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1

Utility of late summer transient snowline migration rate on Taku Glacier, Alaska  

NASA Astrophysics Data System (ADS)

On Taku Glacier, Alaska a combination of field observations of snow water equivalent (SWE) from snowpits and probing in the vicinity of the transient snowline (TSL) are used to quantify the mass balance gradient. The balance gradient derived from the TSL and SWE measured in snowpits at 1000 m from 1998-2010 ranges from 2.6-3.8 mm m-1. Probing transects from 950 m-1100 m directly measure SWE and yield a slightly higher balance gradient of 3.3-3.8 mm m-1. The TSL on Taku Glacier is identified in MODIS and Landsat 4 and 7 Thematic Mapper images for 31 dates during the 2004-2010 period to assess the consistency of its rate of rise and reliability in assessing ablation for mass balance assessment. For example, in 2010, the TSL was 750 m on 28 July, 800 m on 5 August, 875 m on 14 August, 925 m on 30 August, and 975 m on 20 September. The mean observed probing balance gradient was 3.3 mm m-1, combined with the TSL rise of 3.7 m day-1 yields an ablation rate of 12.2 mm day-1 from mid-July to mid-Sept, 2010. The TSL rise in the region from 750-1100 m on Taku Glacier during eleven periods each covering more than 14 days during the ablation season indicates a mean TSL rise of 3.7 m day-1, the rate of rise is relatively consistent ranging from 3.1 to 4.4 m day-1. This rate is useful for ascertaining the final ELA if images or observations are not available near the end of the ablation season. The mean ablation from 750-1100 m during the July-September period determined from the TSL rise and the observed balance gradient is 11-13 mm day-1 on Taku Glacier during the 2004-2010 period. The potential for providing an estimate of bn from TSL observations late in the melt season from satellite images combined with the frequent availability of such images provides a means for efficient mass balance assessment in many years and on many glaciers.

Pelto, M.

2011-12-01

2

Mendenhall Glacier Juneau, Alaska  

E-print Network

· · · · · · #12;V1 Mendenhall Glacier Juneau, Alaska 404 Alaskan Frontiers & Glaciers V1 PRSRTSTD U blend of nature and modern culture. Marvel at the spectacular Hubbard Glacier, the longest tidewater glacier in Alaska and visit Icy Strait Point, a seaport nestled in the lush, seemingly endless northern

Raina, Ramesh

3

Alaska Glaciers and Rivers  

NASA Technical Reports Server (NTRS)

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this image on October 7, 2007, showing the Alaska Mountains of south-central Alaska already coated with snow. Purple shadows hang in the lee of the peaks, giving the snow-clad land a crumpled appearance. White gives way to brown on the right side of the image where the mountains yield to the lower-elevation Susitna River Valley. The river itself cuts a silver, winding path through deep green forests and brown wetlands and tundra. Extending from the river valley, are smaller rivers that originated in the Alaska Mountains. The source of these rivers is evident in the image. Smooth white tongues of ice extend into the river valleys, the remnants of the glaciers that carved the valleys into the land. Most of the water flowing into the Gulf of Alaska from the Susitna River comes from these mountain glaciers. Glacier melt also feeds glacier lakes, only one of which is large enough to be visible in this image. Immediately left of the Kahiltna River, the aquamarine waters of Chelatna Lake stand out starkly against the brown and white landscape.

2007-01-01

4

Malaspina Glacier, Alaska  

NASA Technical Reports Server (NTRS)

This image from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra satellite covers an area of 55 by 40 kilometers (34 by 25 miles) over the southwest part of the Malaspina Glacier and Icy Bay in Alaska. The composite of infrared and visible bands results in the snow and ice appearing light blue, dense vegetation is yellow-orange and green, and less vegetated, gravelly areas are in orange. According to Dr. Dennis Trabant (U.S. Geological Survey, Fairbanks, Alaska), the Malaspina Glacier is thinning. Its terminal moraine protects it from contact with the open ocean; without the moraine, or if sea level rises sufficiently to reconnect the glacier with the ocean, the glacier would start calving and retreat significantly. ASTER data are being used to help monitor the size and movement of some 15,000 tidal and piedmont glaciers in Alaska. Evidence derived from ASTER and many other satellite and ground-based measurements suggests that only a few dozen Alaskan glaciers are advancing. The overwhelming majority of them are retreating.

This ASTER image was acquired on June 8, 2001. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next six years to map and monitor the changing surface of our planet.

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 Economy, 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; Bjorn Eng of JPL is the project manager. ASTER is the only high-resolution imaging sensor on Terra. The Terra mission is part of NASA's Earth Science Enterprise, along-term research and technology program designed to examine Earth's land, oceans, atmosphere, ice and life as a total integrated system.

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.

Size: 55 by 40 kilometers (34 by 25 miles) Location: 60.0 degrees North latitude, 140.7 degrees West longitude Orientation: North at top Image Data: ASTER bands 2, 3 and 4 Original Data Resolution: 15 meters (49 feet) Date Acquired: June 8, 2001

2001-01-01

5

Lack of trophic competition among wild and hatchery juvenile chum salmon during early marine residence in Taku Inlet, Southeast Alaska  

Microsoft Academic Search

Early marine trophic interactions of wild and hatchery chum salmon (Oncorhynchus keta) were examined as a potential cause for the decline in harvests of adult wild chum salmon in Taku Inlet, Southeast Alaska.\\u000a In 2004 and 2005, outmigrating juvenile chum salmon were sampled in nearshore habitats of the inlet (spring) and in epipelagic\\u000a habitat at Icy Strait (summer) as they

Molly V. Sturdevant; Emily Fergusson; Nicola Hillgruber; Carl Reese; Joe Orsi; Rick Focht; Alex Wertheimer; Bill Smoker

6

Regional Observations of Alaska Glacier Dynamics  

NASA Astrophysics Data System (ADS)

Alaska glaciers contribute more to sea level rise than any other glacierized mountain region in the world. Alaska is loosing ~84 Gt of ice annually, which accounts for ~0.23 mm/yr of SLR (Luthcke et al., 2008). Complex glacier flow dynamics, frequently related to tidewater environments, is the primary cause of such rapid mass loss (Larsen et al., 2007). Indirect observations indicate these complex flow dynamics occur on many glaciers throughout Alaska, but no comprehensive velocity measurements exist. We are working to measure glacier surface velocities throughout Alaska using synthetic aperture radar (SAR) offset tracking. This work focuses on the Seward/Malaspina, Bering, Columbia, Kaskawulsh, and Hubbard Glaciers and uses a MODIS land surface temperature "melt-day" product (Hall et al., 2006, 2008) to identify potential links between velocity variability and summertime temperature fluctuations. Hall, D., R. Williams Jr., K. Casey, N. DiGirolamo, and Z. Wan (2006), Satellite-derived, melt-season surface temperature of the Greenland Ice Sheet (2000-2005) and its relationship to mass balance, Geophysical Research Letters, 33(11). Hall, D., J. Box, K. Casey, S. Hook, C. Shuman, and K. Steffen (2008), Comparison of satellite-derived and in-situ observations of ice and snow surface temperatures over Greenland, Remote Sensing of Environment, 112(10), 3739-3749. Larsen, C. F., R. J. Motyka, A. A. Arendt, K. A. Echelmeyer, and P. E. Geissler (2007), Glacier changes in southeast Alaska and northwest British Columbia and contribution to sea level rise, J. Geophys. Res. Luthcke, S., A. Arendt, D. Rowlands, J. McCarthy, and C. Larsen (2008), Recent glacier mass changes in the Gulf of Alaska region from GRACE mascon solutions, Journal of Glaciology, 54(188), 767-777.

Burgess, E. W.; Forster, R. R.; Hall, D. K.

2010-12-01

7

Analysis of time series of glacier speed: Columbia Glacier, Alaska  

USGS Publications Warehouse

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

Walters, R.A.; Dunlap, W.W.

1987-01-01

8

Columbia Glacier, Alaska, 1986-2011 - Duration: 0:29.  

NASA Video Gallery

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 ...

9

Rapid Thinning of a Lake Calving Glacier: Yakutat Glacier, Southeast Alaska  

Microsoft Academic Search

Calving glaciers around the world have recently undergone a rapid retreat and are important contributors to global sea level rise. Due to their greatly increased mass loss, tidewater glaciers in particular have long received much attention, whereas lake calving glaciers have just been identified as significant contributors. In southeast Alaska, numerous glaciers have experienced rapid retreat and significant thinning during

B. Truessel; R. J. Motyka; C. F. Larsen; M. Truffer

2010-01-01

10

The altitudinal distribution of snow algae on an Alaska glacier (Gulkana Glacier in the Alaska Range)  

NASA Astrophysics Data System (ADS)

The altitudinal distribution of a snow algal community was investigated on an Alaska glacier (Gulkana Glacier in the Alaska Range) from 1270 to 1770 m a.s.l.. Seven species of snow and ice algae (Chlorophyta and cyanobacteria) were observed on the glacier surface. These species were Chlamydomonas nivalis, Mesotaenium berggrenii, Ancylonema nordenskioldii, Cylindrocystis brbissonii, Raphidonema sp., and two Oscillatoriaceae cyanobacteria. The altitudinal distribution of snow algae was different among the species: Cd. nivalis was distributed on the middle to upper area, M. berggrenii; A. nordenskioldii, and one Oscillatoriaceae cyanobacterium on the middle to lower area; Raphidonema sp. on the middle area; and Cyl. brbissonii and one Oscillatoriaceae cyanobacterium on the lower area. The total cell concentration and the cell volume biomass of the snow algae ranged from 44 103 to 99 105 cells ml-1 and from 33 to 2211 l m-2 respectively. The cell volume biomass changed with altitude; the biomass increased with altitude below 1600 m a.s.l., and decreased above 1600 m a.s.l. The community structure showed that glacier, and that glacier. The altitudinal distribution of snow algae is discussed in terms of the physical and chemical condition of the glacier surface, and is compared with that on a Himalayan glacier. A larger biomass in the snow area on the Alaska glacier than that of the Himalayan glacier is likely due to less frequent snow cover in summer in Alaska. Small amounts of filamentous cyanobacteria on the Alaska glacier may allow washouts of unicellular green algae by running melt water and may cause a different pattern of altitudinal distribution of algal biomass on the ice area from the Himalayan glacier.

Takeuchi, Nozomu

2001-12-01

11

Alaska PaleoGlacier Atlas: A Geospatial Compilation of Pleistocene Glacier Extents  

NSDL National Science Digital Library

The Alaska PaleoGlacier (APG) Atlas is a recently released, web-based summary of Pleistocene glaciation across Alaska. Students can access a gallery of maps depicting the extent of glaciers during the late Wisconsin glaciation in Alaska as well as the maximum extent reached during the last 3 million years by valley glaciers, ice caps, and the northwestern Cordilleran Ice Sheet. a set of links is also provided to sites on galcial geology and glacial geospatial data.

William Manley

12

Malaspina Glacier, Alaska, Perspective with Landsat Overlay  

NASA Technical Reports Server (NTRS)

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

This perspective view was created from a Landsat satellite image and an elevation model generated by the Shuttle Radar Topography Mission (SRTM). Landsat views both visible and infrared light, which have been combined here into a color composite that generally shows glacial ice in light blue, snow in white, vegetation in green, bare rock in grays and tans, and the ocean (foreground) in dark blue. The back (northern) edge of the data set forms a false horizon that meets a false sky.

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.

Glaciers are sensitive indicators of climatic change. They can grow and thicken with increasing snowfall and/or decreased melting. Conversely, they can retreat and thin if snowfall decreases and/or atmospheric temperatures rise and cause increased melting. Landsat imaging has been an excellent tool for mapping the changing geographic extent of glaciers since 1972. The elevation measurements taken by SRTM in February 2000 now provide a near-global baseline against which future non-polar region glacial thinning or thickening can be assessed.

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 kilometers wide x 55 kilometers distance (34 x 34 miles) Location: 60 deg N latitude, 140 deg W longitude Orientation: View North, 2X vertical exaggeration Image Data: Landsat Thematic Mapper false-color image Original Data Resolution: SRTM 1 arcsecond (30 meters or 98 feet), Landsat 30 meters (98 feet) Date Acquired: February 2000 (SRTM), 31 August 2000 (Landsat)

2003-01-01

13

Widespread Alaska glacier retreat likely not due to climate change  

NASA Astrophysics Data System (ADS)

Alaska's Columbia Glacier, which has shed half its mass since 1957, is a dramatic example of how quickly glaciers can shrink. Yet while Columbia has shown a huge decline, a new analysis by McNabb and Hock has found that other glaciers in the region have retreated far less, or even advanced, over the past 6 decades.

Schultz, Colin

2014-06-01

14

Columbia Glacier, Alaska: changes in velocity 1977-1986  

USGS Publications Warehouse

The Columbia Glacier, a grounded, iceberg-calving tidewater glacier near Valdez, Alaska, began to retreat about 1977. Drastic retreat occurred in 1984, and by early 1986, retreat amounted to 2km. The glacier has thinned more than 100m since 1974 at a point 4km behind the 1974 terminus position. Between 1977 and 1985 the lower glacier ice velocity increased from 3-8m/d to 10-15m/d. -from Authors

Krimmel, R.M.; Vaughn, B.H.

1987-01-01

15

Glacier Bay, Alaska, from the Ground, Air and Space  

NSDL National Science Digital Library

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.

Cindy Starr

1996-02-23

16

Dendrochronology and Late Holocene History of Bering Piedmont Glacier, Alaska  

Microsoft Academic Search

Fluctuations of the piedmont lobe of Bering Glacier and its sublobe Steller Glacier over the past two millennia are reconstructed using 34 radiocarbon dates and tree-ring data from 16 sites across the glaciers' forelands. The general sequence of glacial activity is consistent with well-dated fluctuations of tidewater and land-terminating glaciers elsewhere along the Gulf of Alaska. Extensive forested areas along

Gregory C. Wiles; Austin Post; Ernest H. Muller; Bruce F. Molnia

1999-01-01

17

Malaspina Glacier, Alaska, Anaglyph with Landsat Overlay  

NASA Technical Reports Server (NTRS)

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

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

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

2003-01-01

18

Glaciers along proposed routes extending the Copper River Highway, Alaska  

USGS Publications Warehouse

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

Glass, R.L.

1996-01-01

19

Drainage events from a glacier-dammed lake, Bear Glacier, Alaska: Remote sensing and field observations  

NASA Astrophysics Data System (ADS)

We investigated drainage events from a glacier-dammed lake on Bear Glacier, Alaska, and associated outburst floods and hazards. The glacier-dammed lake, which we call Ice Lake, is 17.5 km up-glacier from Bear Glacier's terminus at Bear Glacier Lake. We combine field observations and remote sensing to examine temporal changes in the size of Ice Lake, the frequency and timing of its drainage, and down-glacier propagation of its outburst floods. We found that in recent years, Ice Lake has likely drained every year or two, in late summer or fall (August-October), with outbursts generally following the damming of sufficient water to create a lake area of between 0.35 and 0.5 km2. Ice Lake has migrated downvalley to the south since the 1990s, likely as a result of thinning of the glacier that dams it. In situ measurements of a drainage event in October 2010 showed that Ice Lake drained over a period of days, which manifested at Bear Glacier Lake as a gradual, multiday increase and then decrease in water levels. Glacial lake outburst flooding at Bear Glacier creates risks for sea kayakers in Bear Glacier Lake and may be relevant to understanding the effects of climate warming on glacier-dammed and proglacial lakes.

Wilcox, A. C.; Wade, A. A.; Evans, E. G.

2014-09-01

20

GLACIER DAMMED LAKES AND OUTBURST FLOODS IN ALASKA  

Microsoft Academic Search

h 4 INTRODUcrION Glaciers in Alaska cover an area of about 73,800 square kilometers (28,500 square miles). They are most highly concentrated along the Pacific Coast and in the south-central part of the State. Many of these g1aciers;as elsewhere in the world, flow across the mouths of adjoining valleys and cause lakes to form behind the ice streams. These glacier

Austin Post; Lawrence R. Mayo; ATLAS HA

1971-01-01

21

foreland strata, Bering Glacier, Alaska. Geomorphology 75, 12, 201211.  

E-print Network

foreland strata, Bering Glacier, Alaska. Geomorphology 75, 12, 201211. Fritts, H. C. (1976). Tree. (2003). Tree ring analyses and detailed geomorphological mapping on a forested debris flow cone 31(2), 243248. Luckman, B. H. (2000). The Little Ice Age in the Canadian Rockies. Geomorphology 32

Smith, Dan

22

Rapid Thinning of a Lake Calving Glacier: Yakutat Glacier, Southeast Alaska  

NASA Astrophysics Data System (ADS)

Calving glaciers around the world have recently undergone a rapid retreat and are important contributors to global sea level rise. Due to their greatly increased mass loss, tidewater glaciers in particular have long received much attention, whereas lake calving glaciers have just been identified as significant contributors. In southeast Alaska, numerous glaciers have experienced rapid retreat and significant thinning during the last several decades. To better understand the causes for these rapid changes we have focused on Yakutat Glacier, a lake calving glacier in southeast Alaska. Yakutat Glacier is part of the Yakutat Ice field and drains into Harlequin Lake, which has depths of over 300 m at the calving face. The ice field covers an area of 668 sq km and lies in a maritime area off the coast of the Gulf of Alaska. The average precipitation in the nearby town of Yakutat is over 3800 mm per year. However, the ice field divide is essentially at or below the current equilibrium line altitude (ELA) of 800 - 900 m for this region, thereby ensuring the glacier will continue to thin, provided the current trend of regional warming does not reverse. The ongoing thinning continues to lower the glaciers average elevation, increasing its average ablation, even under constant climate. This forms a positive feedback loop that is known as the Bovardsson effect. In addition, radio echo sounding shows much of the glacier base near or below sea level, indicating that lake calving will remain playing a role in the retreat. We obtained a 40 m-grid digital elevation model (DEM) derived from September 3, 2007 SPOT imagery and obtained under the IPY SPIRIT program. We used August 26, 2007 laser altimetry profiles to check the accuracy of the DEM and found a mean difference of 2 m (DEM greater) with a standard deviation of 2.3 m. We differenced this DEM from a DEM from the February 2000 Shuttle Radar Topography Mission to determine the extent of the volume change and thinning. During this period, the Yakutat Ice field lost about 22.4 7.5 cubic km of ice, with thinning rates increasing down glacier, especially towards the glacier's grounding line. Just up glacier from this grounding line, we found elevation changes of over 10 m per year. The same trend is visible in a comparison between the 2007 Spot DEM and a July 2009 DEM generated from photogrammetry imagery. Little change in surface elevation occurred over the 2-km-long floating tongue during this time period, but recently the entire floating tongue has started to disintegrate.

Truessel, B.; Motyka, R. J.; Larsen, C. F.; Truffer, M.

2010-12-01

23

Variations in Alaska tidewater glacier frontal ablation, 1985-2013  

NASA Astrophysics Data System (ADS)

Our incomplete knowledge of the proportion of mass loss due to frontal ablation (the sum of ice loss through calving and submarine melt) from tidewater glaciers outside of the Greenland and Antarctic ice sheets has been cited as a major hindrance to accurate predictions of global sea level rise. We present a 28 year record (1985-2013) of frontal ablation for 27 Alaska tidewater glaciers (representing 96% of the total tidewater glacier area in the region), calculated from satellite-derived ice velocities and modeled estimates of glacier ice thickness. We account for cross-sectional ice thickness variation, long-term thickness changes, mass lost between an upstream fluxgate and the terminus, and mass change due to changes in terminus position. The total mean rate of frontal ablation for these 27 glaciers over the period 1985-2013 is 15.11 3.63Gta-1. Two glaciers, Hubbard and Columbia, account for approximately 50% of these losses. The regional total ablation has decreased at a rate of 0.14Gta-1 over this time period, likely due to the slowing and thinning of many of the glaciers in the study area. Frontal ablation constitutes only 4% of the total annual regional ablation, but roughly 20% of net mass loss. Comparing several commonly used approximations in the calculation of frontal ablation, we find that neglecting cross-sectional thickness variations severely underestimates frontal ablation.

McNabb, R. W.; Hock, R.; Huss, M.

2015-01-01

24

The Effects of Changing Climate on Glaciers in the Central Alaska Range, Alaska, USA: A Case Study on the Kahiltna Glacier  

Microsoft Academic Search

This study will develop a set of modeling tools to provide estimates of melt evolution for the Kahiltna Glacier and glaciers of the Central Alaska Range (CAKR), over a number of future climate change scenarios. To parameterize the model, field measurements of mass balance and meteorological variables are being collected on the Kahiltna Glacier. These measurements include winter accumulation surveys

J. C. Young; A. A. Arendt

2010-01-01

25

The slow advance of a calving glacier: Hubbard Glacier, Alaska, U.S.A  

USGS Publications Warehouse

Hubbard Glacier is the largest tidewater glacier in North America. In contrast to most glaciers in Alaska and northwestern Canada, Hubbard Glacier thickened and advanced during the 20th century. This atypical behavior is an important example of how insensitive to climate a glacier can become during parts of the calving glacier cycle. As this glacier continues to advance, it will close the seaward entrance to 50 km long Russell Fjord and create a glacier-dammed, brackish-water lake. This paper describes measured changes in ice thickness, ice speed, terminus advance and fjord bathymetry of Hubbard Glacier, as determined from airborne laser altimetry, aerial photogrammetry, satellite imagery and bathymetric measurements. The data show that the lower regions of the glacier have thickened by as much as 83 m in the last 41 years, while the entire glacier increased in volume by 14.1 km3. Ice speeds are generally decreasing near the calving face from a high of 16.5 m d-1 in 1948 to 11.5 m d-1 in 2001. The calving terminus advanced at an average rate of about 16 m a-1 between 1895 and 1948 and accelerated to 32 m a-1 since 1948. However, since 1986, the advance of the part of the terminus in Disenchantment Bay has slowed to 28 m a-1. Bathymetric data from the lee slope of the submarine terminal moraine show that between 1978 and 1999 the moraine advanced at an average rate of 32 m a-1, which is the same as that of the calving face.

Trabant, D.C.; Krimmel, R.M.; Echelmeyer, K.A.; Zirnheld, S.L.; Elsberg, D.H.

2003-01-01

26

Southern Alaska Glaciers: Spatial and Temporal Variations in Ice Volume  

NASA Technical Reports Server (NTRS)

Although temperate mountain glaciers comprise less than 1% of the glacier-covered area on Earth, they are important because they appear to be melting rapidly under present climatic conditions and, therefore, make significant contributions to rising sea level. In this study, we use ICESat observations made in the last 1.5 years of southern Alaska glaciers to estimate ice elevation profiles, ice surface slopes and roughness, and bi-annual and/or annual ice elevation changes. We report initial results from the near coastal region between Yakutat Bay and Cape Suckling that includes the Malaspina and Bering Glaciers. We show and interpret ice elevations changes across the lower reaches of the Bagley Ice Valley for the period between October 2003 and May 2004. In addition, we use off-nadir pointing observations to reference tracks over the Bering and Malaspina Glaciers in order to estimate annual ice elevation change. Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Shuttle Radar Topography Mission (SRTM) derived DEMs are used to estimate across track regional slopes between ICESat data acquisitions. Although the distribution and quantity of ICESat elevation profiles with multiple, exact repeat data is currently limited in Alaska, individual ICESat data tracks, provide an accurate reference surface for comparison to other elevation data (e.g. ASTER and SRTM X- and C-band derived DEMs). Specifically we report the elevation change over the Malaspina Glacier's piedmont lobe between a DEM derived from SRTM C-band data acquired in Feb. 2000 and ICESat Laser #2b data from Feb.-March 2004. We also report use of ICESat elevation data to enhance ASTER derived absolute DEMs. Mountain glaciers generally have rougher surfaces and steeper regional slopes than the ice sheets for which the ICESat design was optimized. Therefore, rather than averaging ICESat observations over large regions or relying on crossovers, we are working with well-located ICESat footprint returns to estimate glacier ice elevations and surface characteristics. Additional information is included in the original extended abstract.

Sauber, J.; Molnia, B. F.; Lutchke, S.; Rowlands, D.; Harding, D.; Carabajal, C.; Hurtado, J. M.; Spade, G.

2004-01-01

27

A new inventory of glaciers and supraglacial debris for the Alaska Range with a case study of rock avalanche loading  

Microsoft Academic Search

Glacier area is in constant fluctuation and, to date, the only available inventory of glaciers within the Alaska Range was compiled from imagery acquired in 1948 to 1956 by the US Geological Survey. This study presents a new comprehensive inventory of Alaska Range glaciers that was digitized manually from Landsat and ASTER satellite images spanning 2004 to 2010. Glacier flow

S. J. Herreid; A. A. Arendt; R. M. Hock; C. Kienholz

2010-01-01

28

Application of Near-Surface Geophysics to Problems in Glacier Dynamics, Pitted Outwash Plain Formation, and Glaciotectonics, Matanuska Glacier, Alaska  

Microsoft Academic Search

From 2000 to 2004, near-surface geophysics data in various forms was collected near the active terminus of Matanuska Glacier, Alaska, to address several specific hypotheses and also provide general subsurface information in several relatively unsampled zones of the subsurface. (1) Seismic reflection data was collected on the glacier to test the predicted thickening of debris-rich basal ice in response to

G. S. Baker; K. Pyke; E. Evenson; D. Lawson; G. Larson; R. B. Alley

2005-01-01

29

Growth of a post-Little Ice Age submarine fan, Glacier Bay, Alaska  

USGS Publications Warehouse

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.

Carlson, P.R.; Cowan, E.A.; Powell, R.D.; Cai, J.

1999-01-01

30

Rapid Wastage of Alaska Glaciers and Their Contribution to Rising Sea Level  

Microsoft Academic Search

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

Anthony A. Arendt; Keith A. Echelmeyer; William D. Harrison; Craig S. Lingle; Virginia B. Valentine

2002-01-01

31

Dendrochronology and late Holocene history of Bering piedmont glacier, Alaska  

USGS Publications Warehouse

Fluctuations of the piedmont lobe of Bering Glacier and its sublobe Steller Glacier over the past two millennia are reconstructed using 34 radiocarbon dates and tree-ring data from 16 sites across the glaciers' forelands. The general sequence of glacial activity is consistent with well-dated fluctuations of tidewater and land-terminating glaciers elsewhere along the Gulf of Alaska. Extensive forested areas along 25 km of the Bering ice margin were inundated by glacio-lacustrine and glacio-fluvial sediments during a probable ice advance shortly before 500 cal yr A.D. Regrowth of forests followed the retreating ice as early as the 7th century A.D., with frequent interruptions of tree growth due to outwash aggradation. Forests overrun by ice and buried in outwash indicate readvance about 1080 cal yr A.D. Retreat followed, with ice-free conditions maintained along the distal portions of the forefield until the early 17th century after which the ice advanced to within a few kilometers of its outer Neoglacial moraine. Ice reached this position after the mid-17th century and prior to 200 yr ago. Since the early 20th century, glacial retreat has been punctuated by periodic surges. The record from forests overrun by the nonsurging Steller Lobe shows that this western ice margin was advancing by 1250 A.D., reaching near its outer moraine after 1420 cal yr A.D. Since the late 19th century, the lobe has dominantly retreated.

Wiles, G.C.; Post, A.; Muller, E.H.; Molnia, B.F.

1999-01-01

32

High porosity of basal till at Burroughs glacier, southeastern Alaska  

SciTech Connect

Debris-rich basal ice at Burroughs glacier, southeastern Alaska, has 60 vol% to 70 vol% debris. Recently deposited basal till exceeds 60 vol% sediment with 30% to almost 40% porosity. Where basal ice is very rich in debris, basal till is deposited through melt out with only slight compaction of the debris. Porosity this high in till is commonly associated with subglacially deforming and dilated sediment. However, the recently deposited basal melt-out till at Burroughs glacier has not been deformed after deposition, but has porosity values similar to tills elsewhere interpreted to be subglacially deforming and dilated in an unfrozen state. High porosity can occur in basal melt-out till deposited directly by basal melt out.

Ronnert, L.; Mickelson, D.M. (Univ. of Wisconsin, Madison (United States))

1992-09-01

33

Exploring tidewater glacier retreat using past and current observations at Columbia Glacier, Alaska. (Invited)  

NASA Astrophysics Data System (ADS)

Since fulfilling Austin Posts 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).

O'Neel, S.; Pfeffer, W. T.; Howat, I. M.; Conway, H.; Columbia Glacier Consortium

2010-12-01

34

Accurate ocean tide modeling in southeast Alaska and large tidal dissipation around Glacier Bay  

Microsoft Academic Search

An accurate prediction of ocean tides in southeast Alaska is developed using a regional, barotropic ocean model with a finite\\u000a difference scheme. The model skill is verified by the observational tidal harmonics in southeast Alaska including Glacier\\u000a Bay. The result is particularly improved in Glacier Bay compared to the previous model described by Foreman et al. (2000). The model bathymetry

Daisuke Inazu; Tadahiro Sato; Satoshi Miura; Yusaku Ohta; Kazuyuki Nakamura; Hiromi Fujimoto; Christopher F. Larsen; Tomoyuki Higuchi

2009-01-01

35

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

Microsoft Academic Search

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;

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

2009-01-01

36

Multitemporal Landsat multispectral scanner and thematic mapper data of the Hubbard Glacier region, southeast Alaska  

USGS Publications Warehouse

In late May 1986, the advancing Hubbard Glacier blocked the entrance to Russell Fiord near Yakutat, Alaska, creating a large ice-dammed lake. Runoff from the surrounding glaciated mountains raised the level of the lake to about 25 m above sea level by 8 October, when the ice dam failed. Remote sensing offers one method to monitor this large tidal glacier system, particularly the glacier activity that would portend the re-closure of Russell Fiord. -Authors

Walker, K.-M.; Zenone, C.

1988-01-01

37

Muir and Riggs Glaciers, Muir Inlet, Alaska - 1941  

USGS Multimedia Gallery

This northeast-looking photograph, on the southeastern side of White Thunder Ridge ,shows the lower reaches of Muir Glacier, then a large tidewater calving valley glacier, and its tributary Riggs Glacier. The sracs in the lower right-hand corner of the photograph mark Muir Glaciers te...

38

Exploring the links between transient water inputs and glacier velocity in a small temperate glacier in southeastern Alaska  

NASA Astrophysics Data System (ADS)

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.

Heavner, M.; Habermann, M.; Hood, E. W.; Fatland, D. R.

2009-12-01

39

Exploring the links between transient water inputs and glacier velocity in a small temperate glacier in southeastern Alaska  

NASA Astrophysics Data System (ADS)

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.

Habermann, M.; Hood, E.; Heavner, M.; Motyka, R.

2008-12-01

40

Combined Ice and Water Balances of Maclure Glacier, California, South Cascade Glacier, Washington, and Wolverine and Gulkana Glaciers, Alaska, 1967 Hydrologic Year  

USGS Publications Warehouse

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.

Tangborn, Wendell V.; Mayo, Lawrence R.; Scully, David R.; Krimmel, Robert M.

1977-01-01

41

Debris Supply as a Control on the Development of Rock Glaciers in the Central Brooks Range, Alaska  

Microsoft Academic Search

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

A. Ikeda; K. Yoshikawa

2009-01-01

42

Analysis of a GRACE global mascon solution for Gulf of Alaska glaciers  

USGS Publications Warehouse

We present a high-resolution Gravity Recovery and Climate Experiment (GRACE) mascon solution for Gulf of Alaska (GOA) glaciers and compare this with in situ glaciological, climate and other remote-sensing observations. Our GRACE solution yields a GOA glacier mass balance of 65 11 Gt a1 for the period December 2003 to December 2010, with summer balances driving the interannual variability. Between October/November 2003 and October 2009 we obtain a mass balance of 61 11 Gt a1 from GRACE, which compares well with 65 12 Gt a1 from ICESat based on hypsometric extrapolation of glacier elevation changes. We find that mean summer (JuneAugust) air temperatures derived from both ground and lower-troposphere temperature records were good predictors of GRACE-derived summer mass balances, capturing 59% and 72% of the summer balance variability respectively. Large mass losses during 2009 were likely due to low early melt season surface albedos, measured by the Moderate Resolution Imaging Spectroradiometer (MODIS) and likely associated with the 31 March 2009 eruption of Mount Redoubt, southwestern Alaska. GRACE data compared well with in situ measurements at Wolverine Glacier (maritime Alaska), but poorly with those at Gulkana Glacier (interior Alaska). We conclude that, although GOA mass estimates from GRACE are robust over the entire domain, further constraints on subregional and seasonal estimates are necessary to improve fidelity to ground observations.

Arendt, Anthony; Luthcke, Scott; Gardner, Alex; O'Neel, Shad; Hill, David; Moholdt, Geir; Abdalati, Waleed

2013-01-01

43

Alaska Park Science, Volume 12, Issue 2 Status and Trends of Alaska National Park Glaciers  

E-print Network

Glaciers: What Do They Tell Us About Climate Change? Michael G. Loso, Anthony Arendt, Chris Larsen, Nate with the fact that the state's many glaciers are changing. Many glaciers are shrinking, and "retreat" of the glacier terminus is usually the most obvious manifestation of that change. But while some glaciers (like

Loso, Michael G.

44

Seasonal and altitudinal variations in snow algal communities on an Alaskan glacier (Gulkana glacier in the Alaska range)  

NASA Astrophysics Data System (ADS)

Snow and ice algae are cold tolerant algae growing on the surface of snow and ice, and they play an important role in the carbon cycles for glaciers and snowfields in the world. Seasonal and altitudinal variations in seven major taxa of algae (green algae and cyanobacteria) were investigated on the Gulkana glacier in Alaska at six different elevations from May to September in 2001. The snow algal communities and their biomasses changed over time and elevation. Snow algae were rarely observed on the glacier in May although air temperature had been above 0? C since the middle of the month and surface snow had melted. In June, algae appeared in the lower areas of the glacier, where the ablation ice surface was exposed. In August, the distribution of algae was extended to the upper parts of the glacier as the snow line was elevated. In September, the glacier surface was finally covered with new winter snow, which terminated algal growth in the season. Mean algal biomass of the study sites continuously increased and reached 6.3 10 ?l m-2 in cell volume or 13 mg carbon m-2 in September. The algal community was dominated by Chlamydomonas nivalis on the snow surface, and by Ancylonema nordenskildii and Mesotaenium berggrenii on the ice surface throughout the melting season. Other algae were less abundant and appeared in only a limited area of the glacier. Results in this study suggest that algae on both snow and ice surfaces significantly contribute to the net production of organic carbon on the glacier and substantially affect surface albedo of the snow and ice during the melting season.

Takeuchi, Nozomu

2013-09-01

45

Columbia Glacier, Alaska, photogrammetry data set, 1981-82 and 1984-85  

USGS Publications Warehouse

Photogrammetric processing of 12 sets of vertical aerial photography of the Columbia Glacier, Alaska, has measured the altitude and velocity fields of the lowest 14,000 m of the glacier during the periods of September 1981 to October 1982 and October 1984 to September 1985. The data set consists of the location of 3,604 points on the glacier, 1,161 points along the glacier terminus, and 1,116 points along the top of the terminus ice cliff. During the 1981 to 1985 period the terminus of the glacier receded 1,350 m, the ice near the terminus thinned at a rate of 18 m/year, and ice velocity near the terminus tripled, reaching as much as 6,000 m/year. (Author 's abstract)

Krimmel, R.M.

1987-01-01

46

Assessing the Response of Alaska's Glaciers to Post-Little Ice Age Climate Change  

NASA Astrophysics Data System (ADS)

A comprehensive survey of the eleven mountain ranges and three island areas in Alaska that presently support glaciers was conducted to determine how glaciers in each area have responded to post-Little Ice Age (LIA) climate change. Today, glaciers cover 5 percent of Alaska, about 75,000 sq. km., range in elevation from 6,000 m to below sea level, and span latitudes from south of 55 degrees N to north of 69 degrees N. During the LIA, Alaskan glaciers expanded significantly, covering 10 percent more area than today. Many different types of data were used to construct baselines and determine glacier change. These include: published descriptions of glaciers (1794 - 2000), historic and modern maps (1794 - 2000), aerial photography (1926 - 2001), ground photography (1884 - 2001), airborne radar (1981 - 1991), satellite radar (1978 - 1998), space photography (1984 - 1994), multi-spectral satellite imagery (1972 - 2001), aerial reconnaissance and field observations by the author (1968 - 2001), and various types of proxy data. Data available varied for each region and glacier. Every mountain range and island group investigated is characterized by significant glacier retreat, thinning, and/or stagnation, especially at lower elevations. At some locations, glaciers have completely disappeared during the twentieth century. In other areas, retreat that started as early as the early eighteenth century, has continued into the twenty-first century. Ironically, in several areas, retreat is resulting in the number of glaciers is actually increasing, but the volume and area of ice is decreasing. The key survey findings are: ALEXANDER ARCHIPELAGO, KODIAK ISLAND, ALEUTIAN ISLANDS: every glacier examined showed evidence of thinning and retreat. Some have disappeared since last being mapped in the mid-twentieth century; COAST MOUNTAINS, ST. ELIAS MOUNTAINS, CHUGACH MOUNTAINS, KENAI MOUNTAINS, WRANGELL MOUNTAINS, ALASKA RANGE, AND THE ALEUTIAN RANGE: more than 95 percent of glaciers ending below an elevation of 1,500 m are retreating, thinning, and/or stagnating. Some advancing glaciers have tidewater termini. The two largest glaciers, Bering and Malaspina Glaciers, are thinning and retreating, losing several cubic kilometers of ice each year to melting and calving; TALKEETNA MOUNTAINS, AHKLUN-WOOD RIVER MOUNTAINS, KIGLUAIK MOUNTAINS, AND THE BROOKS RANGE: every glacier examined is retreating. Some disappeared during the twentieth century. Glaciers at higher elevations show little or no change. Perhaps, at these locations, regional climate change has not resulted in temperatures being elevated to a level where they impact existing glacier ice. Increases in precipitation may also be compensating for increases in melting. Throughout Alaska, in response to post-Little Ice Age climate change, all but a few glaciers that descent below an elevation of 1,500 m have thinned, stagnated, and/or retreated. Of the nearly 700 named Alaskan glaciers, less than a dozen are currently advancing.

Molnia, B. F.

2001-12-01

47

Distribution and spawning dynamics of capelin (Mallotus villosus) in Glacier Bay, Alaska: A cold water refugium  

USGS Publications Warehouse

Pacific capelin (Mallotus villosus) populations declined dramatically in the Northeastern Pacific following ocean warming after the regime shift of 1977, but little is known about the cause of the decline or the functional relationships between capelin and their environment. We assessed the distribution and abundance of spawning, non-spawning adult and larval capelin in Glacier Bay, an estuarine fjord system in southeastern Alaska. We used principal components analysis to analyze midwater trawl and beach seine data collected between 1999 and 2004 with respect to oceanographic data and other measures of physical habitat including proximity to tidewater glaciers and potential spawning habitat. Both spawning and non-spawning adult Pacific capelin were more likely to occur in areas closest to tidewater glaciers, and those areas were distinguished by lower temperature, higher turbidity, higher dissolved oxygen and lower chlorophyll a levels when compared with other areas of the bay. The distribution of larval Pacific capelin was not sensitive to glacial influence. Pre-spawning females collected farther from tidewater glaciers were at a lower maturity state than those sampled closer to tidewater glaciers, and the geographic variation in the onset of spawning is likely the result of differences in the marine habitat among sub-areas of Glacier Bay. Proximity to cold water in Glacier Bay may have provided a refuge for capelin during the recent warm years in the Gulf of Alaska.

Arimitsu, M.L.; Piatt, J.F.; Litzow, M.A.; Abookire, A.A.; Romano, Marc D.; Robards, M.D.

2008-01-01

48

A Century of Retreat at Portage Glacier, South-Central Alaska  

USGS Publications Warehouse

Introduction: The Portage Glacier, in south-central Alaska, is viewed by thousands of visitors annually who come to the U.S. Forest Service Begich, Boggs Visitor Center located on the road system between Anchorage and Whittier, Alaska. During the past century, the terminus of the glacier has retreated nearly 5 kilometers to its present location (fig. 1). Like other glaciers that terminate in water, such as Columbia Glacier near Valdez or Mendenhall Glacier near Juneau, Portage Glacier has experienced accelerated retreats in recent decades that likely were initially triggered by climate change begun at the end of the Little Ice Age in the mid-1800s and subsequently controlled in recent history primarily by calving of the glacier terminus. Photographic records of the terminus covering 1914 until present day track the patterns of retreat. These data, coupled with USGS climate information collected from the southern end of the ice field, provide insight to the patterns of retreat that might be observed in the future.

Kennedy, Ben W.; Trabant, Dennis C.; Mayo, Lawrence R.

2006-01-01

49

Sediments Exposed by Drainage of a Collapsing Glacier-Dammed Lake Show That Contemporary Summer Temperatures and Glacier Retreat Exceed the Medieval Warm Period in Southern Alaska  

Microsoft Academic Search

In the mountains of southcentral Alaska, recent and widespread glacier retreat is well-documented, but few instrumental or proxy records of temperature are available to place recent changes in a long-term context. The Medieval Warm Period in particular, is poorly documented because subsequent Little Ice Age glacier advances destroyed much of the existing sedimentary record. In a rare exception, sudden and

M. G. Loso; R. S. Anderson; S. P. Anderson; P. J. Reimer

2007-01-01

50

Glacier Bay, Alaska, from the Ground, Air, and Space  

NASA Technical Reports Server (NTRS)

This tape uses a combination of video, three-dimensional computer imaging, and still photographs to provide a descriptive overview of the life-cycle and environmental effects of glaciers. An historical prospective of researchers and the contribution that they have made to the understanding of glaciers and Glacier Bay is presented. The data collected from these scientists have been documented and used by means of scientific visualization in the hope of learning how glacial activity relates to climate changes.

Hall, Dorothy K.

1997-01-01

51

Glacier Surge Mechanism: 1982-1983 Surge of Variegated Glacier, Alaska  

Microsoft Academic Search

The hundredfold speedup in glacier motion in a surge of the kind that took place in Variegated Glacier in 1982-1983 is caused by the buildup of high water pressure in the basal passageway system, which is made possible by a fundamental and pervasive change in the geometry and water-transport characteristics of this system. The behavior of the glacier in surge

Barclay Kamb; C. F. Raymond; W. D. Harrison; Hermann Engelhardt; K. A. Echelmeyer; N. Humphrey; M. M. Brugman; T. Pfeffer

1985-01-01

52

Subglacial drainage system changes of the Gulkana Glacier, Alaska: discharge and sediment load observations and modelling  

Microsoft Academic Search

Hydrological characteristics of englacial and subglacial drainage systems in Gulkana Glacier, Alaska, were examined by analysing temporal variations of discharge and sediment load in the proglacial Phelan Creek in 2001. From data plots on semi-log paper, it appeared appropriate to separate both discharge and sediment load into fast and slow components. The two components were possibly produced by two different

Daisaku Kido; Kazuhisa A. Chikita; Kenta Hirayama

2007-01-01

53

Assessing glacier response to changing climate using new and historical field observations on the Kahiltna Glacier in the Central Alaska Range  

NASA Astrophysics Data System (ADS)

Like many remote mountain ranges in Alaska, British Columbia and the Yukon, the Central Alaska Range is a highly glaciated but relatively sparsely monitored region in terms of glacier mass balance and meteorological ground measurements. To date, long-term trends and balance gradients are poorly known, though these are of particular importance for calibrating melt models and evaluating remote sensing techniques aimed at assessing glacier response to climate change. Among the best field-based data available for the region are approximately 20 years of National Park Service mass balance measurements on the Kahiltna Glacier. A land-terminating valley glacier with a wide range of altitudes and non-surge-type behavior, the Kahiltna Glacier is often taken as a benchmark for the current mass balance state of Central Alaska Range glaciers. However, mass balance has historically only been sampled at a single location on the glacier, allowing for the possibility of substantial scaling error when these findings are extrapolated spatially. Here we present an extended campaign of field-based observations on the Kahiltna Glacier in 2010 and 2011, used to expand data from the single National Park Service index site to the entire glacier in order to reconstruct the historical mass balance record. Measurements include summer melt at 13 ablation stake positions, winter accumulation surveys along a centerline and several lateral profiles, summer temperatures at five elevations, and meteorological variables such as incoming/reflected solar radiation and wind speed/direction at a representative ablation area site. Calibrated against the observed temperature gradients, a set of modeling tools has been developed for the glacier using a fully distributed positive degree day approach. Derived mass change estimates provide key information for assessing the little known state of health of Central Alaska Range glaciers. By serving as a template, balance and temperature gradients observed on the Kahiltna Glacier can enable mass balance estimates for other glaciers in the region with as little as a single stake measurement. Moreover, mass changes derived from this study will provide seasonal corrections to remote sensing estimates from repeat laser altimetry, and will assist in calibrating regionally downscaled GRACE gravimetry measurements. Ultimately, this research hopes to provide crucial information for determining past and current glacier melt evolution for the Kahiltna Glacier and Central Alaska Range glaciers as a whole.

Young, J. C.; Arendt, A. A.

2011-12-01

54

AK-03 ALASKA: AK-03 Columbia Glacier "Cliff" (Narrated)  

NSDL National Science Digital Library

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.

James Balog

55

Muir and Riggs Glaciers, Muir Inlet, Alaska - 2004  

USGS Multimedia Gallery

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...

56

Glacier Bay, Alaska, From the Ground, Air and Space  

NSDL National Science Digital Library

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.

