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1

76 FR 69720 - NaturEner Rim Rock Wind Energy, LLC; Supplemental Notice That Initial Market-Based Rate Filing...  

Federal Register 2010, 2011, 2012, 2013

...Commission [ Docket No. ER12-295-000] NaturEner Rim Rock Wind Energy, LLC; Supplemental Notice That Initial Market-Based...the above-referenced proceeding of NaturEner Rim Rock Wind Energy, LLC's application for market-based rate...

2011-11-09

2

78 FR 26770 - NaturEner Wind Watch, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...  

Federal Register 2010, 2011, 2012, 2013

...Commission [Docket No. ER13-1368-000] NaturEner Wind Watch, LLC; Supplemental Notice That Initial Market-Based Rate...notice in the above-referenced proceeding of NaturEner Wind Watch, LLC's application for market-based rate authority,...

2013-05-08

3

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; Mifflin, Houghton

4

Glacier winds in the Rongbuk Valley, north of Mount Everest: 1. Meteorological modeling with remote sensing data  

NASA Astrophysics Data System (ADS)

Persistent glacier winds blowing from noon to midnight in summer are present in the Rongbuk Valley, north of Mount Everest, with a maximum speed of 10 m s-1 and a vertical thickness as high as 1 km. These glacier winds may bring upper level atmosphere ozone to the surface, having a significant impact on the atmospheric environment. Such phenomena may be typical of the Tibetan Plateau, where most high mountains are covered by snow or glacier ice throughout the year. The Advanced Regional Prediction Model was used to simulate the down-valley flows, using realistic topography but neglecting synoptic winds. The modeling results agree well with the observations obtained in June 2002, revealing that the glacier winds are thermal flows primarily driven by the along-valley temperature gradient between the colder air over the glacier surface and the warmer air over surface areas covered by rock debris, which maintains air advection along the Rongbuk Valley. Downslope winds over the glacier slopes, especially from the western valley side, and the West Rongbuk Glacier, were forced by their inertia farther down into the valley and would intensify the glacier winds. The narrowing of the Rongbuk Valley could also speed up the glacier winds. Sensitivity tests showed that the detailed distribution of the Rongbuk Glacier, delineated by data from the Enhanced Thematic Mapper Plus on Landsat 7, plays an important role in glacier winds development. The glacier winds could be much weaker in winter when the area is completely snow covered.

Song, Yu; Zhu, Tong; Cai, Xuhui; Lin, Weili; Kang, Ling

2007-06-01

5

Estimates of Glacier Mass Loss and Contributions to Streamflow: Wind River Range (Wyoming, USA)  

NASA Astrophysics Data System (ADS)

The Wind River Range (WRR) of Wyoming is host to approximately 63 glaciers. Extensive research has been conducted using remote imagery to estimate the area changes of these glaciers, with the goal of estimating the potential impacts of these changes on watershed streamflow. Results show that the glaciers were mostly in recession from 1966 to 2006 with glacier area losses estimated at 38%. Recent research efforts (paired watershed analysis), which supplement the results from the remote imagery analyses, evaluated late summer [July-August-September (JAS)] streamflows from glaciated and non-glaciated watersheds. The difference in observed JAS flows between glaciated and non-glaciated watersheds ranged between 8% and 23% and glaciers accounted for 23% to 54% of the observed late summer (JAS) flow in glaciated watersheds. This was primarily attributed to the glaciers decelerating the snowmelt runoff through internal storage/delayed release of liquid water and, to a lesser extent, the loss of glacier mass. However, no estimates were made as to what percentage of late summer streamflow is attributed to glacier mass (volume) loss. Applying established empirical relationships between glacier area and volume, estimates of glacier volume loss and the contribution to late summer streamflow were estimated for two glaciated watersheds of the WRR, the Upper Green River basin (west slope) and Bull Lake Creek basin (east slope). The results show that glacier mass contributes 2% to 8% of late summer streamflow resulting in estimated glacier losses of 0.4 to 0.7 meters per year from 1966 to 2006.

