascade Glacier, Washington, and Wolverine and Gulkana Glaciers, Alaska, show annual and inter-annual fluctuations that reflect the controlling climatic conditions. South Cascade and Wolverine Glaciers are strongly affected by the warm and wet maritime climate of the Northeast Pacific Ocean, and the winter balances are strongly related to the Pacific Decadal Oscillations (PDO). Gulkana Glacier is more isolated from maritime influences and the net balance variation is more closely linked to the summer balance. By the late 1970's, mass-balance records for the three were long enough to reflect the 1976-77 shift in PDO from negative to positive. Both maritime glaciers responded, with net balance of South Cascade Glacier becoming consistently negative and that of Wolverine Glacier becoming predominantly positive. The overall trend of negative mass balance continued through 2004 for South Cascade Glacier, where the 1977 to 2004 cumulative net balance was about -22 meters water equivalent (mweq). After a gain of about 7 mweq, the trend of positive net balance for Wolverine Glacier ended in 1989. Beginning in 1989, the net balance trend for Wolverine Glacier became predominantly negative and the cumulative net balance for 1989 to 2004 was about -14 mweq. Net balance of Gulkana Glacier did not respond appreciably to the 1976-77 PDO shift. The cumulative net balance for Gulkana Glacier from the beginning of the record (1966) through 1988 was about -3 mweq. The major change in trend of mass balance occurred in 1989, when net balance became almost exclusively negative. The cumulative net balance during 1989 through 2004 was about 13 mweq. As a result trends in net balance had become strongly negative for more than a decade at all three bench mark glaciers.
Carr, Rachel; Stokes, Chris; Vieli, Andreas
Arctic ice masses have rapidly lost mass from the mid-1990s through a combination of negative surface mass balance and accelerated ice discharge from tidewater outlet glaciers. In the past decade, substantial mass deficits have been identified in the Russian High Arctic, predominantly on Novaya Zemlya. However, the factors driving recent changes and the relative contribution of increased glacier discharge to observed mass losses are very poorly understood in this region. Here, we assess the climatic/oceanic and glacier-specific controls on the behaviour of 28 marine-terminating and 10 land-terminating outlet glaciers of the northern ice cap, Novaya Zemlya. We use a combination of ESA SAR Image Mode data and visible imagery to show that >90 % of the study glaciers retreated between 1992 and 2010, at rates of up to 190 m a-1. Mean retreat rates were an order of magnitude greater on marine-terminating outlets (51.2 m a-1) than on their land-terminating counterparts (4.8 m a-1). Moreover, results suggest that the mean retreat rate on marine-terminating glaciers accelerated during the study period, increasing from 22.9 m a-1 (1992-2000) to 88.4 m a-1 (2005-2010), whereas retreat rates on land-terminating glaciers showed little change. We compare marine-terminating outlet glacier frontal position to sea ice concentrations, air temperatures and ocean temperatures, derived from remotely sensed data, and results suggest that sea ice and ocean temperatures are primary controls on frontal position. Mean retreat rates were consistently higher on glaciers terminating in the Barents Sea than in the Kara Sea, potentially due to the longer duration of ice-free conditions and lower sea ice concentrations on the Barents Sea coast. However, the magnitude of marine-terminating outlet glacier retreat varied dramatically between individual glaciers, indicating that glacier-specific factors are a key determinate of glacier response to climatic/oceanic forcing. Specifically, we identify variations in fjord width as a primary control on the pattern and rate of retreat and provide empirical examples of the influence of fjord width on marine-terminating outlet glacier behaviour.
Kargel, J. S.; Fischer, L.; Furfaro, R.; Huggel, C.; Korup, O.; Leonard, G. J.; Uhlmann, M.; Wessels, R. L.; Wolfe, D. F.
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 climate change induced glacier responses in the CRB. Ultimately, climate has the final word, and already this is evident in the glacier record. Glacial flour is probably almost entirely from bed erosion. We will present estimates of the contributions of landslides and subglacially pulverized glacial rock flour to the overall rock mass budget of Allen Glacier. Each of the components of the rock mass budget differs in its probable distribution on the surface and within a typical glacier. We will present some preliminary empirical determinations of the influence of various thicknesses of supraglacial rock debris on the local mass balance of Allen Glacier; the net zero influence is exhibited for debris thicknesses on the order of 1 cm of fine debris or ~50% coverage by cobbles or boulders.