1996-01-01

57

Response of glacier mass balance and discharge to future climate change, upper Susitna basin, Alaska  

NASA Astrophysics Data System (ADS)

As glaciers retreat, they highly alter the characteristics of the overall water budget of the larger drainage basin. Understanding and quantifying glacier melt is key to effectively project future changes in watershed-scale stream flow from glacierized landscapes. In glacierized Southcentral Alaska, the State of Alaska is reviving analyses of the Susitna River's hydroelectric potential and impact by supporting a multitude of field and modeling studies. Here, we focus on the response of discharge to projected climate change through the end-of-the century. The analyzed sub-catchment is largely untouched by humans, and covers an area of 2,230 km2 (740 - 4000 m a.s.l.) of which 25% is glacierized. We use a distributed temperature index model (DETIM), which uses daily air temperature and precipitation to compute runoff, ice and snow melt/accumulation. Model calibration included daily discharge and annual mass balance point measurements between 1955 and 2012. Output from the CCSM global climate model forced by three emission scenarios (A1B, A2 and B1) was downscaled to project future runoff and glacier mass balance until 2100. Depending on the climate scenario, runoff is projected to increase by 22 to 39% (yrs 2005-2100) due to increased mean annual air temperature ranging from 3.0 to 4.9C and precipitation increase between 23 and 34%. During the same period, the glaciers are projected to lose between 11 to 14% of their area. The future projections show no trend in winter glacier mass balance, but suggest an increasingly negative specific summer mass balance. The DETIM model, despite its hydrologic simplicity and focus on snow and ice melt and accumulation, is able to reproduce well the observations in basin discharge and glacier mass balance.

Aubry-Wake, C.; Hock, R.; Braun, J. L.; Zhang, J.; Wolken, G. J.; Liljedahl, A.

2013-12-01

58

Glacier changes in southeast Alaska and northwest British Columbia and contribution to sea level rise  

USGS Publications Warehouse

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.

Larsen, C.F.; Motyka, R.J.; Arendt, A.A.; Echelmeyer, K.A.; Geissler, P.E.

2007-01-01

59

The Effects of Changing Climate on Glaciers in the Central Alaska Range, Alaska, USA: A Case Study on the Kahiltna Glacier  

NASA Astrophysics Data System (ADS)

This study will develop a set of modeling tools to provide estimates of melt evolution for the Kahiltna Glacier and glaciers of the Central Alaska Range (CAKR), over a number of future climate change scenarios. To parameterize the model, field measurements of mass balance and meteorological variables are being collected on the Kahiltna Glacier. These measurements include winter accumulation surveys along both a centerline transect and several lateral profiles of the main glacier branch, and summer ablation measurements at ten centerline index locations spaced evenly over a range of elevations. Snow density measurements are also being recorded at three elevations. Temperature and relative humidity is being sampled at five of the index locations, and a full meteorological station (measuring temperature, humidity, wind speed and direction, snow accumulation, ice ablation, and solar radiation) will be positioned on the lower ablation area. Here we present preliminary results from the 2010 melt season, comparing data collected on the Kahiltna Glacier to measurements from nearby sites within the CAKR. Data from a single index site monitored by the National Park Service (NPS) is compared to the accumulation and ablation measurements taken at the ten sites visited during 2010 as part of this study, to show the NPS index sites representativeness at different elevations. Accumulation at these locations is also compared to a nearby snow telemetry (SNOTEL) site to determine whether there is a systematic offset between station data and conditions on the glacier. Lapse rates are calculated from temperature readings at five different elevations, for comparison with data from a meteorological station located in an adjacent glacier basin. From these analyses we provide a preliminary assessment of the extent to which our in situ measurements on the Kahiltna Glacier are representative of regional trends. The project will leverage 20 years of NPS mass balance data for the Kahiltna Glacier, as well as weather station data previously collected within the CAKR. Field measurements will also be supplemented with available remote sensing mass balance estimates from both the Gravity Recovery and Climate Experiment (GRACE) and aircraft laser altimetry. Results from the Kahiltna Glacier will be used to calibrate a meltwater runoff model for all glaciated areas within the CAKR. This research hopes to provide crucial information for determining current glacier conditions and the changes in meltwater runoff that can be expected over time.

Young, J. C.; Arendt, A. A.

2010-12-01

60

Status and Trends of Alaska NPS Glaciers: Workplan and Early Results Michael G. Loso1 Chris Larsen2 Anthony Arendt2 Nate Murphy2 Justin Rich2  

E-print Network

Status and Trends of Alaska NPS Glaciers: Workplan and Early Results Michael G. Loso1 · Chris the Project Glaciers cover about 75,000 km2 of Alaska's land surface and approximately one-quarter of those glaciers are located within National Park boundaries. To develop a more comprehensive understanding

Loso, Michael G.

61

Application of Near-Surface Geophysics to Problems in Glacier Dynamics, Pitted Outwash Plain Formation, and Glaciotectonics, Matanuska Glacier, Alaska  

NASA Astrophysics Data System (ADS)

From 2000 to 2004, near-surface geophysics data in various forms was collected near the active terminus of Matanuska Glacier, Alaska, to address several specific hypotheses and also provide general subsurface information in several relatively unsampled zones of the subsurface. (1) Seismic reflection data was collected on the glacier to test the predicted thickening of debris-rich basal ice in response to the motion of the glacier out of a localized overdeepening. The seismic data imaged the 5-to-10 meter thick basal ice at depths of 50-150 m, and clearly showed a 50 percent thicking--supporting the glaciohydraulic supercooling mechanism for basal ice formation. An interesting result of this basal-freeze-on mechanism of forced equilibrium is the concept of the "graded glacier" that has implications of sediment-pumping effects in response to changes in the surface slope of the glacier in response to climate change. (2) Seismic reflection, GPR, and electrical resistivity data were collected in a proximal pitted outwash plain abutting the active margin of Matanuska Glacier. These data indicate the presence of laterally continuous "slabs" of buried ice, in places possibly in duplex-like structures formed during readvances. The formation of thermokarst resulting in pits (sinkholes) in the surface of the outwash plain are therefore interpreted to result from preferential pathways of melting (relict moulins?) in the buried ice slabs, rather than from discreet blocks of ice. (3) 4-D GPR data (3-D through time) were collected at the terminus of Matanuska Glacier in an attempt to examine the formation of debris-flow-generated stratigraphy during the collapse of a portion of an ice-cored moraine complex. During a 30-m readvance of the glacier (2002-2003, between "snapshots" of data collection) glaciotectonic deformation of the moraine stratigraphy was observed. The GPR data indicate that the readvancing glacier impacted the rigid buried ice within the moraine, passively translating and deforming the overlying sediment in response to occasional brittle faulting and thrusting of the buried ice.

Baker, G. S.; Pyke, K.; Evenson, E.; Lawson, D.; Larson, G.; Alley, R. B.

2005-05-01

62

Monitoring change in the Bering Glacier region, Alaska: Using Landsat TM and ERS-1 imagery  

SciTech Connect

The Bering Glacier is the largest (5,180 km{sup 2}) and longest (191 km) glacier in continental North America. This glacier is one of about 200 temperate glaciers in the Alaska/Canada region that are known to surge. Surges at the Bering Glacier typically occur on a 20-30 year cycle. The objective of this project was to extract information regarding the position of the terminus of the glacier from historic aerial photography, early 20{sup th} century ground photography, Landsat Thematic Mapper (TM) satellite data, and European Space Agency, Synthetic Aperture RADAR (ERS-1 SAR) data and integrate it into a single digital database that would lend itself to change detection analysis. ERS-1 SAR data was acquired from six dates between 1992-95 and was terrain corrected and co-registered A single Landsat TM image from June 1991 was used as the base image for classifying land cover types. Historic locations of the glacier terminus were generated using traditional photo interpretation techniques from aerial and ground photography. The result of this platform combination, along with the historical data, is providing land managers with the unique opportunity to generate complete assessments of glacial movement this century and determine land cover changes which may impact wildlife and recreational opportunities.

Payne, J.F. [Bureau of Land Management, Anchorage, AK (United States); Coffeen, M. [Bureau of Land Management, Glennallen, AK (United States); Macleod, R.D. [Ducks Unlimited, Inc., Sacramento, CA (United States)] [and others

1997-06-01

63

The response of Black Rapids Glacier, Alaska, to the Denali earthquake rock avalanches  

NASA Astrophysics Data System (ADS)

We describe the impact of three simultaneous earthquake-triggered rock avalanches on the dynamics of Black Rapids Glacier, Alaska, by using spaceborne radar imagery and numerical modeling. We determined the velocities of the glacier before and after landslide deposition in 2002 by using a combination of ERS-1/ERS-2 tandem, RADARSAT-1, and ALOS PALSAR synthetic aperture radar data. Ice velocity above the debris-covered area of the glacier increased up to 14% after the earthquake but then decreased 20% by 2005. Within the area of the debris sheets, mean glacier surface velocity increased 44% within 2 years of the landslides. At the downglacier end of the lowest landslide, where strong differential ablation produced a steep ice cliff, velocities increased by 109% over the same period. By 2007, ice velocity throughout the debris area had become more uniform, consistent with a constant ice flux resulting from drastically reduced ablation at the base of the debris. Without further analysis, we cannot prove that these changes resulted from the landslides, because Black Rapids Glacier displays large seasonal and interannual variations in velocity. However, a full Stokes numerical ice flow model of a simplified glacier geometry produced a reversal of the velocity gradient from compressional to extensional flow after 5 years, which supports our interpretation that the recent changes in the velocity field of the glacier are related to landslide-induced mass balance changes.

Shugar, Dan H.; Rabus, Bernhard T.; Clague, John J.; Capps, Denny M.

2012-01-01

64

Evaluating glacier movement fluctuations using remote sensing: A case study of the Baird, Patterson, LeConte, and Shakes glaciers in central Southeastern Alaska  

NASA Astrophysics Data System (ADS)

Global Land Survey (GLS) data encompassing Landsat Multispectral Scanner (MSS), Landsat 5's Thematic Mapper (TM), and Landsat 7's Enhanced Thematic Mapper Plus (ETM+) were used to determine the terminus locations of Baird, Patterson, LeConte, and Shakes Glaciers in Alaska in the time period 1975-2010. The sequences of the terminuses locations were investigated to determine the movement rates of these glaciers with respect to specific physical and environmental conditions. GLS data from 1975, 1990, 2000, 2005, and 2010 in false-color composite images enhancing ice-snow differentiation and Iterative Self-Organizing (ISO) Data Cluster Unsupervised Classifications were used to 1) quantify the movement rates of Baird, Patterson, LeConte, and Shakes Glaciers; 2) analyze the movement rates for glaciers with similar terminal terrain conditions and; 3) analyze the movement rates for glaciers with dissimilar terminal terrain conditions. From the established sequence of terminus locations, movement distances were quantified between the glacier locations. Movement distances were then compared to see if any correlation existed between glaciers with similar or dissimilar terminal terrain conditions. The Global Land Ice Measurement from Space (GLIMS) data was used as a starting point from which glacier movement was measured for Baird, Patterson, and LeConte Glaciers only as the Shakes Glacier is currently not included in the GLIMS database. The National Oceanographic and Atmospheric Administration (NOAA) temperature data collected at the Petersburg, Alaska, meteorological station (from January 1, 1973 to December 31, 2009) were used to help in the understanding of the climatic condition in this area and potential impact on glaciers terminus. Results show that glaciers with similar terminal terrain conditions (Patterson and Shakes Glaciers) and glaciers with dissimilar terminal terrain conditions (Baird, Patterson, and LeConte Glaciers) did not exhibit similar movement rates. Glacier movement rates were greatest for glaciers whose terminuses were in fresh water (Patterson and Shakes Glaciers), less for those with terminuses in salt water (LeConte Glacier), and least for glaciers with terminuses on dry land (Baird Glacier).Based upon these findings, the presence of water, especially fresh water, at the terminal end of the Patterson and Shakes Glaciers had a greater effect on glacier movement than slope. Possible explanations for this effect might include a heat sink effect or tidal motions that hasten glacier disintegration in the ablation zone. In a heat sink scenario, the water bodies in which the Patterson and Shakes Glaciers terminus are located could act as a thermal energy transfer medium that increases glacier melting and subsequent retreat. On the other hand, tidal motions could act as horizontal and vertical push/pull forces, which increase the fracturing rate, calving, and subsequent retreat of glaciers terminus that are is salt water like the LeConte Glacier. Over the length of the study period, 1975 through 2010, there has been a 0.85C increase in annual air temperatures that, although may seem low, may prove important when determining glacial mass balance rates. Further studies are necessary to test these hypotheses to determine if a heat sink effect and tidal motions significantly affected the movement rates for the glaciers in this study area. An additional significant result of this study was the creation of shapefiles delineating the positions of the Shakes Glaciers that are being submitted to the Global Land Ice Measurements from Space (GLIMS) program for inclusion in their master worldwide glacier database.

Davidson, Robert Howard

65

Contribution of glacier runoff to freshwater discharge into the Gulf of Alaska  

USGS Publications Warehouse

Watersheds along the Gulf of Alaska (GOA) are undergoing climate warming, glacier volume loss, and shifts in the timing and volume of freshwater delivered to the eastern North Pacific Ocean. We estimate recent mean annual freshwater discharge to the GOA at 870 km3 yr-1. Small distributed coastal drainages contribute 78% of the freshwater discharge with the remainder delivered by larger rivers penetrating coastal ranges. Discharge from glaciers and icefields accounts for 47% of total freshwater discharge, with 10% coming from glacier volume loss associated with rapid thinning and retreat of glaciers along the GOA. Our results indicate the region of the GOA from Prince William Sound to the east, where glacier runoff contributes 371 km3 yr -1, is vulnerable to future changes in freshwater discharge as a result of glacier thinning and recession. Changes in timing and magnitude of freshwater delivery to the GOA could impact coastal circulation as well as biogeochemical fluxes to near-shore marine ecosystems and the eastern North Pacific Ocean. Copyright ?? 2010 by the American Geophysical Union.

Neal, E.G.; Hood, E.; Smikrud, K.

2010-01-01

66

Muir and Riggs Glaciers, Muir Inlet, Alaska - 1950  

USGS Multimedia Gallery

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...

67

Glacier Ice Mass Fluctuations and Fault Instability in Tectonically Active Southern Alaska  

NASA Technical Reports Server (NTRS)

Across southern Alaska the northwest directed subduction of the Pacific plate is accompanied by accretion of the Yakutat terrane to continental Alaska. This has led to high tectonic strain rates and dramatic topographic relief of more than 5000 meters within 15 km of the Gulf of Alaska coast. The glaciers of this area are extensive and include large glaciers undergoing wastage (glacier retreat and thinning) and surges. The large glacier ice mass changes perturb the tectonic rate of deformation at a variety of temporal and spatial scales. We estimated surface displacements and stresses associated with ice mass fluctuations and tectonic loading by examining GPS geodetic observations and numerical model predictions. Although the glacial fluctuations perturb the tectonic stress field, especially at shallow depths, the largest contribution to ongoing crustal deformation is horizontal tectonic strain due to plate convergence. Tectonic forces are thus the primary force responsible for major earthquakes. However, for geodetic sites located < 10-20 km from major ice mass fluctuations, the changes of the solid Earth due to ice loading and unloading are an important aspect of interpreting geodetic results. The ice changes associated with Bering Glacier s most recent surge cycle are large enough to cause discernible surface displacements. Additionally, ice mass fluctuations associated with the surge cycle can modify the short-term seismicity rates in a local region. For the thrust faulting environment of the study region a large decrease in ice load may cause an increase in seismic rate in a region close to failure whereas ice loading may inhibit thrust faulting.

SauberRosenberg, Jeanne M.; Molnia, Bruce F.

2003-01-01

68

Hazard assessment of the Tidal Inlet landslide and potential subsequent tsunami, Glacier Bay National Park, Alaska  

Microsoft Academic Search

An unstable rock slump, estimated at 5 to 10???106m3, lies perched above the northern shore of Tidal Inlet in Glacier Bay National Park, Alaska. This landslide mass has the potential\\u000a to rapidly move into Tidal Inlet and generate large, long-period-impulse tsunami waves. Field and photographic examination\\u000a revealed that the landslide moved between 1892 and 1919 after the retreat of the

Gerald F. Wieczorek; Eric L. Geist; Roman J. Motyka; Matthias Jakob

2007-01-01

69

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

NASA Astrophysics Data System (ADS)

Glaciers around the globe are experiencing a notable retreat and thinning, triggered by atmospheric warming. Tidewater glaciers in particular have received much attention, because they have been recognized to contribute substantially to global sea level rise. However, lake calving glaciers in Alaska show increasingly high thinning and retreat rates and are therefore contributors to sea level rise. The number of such lake calving systems is increasing worldwide as land-terminating glaciers retreat into overdeepened basins and form proglacial lakes. Yakutat Glacier in Southeast Alaska is a low elevation lake calving glacier with an accumulation to total area ratio of 0.03. It experienced rapid thinning of 4.43 +/- 0.06 m w.e. yr-1 between 2000-2010 and terminus retreat of over 15 km since the beginning of the 20th century. Simultaneously, adjacent Yakutat Icefield land-terminating glaciers thinned at lower but still substantial rates (3.54 +/- 0.06 m w.e. yr -1 for the same time period), indicating lake calving dynamics help drive increased mass loss. Yakutat Glacier sustained a 3 km long floating tongue for over a decade, which started to disintegrate into large tabular icebergs in 2010. Such floating tongues are rarely seen on temperate tidewater glaciers. The floating ice was weakened by surface ablation, which then allowed rifts to form and intersect. Ice velocity from GPS measurements showed that the ice on the floating tongue was moving substantially faster than grounded ice, which was attributed to rift opening between the floating and grounded ice. Temporal variations of rift opening were determined from time-lapse imagery, and correlated well with variations in ice speeds. Larger rift opening rates occurred during and after precipitation or increased melt episodes. Both of these events increased subglacial discharge and could potentially increase the subaqueous currents towards the open lake and thus increase drag on the ice underside. Simultaneously, increased water input may cause lake level in rifts to rise resulting in faster rift propagation and spreading. Similar formation and disintegration of floating tongues are expected to occur in the glacier's future, as the ice divide lies below the current lake level. In addition to calving retreat, Yakutat Glacier is rapidly thinning, which lowers its surface and therefore exposes the ice to warmer air temperatures causing increased thinning. Even under a constant climate, this positive feedback mechanism would force Yakutat Glacier to quickly retreat and mostly disappear. Simulations of future mass loss were run for two scenarios, keeping the current climate and forcing it with a projected warming climate. Results showed that over 95% of the glacier ice will have disappeared by 2120 or 2070 under a constant vs projected climate, respectively. For the first few decades, the glacier will be able to maintain its current thinning rate by retreating and thus losing areas of lowest elevation. However, once higher elevations have thinned substantially, the glacier cannot compensate any more to maintain a constant thinning rate and transfers into an unstable run-away situation. To stop this collapse and transform Yakutat Glacier into equilibrium in its current geometry, air temperatures would have to drop by 1.5 K or precipitation would have to increase by more than 50%. An increase in precipitation alone is unlikely to lead to a stable configuration, due to the very small current accumulation area.

Trussel, Barbara Lea

70

Effect of glacier ablation on the Snettisham Hydroelectric Project, Long Lake and Crater Lake Basins, Alaska  

USGS Publications Warehouse

Long Lake Basin in the Snettisham Project Area southeast of Juneau, Alaska, yields water used for the production of hydroelectric power. Development of adjacent Crater Lake is planned to increase the Project 's generating capacity. Estimates of the hydroelectric potential of the lakes are based on streamflow records which are influenced by glaciers that cover 25% of the combined basins. Analysis of streamflow records shows that the quality and extent of records in the area are sufficient to predict flow from the Crater Creek basin with a fairly high degree of confidence. Comparison of aerial photographs indicates that glacier ablation and recession have been continuous since at least 1929. Estimates of ice-volume change from photogrammetric measurements indicate that less than 2.5% of the average runoff from the basins of Long and Crater Lakes has been from reduction in glacier-ice storage. (Author 's abstract)

Sloan, C.E.; Emery, P.A.; Fair, Diana

1986-01-01

71

Synoptic climatology reconstruction using ice core data from McCall Glacier, Alaska  

NASA Astrophysics Data System (ADS)

Ice cores have often been used to reconstruct paleoclimate based on proxies contained in the cores. Using an ice core from McCall Glacier, in the eastern Brooks Range of Alaska we attempt to determine relationships between ice core proxies and synoptic weather patterns influencing McCall Glacier. The method of self-organizing maps is used to objectively identify the synoptic patterns that influence Alaska. Results presented in this talk will focus on relationships between ice core proxies and synoptic weather patterns for the past 60 years, when reliable atmospheric reanalysis data is available. The focus will be on the warmest and coldest years observed at the McCall Glacier as represented in the NCEP/NCAR Reanalysis data to separate the synoptic circulation patterns most responsible for these years. An additional focus will be a seasonal analysis to determine if the warmest/coldest years are due primarily to temperatures in the cold or warm season. This relationship will then be extrapolated back in time when reanalysis data are not available to understand changes in synoptic patterns that are responsible for features observed in the ice core. The ultimate goal of this project is to relate climate change observed in northeastern Alaska over the past 250 years to the ice core proxies.

Cassano, E.; Cassano, J. J.; McConnell, J. R.; Nolan, M.

2011-12-01

72

Examining the Relationship between Surface Albedo and Glacier Mass Balance in the Central Alaska Range  

NASA Astrophysics Data System (ADS)

Surfaces with high reflectance values within the cryosphere such as seasonal snowpack, glacial snow and ice, and sea ice play a vital role in the global climate system and in the energy budgets of the world's glaciers. Changes in reflectance may induce feedbacks resulting in fluctuations of glacier mass balance. To understand the relationship between surface albedo and mass balance, we used an ASD Inc. FieldSpec4 spectroradiometer to measure incoming radiation, outgoing surface reflectance and optical grain size on the Kahiltna Glacier (Denali National Park, AK) during our field campaign this spring (May-June 2013). While on site, we installed two Campbell Scientific automatic weather stations; one communicates via Iridium telemetry. Comparison of our in situ data (reflectance, grain size and AWS measurements) to MODIS imagery will enable us to broaden our study area from the Kahiltna Glacier to the Central Alaska Range and to derive surface albedo values for the Range. Our final goal is to examine and quantify the relationship between our surface albedo calculations and glacier mass balance measurements from National Park Service and USGS studies. If the uncertainties are minimal, then we may apply this method of using surface albedo as a proxy for glacier mass balance in other remote regions where access is limited, but satellite imagery is available. Here we present the field albedo measurements, 6 months of the weather station data, and the MODIS-derived albedo. We will also present our findings on the relationship between the surface albedo and glacier mass balance. Quantifying the influence of albedo on mass balance will provide insight into the vulnerability of mountain glaciers to climate change, and their contribution to global sea level. Additionally, the results may offer valuable information for the enhancement of mass balance and energy balance models, temporally and spatially.

Godaire, T. P.; Kreutz, K. J.; Hamilton, G. S.; Burakowski, E. A.; Campbell, S. W.; Winski, D.; Wake, C. P.; Osterberg, E. C.; Markle, B. R.

2013-12-01

73

Alaska: Glaciers of Kenai Fjords National Park and Katmai National Park and Preserve (Chapter 12)  

NASA Technical Reports Server (NTRS)

Much recent research points to the shrinkage of the Earth's small glaciers, however, few studies have been performed to quantify the amount of change over time. We measured glacier-extent changes in two national parks in southeastern Alaska. There are hundreds of glaciers in Kenai Fjords National Park (KEFJ) and Katmai National Park and Preserve (KATM) covering over 2373 sq km of parkland. There are two primary areas of glaciation in KEFJ - the Harding Icefield and the Grewingk-Yalik Glacier Complex, and three primary areas of glaciation in KATM - the Mt. Douglas area, the Kukak Volcano to Mt. Katmai area and the Mt. Martin area. We performed glacier mapping using satellite imagery, from the 1970s, 1980s, and from 2000. Results of the analysis show that there has been a reduction in the amount of glacier ice cover in the two parks over the study period, of approximately 22 sq km of ice, approximately - 1.6% from 1986 to 2000 (for KEFJ), and of approximately 76 sq km of glacier ice, or about -7.7% from 1986187 to 2000 (for KATM). In the future, measurements of surface elevation changes of these ice masses should be acquired; together with our extent-change measurements, the volume change of the ice masses can then be determined to estimate their contribution to sea-level rise. The work is a continuation of work done in KEFJ, but in KATM, our measurements represent the first comprehensive study of the glaciers in this remote, little-studied area.

Giffen, Bruce A.; Hall, Dorothy K.; Chien, Janet Y.L.

2007-01-01

74

Debris Supply as a Control on the Development of Rock Glaciers in the Central Brooks Range, Alaska  

NASA Astrophysics Data System (ADS)

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 their source rockwalls, were analysed in terms of the following concepts. The deformation of a rock glacier can be represented by the shear stress in the creeping permafrost, using a pseudoplastic flow law for glacier ice. In addition, the long-term (i.e. more than several hundred years) deformation has been assumed to result in a steady state of the thickness of the rock glacier balancing with debris supply. Here, the size of the source rockwalls was assumed to mainly control the rate of debris supply. To satisfy these concepts and assumptions, parameters combined the sine of the average slope angle for a rock glacier with the normalised length of the source rockwall were prepared as values proportional to the velocity of the rock glacier. Then, these parameters for each rock glacier were compared with the normalised length of the rock glacier. A positive correlation between the parameters and length was found in the case of the active talus-derived rock glaciers, which implies that the debris supply from the rockwalls at least partly controls the size of the rock glaciers. In contrast, the combined parameters cannot explain the large size of glacier-derived and some inactive talus-derived rock glaciers. The location of these rock glaciers, however, indicates that glacial processes or catastrophic landslide effectively enlarged rock glaciers. Such an analysis focused on size variation of relict rock glaciers will be useful for discussing the glacial interaction and short-term (e.g. paraglacial) debris supply in paleo-permafrost environment.

Ikeda, A.; Yoshikawa, K.

2009-04-01

75

Passive microwave (SSM/I) satellite predictions of valley glacier hydrology, Matanuska Glacier, Alaska  

USGS Publications Warehouse

We advance an approach to use satellite passive microwave observations to track valley glacier snowmelt and predict timing of spring snowmelt-induced floods at the terminus. Using 37 V GHz brightness temperatures (Tb) from the Special Sensor Microwave hnager (SSM/I), we monitor snowmelt onset when both Tb and the difference between the ascending and descending overpasses exceed fixed thresholds established for Matanuska Glacier. Melt is confirmed by ground-measured air temperature and snow-wetness, while glacier hydrologic responses are monitored by a stream gauge, suspended-sediment sensors and terminus ice velocity measurements. Accumulation area snowmelt timing is correlated (R2 = 0.61) to timing of the annual snowmelt flood peak and can be predicted within ??5 days. Copyright 2008 by the American Geophysical Union.

Kopczynski, S.E.; Ramage, J.; Lawson, D.; Goetz, S.; Evenson, E.; Denner, J.; Larson, G.

2008-01-01

76

Seasonal and interannual variability of glacier mass loss in southern Alaska  

NASA Astrophysics Data System (ADS)

Alaska's climate is changing and one of the most significant indications of this change has been the late 19th to early 21st century behavior of Alaskan glaciers. Over the last decade, Gravity Recovery and Climate Experiment (GRACE) gravity measurements have enabled estimates of regional ice loss trends in glaciated southern Alaska. However, higher-resolution in situ, aircraft, GPS and other satellite data are being used to study the basin-scale processes responsible for the observed broad-scale seasonal and inter-annual variability of GRACE-derived mass change. Specifically we report on the use Moderate-resolution Imaging Spectroradiometer (MODIS) Land Surface Temperature (LST) and Fractional Snow Cover (FSC) products, at a spatial scale of 1 km or less, to document the temporal and spatial evolution of seasonal processes over a time period that includes the GRACE observations (2002 to present). We use observations of cryospheric change over the last decade as input to 3-D viscoelastic Earth models of southern Alaska. In addition to glacial changes on a variety of temporal and spatial scales, southern Alaska is tectonically active with frequent large earthquakes. The gravimetric response, as well as the rate and orientation of crustal deformation, due to relaxation processes associated with inter-annual snow/ice changes, glacier wastage on time scales of years to decades, and large earthquakes (1964 Prince William Sound, M=9.2, 2002 Denali, Mw=7.9) will be discussed.

Sauber, J. M.; Hall, D. K.; Han, S.; Luthcke, S. B.

2013-12-01

77

Glacier ice-volume modeling and glacier volumes on Redoubt Volcano, Alaska  

USGS Publications Warehouse

Assessment of ice volumes and hydrologic hazards on Redoubt Volcano began four months before the 1989-90 eruptions removed 0.29 cubic kilometer of perennial snow and ice from Drift glacier. A volume model was developed for evaluating glacier volumes on Redoubt Volcano. The volume model is based on third-order polynomial simulations of valley cross sections. The third-order polynomial is an interpolation from the valley walls exposed above glacier surfaces and takes advantage of ice-thickness measurements. The fortuitous 1989-90 eruptions removed the ice from a 4.5-kilometer length of Drift glacier, providing a unique opportunity for verification of the volume model. A 2.5-kilometer length was chosen in the denuded glacier valley and the ice volume was measured by digitally comparing two new maps: one derived from the most recent pre-eruption 1979 aerial photographs and the other from post-eruption 1990 aerial photographs. The measured volume in the reference reach was 99 x 106 cubic meters, about 1 percent less than was estimated by the volume model. The volume estimate produced by this volume model was much closer to the measured volume than was the volume estimated by other techniques. The verified volume model was used to evaluate the total volume of perennial snow and glacier ice on Redoubt Volcano, which was estimated to be 4.1?0.8 cubic kilometers. Substantial snow and ice covers on volcanoes exacerbate the hydrologic hazards associated with eruptions. The volume on Redoubt Volcano is about 23 times the volume that was present on Mount St. Helens before its 1980 eruption, which generated lahars and floods.

Trabant, Dennis C.; Hawkins, Daniel B.

1997-01-01

78

Turbidity-current channels in Queen Inlet, Glacier Bay, Alaska  

USGS Publications Warehouse

Queen Inlet is unique among Glacier Bay fjords because it alone has a branching channel system incised in the Holocene sediment fill of the fjord floor. Queen Inlet and other known channel-containing fjords are marine-outwash fjords; the tidewater glacial fjords do not have steep delta fronts on which slides are generated and may not have a sufficient reservoir of potentially unstable coarse sediment to generate channel-cutting turbidity currents. Presence or absence of channels, as revealed in the ancient rock record, may be one criterion for interpreting types of fjords. -Authors

Carlson, P.R.; Powell, R.D.; Rearic, D.M.

1989-01-01

79

Expanding Peatlands in Alaska Caused by Accelerated Glacier Melting Under a Warming Climate  

NASA Astrophysics Data System (ADS)

Most mountain glaciers worldwide have been retreating over the last century due to global warming. This is particularly true around the Gulf of Alaska, where glacier recession has further accelerated since 1988. It is well known that glacier meltwater plays a critical role in the global sea level rise, but its effects on structure and functioning of peatland ecosystems remain poorly understood. We have observed in the field that many peatlands in the Susitna Basin, south-central Alaska, are expanding. As high moisture conditions are needed to promote peatland development and expansion, a regional change toward wetter conditions is likely responsible for the ongoing paludification of these peatlands. However, instrumental climatic data from this region show no increase in precipitation but an increase in temperature (and presumably evaporation) over the last decades. We hypothesize that climatically-induced glacier melting is modifying the local/regional climate, especially air humidity during the growing season, promoting the expansion of peatlands. To document recent peatland vertical growth and lateral expansion, we collected two long peat cores and twelve 30-cm-long monoliths in 2008 along a 110-m transect from an expanding peatland margin toward the peatland center. Ecohydrologic changes were reconstructed from testate amoebae and plant macrofossils assemblages. Preliminary results from both long cores revealed a change in the vegetation assemblages from a mesotrophic fen dominated by sedges and brown mosses to a Sphagnum-dominated peat bog at 11 cm, suggesting a very recent modification of the local hydrologic regime. A simultaneous increase in moisture was reconstructed from testate amoebae records. These unusual shifts in peatland development and hydrology (e.g., wet conditions triggering the fen-bog transition) imply a recent increase of atmospheric water to these peatlands. Our ongoing lead-210 dating and additional proxy analysis will help us resolve the timing and nature of recent peatland changes. These data, together with glacier history and climate records, will allow us to further test our hypothesis that the increase in glacier meltwater is causing peatland expansion By acting as water sinks, peatlands located in glacierized watersheds may mediate the contribution of meltwater to present and future sea-level rise. Increases in peat accumulation rates due to favorable hydroclimatic conditions are also expected to promote carbon sequestration by these ecosystems. In contrast to the expected desiccation of peatlands under a warmer climate, enhanced growth due to glaciers-climate feedbacks in high-latitude regions may thus promote peatland expansion, even just temporally.

Loisel, J.; Yu, Z.; Jones, M. C.

2009-05-01

80

Methane seeps along boundaries of receding glaciers in Alaska and Greenland  

NASA Astrophysics Data System (ADS)

Glaciers, ice sheets, and permafrost form a 'cryosphere cap' that traps methane formed in the subsurface, restricting its flow to the Earth's surface and atmosphere. Despite model predictions that glacier melt and degradation of permafrost open conduits for methane's escape, there has been a paucity of field evidence for 'subcap' methane seepage to the atmosphere as a direct result of cryosphere disintegration in the terrestrial Arctic. Here, we document for the first time the release of sub-cryosphere methane to lakes, rivers, shallow marine fjords and the atmosphere from abundant gas seeps concentrated along boundaries of receding glaciers and permafrost thaw in Alaska and Greenland. Through aerial and ground surveys of 6,700 lakes and fjords in Alaska we mapped >150,000 gas seeps identified as bubbling-induced open holes in seasonal ice. Using gas flow rates, stable isotopes, and radiocarbon dating, we distinguished recent ecological methane from subcap, geologic methane. Subcap seeps had anomalously high bubbling rates, 14C-depletion, and stable isotope values matching microbial sources associated with sedimentary deposits and coal beds as well as thermogenic methane accumulations in Alaska. Since differential ice loading can overpressurize fluid reservoirs and cause sediment fracturing beneath ice sheets, and since the loss of glacial ice reduces normal stress on ground, opens joints, and activates faults and fissures, thereby increasing permeability of the crust to fluid flow, we hypothesized that in the previously glaciated region of Southcentral Alaska, where glacial wastage continues presently, subcap seeps should be disproportionately associated with neotectonic faults. Geospatial analysis confirmed that subcap seep sites were associated with faults within a 7 km belt from the modern glacial extent. The majority of seeps were located in areas affected by seismicity from isostatic rebound associated with deglaciation following the Little Ice Age (LIA; ca. 1650-1850 C.E.). Across Alaska, we found a relationship between methane stable isotopes, radiocarbon age, and distance to faults. Faults appear to allow the escape of deeper, more 14C-depleted methane to the atmosphere, whereas seeps away from faults entrained 14C-enriched methane formed in shallower sediments from microbial decomposition of younger organic matter. Additionally, we observed younger subcap methane seeps in lakes of Greenland's Sondrestrom Fjord that were associated with ice-sheet retreat since the LIA. These correlations suggest that in a warming climate, continued disintegration of glaciers, permafrost, and parts of the polar ice sheets will weaken subsurface seals and further open conduits, allowing a transient expulsion of methane currently trapped by the cryosphere cap.

Walter Anthony, K. M.; Anthony, P. M.; Grosse, G.; Chanton, J.

2012-12-01

81

Future glacier and runoff changes in the Upper Susitna basin, Alaska  

NASA Astrophysics Data System (ADS)

Traditionally, construction of hydropower dams have been guided by statistical flow analyses of historical discharge datasets. This assumes that the future hydrologic conditions (70+ years) will remain similar to what has been observed in the past. In glaciated Southcentral Alaska, the State is reviving studies of the Susitna River's hydroelectric potential. We combine field measurements and computational modeling to improve estimates of runoff into the proposed 81 km2 and 63 km long reservoir of the Susitna-Watana Hydroelectric Project. Approximately 4% the watershed area (14,774 km2) is glacierized. Changes in glacier extent in response to climate warming and/or altered precipitation regimes have the potential to substantially alter the magnitude and timing of runoff. Therefore, we apply the physically-based, fully distributed hydrologic model "Water Balance Simulation Model" (WaSiM). WaSiM is a well established tool for simulating the spatial and temporal variability of hydrologic processes in complex basins. The glacier module, which includes the shrinkage and expansion of glaciers, allows us to specifically evaluate the role of glacier melt on river runoff during the lifespan of the proposed dam. Here, the model is calibrated against multiple discharge and glacier mass balance measurements and is forced by daily temperature and precipitation grids. Downscaled climate projections serve to inform the hydrologic model in order to produce refined estimates of future seasonality and magnitude of flow. An application of a physically-based hydrologic model, which is first validated in order to quantify its uncertainty, has the potential to extend statistical analyses into the future and ultimately inform management decisions.

Braun, J. L.; Liljedahl, A. K.; Hock, R. M.; Wolken, G. J.

2012-12-01

82

The Propagation of a Surge Front on Bering Glacier, Alaska, 2001-2011  

NASA Technical Reports Server (NTRS)

Bering Glacier, Alaska, USA, has a 20 year surge cycle, with its most recent surge reaching the terminus in 2011. To study this most recent activity a time series of ice velocity maps was produced by applying optical feature-tracking methods to Landsat-7 ETM+ imagery spanning 2001-11. The velocity maps show a yearly increase in ice surface velocity associated with the down-glacier movement of a surge front. In 2008/09 the maximum ice surface velocity was 1.5 plus or minus 0.017 kilometers per a in the mid-ablation zone, which decreased to 1.2 plus or minus 0.015 kilometers per a in 2009/10 in the lower ablation zone, and then increased to nearly 4.4 plus or minus 0.03 kilometers per a in summer 2011 when the surge front reached the glacier terminus. The surge front propagated down-glacier as a kinematic wave at an average rate of 4.4 plus or minus 2.0 kilometers per a between September 2002 and April 2009, then accelerated to 13.9 plus or minus 2.0 kilometers per a as it entered the piedmont lobe between April 2009 and September 2010. Thewave seems to have initiated near the confluence of Bering Glacier and Bagley Ice Valley as early as 2001, and the surge was triggered in 2008 further down-glacier in the mid-ablation zone after the wave passed an ice reservoir area.

Turrin, James; Forster, Richard R.; Larsen, Chris; Sauber, Jeanne

2013-01-01

83

Comparison of geodetic and glaciological mass-balance techniques, Gulkana Glacier, Alaska, U.S.A  

USGS Publications Warehouse

The net mass balance on Gulkana Glacier, Alaska, U.S.A., has been measured since 1966 by the glaciological method, in which seasonal balances are measured at three index sites and extrapolated over large areas of the glacier. Systematic errors can accumulate linearly with time in this method. Therefore, the geodetic balance, in which errors are less time-dependent, was calculated for comparison with the glaciological method. Digital elevation models of the glacier in 1974, 1993 and 1999 were prepared using aerial photographs, and geodetic balances were computed, giving - 6.0??0.7 m w.e. from 1974 to 1993 and - 11.8??0.7 m w.e. from 1974 to 1999. These balances are compared with the glaciological balances over the same intervals, which were - 5.8??0.9 and -11.2??1.0 m w.e. respectively; both balances show that the thinning rate tripled in the 1990s. These cumulative balances differ by <6%. For this close agreement, the glaciologically measured mass balance of Gulkana Glacier must be largely free of systematic errors and be based on a time-variable area-altitude distribution, and the photography used in the geodetic method must have enough contrast to enable accurate photogrammetry.

Cox, L.H.; March, R.S.

2004-01-01

84

Late Holocene environmental change at three glacier-fed lakes, southern Alaska  

NASA Astrophysics Data System (ADS)

Lake-sediment cores and glacial geomorphology were used to infer late Holocene paleoenvironmental changes at three glacier-fed lakes across southern Alaska. The lakes form a 730-km-long transect around 60N lat, and they span the transition zone between two centers of opposite surface air-temperature responses attributed to fluctuations in the strength of the Aleutian Low, the primary indicator of winter climate in the North Pacific. Sediment cores from Hallet Lake in the NE Chugach Range display varying concentrations of biogenic silica (BSi), a measure of overall lake production. A transfer function was developed to infer summer temperature from downcore BSi content. The reconstruction shows clear evidence of first millennium AD cooling, warmth from 1300-1500 AD, Little Ice Age (LIA) cooling between 1750 and 1900 AD, and recent warming beginning ca. 1900 AD. During the last 30 yr, summer temperatures were nearly 2C warmer than the reconstructed mean of the past 2 millennia. Goat Lake is near treeline in the Kenai Mountains, and about 1 km from an outlet glacier of the Harding Icefield. Pollen assemblages show increasing abundances of mountain hemlock from 700-1200 AD, which we interpret as an expansion of treeline. The expansion was terminated around 1230 AD when 10 cm of tephra was deposited in the lake. Treeline above the modern and prior to the LIA is further indicated by a 14C age of 1470 85 AD on logs exposed below till at the present glacier terminus. By 1660 AD the outlet glacier thickened by 150 m where it overtopped its drainage divide and spilled meltwater into Goat Lake, which continued until around 1890 AD. Since then, hemlock pollen has increased to levels comparable to the 1200 AD peak, and the outlet glacier has retreated 1.4 km to the location of the 1470 AD logs. At Cascade Lake, sediment traps installed for 2 yr collected 77% less BSi when spring and summer temperatures were lower, suggesting that BSi flux in the lake is related to growing-season conditions. BSi was at its minimum early during the first millennium AD. It peaked around 700 AD, then decreased during the next 400 yr. BSi flux was relatively constant until the 19th century when it decreased to near-minima values, then attained its highest values of the last 2000 yr late during the 20th century. BSi and hemlock pollen are probably related more strongly to summer conditions than to winter, whereas glaciers respond to a combination of winter and summer climate variability. Late Holocene moraines in the forefields of cirque glaciers around all study lakes were mapped and dated roughly with lichenometry. The moraines delimit maximum glacier positions attained late in the 19th century, when glacier snouts generally descended less than 100 m in elevation relative to their 1950-1970 positions. This limited LIA expansion, together with tree-ring and other independent evidence for decades-long LIA summer cooling of at least 0.8C in south-central Alaska, indicates a reduction in accumulation-season precipitation during the LIA. A simultaneous reduction in winter precipitation across southern Alaska is difficult to ascribe to a shift in the Aleutian Low pressure system because instrumental data show dipolar responses across this region. This implies a longer- term, more general climate forcing that supersedes inter-decadal variability in the Aleutian Low.

Kaufman, D. S.; Anderson, R. S.; Daigle, T. A.; Kathan, K. M.; McKay, N. P.; Michelutti, N. N.; Werner, A.

2007-12-01

85

Iceberg calving during transition from grounded to floating ice: Columbia Glacier, Alaska  

USGS Publications Warehouse

The terminus of Columbia Glacier, Alaska, unexpectedly became ungrounded in 2007 during its prolonged retreat. Visual observations showed that calving changed from a steady release of low-volume bergs, to episodic flow-perpendicular rifting, propagation, and release of very large icebergs - a style reminiscent of calving from ice shelves. Here, we compare passive seismic and photographic observations through this transition to examine changes in calving. Mechanical changes accompany the visible changes in calving style post flotation: generation of seismic energy during calving is substantially reduced. We propose this is partly due to changes in source processes.

Walter, Fabian; O'Neel, Shad; McNamara, Daniel; Pfeffer, W.T.; Bassis, Jeremy N.; Fricker, Helen Amanda

2010-01-01

86

Modern pollen rain and vegetational history of the Malaspina Glacier district, Alaska  

NASA Astrophysics Data System (ADS)

Seventy surface pollen samples from coastal forest, coastal meadow, muskeg, tree line, and alpine tundra communities form a basis for interpreting fossil pollen assemblages in the Malaspina Glacier district, Alaska. Poflen and macrofossil analyses of three radiocarbon-dated fossil sections from Icy Cape indicate that vegetational changes resulting from plant succession can be distinguished from those of migrational and climatic origin. Vegetation of the early Holocene xerothermic interval (10,000-7600 yr B.P.) was dominated by Alnus communities. Wetter conditions ensued, enabling generative muskeg surfaces to develop and first Picea sitchensis, then Tsuga heterophylla to expand from areas southeastward. Climatic cooling in more recent millennia (3500 yr B.P. to the present) is indicated by the appearance and persistent growth of Tsuga mertensiana and Selaginella selaginoides along this portion of the Gulf of Alaska coastline.

Peteet, Dorothy M.

1986-01-01

87

Combined Ice and Water Balances of Gulkana and Wolverine Glaciers, Alaska, and South Cascade Glacier, Washington, 1965 and 1966 Hydrologic Years  

USGS Publications Warehouse

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

Meier, Mark Frederick; Tangborn, Wendell V.; Mayo, Lawrence R.; Post, Austin

1971-01-01

88

The break-up of a lacustrine floating ice tongue, Yakutat Glacier, Southeast Alaska  

NASA Astrophysics Data System (ADS)

Yakutat Glacier has been exposed to calving retreat for more than a century with a total terminus retreat of over 15 km since 1903. This temperate glacier in Southeast Alaska calves into over 300 m deep Harlequin Lake. Cold, non-stratified lake water with uniform temperatures of around 1 C combined with the large lake depth allowed this glacier to form a 17.2 km2 floating tongue. This floating tongue existed for over a decade between 2000 and 2010. Thinning in this terminus area exceeds 6 m during the summer. Digital elevation model differencing shows annual thinning rates of around 9 m yr-1 in the terminus area with a glacier wide mean of 4.070.03 m yr-1 (2007-2010). Calving rates are highly variable with periods of rapid retreat followed by periods of relative stability. The most recent period of rapid retreat began in 2010, when the floating tongue disintegrated into large tabular ice bergs. Those ice bergs calve as crevasses transform into rifts, a process supported by rapid thinning. Once the rifts intersect, large tabular icebergs are able to disconnect from the tongue and float away, generally without rolling over. This episodic style of calving also produces a large number of small ice bergs. Tidewater glaciers in the vicinity of Yakutat Glacier are exposed to a similar climate, but they neither form nor maintain a stable floating tongue, nor do they calve large tabular icebergs, even when retreating into over-deepened basins. We hypothesize that the different calving behavior is caused by the presence or absence of submarine melt as the glacier retreats into an over-deepening. In the case of a tidewater glacier, submarine melt can be large leading to instability and retreat. In a lacustrine system, subaquatic melt is negligible, allowing floating tongues to form. The recent break-up of this floating tongue shows certain similarities to the disintegration of ice shelves in Antarctica, but on a much smaller scale and in temperate ice. To better understand the rifting and calving processes during the break-up, we tracked rift opening with a time-lapse camera, monitored lake level and air temperature, and tracked ice surface displacement with GPSs. In addition, we recorded seismic data on near terminus bedrock, which show increased high frequency signals during calving events.