Tootle, G. A.; Marks, J.; Kerr, G.

2011-12-01

6

Glacier winds in the Rongbuk Valley, north of Mount Everest: 1. Meteorological modeling with remote sensing data  

Microsoft Academic Search

Persistent glacier winds blowing from noon to midnight in summer are present in the Rongbuk Valley, north of Mount Everest, with a maximum speed of 10 m s-1 and a vertical thickness as high as 1 km. These glacier winds may bring upper level atmosphere ozone to the surface, having a significant impact on the atmospheric environment. Such phenomena may

Yu Song; Tong Zhu; Xuhui Cai; Weili Lin; Ling Kang

2007-01-01

7

Glacier winds in the Rongbuk Valley, north of Mount Everest: 2. Their role in vertical exchange processes  

Microsoft Academic Search

High ozone concentrations, combined with low humidity and strong, persistent glacier winds, were found at the surface of Rongbuk Valley, north of Mount Everest, with sharply increased ozone concentrations in their vertical profiles. Glacier winds and their roles in vertical exchange of the atmosphere were investigated numerically to understand the phenomena. A Lagrangian particle dispersion model was used to carry

Xuhui Cai; Yu Song; Tong Zhu; Weili Lin; Ling Kang

2007-01-01

8

The contribution of glacier melt to stream flow in the Wind River Range, WY  

NASA Astrophysics Data System (ADS)

The Wind River Range (Wyoming) boasts the largest concentration of glaciers in the American Rockies, and together with adjacent mountain ranges is the source of several major river systems in the western US. Declines in the volume of these glaciers associated with recent climate warming are well documented. Such declines of alpine glaciers will reduce the amount of water available for agricultural and domestic use, especially in late summer and fall. The contribution of glacial melt to stream flow remains largely unquantified in many parts of the U.S., particularly in Wyoming. In this study, we estimated the fractional contribution of glacier melt water from Dinwoody Glacier to flow in Dinwoody Creek in the Wind River Range on diurnal, seasonal, and interannual time scales. The stable isotope composition of water from the Dinwoody Creek watershed was determined on spatially and temporally intensive scales in 2007 and 2008. Spatially intensive sampling took place in the summers of both years; water samples were collected from (1) above and below major confluences along Dinwoody Creek, from (2) Dinwoody Glacier, (3) rain water, and (4) snow. Stream samples were collected over the entire melt season using an automated stream sampler placed beside an unimpaired USGS gauging station low in the watershed. Glacial melt contributed significantly to stream flow during periods of peak daily discharge (afternoon) and during late summer peak flow (late-August). In 2008, snow persisted late into the summer, so snowmelt was the main source of streamflow in mid-summer (July). Disappearance of glaciers in this watershed will affect both ecosystem and human water supplies during the late summer period, particularly in years when snowfields do not persist late into the summer.

Cable, J. M.; Williams, D. G.; Bachman, S. A.

2008-12-01

9

Glacier variability (1966--2006) in the Wind River Range, Wyoming, U.S.A  

NASA Astrophysics Data System (ADS)

Spatial changes in glacier area for 44 glaciers in Wyoming's Wind River Range were estimated through a comparison of historic aerial photography from 1966 to 2006. The total surface area of the 44 glaciers was estimated to be 45.9 +/- 1.6 km2 in 1966 and 28.5 +/- 0.4 km 2 in 2006, a decrease of 42%. Volumes of individual glaciers during the 41-year period were estimated utilizing the Bahr et al. (1997) volume-area scaling technique. The total ice volume lost was estimated to be 0.89 +/- 0.4 km3, which equates to 4.2% and 9.7% of warm season (July-September) streamflow for the Green River and Bull Lake Creek watersheds for the 41-year period. It was also determined that the Dinwoody Creek watershed contributed 12.4% to warm season (July-September) streamflow during the 1989 to 2006 period. Glacial surface area was also estimated utilizing resampled aerial photography to assess the relationship between area and measurement scale. Aerial photographs were resampled to resolutions of 10 meter, 15 meter, 22.5 meter and 30 meter to represent other satellite image resolutions used for evaluating glacier boundaries. The results show a linear decrease of total glacier area as resolution decreases. When comparing 1 meter resolution to the 30 meter resolution photographs for 1966 and 2006 photos, an average decrease total glacier area of 5% was calculated. It was concluded that high-resolution aerial photography remains the preferred and most accurate source for measuring glacier characteristics.