Scambos, T. A.; Bohlander, J. A.; Shuman, C. A.; Skvarca, P.
Ice velocities derived from five Landsat 7 images acquired between January 2000 and February 2003 show a two- to six-fold increase in centerline speed of four glaciers flowing into the now-collapsed section of the Larsen B Ice Shelf. Satellite laser altimetry from ICEsat indicates the surface of Hektoria Glacier lowered by up to 38 +/- 6 m a six-month period beginning one year after the break-up in March 2002. Smaller elevation losses are observed for Crane and Jorum glaciers over a later 5-month period. Two glaciers south of the collapse area, Flask and Leppard, show little change in speed or elevation. Seasonal variations in speed preceding the large post-collapse velocity increases suggest that both summer melt percolation and changes in the stress field due to shelf removal play a major role in glacier dynamics.
Pettit, Erin C.; Lee, Kevin M.; Brann, Joel P.; Nystuen, Jeffrey A.; Wilson, Preston S.; O'Neel, Shad R.
In glacierized fjords, the ice-ocean boundary is a physically and biologically dynamic environment that is sensitive to both glacier 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 non-glacierized fjords). Icy Bay, Alaska has an annual average sound pressure level of 120?dB (re 1 ?Pa) with a broad peak between 1000 and 3000?Hz. Bubble formation in the water column as glacier 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 glacierized fjords. These high noise levels likely alter the behavior of marine mammals.
Glacier Peak in north-central Washington state is not prominently visible from any major metropolitan centers, and so its attractions, as well as its hazards, tend to be overlooked. Yet, Glacier Peak has produced larger and more explosive eruptions than any other Washington volcano except Mount St. Helens. In the past 14,000 years, Glacier Peak has erupted at least a dozen times, most recently around the eighteenth century. The probability and hazards of a future eruption is discussed. Includes map of thickness of ash erupted from Glacier Peak's largest ash eruption about 13,000 years ago and map of areas inundated by debris flows from Glacier Peak eruptions. This is USGS Open-File Report 95-413.
Rowan, A. V.; Egholm, D. L.; Glasser, N. F.; Quincey, D. J.
Recent studies of glaciers in the eastern Himalaya have identified rapid changes in ice volume with small changes in climate indicating that these glaciers are highly sensitive to primary climate variables (e.g. daily variations in air temperature and monsoon precipitation). However, quantifying Himalayan glacier sensitivity to climate change is challenging due to: (1) a lack of information about how glaciological and geomorphological factors influence the balance of large debris-covered glaciers; (2) the local modification of meteorological variables by the interaction of high topography with regional atmospheric circulation systems; and (3) the simple representation of ice dynamics in many numerical glacier models which limits their usefulness in regions with steep terrain. To quantify the sensitivity of Himalayan glaciers to climate change we apply the integrated second-order shallow ice approximation (iSOSIA) [Egholm et al. 2011, Journal of Geophysical Research-Earth Surface] to large debris-covered glaciers on the southern slopes of Mt. Everest in the Khumbu Himal, Nepal. iSOSIA considers both the longitudinal and transverse stresses that drive mountain glacier flow in regions with steep terrain--a more suitable approach for Himalayan glaciers than those models based on approximations developed for shallow ice sheets. We apply iSOSIA at a 100-m resolution on a regular grid using a daily timestep to Nepalese glaciers including Khumbu, Ngozumpa and Lhotse. Our mass balance model development has focused on the dynamic representation of snow avalanching onto the glacier surfaces as this accounts for up to 75% of accumulation. We investigate Himalayan glacier sensitivities to primary climatological, glaciological and geological variables including air temperature, supraglacial debris cover, and catchment hypsometry. Furthermore, we aim to improve the representation of climate in glacier models for the Himalaya by testing a range of methods to describe these variables: (1) simple elevation-dependent rates for accumulation and ablation with empirical values for melt along a flow line beneath supraglacial debris; (2) climate-elevation relationships derived from local automatic weather stations in the Khumbu valley; and (3) 3-D surface energy balance calculations using regional meteorological data. Once we have described glacier-climate sensitivities in the Khumbu Himal, we will use these results to predict the likely magnitude and timescales of glacier mass loss under IPCC future climate change scenarios, and quantify the uncertainties associated with these predictions. Future work will consider: how glacier hydrology modifies variations in ice dynamics; how the spatial distribution of supraglacial debris modifies glacier balance sensitivity; how rock debris is transported within and on these glaciers; and how rates of rock debris delivery from hillslopes affects glacier balance and dynamics. Fieldwork in Nepal is planned for 2014 to collect data from debris-covered Khumbu Glacier with which to validate our numerical model.