Truessel, B.; Truffer, M.; Motyka, R. J.; Larsen, C. F.

2012-12-01

89

Twenty-first century changes in the hydrology, glaciers, and permafrost of the Susitna Basin, Alaska  

NASA Astrophysics Data System (ADS)

In South-Central Alaska, the Susitna River is the site of a proposed hydroelectric dam. The catchment of the reservoir in the upper Susitna watershed (13,289 km^2, 450-4000 m a.s.l.) is 4% glacierized and is characterized by sparse vegetation, discontinuous permafrost, and little human development. Glaciers, permafrost, and the water cycle are expected to change in response to anticipated future atmospheric warming by the end of this century, thus impacting water yields to the hydroelectric reservoir. We aim to quantify future changes in glacier wastage, surface- and groundwater, permafrost, and evapotranspiration. We apply the physically-based hydrological model WaSiM using daily air temperature and precipitation data from station observations and gridded climate products. The model is calibrated with runoff and glacier mass balance measurements from the 1980s and validated with measurements from ongoing field campaigns which started in spring 2012. With the past and present data, the model is able to match both the magnitude and timing of observed river discharge. However, the scarcity of meteorological observations from the upper Susitna basin presents a major challenge to simulating the catchment hydrology. We present methods for extrapolation of the spatially-sparse long-term data across the catchment, with particular emphasis on high-elevation precipitation. To project future changes in river runoff, we run WaSiM with air temperature and precipitation downscaled from global climate models and compare results from several emission scenarios (selected from CMIP5). We discuss the anticipated changes in basin hydrology as the climate warms, permafrost thaws, and glaciers shrink.

Bliss, A. K.; Braun, J. L.; Daanen, R. P.; Hock, R.; Liljedahl, A.; Wolken, G. J.; Zhang, J.

2013-12-01

90

Hazard assessment of the Tidal Inlet landslide and potential subsequent tsunami, Glacier Bay National Park, Alaska  

USGS Publications Warehouse

An unstable rock slump, estimated at 5 to 10????????10 6 m3, lies perched above the northern shore of Tidal Inlet in Glacier Bay National Park, Alaska. This landslide mass has the potential to rapidly move into Tidal Inlet and generate large, long-period-impulse tsunami waves. Field and photographic examination revealed that the landslide moved between 1892 and 1919 after the retreat of the Little Ice Age glaciers from Tidal Inlet in 1890. Global positioning system measurements over a 2-year period show that the perched mass is presently moving at 3-4 cm annually indicating the landslide remains unstable. Numerical simulations of landslide-generated waves suggest that in the western arm of Glacier Bay, wave amplitudes would be greatest near the mouth of Tidal Inlet and slightly decrease with water depth according to Green's law. As a function of time, wave amplitude would be greatest within approximately 40 min of the landslide entering water, with significant wave activity continuing for potentially several hours. ?? 2007 Springer-Verlag.

Wieczorek, G.F.; Geist, E.L.; Motyka, R.J.; Jakob, M.

2007-01-01

91

Modeling energy balance and melt layer formation on the Kahiltna Glacier, Alaska  

NASA Astrophysics Data System (ADS)

Understanding melt on alpine glaciers is required both for accurate mass balance modeling and ice core paleoclimate reconstruction. In alpine regions with complex meteorology and topography, modeling melt through the quantification and balance of all identifiable energy fluxes is the most complete way of describing how local meteorology influences melt layer formation and snowpack evolution. To meet this goal at our field site on the Kahiltna glacier, located in the Central Alaska Range, Denali National Park, we have developed an energy balance model from two years of meteorological data from Kahiltna Base Camp (2100 m elevation, 63.25 degrees N, 151 degrees W). Current model results show the dominance of turbulent heat transfer at the study site and the importance of surface roughness and albedo in controlling melt. Preliminary data show a 30 percent overestimation of melt flux from the surface into the snowpack although an albedo submodel is being developed which may address this. Sampling of the snowpack across the glacier for analysis of stratigraphic and chemical evolution shows an isothermal near surface snowpack (to at least 1m) at 2100 meters in elevation in the early melt season with increasing density and melt layer abundance as the summer progresses. This suggests that a large amount of the meltwater remains in the snowpack after surface melting. We will discuss further the models accuracy in relation to ablation stake measurements as well as the major environmental controls on physical and chemical snowpack evolution into the melt season as additional results are processed.

Winski, D. A.; Kreutz, K. J.; Osterberg, E. C.; Campbell, S. W.; Denali Ice Core Team

2010-12-01

92

Glaciers  

NSDL National Science Digital Library

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.

Smoothstone

93

Glaciers  

NSDL National Science Digital Library

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.

2010-01-01

94

Relationship between large-scale circulation and ice core proxy data from the McCall Glacier, Alaska  

NASA Astrophysics Data System (ADS)

Ice cores have often been used to reconstruct paleoclimate based on proxies contained in the cores. Using an ice core from McCall Glacier, in the eastern Brooks Range of Alaska, we attempt to determine relationships between ice core proxies and synoptic weather patterns influencing McCall Glacier. The method of self-organizing maps is used to objectively identify the synoptic patterns that influence Alaska. Results presented in this talk will focus on relationships between ice core proxies and synoptic weather patterns for the past 50 years, when reliable atmospheric reanalysis data are available. The focus will be on annual accumulation and lead concentration from an ice core recovered from the McCall Glacier.

Cassano, E.; Cassano, J. J.; McConnell, J. R.; Nolan, M.

2013-12-01

95

The role of changing synoptic circulation patterns on the climate of McCall Glacier, Alaska  

NASA Astrophysics Data System (ADS)

A recently funded project is seeking to relate ice core proxies from McCall Glacier, Alaska to climate change in northeastern Alaska over the past 250 years. One goal of this project is to relate changes in synoptic weather patterns to signals recorded in the ice core. A synoptic climatology for this region has been constructed based on atmospheric reanalysis data using the method of self-organizing maps (SOMs). The synoptic climatology has identified 35 sea level pressure patterns that describe the range of synoptic conditions that influence this area. Temperature and precipitation anomalies are calculated for each pattern providing a link between the synoptic patterns and warm or cold and wet or dry days which influence the signal recorded in the ice core. The synoptic climatology is also used to assess the role of varying synoptic weather pattern frequency to observed changes in temperature and precipitation over the past 50 years. This analysis has been applied to a shift in climate centered on 1976 and also on recent (past 15 years) changes in climate in Alaska. The ultimate goal of this project is to identify a relationship between the ice core proxies and changes in the frequency of synoptic weather patterns that influenced the area during the last 50 years. With this relationship we hope to develop a paleo-synoptic climatology based on the full 250 year record contained in the ice core.

Cassano, E.; Cassano, J. J.; Nolan, M.

2010-12-01

96

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

SciTech Connect

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

Wiles, G.C. [Columbia Univ., Palisades, NY (United States); Calkin, P.E. [Univ. of New York, Buffalo, NY (United States); Post, A. [Geological Survey, Vashon, WA (United States)

1995-08-01

97

Using surface velocities to calculate ice thickness and bed topography: A case study at Columbia Glacier, Alaska, USA  

USGS Publications Warehouse

Information about glacier volume and ice thickness distribution is essential for many glaciological applications, but direct measurements of ice thickness can be difficult and costly. We present a new method that calculates ice thickness via an estimate of ice flux. We solve the familiar continuity equation between adjacent flowlines, which decreases the computational time required compared to a solution on the whole grid. We test the method on Columbia Glacier, a large tidewater glacier in Alaska, USA, and compare calculated and measured ice thicknesses, with favorable results. This shows the potential of this method for estimating ice thickness distribution of glaciers for which only surface data are available. We find that both the mean thickness and volume of Columbia Glacier were approximately halved over the period 19572007, from 281m to 143 m, and from 294 km3 to 134 km3, respectively. Using bedrock slope and considering how waves of thickness change propagate through the glacier, we conduct a brief analysis of the instability of Columbia Glacier, which leads us to conclude that the rapid portion of the retreat may be nearing an end.

McNabb, R.W.; Hock, R.; O'Neel, Shad R.; Rasmussen, L.A.; Ahn, Y.; Braun, M.; Conway, H.; Herreid, S.; Joughin, I.; Pfeffer, W.T.; Smith, B.E.; Truffer, M.

2012-01-01

98

Marine benthic habitat mapping of the West Arm, Glacier Bay National Park and Preserve, Alaska  

USGS Publications Warehouse

Seafloor geology and potential benthic habitats were mapped in West Arm, Glacier Bay National Park and Preserve, Alaska, using multibeam sonar, groundtruthed observations, and geological interpretations. The West Arm of Glacier Bay is a recently deglaciated fjord system under the influence of glacial and paraglacial marine processes. High glacially derived sediment and meltwater fluxes, slope instabilities, and variable bathymetry result in a highly dynamic estuarine environment and benthic ecosystem. We characterize the fjord seafloor and potential benthic habitats using the recently developed Coastal and Marine Ecological Classification Standard (CMECS) by the National Oceanic and Atmospheric Administration (NOAA) and NatureServe. Due to the high flux of glacially sourced fines, mud is the dominant substrate within the West Arm. Water-column characteristics are addressed using a combination of CTD and circulation model results. We also present sediment accumulation data derived from differential bathymetry. These data show the West Arm is divided into two contrasting environments: a dynamic upper fjord and a relatively static lower fjord. The results of these analyses serve as a test of the CMECS classification scheme and as a baseline for ongoing and future mapping efforts and correlations between seafloor substrate, benthic habitats, and glacimarine processes.

Hodson, Timothy O.; Cochrane, Guy R.; Powell, Ross D.

2013-01-01

99

Bedload component of glacially discharged sediment: Insights from the Matanuska Glacier, Alaska  

USGS Publications Warehouse

The flux of glacially derived bedload and the proportions of the suspended and bedload components carried by proglacial streams are highly debated. Published data indicate a large range-from 75%-in the bedload percentage of the total load. Two "vents," where supercooled subglacial meltwater and sediment are discharged, were sampled over the course of an entire melt season in order to quantify the flux of glacially delivered bedload at the Matanuska Glacier, Alaska. The bedload component contributed by these vents, for the one melt season monitored, is negligible. Furthermore, the bedload fluxes appear to be strongly supply limited, as shown by the poorly correlated discharge, bedload-flux magnitude, and grain-size caliber. Thus, in this case, any attempt to employ a predictive quantitative expression for coarse-sediment production based on discharge alone would be inaccurate. A nonglaciated basin proximal to the Matanuska Glacier terminus yielded higher bedload sediment fluxes and larger clast sizes than delivered by the two monitored vents. Such nonglaciated basins should not be overlooked as potentially major sources of coarse bedload that is reworked and incorporated into valley outwash.

Pearce, J.T.; Pazzaglia, F.J.; Evenson, E.B.; Lawson, D.E.; Alley, R.B.; Germanoski, D.; Denner, J.D.

2003-01-01

100

Columbia Glacier, Alaska recent ice loss and its relationship to seasonal terminal embayments, thinning and glacial flow  

USGS Publications Warehouse

In 1974 the U.S. Geological Survey began an intensive investigation of the stability of Columbia Glacier, a calving tidewater galcier terminating in Columbia Bay, near Valdez, Alaska. Aerial photographs taken in 1957 and a sequence of photographs taken at about 2-month intervals since 1976, when analyzed photogrammetrically, provided detailed data on changes in Columbia Glacier 's thickness, flow rate, and terminal position. Annual embayments in the glacier 's terminus form during the summer-autumn season in most years; the size of embayments appears to be related to (1) the thickness of the glacier, and (2) the position and nature of subglacial freshwater discharge. Embayments have apparently increased in size in recent years; the largest embayments yet observed formed in 1975, 1976, 1977, and 1978. From April 1, 1977, to April 1, 1978, the total volume of ice calved was about 1.0 cubic kilometer. By January 1979 the glacier front had retreated from Heather Island. Glacier flow varies seasonally and synchronously in the lower 17 kilometers of the glacier; large accelerations occur near the terminus in response to embayment formation. Daily speed within 5 kilometers of the terminus increased from about 1.9 meters per day between 1963 and 1968 to about 2.7 meters per day between 1977 and 1978. In the lowest 15 kilometers, the glacier surface was lowered about 9 meters between 1957 and 1974, and about 13 meters between 1974 and 1978. Columbia Glacier is being reduced in mass due, in part, to recent losses caused by large embayments forming annually. If such reduction continues it will result in a drastic retreat. (USGS)

Sikonia, W.G.; Post, Austin

1980-01-01

101

Hydrography and circulation of ice-marginal lakes at Bering Glacier, Alaska, U.S.A.  

USGS Publications Warehouse

An extensive suite of physical oceanographic, remotely sensed, and water quality measurements, collected from 2001 through 2004 in two ice-marginal lakes at Bering Glacier, Alaska-Berg Lake and Vitus Lake-show that each has a unique circulation controlled by their specific physical forcing within the glacial system. Conductivity profiles from Berg Lake, perched 135 m a.s.l., show no salt in the lake, but the temperature profiles indicate an apparently unstable situation, the 4??C density maximum is located at 10 m depth, not at the bottom of the lake (90 m depth). Subglacial discharge from the Steller Glacier into the bottom of the lake must inject a suspended sediment load sufficient to marginally stabilize the water column throughout the lake. In Vitus Lake, terminus positions derived from satellite imagery show that the glacier terminus rapidly retreated from 1995 to the present resulting in a substantial expansion of the volume of Vitus Lake. Conductivity and temperature profiles from the tidally influenced Vitus Lake show a complex four-layer system with diluted (???50%) seawater in the bottom of the lake. This lake has a complex vertical structure that is the result of convection generated by ice melting in salt water, stratification within the lake, and freshwater entering the lake from beneath the glacier and surface runoff. Four consecutive years, from 2001 to 2004, of these observations in Vitus Lake show little change in the deep temperature and salinity conditions, indicating limited deep water renewal. The combination of the lake level measurements with discharge measurements, through a tidal cycle, by an acoustic Doppler Current Profiler (ADCP) deployed in the Seal River, which drains the entire Bering system, showed a strong tidal influence but no seawater entry into Vitus Lake. The ADCP measurements combined with lake level measurements established a relationship between lake level and discharge, which when integrated over a tidal cycle, gives a tidally averaged discharge ranging from 1310 to 1510 m3 s-1. ?? 2006 Regents of the University of Colorado.

Josberger, E.G.; Shuchman, R.A.; Meadows, G.A.; Savage, S.; Payne, J.

2006-01-01

102

Glaciers  

NSDL National Science Digital Library

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.

103

Discovery of 100-160-year-old iceberg gouges and their relation to halibut habitat in Glacier Bay, Alaska  

USGS Publications Warehouse

Side-scan sonar and multibeam imagery of Glacier Bay, Alaska, revealed complex iceberg gouge patterns at water depths to 135 m on the floor of Whidbey Passage and south to the bay entrance. These previously undiscovered gouges likely formed more than 100 years ago as the glacier retreated rapidly up Glacier Bay. Gouged areas free of fine sediment supported greater biodiversity of Pacific halibut Hippoglossus stenolepsis than nearby sediment-filled gouges, probably due to increased habitat complexity. Small Pacific halibut were forund more frequently in sediment-free gouged areas, presumably due to higher prey abundance. In contrast, large Pacific halibut were found more frequently on soft substrates such as sediment-filled gouges, where they could bury themselves and ambush prey.

Carlson, P.R.; Hooge, P.N.; Cochrane, G.R.

2005-01-01

104

Air temperature and precipitation data, Gulkana Glacier, Alaska, 1968-96  

USGS Publications Warehouse

Daily, monthly, and annual average air temperature and precipitation-catch data were recorded at Gulkana Glacier basin, Alaska, between October 1967 and September 1996. The data set is important because it provides long-term climate information from the highest year-round climatological recording site in Alaska. The daily air temperature data set is 96 percent complete. The daily precipitation data set is 83 percent complete; precipitation data for 1993-96 are missing. Annual data summaries are calculated for each hydrologic year, October 1 through September 30, for years that have 12 months of data. Monthly precipitation-catch and average air temperature summaries are calculated for months with nine or fewer daily records missing. The average annual air temperature recorded at the site from hydrologic year 1968 through 1996 was -4.1 degrees Celsius. The coldest recorded year was 1972 with an average annual temperature of -6.7 degrees Celsius. The warmest year was 1981 with an average annual temperature of -2.6 degrees Celsius. January 1971 was the coldest month with an average temperature of -20.8 degrees Celsius. July 1989 was the warmest month with an average temperature of 8.7 degrees Celsius. January 17, 1971, was the coldest day with an average temperature of -35.0 degrees Celsius. June 15, 1969, was the warmest day with an average temperature of 16.4 degrees Celsius. The average annual precipitation catch recorded at the site from hydrologic year 1968 through 1992 was 1,020 millimeters. The highest annual precipitation catch recorded was 1,572 millimeters in 1981; the lowest was 555 millimeters in 1969. The highest recorded monthly precipitation catch was 448 millimeters in July 1981 and in several different months no precipitation was recorded. The highest daily precipitation catch was 99 millimeters on September 12, 1972, and on many different dates no precipitation was recorded. Because of low gage-catch efficiency the reported annual precipitation-catch data are estimated to represent about 62 percent of the actual annual basin precipitation. Snowfall is the dominant form of precipitation on the glacier from September through mid-June.

Kennedy, Ben W.; Mayo, Lawrence R.; Trabant, Dennis C.; March, Rod S.

1997-01-01

105

Muir Glacier in Glacier Bay National Monument 1941  

USGS Multimedia Gallery

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...

106

Possible Asynchronous Glacial Expansion During Climatic Warming in the Holocene, Glacier Bay Region, Alaska  

NASA Astrophysics Data System (ADS)

Glacial expansion is commonly thought to occur during cold climatic periods whereas thinning and recession follow as the climate warms. However, data from Glacier Bay, Alaska, on the location and timing of ice margin positions suggest that ice growth of the terrestrial and tidewater systems continued long after warming began. Radiocarbon dating of trees overridden by glacial advance provide rates and positions of ice margins over the last 9500 years BP. Major periods of ice advance were initiated prior to 9500 yrs BP and continued through at least 6000 yrs BP. Similarly ice returned to the region around 4900 yrs BP and continued to expand apparently without interruption through 3200 yrs BP. Data from more recent periods of ice advance are not as well constrained but appear to suggest ice filled much of the bay, perhaps including parts of the ice mass remaining from the 4.9 K advance, during three separate periods including the Little Ice age. Current investigations are evaluating signals in the tree ring record for causes, including signals developed by external forcings such as El Nino, the Pacific Decadal Oscillation (PDO) and Arctic Oscillation(AO).

Lawson, D. E.; Finnegan, D. C.; Bigl, S. R.; Kopczynski, S. E.; Magilligan, F. J.

2003-12-01

107

Evaluate ERTS imagery for mapping and detection of changes of snowcover on land and on glaciers. [Cascade Range, Washington and Tweedsmuir Glacier, Alaska  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. The area of snowcover on 10 individual drainage basins in the North Cascades, Washington, has been determined by use of a semi-automatic radiance threshold technique. The result is a unique record of the changing water storage as snow in these important hydrologic units, the runoff of which is utilized for hydroelectric power, dilution of wastes and heat, support of salmon migration, and irrigation. These data allow a new type of hydrologic modelling to proceed which should permit more accurate forecasts of streamflow. A new technique has been developed for measuring snow-covered area or snowline altitude semi-automatically. This variable contour overlay method permits the snowcover to be matched efficiently to the best fit contour of altitude. The motion of the Yentna Glacier during the concluding phase of its surge was successfully measured by a flicker technique using images of two dates. It appears that displacements as small as 100 to 200 m can be measured. Motion of the Tweedsmuir Glacier in Alaska was measured using ERTS-1 images enlarged to 1:50,000. Changes detected included a shock wave moving down the glacier, the margin expanding, the moraine pattern deforming, and the marginal valley deepening.

Meier, M. F. (principal investigator)

1974-01-01

108

Sediments Exposed by Drainage of a Collapsing Glacier-Dammed Lake Show That Contemporary Summer Temperatures and Glacier Retreat Exceed the Medieval Warm Period in Southern Alaska  

NASA Astrophysics Data System (ADS)

In the mountains of southcentral Alaska, recent and widespread glacier retreat is well-documented, but few instrumental or proxy records of temperature are available to place recent changes in a long-term context. The Medieval Warm Period in particular, is poorly documented because subsequent Little Ice Age glacier advances destroyed much of the existing sedimentary record. In a rare exception, sudden and unexpected catastrophic drainage of a previously stable glacier-dammed lake recently revealed lacustrine stratigraphy that spans over 1500 years. Located near the Bagley Icefield in Wrangell-St. Elias National Park and Preserve, Iceberg Lake first drained in A.D. 1999 and has not regained a stable shoreline since that time. Rapid incision of the exposed lakebed provided subaerial exposure of annual laminations (varves, confirmed by radiogenic evidence) that record continuous sediment deposition from A.D. 442 to A.D. 1998. We present a recalculated master chronology of varve thickness that combines measurements from several sites within the former lake. Varve thickness in this chronology is positively correlated with northern hemisphere temperature trends and also with a local, ~600 year long tree ring width chronology. Varve thickness increases in warm summers because of higher melt, runoff, and sediment transport, and also because shrinkage of the glacier dam allows shoreline regression that concentrates sediment in the smaller lake. Relative to the entire record, varve thicknesses and implied summer temperatures were lowest around A.D. 600, high between A.D. 1000 and A.D. 1300, low between A.D. 1500 and A.D 1850, and highest in the late 20th century. Combined with stratigraphic evidence that contemporary jokulhlaups are unprecedented since at least A.D. 442, this record suggests that late 20th century warming was more intense, and accompanied by more extensive glacier retreat, than the Medieval Warm Period or any other time in the last 1500 years. We emphasize that the chronology presented here does not include the entire sedimentary history of the lake. Deeper sediments unexposed by the subaerial exposures we examined may extend this record of summer temperatures back to the onset of significant glaciation in this region. Traditional coring techniques could capture this record before ongoing erosion of the dry lakebed exports it to the Gulf of Alaska.

Loso, M. G.; Anderson, R. S.; Anderson, S. P.; Reimer, P. J.

2007-12-01

109

Glaciers  

NSDL National Science Digital Library

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.

Wendy Adams

2011-01-01

110

Quantifying periglacial erosion: Insights on a glacial sediment budget, Matanuska Glacier, Alaska  

USGS Publications Warehouse

Glacial erosion rates are estimated to be among the highest in the world. Few studies have attempted, however, to quantify the flux of sediment from the periglacial landscape to a glacier. Here, erosion rates from the nonglacial landscape above the Matanuska Glacier, Alaska are presented and compare with an 8-yr record of proglacial suspended sediment yield. Non-glacial lowering rates range from 1??8 ?? 0??5 mm yr-1 to 8??5 ?? 3??4 mm yr-1 from estimates of rock fall and debris-flow fan volumes. An average erosion rate of 0??08 ?? 0??04 mm yr-1 from eight convex-up ridge crests was determined using in situ produced cosmogenic 10Be. Extrapolating these rates, based on landscape morphometry, to the Matanuska basin (58% ice-cover), it was found that nonglacial processes account for an annual sediment flux of 2??3 ?? 1??0 ?? 106 t. Suspended sediment data for 8 years and an assumed bedload to estimate the annual sediment yield at the Matanuska terminus to be 2??9 ?? 1??0 ?? 106 t, corresponding to an erosion rate of 1??8 ?? 0??6 mm yr-1: nonglacial sources therefore account for 80 ?? 45% of the proglacial yield. A similar set of analyses were used for a small tributary sub-basin (32% ice-cover) to determine an erosion rate of 12??1 ?? 6??9 mm yr-1, based on proglacial sediment yield, with the nonglacial sediment flux equal to 10 ?? 7% of the proglacial yield. It is suggested that erosion rates by nonglacial processes are similar to inferred subglacial rates, such that the ice-free regions of a glaciated landscape contribute significantly to the glacial sediment budget. The similar magnitude of nonglacial and glacial rates implies that partially glaciated landscapes will respond rapidly to changes in climate and base level through a rapid nonglacial response to glacially driven incision. ?? 2009 John Wiley & Sons, Ltd.

O'Farrell, C. R.; Heimsath, A.M.; Lawson, D.E.; Jorgensen, L.M.; Evenson, E.B.; Larson, G.; Denner, J.

2009-01-01

111

Variations in Sr and Nd isotopic ratios of cryoconite on glaciers in Asia, Alaska, and Greenland  

NASA Astrophysics Data System (ADS)

Recent shrinkages of glacial mass are not only due to global warming, but also possibly to accumulation of cryoconite on the glacial surface. Cryoconite is a biogenic surface dust consisting of organic matter mainly derived from living microbes on the glaciers, and mineral particles originated from basal till and/or wind-blown dust. Since cryoconite is dark color, it can reduce surface albedo of glaciers and accelerate their melting. Thus, it is important to understand their sources and formation process on the glaciers. The characteristics of cryoconite vary among geographical locations. For example, there are small amounts of cryoconite on Arctic glaciers and their glacial surface is clean. In contrast, large amounts of cryoconite accumulate on Asian glaciers and their glacial surface appears very dirty. These differences in cryoconite are likely to affect on surface albedo and melting of each glacier. However, the formation process of cryoconite, especially origins of minerals and production process of organic matters are still not well understood. Stable isotopic ratios of strontium (Sr) and neodymium (Nd) provide a means of identifying sources of substances and have been commonly used in loess or sediment studies. Furthermore, Sr isotope has been used as a tracer of Ca ion in studies of geochemical process, because its chemical characteristics are similar to Ca. Thus, Sr in organic matter including such organisms on the glacier may reveal their nutrient sources and ecology of them. In this study, we analyzed Sr and Nd isotopic ratios of four mineral and organic fractions in cryoconite on Asian and Polar glaciers. Based on the isotopic ratios, we identified origins of minerals in cryoconite and mineral sources used as nutrients by microbes on the glaciers. Sr and Nd isotopic ratios in the mineral fractions, especially silicate minerals, which are major components of mineral particles, vary significantly among the glaciers. Cryoconite on Asian glaciers showed higher Sr and lower Nd ratios in the north and also showed little variation within a glacier. On the other hand, those on Alaskan glacier showed lower Sr and large spatial variation in Nd on a glacier. Cryoconite on Greenlandic glaciers showed further high Sr and low Nd than the other glaciers. This suggests that origins of silicate minerals in cryoconite are substantially different among the glaciers. Compared with the isotopic ratios of silicate minerals in moraine, desert, and loess reported over the regions, those in cryoconite on Asian, Alaskan, and Greenlandic glaciers were close to those in respective regions. This result indicates that silicate minerals in cryoconite were derived from surrounding the glaciers. The Sr isotopic ratios of organic matter in cryoconite also varied among the glaciers. They may reflect the minerals used by glacial microbes as nutrients.

Nagatsuka, N.; Takeuchi, N.; Nakano, T.

2012-12-01

112

A continental shelf sedimentary record of Little Ice Age to modern glacial dynamics: Bering Glacier, Alaska  

NASA Astrophysics Data System (ADS)

The Bering Glacier System is the world's largest surging temperate glacier with seven events occurring over the past century under a range of north Pacific climatic conditions. Onshore records reveal changes in glacial termini positions and evidence of late Holocene glacial advances, but the Little Ice Age (LIA) record of potential glacial surging and associated flooding has not been examined. A 13.6 m-long jumbo core collected on the adjacent continental shelf reveals a 600-yr-long record of sedimentation associated with changing glacifluvial discharge. The chronology is based on 210Pb geochronology and five radiocarbon dates, and the core can be separated into three distinct lithologic units based on the examination of X-radiographs and physical properties: (1) an uppermost unit dating from ?125 cal yr BP to the present characterized by bioturbated mud interbedded with laminated, thick (5-20 cm) low-bulk density clay-rich beds; (2) a middle unit dating from ?120-400 cal yr BP that includes numerous interlaminated-to-interbedded low- and high-bulk density beds with infrequent evidence of bioturbation; thick laminated clay-rich beds are rare; (3) a lowermost unit that predates ?400 cal yr BP and is composed of rare laminated beds grading down into mottled to massive mud. In each of these units, the laminated lithofacies from this mid-shelf location indicates both flood deposition and likely sediment transport in the wave-current bottom-boundary layer. The thick low-density, clay-rich beds in the uppermost unit correlate with historic outburst floods associated with known surge events. Based on previous terrestrial studies, the terminus was at its Holocene Neoglacial maximum extent close to the modern coastline at some point in the middle to late stages of the LIA in southern Alaska (100-350 cal yr BP). During the LIA, preservation of bioturbated intervals is rare while laminated intervals are common. This style of interbedding indicates frequent (<10 yr recurrence interval) event-scale mud deposition, suggesting that frequent summer flooding and redistribution by winter storms were more prevalent during the LIA rather than the outburst flooding typical of the past century. Rare event-scale bedding indicative of outburst flooding and possible surge events is found within the middle unit, and may correspond to periods with similar climatic trends as in the 20th century. The infrequent deposition of event layers in the lowermost unit could be attributed to the less frequent flooding and/or enhanced diversion of glacial drainage to the eastern terminus instead of present day Seal River. The thickness and depositional frequency of event-scale bedding can be related to Gulf of Alaska tree-ring proxy temperature reconstructions, where more numerous event bed formation occurs when there are more frequent, higher-amplitude temperature excursions. These frequent fluctuations may have prevented the decadal-long periods of positive mass balance required to enable numerous surge events during this period.

Jaeger, John M.; Kramer, Branden

2014-09-01

113

Hydrometeorology and basal sliding on the Kennicott Glacier, Alaska, USA: Evidence for seasonal, diurnal, and event-scale glacier velocity fluctuations due to varying meltwater inputs and precipitation events  

NASA Astrophysics Data System (ADS)

We examine GPS-derived glacier ice surface velocities along with on- and near-glacier hydrometeorologic data to investigate the linkage between subglacial hydrology and basal sliding on the Kennicott Glacier in southeastern Alaska. Connections between ice dynamics and glacier hydrology remain poorly understood, yet are critical for understanding and forecasting modern sea level rise. In addition, basal sliding is an important process in glacial erosion and, therefore, alpine landscape evolution. We differentially process 30-second GPS data at four monuments along the glacier centerline over the 2012 and 2013 melt seasons. In addition, we overwinter one GPS monument on the glacier, allowing us to observe glacier behavior through a full annual cycle. We monitor stage on ice-marginal lakes, supraglacial streams, and the outlet river with pressure transducers and timelapse cameras. In both years we observe complex early season hydrologic behavior, with a ice-marginal lake draining and filling many times before emptying for the season. This likely records the interplay between varying melt inputs and the evolution of the glacier's ability to transmit flow subglacially. Concurrent with these stage variations, we observe large diurnal velocity fluctuations superimposed on a sustained increase in glacier velocity, likely reflecting the glacier's sensitivity to melt inputs in the early season. In 2012, we observe glacier velocity during the annual outburst flood of Hidden Creek Lake, which drains ~25106 m3 of water beneath the Kennicott Glacier. The flood hydrograph from an ice-marginal lake shows remarkable consistency from year to year despite differences in the timing of the flood and meteorology leading up to the jkulhlaup. As the flood wave passes through the glacier, ice surface velocity increases from ~0.3 m d-1 to ~1.5 m d-1 for a short time. We see speedups of a similar magnitude in autumn 2012 that appear to correlate precipitation events. In addition, we analyze ten years of high-resolution (~0.5 m pixel) satellite imagery to identify and characterize the evolution of moulins, which serve as point inputs to the glacier hydrologic system. We validate a number of satellite-identified moulins with field observations and characterize the diurnal cycle of meltwater inputs into one moulin via salt dilution discharge estimates. We extract glacier surface velocity fields from these satellite images, which provide a context for our GPS-derived point velocities. We investigate this suite of data in light of radar estimates of ice thickness and bed topography to better understand the importance and effect of glacier hydrology on basal sliding of the Kennicott Glacier.

Armstrong, W. H.; Anderson, R. S.; Pettit, E. C.; Rajaram, H.

2013-12-01

114

Mendenhall Glacier (Juneau, Alaska) icequake seismicity and its relationship to the 2012 outburst flood and other environmental forcing  

NASA Astrophysics Data System (ADS)

Glacial outburst floods occur when ice-dammed lakes or other reservoirs on the glacier release large volumes of water usually due to the failure of an ice dam. In 2011 and 2012 these types of floods have occurred at Mendenhall Glacier in Southeast Alaska, 15 km northwest of Juneau. The floods emanated from a lake within a remnant branch of Mendenhall Glacier, called Suicide Basin, and rapidly changed the levels of Mendenhall Lake. Homes on the shore of Mendenhall Lake were threatened by rapidly rising lake levels during such floods. We analyze data from a set of 4 short and broadband period seismometers placed in ice-boreholes in an array on Mendenhall Glacier for a period of 4 months in 2012. We also examine the outburst flood that occurred between July 4th and 8th 2012. We first manually pick icequakes as high-frequency bursts recorded by at least two stations. Next, we use a matched-filter technique to help complete the icequake record by detecting missed events with similar waveforms to those hand-picked events. While high-frequency noise was present during the flooding, the impulsive icequake activity did not appear to be modulated significantly during periods of flooding, suggesting that the flooding does not significantly deform the overlying ice. Impulsive icequake activity appears to show strongly diurnal periodicity, indicating that the icequakes were mainly caused by expansion/contraction of ice during daytime. We also analyze the activity in concert with GPS velocity and meteorological data from the area. By analyzing the temporal and spatial patterns of the events we hope to reveal more about the fundamental processes occurring beneath Mendenhall Glacier.

Morgan, P. M.; Walter, J. I.; Peng, Z.; Amundson, J. M.; Meng, X.

2013-12-01

115

Alaska: Glaciers of Kenai Fjords National Park and Katmai and Lake Clark National Parks and Preserve  

NASA Technical Reports Server (NTRS)

There are hundreds of glaciers in Kenai Fjords National Park (KEFJ) and Katmai National Park and Preserve (KATM) covering over 2276 sq km of park land (circa 2000). There are two primary glacierized areas in KEFJ -- the Harding Icefield and the Grewingk-Yalik Glacier Complex, and three primary glacierized areas in KATM - the Mt. Douglas area, the Kukak Volcano to Mt. Katmai area and the Mt. Martin area. Most glaciers in these parks terminate on land, though a few terminate in lakes. Only KEFJ has tidewater glaciers, which terminate in the ocean. Glacier mapping and analysis of the change in glacier extent has been accomplished on a decadal scale using satellite imagery, primarily Landsat data from the 1970s, 1980s, and from 2000. Landsat Multispectral Scanner (MSS), Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) imagery was used to map glacier extent on a park-wide basis. Classification of glacier ice using image processing software, along with extensive manual editing, was employed to create Geographic Information System (GIS) outlines of the glacier extent for each park. Many glaciers that originate in KEFJ but terminate outside the park boundaries were also mapped. Results of the analysis show that there has been a reduction in the amount of glacier ice cover in the two parks over the study period. Our measurements show a reduction of approximately 21 sq km, or -1.5% (from 1986 to 2000), and 76 sq km, or -7.7% (from 1986/87 to 2000), in KEFJ and KATM, respectively. This work represents the first comprehensive study of glaciers of KATM. Issues that complicate the mapping of glacier extent include: debris-cover (moraine and volcanic ash), shadows, clouds, fresh snow, lingering snow from the previous season, and differences in spatial resolution between the MSS and TM or ETM+ sensors. Similar glacier mapping efforts in western Canada estimate mapping errors of 3-4%. Measurements were also collected from a suite of glaciers in KEFJ and KATM detailing terminus positions and rates of recession using datasets including the 15-minute USGS quadrangle maps (1950/1951), Landsat imagery (1986/1987, 2000, 2006) and 2005 Ikonos imagery (KEFJ only).

Giffen, bruce A.; Hall, Dorothy K.; Chien, Janet Y. L.

2011-01-01

116

Alaska: Glaciers of Kenai Fjords National Park and Katmai National Park and Preserve  

NASA Technical Reports Server (NTRS)

There are hundreds of glaciers in Kenai Fjords National Park (KEFJ) and Katmai National Park and Preserve (KATM) covering over 2,276 sq km of park land (ca. 2000). There are two primary glacierized areas in KEFJ (the Harding Icefield and the Grewingk-Yalik Glacier Complex) and three primary glacierized areas in KATM (the Mt. Douglas area, the Kukak Volcano to Mt. Katmai area, and the Mt. Martin area). Most glaciers in these parks terminate on land, though a few terminate in lakes. Only KEFJ has tidewater glaciers, which terminate in the ocean. Glacier mapping and analysis of the change in glacier extent has been accomplished on a decadal scale using satellite imagery, primarily Landsat data from the 1970s, 1980s, and from2000. Landsat Multispectral Scanner (MSS),Thematic Mapper (TM), and Enhanced Thematic Mapper Plus (ETM) imagery was used to map glacier extent on a park-wide basis. Classification of glacier ice using image-processing software, along with extensive manual editing, was employed to create Geographic Information System (GIS)outlines of the glacier extent for each park. Many glaciers that originate in KEFJ but terminate outside the park boundaries were also mapped. Results of the analysis show that there has been a reduction in the amount of glacier ice cover in the two parks over the study period. Our measurements show a reduction of approximately 21 sq km, or 1.5(from 1986 to 2000), and 76 sq km, or 7.7 (from19861987 to 2000), in KEFJ and KATM, respectively. This work represents the first comprehensive study of glaciers of KATM. Issues that complicate the mapping of glacier extent include debris cover(moraine and volcanic ash), shadows, clouds, fresh snow, lingering snow from the previous season, and differences in spatial resolution between the MSS,TM, or ETM sensors. Similar glacier mapping efforts in western Canada estimate mapping errors of 34. Measurements were also collected from a suite of glaciers in KEFJ and KATM detailing terminus positions and rates of recession using datasets including 15 min USGS quadrangle maps(19501951), Landsat imagery (19861987, 2000,2006), and 2005 IKONOS imagery (KEFJ only).

Giffens, Bruce A.; Hall, Dorothy K.; Chien, Janet Y. L.

2014-01-01

117

Holocene history of Hubbard Glacier in Yakutat Bay and Russell Fiord, southern Alaska  

Microsoft Academic Search

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

David J. Barclay; Parker E. Calkin; Gregory C. Wiles

2001-01-01

118

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

USGS Publications Warehouse

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.

March, Rod S.; O'Neel, Shad

2011-01-01

119

In situ and satellite-derived ablation season temperature and surface characteristics of clean and debris-covered ice at Matanuska glacier, Alaska  

NASA Astrophysics Data System (ADS)

Outside of the ice sheets and the Himalayas, Alaska contains one of the largest masses of ice on Earth. The rapid loss of ice in Alaska in recent decades is the subject of intense investigation (Berthier et al., 2010). An under quantified factor in the understanding of ice mass loss is the role in which different surface glacier dust and debris types and thicknesses play on the ablation process. Ground-based measurements of surface temperature of several glacier debris types were collected in July 2012 at Matanuska glacier in Alaska. Wet, dry, moderately covered and cleaner ice sites were observed over a two week period. Temperatures were recorded every 20 minutes. Significant diurnal and debris type temperature variability were observed. Satellite-based shortwave and thermal infrared analysis of debris covered ice is used to estimate surface debris mineralogy. Thermal satellite data is further used to derive entire glacier surface temperatures. Terminal glacier in situ temperature observations are compared with satellite derived surface temperatures. In situ measurements are also evaluated with respect to Foster et al. (2012) physically based method for estimating surface glacier debris thickness. E. Berthier, E. Schiefer, G.K.C. Clarke, B. Menounos, F. Rmy, 2010, Contribution of Alaskan glaciers to sea-level rise derived from satellite imagery, Nature Geoscience, 3, 92-95. L.A. Foster, B.W. Brock, M.E.J. Cutler, F. Diotri, 2012, Instruments and Methods: A physically based method for estimating supraglacial debris thickness from thermal band remote-sensing data, Journal of Glaciology, 58, 210, 677-691.

Casey, K.

2012-12-01

120

Hubbard Glacier, Alaska: growing and advancing in spite of global climate change and the 1986 and 2002 Russell Lake outburst floods  

USGS Publications Warehouse

Hubbard Glacier, the largest calving glacier on the North American Continent (25 percent larger than Rhode Island), advanced across the entrance to 35-mile-long Russell Fiord during June 2002, temporarily turning it into a lake. Hubbard Glacier has been advancing for more than 100 years and has twice closed the entrance to Russell Fiord during the last 16 years by squeezing and pushing submarine glacial sediments across the mouth of the fiord. Water flowing into the cutoff fiord from mountain streams and glacier melt causes the level of Russell Lake to rise. However, both the 1986 and 2002 dams failed before the lake altitude rose enough for water to spill over a low pass at the far end of the fiord and enter the Situk River drainage, a world-class sport and commercial fishery near Yakutat, Alaska.

Trabant, Dennis C.; March, Rod S.; Thomas, Donald S.

2003-01-01

121

Southern Alaska as an Example of the Long-Term Consequences of Mountain Building Under the Influence of Glaciers  

NASA Technical Reports Server (NTRS)

Southern Alaska is a continent-scale region of ongoing crustal deformation within the Pacific-North American plate boundary zone. Glaciers and glacial erosion have dictated patterns of denudation in the orogen over the last approx. 5 My. The orogen comprises three discrete topographic domains from south to north, respectively: (1) the Chugach/St. Elias Range; (2) the Wrangell Mountains; and (3) the eastern Alaska Range. Although present deformation is distributed across the orogen, much of the shortening and uplift are concentrated in the Chugach/St. Elias Range. A systematic increase in topographic wavelength of the range from east to west reflects east-to-west increases in the width of a shallowly-dipping segment of the plate interface, separation of major upper plate structures, and a decrease in the obliquity of plate motion relative to the plate boundary. Mean elevation decays exponentially from approx. 2500 m to approx. 1100 m from east to west, respectively. Topographic control on the present and past distribution of glaciers is indicated by close correspondence along the range between mean elevation and the modern equilibrium line altitude of glaciers (ELA) and differences in the modern ELA, mean annual precipitation and temperature across the range between the windward, southern and leeward, northern flanks. Net, range- scale erosion is the sum of: (1) primary bedrock erosion by glaciers and (2) erosion in areas of the landscape that are ice-marginal and are deglaciated at glacial minima. Oscillations between glacial and interglacial climates controls ice height and distribution, which, in turn, modulates the locus and mode of erosion in the landscape. Mean topography and the mean position of the ELA are coupled because of the competition between rock uplift, which tends to raise the ELA, and enhanced orographic precipitation accompanying mountain building, which tends to lower the ELA. Mean topography is controlled both by the 60 deg latitude and maritime setting of active deformation and by the feedback between shortening and uplift, glacial erosion, and orographic effects on climate accompanying mountain building.

Meigs, Andrew; Sauber, Jeanne

2000-01-01

122

Preliminary hydrodynamic analysis of landslide-generated waves in Tidal Inlet, Glacier Bay National Park, Alaska  

USGS Publications Warehouse

A landslide block perched on the northern wall of Tidal Inlet, Glacier Bay National Park (Figure 1), has the potential to generate large waves in Tidal Inlet and the western arm of Glacier Bay if it were to fail catastrophically. Landslide-generated waves are a particular concern for cruise ships transiting through Glacier Bay on a daily basis during the summer months. The objective of this study is to estimate the range of wave amplitudes and periods in the western arm of Glacier Bay from a catastrophic landslide in Tidal Inlet. This study draws upon preliminary findings of a field survey by Wieczorek et al. (2003), and evaluates the effects of variations in landslide source parameters on the wave characteristics.

Geist, Eric L.; Jakob, Matthias; Wieczoreck, Gerald F.; Dartnell, Peter

2003-01-01

123

Calving Theory and the Thinning, Retreat, and Disarticulation of Bear Glacier, Alaska  

Microsoft Academic Search

Bear Glacier, with an area of ~225 km2, is a 25-km long valley glacier located in the southern Kenai Mountains. When first mapped in 1909, it had a piedmont lobe with an area of >30 km2. By the mid- 1980s, the terminus had retreated from 1-3 km, thinned by >150 m, and was actively calving small icebergs into an ice-marginal

B. F. Molnia

2007-01-01

124

An integrated geospatial approach to monitoring the Bering Glacier system, Alaska  

USGS Publications Warehouse

The Bering Glacier is the largest and longest glacier in continental North America, with an area of approximately 5,175 km2, and a length of 190 km. It is also the largest surging glacier in America, having surged at least five times during the twentieth century. The last surge of the Bering Glacier occurred in 1993-1995, since then, the glacier has undergone constant and significant retreat thereby expanding the boundaries of Vitus Lake and creating a highly dynamic system, both ecologically and hydrologically. This study utilized GIS to integrate remote sensing observations, with detailed bathymetric, hydrographic and in situ water quality measurements of the rapidly expanding Vitus Lake. Vitus Lake has nearly doubled in surface area from 58.4 km2 to 108.8 km2, with a corresponding increase in water volume from 6.1 km3 to 10.5 km3 over the same period. The remote sensing observations were used to direct a systematic bathymetric, hydrographic and water quality measurement survey in Vitus Lake which revealed a complex three dimensional structure that is the result of sea water inflow, convection generated by ice melting and the injection of fresh water from beneath the glacier.

Josberger, E.G.; Payne, J.; Savage, S.; Shuchman, R.; Meadows, G.