Thompson, Derrick R.

10

Wind influence on snow depth distribution and accumulation over glaciers  

Microsoft Academic Search

In mountain regions wind is known to cause snow redistribution. While physically based models of snow redistribution have been developed for flat to gently rolling terrain, extension of these findings to steep terrain has been limited by the complexity of wind fields in such areas. In this study, we applied a nonhydrostatic and compressible atmospheric prediction model to steep alpine

R. Dadic; R. Mott; M. Lehning; P. Burlando

2010-01-01

11

Glacier winds in the Rongbuk Valley, north of Mount Everest: 2. Their role in vertical exchange processes  

NASA Astrophysics Data System (ADS)

High ozone concentrations, combined with low humidity and strong, persistent glacier winds, were found at the surface of Rongbuk Valley, north of Mount Everest, with sharply increased ozone concentrations in their vertical profiles. Glacier winds and their roles in vertical exchange of the atmosphere were investigated numerically to understand the phenomena. A Lagrangian particle dispersion model was used to carry out numerical experiments (forward-in-time simulations) and footprint analysis (backward-in-time simulations). The meteorological data inputs for these experiments were derived from the Advanced Regional Prediction System. Results showed that glacier winds may lead to significant downward transport of 1.5-2 km during the daytime from the northern slopes of Mount Everest. Glacier winds could advance down through the valley, with strong upward motions shown as a rolling up in front of their leading edge. Combining with upslope winds at two sidewalls of the valley or up-valley winds of tributaries, the lifting flows produced strong mixing of the atmosphere to a depth of approximately 3 km. Three-dimensional footprints derived from the particle dispersion model for the observational site, Rongbuk Monastery, clearly show influence from the mountainside of Mount Everest and from the southern part of the valley. The vertical extension of influence was as much as 2-3 km. Good correlation was found between the influence height and the ozone concentration. All the simulation results strongly indicate that the glacier winds and their related vertical exchange processes "pump down" ozone-rich air from upper levels to the surface of the valley.

Cai, Xuhui; Song, Yu; Zhu, Tong; Lin, Weili; Kang, Ling

2007-06-01

12

Man kan inte vlja och vraka bland naturens lagar  

E-print Network

1 Man kan inte välja och vraka bland naturens lagar Av Patrik Lindenfors (Från Humanisten rymden skulle ju all luft blåsa bort", kunde man till exempel påstå, med en argumentation som. Olika argument vägdes och värderades. Till slut nådde vetenskapen något som man kan kalla

Lindenfors, Patrik

13

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.

14

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 ...

Kio, Mr.

2008-11-06

15

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.

Sciencenow, Nova

16

Tropical Glaciers  

NASA Astrophysics Data System (ADS)

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

Fountain, Andrew

17

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

18

77 FR 56834 - Notice of Effectiveness of Exempt Wholesale Generator Status  

Federal Register 2010, 2011, 2012, 2013

...NaturEner Glacier Wind Energy 1, LLC... EG12-79-000 Flat Ridge 2 Wind Energy LLC........... EG12-80-000 Blue Sky East, LLC..................... EG12-81-000 Meadow Creek Project Company LLC..........

2012-09-14

19

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

20

Tropical Glaciers  

Microsoft Academic Search

The term ``tropical glacier'' calls to mind balmy nights and palm trees on one hand and cold, blue ice on the other. Certainly author Gabriel Garcia Marqez exploited this contrast in One Hundred Years of Solitude. We know that tropical fish live in warm, Sun-kissed waters and tropical plants provide lush, dense foliage populated by colorful tropical birds. So how

Andrew Fountain

2002-01-01

21

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

22

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.

Center, National S.