The Global Terrestrial Network for Glaciers (GTN-G) is an organizational framework for three operational bodies dedicated to global mapping and monitoring of glacier changes. In this talk I will provide an overview of recent progress made by the World Glacier Monitoring Service (WGMS), the National Snow and Ice Data Center (NSIDC) and the Global Land Ice Measurements from Space (GLIMS) toward distribution and analysis of global in-situ and remotely sensed glacier observations. I will highlight new initiatives aimed at database integration, modernization of internet-based tools, and enhanced community outreach. These activities are helping to generate new discoveries in cryospheric studies, which I will illustrate through several example applications. Finally, I will outline a vision for future GTN-G efforts that will enable rapid response to anticipated glacier variations resulting from climate variability.
Eilar, C. A.; Mikesell, D.; Malcolm, A. E.; Bradford, J. H.
Regular patterns of fractures in solid materials induce seismic velocity anisotropy. These fracture patterns can also create azimuthally dependent attenuation in seismic amplitudes due to a preferential scattering direction. A parallel set of surface (or bed) crevasses in a glacier is an example of one such fracture pattern. These patterns are caused by the local strains within the glacier. In this study we analyze an active source 3D seismic survey recorded at Bench Glacier, Alaska, USA. We compare the Rayleigh group wave velocity as a function of azimuth and estimate that the mean velocity is 1672 m/s and 1% velocity anisotropy exists. We present an interpretation for the observed anisotropy by comparing our results with satellite imagery of the glacier in the survey area. Finally, we present the results of ongoing analysis of the Rayleigh wave amplitudes and compare with existing studies of glacier attenuation that do not take into account scattering attenuation when estimating the ice temperature from attenuation.
Oneel, S.; Hood, E. W.; Arendt, A. A.; Sass, L. C.; March, R. S.
The timing and magnitude of freshwater discharge to the Gulf of Alaska impacts rates of sea level change and the health of near shore ecosystems and fisheries. Glaciers strongly modulate the freshwater flux into this region and contribute to approximately 50% of its annual freshwater budget. It is generally assumed that persistently negative annual mass balances, forced by recent climate changes, are driving increases in glacier stream discharge. However, increases in runoff also depend on increased mass turnover rates, wherein the amplitude of seasonal mass balance increases due to enhanced snowfall and summer melt intensity. To quantify and partition runoff into the Gulf of Alaska we examine 1966-2010 US Geological Survey glacier mass balance and streamflow records from the Gulkana/Wolverine glaciers located in continental/maritime Alaska climate regimes. We compare annual, summer and winter balances with associated discharge magnitudes at each glacier to determine the primary controls on runoff magnitude and timing. We find that both glaciers have experienced increases in runoff and mass turnover, but only the Gulkana Glacier shows increases in stream discharge due to long term changes in annual mass balance. Conversely, Wolverine Glacier runoff is more sensitive to the amplitude of winter accumulation. The data suggest that changes in summer climate forcing are occurring over broader spatial scales than are changes in winter forcing. The analyses demonstrate that care is warranted when formulating assumptions relating glacier volume change to surface water hydrologic processes. Predicting future changes in runoff and implications for sea level rise, water resources and biological resources in this highly productive region requires that we better understand the processes that produce and modulate glacier runoff.
Carr, R.; Stokes, C.; Vieli, A.
Arctic ice masses have lost mass rapidly during the past two decades and accelerated discharge through marine-terminating outlet glaciers has been a primary component of deficits from the Greenland Ice Sheet. However, previous studies have focused on individual glaciers or regions, meaning that little is known about broad-scale trends in outlet glacier retreat rates, their spatial variation across the Arctic and/or their differing response to forcing. Here we present the first pan-Atlantic-Arctic assessment of outlet glacier retreat rates and their relationship to forcing factors. During the past two decades (1992-2010) we demonstrate an almost ubiquitous trend of rapid and accelerating outlet glacier retreat trend across the Atlantic Arctic. Between 1992 and 2000, 77 % of our 321 study glaciers retreated, compared to 95 % between 2000 a