2004-01-01

125

Glacier Destruction and Lahar Generation during the 2009 Eruption of Redoubt Volcano, Alaska  

NASA Astrophysics Data System (ADS)

Two large lahars with volumes of 0.4-0.6 km3 and several smaller lahars with volumes of 0.05-0.1 km3 inundated the Drift River valley on the north flank of Redoubt Volcano during its 2009 eruption. Significant lahars were produced on March 22-23 during the initial explosive phase of the eruption following about 8 months of precursory unrest that included increased fumarolic melting of glacier ice and snow in the summit crater and upper Drift glacier. From the beginning of unrest in late July 2008 through March 20, 2009 about 3-7 x 106 m3 of glacier ice and snow were lost from upper Drift glacier as a result of fumarolic emissions and associated melting. Water and debris outflow during this period was minor and posed no downstream flow hazard beyond the base of the volcano. On March 22-23, explosive eruptions from a summit crater vent destroyed a significant amount of ice in upper Drift glacier and produced a funnel-shaped explosion crater within the larger summit crater. Glacier ice, 50-100 m thick, in the gorge below the vent was stripped to bedrock by pyroclastic flows and melt water. By the next available clear views of the volcano on March 26, about 0.5-1.0 x 108 m3 of ice had been removed from upper Drift glacier including part of the ice field in the summit crater. Melt water liberated by eruptive activity on March 22-23 also eroded or removed most of the river ice and snowpack present in the Drift River valley which may have added an additional 0.1-0.2 km3 of water to the lahars produced during that time. Additional explosions from March 26-April 4 caused further melting of Drift glacier and produced small lahars, but the extent of ice loss and lahar inundation during this period could not be determined because clouds obscured the volcano and much of the Drift River valley. The final explosive event and lahar of the eruption occurred on April 4 when pyroclastic flows produced by lava dome collapse swept over upper Drift glacier and a portion of its piedmont lobe. This event removed about 0.5-1.0 x 108 m3 of glacier ice and initiated a lahar, just slightly larger than the March 22-23 lahar, that inundated an area of about 125 km2 in the Drift River valley from the piedmont lobe to the Cook Inlet coastline about 35 km distant. Pre-eruptive Drift glacier ice volume was about 1 km3 and the total ice removed by the 2009 eruption was 0.1-0.2 km3 or about 10-20% of the total. The total amount of Drift glacier ice removed during the 1989-90 eruption was about 0.1 km3, roughly half of that removed during the 2009 eruption. The largest and most energetic event of the 1989-90 Redoubt eruption on January 2, 1990 removed about 0.25 x 108 m3 of ice from Drift glacier and initiated a lahar of about 0.2 km3, the largest of that eruption. Both the March 22-23 and April 4, 2009 events resulted in greater ice loss and larger lahars than did the January 2, 1990 event. The upper part of Drift glacier is narrow and confined by steep valley walls that restrict the lateral spreading of pyroclastic debris generated by lava dome collapse. This enhances the efficiency of ice melt by funneling pyroclastic flows over the glacier and mechanical erosion and thermal interaction leads to the production of large volumes of melt water and correspondingly large lahars downstream.

Waythomas, C. F.

2010-12-01

126

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

NASA Astrophysics Data System (ADS)

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

Dorava, Joseph M.; Milner, Alexander M.

2000-10-01

127

Streamflow changes in Alaska between the cool phase (1947-1976) and the warm phase (1977-2006) of the Pacific Decadal Oscillation: The influence of glaciers  

USGS Publications Warehouse

Streamflow data from 35 stations in and near Alaska were analyzed for changes between the cool phase (1947-1976) and the warm phase (1977-2006) of the Pacific Decadal Oscillation. Winter, spring, and summer flow changes and maximum annual flow changes were different for glaciated basins (more than 10% glacier-covered area) than for nonglaciated basins, showing the influence of glaciers on historical streamflowchanges. Mean February flows, for example, increased for the median of available stations by 45% for glaciated basins and by 17% for nonglaciated ones.

Hodgkins, Glenn A.

2009-01-01

128

Alaskan Glaciers and Glacier-Outburst Floods (Jkulhlaups)  

Microsoft Academic Search

Alaska has more than 50,000 glaciers, including about 2,000 valley glaciers. Nearly all Alaskan glaciers are temperate. Many Alaskan valley glaciers end in ice-marginal lakes formed by terminal or recessional moraines. Some Alaskan valley glaciers act as ice dams, forming lakes by blocking side valleys or by extending into adjacent valleys. Many Alaskan glaciers store large quantities of water in

B. F. Molnia

2009-01-01

129

Modeling energy balance and melt layer formation on the Kahiltna Glacier, Alaska  

Microsoft Academic Search

Understanding melt on alpine glaciers is required both for accurate mass balance modeling and ice core paleoclimate reconstruction. In alpine regions with complex meteorology and topography, modeling melt through the quantification and balance of all identifiable energy fluxes is the most complete way of describing how local meteorology influences melt layer formation and snowpack evolution. To meet this goal at

D. A. Winski; K. J. Kreutz; E. C. Osterberg; S. W. Campbell

2010-01-01

130

Radar Determination of Fiord Morphology, Bed Depths, and Ice Thickness - Bering Glacier, Alaska  

NASA Astrophysics Data System (ADS)

Details of fiord morphology and ice thickness determined from a 1991 USGS ice-surface, ice-penetrating radar (radio-echo sounding) survey of Bering Glacier's eastern piedmont lobe were confirmed and expanded by the addition of airborne monopod radar data, collected by NASA in 2008. The 1991 ice-penetrating radar measurements were made at 37 locations using a miniature high-power impulse transmitter, similar to one developed by Narod and Clarke (1994). The 1991 survey, reported by Molnia and Post (1995), determined: that a deep, sub-sea-level channel extended along the eastern side of the glacier, that parts of Bering Glacier's bed reached depths of at least 320 m below sea level, and that a sub-sea-level basin extended more than 50 km up-glacier from the terminus. Individual ice thickness measurements ranged from 195 m to 921 m. Bed depths ranged from 388 m above sea level to 320 m below sea level. Addition of the 2008 NASA data confirmed that at least two channels extended more than 300 m below sea level, underlying the terminus and parts of the eastern Bering Lobe. These include the eastern channel, located adjacent to the Grindle Hills, identified from the 1991 data, with maximum depths between 320 m and 347 m below sea level. A western channel, located adjacent to the Central Medial Moraine Band (CMMB), with maximum depths reaching between 361 m and 388 m below sea level was also located. At least two other channels reached 200 m or more below sea level. Intervening topographic highs extended above sea level. Limited data suggested that at least one channel extended under the CMMB and that at least two channels were located under the central part of the Steller Lobe, the western part of Bering Glacier's piedmont lobe, with a maximum measured depth of 369 m below sea level. The maximum ice thickness measured was 1024 m.

Molnia, B. F.; Snyder, L. E.

2013-12-01

131

Use of the Coastal and Marine Ecological Classification Standard (CMECS) for Geological Studies in Glacier Bay, Alaska  

NASA Astrophysics Data System (ADS)

The U S Geological Survey (USGS) is one of four primary organizations (along with the National Oceanographic and Atmospheric Administration, the Evironmental Protection Agency, and NatureServe) responsible for the development of the Coastal and Marine Ecological Classification Standard (CMECS) over the past decade. In June 2012 the Federal Geographic Data Committee approved CMECS as the first-ever comprehensive federal standard for classifying and describing coastal and marine ecosystems. The USGS has pioneered the application of CMECS in Glacier Bay, Alaska as part of its Seafloor Mapping and Benthic Habitat Studies Project. This presentation briefly describes the standard and its application as part of geological survey studies in the Western Arm of Glacier Bay. CMECS offers a simple, standard framework and common terminology for describing natural and human influenced ecosystems from the upper tidal reaches of estuaries to the deepest portions of the ocean. The framework is organized into two settings, biogeographic and aquatic, and four components, water column, geoform, substrate, and biotic. Each describes a separate aspect of the environment and biota. Settings and components can be used in combination or independently to describe ecosystem features. The hierarchical arrangement of units of the settings and components allows users to apply CMECS to the scale and specificity that best suits their needs. Modifiers allow users to customize the classification to meet specific needs. Biotopes can be described when there is a need for more detailed information on the biota and their environment. USGS efforts focused primarily on the substrate and geoform components. Previous research has demonstrated three classes of bottom type that can be derived from multibeam data that in part determine the distribution of benthic organisms: soft, flat bottom, mixed bottom including coarse sediment and low-relief rock with low to moderate rugosity, and rugose, hard bottom. The West Arm of Glacier Bay has all of these habitats, with the greatest abundance being soft, flat bottom. In Glacier Bay, species associated with soft, flat bottom habitats include gastropods, algae, flatfish, Tanner crabs, shrimp, sea pen, and other crustaceans; soft corals and sponge dominate areas of boulder and rock substrate. Video observations in the West Arm suggest that geological-biological associations found in central Glacier Bay to be at least partially analogous to associations in the West Arm. Given that soft, mud substrate is the most prevalent habitat in the West Arm, it is expected that the species associated with a soft bottom in the bay proper are the most abundant types of species within the West Arm. While mud is the dominant substrate throughout the fjord, the upper and lower West Arm are potentially very different environments due to the spatially and temporally heterogeneous influence of glaciation and associated effects on fjord hydrologic and oceanographic conditions. Therefore, we expect variations in the distribution of species and the development of biotopes for Glacier Bay will require data applicable to the full spectrum of CMECS components.

Cochrane, G. R.; Hodson, T. O.; Allee, R.; Cicchetti, G.; Finkbeiner, M.; Goodin, K.; Handley, L.; Madden, C.; Mayer, G.; Shumchenia, E.

2012-12-01

132

20th-century glacial-marine sedimentation in Vitus Lake, Bering Glacier, Alaska, U.S.A.  

USGS Publications Warehouse

Vitus Lake, the ice-marginal basin at the southeastern edge of Bering Glacier, Alaska, U.S.A., is a site of modern, rapid, glacial-marine sedimentation. Rather than being a fresh-water lake, Vitus Lake is a tidally influenced, marine to brackish embayment connected to the Pacific Ocean by an inlet, the Seal River. Vitus Lake consists of five deep bedrock basins, separated by interbasinal highs. Glacial erosion has cut these basins as much as 250 m below sea level. High-resolution seismic reflection surveys conducted in 1991 and 1993 of four of Vitus Lake's basins reveal a complex, variable three-component acoustic stratigraphy. Although not fully sampled, the stratigraphy is inferred to be primarily glacial-marine units of (1) basal contorted and deformed glacial-marine and glacial sediments deposited by basal ice-contact processes and submarine mass-wasting; (2) acoustically well-stratified glacial-marine sediment, which unconformably overlies the basal unit and which grades upward into (3) acoustically transparent or nearly transparent glacial-marine sediment. Maximum thicknesses of conformable glacial-marine sediment exceed 100 m. All of the acoustically transparent and stratified deposits in Vitus Lake are modern in age, having accumulated between 1967 and 1993. The basins where these three-part sequences of "present-day" glacial-marine sediment are accumulating are themselves cut into older sequences of stratified glacial and glacial-marine deposits. These older units outcrop on the islands in Vitus Lake. In 1967, as the result of a major surge, glacier ice completely filled all five basins. Subsequent terminus retreat, which continued through August 1993, exposed these basins, providing new locations for glacial-marine sediment accumulation. A correlation of sediment thicknesses measured from seismic profiles at specific locations within the basins, with the year that each location became ice-free, shows that the sediment accumulation at some locations exceeds 10 m year-1.

Molnia, B.F.; Post, A.; Carlson, P.R.

1996-01-01

133

Glacier Hazards From Space  

NSDL National Science Digital Library

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.

134

Accumulation Rate Variability and Winter Mass Balance Estimates using High Frequency Ground-Penetrating Radar and Snow Pit Stratigraphy on the Juneau Icefield, Alaska  

NASA Astrophysics Data System (ADS)

In July 2012, 200 km of 400 MHz ground-penetrating radar (GPR) profiles were collected across the Juneau Icefield, Alaska. The goal was to determine if spatial accumulation rate variability and winter mass balance estimates could be improved by linking stratigraphic features between yearly-excavated snow pits through GPR. Profiles were collected along the centerline and cross sections of the main branch, northwest, and Southwest branch of the Taku Glacier as well as the Mathes, Llewellyn, and Demorest Glaciers. Over 650 km^2 of area and 1000 m of elevation range were covered during this pilot project linking sixteen snow pits with GPR data across the icefield. The field work was conducted as part of the Juneau Icefield Research Program (JIRP) with hopes of continuing this method in future years if first year results show promise. As an annually operated field research and education program, JIRP creates a unique opportunity to provide significant future contributions to Alaska mass balance records if the program is continued. Signal penetration reached ? 25 m with maximum depths reached at higher elevations of the icefield. Conversely, minimal penetration occurred in wetter regions at lower elevations, likely caused by volume scattering from free water within the firn and ice. Ice lenses and the annual layer located in mass balance snow pits correlated well with continuous stratigraphy imaged in GPR profiles suggesting that the lenses are relatively uninterrupted across the icefield and that GPR may be an appropriate tool for extrapolating point mass balance pit depths in this part of Alaska. The Northwest and Southwest Branches of the Taku Glacier show a strong stratigraphic thinning gradient, west to east; the main trunk of the Taku Glacier which originates from the Mathes-Llewellyn ice divide showed a similar thinning from the divide to the ELA. The thinning displayed by all three glacier systems matches a typical gradient from accumulation zone to ELA. However, it is also likely that a local influx of accumulation at the higher elevations of the Southwest and Northwest Branches result from their close proximity of the ocean. Beyond mass balance estimates, radar profiles also revealed ablation horizons underlying the annual layer near the ELA. Monitoring the location of this ablation horizon relative to the annual balance reflector may be helpful in quantifying changes in the ELA at the end of each previous melt season. Perched water tables were also imaged in several locations which may be suitable for future hydrological studies focused on delineation of sub-glacial drainage systems and their impact on local glacier dynamics. This is a particularly interesting finding considering the unprecedented recent jokulhlaup of the Mendenhall Glacier and re-routing of the primary water drainage at the Llewellyn Glacier terminus in 2011.

Braddock, S. S.; Boucher, A. L.; Sandler, H. C.; McNeil, C.; Campbell, S. W.; Kreutz, K. J.

2012-12-01

135

Spatial pattern analysis of cruise ship-humpback whale interactions in and near Glacier Bay National Park, Alaska.  

PubMed

Understanding interactions between large ships and large whales is important to estimate risks posed to whales by ships. The coastal waters of Alaska are a summer feeding area for humpback whales (Megaptera novaeangliae) as well as a prominent destination for large cruise ships. Lethal collisions between cruise ships and humpback whales have occurred throughout Alaska, including in Glacier Bay National Park (GBNP). Although the National Park Service (NPS) establishes quotas and operating requirements for cruise ships within GBNP in part to minimize ship-whale collisions, no study has quantified ship-whale interactions in the park or in state waters where ship traffic is unregulated. In 2008 and 2009, an observer was placed on ships during 49 different cruises that included entry into GBNP to record distance and bearing of whales that surfaced within 1km of the ship's bow. A relative coordinate system was developed in ArcGIS to model the frequency of whale surface events using kernel density. A total of 514 whale surface events were recorded. Although ship-whale interactions were common within GBNP, whales frequently surfaced in front of the bow in waters immediately adjacent to the park (west Icy Strait) where cruise ship traffic is not regulated by the NPS. When ships transited at speeds >13 knots, whales frequently surfaced closer to the ship's midline and ship's bow in contrast to speeds slower than 13 knots. Our findings confirm that ship speed is an effective mitigation measure for protecting whales and should be applied to other areas where ship-whale interactions are common. PMID:21983996

Harris, Karin; Gende, Scott M; Logsdon, Miles G; Klinger, Terrie

2012-01-01

136

Spatial Pattern Analysis of Cruise Ship-Humpback Whale Interactions in and Near Glacier Bay National Park, Alaska  

NASA Astrophysics Data System (ADS)

Understanding interactions between large ships and large whales is important to estimate risks posed to whales by ships. The coastal waters of Alaska are a summer feeding area for humpback whales ( Megaptera novaeangliae) as well as a prominent destination for large cruise ships. Lethal collisions between cruise ships and humpback whales have occurred throughout Alaska, including in Glacier Bay National Park (GBNP). Although the National Park Service (NPS) establishes quotas and operating requirements for cruise ships within GBNP in part to minimize ship-whale collisions, no study has quantified ship-whale interactions in the park or in state waters where ship traffic is unregulated. In 2008 and 2009, an observer was placed on ships during 49 different cruises that included entry into GBNP to record distance and bearing of whales that surfaced within 1 km of the ship's bow. A relative coordinate system was developed in ArcGIS to model the frequency of whale surface events using kernel density. A total of 514 whale surface events were recorded. Although ship-whale interactions were common within GBNP, whales frequently surfaced in front of the bow in waters immediately adjacent to the park (west Icy Strait) where cruise ship traffic is not regulated by the NPS. When ships transited at speeds >13 knots, whales frequently surfaced closer to the ship's midline and ship's bow in contrast to speeds slower than 13 knots. Our findings confirm that ship speed is an effective mitigation measure for protecting whales and should be applied to other areas where ship-whale interactions are common.

Harris, Karin; Gende, Scott M.; Logsdon, Miles G.; Klinger, Terrie

2012-01-01

137

Evolving force balance at Columbia Glacier, Alaska, during its rapid retreat  

USGS Publications Warehouse

Changes in driving and resistive stresses play an essential role in governing the buoyancy forces that are important controls on the speed and irreversibility of tidewater glacier retreats. We describe changes in geometry, velocity, and strain rate and present a top-down force balance analysis performed over the lower reach of Columbia Glacier. Our analysis uses new measurements and estimates of basal topography and photogrammetric surface velocity measurements made between 1977 and 2001, while assuming depth-independent strain. Sensitivity tests show that the method is robust and insensitive to small changes in the calculation parameters. Spatial distributions of ice speed show little correspondence with driving stress. Instead, spatial patterns of ice speed exhibit a nonlinear correspondence with basal drag. Primary resistance to flow comes from basal drag, but lateral drag becomes increasingly more important throughout the retreat, which may account for observed increases in speed. Maximum basal drag is always located in a prominent constriction located ???12 km upstream from the preretreat terminus. Once the terminus retreated into deep water off the terminal moraine marking the modern maximum extent, the upstream location of this maximum basal drag helped to promote thinning and decrease effective pressure in the lower region by limiting replenishing ice flow from upstream. An increase in both ice velocity and calving resulted, initiating what appears to be an irreversible retreat. Copyright 2005 by the American Geophysical Union.

O'Neel, S.; Pfeffer, W.T.; Krimmel, R.; Meier, M.

2005-01-01

138

Quantifying Ice Marginal and Submarine Environments During Seasonal Advance and Retreat, Hubbard Glacier, Southeast Alaska USA  

NASA Astrophysics Data System (ADS)

Hubbard Glacier has been advancing into Disenchantment Bay for ~300 years and with its high accumulation area ratio (0.95) will likely continue to advance for the foreseeable future, barring an extreme change in climate increasing its ELA significantly. The continuing advance of Hubbard Glacier may create a permanent dam at Gilbert Point, a high bedrock ridge between Disenchantment Bay and Russell Fiord. To analyze the mechanics of ice dam formation and stability, we began investigating the channel environment in 2008 with multibeam swath bathymetry, side scan sonar, terrestrial scanning LiDAR and ADCP. These studies were done in combination with our ongoing (since 2005) motion surveys of the ice face, monitoring of climate and repeat time-lapse and satellite imaging of the terminus. Our dam site study took place in October when the Hubbard margin was near its seasonal minimum position and the channel was about 360 m wide in its narrowest section. The three-dimensional topography of the channel bed between the calving ice face and shoreline shows that it is mostly of low relief and shallow (< 40 m bsl) and that the active moraine at the base of the ice face lies at a relatively shallow depth (~ 5 to 25 m bsl) with 15 to 20 m local relief. Various subglacial and submarine features associated with both ice advance and retreat were also revealed. Streamlined and flow-related bedforms (flutes, scours, boulder-trains) suggest that the glacier largely slides across the channel bed, with limited deformation of underlying materials. In 2008, the ice face advanced at an average of ~ 3 m/d from March to May, slowing to about 1.5 m/d through the end of June when recession began; a submarine moraine marks this seasonal maximum position of 2008. Seasonal retreat of the ice margin at rates similar to those during the advance produced small morainal ridges at temporarily stable positions evident in our data. Previous years moraines were not preserved beyond the maximum ice position, probably being removed by strong tidal currents leaving only the coarsest boulders as a lag on the channel floor. Current velocity measured during our survey exceeded 5 m/s, with limited bed load evident and suggesting a hard and armored sea bed. The shallow sea bed and streamlined bedforms indicate relatively thin ice is advancing by sliding across the channel, in contrast with the much thicker central part of the terminal lobe which is advancing into a deep (> 250m) basin by morainal bank migration. These observations have important implications for the mechanics of ice dam closure and potential for long term stability.

Lawson, D. E.; Finnegan, D. C.; Waller, T.; Butler, W.; Gadomski, P.

2009-12-01

139

A 30-year record of surface mass balance (1966-95) and motion and surface altitude (1975-95) at Wolverine Glacier, Alaska  

USGS Publications Warehouse

Scientific measurements at Wolverine Glacier, on the Kenai Peninsula in south-central Alaska, began in April 1966. At three long-term sites in the research basin, the measurements included snow depth, snow density, heights of the glacier surface and stratigraphic summer surfaces on stakes, and identification of the surface materials. Calculations of the mass balance of the surface strata-snow, new firn, superimposed ice, and old firn and ice mass at each site were based on these measurements. Calculations of fixed-date annual mass balances for each hydrologic year (October 1 to September 30), as well as net balances and the dates of minimum net balance measured between time-transgressive summer surfaces on the glacier, were made on the basis of the strata balances augmented by air temperature and precipitation recorded in the basin. From 1966 through 1995, the average annual balance at site A (590 meters altitude) was -4.06 meters water equivalent; at site B (1,070 meters altitude), was -0.90 meters water equivalent; and at site C (1,290 meters altitude), was +1.45 meters water equivalent. Geodetic determination of displacements of the mass balance stake, and glacier surface altitudes was added to the data set in 1975 to detect the glacier motion responses to variable climate and mass balance conditions. The average surface speed from 1975 to 1996 was 50.0 meters per year at site A, 83.7 meters per year at site B, and 37.2 meters per year at site C. The average surface altitudes were 594 meters at site A, 1,069 meters at site B, and 1,293 meters at site C; the glacier surface altitudes rose and fell over a range of 19.4 meters at site A, 14.1 meters at site B, and 13.2 meters at site C.

Mayo, Lawrence R.; Trabant, Dennis C.; March, Rod S.

2004-01-01

140

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

SciTech Connect

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

Hunter, L.E.; Powell, R.D. (Northern Illinois Univ., Dekalb, IL (United States). Dept. of Geology)

1992-01-01

141

Effects of Bedrock Lithology and Subglacial Till on the Motion of Ruth Glacier, Alaska, Deduced from Five Pulses from 1973-2012  

NASA Technical Reports Server (NTRS)

A pulse is a type of unstable glacier flow intermediate between normal flow and surging. Using Landsat MSS, TM, and ETM+ imagery and feature tracking software, a time-series of mostly annual velocity maps from 1973 to 2012 was produced that reveals five pulses of Ruth Glacier, Alaska. Peaks in ice velocity were found in the 1981, 1989, 1997, 2003, and 2010; approximately every 7 years. During these peak years the ice velocity increased 300%, from approximately 40 m/yr to 160 m/yr, and occurred in an area of the glacier underlain by sedimentary bedrock. Based on the spatio-temporal behavior of Ruth Glacier during the pulse cycles, we suggest the pulses are due to enhanced basal motion via deformation of a subglacial till. The cyclical nature of the pulses is theorized to be due to a thin till, with low permeability, that causes incomplete drainage of the till between the pulses, followed by eventual recharge and dilation of the till. These findings suggest care is needed when attempting to correlate changes in regional climate with decadal-scale changes in velocity, because in some instances basal conditions may have a greater influence on ice dynamics than climate.

Turrin, J.; Forster, R.; Sauber, Jeanne; Hall, Dorothy K.; Bruhn, R.

2013-01-01

142

Diurnal discharge fluctuations and streambed ablation in a supraglacial stream on the Vaughan-Lewis and Gilkey glaciers, Juneau Icefield, Alaska  

SciTech Connect

The study reported here focuses on the dynamics of two supraglacial streams on the Juneau Icefield in southeast Alaska. Data on streambed ablation (melting) rates, stream discharge, radiation, and air temperature and humidity were collected in August 1990 and 1991. Radiation had the greatest effect on stream discharge. Daily peak discharges occurred only 30 minutes after peak radiation, but two hours after peak temperature. Factors influencing variation in discharge of the streams were velocity, stream depth, and stream width, in decreasing order of importance. Streambed ablation due to radiation was greater than glacier surface ablation due to radiation. Streambed ablation due to frictional heating was very small.

Stock, J.W. [Univ. of Canterbury, Christchurch (New Zealand). Dept. of Geology; [Pacific Science Center, Seattle, WA (United States). Foundation for Glacier and Environmental Research; Pinchak, A.C. [Case Western Reserve Univ., Cleveland, OH (United States). Mechanical and Aerospace Engineering; [Pacific Science Center, Seattle, WA (United States). Foundation for Glacier and Environmental Research

1995-12-31

143

UNIT, ALASKA.  

ERIC Educational Resources Information Center

THE UNIT DESCRIBED IN THIS BOOKLET DEALS WITH THE GEOGRAPHY OF ALASKA. THE UNIT IS PRESENTED IN OUTLINE FORM. THE FIRST SECTION DEALS PRINCIPALLY WITH THE PHYSICAL GEOGRAPHY OF ALASKA. DISCUSSED ARE (1) THE SIZE, (2) THE MAJOR LAND REGIONS, (3) THE MOUNTAINS, VOLCANOES, GLACIERS, AND RIVERS, (4) THE NATURAL RESOURCES, AND (5) THE CLIMATE. THE

Louisiana Arts and Science Center, Baton Rouge.

144

Disruption of Drift glacier and origin of floods during the 1989-1990 eruptions of Redoubt Volcano, Alaska  

USGS Publications Warehouse

Melting of snow and glacier ice during the 1989-1990 eruption of Redoubt Volcano caused winter flooding of the Drift River. Drift glacier was beheaded when 113 to 121 ?? 106 m3 of perennial snow and ice were mechanically entrained in hot-rock avalanches and pyroclastic flows initiated by the four largest eruptions between 14 December 1989 and 14 March 1990. The disruption of Drift glacier was dominated by mechanical disaggregation and entrainment of snow and glacier ice. Hot-rock avalanches, debris flows, and pyroclastic flows incised deep canyons in the glacier ice thereby maintaining a large ice-surface area available for scour by subsequent flows. Downvalley flow rheologies were transformed by the melting of snow and ice entrained along the upper and middle reaches of the glacier and by seasonal snowpack incorporated from the surface of the lower glacier and from the river valley. The seasonal snowpack in the Drift River valley contributed to lahars and floods a cumulative volume equivalent to about 35 ?? 106 m3 of water, which amounts to nearly 30% of the cumulative flow volume 22 km downstream from the volcano. The absence of high-water marks in depressions and of ice-collapse features in the glacier indicated that no large quantities of meltwater that could potentially generate lahars were stored on or under the glacier; the water that generated the lahars that swept Drift River valley was produced from the proximal, eruption-induced volcaniclastic flows by melting of snow and ice. ?? 1994.

Trabant, D.C.; Waitt, R.B.; Major, J.J.

1994-01-01

145

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

USGS Publications Warehouse

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

March, Rod S.

2003-01-01

146

Distribution of Ground-Nesting Marine Birds Along Shorelines in Glacier Bay, Southeastern Alaska: An Assessment Related to Potential Disturbance by Back-Country Users  

USGS Publications Warehouse

With the exception of a few large colonies, the distribution of ground-nesting marine birds in Glacier Bay National Park in southeastern Alaska is largely unknown. As visitor use increases in back-country areas of the park, there is growing concern over the potential impact of human activities on breeding birds. During the 2003i??05 breeding seasons, the shoreline of Glacier Bay was surveyed to locate ground-nesting marine birds and their nesting areas, including wildlife closures and historical sites for egg collection by Alaska Native peoples. The nesting distribution of four common ground-nesting marine bird species was determined: Arctic Tern (Sterna paradisaea), Black Oystercatcher (Haematopus bachmani), Mew Gull (Larus canus), and Glaucous-winged Gull (Larus glaucescens). Observations of less abundant species also were recorded, including Herring Gull (Larus argentatus), Red-throated Loon (Gavia stellata), Canada Goose (Branta canadensis), Willow Ptarmigan (Lagopus lagopus), Semipalmated Plover (Charadrius semipalmatus), Spotted Sandpiper (Actitis macularia), Least Sandpiper (Calidris minutilla), Parasitic Jaeger (Stercorarius parasiticus), and Aleutian Tern (Sterna aleutica). Nesting distribution for Arctic Terns was largely restricted to the upper arms of the bay and a few treeless islets in the lower bay, whereas Black Oystercatchers were more widely distributed along shorelines in the park. Mew Gulls nested throughout the upper bay in Geikie Inlet and in Fingers and Berg Bays, and most Glaucous-winged Gull nests were found at wildlife closures in the central and lower bays. Several areas were identified where human disturbance could affect breeding birds. This study comprises the first bay-wide survey for the breeding distribution of ground-nesting marine birds in Glacier Bay National Park, providing a minimum estimate of their numbers and distribution within the park. This information can be used to assess future human disturbance and track natural changes in nesting bird distribution over time.

Arimitsu, M.L.; Piatt, J.F.; Romano, Marc D.

2007-01-01

147

Alaskan Glaciers and Glacier-Outburst Floods (Jkulhlaups)  

NASA Astrophysics Data System (ADS)

Alaska has more than 50,000 glaciers, including about 2,000 valley glaciers. Nearly all Alaskan glaciers are temperate. Many Alaskan valley glaciers end in ice-marginal lakes formed by terminal or recessional moraines. Some Alaskan valley glaciers act as ice dams, forming lakes by blocking side valleys or by extending into adjacent valleys. Many Alaskan glaciers store large quantities of water in thermokarst lakes, crevasses, conduits, and cavities. Annually, all of these situations result in jkulhlaups. Draining of ice-dammed lakes or ice-marginal lakes causes most. Some jkulhlaups are produced by the release of water stored subglacially, englacially, or supraglacially, sometimes through surge-related processes. Less frequently, jkulhlaups result from the melting of glaciers located around the summit craters of many of Alaska's erupting volcanoes. Recently, all of these mechanisms have produced jkulhlaups that have effected resource development, fisheries, and infrastructure. In spite of Alaska's small population and large geographic area, annually Alaskan jkulhlaups cause millions of dollars of damage. In the last three decades, jkulhlaup events at Hubbard Glacier have produced two of the largest floods that have occurred anywhere on Earth in post-Pleistocene time. Two recent Bering Glacier jkulhlaups resulted in a flood lasting nearly a year and in the rapid lowering of an ice-dammed lake by more than 50 m. This presentation characterizes the scope of jkulhlaups that have recently occurred in Alaska, focusing on recent jkulhlaup events at Hubbard and Bering Glaciers and Mount Redoubt.

Molnia, B. F.

2009-04-01

148

Evaluate ERTS imagery for mapping and detection of changes of snowcover on land and on glaciers. [North Cascades, Washington and Tweedsmuir Glacier, Alaska  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. Snowlines on a small (6 sq km) drainage basin were accurately measured without use of digital processing, and snow patches as small as 150 m (maximum dimension) were correctly identified, proving that the resolution of ERTS is ample for snow mapping needs. The area of snow cover on 10 individual drainage basins in the North Cascades, Washington, has been determined at 12 different times; these data can be used for more accurate forecasts of streamflow. Progress has been made in distinguishing snow in trees using multispectral analysis. Motion of the surging Tweedsmuir Glacier was measured. Velocities ranged from 2 to 88 m per day; a zone of intense crevassing also appeared to spread up and down the glacier (at about 200 m per day upglacier). This tentative result may be of great importance to an understanding of surging glacier dynamics. ERTS images also show that the most recent debris flow (20-21 August 1973) from Mount Baker can be clearly discerned and mapped, in order to monitor this potential hazard.

Meier, M. F. (principal investigator)

1974-01-01

149

Response of glaciers in northwestern North America to future climate change: an atmosphere/glacier  

E-print Network

Response of glaciers in northwestern North America to future climate change: an atmosphere/glacier@gi.alaska.edu 2 HyMet, Inc., 13629 Burma Road SW, Vashon Island, WA 98070, USA ABSTRACT. The response of glaciers to changing climate is explored with an atmosphere/glacier hierarchical modeling approach, in which global

Bhatt, Uma

150

Fast tidewater glaciers  

NASA Astrophysics Data System (ADS)

Some iceberg-calving outlet glaciers flow continuously at speeds normally associated with surging glaciers arid exhibit dramatic instability scenarios related to those suggested for marine ice sheets. No temperate tidewater glaciers are known to have floating termini, but many polar and subpolar tidewater glaciers do. The fast flow of temperate calving glaciers is almost entirely due to basal sliding and appears to be a function of the effective pressure on the bed, which may approach zero, and the longitudinal back stress on the terminus. The terminus boundary condition (the calving relation) is imperfectly known yet is vital to the dynamics of these glaciers. Calving relations for grounded tidewater glaciers have been suggested on empirical grounds but have not been rigorously tested; the calving relations for floating termini are virtually unknown. This, together with the imperfect understanding of basal sliding, inhibits confidence in our understanding of the stability of these glaciers. Columbia Glacier (Alaska) is an instructive example because observations have been made on the major changes in its geometry, calving rate, and dynamics that have occurred in less than 10 years. The calving flux has increased more rapidly than the glacier flux, causing thinning and retreat; as a result, the ice velocity has increased markedly. The short-term velocity changes relate to changes in back pressure (ice recession, tidal changes) and the flux of water injected to the bed. These results have relevance to the mechanisms of basal sliding, glacier surges, and the stability of marine ice streams.

Meier, M. F.; Post, Austin

1987-08-01

151

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

USGS Publications Warehouse

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

March, Rod S.

2000-01-01

152

Dramatic increase in the relative abundance of large male dungeness crabs Cancer magister following closure of commercial fishing in Glacier Bay, Alaska  

USGS Publications Warehouse

The size structure of the population of the Dungeness crab Cancer magister was studied at six sites in or near Glacier Bay, Alaska, before and after the closure of commercial fishing. Seven years of preclosure and 4 years of postclosure data are presented. After the closure of Glacier Bay to commercial fishing, the number and size of legal-sized male Dungeness crabs increased dramatically at the experimental sites. Female and sublegal-sized male crabs, the portions of the population not directly targeted by commercial fishing, did not increase in size or abundance following the closure. There was not a large shift in the size-abundance distribution of male crabs at the control site that is still open to commercial fishing. Marine protected areas are being widely promoted as effective tools for managing fisheries while simultaneously meeting marine conservation goals and maintaining marine biodiversity. Our data demonstrate that the size of male Dungeness crabs can markedly increase in a marine reserve, which supports the concept that marine reserves could help maintain genetic diversity in Dungeness crabs and other crab species subjected to size-limit fisheries and possibly increase the fertility of females. ?? 2004 by the American Fisheries Society.

Taggart, S.J.; Shirley, T.C.; O'Clair, C. E.; Mondragon, J.

2004-01-01

153

Glacier Ecosystems of Himalaya  

NASA Astrophysics Data System (ADS)

Biological activity on glaciers has been believed to be extremely limited. However, we found various biotic communities specialized to the glacier environment in various part of the world, such as Himalaya, Patagonia and Alaska. Some of these glacier hosted biotic communities including various cold-tolerant insects, annelids and copepods that were living in the glacier by feeding on algae and bacteria growing in the snow and ice. Thus, the glaciers are simple and relatively closed ecosystems sustained by the primary production in the snow and ice. In this presentation, we will briefly introduce glacier ecosystems in Himalaya; ecology and behavior of glacier animals, altitudinal zonation of snow algal communities, and the structure of their habitats in the glacier. Since the microorganisms growing on the glacier surface are stored in the glacial strata every year, ice-core samples contain many layers with these microorganisms. We showed that the snow algae in the ice-core are useful for ice core dating and could be new environmental signals for the studies on past environment using ice cores. These microorganisms in the ice core will be important especially in the studies of ice core from the glaciers of warmer regions, in which chemical and isotopic contents are often heavily disturbed by melt water percolation. Blooms of algae and bacteria on the glacier can reduce the surface albedo and significantly affect the glacier melting. For example, the surface albedo of some Himalayan glaciers was significantly reduced by a large amount of dark-colored biogenic material (cryoconite) derived from snow algae and bacteria. It increased the melting rates of the surfaces by as much as three-fold. Thus, it was suggested that the microbial activity on the glacier could affect the mass balance and fluctuation of the glaciers.

Kohshima, S.; Yoshimura, Y.; Takeuchi, N.; Segawa, T.; Uetake, J.

2012-12-01

154

Mass balance, meteorological, ice motion, surface altitude, and runoff data at Gulkana Glacier, Alaska, 1992 balance year  

USGS Publications Warehouse

The 1992 measured winter snow, maximum winter snow, net, and annual balances in the Gulkana Glacier basin were evaluated on the basis of meteorological, hydrological, and glaciological data measured in the basin and are reported herein. Averaged over the glacier, the measured winter snow balance was 0.97 meters on March 26, 1992; the maximum winter snow balance was 1.05 meters on May 19, 1992; the net balance (from September 8, 1991 to August 17, 1992) was -0.29 meters; and the annual balance (October 1, 1991 to September 30, 1992) was -0.38 meters. Ice surface, motion, and altitude changes measured at three index sites document seasonal changes in ice speed and glacier thickness. Annual stream runoff was 1.24 meters averaged over the basin.

March, R.S.; Trabant, D.C.

1996-01-01

155

Mass balance, meteorological, ice motion, surface altitude, and runoff data at Gulkana Glacier, Alaska, 1994 balance year  

USGS Publications Warehouse

The 1994 measured winter snow, maximum winter snow, net, and annual balances in the Gulkana Glacier basin were evaluated on the basis of meteorological, hydrological, and glaciological data obtained in the basin. Averaged over the glacier, the measured winter snow balance was 1.34 meters on April 29, 1994, 0.9 standard deviation above the long-term average; the maximum winter snow balance, 1.43 meters, was reached on April 18, 1994; the net balance (from September 8, 1993 to September 17, 1994) was -0.72 meter, 0.7 standard deviation below the long-term average. The annual balance (October 1, 1992, to September 30, 1993) was -0.88 meter. Ice-surface motion and altitude changes measured at three index sites document seasonal ice speed and glacier-thickness changes. Annual stream runoff was 1.93 meters averaged over the basin, approximately equal to the long-term average.

March, Rod S.

1998-01-01

156

Alaska  

NASA Technical Reports Server (NTRS)

Though it's not quite spring, waters in the Gulf of Alaska (right) appear to be blooming with plant life in this true-color MODIS image from March 4, 2002. East of the Alaska Peninsula (bottom center), blue-green swirls surround Kodiak Island. These colors are the result of light reflecting off chlorophyll and other pigments in tiny marine plants called phytoplankton. The bloom extends southward and clear dividing line can be seen west to east, where the bloom disappears over the deeper waters of the Aleutian Trench. North in Cook Inlet, large amounts of red clay sediment are turning the water brown. To the east, more colorful swirls stretch out from Prince William Sound, and may be a mixture of clay sediment from the Copper River and phytoplankton. Arcing across the top left of the image, the snow-covered Brooks Range towers over Alaska's North Slope. Frozen rivers trace white ribbons across the winter landscape. The mighty Yukon River traverses the entire state, beginning at the right edge of the image (a little way down from the top) running all the way over to the Bering Sea, still locked in ice. In the high-resolution image, the circular, snow-filled calderas of two volcanoes are apparent along the Alaska Peninsula. In Bristol Bay (to the west of the Peninsula) and in a couple of the semi-clear areas in the Bering Sea, it appears that there may be an ice algae bloom along the sharp ice edge (see high resolution image for better details). Ground-based observations from the area have revealed that an under-ice bloom often starts as early as February in this region and then seeds the more typical spring bloom later in the season.

2002-01-01

157

Flow velocities of Alaskan glaciers.  

PubMed

Our poor understanding of tidewater glacier dynamics remains the primary source of uncertainty in sea level rise projections. On the ice sheets, mass lost from tidewater calving exceeds the amount lost from surface melting. In Alaska, the magnitude of calving mass loss remains unconstrained, yet immense calving losses have been observed. With 20% of the global new-water sea level rise coming from Alaska, partitioning of mass loss sources in Alaska is needed to improve sea level rise projections. Here we present the first regionally comprehensive map of glacier flow velocities in Central Alaska. These data reveal that the majority of the regional downstream flux is constrained to only a few coastal glaciers. We find regional calving losses are 17.1?Gt?a(-1), which is equivalent to 36% of the total annual mass change throughout Central Alaska. PMID:23857302

Burgess, Evan W; Forster, Richard R; Larsen, Christopher F

2013-01-01

158

Muir Glacier and Muir Inlet 1980  

USGS Multimedia Gallery

This ship-deck-based August 1980 photograph of Muir Glacier and Muir Inlet, Glacier Bay National Park and Preserve, St. Elias Mountains, Alaska, shows the nearly 200-ft-high retreating tidewater end of Muir Glacier with part of its face capped by a few angular pinnacles of ice, called sracs....

159

Delineation of landform and lithologic units for Ecological Landtype-Association analysis in Glacier Bay National Park, Southeast Alaska  

USGS Publications Warehouse

In this study, landforms were classified-by using topographic maps and personal experience-into eight categories similar to those used by the U.S. Forest Service. The 90 bedrock-lithologic units on the current Glacier Bay geologic map were classified into 13 generalized lithologic units corresponding exactly to those used by the U.S. Forest Service. Incomplete storm-track, storm-intensity, and limited climatic information have also been compiled.

Brew, David A.

2008-01-01

160

Alaska  

USGS Publications Warehouse

Alaska is the United States' only Arctic region. Its marine, tundra, boreal (northern) forest, and rainforest ecosystems differ from most of those in other states and are relatively intact. Alaska is home to millions of migratory birds, hundred of thousands of caribou, some of the nation's largest salmon runs, a significant proportion of he nation's marine mammals, and half of the nation's fish catch. Energy production is the main driver of the state's economy, providing more than 80% of state government revenue and thousands of jobs. Continuing pressure for oil, gas, and mineral development on land and offshore in ice-covered waters increases the demand for infrastructure, placing additional stresses on ecosystems. Land-based energy exploration will be affected by a shorter season when ice roads are viable, yet reduced sea ice extent may create more opportunity for offshore development. Climate also affects hydropower generation. Mining and fishing are the second and third largest industries in the state, with tourism rapidly increasing the 1990s. Fisheries are vulnerable to changes in fish abundance and distribution that result from both climate change and fishing pressure. Tourism might respond positively to warmer springs and autumns but negatively to less favorable conditions for winter activities and increased summer smoke from wildfire. Alaska is home to 40% (229 of 566) of the federally recognized tribes in the United States. The small number of jobs, high cost of living, and rapid social change make rural, predominantly Native, communities highly vulnerable to climate change through impacts on tradition hunting and fishing and cultural connection to the land and sad. Because most of these communities re not connected to the state's road system or electrical grid, the cost of living is high, and it is challenging to supply good, fuel, materials, health care, and other services. Climate impacts on these communities are magnified by additional social and economic stresses. However, Alaskan Native communities have for centuries dealt with scarcity and high environmental variability and thus have deep cultural reservoirs of flexibility and adaptability.

Chapin, F. Stuart, III; Trainor, Sarah F.; Cochran, Patricia; Huntington, Henry; Markon, Carl J.; McCammon, Molly; McGuire, A. David; Serreze, Mark

2014-01-01

161

Mass balance, meteorological, ice motion, surface altitude, and runoff data at Gulkana Glacier, Alaska, 1993 balance year  

USGS Publications Warehouse

The 1993 measured winter snow, maximum winter snow, net, and annual balances in the Gulkana Glacier basin were evaluated on the basis of meteorological, hydrological, and glaciological data measured in the basin and are reported herein. Averaged over the glacier, the measured winter snow balance was 0.81 meter on March 31, 1993, 1.2 standard deviations below the long-term average; the maximum winter snow balance, 0.84 meter, was reached on May 10, 1993 and remained until May 11, 1993; the net balance (from August 18, 1992 to September 8, 1993) was 1.80 meters, the most negative balance year on record at 2.8 standard deviations below the long-term average. The annual balance (October 1, 1992 to September 30, 1993) was 1.64 meters. Ice-surface motion and altitude changes measured at three index sites document seasonal ice speed and glacier thickness changes. Annual stream runoff was 1.996 meters averaged over the basin, 0.2 standard deviations above the long-term average.

March, Rod; Trabant, Dennis

1997-01-01

162

Apogean-perigean signals encoded in tidal flats at the fluvio-estuarine transition of Glacier Creek, Turnagain Arm, Alaska; implications for ancient tidal rhythmites  

USGS Publications Warehouse

Turnagain Arm is a macrotidal fjord-style estuary. Glacier Creek is a small, glacially fed stream which enters the estuary tangentially near Girdwood, Alaska. Trenches and daily sedimentation measurements were made in a mudflat along the fluvio-estuarine transition of Glacier Creek during several summers since 2003. Each year, the flats appear to erode during the winter and then accrete vertically in the spring and summer. In each of the years studied, tidal laminae in vertically thickening and thinning laminae bundles were deposited by twice daily tides in neap-spring tidal cycles. In 2004, bundles of thickening and thinning laminae couplets were noted in trenches cut into the flats. Five laminae bundles alternated between thicker and thinner bundles, corresponding to the perigean (high spring) and apogean (low spring) tides. Well-preserved apogean-perigean cycles have rarely been documented in modern tidal flat sediments. At this location, vertical accretion of tidal rhythmites with well-developed neap-spring cyclicity is possible because of the near-complete removal of the flat from the previous year, which creates accommodation space for vertical accretion without significant reworking. Macrotidal conditions, no reworking by infaunal invertebrates, protection from the main tidal channel by a gravel bar and protection from storm waves and fluvial erosion by a recess in the sedge marsh that surrounds the flats all aid in preservation of rhythmites during aggradation. The position of the flats relative to tidal range allows for accumulation of complete spring cycles and incomplete neap cycles. In the summer of 2004, apogee and perigee were closely aligned with the new and full moons, resulting in successive strong perigee and apogee tides which probably aided in the accumulation of successive thick-thin spring cycles encoding the apogean and perigean tidal cycle. The apogean-perigean signal was not observed in subsequent years. ?? 2011 The Authors.