23

Columbia Glacier Terminus  

USGS Multimedia Gallery

View of Columbia Glacier's terminus as it enters the waters of Prince William Sound. Columbia Glacier is one of Alaska's many tidewater glaciers, and it has been the focus of numerous studies due to its unusually high rate of retreat. The glacier has retreated nearly 20 km (12.43 mi) since 1980. In ...

2010-07-14

24

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)

25

Glaciers: A water resource  

USGS Publications Warehouse

Most Americans have never seen a glacier, and most would say that glaciers are rare features found only in inaccessible, isolated wilderness mountains. Are they really so rare? Or are they really potentially important sources of water supply?

Meier, Mark; Post, Austin

1995-01-01

26

Online Glacier Photograph Database  

NSDL National Science Digital Library

NSIDC houses over 15,000 photographic prints of glaciers, taken both from the air and from the ground. These photographs constitute an important historical record, as well as a data collection of interest to those studying the response of glaciers to climate change. More than 3,000 glacier photos are online, and most of these glaciers are in the Rocky Mountains, the Pacific Northwest, and Alaska. In March 2006, a special collection, Long-Term Change Photograph Pairs, was added.

2006-01-01

27

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.

28

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.

29

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.

30

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

31

In Brief: Melting glaciers  

NASA Astrophysics Data System (ADS)

Glaciers in Patagonia and Alaska have been losing their mass, and for longer than glaciers elsewhere in the world, according to a 7 December report compiled by the United Nations Environment Programme (UNEP). Climate change is causing significant mass loss of glaciers in high mountains worldwide, notes the report, which calls for accelerated research, monitoring, and modeling of glaciers and snow and their role in water supplies. The report also highlights the vulnerability and exposure of people dependent upon [glacier-fed] rivers to floods, droughts and eventually shortages as a result of changes in the melting and freezing cycles linked with climate change and other pollution impacts, according to UNEP executive director Achim Steiner. For more information, visit http://www.grida.no/publications/highmountain-glaciers/.

Showstack, Randy; Tretkoff, Ernie

2010-12-01

32

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.

33

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

34

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.

Weisel, Frank

35

Recent changes of very small glaciers in the Swiss Alps  

NASA Astrophysics Data System (ADS)

Present knowledge about Alpine glaciers is not representative in terms of glacier size distribution. More than 80% of all Swiss glaciers are smaller than 0.5 km2 and hence belong to the class of very small glaciers. In the context of fast glacier wastage in the European Alps, the near-future development of the size class distribution will most probably be in favour of very small glaciers which will comparably increase in number. However, there has been little research carried out about very small glaciers so far. It is not clear whether findings and theoretical concepts elaborated for medium and large valley glaciers (> 3 km2) can be directly transferred to very small glaciers, whose accumulation patterns are, for instance, characteristically exceptional because winter precipitation is multiplied by wind drift and avalanching. The extent of glaciers in the European Alps has recently been mapped and inventoried spatio-temporally consistently. Nevertheless, such glacier outlines derived by satellite remote-sensing techniques are not accurate enough for the special case of investigating changes in very small glaciers. Therefore, glacier outlines are digitized manually using high-resolution (25 cm) orthophotographs covering the entire Swiss Alps acquired twice for every scene (both in the early and late noughties). In contrast to the known shortcomings of satellite remote-sensing based approaches, the margins of very small glaciers are (with few exceptions) clearly distinguishable on these orthophotos, even in shaded, snow- or debris-covered areas. For the eastern Swiss Alps (east of the rivers Reuss and Ticino), about one third of all glaciers has vanished since 1973. The total area presently still glacierized amounts to 140 km2, whereof very small glaciers cover only 25% but account for almost 90% of the total number of glaciers. Retreat rates are highest for very small glaciers but seem to be stabilizing or even decreasing since the early noughties, implying that many of them have retreated far back into shaded cirques and below headwalls. Downwasting and disintegration into different ice patches has become the dominant process of mass loss. Furthermore, we evaluate changes in ice volume over the last three decades for a large set of Swiss glaciers by combining the glacier outlines for the late noughties with a new precision DEM (swissALTI3D) for the same date with outlines and elevation information from around 1980. Ice volume changes are compared to measured and estimated total glacier ice volume in order to quantify relative volume losses over the last decades. Moreover, annual surface mass balance was determined for three very small glaciers complementing the analysis of recent changes in this glacier size class. Very small glaciers in the Swiss Alps show fast mass loss but the picture is not uniform both in space and time.