Greb, S.F.; Archer, A.W.; Deboer, D.G.

2011-01-01

163

The Significance of Shifts in Precipitation Patterns: Modelling the Impacts of Climate Change and Glacier Retreat on Extreme Flood Events in Denali National Park, Alaska  

PubMed Central

In glacier-fed systems climate change may have various effects over a range of time scales, including increasing river discharge, flood frequency and magnitude. This study uses a combination of empirical monitoring and modelling to project the impacts of climate change on the glacial-fed Middle Fork Toklat River, Denali National Park, Alaska. We use a regional calibration of the model HBV to account for a paucity of long term observed flow data, validating a local application using glacial mass balance data and summer flow records. Two Global Climate Models (HADCM3 and CGCM2) and two IPCC scenarios (A2 and B2) are used to ascertain potential changes in meteorological conditions, river discharge, flood frequency and flood magnitude. Using remote sensing methods this study refines existing estimates of glacial recession rates, finding that since 2000, rates have increased from 24m per year to 68.5m per year, with associated increases in ablation zone ice loss. GCM projections indicate that over the 21st century these rates will increase still further, most extensively under the CGCM2 model, and A2 scenarios. Due to greater winter precipitation and ice and snow accumulation, glaciers release increasing meltwater quantities throughout the 21st century. Despite increases in glacial melt, results indicate that it is predominantly precipitation that affects river discharge. Three of the four IPCC scenarios project increases in flood frequency and magnitude, events which were primarily associated with changing precipitation patterns, rather than extreme temperature increases or meltwater release. Results suggest that although increasing temperatures will significantly increase glacial melt and winter baseflow, meltwater alone does not pose a significant flood hazard to the Toklat River catchment. Projected changes in precipitation are the primary concern, both through changing snow volumes available for melt, and more directly through increasing catchment runoff. PMID:24023925

Crossman, Jill; Futter, Martyn N.; Whitehead, Paul G.

2013-01-01

164

Gagiwdul.at: Brought Forth To Reconfirm. The Legacy of a Taku River Tlingit Clan.  

ERIC Educational Resources Information Center

The six legends told here, in Tlingit on the left page and in English on the right page, are told by Elizabeth Nyman, a Tlingit elder of the Taku River clan. The narratives represent a portion of the clan's oral history. Introductory sections provide some historical background concerning the clan, the story teller, and the traditions with which

Nyman, Elizabeth; Leer, Jeff

165

Geochronology of plutonic rocks and their tectonic terranes in Glacier Bay National Park and Preserve, southeast Alaska: Chapter E in Studies by the U.S. Geological Survey in Alaska, 2008-2009  

USGS Publications Warehouse

We have identified six major belts and two nonbelt occurrences of plutonic rocks in Glacier Bay National Park and Preserve and characterized them on the basis of geologic mapping, igneous petrology, geochemistry, and isotopic dating. The six plutonic belts and two other occurrences are, from oldest to youngest: (1) Jurassic (201.6145.5 Ma) diorite and gabbro of the Lituya belt; (2) Late Jurassic (161.0145.5 Ma) leucotonalite in Johns Hopkins Inlet; (3) Early Cretaceous (145.599.6 Ma) granodiorite and tonalite of the Muir-Chichagof belt; (4) Paleocene tonalite in Johns Hopkins Inlet (65.555.8 Ma); (5) Eocene granodiorite of the Sanak-Baranof belt; (6) Eocene and Oligocene (55.823.0 Ma) granodiorite, quartz diorite, and granite of the Muir-Fairweather felsic-intermediate belt; (7) Eocene and Oligocene (55.823.0 Ma) layered gabbros of the Crillon-La Perouse mafic belt; and (8) Oligocene (33.923.0 Ma) quartz monzonite and quartz syenite of the Tkope belt. The rocks are further classified into 17 different combination age-compositional units; some younger belts are superimposed on older ones. Almost all these plutonic rocks are related to Cretaceous and Tertiary subduction events. The six major plutonic belts intrude the three southeast Alaska geographic subregions in Glacier Bay National Park and Preserve, from west to east: (1) the Coastal Islands, (2) the Tarr Inlet Suture Zone (which contains the Border Ranges Fault Zone), and (3) the Central Alexander Archipelago. Each subregion includes rocks assigned to one or more tectonic terranes. The various plutonic belts intrude different terranes in different subregions. In general, the Early Cretaceous plutons intrude rocks of the Alexander and Wrangellia terranes in the Central Alexander Archipelago subregion, and the Paleogene plutons intrude rocks of the Chugach, Alexander, and Wrangellia terranes in the Coastal Islands, Tarr Inlet Suture Zone, and Central Alexander Archipelago subregions.

Brew, David A.; Tellier, Kathleen E.; Lanphere, Marvin A.; Nielsen, Diane C.; Smith, James G.; Sonnevil, Ronald A.

2014-01-01

166

Black and Brown Bear Activity at Selected Coastal Sites in Glacier Bay National Park and Preserve, Alaska: A Preliminary Assessment Using Noninvasive Procedures  

USGS Publications Warehouse

A number of efforts in recent years have sought to predict bear activity in various habitats to minimize human disturbance and bear/human conflicts. Alaskan coastal areas provide important foraging areas for bears (Ursus americanus and U. arctos), particularly following den emergence when there may be no snow-free foraging alternatives. Additionally, coastal areas provide important food items for bears throughout the year. Glacier Bay National Park and Preserve (GLBA) in southeastern Alaska has extensive coastal habitats, and the National Park Service (NPS) has been long interested in learning more about the use of these coastal habitats by bears because these same habitats receive extensive human use by park visitors, especially kayaking recreationists. This study provides insight regarding the nature and intensity of bear activity at selected coastal sites within GLBA. We achieved a clearer understanding of bear/habitat relationships within GLBA by analyzing bear activity data collected with remote cameras, bear sign mapping, scat collections, and genetic analysis of bear hair. Although we could not quantify actual levels of bear activity at study sites, agreement among measures of activity (for example, sign counts, DNA analysis, and video record) lends support to our qualitative site assessments. This work suggests that habitat evaluation, bear sign mapping, and periodic scat counts can provide a useful index of bear activity for sites of interest.

Partridge, Steve; Smith, Tom; Lewis, Tania

2009-01-01

167

Marine benthic habitat mapping of Muir Inlet, Glacier Bay National Park and Preserve, Alaska, with an evaluation of the Coastal and Marine Ecological Classification Standard III  

USGS Publications Warehouse

Seafloor geology and potential benthic habitats were mapped in Muir Inlet, Glacier Bay National Park and Preserve, Alaska, using multibeam sonar, ground-truth information, and geological interpretations. Muir Inlet is a recently deglaciated fjord that is under the influence of glacial and paraglacial marine processes. High glacially derived sediment and meltwater fluxes, slope instabilities, and variable bathymetry result in a highly dynamic estuarine environment and benthic ecosystem. We characterize the fjord seafloor and potential benthic habitats using the Coastal and Marine Ecological Classification Standard (CMECS) recently developed by the National Oceanic and Atmospheric Administration (NOAA) and NatureServe. Substrates within Muir Inlet are dominated by mud, derived from the high glacial debris flux. Water-column characteristics are derived from a combination of conductivity temperature depth (CTD) measurements and circulation-model results. We also present modern glaciomarine sediment accumulation data from quantitative differential bathymetry. These data show Muir Inlet is divided into two contrasting environments: a dynamic upper fjord and a relatively static lower fjord. The accompanying maps represent the first publicly available high-resolution bathymetric surveys of Muir Inlet. The results of these analyses serve as a test of the CMECS and as a baseline for continued mapping and correlations among seafloor substrate, benthic habitats, and glaciomarine processes.

Trusel, Luke D.; Cochrane, Guy R.; Etherington, Lisa L.; Powell, Ross D.; Mayer, Larry A.

2010-01-01

168

The length of the glaciers in the world - a straightforward method for the automated calculation of glacier center lines  

NASA Astrophysics Data System (ADS)

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.

Machguth, H.; Huss, M.

2014-05-01

169

Seasonal variabilty of surface velocities and ice discharge of Columbia Glacier, Alaska using high-resolution TanDEM-X satellite time series and NASA IceBridge data  

NASA Astrophysics Data System (ADS)

Columbia Glacier is a grounded tidewater glacier located on the south coast of Alaska. It has lost half of its volume during 1957-2007, more rapidly after 1980. It is now split into two branches, known as Main/East and West branch due to the dramatic retreat of ~ 23 km and calving of iceberg from its terminus in past few decades. In Alaska, a majority of the mass loss from glaciers is due to rapid ice flow and calving icebergs into tidewater and lacustrine environments. In addition, submarine melting and change in the frontal position can accelerate the ice flow and calving rate. We use time series of high-resolution TanDEM-X stripmap satellite imagery during 2011-2013. The active image of the bistatic TanDEM-X acquisitions, acquired over 11 or 22 day repeat intervals, are utilized to derive surface velocity fields using SAR intensity offset tracking. Due to the short temporal baselines, the precise orbit control and the high-resolution of the data, the accuracies of the velocity products are high. We observe a pronounce seasonal signal in flow velocities close to the glacier front of East/Main branch of Columbia Glacier. Maximum values at the glacier front reach up to 14 m/day were recorded in May 2012 and 12 m/day in June 2013. Minimum velocities at the glacier front are generally observed in September and October with lowest values below 2 m/day in October 2012. Months in between those dates show corresponding increase or deceleration resulting a kind of sinusoidal annual course of the surface velocity at the glacier front. The seasonal signal is consistently decreasing with the distance from the glacier front. At a distance of 17.5 km from the ice front, velocities are reduced to 2 m/day and almost no seasonal variability can be observed. We attribute these temporal and spatial variability to changes in the basal hydrology and lubrification of the glacier bed. Closure of the basal drainage system in early winter leads to maximum speeds while during a fully developed basal drainage system speeds are at their minimum. We also analyze the variation in conjunction with the prevailing meteorological conditions as well as changes in calving front position in order to exclude other potential influencing factors. In a second step, we also exploit TanDEM-X data to generate various digital elevation models (DEMs) at different time steps. The multi-temporal DEMs are used to estimate the difference in surface elevation and respective ice thickness changes. All TanDEM-X DEMs are well tied with a SPOT reference DEM. Errors are estimated over ice free moraines and rocky areas. The quality of the TanDEM-X DEMs on snow and ice covered areas are further assessed by a comparison to laser scanning data from NASA Icebridge campaigns. The time wise closest TanDEM-X DEMs were compared to the Icebridge tracks from winter and summer surveys in order to judge errors resulting from the radar penetration of the x/band radar signal into snow, ice and firn. The average differences between laser scanning and TanDEM-X in August, 2011 and March, 2012 are observed to be 8.48 m and 14.35 m respectively. Retreat rates of the glacier front are derived manually by digitizing the terminus position. By combining the data sets of ice velocity, ice thickness and the retreat rates at different time steps, we estimate the seasonal variability of the ice discharge of Columbia Glacier.

Vijay, Saurabh; Braun, Matthias

2014-05-01

170

Benchmark Glaciers  

NSDL National Science Digital Library

The United States Geological Survey (USGS) operates a long-term "benchmark" glacier program to intensively monitor climate, glacier motion, glacier mass balance, glacier geometry, and stream runoff at a few select sites. The data collected are used to understand glacier-related hydrologic processes and improve the quantitative prediction of water resources, glacier-related hazards, and the consequences of climate change. This page presents some of the balance, runoff, and temperature data for three glaciers: Gulkana, South Cascade and Wolverine. Reports for each of these glaciers uses the collected data to draw many conclusions. There is also a section with common questions and myths about glaciers.

171

Bivachnyy Glacier  

USGS Multimedia Gallery

Photograph of Bivachnyy Glacier, a surging valley glacier in the central Pamir Mountains. The glacier has a thick debris cover derived from adjacent mountains. Photograph courtesy of V.M. Kotlyakov, Russian Academy of Sciences, Moscow....

172

Glacier Melt  

NSDL National Science Digital Library

This short video shows an example of melting alpine glaciers in the Austrian Alps (Goldberg Glacier). Disappearing alpine glaciers have social and environmental impacts, including the decline of fresh water supplies and contributing to sea level rise.

National Geographic

173

Deglaciation and latest Pleistocene and early Holocene glacier readvances on the Alaska Peninsula: Records of rapid climate change due to transient changes in solar intensity and atmospheric CO sub 2 content  

SciTech Connect

Geologic mapping near Windy Creek, Katmai National Park, identified two sets of glacial deposits postdating late-Wisconsin Iliuk moraines and separated from them by volcaniclastic deposits laid down under ice-free conditions. Radiocarbon dating of organic material incorporated in the younger Katolinat till and in adjacent peat and lake sediments suggests that alpine glaciers on the northern Alaska Peninsula briefly expanded between ca. 8500 and 10,000 years B.P. Stratigraphic relationships and radiocarbon dates suggest an age for the older Ukak drift near the Pleistocene-Holocene boundary between ca. 10,000 and 12,000 years B.P. The authors suggest that rapid deglaciation following deposition of the Iliuk drift occurred ca. 13,000-12,000 years B.P. in response to large increases in global atmospheric greenhouse gas content, including C02. Short-term decreases in these concentrations, as recorded in polar ice cores, may be linked with brief periods of glacier expansion during the latest Pleistocene and early Holocene. A transient episode of low solar intensity may also have occurred during parts of the early Holocene. Rapid environmental changes and glacial fluctuations on the Alaska Peninsula may have been in response to transient changes in the concentration of atmospheric greenhouse gases and solar intensity.

Pinney, D.S.; Beget, J.E.

1992-03-01

174

Toward tracking glacier ice-balance with seismology Y a h t s e g l a c i e r , A l a s k a  

E-print Network

Toward tracking glacier ice-balance with seismology Y a h t s e g l a c i e r , A l a s k a Michael West, mewest@alaska.edu Geophysical Institute, Univ. Alaska Fairbanks Glaciers generate extremely by iceberg calving at the terminus of tidewater glaciers. A recent surge in glacier

West, Michael

175

Chemical weathering in the foreland of a retreating glacier  

Microsoft Academic Search

Chemical denudation rates and strontium isotope ratios in streams vary substantially and systematically in the foreland of the retreating Bench Glacier in south-central Alaska. To study weathering of young glacier sediments, we sampled 12 streams draining a chronosequence of till and moraine soils derived from Cretaceous metagraywacke-metapelite bedrock. Both sediment age and vegetation cover increase with distance from the glacier.

Suzanne Prestrud Anderson; James I. Drever; Carol D. Frost; Pete Holden

2000-01-01

176

Chemical weathering in the foreland of a retreating glacier  

Microsoft Academic Search

Chemical denudation rates and strontium isotope ratios in streams vary substantially and systematically in the foreland of the retreating Bench Glacier in south-central Alaska. To study weathering of young glacier sediments, we sampled 12 streams draining a chronosequence of till and moraine soils derived from Cretaceous metagraywackemetapelite bedrock. Both sediment age and vegetation cover increase with distance from the glacier.

Suzanne Prestrud Anderson; James I Drever; Carol D Frost; Pete Holden

2000-01-01

177

Glacier Maker  

NSDL National Science Digital Library

This site contains hands-on activities that explore the structure of glaciers. Students identify the contents of a glacier like those found in Patagonia; construct a mini glacier model in class; and compare and contrast the classroom model with Patagonian glaciers. Topics included in this page are: Instructional objectives, background materials, activity, procedure, evaluation and web resources.

178

Alexander Archipelago, Southeastern Alaska  

NASA Technical Reports Server (NTRS)

West of British Columbia, Canada, and south of the Yukon Territory, the southeastern coastline of Alaska trails off into the islands of the Alexander Archipelago. The area is rugged and contains many long, U-shaped, glaciated valleys, many of which terminate at tidewater. The Alexander Archipelago is home to Glacier Bay National Park. The large bay that has two forks on its northern end is Glacier Bay itself. The eastern fork is Muir inlet, into which runs the Muir glacier, named for the famous Scottish-born naturalist John Muir. Glacier Bay opens up into the Icy Strait. The large, solid white area to the west is Brady Icefield, which terminates at the southern end in Brady's Glacier. To locate more interesting features from Glacier Bay National Park, take a look at the park service map. As recently as two hundred years ago, a massive ice field extended into Icy Strait and filled the Glacier Bay. Since that time, the area has experienced rapid deglaciation, with many large glaciers retreating 40, 60, even 80 km. While temperatures have increased in the region, it is still unclear whether the rapid recession is part of the natural cycle of tidewater glaciers or is an indicator of longer-term climate change. For more on Glacier Bay and climate change, read an online paper by Dr. Dorothy Hall, a MODIS Associate Science Team Member. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

2002-01-01

179

The length of the world's glaciers - a new approach for the global calculation of center lines  

NASA Astrophysics Data System (ADS)

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.

Machguth, H.; Huss, M.

2014-09-01

180

Alaska: A frontier divided  

SciTech Connect

The superlatives surrounding Alaska are legion. Within the borders of the 49th US state are some of the world's greatest concentrations of waterfowl, bald eagles, fur seals, walrus, sea lions, otters, and the famous Kodiak brown bear. Alaska features the highest peak of North America, the 20,320-foot Mount McKinley, and the longest archipelago of small islands, the Aleutians. The state holds the greatest percentage of protected wilderness per capita in the world. The expanse of some Alaskan glaciers dwarfs entire countries. Like the periodic advance and retreat of its glaciers, Alaska appears with some regularity on the national US agenda. It last achieved prominence when President Jimmy Carter signed the Alaska National Interest Lands Conservation Act in 1980. Since then the conflict between environmental protection and economic development has been played out throughout the state, and Congress is expected to turn to Alaskan issues again in its next sessions.

O'Dell, R. (Conservation Foundation Latter, Washington, DC (USA))

1986-09-01

181

Operation IceBridge Alaska  

NASA Astrophysics Data System (ADS)

Alaskan and adjoining Canadian glaciers represent the largest area of ice cover outside of the polar regions. Since 1993, the University of Alaska (UAF) has performed light aircraft laser altimetry surveys of over 200 glaciers across the region. Analysis of these survey data led to the discovery that glaciers here are losing mass so rapidly that they contribute significantly to global sea level rise, roughly at the same rate as the entire Greenland icesheet (Arendt et. al, 2002). A recent GRACE study (Wu et al., 2010) has shown that Alaska and Greenland continue to equally dominate the global contribution to non-steric sea level rise. Many of the ice masses in Alaska and adjoining Canada are experiencing an ongoing acceleration in mass wastage (Arendt et. al, 2002; Luthcke et. al, 2008; Larsen et. al, 2008). Operation IceBridge Alaska has continued to collect LiDAR measurements of surface elevation over Alaskan glaciers with the UAF program of light aircraft altimetry. This project has built upon Operation IceBridge flights in 2009 and also upon the previous 18 years of UAF flightlines. During 2009 we began an expansion of the existing UAF program to provide additional data coverage between ICESat I and ICESat II, and due to dynamic and accelerating changes occurring across many southeast and south-central Gulf of Alaska coastal glaciers. The targeted glaciers and icefields have been identified as exceptionally dynamic areas of rapid wastage using recent altimetry, GRACE and ICESat studies. These targeted glaciers are predominately coastal and calving glaciers. The combination of prodigious precipitation, high mass exchange rates, and dynamic effects enables these glaciers to produce a large percentage of Alaskas total contribution to sea level rise. The main questions and goals we are working on include: 1) Is glacier wastage accelerating in northwest North America?, 2) What is Alaskas contribution to global sea level rise?, 3) What areas are experiencing or are about to experience dynamically driven collapse and retreat?, 4) Provide baseline data to validate and enhance GRACE studies of regional mass loss, 5) Acquire laser altimetry data on Alaskan glaciers between ICESat missions I and II. This abstract was written from a remote base of operations during our August field campaign collecting LiDAR data; analysis and results of these data will be presented within the context of our earlier data and results.

Larsen, C. F.; Johnson, A.; Zirnheld, S. L.; Claus, P.

2010-12-01

182

Water Resources of Alaska  

NSDL National Science Digital Library

The Water Resources of Alaska homepage is provided by the US Geological Survey. The goal of this project is to study and understand Alaska's hydrology (surface water, ground water, and water quality) for use and management of the nation's water resources. The site features a list of published reports and information about current projects as well as a vast amount of hydrologic data such as surface water, ground water, water quality, glaciers, water use, and hydrologic data reports.

Geological Survey (U.S.). Water Resources Division. Alaska District.

1999-01-01

183

Glacier Physics  

NSDL National Science Digital Library

This site features a collection of visual resources about glaciers. Diagrams, images and animations reveal how a glacier forms, advances and retreats. These resources can be integrated into lectures, labs or other activities.

Francek, Mark

184

Glacier Webquest  

NSDL National Science Digital Library

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 ...

Mr. Kio

2008-11-06

185

Agassiz Glacier Glacier National Park, MT  

E-print Network

Agassiz Glacier Glacier National Park, MT Greg Pederson photo USGS USGS Repeat Photography Project Glacier Glacier National Park, MT Greg Pederson photo USGS USGS Repeat Photography Project http://nrmsc.usgs.gov/repeatphoto/ 2005 M. V. Walker photo courtesy of GNP archives1943 #12;Blackfoot ­ Jackson Glacier Glacier National

186

International Symposium on Fast Glacier Flow  

NASA Technical Reports Server (NTRS)

Cryospheric Sciences Program "International Symposium on Fast Glacier Flow" (PI, C. Lingle) provided partial support for publication of Annals of Glaciology 36 by the International Glaciological Society. Annals of Glaciology is a peer-reviewed journal. Annals 36, which was published in 2003, contains 39 peer-reviewed and edited papers from the International Symposium on Fast Glacier Flow, which was held in Yakutat, Alaska, 10-14 June 2002.

Lingle, Craig S.

1990-01-01

187

36 CFR 13.1109 - Off-road vehicle use in Glacier Bay National Preserve.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Off-road vehicle use in Glacier Bay National Preserve. 13.1109 ...UNITS IN ALASKA Special Regulations-Glacier Bay National Park and Preserve Administrative...13.1109 Off-road vehicle use in Glacier Bay National Preserve. The use...

2010-07-01

188

36 CFR 13.1116 - Do I need a camping permit in Glacier Bay?  

Code of Federal Regulations, 2010 CFR

... false Do I need a camping permit in Glacier Bay? 13.1116 Section 13.1116...UNITS IN ALASKA Special Regulations-Glacier Bay National Park and Preserve General...1116 Do I need a camping permit in Glacier Bay? From May 1 through September...

2010-07-01

189

36 CFR 13.1150 - Is a permit required for a vessel in Glacier Bay?  

Code of Federal Regulations, 2012 CFR

... Is a permit required for a vessel in Glacier Bay? 13.1150 Section 13.1150...UNITS IN ALASKA Special Regulations-Glacier Bay National Park and Preserve Vessel... Is a permit required for a vessel in Glacier Bay? A permit from the...

2012-07-01

190

36 CFR 13.1150 - Is a permit required for a vessel in Glacier Bay?  

Code of Federal Regulations, 2010 CFR

... Is a permit required for a vessel in Glacier Bay? 13.1150 Section 13.1150...UNITS IN ALASKA Special Regulations-Glacier Bay National Park and Preserve Vessel... Is a permit required for a vessel in Glacier Bay? A permit from the...

2010-07-01

191

36 CFR 13.1109 - Off-road vehicle use in Glacier Bay National Preserve.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 false Off-road vehicle use in Glacier Bay National Preserve. 13.1109 ...UNITS IN ALASKA Special Regulations-Glacier Bay National Park and Preserve Administrative...13.1109 Off-road vehicle use in Glacier Bay National Preserve. The use...

2012-07-01

192

36 CFR 13.1109 - Off-road vehicle use in Glacier Bay National Preserve.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 false Off-road vehicle use in Glacier Bay National Preserve. 13.1109 ...UNITS IN ALASKA Special Regulations-Glacier Bay National Park and Preserve Administrative...13.1109 Off-road vehicle use in Glacier Bay National Preserve. The use...

2014-07-01

193

36 CFR 13.1116 - Do I need a camping permit in Glacier Bay?  

Code of Federal Regulations, 2014 CFR

... false Do I need a camping permit in Glacier Bay? 13.1116 Section 13.1116...UNITS IN ALASKA Special Regulations-Glacier Bay National Park and Preserve General...1116 Do I need a camping permit in Glacier Bay? From May 1 through September...

2014-07-01

194

Monitoring glacier surface seismicity in time and space using Rayleigh waves  

E-print Network

Monitoring glacier surface seismicity in time and space using Rayleigh waves T. D. Mikesell,1,2 K 2011; revised 24 February 2012; accepted 22 March 2012; published 10 May 2012. [1] Sliding glaciers located on Bench Glacier, Alaska (USA) (61.033 N, 145.687 W). We focus on the arrival-time and amplitude

Marshall, Hans-Peter

195

36 CFR 13.1150 - Is a permit required for a vessel in Glacier Bay?  

Code of Federal Regulations, 2013 CFR

... Is a permit required for a vessel in Glacier Bay? 13.1150 Section 13.1150...UNITS IN ALASKA Special Regulations-Glacier Bay National Park and Preserve Vessel... Is a permit required for a vessel in Glacier Bay? A permit from the...

2013-07-01

196

36 CFR 13.1116 - Do I need a camping permit in Glacier Bay?  

Code of Federal Regulations, 2013 CFR

... false Do I need a camping permit in Glacier Bay? 13.1116 Section 13.1116...UNITS IN ALASKA Special Regulations-Glacier Bay National Park and Preserve General...1116 Do I need a camping permit in Glacier Bay? From May 1 through September...

2013-07-01

197

36 CFR 13.1150 - Is a permit required for a vessel in Glacier Bay?  

Code of Federal Regulations, 2014 CFR

... Is a permit required for a vessel in Glacier Bay? 13.1150 Section 13.1150...UNITS IN ALASKA Special Regulations-Glacier Bay National Park and Preserve Vessel... Is a permit required for a vessel in Glacier Bay? A permit from the...

2014-07-01

198

36 CFR 13.1150 - Is a permit required for a vessel in Glacier Bay?  

Code of Federal Regulations, 2011 CFR

... Is a permit required for a vessel in Glacier Bay? 13.1150 Section 13.1150...UNITS IN ALASKA Special Regulations-Glacier Bay National Park and Preserve Vessel... Is a permit required for a vessel in Glacier Bay? A permit from the...

2011-07-01

199

36 CFR 13.1109 - Off-road vehicle use in Glacier Bay National Preserve.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Off-road vehicle use in Glacier Bay National Preserve. 13.1109 ...UNITS IN ALASKA Special Regulations-Glacier Bay National Park and Preserve Administrative...13.1109 Off-road vehicle use in Glacier Bay National Preserve. The use...

2013-07-01

200

36 CFR 13.1109 - Off-road vehicle use in Glacier Bay National Preserve.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 false Off-road vehicle use in Glacier Bay National Preserve. 13.1109 ...UNITS IN ALASKA Special Regulations-Glacier Bay National Park and Preserve Administrative...13.1109 Off-road vehicle use in Glacier Bay National Preserve. The use...

2011-07-01

201

Fastest Glacier  

NSDL National Science Digital Library

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.

NOVA scienceNOW

202

World Glacier Monitoring Service  

NSDL National Science Digital Library

The World Glacier Monitoring Service site contains online issues of Fluctuations of Glaciers and the Glacier Mass Balance Bulletin; glacier inventory data describing the spatial variability and glacier fluctuation data documenting changes in time; explanations of glacier monitoring strategy using glacier mass balance, length change, inventories, and data analysis; and a bibliography of related work.

203

Abundant, seasonally variable supply of glacier flour-derived iron drives high nitrate consumption in Copper River plume and adjacent Gulf of Alaska continental shelf  

Microsoft Academic Search

Recent work has suggested that high iron supply may contribute to a northward increase in phytoplankton biomass along the U.S. west coast, consistent with ``bottom-up'' control of these coastal ecosystems. We examine this hypothesis in waters of the Copper River plume and nearby continental shelf in the northern Gulf of Alaska (GoA). These are the first data we know of

J. Crusius; A. W. Schroth; R. W. Campbell; J. L. Nielsen; I. R. Hoyer; W. Brooks

2010-01-01

204

Seasonal variability of organic matter composition in an Alaskan glacier outflow: insights into glacier carbon sources  

NASA Astrophysics Data System (ADS)

Glacier ecosystems are a significant source of bioavailable, yet ancient dissolved organic carbon (DOC). Characterizing DOC in Mendenhall Glacier outflow (southeast Alaska) we document a seasonal persistence to the radiocarbon-depleted signature of DOC, highlighting ancient DOC as a ubiquitous feature of glacier outflow. We observed no systematic depletion in ? 14C-DOC with increasing discharge during the melt season that would suggest mobilization of an aged subglacial carbon store. However, DOC concentration, ? 13C-DOC, ? 14C-DOC and fluorescence signatures appear to have been influenced by runoff from vegetated hillslopes above the glacier during onset and senescence of melt. In the peak glacier melt period, the ? 14C-DOC of stream samples at the outflow (-181.7 to -355.3) was comparable to the ? 14C-DOC for snow samples from the accumulation zone (-207.2 to -390.9), suggesting that ancient DOC from the glacier surface is exported in glacier runoff. The pre-aged DOC in glacier snow and runoff is consistent with contributions from fossil fuel combustion sources similar to those documented previously in ice cores and thus provides evidence for anthropogenic perturbation of the carbon cycle. Overall, our results emphasize the need to further characterize DOC inputs to glacier ecosystems, particularly in light of predicted changes in glacier mass and runoff in the coming century.

Spencer, Robert G. M.; Vermilyea, Andrew; Fellman, Jason; Raymond, Peter; Stubbins, Aron; Scott, Durelle; Hood, Eran

2014-05-01

205

Title: Climate-glacier Relationship of Retreating Alaskan Glaciers Author: Elliott Mazur and Umesh K. Haritashya  

NASA Astrophysics Data System (ADS)

Portage, Whittier, Eklutna, as well as many other well-known "tourism glaciers" in the vicinity of Anchorage, Alaska are known to have retreated in the past 20 years. This begs the question, "what of the other lesser-known glaciers? Do they follow the same patterns and minimal glacier models?" Glaciers such as Byron, Leonard, Matanuska, Raven and Spencer may fit a minimal model. Information on Byron and Leonard is sparse, as both have become hanging glaciers. Other glaciers, such as Raven, are small enough to be deemed insignificant, yet may have information to give. Consequently our objective is to study five Alaskan glaciers and determine wide-ranging variability to changing regional climate. To do this we obtained field geo-location data and characterized glaciers based on the satellite imagery and climate reevaluation. Our result shows that glaciers are retreating and thinning irrespective of their aspects, location and altitudinal variability. Moreover, our presentation establishes the strong climate-glacier relationship and defines retreating snowline patterns over the last few decades.

Mazur, E. M.

2012-12-01

206

Flow instabilities of Alaskan glaciers  

NASA Astrophysics Data System (ADS)

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.

Turrin, James Bradley

207

Western Glacier Stonefly  

USGS Multimedia Gallery

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 climatewarming. ...

208

Western Glacier Stonefly  

USGS Multimedia Gallery

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 climatewarming. ...

209

Alaska Science Center: Biological Science Office  

NSDL National Science Digital Library

This United States Geological Survey (USGS) site provides summaries of biology projects in Alaska. Topics include ecosystems and habitats (Valdez oil spill, Glacier Bay National Park, coastal habitats, terrestrial habitats), birds, mammals (brown bears, caribou, polar bears, sea otters, wolves, and walrus), fisheries, as well as current and emerging issues in Alaska. This branch of the USGS is responsible for research of trust lands and waters in Alaska, and providing scientific information essential for resource management decisions.

210

Glacier Caves  

NSDL National Science Digital Library

Created by Charlie Anderson Jr. of the International Glaciospeleological Survey, Glacier Caves provides numerous fantastic photographs of glaciers, caves, and volcanoes located mainly in Northwestern United States. Visitors can sort through the images by topic or by location. Users can find various materials on eruptions, special features, and explorations of many famous Northwestern mountains including Mount St. Helens, Mount Hood, and Mount Rainer. The site features links to volcano web cameras.

211

The Bay in Place of a Glacier.  

ERIC Educational Resources Information Center

The cultural resource specialist at Glacier Bay National Park (Alaska) explains the collaborative efforts of park staff and the Hoonah Tlingit to overcome language and cultural barriers in documenting park place names and clan oral history and traditions. The new park-community relationship, which follows decades of conflict, includes training

Howell, Wayne

1997-01-01

212

Melting Glaciers  

NSDL National Science Digital Library

Due to the potential disastrous consequences to the environment and to numerous societies, scientists, governments, and civilians are concerned with the growing trend of glacial melt. This topic-in-depth explores various geographic regions where this phenomenon has recently been observed. Providing background into the study of glaciology, this report begins with a Web site (1) discussing the unique features of glaciers. The US Army Corps of Engineers offers visitors an insight to glacial properties including their locations, movements, and influences; along with a series educational images. The second site (2) explains the exceptionality of the two hundred sixty six glaciers at Glacier National Park. Through a collection of images, animations, and pictures provided by the National Park Service, users can learn about ice dams, climatic impacts, and the erosive powers of ice and water. The rest of the topic-in-depth discusses findings of glacial melting from around the world. NASA (3) addresses the Artic warming's affects on glacier formations. This Web site provides a few animations displaying ice sheet extent and the cracking of icebergs. On a positive note, visitors can learn how the decrease in glaciers has opened up new habitat for some Artic species. The next Web site (4), also by NASA, discusses the findings of a twenty-five year study of Patagonia's glaciers. Educators and students can discover how NASA utilized the Space Shuttle Endeavor to study the entire 17,200 square kilometer region. The site also discusses potential causes of the melting in this region, which has contributed to almost ten percent of the global sea-level change from mountain glaciers. As reported by the BBC (5), Dr. Harrison at the University of Oxford has determined that the glaciers in parts of Kazakhstan have been decreasing annually by almost two cubic kilometers between 1955 and 2000. Visitors can learn how the melting of these four hundred sixteen glaciers will adversely affect the region's rivers and its water supply. The Taipei Times (6) reports that the Swiss Alpine glacial melting has probably intensified due to this summer's record-breaking heat wave. This Web site provides short, intriguing descriptions of consequences of the "rush of melt water streaming from the ice wall." Users can learn about predictions in the 1990s that the glaciers would shrink to ten percent of their 1850 size by the end of the twenty first century. In the next Web site (7), the BBC provides a captivating illustration of the effects the Peruvian glacial melts may have on tourism, the country's water supply, and more. Students and educators can learn about NASA studies showing cracks in the ice, which could lead to the flooding of large cities. Visitors can also find out how the recent glacier recessions have affected some ancient spiritual traditions. The last site, by the USGS, (8) features excerpts from Myrna Hall and Daniel Fagre's 2003 research paper in BioScience. Visitors can discover the melt rate and spatial distributions of glaciers for two possible future climate situations. Providing an amazing animation, users will be amazed by the changes predicted by the model.

Enright, Rachel

213

Glaciers and Global Climate  

NASA Technical Reports Server (NTRS)

Glaciers are important indicators of global climate. Glacier recession, as observed from space and in the field, has been occurring for about 100 years. The present extent of glaciers and glaciers in the last Ice Age will be discussed. I will show slides of field work on glaciers and show instruments used to measure ice and snow. I will discuss reasons for studying glaciers and why remote sensing is important for glacier studies.

Hall, Dorothy K.

1999-01-01

214

Phase transition in MgSiO3 perovskite in the earth's lower mantle Taku Tsuchiya*, Jun Tsuchiya, Koichiro Umemoto, Renata M. Wentzcovitch  

E-print Network

Phase transition in MgSiO3 perovskite in the earth's lower mantle Taku Tsuchiya*, Jun Tsuchiya-ray diffraction measurements. This transition appears to be associated with the DU discontinuity. D 2004 Elsevier B.V. All rights reserved. Keywords: post-perovskite; MgSiO3; first principle; coremantle boundary

Vocadlo, Lidunka

215

Fast tidewater glaciers  

Microsoft Academic Search

Some iceburg-calving outlet glaciers flow continuously at speeds normally associated with surging glaciers and exhibit dramatic instability scenarios related to those suggested for marine ice sheets. No temperature tidewater glaciers are known to have floating termini, but many polar and subpolar tidewater glaciers do. The fast flow of temperature calving glaciers is almost entirely due to basal sliding and appears

M. F. Meier; Austin Post

1987-01-01

216

Columbia Glacier in 1986; 800 meters retreat  

USGS Publications Warehouse

Columbia Glacier, in Prince William Sound, Alaska, continued its rapid retreat in 1986, with a retreat of 800 m. Average velocity of the lower portion of the glacier, 10 September 1986 to 26 January 1987, was three km/yr, or about one-half of the velocity during similar periods for the previous three years. This reduced velocity is a new development in the progression of the retreat, and if the calving rate follows the pattern of previous years, will result in continued retreat. (Author 's abstract)

Krimmel, R.M.

1987-01-01

217

Assessing streamflow sensitivity to variations in glacier mass balance  

NASA Astrophysics Data System (ADS)

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.

Oneel, S.; Hood, E. W.; Arendt, A. A.; Sass, L. C.; March, R. S.

2013-12-01

218

Glacier Photograph Collection  

NSDL National Science Digital Library

These repeat photographs (also known as glacier pairs) are of special interest to scientists studying glaciers and climate. Glacier photographs taken from the same vantage point, but years apart in time, can reveal dramatic changes in the glacier terminus position, as a glacier either advances or retreats. Most glaciers around the world have retreated at unprecedented rates over the last century. These pairs of photographs can provide striking visual evidence of climate change.

National Snow and Ice Data Center

219

Northeast Glaciers  

NSDL National Science Digital Library

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.

2003-01-01

220

GeoFORCE Alaska, A Successful Summer Exploring Alaska's Geology  

NASA Astrophysics Data System (ADS)

Thirty years old this summer, RAHI, the Rural Alaska Honors Institute is a statewide, six-week, summer college-preparatory bridge program at the University of Alaska Fairbanks for Alaska Native and rural high school juniors and seniors. This summer, in collaboration with the University of Texas Austin, the Rural Alaska Honors Institute launched a new program, GeoFORCE Alaska. This outreach initiative is designed to increase the number and diversity of students pursuing STEM degree programs and entering the future high-tech workforce. It uses Earth science to entice kids to get excited about dinosaurs, volcanoes and earthquakes, and includes physics, chemistry, math, biology and other sciences. Students were recruited from the Alaska's Arctic North Slope schools, in 8th grade to begin the annual program of approximately 8 days, the summer before their 9th grade year and then remain in the program for all four years of high school. They must maintain a B or better grade average and participate in all GeoFORCE events. The culmination is an exciting field event each summer. Over the four-year period, events will include trips to Fairbanks and Anchorage, Arizona, Oregon and the Appalachians. All trips focus on Earth science and include a 100+ page guidebook, with tests every night culminating with a final exam. GeoFORCE Alaska was begun by the University of Alaska Fairbanks in partnership with the University of Texas at Austin, which has had tremendous success with GeoFORCE Texas. GeoFORCE Alaska is managed by UAF's long-standing Rural Alaska Honors Institute, that has been successfully providing intense STEM educational opportunities for Alaskan high school students for over 30 years. The program will add a new cohort of 9th graders each year for the next four years. By the summer of 2015, GeoFORCE Alaska is targeting a capacity of 160 students in grades 9th through 12th. Join us to find out more about this exciting new initiative, which is enticing young Alaska Native and minority students into the geosciences. View them as they explore the permafrost tunnel in Fairbanks, sand dunes in Anchorage, Portage Glacier, Matanuska-Susitna Glacier, and the Trans-Alaska pipeline damage from the earthquake of 2002.

Wartes, D.

2012-12-01

221

Shepard Glacier, Glacier National Park, Montana - 2005  

USGS Multimedia Gallery

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)...

222

Tour of Park Geology: Glaciers and Glacial Landforms  

NSDL National Science Digital Library

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.

223

Muir Glacier Retreats  

USGS Multimedia Gallery

Muir Glacier has retreated out of the field of view and is now nearly 5 miles to the northwest. Riggs Glacier has retreated as much as 2000 ft and thinned by more than 800 feet. Note the dense vegetation that has developed. Also note the correlation between Muir Glaciers 1941 thickness and th...

224

Columbia Bay, Alaska: an 'upside down' estuary  

USGS Publications Warehouse

Circulation and water properties within Columbia Bay, Alaska, are dominated by the effects of Columbia Glacier at the head of the Bay. The basin between the glacier terminus and the terminal moraine (sill depth of about 22 m) responds as an 'upside down' estuary with the subglacial discharge of freshwater entering at the bottom of the basin. The intense vertical mixing caused by the bouyant plume of freshwater creates a homogeneous water mass that exchanges with the far-field water through either a two- or a three-layer flow. In general, the glacier acts as a large heat sink and creates a water mass which is cooler than that in fjords without tidewater glaciers. The predicted retreat of Columbia Glacier would create a 40 km long fjord that has characteristics in common with other fjords in Prince William Sound. ?? 1988.

Walters, R.A.; Josberger, E.G.; Driedger, C.L.

1988-01-01

225

Ice Worms and Their Habitats on North Cascade Glaciers  

NSDL National Science Digital Library

This article describes ice worms (Mesenchytraeus solifugus) that live on glaciers in southern Alaska, the Coastal range and British Columbia, and in the Olympics and North Cascades as far south as Mt. St. Helens. Pictures of the ice worms and information on their habitat, physiolology, diet, and behavior are provided.

Paula Hartzell

226

Glacier inventory of the upper Huasco valley, Norte Chico, Chile: glacier characteristics, glacier change and comparison with  

E-print Network

Glacier inventory of the upper Huasco valley, Norte Chico, Chile: glacier characteristics, glacier Chile, Portugal 84, Casilla 3387, Santiago, Chile ABSTRACT. Results of a new glacier inventory identified, and glaciers with surface areas glacierized area and 3% of the water

Rabatel, Antoine

227

Online Glacier Photograph Database  

NSDL National Science Digital Library

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.

The National Snow and Ice Data Center (NSIDC)

228

Remote sensing of global snowpack energy and mass balance: In-situ measurements on the snow of interior and Arctic Alaska  

NASA Technical Reports Server (NTRS)

This project is continuing along the lines of the semiannual report dated January 1993. Four major tasks have been addressed: analysis of variability in the seasonal snow of interior and arctic Alaska, the interpretation of microwave brightness temperature across Alaska on transects from south to north, study of nonclimatic controls which affect glaciers, and the location of glacier facies boundaries.

Benson, Carl S.

1994-01-01

229

Unusually loud ambient noise in tidewater glacier fjords: a signal of ice melt  

USGS Publications Warehouse

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.

Pettit, Erin C.; Lee, Kevin M.; Brann, Joel P.; Nystuen, Jeffrey A.; Wilson, Preston S.; O'Neel, Shad R.

2015-01-01

230

A century of glacier change in the American West  

NASA Astrophysics Data System (ADS)

Over the past 100 years glaciers in the American West (exclusive of Alaska) have largely receded. The magnitude of the recession varies across the west, with the greatest loss in Montana and California (>50% area loss) and the least loss on the stratovolcanoes (>35%) of the Pacific Northwest. The variations can be broadly characterized by elevation. Our results suggest that increased mass loss caused by increased summer temperatures affect all glaciers, whereas increasing winter temperatures, that change the phase of precipitation from snow to rain adversely affect those glaciers less than 3000m in elevation. The high glaciers (>3000m) of California and Colorado appear to be immune to variations in snowfall making them sensitive to variations in temperature alone. We infer that these very small, steep glaciers can only hold a given amount of snow beyond which extra snow avalanches or is blown off. Conversely, during winters of little direct snowfall, additional snow may be added through win drift from the surrounding terrain. The relatively little glacier shrinkage on the stratovolcanoes is due to the high altitude of the glacier accumulation zones. An east to west decrease in glacier shrinkage from Montana through Washington is due to enhanced winter precipitation along the west coast that somewhat buffers ice loss due to summer temperatures and winter precipitation phase changes.

Fountain, A. G.

2007-12-01

231

Observations and analysis of self-similar branching topology in glacier networks  

USGS Publications Warehouse

Glaciers, like rivers, have a branching structure which can be characterized by topological trees or networks. Probability distributions of various topological quantities in the networks are shown to satisfy the criterion for self-similarity, a symmetry structure which might be used to simplify future models of glacier dynamics. Two analytical methods of describing river networks, Shreve's random topology model and deterministic self-similar trees, are applied to the six glaciers of south central Alaska studied in this analysis. Self-similar trees capture the topological behavior observed for all of the glaciers, and most of the networks are also reasonably approximated by Shreve's theory. Copyright 1996 by the American Geophysical Union.

Bahr, D.B.; Peckham, S.D.

1996-01-01

232

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

USGS Publications Warehouse

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

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

1979-01-01

233

The Alaska Volcano Observatory (AVO) was established in 1988 to carry out volcano monitoring, eruption notification, and volcanic hazards assessments in Alaska. The cooperating agencies of  

E-print Network

#12;The Alaska Volcano Observatory (AVO) was established in 1988 to carry out volcano monitoring with the Kamchatkan Volcanic Eruptions Response Team (KVERT). Cover photo: Iliamna Volcano and Umbrella Glacier as viewed from the valley of West Glacier Creek. View is toward the northeast. #12;Preliminary Volcano

234

A LARGE ROCK AVALANCHE ONTO MORSRJKULL GLACIER, SOUTH-EAST ICELAND. ITS IMPLICATIONS FOR ICE-SURFACE EVOLUTION  

E-print Network

, mainly from Alaska, United States, the Himalaya and New Zealand. A characteristic of such rock avalanches1 A LARGE ROCK AVALANCHE ONTO MORSRJKULL GLACIER, SOUTH-EAST ICELAND. ITS IMPLICATIONS FOR ICE-SURFACE EVOLUTION AND GLACIER DYNAMICS Armelle Decaulne(1,2) , orsteinn Smundsson(3) , Halldr G. Ptursson(4

Paris-Sud XI, Universit de

235

Afghanistan Glacier Diminution  

Microsoft Academic Search

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

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

2008-01-01

236

Glaciers Then and Now  

NSDL National Science Digital Library

In this activity, students compare 2 photographs (with time span 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.

2007-01-01

237

World Glacier Inventory  

NSDL National Science Digital Library

The National Snow and Ice Data Center (NSIDC) provides the World Glacier Inventory data, which was collected by the World Glacier Monitoring Service. This inventory contains geographic location, area, length, orientation, elevation, and classification of morphological type and moraines of more than 67,000 glaciers throughout the world. The data may be downloaded via FTP or through form-based queries.

238

Glacier (?) National Park  

NSDL National Science Digital Library

Spreadsheets Across the Curriculum/Geology of National Parks module. Students examine data about the disappearing glaciers in the park; after calculating percentage change in the number of glaciers from 1850 to 2000, they interpolate to estimate when Grinnell glacier will be gone.

Module by: Judy McIlrath, University of South Florida Cover Page by: Len Vacher and Denise Davis, University of South Florida

239

The World Glacier Inventory  

NSDL National Science Digital Library

This web site is part of the National Snow and Ice Data Center's World Glacier Monitoring Service. The World Glacier Inventory contains information for over 67,000 glaciers throughout the world. Parameters within the inventory include: geographic location, area, length, orientation, elevation, and classification of morphological type and moraines. The inventory entries are based upon a single observation in time and can be viewed as a "snapshot" of the glacier at this time. These data are collected and digitized by the World Glacier Monitoring Service, Zurich. A point and click map of the world will also take users to the region of interest with a list of glaciated areas.

C. Haggerty

240

Worthington Glacier Project  

NSDL National Science Digital Library

Funded by the National Science Foundation (NSF), the Worthington Glacier Project is a collaboration between researchers at the University of Wyoming and the University of Colorado. The objective of this project is to understand glacier flow dynamics "by comparing detailed measurements of glacier motion with numerical models for glacier flow." Summaries and diagrams are provided of the discussed topics: Borehole Video Observations, Radio-Echo Sounding, Crevassing, Surface Flow Field, Englacial Flow Field, 3-D Flow Field, and In-Situ Stress. Images of the Worthington Glacier fieldwork, future research, and publications are also available at the site.

241

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

SciTech Connect

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.

Sturm, M.; Hall, D.K.; Benson, C.S.; Field, W.O.

1992-03-01

242

Comparative metagenome analysis of an Alaskan glacier.  

PubMed

The temperature in the Arctic region has been increasing in the recent past accompanied by melting of its glaciers. We took a snapshot of the current microbial inhabitation of an Alaskan glacier (which can be considered as one of the simplest possible ecosystems) by using metagenomic sequencing of 16S rRNA recovered from ice/snow samples. Somewhat contrary to our expectations and earlier estimates, a rich and diverse microbial population of more than 2,500 species was revealed including several species of Archaea that has been identified for the first time in the glaciers of the Northern hemisphere. The most prominent bacterial groups found were Proteobacteria, Bacteroidetes, and Firmicutes. Firmicutes were not reported in large numbers in a previously studied Alpine glacier but were dominant in an Antarctic subglacial lake. Representatives of Cyanobacteria, Actinobacteria and Planctomycetes were among the most numerous, likely reflecting the dependence of the ecosystem on the energy obtained through photosynthesis and close links with the microbial community of the soil. Principal component analysis (PCA) of nucleotide word frequency revealed distinct sequence clusters for different taxonomic groups in the Alaskan glacier community and separate clusters for the glacial communities from other regions of the world. Comparative analysis of the community composition and bacterial diversity present in the Byron glacier in Alaska with other environments showed larger overlap with an Arctic soil than with a high Arctic lake, indicating patterns of community exchange and suggesting that these bacteria may play an important role in soil development during glacial retreat. PMID:24712530

Choudhari, Sulbha; Lohia, Ruchi; Grigoriev, Andrey

2014-04-01

243

Alaska volcanoes guidebook for teachers  

USGS Publications Warehouse

Alaskas volcanoes, like its abundant glaciers, charismatic wildlife, and wild expanses inspire and ignite scientific curiosity and generate an ever-growing source of questions for students in Alaska and throughout the world. Alaska is home to more than 140 volcanoes, which have been active over the last 2 million years. About 90 of these volcanoes have been active within the last 10,000 years and more than 50 of these have been active since about 1700. The volcanoes in Alaska make up well over three-quarters of volcanoes in the United States that have erupted in the last 200 years. In fact, Alaskas volcanoes erupt so frequently that it is almost guaranteed that an Alaskan will experience a volcanic eruption in his or her lifetime, and it is likely they will experience more than one. It is hard to imagine a better place for students to explore active volcanism and to understand volcanic hazards, phenomena, and global impacts. Previously developed teachers guidebooks with an emphasis on the volcanoes in Hawaii Volcanoes National Park (Mattox, 1994) and Mount Rainier National Park in the Cascade Range (Driedger and others, 2005) provide place-based resources and activities for use in other volcanic regions in the United States. Along the lines of this tradition, this guidebook serves to provide locally relevant and useful resources and activities for the exploration of numerous and truly unique volcanic landscapes in Alaska. This guidebook provides supplemental teaching materials to be used by Alaskan students who will be inspired to become educated and prepared for inevitable future volcanic activity in Alaska. The lessons and activities in this guidebook are meant to supplement and enhance existing science content already being taught in grade levels 612. Correlations with Alaska State Science Standards and Grade Level Expectations adopted by the Alaska State Department of Education and Early Development (2006) for grades six through eleven are listed at the beginning of each activity. A complete explanation, including the format of the Alaska State Science Standards and Grade Level Expectations, is available at the beginning of each grade link at http://www.eed.state.ak.us/tls/assessment/GLEHome.html.

Adleman, Jennifer N.

2011-01-01

244

Late nineteenth to early twenty-first century behavior of Alaskan glaciers as indicators of changing regional climate  

USGS Publications Warehouse

Alaska's climate is changing and one of the most significant indications of this change has been the late 19th to early 21st century behavior of Alaskan glaciers. Weather station temperature data document that air temperatures throughout Alaska have been increasing for many decades. Since the mid-20th century, the average change is an increase of ?????2.0????C. In order to determine the magnitude and pattern of response of glaciers to this regional climate change, a comprehensive analysis was made of the recent behavior of hundreds of glaciers located in the eleven Alaskan mountain ranges and three island areas that currently support glaciers. Data analyzed included maps, historical observations, thousands of ground-and-aerial photographs and satellite images, and vegetation proxy data. Results were synthesized to determine changes in length and area of individual glaciers. Alaskan ground photography dates from 1883, aerial photography dates from 1926, and satellite photography and imagery dates from the early 1960s. Unfortunately, very few Alaskan glaciers have any mass balance observations. In most areas analyzed, every glacier that descends below an elevation of ?????1500??m is currently thinning and/or retreating. Many glaciers have an uninterrupted history of continuous post-Little-Ice-Age retreat that spans more than 250??years. Others are characterized by multiple late 19th to early 21st century fluctuations. Today, retreating and/or thinning glaciers represent more than 98% of the glaciers examined. However, in the Coast Mountains, St. Elias Mountains, Chugach Mountains, and the Aleutian Range more than a dozen glaciers are currently advancing and thickening. Many currently advancing glaciers are or were formerly tidewater glaciers. Some of these glaciers have been expanding for more than two centuries. This presentation documents the post-Little-Ice-Age behavior and variability of the response of many Alaskan glaciers to changing regional climate. ?? 2006.

Molnia, B.F.

2007-01-01

245

Evaluating glacier melt within a global climate model  

NASA Astrophysics Data System (ADS)

Global climate change has driven drastic changes on ice masses throughout the Earth system. Field studies, remote sensing approaches, and modeling projects have aimed to measure and simulate changes in glaciers, the snowpack, and ice sheets. Recent advances in global climate modeling have greatly improved the representation of the cryosphere and of its changes. While substantial research has been dedicated to the modeling of ice sheets and snow pack, representation for mountain glaciers within global climate models has benefited from relatively fewer studies. This project utilizes the Community Earth System Model (CESM) version 1.2 and examines the performance of a glacier melt modeling scheme. Simulated glacier discharge is studied and compared with in situ data for the Gulkana Glacier in Alaska and larger scale GRACE observations, and put in the context of local hydrology. Specifically, we study the amount of potential infiltration, evaporation, and streamflow that glaciers contribute to the water cycle. Ongoing simulations of future climate are currently being analyzed in order to quantify glacier melt as freshwater supply, and its role in the water budgets of mountainous catchments. Such work will facilitate improved hydrological simulations in the context of expected increased frequency of droughts and dwindling freshwater resources.

Lawrence, C. B.; David, C. H.; Reager, J. T.; Famiglietti, J. S.

2013-12-01

246

Integrated Ground-Based LiDAR and Global Fiducials Program Satellite Imagery Time Series Analysis of the Terminus of Bering Glacier, Alaska During the 2008-2011 Surge  

NASA Astrophysics Data System (ADS)

Satellite imagery from the Global Fiducials Program (GFP: classified satellite imagery released to the general public for science use: http://gfl.usgs.gov) tracked the 2008-2011 surge of the Bering Glacier, the largest and longest glacier in North America. The terminus displacement began in late 2010, with maximum velocities of greater than 20 meters per day by late January 2011, as measured using feature tracking with GFP imagery. By July, the velocities had decreased to less than 10 m/d. We used the GFP imagery to locate three helicopter accessible targets on the terminus of the Bering Glacier to collect high-resolution (0.5-4 cm spot spacing) 4D time-series tripod/terrestrial LiDAR (T-LiDAR) data. During the week of July 24, 2011 we collected hourly and daily T-LiDAR data to resolve spatially and temporally varied advancement rates at each of the sites. The first site was located on the west side of Tashalich arm on the western side of the Bering Lobe terminus proximal to the region where the maximum GFP velocities had previously been measured. Using the T-LiDAR data, we found that the terminus advanced 5.4 m over 76 hours of observation. The hourly advancement rates for the same location are a very consistent 4.2 cm/h during our daylight hours of observation (0900-1800 local) and when daily rate are extrapolated to the full 76 hours, we should have measured 3.2 m of horizontal displacement: this is a discrepancy between the total and hourly measured displacements of an additional 2.2 m of motion during the night and early morning hours (1800-0900 local). The additional motion may be explained by accelerated terminus velocity associated with daily thermal heating and resulting melt. Motion may also be explained by rain on the second day of the survey that "lubricated" the glacier bed thereby allowing it to advance at a faster velocity. The second site was on Arrowhead Island, located on the eastern side of the terminus where the vertical relieve of the glacier terminus was significantly lower than at the fist site that had the elevated velocities. Here the T-LiDAR data measured a much slower advancement rate of 0-2.0 cm/h. The third T-LiDAR site also on Arrowhead Island, approximately 300 meters to the west, measured 7.3 cm/h of motion where the Bering Glacier entered Vitus Lake. We will compare the T-LiDAR and GFP velocities with GPS hourly data collected within the nearby Glacier Ablation Sensor Systems that are deployed on the glacier's surface to assess if the daily variations at the terminus are observed elsewhere during this surge event.

Bawden, G. W.; Molnia, B. F.; Howle, J.; Bond, S.; Angeli, K.; Shuchman, R. A.

2012-12-01

247

Glaciers of Asia  

USGS Publications Warehouse

This chapter is the ninth to be released in U.S. Geological Survey Professional Paper 1386, Satellite Image Atlas of Glaciers of the World, a series of 11 chapters. In each of the geographic area chapters, remotely sensed images, primarily from the Landsat 1, 2, and 3 series of spacecraft, are used to analyze the specific glacierized region of our planet under consideration and to monitor glacier changes. Landsat images, acquired primarily during the middle to late 1970s and early 1980s, were used by an international team of glaciologists and other scientists to study various geographic regions and (or) to discuss related glaciological topics. In each glacierized geographic region, the present areal distribution of glaciers is compared, wherever possible, with historical information about their past extent. The atlas provides an accurate regional inventory of the areal extent of glacier ice on our planet during the 1970s as part of a growing international scientific effort to measure global environmental change on the Earth?s surface. The chapter is divided into seven geographic parts and one topical part: Glaciers of the Former Soviet Union (F-1), Glaciers of China (F-2), Glaciers of Afghanistan (F?3), Glaciers of Pakistan (F-4), Glaciers of India (F-5), Glaciers of Nepal (F?6), Glaciers of Bhutan (F-7), and the Paleoenvironmental Record Preserved in Middle-Latitude, High-Mountain Glaciers (F-8). Each geographic section describes the glacier extent during the 1970s and 1980s, the benchmark time period (1972-1981) of this volume, but has been updated to include more recent information. Glaciers of the Former Soviet Union are located in the Russian Arctic and various mountain ranges of Russia and the Republics of Georgia, Kyrgyzstan, Tajikistan, and Kazakstun. The Glacier Inventory of the USSR and the World Atlas of Ice and Snow Resources recorded a total of 28,881 glaciers covering an area of 78,938 square kilometers (km2). China includes many of the mountain-glacier systems of the world including the Himalaya, Karakorum, Tien Shan and Altay mountain ranges. The glaciers are widely scattered and cover an area of about 59,425 km2. The mountain glaciers may be classified as maritime, subcontinental or extreme continental. In Afghanistan, more than 3,000 small glaciers occur in the Hindu Kush and Pamir mountains. Most glaciers occur on north-facing slopes shaded by mountain peaks and on east and southeast slopes that are shaded by monsoon clouds. The glaciers provide vital water resources to the region and cover an area of about 2,700 km2. Glaciers of northern Pakistan are some of the largest and longest mid-latitude glaciers on Earth. They are located in the Hindu Kush, Himalaya, and Karakoram mountains and cover an area of about 15,000 km2. Glaciers here are important for their role in providing water resources and their hazard potential. The glaciers in India are located in the Himalaya and cover about 8,500 km2. The Himalaya contains one of the largest reservoirs of snow and ice outside the polar regions. The glaciers are a major source of fresh water and supply meltwater to all the rivers in northern India, thereby affecting the quality of life of millions of people. In Nepal, the glaciers are located in the Himalaya as individual glaciers; the glacierized area covers about 5,324 km2. The region is the highest mountainous region on Earth and includes the Mt. Everest region. Glaciers in the Bhutan Himalaya have a total area of about 1,317 km2. Many recent glacier studies are focused on glacier lakes that have the potential of generating dangerous glacier lake outburst floods. Research on the glaciers of the middle-latitude, high-mountain glaciers of Asia has also focused on the information contained in the ice cores from the glaciers. This information helps in the reconstruction of paleoclimatic records, and the computer modeling of global climate change.

Williams, Richard S., Jr.; Ferrigno, Jane G.

2010-01-01

248

Afghanistan Glacier Diminution  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

249

Dynamic behavior of the Bering Glacier-Bagley icefield system during a surge, and other measurements of Alaskan glaciers with ERS SAR imagery  

NASA Technical Reports Server (NTRS)

ERS-1 synthetic aperture radar (SAR) imagery was employed for the measurement of the dynamics of the Bagley icefield during a major surge in 1993-1994, the measurement of ice velocities on the Malaspina piedmont glacier during a quiescent phase between surges, and for mapping the snow lines and the position of the terminus of Nabesna glacier on Mount Wrangell (a 4317 m andesitic shield volcano) in the heavily glacierized Saint Elias and Wrangell Mountains of Alaska. An overview and summary of results is given. The methods used include interferometry, cross-correlation of sequential images, and digitization of boundaries using terrain-corrected SAR imagery.

Lingle, Craig S.; Fatland, Dennis R.; Voronina, Vera A.; Ahlnaes, Kristina; Troshina, Elena N.

1997-01-01

250

DIFFERING CONTRIBUTIONS OF HEAVILY AND MODERATELY GLACIATED BASINS TO WATER RESOURCES OF THE EKLUTNA BASIN, ALASKA  

E-print Network

, U.S. Geological Survey Alaska Science Center, and the National Institutes for Water Resources. Chugach State Park provided access to study sites; Municipal Light and Power-central Alaska, glacier-fed Eklutna Lake contributes freshwater resources for . In 2009 and 2010

Loso, Michael G.

251

All about glaciers  

NSDL National Science Digital Library

The National Snow and Ice Data Center created this website to educate everyone, from grade school students to glaciologists, about glaciers. At the Data and Science link, researchers can learn about glaciological organizations, publications, and research projects as well as how to obtain glacial data. Students and educators can find a glaciology glossary, answers to many of their questions, and amazing images of glaciers at the General Information link. The website also provides a detailed portrayal of the life of glaciers.

252

Glaciers and Climate Change  

Microsoft Academic Search

Although my book focuses on valley glaciers, it is not intended\\u000ato provide a basic course in glaciology, nor does it claim to\\u000agive a state-of-the-art picture of glacier research. It consists\\u000amainly of the personal reflections of a meteorologist who\\u000agradually became interested in glaciers and is written primarily\\u000afor persons with a general interest in the physics of

J. Oerlemans

2001-01-01

253

Glacier Hazards from Space  

NSDL National Science Digital Library

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.

254

Moving Model Glacier  

NSDL National Science Digital Library

In this goopy activity, learners will model glacial movement with gak, a white glue and liquid starch mixture. Each fist-sized gob of gak represents a years worth of snow, accumulating to form a glacier on a model landscape. Learners will record the gaks rate of travel as well as make observations of other glacier behaviors. Relates to the linked video, DragonflyTV GPS: Glaciers.

Twin Cities Public Television, Inc.

2007-01-01

255

Regional projections of glacier volume and runoff in response to twenty-first century climate scenarios (Invited)  

NASA Astrophysics Data System (ADS)

Changes in mass contained by mountain glaciers and ice caps can modify the Earth's hydrological cycle on multiple scales. On a global scale, the mass loss from glaciers contributes to sea level rise. On regional and local scales, glacier melt-water is an important contributor to and modulator of river flow. In this study we use an elevation-dependent glacier mass balance model to project annual volume changes and monthly runoff from all mountain glaciers and ice caps in the world (excluding those in the Antarctic periphery) for the 21st century forced by temperature and precipitation scenarios from 14 global climate models. The largest contributors to projected total volume loss are the glaciers in the Canadian and Russian Arctic, Alaska and glaciers peripheral to Greenland ice sheet. Although small contributors to global volume loss, glaciers in Central Europe, low-latitude South America, Caucasus, North Asia, and Western Canada and US are projected to lose more than 75% of their volume by 2100. The magnitude and sign of trends in annual runoff totals differ considerably among regions depending on the balance between enhanced melt and the reduction of the glacier reservoir by glacier retreat and shrinkage. Most regions show strong declines in glacier runoff indicating that the effect of glacier shrinkage is more dominant than increased melting rates. Some high-latitude regions (Arctic Canada North, Russian Arctic and Greenland) exhibit increases in runoff totals. Iceland and Svalbard show an increase in runoff followed by a multi-decadal decrease in annual runoff.

Radic, V.; Bliss, A. K.; Hock, R.

2013-12-01

256

Glaciers: Teacher's Guide  

NSDL National Science Digital Library

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.

Nichols, Marilyn.

1969-12-31

257

The thermophysics of glaciers  

SciTech Connect

This volume presents the results of experimental and theoretical work on the thermodynamics of ice sheets and glaciers. The author has carried out extensive field work in both the Soviet Union and Antarctica over the last 25 years and has contributed to the understanding of the thermophysics of glaciers. The topics covered in this volume embrace heat flow measurement and temperature distributions in glaciers, the thermal drilling of glaciers, the melting and freezing of ice sheets, and other thermophysical problems. Also included are topics of relevance to glacial engineering.

Zotikov, I.A.

1986-01-01

258

Glaciers and Icebergs  

NSDL National Science Digital Library

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.

Frank Weisel

259

Combination of Geophysical Methods for Measuring the Structure of Rock Glaciers  

NASA Astrophysics Data System (ADS)

The internal structure of talus-derived rock glaciers was surveyed by a combination of electrical resistivity and refraction seismic measurements to study effects of lithological and thermal situations on the development of rock glaciers. P-wave velocity, direct current (DC) resistivity and/or year-round ground surface temperature were measured on 32 rock glaciers in the Alps and 6 rock glaciers in the Brooks Range, Alaska. In the Alps, two lithological situations were compared: one resulted in bouldery rock glaciers covered with matrix-free boulders and the other pebbly rock glaciers consisting of matrix-supported pebbles and cobbles. Different structure accompanying permafrost thawing was studied through the comparison of vegetated rock glaciers with (non- vegetated) bouldery/pebbly rock glaciers, because such vegetated rock glaciers have been regarded as relict in the Alps. In the Brooks Range located in the continuous permafrost area, bouldery rock glaciers are mostly vegetated but probably contain permafrost. The structural difference of rock glaciers between the Alps and much colder and drier Brooks Range is also discussed. In the Alps, subsurface P-wave velocity differed significantly between the bouldery/pebbly rock glaciers (>2 km/s) and the vegetated rock glaciers (<1 km/s). In addition, the bouldery/pebbly rock glaciers had lower surface temperatures than the vegetated rock glaciers. These results indicate the presence of permafrost in the former and the absence in the latter. DC resistivity differed between the bouldery (10-5000 kohmm) and pebbly (0.5-20 kohmm) rock glaciers, whereas the subsurface resistivity had similar values between the pebbly and vegetated types. The bouldery rock glaciers in the Brooks Range lacked high resistivity core (>100 kohmm). Thus, the difference in the resistivity does not reflect the ground temperature (e.g. frozen or unfrozen) but the structural difference (e.g. bouldery or pebbly). In particular, high resistivity values (>100 kohmm) in rock glaciers probably indicate highly ice-supersaturated structure. Such ice-supersaturation in bouldery rock glaciers in the Alps corresponds to the highest potential of snow burial for this type of rock glaciers, having the late-lying thick snow and large rockwalls occasionally providing rock avalanches.

Ikeda, A.

2007-12-01

260

Discriminating glacier thermal and dynamic regimes in the sedimentary record  

NASA Astrophysics Data System (ADS)

This paper provides a description and evaluation of the sedimentary facies and environments associated with a range of glacier thermal and dynamic regimes, with additional consideration given to the tectonic context. New and previously published data are evaluated together, and are presented from modern terrestrial and marine glacial sedimentary environments in order to identify a set of criteria that can be used to discriminate between different glacier thermal regimes and dynamic styles in the sedimentary record. Sedimentological data are presented from a total of 28 glaciers in 11 geographical areas that represent a wide range of contemporary thermal, dynamic and topographic regimes. In the context of "landsystems", representatives from terrestrial environments include temperate glaciers in the European Alps, Patagonia, New Zealand, the Cordillera Blanca (Peru), cold glaciers in the Dry Valleys of Antarctica and the Antarctic Peninsula region, and polythermal valley glaciers in Svalbard, northern Sweden, the Yukon and the Khumbu Himal (Nepal). The glaciomarine environment is illustrated by data from cold and polythermal glacier margins on the East Antarctic continental shelf, and from a polythermal tidewater glacier in Svalbard, along with general observations from temperate glaciers in Alaska. These data show that temperate glacial systems, particularly in high-relief areas, are dominated by rockfall and avalanche processes, although sediments are largely reworked by glaciofluvial processes. Debris in polythermal glaciers is both thermally and topographically influenced. In areas of moderate relief, debris is mainly of basal glacial origin, and the resulting facies association is dominated by diamicton. In high-relief areas such as the Himalaya, the debris load in polythermal glaciers is dominated by rockfall and avalanche inputs, resulting in extensive accumulations of sandy boulder-gravel. Cold glaciers are dominated by basal debris-entrainment, but sediments are little modified from the source materials, which are typically sandy boulder-gravel from older till, and sand (from glaciofluvial, glaciolacustrine and aeolian sources). Similar facies associations, but with different facies geometry and thickness occur in equivalent glaciomarine settings. Application of these concepts can aid the interpretation of glacier thermal regime (and hence palaeoclimate) in Quaternary and ancient glacial systems.

Hambrey, Michael J.; Glasser, Neil F.

2012-04-01

261

Dendrochronology to the Beat of a Different Drummer: Lakes Dammed by a Tidewater Glacier Out of Phase with Climate  

NASA Astrophysics Data System (ADS)

Glacier-dammed lakes typically form during glacier advance or retreat that is in phase with climate change. Most glacier-dammed lakes that have formed in the past century are located in closed basins created by glacier retreat and downwasting. However, tidewater glaciers can be relatively insensitive to climate and can advance when adjacent land-based glaciers are in retreat. The regimen of tidewater glaciers is strongly controlled by the nature of the terminus. When a morainal shoal or fjord constriction limits mass loss due to calving, the glacier may remain stable or advance even in a warming climate. However, a small perturbation in climate can cause the terminus to retreat off a shoal or beyond a constriction into deeper, open water. Once this happens, more mass is lost through calving than is replenished and the glacier may catastrophically retreat. Because many tidewater glaciers are large, this cycle can be several hundred years in length, thereby lagging climatic perturbations that affect other glaciers. Many tidewater glaciers have dammed lakes as they advanced over the past century. Brady Glacier, at the head of Taylor Bay in southeast Alaska, advanced through most of the 20th century. When George Vancouver's party mapped Taylor Bay in 1794, the glacier terminus was a steep calving front. In 1880 John Muir visited the glacier and commented that it was advancing onto an outwash plain that it had built. It continued to advance until the 1960s and has remained at almost the same position since then, despite thinning many tens of meters. As Brady Glacier advanced, it buried trees along the walls of the fjord and impounded large lakes in tributary valleys. At least two of these lakes formed on opposite sides of the glacier in areas occupied by mature forest. We collected incremental cores and discs of trees killed by overriding ice and rising lake waters in order to establish a dendrochronological history of the last glacier advance and the filling of the lakes. The samples are from rooted subfossil trees located at different elevations within the lake basins and below the previous limit of the glacier. The elevation and location of each tree base were determined with a differential GPS. The results show that the Brady was advancing through the area in the early 1800s and that it killed trees along the valley margins at progressively higher levels through time. The oldest and lowest trees that were sampled in the Spur Lake basin on the east side of the glacier were killed in the early 1800s. The lake rose tens of meters over a few decades. The oldest and lowest trees sampled in the North Trick Lake basin on the west side of the glacier were killed in the early 1830s. Like Spur Lake, North Trick Lake increased in depth over a few decades. Many of these trees in both Spur and North Trick lakes were over 300 years old, which indicates that the glacier had been less extensive than today for at least that long. Just to the east, the tidewater glacier in Glacier Bay had advanced about a century earlier than Brady Glacier, underscoring non-climatic controls on glacier activity in the area. As Glacier Bay ice retreated and presumably ice-dammed lakes drained in Glacier Bay, Brady Glacier advanced, damming lakes at its margins. The lakes impounded by Brady Glacier and frequent jkulhlaups derived from them affect glacier motion, mass balance, and glacier stability. The lakes extend beneath portions of the glacier, and significant ice mass is lost to the lakes by calving. Jkulhlaups carve channels into the base of Brady Glacier and could erode the outwash plain at the glacier terminus. Both processes could initiate catastrophic retreat of the glacier.

Capps, D.; Wiles, G.; Clague, J.

2009-04-01

262

Retreat of Glaciers in Glacier National Park In Glacier National Park (GNP), MT some effects of global  

E-print Network

Retreat of Glaciers in Glacier National Park In Glacier National Park (GNP), MT some effects of global climate change are strikingly clear. Glacier recession is underway, and many glaciers have already disappeared. The retreat of these small alpine glaciers reflects changes in recent climate as glaciers respond

263

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

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

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

264

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

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

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

265

Glaciers and Rocks  

NSDL National Science Digital Library

This formative assessment item uncovers students' ideas about glacial erosion and how glaciers transport rocks and other sediment. The assessment is aligned with the National Science Education Standards. It contains instructional suggestions as well as links to other helpful resources dealing with glaciers and glacial movement.

Jessica Fries-Gaither

266

Mini Glacier Meltdown  

NSDL National Science Digital Library

This activity (located on page 3 of the PDF) is a full inquiry investigation about the different causes of glacial melt. Groups of learners will design their own experiment using frozen "glaciers", bricks and different energy sources (fans, and lights) to test how different conditions affect the rate of melting. The results might be surprising. Relates to linked video, DragonflyTV GPS: Glaciers.

Twin Cities Public Television, Inc.

2007-01-01

267

Denali Fault: Susitna Glacier  

USGS Multimedia Gallery

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...

268

Melting Mountain Glaciers  

NSDL National Science Digital Library

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.

NBC Learn

2010-10-07

269

Glacier Peak, Washington  

NSDL National Science Digital Library

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.

270

National Park Glaciers Knowledge Center  

NSDL National Science Digital Library

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.

2005-08-01

271

Modeling Glacier Erosion Through Time  

NSDL National Science Digital Library

Prior to this lab, students will have read and learned about valley glacier processes, glacier mass balance, warm-based and cold-based glaciers, and can identify various glacier landforms formed by erosion. They will also have had an introductory lecture on ice physics, but that is not necessary to complete this activity.

Cathy L Connor

272

On the accuracy of glacier outlines derived from satellite data  

NASA Astrophysics Data System (ADS)

The determination of the accuracy of glacier outlines as mapped from satellite data is a mandatory task, in particular when change assessment is performed. However, this is often not correctly done as a direct comparison with a reference data set can give misleading results. Though it is widely accepted that glacier outlines as derived from a higher-resolution data set (e.g. aerial photography) can be used to determine the accuracy of outlines derived from a lower resolution data set (e.g. Landsat TM), this is not generally true and several details have to be considered. At first, changing glacier extents require to compare images acquired in the same year and rapidly changing snow conditions require to use images from the same week or at least with identical snow conditions (i.e. no snow outside of glaciers). Secondly, differences in interpretation result from the higher-spatial resolution itself and the missing shortwave infrared band in high-resolution data. In particular, the determination of the glacier boundary on panchromatic imagery can locally be impossible (when the ice and the surrounding rock have the same reflectance). Thirdly, for natural objects like glaciers the change of the resolution alone results in a change of the area covered by the respective outline. Finally, the required manual correction of debris-covered glacier parts is done differently by different analysts and also by the same analyst when digitized several times. To overcome these challenges and provide an accuracy assessment for a larger data set, we will perform a combined round robin and validation experiment in the framework of the ESA project Glaciers_cci. This will include the manual and automated digitization of glacier outlines on high and low resolution satellite data (e.g. Quickbird / Ikonos vs. Landsat TM / ETM+) in different parts of the world (Alaska, Alps, Himalaya), as well as multiple digitizations of the same set of glaciers (with and without debris cover) by different and the same analysts. First results indicate that the accuracy of the glacier outlines (clean ice) as derived from automated techniques (TM3/TM5 band ratio) is similar to the standard deviation resulting from multiple digitizing experiments. Regions with low contrast in high-resolution imagery show a large variability in interpretation by different analysts. For an internal accuracy assessment it is recommended to digitize a couple of debris-covered glaciers several times and provide the mean of the standard deviations as the accuracy. An overlay of the digitized outlines is most helpful to identify the problematic regions.

Paul, F.

2012-04-01

273

Using Global Fiducials Program Imagery to Document 50 Years of North American Glacier Change  

NASA Astrophysics Data System (ADS)

As part of the International Geophysical Year (IGY), nine glaciers in Alaska and Washington were imaged and mapped at a 1:10,000 scale by the American Geographical Society (AGS) to: "provide the basis for more satisfactory and more accurate interpretation of the response of these glaciers to meteorological and other factors." Prophetic words indeed. In commemoration of the 50th anniversary of the publication of these maps, the Global Fiducials Program (GFP) systematically re-photographed these glaciers, along with several additional glacier sites, to determine the extent of change at each of these sites. In a new US Geological Survey (USGS) series, maps produced from recently collected GFP imagery, closely following AGS's original map format, are being made for the original nine glaciers. New maps will also be produced for the USGS' three benchmark glaciers and for four new sites--two in California, one in Montana, and one in Nevada. All are either current or proposed GFP sites. Newly acquired and historical imagery will be used to determine changes in terminus position, produce digital elevation models (DEMs), and generate velocity fields from crevasse migration. Where possible, area and volume changes are being determined. Each pair of glacier maps will be accompanied with a summary document describing the changes that have occurred at that glacier. Changes mapped for the Benchmark Glaciers are in agreement with the annual mass balance records compiled by detailed USGS field investigations.

Josberger, E. G.; Fahey, M. J.; Friesen, B. A.; Molnia, B. F.

2012-12-01

274

Associations between accelerated glacier mass wastage and increased summer temperature in coastal regions  

USGS Publications Warehouse

Low-elevation glaciers in coastal regions of Alaska, the Canadian Arctic, individual ice caps around the Greenland ice sheet, and the Patagonia Ice Fields have an aggregate glacier area of about 332 ?? 103 km 2 and account for approximately 42% of all the glacier area outside the Greenland and Antarctic ice sheets. They have shown volume loss, especially since the end of the 1980s, increasing from about 45% in the 1960s to nearly 67% in 2003 of the total wastage from all glaciers on Earth outside those two largest ice sheets. Thus, a disproportionally large contribution of coastal glacier ablation to sea level rise is evident. We examine cumulative standardized departures (1961-2000 reference period) of glacier mass balances and air temperature data in these four coastal regions. Analyses indicate a strong association between increases in glacier volume losses and summer air temperature at regional and global scales. Increases in glacier volume losses in the coastal regions also coincide with an accelerated rate of ice discharge from outlet glaciers draining the Greenland and West Antarctic ice sheets. These processes imply further increases in sea level rise. ?? 2006 Regents of the University of Colorado.

Dyurgerov, M.; McCabe, G.J.

2006-01-01

275

ALASKA MARINE Alaska Marine Mammal Observer Program  

E-print Network

ALASKA MARINE MAMMAL PROGRAM 2012 #12;2012 Alaska Marine Mammal Observer Program Observer Manual Contents Section 1: The Alaska Marine Mammal Observer Program 1.0 Introduction 1.1 Marine Mammal Stock Program 1.5 Alaska Marine Mammal Observer Program Section 2: The Southeast Alaska Environment 2

276

The seismic signature of glacier outburst floods (Invited)  

NASA Astrophysics Data System (ADS)

Glacier outburst floods discharge large volumes of water from ice-dammed lakes, moraine-dammed lakes, subglacial cavities, or other reservoirs of liquid water. Breaching of moraine- or ice-dammed lakes represent significant hazards for communities adjacent to mountainous regions and a better understanding of the phenomena is warranted. Identifying a unique seismic signature may aid in development of an early warning system and provide the ability to 'remotely' detect when areas are undergoing flooding. We focus efforts on examining seismic data from two distinct regions in Alaska. First, we recorded an outburst flood from a glacier-dammed lake adjacent to Mendenhall Glacier near Juneau, using an array of short- and broadband-period seismometers installed in ice boreholes. We manually pick icequakes and then use the template waveforms in a waveform matching technique that allows us to identify missed events during very active or otherwise noisy time periods. Second, we observe glacier-related seismicity at the Alaska Volcano Observatory network installed on the flanks of Mt Spurr, a relatively active Aleutian arc volcano 130 km west of Anchorage. The activity is plausibly a repeat of a glacier outburst flood that occurred during 1992. During the 1992 flood, an outburst flood exited from beneath a glacier that flows down the southern slope of Mt. Spurr. In both cases, the observed seismicity indicates long, emergent periods (hours to days) of continuous high frequency energy (>10 Hz) at stations closest to the outlet, during vigorous flooding. Secondly, after flooding peaks, distinct short-duration (seconds) icequake events are observed, likely due to collapse of subglacial drainages. No distinct precursors appear in the seismic record, though this may be due to aseismic small-scale failures or ice floatation that lead to the breach.

Walter, J. I.; Amundson, J. M.; Peng, Z.; Prejean, S. G.; Morgan, P.

2013-12-01

277

Mount Cheops Cirque Glacier: Response of a Small Debris Covered Glacier to Climate Change  

E-print Network

Mount Cheops Cirque Glacier: Response of a Small Debris Covered Glacier of a microclimate cirque glacier on Mount Cheops in Glacier National Park of Canada. Rapidly receding glaciers are becoming an important water resource concern

Smith, Dan

278

Quantifying Spatially-Variable Ablation of Bering Glacier Lobes Using Low-Cost Automated Samplers and Remote Sensing Imagery  

NASA Astrophysics Data System (ADS)

The Bering Glacier is the largest and longest glacier in continental North America, with an area of approximately 5,175 km2 and a length of 190 km. It is also the largest surging glacier in America, having surged at least five times during the twentieth century. Bering Glacier alone covers more than 6% of the glacier covered area of Alaska and may contain 15-20% of Alaska's total glacier ice. The entire glacier lies within 100 km of the Gulf of Alaska. The last great surge of the Bering Glacier occurred in 1993-95. An interdisciplinary research team has been actively monitoring the Bering Glacier since 2000, in order to understand the post-surge dynamics in respect to its effect on the Bering Glacier system hydrology. A comprehensive sampling of the lakes, rivers, runoff, and glacier volumetric change is being conducted to understand how changes in the glacier affect the hydrological environment which in turn determines the individual habitat of the flora and fauna that defines the ecology of the region. The monitoring program consists of a combination of highly-detailed local measurements with coarser resolution measurements over large spatial extents. Detailed measurements were collected using an inexpensive, field-deployable data measurement and logging system was designed and fabricated in 2004. The Glacier Ablation Sensor System (GASS) collects environmental information on glacier melting (temperature, barometric pressure, light level, wind speed) and movement (GPS coordinates, depth to glacier surface). The system uses solar cells with a battery to provide the required power, and is capable of storing an entire summer season's worth of hourly data. A set of GASS units (5-8) were deployed during the summers of 2004, 2005, and 2006 on the Bering and Stellar lobes of the Bering Glacier. To complement the local measurements, optical remote sensing imagery has been collected to monitor changes in the glacial terminus and to quantify the spatial variability of albedo. Spatially-variable estimates of ablation were made using an empirical model for the extent of the glacial lobes. The empirical model terms are based on a full energy balance model, and include sensible, latent, and radiative heat fluxes. Point measurements of environmental parameters were spatially distributed based on empirical relationships between parameters and elevation. Temporally- and spatially-variable albedo was estimated based on optical remote sensing data. Discharge to the terminal lakes was estimated based on the modeled ablation, and compared to limited discharge measurements.

Shuchman, R.; Josberger, E.; Erickson, T. A.; Hatt, C.; Liversedge, L.; Roussi, C.; Payne, J. F.

2006-12-01

279

Mapping the Glaciers  

NSDL National Science Digital Library

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.

280

Glossary of Glacier Terminology  

NSDL National Science Digital Library

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.

281

Ablation of Martian glaciers  

NASA Technical Reports Server (NTRS)

Glacier like landforms are observed in the fretted terrain of Mars in the latitude belts near + or - 42 deg. It was suggested that sublimation or accumulation-ablation rates could be estimated for these glaciers if their shapes were known. To this end, photoclinometric profiles were obtained of a number of these landforms. On the basis of analyses of these profiles, it was concluded that ice is chiefly ablating from these landforms that either are inactive rock-glaciers or have materials within them that are moving exceedingly slowly at this time. These conclusions are consistent with other geologic information. The analyses were performed using a two-dimensional model of an isothermal glacier.

Moore, Henry J.; Davis, Philip A.

1987-01-01

282

A strategy for monitoring glaciers  

USGS Publications Warehouse

Glaciers are important features in the hydrologic cycle and affect the volume, variability, and water quality of runoff. Assessing and predicting the effect of glaciers on water resources require a monitoring program to provide basic data for this understanding. The monitoring program of the U.S. Geological Survey employs a nested approach whereby an intensively studied glacier is surrounded by less intensively studied glaciers and those monitored solely by remote sensing. Ideally, each glacierized region of the United States would have such a network of glaciers. The intensively studied glacier provides a detailed understanding of the physical processes and their temporal changes that control the mass exchange of the glaciers in that region. The less intensively studied glaciers are used to assess the variability of such processes within the region.

Fountain, Andrew G.; Krimmel, Robert M.; Trabant, Dennis C.

1997-01-01

283

Geological Field Trips: Glaciers  

NSDL National Science Digital Library

Students will utilize the Internet to take a virtual field trip to visit a glacier and discover what physical effects glaciers have on the land. They will also have the opportunity to virtually visit Vermont and trace the pictorial history of how a whale's fossils were found there. The site also contains a student worksheet for their visual field trip. The site also provides an explanation of the formation of fossils.

Patti Zvanut

2000-03-23

284

Population Trends, Diet, Genetics, and Observations of Steller Sea Lions in Glacier Bay National Park  

E-print Network

Population Trends, Diet, Genetics, and Observations of Steller Sea Lions in Glacier Bay National'Corry-Crowe3 Abstract. We are using demographics, scat analysis, and genetic measurements of Steller sea lions (SSLs)to understand the factors affecting population status throughout Alaska. Steller sea lions

285

Glacier surge mechanism based on linked cavity configuration of the basal water conduit system  

Microsoft Academic Search

Based on observations of the 1982-1983 surge of Variegated Glacier, Alaska, a model of the surge mechanism is developed in terms of a transition from the normal tunnel configuration of the basal water conduit system to a linked cavity configuration that tends to restrict the flow of water, resulting in increased basal water pressures that cause rapid basal sliding. The

Barclay Kamb

1987-01-01

286

Getting the Shot, Grinnell Glacier, Glacier National Park.  

USGS Multimedia Gallery

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....

287

Getting the Shot, Grinnell Glacier, Glacier National Park.  

USGS Multimedia Gallery

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....

288

Mass balance modeling of a large glacier with sparse ground observations, and comparison to three remote sensing techniques  

NASA Astrophysics Data System (ADS)

Like many mountain ranges in Alaska, the Central Alaska Range is a highly glacierized but sparsely monitored region in terms of glacier mass balance and meteorological ground observations. The Kahiltna Glacier, a large (522 km2), remote mountain glacier with a wide range of altitudes and few in-situ measurements, is a challenge for traditional melt models that rely heavily on input of accurate melt gradients, air temperatures and lapse rates, and spatial distribution of snowfall. In order to supplement historical measurements from a single National Park Service mass balance stake, extensive campaigns of field observations were carried out on the glacier in 2010 and 2011, and remaining spatial and temporal gaps have been filled using available climate data products. Here we present a method for modeling twenty years of glacier-wide mass balance evolution for the Kahiltna Glacier, by expanding on sparse ground observations from a single site. We use NCEP-NCAR reanalysis time series' of air temperature and precipitation adjusted to on-glacier conditions, and characterize the spatial distribution of precipitation by sampling a gridded climate product (PRISM) along the glacier centerline. These data serve as input into a fully distributed degree-day melt model. To assess the model results, mass balance estimates obtained from this method are also compared to those derived from several other techniques: DEM differencing, repeat laser altimetry, and regionally downscaled GRACE gravimetry. As well as providing a method for modeling mass balance for a large glacier with a broad elevation range and sparse observational data, this multidisciplinary study will help bridge the gap between modeling and remote sensing techniques for estimating glacier mass balance.

Young, J. C.; Arendt, A. A.; Hock, R. M.; Motyka, R. J.

2012-12-01

289

ALASKA JUSTICE FORUM UNIVERSITY of ALASKA ANCHORAGE  

E-print Network

ALASKA JUSTICE FORUM UNIVERSITY of ALASKA ANCHORAGE A PUBLICATION OF THE JUSTICE CENTER Winter 2007 of the first general study on offender recidivism in Alaska (page 5). A look at incarceration rates in the U.S. as a whole and in Alaska, with a comparison of U.S. rates with rates of other nations (page 7). Total justice

Pantaleone, Jim

290

UNIVERSITY of ALASKA ANCHORAGE ALASKA JUSTICE FORUM  

E-print Network

UNIVERSITY of ALASKA ANCHORAGE ALASKA JUSTICE FORUM A PUBLICATION OF THE JUSTICE CENTER, statewide African-Americans and Alaska Natives could expect to spend 7 days longer in predisposition might have explained some of the disparate outcomes. Preclearance under the Voting Rights Act Alaska

Pantaleone, Jim

291

ALASKA JUSTICE FORUM UNIVERSITY of ALASKA ANCHORAGE  

E-print Network

ALASKA JUSTICE FORUM UNIVERSITY of ALASKA ANCHORAGE A PUBLICATION OF THE JUSTICE CENTER Andr B Justice Center examination ofAlaska State Trooper case files has revealed that the crime of stalking not charged often enough in Alaska. A charge of stalking can be applied in a wide range of situations, and its

Pantaleone, Jim

292

Debris-Free Plateau Glacier  

USGS Multimedia Gallery

Small debris-free plateau glacier with glacier lakes at Gangrinchemzoe Pass at 5,200 m, south of the main Himalayan divide, Bhutan. Image courtesy of Shuji Iwata, Tokyo Metropolitan University, Japan....

293

The GLIMS Glacier Database  

NASA Astrophysics Data System (ADS)

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.

Raup, B. H.; Khalsa, S. S.; Armstrong, R.

2007-12-01

294

Jakobshavn Glacier Retreat (WMS)  

NSDL National Science Digital Library

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 the recession for three years, from 2001 through 2003. The line of recession shows the place where the glacier meets the ocean and where pieces calve off and flow away from land toward open water.

Eric Sokolowsky

2005-03-30

295

Methods used for Undergraduate Education at the University of Alaska Southeast Environmental Sciences Program  

NASA Astrophysics Data System (ADS)

The Environmental Science Program at the University of Alaska Southeast in Juneau, Alaska utilizes our unique outdoor field experience opportunities as part of both the classroom experience and our undergraduate research component. This presentation focuses on our successes in taking advantage of our surrounding environment in the maritime rainforest of the Alaska panhandle to enhance our undergraduate program. We will highlight some of our most successful undergraduate experiences, which include a snow pack monitoring site at our local ski area, glacier mass balance studies on the Mendenhall Glacier, glacial geology studies in Glacier Bay National Park, and the development of wireless networks to monitor bats. We will describe methods we have used to integrate the field opportunities into our program.

Heavner, M. J.; Hood, E. W.; Connor, C. L.

2004-12-01

296

1, 1739, 2007 Glacier balance  

E-print Network

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: 18 June 2007 Correspondence to: M. S. Pelto (mspelto@nichols.edu) 17 #12;TCD 1, 17­39, 2007 Glacier

Paris-Sud XI, Université de

297

Engineering geomorphology of rock glaciers  

NASA Astrophysics Data System (ADS)

A partnership between geomorphology and engineering is facilitating human development in this harsh environment. Rock glaciers provide locations for urban water sources, construction borrow sources, drill sites, shaft and tunnel portals, ski tower supports, and dam abutments. Rock glaciers, as dynamic landforms, necessitate proper identification in the field. Placing structures on, in, or adjacent to rock glaciers requires an appreciation and understanding of their temporal stability. Internal and surface characteristics provide important clues to the development and deformation of rock glaciers. Rock glaciers play a significant role in the alpine debris transport system. Active movement and mass wasting are perhaps the most obvious geologic hazards affecting engineered works. The structure of the rock glacier is conducive to the production of a steady, continuous supply of meltwater during summer months. Thus, rock glaciers serve as alpine aquifers. Consideration of rock glaciers as potential aquifer sources requires caution because of the long-term impact of climate change on the temporal nature of the landform. From the rock glaciers that we have monitored for water quality characteristics, it appears that they provide quality potable water. This paper provides a foundation for appreciation and understanding of rock glaciers from an engineering geomorphologic point of view. The approach taken in this paper provides practical, important information to aid the engineer and engineering geologist in prudent evaluations of rock glaciers as potential sites for human development and uses. The bottom line of our paper is: rock glaciers must be avoided for essentially all structures.

Burger, K. C.; Degenhardt, J. J.; Giardino, J. R.

1999-12-01

298

Denali Fault: Black Rapids Glacier  

USGS Multimedia Gallery

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...

299

Iceland Glacier Recession 1973 to 2000, Glacier Terminus contrast emphasized  

NSDL National Science Digital Library

This animation shows glacier recesion at the Breidamerkurjokull glacier in Iceland. The data from 1973 is taken from Landsat 1 and the 2000 data is from Landsat 7. The Breidamerkurjokull glacier in Iceland has been measured by Landsat to be receding since 1973. The glacierologists in Iceland and here at Nasas Goddard Space Flight Center have measured the recession throughout the entire glacier and found different rates of recession in different areas. In genral, the glacier seems to be receding at about 2% annually. It is extremely controversial whether this recession is caused by global warming.

Lori Perkins

2001-04-09

300

Karakoram glacier surge dynamics  

NASA Astrophysics Data System (ADS)

We examine the surges of five glaciers in the Pakistan Karakoram using satellite remote sensing to investigate the dynamic nature of surges in this region and how they may be affected by climate. Surface velocity maps derived by feature-tracking quantify the surge development spatially in relation to the terminus position, and temporally with reference to seasonal weather. We find that the season of surge initiation varies, that each surge develops gradually over several years, and that maximum velocities are recorded within the lowermost 10 km of the glacier. Measured peak surge velocities are between one and two orders of magnitude greater than during quiescence. We also note that two of the glaciers are of a type not previously reported to surge. The evidence points towards recent Karakoram surges being controlled by thermal rather than hydrological conditions, coinciding with high-altitude warming from long-term precipitation and accumulation patterns.

Quincey, D. J.; Braun, M.; Glasser, N. F.; Bishop, M. P.; Hewitt, K.; Luckman, A.

2011-09-01

301

Climate regime of Asian glaciers revealed by GAMDAM Glacier Inventory  

NASA Astrophysics Data System (ADS)

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 median elevation of glaciers, which is presumed to be at equilibrium-line altitude (ELA) so that mass balance is zero at that elevation, by tuning adjustment parameters of precipitation. We also made comparisons between median elevation of glaciers, including the effect of drifting snow and avalanche, and eliminated those local effects. Then, we could obtain 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 the arid High Mountain Asia have very less precipitation, while much precipitation contribute 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.

Sakai, A.; Nuimura, T.; Fujita, K.; Takenaka, S.; Nagai, H.; Lamsal, D.

2014-07-01

302

Greenland Glacier Albedo Variability  

NASA Technical Reports Server (NTRS)

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.

2004-01-01

303

Northern Illinois University: Glaciers  

NSDL National Science Digital Library

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.

304

Implications for the dynamic health of a glacier from comparison of conventional and reference-surface balances  

USGS Publications Warehouse

Conventional and reference-surface mass-balance data from Gulkana and Wolverine Glaciers, Alaska, USA, are used to address the questions of how rapidly these glaciers are adjusting (or 'responding') to climate, whether their responses are stable, and whether the glaciers are likely to survive in today's climate. Instability means that a glacier will eventually vanish, or at least become greatly reduced in volume, if the climate stabilizes at its present state. A simple non-linear theory of response is presented for the analysis. The response of Gulkana Glacier is characterized by a timescale of several decades, but its stability and therefore its survival in today's climate are uncertain. Wolverine seems to be responding to climate more slowly, on the timescale of one to several centuries. Its stability is also uncertain, but a slower response time would make it more susceptible to climate changes.

Harrison, W.D.; Cox, L.H.; Hock, R.; March, R.S.; Pettit, E.C.

2009-01-01

305

Svalbard surging glacier landsystems  

NASA Astrophysics Data System (ADS)

The percentage of Svalbard glaciers thought to be of surge-type is somewhere between 13-90% according to different sources variously based on statistical analysis and observations of diagnostic glaciological and geomorphological features, e.g. looped moraines. Developing a better understanding of which of these figures, if either, is most realistic is important in the context of glacier dynamics and related contributions of small glaciers and ice caps to sea level change in the immediate future. We present detailed geomorphological assessments of the margins of several known surge-type glaciers in Svalbard in order to update and improve the existing framework by which they are identified, and to provide a foundation for future reassessments of the surge-type glacier population based on distinct landform-sediment assemblages. Three landsystems are proposed: (1) Surges of small valley glaciers produce a prominent ice-cored latero-frontal moraine at their surge maximum and are characterised by an inner zone of ice stagnation terrain (hummocky topography, kettle lakes, debris flows) with no or only very few poorly-defined bedforms (crevasse squeeze ridges, eskers and flutes) and no recessional moraines. Many of these glaciers may have surged in the past but show no signs that they have the capability to do so again in the future. (2) Larger land-terminating glaciers, often with several tributaries, typically produce a push moraine complex which contains evidence for multiple advances, as identified from ridge-meltwater channel relationships. The inner zone often contains a large lagoon, partly dammed by the push moraine complex, and widespread ice stagnation terrain. Crevasse squeeze ridges, eskers and flutes are well-defined but small and limited in number and distribution. (3) Surges of large tidewater glaciers produce distinctive, often multi-generational, landform assemblages both in submarine and lateral terrestrial positions. The well-preserved submarine record is characterised by large cross-fjord push moraines of fjord floor sediments with lobe-shaped debris flows on their distal slope, glacial lineations, dense rhombohedral networks of crevasse squeeze ridges, and eskers. Annual push moraines associated with the quiescent phase are also observed and are unique to the submarine record. The terrestrial record consists of large lateral moraine systems alongside the fjord which contain outer push ridges composed of shallow marine sediments and an inner zone of ice stagnation terrain. Eskers, flutes and large, sharp-crested crevasse fill ridges in dense networks are superimposed on this inner zone; the latter are similar in character to their submarine counterparts but typically higher. We suggest that these three landsystems broadly characterise the geomorphology of the vast majority of known Svalbard surge-type glaciers and may allow previously unknown surge-type glaciers to be identified, both in the field and from aerial photographs and sea floor imagery.

Lovell, Harold; Benn, Douglas; Lukas, Sven; Flink, Anne

2014-05-01

306

Glaciers show direct linkage between erosion rate and chemical weathering fluxes  

NASA Astrophysics Data System (ADS)

Field studies suggest a linkage between high physical erosion rates and rates of chemical denudation. Mechanical erosion by temperate glaciers is commonly an order of magnitude higher than in mountainous fluvial catchments, leading to an expectation that chemical weathering fluxes should also be high from glacierized basins. Yet solute fluxes from glaciers are not found to be higher than non-glacierized catchments. Application of a model of silicate weathering from glaciers based on mineral surface area production and mineralogy shows that solute fluxes are consistent with the low temperatures, dilute water chemistry, and high mineral surface area production in these environments. Low temperatures reduce silicate-weathering rates; this effect explains the difference between silica fluxes from glaciers and from non-glacierized basins. As in laboratory flow-through reactors, glacial solute flux should depend on surface area production and mineral weathering rate constants. The surface area production is significant: a typical glacial erosion rate and grain-size distribution produces on the order of 10 4 km 2 of mineral surface area per square kilometer per year. This new surface area is highly reactive because mineral weathering rates decline with surface age. Application of the "reactor" model yields results largely consistent with measured solute fluxes for the example of Bench Glacier, Alaska. The model underpredicts potassium fluxes, probably due to accelerated initial dissolution of biotite strained by abrasion. The success of the model in predicting other silicate weathering fluxes reflects the far-from-equilibrium conditions in glacial runoff, such that mineral weathering rate constants are not limited by saturation state. In a small data set from glacial catchments, both annual silica fluxes and mean concentrations increase with water discharge. This suggests that mineral surface area increases with water discharge from glaciers, an effect plausibly linked to erosion rates. Those glaciers for which both erosion rate and silica flux data are available support the idea that production of new reactive mineral surface area by glacial erosion drives silicate weathering fluxes.

Anderson, Suzanne Prestrud

2005-04-01

307

A World of Changing Glaciers: Hazards, Opportunities, and Measures of Global Climate Change  

NASA Astrophysics Data System (ADS)

Glaciers around the world are, with rare exceptions, stagnating or in hasty retreat. Whether growing or shrinking, significant changes in the extent of glaciers have major impacts on nature and humanity in their immediate vicinity, because land uses are utterly different depending on whether the land is covered by ice. Upon glacier retreat, new land uses may become possible: (1) Transportation corridors may become feasible where previously there were barriers. (2) Exposure of the lithosphere may yield mineral riches that previously were inaccessible. (3) New wildlife habitat and migration routes may develop, thus promoting genetic diffusion/interbreeding of previously isolated populations. Glacier impacts go well beyond the locality where they occur. Many glaciers regulate water flow, and contribute to annual water availability and hydropower production. In some regions, such in the Hindu Kush-Himlaya (HKH), especially the western provinces of China, the carrying capacity of the land and further economic development and well-being of the populace is partly dependent on melting glaciers. In India, \\8 billion worth of hydroelectric power (at U.S. electric rates) is generated each year; 50% of that is attributable to runoff from Himalayan glaciers and high-altitude snow fields. Nearly \\1 billion worth of hydroelectric power is due to the current negative mass balance of glaciers. In Nepal, glaciogenic hydropower is even more crucial. Although it may be many decades in coming, the ongoing sharp reduction in glacier area in the HKH will eventually be reflected in heightened water shortages in a region where water already is in short supply. Other glaciers store large amounts of meltwater and release it suddenly, causing havoc and taking lives downstream. This is a major problem in the HKH region and is significant locally in other heavily glaciated regions, such as Alaska. Sea level is a global issue impacted significantly by melting glaciers wherever they occur. Receding and wasting glaciers is a chief telltale sign that global climate change is real and accelerating. Although details of glacier responses to climate change are very complex and not always according to inuition, the basic idea that glaciers tend to melt when the climate warms is understood by the public. Thus, public knowledge of glacier change may help prompt millions of individuals to modify their climate-altering behaviors. The net loss or benefit of receding glaciers has not been calculated, but the effect is apt to be sharply negative. Long-term, negative economic impacts related to water resources and sea level are likely to be the largest concerns. However, an objective accounting must consider positives as well. In Alaska alone, an estimated 20,000 square km of "new land" will emerge from beneath ice over the next century. At present rates of generation of goods and services averaged over Alaska's whole area, this land will be worth at least \\$360M per year, plus other noneconomic benefits. For a variety of reasons, its actual value will likely be far greater, thus partly offsetting the considerable disruptive effects of glacier recession.

Kargel, J. S.; Wessels, R.; Kieffer, H. H.

2002-05-01

308

Melting Glaciers Threaten Peru  

NSDL National Science Digital Library

Thousands of people in the Andes mountains of Peru are having their lives affected in both a practical and cultural way by climate change, which is causing the region's glaciers to melt. This document explores the causes of the glacial melt and its impacts on the local cultures.

2003-10-09

309

Taking a Glacier's Pulse  

NSDL National Science Digital Library

This article profiles Dr. Leigh Stearns, a research scientist with the National Science Foundation's Science and Technology Center for Remote Sensing of Ice Sheets (CReSIS) and Assistant Professor in Geology at the University of Kansas who studies glaciers in Greenland.

Carol Landis

310

Glaciers and Glaciation  

NSDL National Science Digital Library

This web page contains 23 multiple-choice practice exam questions on the topic glaciers and glaciation. It is part of the Principles of Earth Science course at the University of South Dakota. Users select an answer, then click to see if it is correct.

Timothy Heaton

311

Gifts of the Glaciers  

NSDL National Science Digital Library

This website highlights the glacial formation of the Great Lakes: - Lake Superior, Lake Huron, Lake Michigan, Lake Erie and Lake Ontario. This site provides photos and descriptions of the lakes and how they formed by the glaciers thousands of years ago.

Stephen Wittman

312

Changing Planet: Melting Glaciers  

NSDL National Science Digital Library

This NBC Learn video features climate scientists doing their research on Mt. Kilimanjaro to study the climate of the past. The scientists put the recently observed changes on the glacier into perspective by comparing past climate fluctuations, stressing that the current observed rate of change is unprecedented.

NBC Learn video - Changing Planet

313

Glaciers and Glaciation  

NSDL National Science Digital Library

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.

Stephen Nelson

314

Gifts of the Glaciers Glacial Landforms  

E-print Network

Gifts of the Glaciers Glacial Landforms Gifts of the Glaciers Moving ice of glacier was responsible. Glaciers perform, in many ways, like an excavator. Although they can push weak material, like gravel, like it in place, like a ripper. And, like a bulldozer, glaciers are poor at eroding rock unless it is already

Cochran-Stafira, D. Liane

315

Glacier Recession Prepared by Joni L. Kincaid  

E-print Network

Glacier Recession Prepared by Joni L. Kincaid for the Advancing Geospatial Skills in Science funded by the National Science Foundation's GK-12 Program. Spring, 2007 #12;Glacier: a large mass of ice Line Glacier How do glaciers form? Glaciers form in locations where the snow does not melt over

316

On the instability of avalanching glaciers  

Microsoft Academic Search

The instability of hanging glaciers and more generally of avalanching glaciers is discussed on the basis of observations performed on several glaciers located in the European Alps. A classification of avalanching glaciers is proposed, which allows a primary appreciation of the danger inherent in these glaciers. On the basis of field observations and results of numerical simulations of crevassing, the

Antoine Pralong; Martin Funk

2006-01-01

317

Annual satellite imaging of the world's glaciers Assessment of glacier extent and change  

E-print Network

GLIMS HIGH ICE Annual satellite imaging of the world's glaciers Assessment of glacier extent and change Development and population of a digital glacier data inventory #12;Glaciers of High Asia: Where was a debris-covered glacier near Mt. Everest J.S. Kargel, April 2001 #12;Gangotri Glacier, India #12;A. Kääb

318

Observed changes in glaciers in China  

NASA Astrophysics Data System (ADS)

Small glaciers are highly sensitive to changes in temperature and precipitation making them important indicators of regional climate change. At present, worldwide evaluation and prediction of glacier change are based on or aided by detailed observations from a small number of glaciers due to the inaccessibility of many glacier areas. Thus, the ground-based detailed glacier monitoring is of strong need and extremely important for glacier variability evaluation in both regional and global scale. China has 46,377 glaciers with a total area of 59,425 km2 and 5600 km3 in volume. Most of the glaciers have experienced rapid and accelerated shrinkage during last few decades. Although some of the glaciers have been investigated or observed through field expeditions and ground-based monitoring, the information of the glacier changes are poorly documented and relatively new to international community. This paper summarizes the observed changes of 9 reference glaciers in China: 1) Urumqi Glacier No. 1, located at the headwaters of Urumqi River in eastern Tianshan which is the best observed glacier in China; 2) Haxilegen Glacier No. 51, at Kuitun River in eastern Tianshan; 3) Qingbingtan Glacier No.72, located at the upper reach of Aksu River in the middle of Tianshan; 4) Miaoergou ice cap, located in the most east part of Tianshan; 5) Laohugou Glacier No. 12, located in Shule River in Qinlian Mountains; 6) Qi Yi glacier (also named as July First Glacier), located in Qinlian Mountains; 7) Dongkemadi Glacier located in Tianggula Mountains in Qinghai-Xizang (Tibetan) Plateau; 8) Rongbu Glacier at the north slop of Mt. Everest in Himalaya Mountains; and 9) Baishui Glacier No. 1, the only temperate glacier in this glacier group, located at Yulong Snow Mountain. Geographically those reference glaciers well represent the glaciers in the major high mountain system in western China. In addition, they have been monitored for 5-53 years and promise the best datasets for glacier changes in their regions.

Li, L.; Li, H.; Wang, F.

2012-04-01

319

Ongoing calving-frontal dynamics of glaciers in the Northern Patagonia Icefield, Chile  

NASA Astrophysics Data System (ADS)

Patagonian glaciers are increasingly contributing to the global-sea level rise due to negative mass balances in recent decades, in spite of moderated temperature and precipitation changes taking place in the region. The Austral Chilean glaciers retreat and thinning are strongly influenced by local topography and frontal characteristics, both playing a key role in disrupting glacier responses. One of the main ice bodies in this region is the Northern Patagonian Icefield ( NPI, 46S/73W, 3953 km2), a plateau from where tens of outlet glaciers have been inventoried. Many of these glaciers are ending at sea or freshwater lakes where they are calving. This calving feature is typically associated to non-climatic fluctuations characterized by abnormally-high and sudden retreat and other exacerbated behaviors such as ice flow acceleration and dynamical thinning. The main aim of this work is the study of recent calving dynamics of three glaciers of the NPI, in order to analyze similarities versus differences associated to their location, topographical constraints and bathymetry, among other features. With this aim, airborne LIDAR and radar surveys, as well as field trips were conducted to the area in year 2012 where several instruments and sensors were installed. The selected study sites were the NPI eastern side freshwater calving glaciers Colonia (47.19S/73.29W) and Nef (47.03S/73.27W), and the NPI western margin tidewater calving San Rafael glacier (46.70S/73.76W). With all the collected data, calving fluxes of 0.03 km3 a-1 and 0.08 km3 a-1 were detected at Glaciares Colonia and Nef respectively. At San Rafael, the calving flux was much higher (0.94 km3 a-1) mainly due to a deeper bathymetry near the glacier front, and very high velocities (10m d-1) compared to the eastern side glaciers. At Glaciar San Rafael the calving flux is very likely modulated by tidal components and local buoyancy conditions, while at the eastern glaciers, calving is a near marginal feature compared with ongoing thinning rates due to higher ablation. In the long term perspective, San Rafael is a good example of the tidewater calving cycle described for several glaciers in Alaska and Patagonia. At the eastern side glaciers, frontal retreats have been bigger than at San Rafael in recent years, but in the long term (since the Little Ice Age), San Rafael experienced a much stronger frontal recession (more than 12 km). This contrasting calving behavior between eastern and western margin glaciers, is only enhancing ice losses differences, but not changing ongoing receding trends.;

Bown, F.; Rivera, A.; Burger, F.; Carrin, D.; Cisternas, S.; Gacita, G.; Pena, M.; Oberreuter, J.; Silva, R.; Uribe, J. A.; Wendt, A.; Zamora, R.

2013-05-01

320

100 Years of Glacier Retreat in Central Asia  

E-print Network

100 Years of Glacier Retreat in Central Asia 100 Years of Glacier Retreat in Central Asia · Jeffrey+GLIMS Glacier databaseMODIS+GLIMS Glacier database #12;Benchmark GlaciersBenchmark Glaciers #12;Everest ASTER Mosaic, 2001Everest ASTER Mosaic, 2001 #12;KhumbuKhumbu Glacier, Nepal, 1958Glacier, Nepal, 1958 #12

321

2011 Updates on the Long-term Glacier Monitoring Program in Denali National Park and Preserve  

NASA Astrophysics Data System (ADS)

The area of Denali National Park and Preserve (DENA) dominated by ice is vast, with glaciers covering 3,780 km^2, approximately one sixth of the park's area. They are integral components of the region's hydrologic, ecologic, and geologic systems - with changes to the glacier systems driving the dependent ecosystems. The National Park Service (NPS) conducts long term monitoring of glaciers in Denali with a variety of methods at a range of spatial and temporal scales. This includes seasonal mass balance and surface movement data collection, annual searches for surging glaciers, and decadal areal extent mapping and volume change estimates of all glaciers in the park. If a glacier surge is detected, the event is documented via photography and surface measurements, when possible. In addition, more intensive ground-based GPS surveys of termini and ice surface elevations are conducted on ten study glaciers every 5-10 years, on a rotating basis. Many of the glaciers are located in designated Wilderness, hence the use of mechanized transport is reduced as much as possible. Monitoring objectives are accomplished by park staff and with cooperative agreements with other agencies and universities. Research to understand the context of the long term data is encouraged and supported as much as possible by the NPS and has recently yielded significant results. The year 2011 marks the 20th anniversary of glacier mass balance monitoring on Kahiltna and Traleika Glaciers, located on the south and north sides of Mt. McKinley respectively. A single "index" site near the ELA of each glacier provides an index of winter, summer, and net balances each year as well as flow velocities and changes in surface elevation. Long-term net balance trends are positive from 1991-2003, and negative since 2003, including the 2009-2010 balance year. The average flow velocity at the Kahiltna index site is 200 +/- 21 m/year with a neutral to slightly negative trend, while on Traleika average velocity is 67 +/- 29 m/year with a positive trend. Monitoring glacier behavior and trends using a variety of techniques provides insight to the complexity of glacier change and increases our ability to distinguish local effects from regional and global trends. Parkwide analysis of glacier extent change since the 1950's shows a consistent trend of retreat, except for glaciers that have surged. Longitudinal surface elevation profiling and comparative photography shows relative stability in larger glaciers, but dramatic long-term mass loss on small, relatively low elevation, valley glaciers characteristic of the eastern portion of DENA. These patterns of ice loss are somewhat unique to the Alaska Range and contrast with big losses of ice mass from large glaciers that border the Gulf of Alaska.

Burrows, R. A.; Adema, G. W.; Herreid, S. J.; Arendt, A. A.; Larsen, C. F.

2011-12-01

322

Life Cycle of a Glacier  

NSDL National Science Digital Library

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.

323

Deep-seated gravitational slope deformations near the Trans-Alaska Pipeline, east-central Alaska Range, Alaska, USA  

NASA Astrophysics Data System (ADS)

Multiple, active, deep-seated gravitational slope deformations (DSGSD) are present near the Trans-Alaska Pipeline and Richardson Highway in the east-central Alaska Range, Alaska, USA. We documented spatial and temporal variations in rates of surface movement of the DSGSDs between 2003 and 2011 using RADARSAT-1 and RADARSAT-2 D-InSAR images. Deformation rates exceed 10 cm/month over very large areas (>1 km2) of many rock slopes. Recent climatic change and strong seismic shaking, especially during the 2002 M 7.9 Denali Fault earthquake, appear to have exacerbated slope deformation. We also mapped DSGSD geological and morphological characteristics using field- and GIS-based methods, and constructed a conceptual 2D distinct-element numerical model of one of the DSGSDs. Preliminary results indicate that large-scale buckling or kink-band slumping may be occurring. The DSGSDs are capable of generating long-runout landslides that might impact the Trans-Alaska Pipeline and Richardson Highway. They could also block tributary valleys, thereby impounding lakes that might drain suddenly. Wrapped 24-day RADARSAT-2 descending spotlight interferogram showing deformation north of Fels Glacier. The interferogram is partially transparent and is overlaid on a 2009 WorldView-1 panchromatic image. Acquisition interval: August 2 - August 26, 2011. UTM Zone 6N.

Newman, S. D.; Clague, J. J.; Rabus, B.; Stead, D.

2013-12-01

324

Glacier National Park  

NSDL National Science Digital Library

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.

325

Postglacial vegetation history of Mitkof Island, Alexander Archipelago, southeastern Alaska  

Microsoft Academic Search

An AMS radiocarbon-dated pollen record from a peat deposit on Mitkof Island, southeastern Alaska provides a vegetation history spanning ?12,900cal yr BP to the present. Late Wisconsin glaciers covered the entire island; deglaciation occurred >15,400cal yr BP. The earliest known vegetation to develop on the island (?12,900cal yr BP) was pine woodland (Pinus contorta) with alder (Alnus), sedges (Cyperaceae) and

Thomas A. Ager; Paul E. Carrara; Jane L. Smith; Victoria Anne; Joni Johnson

2010-01-01

326

A possible Younger Dryas record in southeastern Alaska  

Microsoft Academic Search

A stratigraphic record of climatic cooling equal in timing and severity to the Younger Dryas event of the North Atlantic region has been obtained form lacustrine sediments in the Glacier Bay area of southeastern Alaska. Fossil pollen show that a late Wisconsin pine parkland was replaced about 10,800 years ago by shrub- and herb-dominated tundra, which lasted until about 9,800

D. R. Engstrom; B. C. S. Hansen; H. E. Jr. Wright

1990-01-01

327

Ocean Observing System Demonstrated in Alaska  

NASA Astrophysics Data System (ADS)

To demonstrate the utility of an ocean observing and forecasting system with diverse practical applicationssuch as search and rescue, oil spill response (perhaps relevent to the current Gulf of Mexico oil spill), fisheries, and risk managementa unique field experiment was conducted in Prince William Sound, Alaska, in July and August 2009. The objective was to quantitatively evaluate the performance of numerical models developed for the sound with an array of fixed and mobile observation platforms (Figure 1). Prince William Sound was chosen for the demonstration because of historical efforts to monitor ocean circulation following the 1989 oil spill from the Exxon Valdez tanker. The sound, a highly crenulated embayment of about 10,000 square kilometers at approximately 60N latitude along the northern coast of the Gulf of Alaska, includes about 6900 kilometers of shoreline, numerous islands and fjords, and an extensive system of tidewater glaciers descending from the highest coastal mountain range in North America. Hinchinbrook Entrance and Montague Strait are the two main deep water connections with the Gulf of Alaska. The economic base of communities in the region is almost entirely resource-dependent. For example, Cordova's economy is based on commercial fishing and Valdez's economy is supported primarily by the trans-Alaska oil pipeline terminal.

Schoch, G. Carl; Chao, Yi

2010-05-01

328

Biogeochemistry of glacial runoff along the Gulf of Alaska  

NASA Astrophysics Data System (ADS)

Glaciers and ice sheets represent the second largest reservoir of water in the global hydrologic system and glacier ecosystems cover 10% of the Earth, however the biogeochemistry of glacier discharge has not been well characterized. Preliminary investigations have shown that runoff from glaciers can be an important contributor of dissolved organic carbon (DOC) and macro- and micro- nutrients such as P and Fe to downstream aquatic ecosystems. There is also mounting evidence that glacier ecosystems may be a source of anthropogenically derived constituents such as fossil fuel combustion by-products and persistent organic pollutants that are deposited in precipitation and released in melting glacier ice. As a result, it is critical to develop our understanding of glacial biogeochemistry, particularly in near-shore marine ecosystems along glacially-dominated coastal margins that receive large volumes of glacial runoff. To examine the spatial and temporal variability in the biogeochemical properties of glacial runoff, we sampled snow, ice melt, and glacial runoff at the Mendenhall Glacier near Juneau, Alaska during the summer of 2012. Mendenhall Glacier extends from near-sea level to >1700 m.a.s.l. and encompasses ~120 km2 of the 3900 km2 Juneau Icefield. The main sub-glacial drainage channel was sampled weekly throughout the glacier melt season (May-October) for a suite of physical (temperature, conductivity, suspended sediment) and biogeochemical (C, N, P, Fe and trace metals) parameters. In addition, we did opportunistic sampling of snow in the glacier accumulation zone and supra-glacial meltwater streams on the glacier surface. We also analyzed particulate and dissolved Hg in glacial runoff to quantify the export of Hg to downstream aquatic ecosystems. Preliminary results show that concentrations of dissolved organic carbon in snow, ice melt, and sub-glacial runoff were typically low (<0.5 mg C/L) and not well correlated with discharge. Recent research has shown that glacier-derived DOC represents a quantitatively significant energy subsidy of ancient, yet highly bioavailable carbon to downstream ecosystems. This runs counter to the standard perception of the age-reactivity relationship for DOC, in which the least reactive material withstands degradation the longest and is therefore the oldest. To investigate this phenomenon and determine the origin of glacially-derived DOC, we focused on characterizing the dissolved organic matter being exported from Mendenhall across the melt season. This talk will present results from a variety of organic matter characterization techniques including: carbon isotopes (13C and 14C), fluorescence spectrophotometry, and electrospray ionization coupled to FTICR-MS.

Hood, E.; Scott, D.; Vermilyea, A.; Stubbins, A.; Raymond, P.; Spencer, R.

2012-04-01

329

Muir Glacier in Glacier Bay National Monument 2004  

USGS Multimedia Gallery

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 ...

330

Listening to Glaciers: Passive hydroacoustics near marine-terminating glaciers  

USGS Publications Warehouse

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.

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

2012-01-01

331

Northern Alaska  

NASA Technical Reports Server (NTRS)

Seasonal ice in the Beaufort Sea off Alaska's North Slope has begun its spring retreat. This true color MODIS image from March 18, 2002, shows the pack ice in the Chuckchi Sea (left) and Beaufort Sea (top) backing away from its winter position snug up against Alaska's coasts, beginning its retreat into the Arctic Ocean. While not as pronounced in the Beaufort and Chukchi Seas as other part of the Arctic, scientists studying Arctic sea ice over the course of the century have documented dramatic changes in the extent of Arctic sea ice. It retreats farther in the summer and does not advance as far in the winter than it did a half-century ago. Both global warming and natural variation in regional weather systems have been proposed as causes. Along the coastal plain of the North Slope, gray-brown tracks (see high-resolution image) hint at melting rivers. South of the North Slope, the rugged mountains of the Brooks Range make a coast-to-coast arc across the state. Coming in at the lower right of the image, the Yukon River traces a frozen white path westward across half the image before veering south and out of view. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

2002-01-01

332

University of Alaska Graduate Survey  

E-print Network

University of Alaska Graduate Survey 2012 Prepared for: University of Alaska March 2013 #12;University of Alaska Graduate Survey 2012 Prepared for: University of Alaska Prepared by: Juneau Anchorage ............................................................................................................................... 60 Survey Instrument

Ickert-Bond, Steffi

333

Rapid viscoelastic uplift in southeast Alaska caused by post-Little Ice Age glacial retreat  

Microsoft Academic Search

Our observations show that extreme uplift in southeast Alaska began about 1770 AD, with relative sea level (RSL) change to 5.7 m and current uplift rates to 32 mm\\/yr. This region experienced widespread glacial melting following the Little Ice Age (LIA), with the collapse of the Glacier Bay Icefield alone equivalent to 8 mm of global sea level rise. Geodynamic

Christopher F. Larsen; Roman J. Motyka; Jeffrey T. Freymueller; Keith A. Echelmeyer; Erik R. Ivins

2005-01-01

334

Early and late Holocene glacial fluctuations and tephrostratigraphy, Cabin Lake, Alaska  

E-print Network

Early and late Holocene glacial fluctuations and tephrostratigraphy, Cabin Lake, Alaska PAUL D 1 October 2013 ABSTRACT: Marked changes in sediment types deposited in Cabin Lake, near Cordova in the terminal position of Sheridan Glacier. Cabin Lake is situated to receive meltwater during periods when

Anderson, R. Scott

335

Page 1 Alaska Justice Forum ALASKA JUSTICE FORUM  

E-print Network

Page 1 Alaska Justice Forum ALASKA JUSTICE FORUM Winter 2000 UNIVERSITY OF ALASKA ANCHORAGE Vol. 16, No. 4 A Publication of the Justice Center Alaska Justice Statistical Analysis Unit Please see Alaska Natives, page 4 HIGHLIGHTS INSIDE THIS ISSUE An examination of victimization of Alaska Natives

Pantaleone, Jim

336

Effects of Climate Change- Permafrost and Glaciers - Google Earth Virtual Field Trip Activity  

NSDL National Science Digital Library

In this two-part virtual field trip, students will explore permafrost, the effects that climate change has on current infrastructures built on it and other environmental impacts. The 2008 ATEEC Fellows Institute brought 18 environmental science community college and high school instructors to Alaska. They created virtual field trips using Google Earth. Part two of this activity will take your class to various glaciers in Alaska and around the world. Students will learn about the effects climate change has on these receding glaciers and discover what it means on a broader level. Materials include an excellent teacher's guide to help instructors implement this lesson in their classroom. This resource is free to download. Users must first create a login with ATEEC's website to access the file.

337

Glaciers and the Changing Earth  

NSDL National Science Digital Library

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.

338

Chernobyl fallout on Alpine glaciers  

SciTech Connect

Measurements of the gross beta activity of snow samples from four Alpine glaciers contaminated by radioactive fallout from the Chernobyl nuclear accident and a gamma-spectrum analysis of selected samples are reported. The results are discussed with respect to possible risks to the population from using meltwater from these glaciers as drinking water.

Ambach, W.; Rehwald, W.; Blumthaler, M.; Eisner, H.; Brunner, P.

1989-01-01

339

Life Cycle of a Glacier  

NSDL National Science Digital Library

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.

340

ASTER Image of Gangotri Glacier  

USGS Multimedia Gallery

Sept 9, 2001 ASTER image showing the position of the terminus of Gangotri Glacier, India, between 1780 and 2001. Image from Jesse Allen, NASA's Earth Observatory. Glacier retreat boundaries courtesy of the U.S. Land Processes Distributed Active Archive Center...

341

Status and distribution of the Kittlitz's Murrelet Brachyramphus brevirostris along the Alaska Peninsula and Kodiak and Aleutian Islands, Alaska  

USGS Publications Warehouse

The Kittlitz's Murrelet Brachyramphus brevirostris is adapted for life in glacial-marine ecosystems, being concentrated in the belt of glaciated fjords in the northern Gulf of Alaska from Glacier Bay to Cook Inlet. Most of the remaining birds are scattered along coasts of the Alaska Peninsula and Aleutian Islands, where they reside in protected bays and inlets, often in proximity to remnant glaciers or recently deglaciated landscapes. We summarize existing information on Kittlitz's Murrelet in this mainly unglaciated region, extending from Kodiak Island in the east to the Near Islands in the west. From recent surveys, we estimated that ~2400 Kittlitz's Murrelets were found in several large embayments along the Alaska Peninsula, where adjacent ice fields feed silt-laden water into the bays. On Kodiak Island, where only remnants of ice remain today, observations of Kittlitz's Murrelets at sea were uncommon. The species has been observed historically around the entire Kodiak Archipelago, however, and dozens of nest sites were found in recent years. We found Kittlitz's Murrelets at only a few islands in the Aleutian chain, notably those with long complex shorelines, high mountains and remnant glaciers. The largest population (~1600 birds) of Kittlitz's Murrelet outside the Gulf of Alaska was found at Unalaska Island, which also supports the greatest concentration of glacial ice in the Aleutian Islands. Significant populations were found at Atka (~1100 birds), Attu (~800) and Adak (~200) islands. Smaller numbers have been reported from Unimak, Umnak, Amlia, Kanaga, Tanaga, Kiska islands, and Agattu Island, where dozens of nest sites have been located in recent years. Most of those islands have not been thoroughly surveyed, and significant pockets of Kittlitz's Murrelets may yet be discovered. Our estimate of ~6000 Kittlitz's Murrelets along the Alaska Peninsula and Aleutian Islands is also likely to be conservative because of the survey protocols we employed (i.e. early seasonal timing of surveys, strip transects).

Madison, Erica N.; Piatt, John F.; Arimitsu, Mayumi L.; Romano, Marc D.; van Pelt, Thomas I.; Nelson, S. Kim; Williams, Jeffrey C.; DeGange, Anthony R.

2011-01-01

342

Physical and chemical properties of ice in a main valley glacier and a tributary glacier, Gornergletscher,  

E-print Network

Physical and chemical properties of ice in a main valley glacier and a tributary glacier properties of ice in a main valley glacier and a tributary glacier, Gornergletscher, Canton Valais, Switzerland Annika M. Quick Department of Geological Sciences Master of Science Glacier models often fail

Seamons, Kent E.

343

Digital outlines and topography of the glaciers of the American West  

USGS Publications Warehouse

Alpine glaciers have generally receded during the past century (post-Little Ice Age) because of climate warming (Oerlemans and others, 1998; Mann and others, 1999; Dyurgerov and Meier, 2000; Grove, 2001). This general retreat has accelerated since the mid 1970s, when a shift in atmospheric circulation occurred (McCabe and Fountain, 1995; Dyurgerov and Meier, 2000). The loss in glacier cover has had several profound effects. First, the shrinkage of glaciers results in a net increase in stream flow, typically in late summer when water supplies are at the lowest levels (Fountain and Tangborn, 1985). This additional water is important to ecosystems (Hall and Fagre, 2003) and to human water needs (Tangborn, 1980). However, if shrinkage continues, the net contribution to stream flow will diminish, and the effect upon these benefactors will be adverse. Glacier shrinkage is also a significant factor in current sea level rise (Meier, 1984; Dyurgerov and Meier, 2000). Second, many of the glaciers in the West Coast States are located on stratovolcanoes, and continued recession will leave oversteepened river valleys. These valleys, once buttressed by ice are now subject to failure, creating conditions for lahars (Walder and Driedger, 1994; OConnor and others, 2001). Finally, reduction or loss of glaciers reduce or eliminate glacial activity as an important geomorphic process on landscape evolution and alters erosion rates in high alpine areas (Hallet and others, 1996). Because of the importance of glaciers to studies of climate change, hazards, and landscape modification, glacier inventories have been published for Alaska (Manley, in press), China (http://wdcdgg.westgis.ac.cn/DATABASE/Glacier/Glacier.asp), Nepal (Mool and others, 2001), Switzerland (Paul and others, 2002), and the Tyrolian Alps of Austria (Paul, 2002), among other locales. To provide the necessary data for assessing the magnitude and rate of glacier change in the American West, exclusive of Alaska (fig. 1), we are constructing a geographic information system (GIS) database. The data on glacier location and change will be derived from maps, ground-based photographs, and aerial and satellite images. Our first step, reported here, is the compilation of a glacier inventory of the American West. The inventory is compiled from the 1:100,000 (100K) and 1:24,000 (24K)-scale topographic maps published by the U.S. Geological Survey (USGS) and U.S. Forest Service (USFS). The 24K-scale maps provide the most detailed mapping of perennial snow and ice features. This report informs users of the data about the challenges we faced in compiling the data and discusses its errors and uncertainties. We rely on the expertise of the original cartographers in distinguishing permanent snow and ice from seasonal snow, although we know, through personal experience, of cartographic misjudgments. Whether permanent means indefinite or resident for several years is impossible to determine within the scope of this study. We do not discriminate between glacier, defined as permanent snow or ice that moves (Paterson, 1994), and stagnant snow and ice features. Therefore, we leave to future users the final determination of seasonal versus permanent snow features and the discrimination between true glaciers and stagnant snow and ice bodies. We believe that future studies of more regional focus and knowledge can most accurately refine our initial inventory. For simplicity we refer to all snow and ice bodies in this report as glaciers, although we recognize that most probably do not strictly meet the requirements; many may be snow patches.

Fountain, Andrew G.; Hoffman, Matthew; Jackson, Keith; Basagic, Hassan; Nylen, Thomas; Percy, David

2007-01-01

344

Patagonia Glacier, Chile  

NASA Technical Reports Server (NTRS)

This 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.

2000-01-01

345

Primer on glacier flows Christian Heining  

E-print Network

Primer on glacier flows Christian Heining University of Bayreuth, Germany, Department of Applied Mechanics and Fluid Dynamics 1. Why is it important to understand the physics of glaciers? - Glaciers ocean sediments (ice shelfs in antarctica) o pollen - Glaciers contribute to the raise

Sainudiin, Raazesh

346

Glacier Shrinkage and Effects on Alpine Hydrology  

Microsoft Academic Search

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

H. Basagic; A. G. Fountain; D. H. Clark

2004-01-01

347

Canadian Glacier Hydrology, 2003-2007  

Microsoft Academic Search

Glacier hydrological research in Canada from 2002-2007 continues to advance, driven by new observations of glacier retreat in all regions of the country. New observation networks have been formed to study various aspects of glacier change and linkages with the hydrological system. Small- scale studies of accumulation and melt processes on glacier surfaces continue, and are being used to parameterize

Sarah Boon; Gwenn E. Flowers; D. Scott Munro

2009-01-01

348

Spatial distribution of mercury in southeastern Alaskan streams influenced by glaciers, wetlands, and salmon.  

PubMed

Southeastern Alaska is a remote coastal-maritime ecosystem that is experiencing increased deposition of mercury (Hg) as well as rapid glacier loss. Here we present the results of the first reported survey of total and methyl Hg (MeHg) concentrations in regional streams and biota. Overall, streams draining large wetland areas had higher Hg concentrations in water, mayflies, and juvenile salmon than those from glacially-influenced or recently deglaciated watersheds. Filtered MeHg was positively correlated with wetland abundance. Aqueous Hg occurred predominantly in the particulate fraction of glacier streams but in the filtered fraction of wetland-rich streams. Colonization by anadromous salmon in both glacier and wetland-rich streams may be contributing additional marine-derived Hg. The spatial distribution of Hg in the range of streams presented here shows that watersheds are variably, yet fairly predictably, sensitive to atmospheric and marine inputs of Hg. PMID:24035911

Nagorski, Sonia A; Engstrom, Daniel R; Hudson, John P; Krabbenhoft, David P; Hood, Eran; DeWild, John F; Aiken, George R

2014-01-01

349

A moderate resolution inventory of small glaciers and ice caps surrounding Greenland and the Antarctic peninsula  

NASA Astrophysics Data System (ADS)

Current estimates of global Mountain Glacier and Ice Caps (MG&IC) mass changes are subject to large uncertainties due to incomplete inventories and uncertainties in land surface classification. This presentation features mitigative efforts through the creation of a MODIS dependent land ice classification system and its application for glacier inventory. Estimates of total area of mountain glaciers [IPCC, 2007] and ice caps (including those in Greenland and Antarctica) vary 15%, that is, 680 - 785 10e3 sq. km. To date only an estimated 40% of glaciers (by area) is inventoried in the World Glacier Inventory (WGI) and made available through the World Glacier Monitoring System (WGMS) and the National Snow and Ice Data Center [NSIDC, 1999]. Cogley [2009] recently compiled a more complete version of WGI, called WGI-XF, containing records for just over 131,000 glaciers, covering approximately half of the estimated global MG&IC area. The glaciers isolated from the conterminous Antarctic and Greenland ice sheets remain incompletely inventoried in WGI-XF but have been estimated to contribute 35% to the MG&IC sea-level equivalent during 1961-2004 [Hock et al., 2009]. Together with Arctic Canada and Alaska these regions alone make up almost 90% of the area that is missing in the global WGI-XF inventory. Global mass balance projections tend to exclude ice masses in Greenland and Antarctica due to the paucity of data with respect to basic inventory base data such as area, number of glaciers or size distributions. We address the need for an accurate Greenland and Antarctic peninsula land surface classification with a novel glacier surface classification and inventory based on NASA Moderate Resolution Imaging Spectroradiometer (MODIS) data gridded at 250 m pixel resolution. The presentation includes a sensitivity analysis for surface mass balance as it depends on the land surface classification. Works Cited +Cogley, J. G. (2009), A more complete version of the World Glacier Inventory, Ann. Glaciol. 50(53). +Hock, R., M. de Woul, V. Radi and M. Dyurgerov, 2009. Mountain glaciers and ice caps around Antarctica make a large sea-level rise contribution. Geophys. Res. Lett. 36, L07501, doi:10.1029/2008GL037020. +IPCC, Climate Change 2007 The Physical Science Basis, 2007. Contribution of working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (eds. Solomon, S. et al.) Cambridge University Press, Cambridge, UK.

Chen, C.; Box, J. E.; Hock, R. M.; Cogley, J. G.

2011-12-01

350

Recent behaviour of Slovenian glaciers  

NASA Astrophysics Data System (ADS)

Just two glaciers, below the peaks of Triglav (2864 m) and Skuta (2532 m), are persisting in Slovenian Alps, both on a relatively very low elevation. Their present surfaces do not exceed one hectare, thus we can speak only about two glacierets or very small glaciers. The Anton Melik Geographical Institute of the Scientific Research Centre at the Slovenian Academy of Sciences and Arts has regularly performed measurements since 1946. The size of the Triglav glacier, measured in 1946, was 14.4 hectares, and by the year 2012 the glacier had shrunk to a half of a hectare. The direct vicinity of the meteorological station on Mt. Kredarica makes possible an analysis of the dependency of the glacier's fluctuation on weather changes. Several methods of measuring have been applied. Since 1999 we have regularly performed photogrammetric measurements of the glacier, which render possible exact calculations of changes in the glacier's area and volume by individual years. In addition, we also performed georadar measurements in 2000 and 2013. Besides regular annual measurements performed at the end of melting seasons, the Triglav glacier has also been photographed monthly since 1976, from two fixed positions on Mt. Kredarica. In 2012, we performed aerial laser scanning (LIDAR) of the Triglav glacier. While for the last decade of the 20th century we reported that the Triglav glacier has not only retreated but literally disintegrated, in the first decade of the 21st century we can observe its stagnation. Due to the present concave form of the glacier's surface, snow remains on it late into summer, and since the year 2007, the ice of the lower part of the glacier has not been revealed even at the end of the melting season but has remained covered with the firn and snow of previous winters. Should such weather conditions continue and the amount of winter precipitation further increase, the remainder of the Triglav glacier will, though very small in size, continue to exist for next ten years or even more.

Gabrovec, Matej; Ferk, Mateja; Ortar, Jaka

2014-05-01

351

Termini of calving glaciers as self-organized critical systems  

NASA Astrophysics Data System (ADS)

Over the next century, one of the largest contributions to sea level rise will come from ice sheets and glaciers calving ice into the ocean. Factors controlling the rapid and nonlinear variations in calving fluxes are poorly understood, and therefore difficult to include in prognostic climate-forced land-ice models. Here we analyse globally distributed calving data sets from Svalbard, Alaska (USA), Greenland and Antarctica in combination with simulations from a first-principles, particle-based numerical calving model to investigate the size and inter-event time of calving events. We find that calving events triggered by the brittle fracture of glacier ice are governed by the same power-law distributions as avalanches in the canonical Abelian sandpile model. This similarity suggests that calving termini behave as self-organized critical systems that readily flip between states of sub-critical advance and super-critical retreat in response to changes in climate and geometric conditions. Observations of sudden ice-shelf collapse and tidewater glacier retreat in response to gradual warming of their environment are consistent with a system fluctuating around its critical point in response to changing external forcing. We propose that self-organized criticality provides a yet unexplored framework for investigations into calving and projections of sea level rise.

strm, J. A.; Vallot, D.; Schfer, M.; Welty, E. Z.; O'Neel, S.; Bartholomaus, T. C.; Liu, Yan; Riikil, T. I.; Zwinger, T.; Timonen, J.; Moore, J. C.

2014-12-01

352

Climate variations and changes in mass of three glaciers in western North America  

USGS Publications Warehouse

Time series of net and seasonal mass balances for three glaciers in western North America, one in the Pacific Northwest and two in Alaska, show various relationships to Pacific hemisphere climate indexes. During the winter season the two coastal, maritime-regime glaciers, over 2000 km apart, are affected almost identically, albeit inversely, by atmospheric and oceanic conditions in both the tropical and North Pacific. The two Alaska glaciers, only 350 km apart, have almost no coherence. Lag correlations show that in winter the maritime glaciers are influenced by concurrent conditions in the North Pacific, but by conditions in the tropical Pacific in August-September of the prior northern summer. The winter balance variations contain interannual El Nino-Southern Oscillation variability superimposed on North Pacific interdecadal variability; the interdecadal 1976-77 climate regime shift is clearly evident. The summer balances and the continental-regime glacier have a general lack of correlations, with no clear, strong, consistent patterns, probably a result of being influenced more by local processes or by circulation patterns outside the Pacific Ocean basin. The results show the Pacific Northwest is strongly influenced by conditions in the tropical Pacific, but that this teleconnection has broken down in recent years, starting in 1989. During the seven years since then (1989-95), all three glaciers have shown, for the first time, coherent signals, which were net mass loss at the highest rate in the entire record. The authors' results agree with those of other recent studies that suggest these recent years are unusual and may be a signature of climate warming.

Hodge, S.M.; Trabant, D.C.; Krimmel, R.M.; Heinrichs, T.A.; March, R.S.; Josberger, E.G.

1998-01-01

353

Teleconnections between Andean and New Zealand glaciers  

Microsoft Academic Search

Retreat and advance of glaciers in the Southern Alps of New Zealand have occurred over two distinct 20-yr climate periods (19541974) and (19741994). Changes in tropical and southern Andean glaciers are compared over these same periods. Behaviour of glaciers in the tropical Andes are out of phase with the Southern Alps glaciers, but some glaciers in Patagonia appear to be

B. Blair Fitzharris; Gareth R. Clare; Jim Renwick

2007-01-01

354

Indicators of recent environmental change in Alaska  

SciTech Connect

Climate models predict that global warming due to the effects of increasing trace gases will be amplified in northern high latitude regions, including Alaska. Several environmental indicators, including tree-ring based temperature reconstructions, borcal forest growth measurements and observations of glacial retreat all indicate that the general warming of the past century has been significant relative to prior centuries to millenia. The tree-ring records for central and northern Alaska indicate that annual temperature increased over the past century, peaked in the 1940s, and are still near the highest level for the past three centuries (Jacoby and D`Arrigo 1995). The tree-ring analyses also suggest that drought stress may now be a factor limiting growth at many northern sites. The recent warming combined with drier years may be altering the response of tree growth to climate and raising the likelihood of forest changes in Alaska and other boreal forests. Other tree-ring and forest data from southern and interior Alaska provide indices of the response of vegetation to extreme events (e.g., insect outbreaks, snow events) in Alaska (Juday and marler 1996). Historical maps, field measurements and satellite imagery indicate that Alaskan glaciers have receded over the past century (e.g., Hall and Benson 1996). Severe outbreaks of bark beetles may be on the increase due to warming, which can shorten their reproductive cycle. Such data and understanding of causes are useful for policy makers and others interested in evaluation of possible impacts of trace-gas induced warming and environmental change in the United States.

Jacoby, G.C.; D`Arrigo, R.D.; Juday, G.

1997-12-31

355

Alaska's Economy: What's Ahead?  

ERIC Educational Resources Information Center

This review describes Alaska's economic boom of the early 1980s, the current recession, and economic projections for the 1990s. Alaska's economy is largely influenced by oil prices, since petroleum revenues make up 80% of the state government's unrestricted general fund revenues. Expansive state spending was responsible for most of Alaska's

Alaska Review of Social and Economic Conditions, 1987

1987-01-01

356

Alaska Natives & the Land.  

ERIC Educational Resources Information Center

Pursuant to the Native land claims within Alaska, this compilation of background data and interpretive materials relevant to a fair resolution of the Alaska Native problem seeks to record data and information on the Native peoples; the land and resources of Alaska and their uses by the people in the past and present; land ownership; and future

Arnold, Robert D.; And Others

357

Alaska Native Hispanic or  

E-print Network

fCOLLEGEo CHARLESTON American Indian or Alaska Native Asian Black or African American Hispanic Indian or Alaska Native Asian Black or African American Hispanic or Latino Native Hawaiian or Other Enrolled American Indian or Alaska Native Asian Black or African American Hispanic or Latino Native

Kunkle, Tom

358

Alaska Women: A Databook.  

ERIC Educational Resources Information Center

This data book uses survey and census information to record social and economic changes of the past three decades and their effects upon the role of Alaska women in society. Results show Alaska women comprise 47% of the state population, an increase of 9% since 1950. Marriage continues as the predominant living arrangement for Alaska women,

White, Karen; Baker, Barbara

359

Methods of Measuring Glacier Change  

NASA Astrophysics Data System (ADS)

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.

Fountain, A. G.

2001-12-01

360

Co-occurrence of Pacific sleeper sharks Somniosus pacificus and harbor seals Phoca vitulina in Glacier Bay  

USGS Publications Warehouse

We present evidence that Pacific sleeper sharks Somniosus pacificus co-occur with harbor seals Phoca vitulina in Glacier Bay, Alaska, and that these sharks scavenge or prey on marine mammals. In 2002, 415 stations were fished throughout Glacier Bay on a systematic sampling grid. Pacific sleeper sharks were caught at 3 of the 415 stations, and at one station a Pacific halibut Hippoglossus stenolepis was caught with a fresh bite, identified as the bite of a sleeper shark. All 3 sharks and the shark-bitten halibut were caught at stations near the mouth of Johns Hopkins Inlet, a glacial fjord with the highest concentration of seals in Glacier Bay. Using a bootstrap technique, we estimated the probability of sampling the sharks (and the shark-bitten halibut) in the vicinity of Johns Hopkins Inlet. If sharks were randomly distributed in Glacier Bay, the probability of sampling all 4 pots at the mouth of Johns Hopkins Inlet was very low (P = 0.00002). The highly non-random distribution of the sleeper sharks located near the largest harbor seal pupping and breeding colony in Glacier Bay suggests that these 2 species co-occur and may interact ecologically in or near Johns Hopkins Inlet. Copyright ?? 2005 by the Alaska Department of Fish and Game.

Taggart, S.J.; Andrews, A.G.; Mondragon, J.; Mathews, E.A.

2005-01-01

361

Triggering of glacier seismicity (icequakes) by distant earthquakes  

NASA Astrophysics Data System (ADS)

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.

Walter, J. I.; Peng, Z.; Tulaczyk, S. M.; Oneel, S.

2013-05-01

362

Pine Island Glacier, Antarctica  

NASA Technical Reports Server (NTRS)

This ASTER image was acquired on December 12, 2000, and covers an area of 38 x 48 km. Pine Island Glacier has undergone a steady loss of elevation with retreat of the grounding line in recent decades. Now, space imagery has revealed a wide new crack that some scientists think will soon result in a calving event. Glaciologist Robert Bindschadler of NASA's Goddard Space Flight Center predicts this crack will result in the calving of a major iceberg, probably in less than 18 months. Discovery of the crack was possible due to multi-year image archives and high resolution imagery. This image is located at 74.1 degrees south latitude and 105.1 degrees west longitude.

The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

2001-01-01

363

Gallery Walk Questions about Glaciers  

NSDL National Science Digital Library

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 ...

364

UNIVERSITY OF ALASKA ANCHORAGE UNIVERSITY OF ALASKA ANCHORAGE  

E-print Network

UNIVERSITY OF ALASKA ANCHORAGE #12;UNIVERSITY OF ALASKA ANCHORAGE Dear Student, Congratulations on taking the first step toward becoming a college student. At the University of Alaska Anchorage, you Director of Admissions University of Alaska Anchorage Welcome to the UNIVERSITY OF ALASKA Anchorage! #12

Duddleston, Khrys

365

Instructions for Glacier Recession Lesson Objective: Students will learn  

E-print Network

Instructions for Glacier Recession Lesson Objective: Students will learn: - about the connection between glaciers and climate, - why glacial studies are important, - how glacier recession affects humanity, and - how humans are affecting glaciers. Materials: Movie ­ Inconvenient Truth For Exercise

366

Kwday Dn Ts'nch, the first ancient body of a man from a North American glacier: reconstructing his last days by intestinal and biomolecular analyses  

Microsoft Academic Search

We report on scientific analyses of the only well-preserved ancient human body ever recovered from a North American glacier. The body was found high in the mountains of northwest British Columbia at about 80 km from the nearest point of the strongly indented coast of southern Alaska. The geographical location suggests that the young man, aged about 20 years, could

James H. Dickson; Michael P. Richards; Richard J. Hebda; Petra J. Mudie; Owen Beattie; Susan Ramsay; Nancy J. Turner; Bruce J. Leighton; John M. Webster; Niki R. Hobischak; Gail S. Anderson; Peter M. Troffe; Rebecca J. Wigen

2004-01-01

367

The Outlier State: Alaskas FY 2012 Budget  

E-print Network

Although prices for Alaska North Slope (ANS) crude stayed inexplore for oil on the Alaska North Slope. It promised a Alaska has a clearly identified 35 billion cubic meters of natural gas on the North Slope,

McBeath, Jerry; Corbin, Tanya Buhler

2012-01-01

368

FIRE_CI1_SRB_ALASKA  

Atmospheric Science Data Center

FIRE_CI1_SRB_ALASKA Project Title: FIRE I CIRRUS Discipline: ... Guide Documents: SRB Data Set Guide - Alaska, Canada, So Pole, Switz Readme Files: Readme SRB Alaska Header SRB Alaska Table of Contents SRB Alaska ...

2014-05-06

369

Modelling Greenland Outlet Glaciers  

NASA Technical Reports Server (NTRS)

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.

vanderVeen, Cornelis; Abdalati, Waleed (Technical Monitor)

2001-01-01

370

Aletsch Glacier, Switzerland  

NASA Technical Reports Server (NTRS)

Aletsch Glacier, the largest glacier of Europe, covers more than 120 square kilometers (more than 45 square miles)in southern Switzerland. At its eastern extremity lies a glacierlake, Mdrjelensee (2,350 meters/7,711 feet above sea level). To the west rises Aletschhorn (4,195 meters/13,763 feet), which was first climbed in 1859. The Rhone River flows along the southern flank of the mountains.

This image was acquired on July 23, 2001 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet. 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 Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

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.

Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. The Terra mission is part of NASA's Earth Science Enterprise, a long-term research and technology program designed to examine Earth's land, oceans, atmosphere, ice and life as a total integrated system.

Size: 60 x 56 km (37.2 x 34.7 miles) Location: 46.5 deg. North lat., 8.0 deg. East long. Orientation: North at top Image Data: ASTER bands 1,2, and 3. Original Data Resolution: 15 m Date Acquired: July 23, 2001

2002-01-01

371

Annual satellite imaging of the world's glaciers Assessment of glacier extent and change  

E-print Network

GLIMS HIGH ICE Annual satellite imaging of the world's glaciers Assessment of glacier extent and change Development and population of a digital glacier data inventory #12;Skeletal remains of what was a debris-covered glacier near Mt. Everest J.S. Kargel, April 2001 #12;#12;#12;Global Land Ice Measurements

372

The GLIMS geospatial glacier database: A new tool for studying glacier change  

E-print Network

The GLIMS geospatial glacier database: A new tool for studying glacier change Bruce Raup a,, Adina'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

373

Dating of Little Ice Age glacier fluctuations in the tropical Andes: Charquini glaciers, Bolivia, 16S  

Microsoft Academic Search

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

Antoine Rabatel; Vincent Jomelli; Philippe Naveau; Bernard Francou; Delphine Grancher

2005-01-01

374

The triggering of subglacial lake drainage during rapid glacier drawdown: Crane Glacier, Antarctic Peninsula  

E-print Network

The triggering of subglacial lake drainage during rapid glacier drawdown: Crane Glacier, Antarctic Glacier, Antarctic Peninsula, shows an unusual temporal pattern of elevation loss: a period of very rapid is not seen. Bathymetry in Crane Glacier fjord reveals a series of flat-lying, formerly subglacial deeps

Paris-Sud XI, Université de

375

Assessment of multispectral glacier mapping methods and derivation of glacier area changes, 19782002, in the central  

E-print Network

Assessment of multispectral glacier mapping methods and derivation of glacier area changes, 1978 56, Dunedin 9054, New Zealand ABSTRACT. We have measured the glacier area changes in the central Southern Alps, New Zealand, between 1978 and 2002 and have compiled the 2002 glacier outlines using

Kääb, Andreas

376

Water Flow through Widespread and Interconnected Void Spaces at Depth in a Temperate Glacier  

NASA Astrophysics Data System (ADS)

We present a suite of observations that suggest void spaces within the ice mass of Bench Glacier, Alaska are abundant, interconnected, and may offer an important means for englacial water storage and routing. During Spring of 2003, a grid of boreholes spaced 20 x 20 m were drilled to the bed of Bench Glacier, Chugach Mountains, Alaska. The boreholes extended 180 m to the bed of the glacier and totaled more than 3600 m within the 106 m3 block of temperate ice. Each borehole was inspected by video camera multiple times during a four-week period. These video observations show that open, crevasse-shaped void spaces are common in the lower two thirds of the ice depth. Upward water flow with active refreezing was observed in association with the voids. Eventual upwelling of turbid water demonstrated a connection between the voids and the bed. Slug tests and monitored drilling experiments (presented in detail elsewhere) revealed numerous englacial connections between different boreholes of the grid. For example, during the drilling process changes in water level were observed in the partially-drilled borehole that were coincident with changes in extant boreholes. Together, these observations imply that void spaces in the glacier are widespread and interconnected over many 10s of meters. They do not appear to form an aborescent network of channels. Since the voids are apparently well connected to the bed, they provide an additional dimension to the subglacial hydrological system - a place to store and route water. Hence, englacial voids may be an important component of the glacier drainage system and the linkage between hydrology and sliding dynamics.

McGee, B. W.; Harper, J. T.; Humphrey, N. F.; Pfeffer, T. W.

2003-12-01

377

High Altitude Glaciers in the Tropics  

NSDL National Science Digital Library

While it may seem like a contradiction, glaciers do exist in the tropical latitudes. In this video produced by ThinkTV, learn about tropical glaciers and why scientists are studying them to better understand global climate change.

ThinkTV

2010-11-30

378

Hydrology and Flood Profiles of Duck Creek and Jordan Creek Downstream from Egan Drive, Juneau, Alaska  

USGS Publications Warehouse

Hydrologic and hydraulic updates for Duck Creek and the lower part of Jordan Creek in Juneau, Alaska, included computation of new estimates of peak streamflow magnitudes and new water-surface profiles for the 10-, 50-, 100-, and 500-year floods. Computations for the 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year recurrence interval flood magnitudes for both streams used data from U.S. Geological Survey stream-gaging stations weighted with regional regression equations for southeast Alaska. The study area for the hydraulic model consisted of three channels: Duck Creek from Taku Boulevard near the stream's headwaters to Radcliffe Road near the end of the Juneau International Airport runway, an unnamed tributary to Duck Creek from Valley Boulevard to its confluence with Duck Creek, and Jordan Creek from a pedestrian bridge upstream from Egan Drive to Crest Street at Juneau International Airport. Field surveys throughout the study area provided channel geometry for 206 cross sections, and geometric and hydraulic characteristics for 29 culverts and 15 roadway, driveway, or pedestrian bridges. Hydraulic modeling consisted of application of the U.S. Army Corps of Engineers' Hydrologic Engineering Center River Analysis System (HEC-RAS) for steady-state flow at the selected recurrence intervals using an assumed high tide of 20 feet and roughness coefficients refined by calibration to measured water-surface elevations from a 2- to 5-year flood that occurred on November 21, 2005. Model simulation results identify inter-basin flow from Jordan Creek to the southeast at Egan Drive and from Duck Creek to Jordan Creek downstream from Egan Drive at selected recurrence intervals.

Curran, Janet H.

2007-01-01

379

The Alaska Climate Research Center  

NSDL National Science Digital Library

The University of Fairbanks's Alaska Climate Research Center offers a host of materials about its climate research and about Alaska's climate in general. The website supplies abstracts of the Center's research projects such as _The Urban Heat Island Effect at Fairbanks, Alaska_ and _Radiation Climatology of Alaska_. Researchers can find data and statistics on Alaska's temperature, humidity, precipitation, cloudiness, pressure, and wind. The website provides Climographs for various areas throughout the state. Students can discover how latitude, continentiality, and elevation affect Alaska's climate.

380

Glacier Mass Balance measurements in Bhutan  

NASA Astrophysics Data System (ADS)

Long-term glacier measurements are scarce in the Himalayas, partly due to lack of resources as well as inaccessibility of most of the glaciers. There are over 600 glaciers in Bhutan in the Eastern Himalayas, but no long-term measurements. However, such studies are an important component of hydrological modelling, and especially relevant to the proposed expansion of hydropower resources in this area. Glaciological studies are also critical to understanding the risk of jkulhlaups or GLOFS (glacier lake outburst floods) from glaciers in this region. Glacier mass balance measurements have been initiated on a glacier in the Chamkhar Chu region in central Bhutan by the Department of Hydro-Met Services in co-operation with the Norwegian Water Resources and Energy Directorate. Chamkhar Chu is the site of two proposed hydropower plants that will each generate over 700 MW, although the present and future hydrological regimes in this basin, and especially the contribution from glaciers, are not well-understood at present. There are about 94 glaciers in the Chamkhar Chhu basin and total glacier area is about 75 sq. km. The glaciers are relatively accessible for the Himalayas, most of them can be reached after only 4-5 days walk from the nearest road. One of the largest, Thana glacier, has been chosen as a mass balance glacier and measurements were initiated in 2013. The glacier area is almost 5 sq. km. and the elevation range is 500 m (5071 m a.s.l. to 5725 m a.s.l.) making it suitable as a benchmark glacier. Preliminary measurements on a smaller, nearby glacier that was visited in 2012 and 2013 showed 1 m of firn loss (about 0.6 m w.eq.) over 12 months.

Jackson, Miriam; Tenzin, Sangay; Tashi, Tshering

2014-05-01

381

Where Have All the Glaciers Gone?  

NSDL National Science Digital Library

In this activity, students examine images of alpine glaciers to develop an understanding of how glaciers respond to climate change. They record, discuss, and interpret their observations. They consider explanations for changes in the size and position of glaciers from around the world. They develop an understanding that the melting (retreat) of glaciers is occurring simultaneously on different continents around the world, and, thus, they represent evidence of global climate change.

National Center For Atmospheric Research

382

Alaska Volcano Observatory  

USGS Publications Warehouse

Steam plume from the 2006 eruption of Augustine volcano in Cook Inlet, Alaska. Explosive ash-producing eruptions from Alaska's 40+ historically active volcanoes pose hazards to aviation, including commercial aircraft flying the busy North Pacific routes between North America and Asia. The Alaska Volcano Observatory (AVO) monitors these volcanoes to provide forecasts of eruptive activity. AVO is a joint program of the U.S. Geological Survey (USGS), the Geophysical Institute of the University of Alaska Fairbanks (UAFGI), and the State of Alaska Division of Geological and Geophysical Surveys (ADGGS). AVO is one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety. Learn more about Augustine volcano and AVO at http://www.avo.alaska.edu.

Venezky, Dina Y.; Murray, Tom; Read, Cyrus

2008-01-01

383

Longitudinal surface structures (flowstripes) on Antarctic glaciers  

NASA Astrophysics Data System (ADS)

Longitudinal surface structures ("flowstripes") are common on many glaciers but their origin and significance are poorly understood. In this paper we present observations of the development of these longitudinal structures from four different Antarctic glacier systems; the Lambert Glacier/Amery Ice Shelf area, the Taylor and Ferrar Glaciers in the Ross Sea sector, Crane and Jorum Glaciers (ice-shelf tributary glaciers) on the Antarctic Peninsula, and the onset zone of a tributary to the Recovery Glacier Ice Stream in the Filchner Ice Shelf area. Mapping from optical satellite images demonstrates that longitudinal surface structures develop in two main situations: (1) as relatively wide flow stripes within glacier flow units and (2) as relatively narrow flow stripes where there is convergent flow around nunataks or at glacier confluence zones. Our observations indicate that the confluence features are narrower, sharper, and more clearly defined features. They are characterised by linear troughs or depressions on the ice surface and are much more common than the former type. Longitudinal surface structures within glacier flow units have previously been explained as the surface expression of localised bed perturbations but a universal explanation for those forming at glacier confluences is lacking. Here we propose that these features are formed at zones of ice acceleration and extensional flow at glacier confluences. We provide a schematic model for the development of longitudinal surface structures based on extensional flow that can explain their ridge and trough morphology as well as their down-ice persistence.

Glasser, N. F.; Gudmundsson, G. H.

2012-03-01

384

Get Close to Glaciers with Satellite Imagery.  

ERIC Educational Resources Information Center

Discusses the use of remote sensing from satellites to monitor glaciers. Discusses efforts to use remote sensing satellites of the Landsat series for examining the global distribution, mass, balance, movements, and dynamics of the world's glaciers. Includes several Landsat images of various glaciers. (TW)

Hall, Dorothy K.

1986-01-01

385

Fate of Mountain Glaciers in the Anthropocene  

E-print Network

Fate of Mountain Glaciers in the Anthropocene A Report by the Working Group Commissioned of Sciences at the Vatican, to contemplate the observed retreat of the mountain glaciers, its causes and consequences. This report resulted from a workshop in April 2011 at the Vatican. 2007 Courtesy of Glacier

Stocker, Thomas

386

Glaciers and icecaps: Storehouses of freshwater  

NSDL National Science Digital Library

Glacier: Complete description of what glaciers and icecaps are and why they are important to us. Maps show the location of glaciers and icecaps. This resource is part of the "Water Science for Schools" collection at the United States Geological Survey.

387

BIODIVERSITY Accounting for tree line shift, glacier  

E-print Network

BIODIVERSITY RESEARCH Accounting for tree line shift, glacier retreat and primary succession land cover (tree line shift, glacier retreat and primary succession) into species distribution model. Methods We fit linear mixed effects (LME) models to historical changes in forest and glacier cover

Zimmermann, Niklaus E.

388

4, 173211, 2008 Climate and glacier  

E-print Network

CPD 4, 173­211, 2008 Climate and glacier response to ENSO in subtropical Andes E. Dietze et al forum of Climate of the Past Response of regional climate and glacier ice proxies to El Ni of the European Geosciences Union. 173 #12;CPD 4, 173­211, 2008 Climate and glacier response to ENSO

Boyer, Edmond

389

2, 121, 2008 Mountain glaciers of  

E-print Network

TCD 2, 1­21, 2008 Mountain glaciers of NE Asia M. D. Ananicheva et al. Title Page Abstract The Cryosphere Discussions is the access reviewed discussion forum of The Cryosphere Mountain glaciers of NE Asia in the near future: a projection based on climate-glacier systems' interaction M. D. Ananicheva1 , A. N

Boyer, Edmond

390

Glacier variations in the Bernese Alps (Switzerland)  

E-print Network

Glacier variations in the Bernese Alps (Switzerland) ­ Reconstructions and simulations #12;#12;Glacier variations in the Bernese Alps (Switzerland) ­ Reconstructions and simulations Two Alpine glaciers over the last two centuries: a scientific view based on pictorial sources Starting

Steiner, Daniel

391

NASA's DESDynI in Alaska  

NASA Astrophysics Data System (ADS)

In 2007 the National Research Council Earth Science Decadal Survey, Earth Science Applications from Space, recommended an integrated L-band InSAR and multibeam Lidar mission called DESDynI (Deformation, Ecosystem Structure, and Dynamics of Ice) and it is scheduled for launch in 2017. The NASA InSAR and Lidar mission is optimized for studying geohazards and global environmental change. The complex plate boundary in southern coastal Alaska provides an excellent setting for testing DESDynI capabilities to recover fundamental parameters of glacio-seismotectonic processes. Also, aircraft and satellites acquisitions of Lidar and L-band SAR have been made in this region in the last decade that can be used for DESDynI performance simulations. Since the Lidar observations would penetrate most vegetation, the accurate bald Earth elevation profiles will give new elevation information beyond the standard 30-m digital elevation models (DEM) and the Lidar-derived elevations will provide an accurate georeferenced surface for local and regional scale studies. In an earlier study we demonstrated how the Lidar observations could be used in combination with SAR to generate an improved InSAR derived DEM in the Barrow, Alaska region [Atwood et al., 2007]; here we discuss how Lidar could be fused with L-band SAR in more rugged, vegetated terrane. Based on simulations of multi-beam Lidar instrument performance over uplifted marine terraces, active faults and folds, uplift associated with the 1899 Yakataga seismic event (M=8), and elevation change on the glaciers in southern, coastal Alaska, we report on the significance of the DESDynI Lidar contiguous 25 m footprint elevation profiles for EarthScope related studies in Alaska. We are using the morphology and dynamics of glaciers derived from L-band SAR ice velocities to infer the large scale sub-ice structures that form the structural framework of the Seward-Bagley Basins. Using primarily winter acquisitions of L-band SAR data from ALOS/PALSAR (Mode: Fine beam, HH) we have been able to estimate ice velocities from offset-tracking in the Upper and Lower Seward Basin even though the acquisitions are 46 days apart. We anticipate with the shorter repeat time for DESDynI-SAR acquisitions that we will be able to estimate seasonal ice velocities over a larger range of regions within both the ablation and accumulation zones.

Sauber, J. M.; Hofton, M. A.; Bruhn, R. L.; Forster, R. R.; Burgess, E. W.; Cotton, M. M.

2010-12-01

392

Dissolved organic matter export in glacial and non-glacial streams along the Gulf of Alaska  

NASA Astrophysics Data System (ADS)

The Gulf of Alaska drainage basin contains more than 75,000 km2 of glaciers, many of which are rapidly thinning and receding. We are using a paired watershed approach to evaluate how changes in glacier ecosystems will impact the export dissolved organic matter (DOM) into the Gulf of Alaska. Our primary study watersheds, Lemon Creek and Montana Creek, are similar in size, bedrock lithology and elevation range and extend from near sea level to the margin or interior of the Juneau Icefield. Lemon Creek has a glacial coverage of ~60%, while Montana Creek is free of glacier ice. Our goal is to evaluate seasonal differences in the quantity, chemical character and reactivity of DOM being exported from these watersheds to downstream near-shore marine ecosystems. In addition, we are monitoring a variety of physical parameters that influence instream DOM metabolism in both watersheds. Our initial results from the 2009 runoff season indicate that concentrations of dissolved organic carbon (DOC) are substantially higher in the non-glacial watershed. However, fluorescence analyses indicate that DOM from the glacier watershed has a higher protein and lower humic material content compared to DOM from the non-glacial watershed. After the spring snowmelt season, physical parameters between the two watersheds diverged, with higher streamflow and turbidity as well as colder water temperatures in the glacial watershed. Although our previous yield calculations show significantly higher DOC fluxes from the forested watershed, our results here suggest that glacier watersheds may be an important source of labile carbon to the near shore marine ecosystem. The contrast in the physical habitat between the two rivers (e.g glacier stream = cold, low light penetration, unstable substrate) supports the hypothesis that that in-stream DOM processing is limited within glacier dominated rivers, therefore delivering a higher percentage of labile DOM downstream.

Hood, E. W.; Scott, D.; Jeffery, A.; Schreiber, S.; Heavner, M.; Edwards, R.; D'Amore, D. V.; Fellman, J.

2009-12-01

393

Temperature index modeling of the Kahiltna Glacier: Comparison to multiple field and geodetic mass balance datasets  

NASA Astrophysics Data System (ADS)

Glaciers of Alaska, USA, and Northwestern Canada are shedding mass at one of the highest rates of any mountain glacier system, with significant impact at the global and local scales. Despite advances in satellite and airborne technologies, fully characterizing the temporal evolution of glacier mass change in individual watersheds remains a challenge. Temperature index modeling is an approach that can be used to expand on sparse ground observations, and that can help bridge the gap between regional and individual watershed estimates of the time series of glacier mass change. Here we present a study on temperature index modeling of glacier-wide mass balance for the large Kahiltna Glacier (502 km2, 270 to 6100 m in elevation) in the Central Alaska Range, using a combination of ground observations and past climate data products. We reproduce mass changes from 1991 to 2011, and assess model performance by comparing our results to several field and remote sensing datasets. First, we compare our results to a 20-year record of mass balance measurements at a National Park Service index site at the glacier's equilibrium line altitude. We find low correlation between index site measurements and modeled glacier-wide balances (R2 = 0.24), indicating that the index site may not be representative of the glacier-wide mass balance regime. We compare next to glacier-wide mass balances derived from airborne laser altimetry, to assess the model's long-term mass change estimates. We find disagreement between the mean annual balances for 1995 to 2010 (-0.95 +/-0.49 m w.e. yr --1 from the model versus -0.69 +0.07/-0.08 m w.e. yr --1 from laser altimetry). To validate the laser altimetry methods, we then compare estimates from 1951 to 2011 from laser altimetry and digital elevation model differencing, finding close agreement (-0.48 +0.08/-0.09 m w.e. yr--1 and -0.41 +/-0.26 m w.e. yr--1 , respectively), and lending strength to the laser altimetry centerline extrapolation techniques. We also examine estimates derived from regionally-downscaled satellite gravimetry. While gravimetry likely underestimates long-term mass loss for this glacier (-0.36 +/-0.13 m w.e. yr--1 for 2003 to 2010), it correlates well to individual modeled annual balances (R2 = 0.72) and to the time series of mass balance at an ablation stake location (R2 = 0.81). Given ongoing refinements to gravimetry downscaling and geodetic techniques, our results point to the potential for integrating multiple methods to obtain the most information on subannual and long-term mass changes at the basin scale for remote sites such as the Kahiltna Glacier.

Young, Joanna C.

394

Glacier recession in Iceland and Austria  

SciTech Connect

It has been possible to measure glacier recession on the basis of Landsat data, in conjunction with comparisons of the magnitude of recession of a glacier margin with in situ measurements at fixed points along the same margin. Attention is presently given to the cases of Vatnajokull ice cap, in Iceland, and the Pasterze Glacier, in Austria, on the basis of satellite data from 1973-1987 and 1984-1990, respectively. Indications of a trend toward negative mass balance are noted. Nevertheless, while most of the world's small glaciers have been receding, some are advancing either due to local climate or the tidewater glacier cycle. 21 refs.

Hall, D.K.; Williams, R.S. Jr.; Bayr, K.J. (NASA, Goddard Space Flight Center, Greenbelt, MD (United States) USGS, Reston, VA (United States) Keene State College, NH (United States))

1992-03-01

395

Glacier recession in Iceland and Austria  

NASA Technical Reports Server (NTRS)

It has been possible to measure glacier recession on the basis of Landsat data, in conjunction with comparisons of the magnitude of recession of a glacier margin with in situ measurements at fixed points along the same margin. Attention is presently given to the cases of Vatnajokull ice cap, in Iceland, and the Pasterze Glacier, in Austria, on the basis of satellite data from 1973-1987 and 1984-1990, respectively. Indications of a trend toward negative mass balance are noted. Nevertheless, while most of the world's small glaciers have been receding, some are advancing either due to local climate or the tidewater glacier cycle.

Hall, Dorothy K.; Williams, Richard S., Jr.; Bayr, Klaus J.

1992-01-01

396

Light Iceland Glacier Recession 1973 to 2000  

NSDL National Science Digital Library

This animation shows glacier recesion at the Breidamerkurjokull glacier in Iceland. The data from 1973 is taken from Landsat 1 and the 2000 data is from Landsat 7. The Breidamerkurjokull glacier in Iceland has been measured by Landsat to be receding since 1973. The glacierologists in Iceland and here at NASAs Goddard Space Flight Center have measured the recession throughout the entire glacier and found different rates of recession in different areas. In genral, the glacier seems to be receding at about 2% annually. It is extremely controversial whether or not this recession is caused by global warming.

Lori Perkins

2001-04-09

397

Radiocarbon Dates Link Marine Incursion and Neoglacial Ice Terminus Advance With Tlingit Ethnohistory and Archeology in Lower Glacier Bay  

NASA Astrophysics Data System (ADS)

Radiocarbon dates from wood, organic sediments, and marine shells were collected from eroded beach terraces and upper beach sediments in the Beardslee Islands and Berg Bay in Glacier Bay National Park, Alaska. These provide a timetable for the the outwash plain construction and final advance of the Late Neoglacial glacier front over this outwash plain into lower Glacier Bay. On Kidney Island in the central Beardslee Islands, marine sediments containing Macoma baltica shells were deposited 4310 +/- 40 years BP. Outwash from advancing up-bay glaciers, buried these sediments and created terrestrial substrates upon which forests existed by 1630 +/- 60 BP and 1300 +/- 50 yrs BP. Final ice advance over this forested outwash plain occurred after 430 +/- 60 BP (1430 to 1510 AD) on Kidney Island. This ice arrived at the southern edge of Lester Island in Bartlett Cove after 370 +/- 50 BP (1440 to 1520 AD); preceding the arrival of George Vancouver in 1794 AD. In nearby Icy Straits, archeological investigations have yielded some of the oldest dates of human occupation in the region at 10,180 +/- 800 uncorrected years BP (Ackerman, 1968). In Glacier Bay's ethno-historically rich areas of Bartlett Cove, the Beardslee Islands and Berg Bay the Huna people have names for places and narratives that describe late Neoglacial landscapes. S' Shuyee is the "area at the end of the glacial mud", L'awsha Shakee Aan "town on top of the glacial sand dunes". There are accounts of villages overrun by surging glaciers, and a name for the bay Sit' eeti Geeyi that translates as "bay in place of the glacier". These dates provide linkage between the geological, archeological, and ethnohistorical evidence that chronicles the history of the Huna people in this dynamic glacier marine environment.

Connor, C. L.; Monteith, D.; Howell, W.; Strevelar, G.; Leirer, M.

2004-12-01

398

Climate-model induced differences in the 21st century global and regional glacier contributions to sea-level rise  

NASA Astrophysics Data System (ADS)

The large uncertainty in future global glacier volume projections partly results from a substantial range in future climate conditions projected by global climate models. This study addresses the effect of global and regional differences in climate input data on the projected twenty-first century glacier contribution to sea-level rise. Glacier volume changes are calculated with a surface mass balance model combined with volume-area scaling, applied to 89 glaciers in different climatic regions. The mass balance model is based on a simplified energy balance approach, with separated contributions by net solar radiation and the combined other fluxes. Future mass balance is calculated from anomalies in air temperature, precipitation and atmospheric transmissivity, taken from eight global climate models forced with the A1B emission scenario. Regional and global sea-level contributions are obtained by scaling the volume changes at the modelled glaciers to all glaciers larger than 0.1 km2 outside the Greenland and Antarctic ice sheets. This results in a global value of 0.102 0.028 m (multi-model mean and standard deviation) relative sea-level equivalent for the period 2012-2099, corresponding to 18 5 % of the estimated total volume of glaciers. Glaciers in the Antarctic, Alaska, Central Asia and Greenland together account for 65 4 % of the total multi-model mean projected sea-level rise. The projected sea-level contribution is 35 17 % larger when only anomalies in air temperature are taken into account, demonstrating an important compensating effect by increased precipitation and possibly reduced atmospheric transmissivity. The variability in projected precipitation and atmospheric transmissivity changes is especially large in the Arctic regions, making the sea-level contribution for these regions particularly sensitive to the climate model used. Including additional uncertainties in the modelling procedure and the input data, the total uncertainty estimate for the future projections becomes 0.063 m.

Giesen, Rianne H.; Oerlemans, Johannes

2013-12-01

399

Longitudinal surface structures (flowstripes) on Antarctic glaciers  

NASA Astrophysics Data System (ADS)

Longitudinal surface structures (''flowstripes'') are common on many glaciers but their origin and significance are poorly understood. In this paper we present observations of the development of these longitudinal structures from four different Antarctic glacier systems (the Lambert Glacier/Amery Ice Shelf area, outlet glaciers in the Ross Sea sector, ice-shelf tributary glaciers on the Antarctic Peninsula, and the onset zone of a tributary to the Recovery Glacier Ice Stream in the Filchner Ice Shelf area). Mapping from optical satellite images demonstrates that longitudinal surface structures develop in two main situations: (1) as relatively wide flow stripes within glacier flow units and (2) as relatively narrow flow stripes where there is convergent flow around nunataks or at glacier confluence zones. Our observations indicate that the confluence features are narrower, sharper, and more clearly defined features. They are characterised by linear troughs or depressions on the ice surface and are much more common than the former type. Longitudinal surface structures within glacier flow units have previously been explained as the surface expression of localised bed perturbations but a universal explanation for those forming at glacier confluences is lacking. Here we propose that these features are formed at zones of ice acceleration and extensional flow at glacier confluences. We provide a schematic model for the development of longitudinal surface structures based on extensional flow that can explain their ridge and trough morphology as well as their down-ice persistence.

Glasser, N. F.; Gudmundsson, G. H.

2011-11-01

400

The contribution of glacier melt to streamflow  

NASA Astrophysics Data System (ADS)

Ongoing and projected future changes in glacier volume and extent globally have led to concerns about the implications for water supplies. Glacier contributions to river discharge are not well known on a regional or global basis, nor are the populations at risk to future glacier changes. We estimate upper bounds on the fraction of river discharge attributable to glacier discharge on a monthly basis using a global hydrology model and glacier energy balance computations, and track this fraction through the global stream network. In general, our estimates of the fraction of river discharge attributable to glacier sources are lower than previously published values. Nonetheless, we estimate that globally 370 (140) million people live in river basins where glacier sources contribute at least 10% (25%) of river discharge on a seasonal basis. Most of this population is in the High Asia region.

Schaner, Neil; Voisin, Nathalie; Nijssen, Bart; Lettenmaier, Dennis P.

2012-09-01

401

The contribution of glacier melt to streamflow  

SciTech Connect

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

Schaner, Neil; Voisin, Nathalie; Nijssen, Bart; Lettenmaier, D. P.

2012-09-13

402

A possible Younger Dryas record in southeastern Alaska  

SciTech Connect

A stratigraphic record of climatic cooling equal in timing and severity to the Younger Dryas event of the North Atlantic region has been obtained form lacustrine sediments in the Glacier Bay area of southeastern Alaska. Fossil pollen show that a late Wisconsin pine parkland was replaced about 10,800 years ago by shrub- and herb-dominated tundra, which lasted until about 9,800 years ago. This vegetational change is matched by geochemical evidence for loss of organic matter from catchment soils and increased mineral erosion. If this event represents the Younger Dryas, then an explanation for a hemisphere-wide propagation of a North Atlantic climatic perturbation must be sought.

Engstrom, D.R.; Hansen, B.C.S.; Wright, H.E. Jr. (Univ. of Minnesota, Minneapolis (United States))

1990-12-07

403

Alaska geothermal bibliography  

SciTech Connect

The Alaska geothermal bibliography lists all publications, through 1986, that discuss any facet of geothermal energy in Alaska. In addition, selected publications about geology, geophysics, hydrology, volcanology, etc., which discuss areas where geothermal resources are located are included, though the geothermal resource itself may not be mentioned. The bibliography contains 748 entries.

Liss, S.A.; Motyka, R.J.; Nye, C.J. (comps.)

1987-05-01

404

ALASKA CRUISE SHIP INITIATIVE  

EPA Science Inventory

During the course of the annual vacation season, luxury cruise ships carrying up to 3000 passengers visit the coastal cities and small towns of Alaska. Alaska is the first state to impose regulations requiring such vessels to submit to inspection and monitoring of gray water and...

405

Educational Telecommunications for Alaska.  

ERIC Educational Resources Information Center

This telecommunications program planned and initiated by the Alaska Department of Education is designed to (1) provide basic communication capability to the state's 52 school district headquarters, (2) examine and report the results of making research and instructional information collections which exist outside Alaska available to educational

Alaska State Dept. of Education, Juneau. Office of Planning and Research.

406

Renewable Energy in Alaska  

SciTech Connect

This report examines the opportunities, challenges, and costs associated with renewable energy implementation in Alaska and provides strategies that position Alaska's accumulating knowledge in renewable energy development for export to the rapidly growing energy/electric markets of the developing world.

Not Available

2013-03-01

407

The Alaska Quaternary Center  

NSDL National Science Digital Library

This website illustrates the Alaska Quaternary Center's (at the University of Alaska, Fairbanks) commitment "to the promotion of interdisciplinary research and the enhancement of interdisciplinary instruction in Quaternary sciences." Users can view images of the field work and learn how to obtain quaternary data from the AQC Quaternary Research Geodatabase.

408

The current disequilibrium of North Cascade glaciers  

NASA Astrophysics Data System (ADS)

Three lines of evidence indicate that North Cascade (Washington, USA) glaciers are currently in a state of disequilibrium. First, annual balance measured on nine glaciers yields a mean cumulative balance for the 1984-2004 period of -8.58 m water equivalent (w.e.), a net loss of ice thickness exceeding 9.5 m. This is a significant loss for glaciers that average 30-50 m in thickness, representing 18-32% of their entire volume.Second, longitudinal profiles completed in 1984 and 2002 on 12 North Cascade glaciers confirm this volume change indicating a loss of -5.7 to -6.3 m in thickness (5.0-5.6 m w.e.) between 1984 and 2002, agreeing well with the measured cumulative balance of -5.52 m w.e. for the same period. The change in thickness on several glaciers has been equally substantial in the accumulation zone and the ablation zone, indicating that there is no point to which the glacier can retreat to achieve equilibrium. Substantial thinning along the entire length of a glacier is the key indicator that a glacier is in disequilibrium.Third, North Cascade glacier retreat is rapid and ubiquitous. All 47 glaciers monitored are currently undergoing significant retreat or, in the case of four, have disappeared. Two of the glaciers where mass balance observations were begun, Spider Glacier and Lewis Glacier, have disappeared. The retreat since 1984 of eight Mount Baker glaciers that were all advancing in 1975 has averaged 297 m. These observations indicate broad regional continuity in glacial response to climate.

Pelto, Mauri S.

2006-03-01

409

Wildlife Biologist Delta Junction, Alaska  

E-print Network

Wildlife Biologist Delta Junction, Alaska POSITION A Wildlife Biologist (Research Associate II). This position is located at Donnelly Training Area, Delta Junction, Alaska. ORGANIZATION CEMML is a research south of Delta Junction in Alaska and is located approximately 100 miles southeast of Fairbanks, Alaska

410

Alaska SeaLife Center  

NSDL National Science Digital Library

Located in Seward, Alaska, the Alaska SeaLife Center is a non-profit marine science facility dedicated to understanding and maintaining the integrity of the marine ecosystem of Alaska through research, rehabilitation and public education. The Center's research and rehabilitation facilities and naturalistic exhibits immerse visitors in the dynamic marine ecosystems of Alaska. Includes links to additional resources for students and teachers.

411

Alaska Airlines Operating costs and  

E-print Network

SYS-461 Alaska Airlines Operating costs and Productivity Daric Megersa #12;Airline Business Model-largest U.S. carrier Founded: 1932, in Anchorage, Alaska Hubs: Seattle (main hub); Anchorage, Alaska expense, interest capitalized and some other costs The trend shows that Alaska airlines has shown

412

Quaternary Glaciers of New Zealand  

Microsoft Academic Search

Located in the southwestern Pacific Ocean, New Zealand's record of Quaternary glaciations, preserved in landforms and near-surface deposits, begins at the margins of modern glaciers and extends outwards geographically and backwards in time, to the last glaciation and beyond. The record becomes increasingly fragmentary into the Middle and Early Pleistocene.

D. J. A. Barrell

2011-01-01

413

Icebergs and Glaciers: Unit Outlines  

NSDL National Science Digital Library

This article assembles free resources from the Icebergs and Glaciers issue of the Beyond Penguins and Polar Bears cyberzine into a unit outline based on the 5E learning cycle framework. Outlines are provided for Grades K-2 and 3-5.

Jessica Fries-Gaither

414

MOVEMENT OF WATER IN GLACIERS  

Microsoft Academic Search

A network of passages situated along three-grain intersections enables water to percolate through temperate glacier ice. The deformability of the ice allows the passages to expand and contract in response to changes in pressure, and melting of the passage walls by heat generated by viscous dissipation and carried by above-freezing water causes the larger passages gradually to increase in size

R. L. SHREVE

1972-01-01

415

Mountain Glaciers and Ice Caps  

USGS Publications Warehouse

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.

Ananichheva, Maria; Arendt, Anthony; Hagen, Jon-Ove; Hock, Regine; Josberger, Edward G.; Moore, R. Dan; Pfeffer, William Tad; Wolken, Gabriel J.

2011-01-01

416

UV - GLACIER NATIONAL PARK MT  

EPA Science Inventory

Brewer 134 is located in Glacier NP, measuring ultraviolet solar radiation. Irradiance and column ozone are derived from this data. Ultraviolet solar radiation is measured with a Brewer Mark IV, single-monochrometer, spectrophotometer manufactured by SCI-TEC Instruments, Inc. of ...

417

Jakobshavn Glacier Ice Flow (WMS)  

NSDL National Science Digital Library

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