Fischer, Mauro; Huss, Matthias; Hoelzle, Martin

2013-04-01

36

Mendenhall Glacier Juneau, Alaska  

E-print Network

· · · · · · #12;V1 Mendenhall Glacier Juneau, Alaska 404 Alaskan Frontiers & Glaciers V1 PRSRTSTD U, rugged remote towns, amazing wildlife--this is Alaska, America's last frontier. Revel in its wild the Inside Passage along Canada's scenic western coast to Alaska and the small wilderness outpost

Raina, Ramesh

37

Columbia Glacier Calving  

USGS Multimedia Gallery

A dramatic iceberg calving from Columbia Glacier in Prince William Sound, Alaska. The iceberg has just broken free from under the water and shot to the surface, spinning towards the ice face. The ice cliff here is about 70 m (229.7 ft) tall. Icebergs are calved as stress fractures in the glacier mer...

2010-07-14

38

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.

Fries-Gaither, Jessica

39

Photographer Overlooking Columbia Glacier  

USGS Multimedia Gallery

Photographer Tad Pfeffer capturing images of Columbia Glacier in Prince William Sound, Alaska. He is looking down-glacier towards the ice front, which faces open water in the fjord. This open water is extremely rare, and has not happened again since 2005. The fjord is typically covered with iceberg ...

2010-07-14

40

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.

41

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.

42

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.

43

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.

Zvanut, Patti

2000-03-23

44

Bruggen Glacier, Chile  

NASA Technical Reports Server (NTRS)

The Expedition 3 crew of the International Space Station caught a rare glimpse of the massive ice fields and glaciers of Patagonia early in the afternoon on September 25, 2001. This part of the South American coast sees frequent storms and is often obscured from view by cloud cover. Bruggen Glacier in southern Chile is the largest western outflow from the Southern Patagonian Ice Field and, unlike most glaciers worldwide, advanced significantly since 1945. From 1945 to 1976, Bruggen surged 5 km across the Eyre Fjord, reaching the western shore by 1962 and cutting off Lake Greve from the sea. The glacier continued advancing both northward and southward in the fjord to near its present position before stabilizing. The growth covers a distance of more than 10 km north to south, adding nearly 60 square km of ice. Additional information on this and other Patagonian glaciers may be found at the following link: USGS - Historic Fluctuations of Outlet Glaciers from the Patagonian Ice Fields. Image ISS003-E-6061 was provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

2002-01-01

45

Isotopic composition of ice cores and meltwater from upper fremont glacier and Galena Creek rock glacier, Wyoming  

USGS Publications Warehouse

Meltwater runoff from glaciers can result from various sources, including recent precipitation and melted glacial ice. Determining the origin of the meltwater from glaciers through isotopic analysis can provide information about such things as the character and distribution of ablation on glaciers. A 9.4 m ice core and meltwater were collected in 1995 and 1996 at the glacigenic Galena Creek rock glacier in Wyoming's Absaroka Mountains. Measurements of chlorine-36 (36Cl), tritium (3H), sulphur-35 (35S), and delta oxygen-18 (??18O) were compared to similar measurements from an ice core taken from the Upper Fremont Glacier in the Wind River Range of Wyoming collected in 1991-95. Meltwater samples from three sites on the rock glacier yielded 36Cl concentrations that ranged from 2.1 ?? 1.0 X 106 to 5.8??0.3 X 106 atoms/l. The ice-core 36Cl concentrations from Galena Creek ranged from 3.4??0.3 X 105 to 1.0??0.1 X 106 atoms/l. Analysis of an ice core from the Upper Fremont Glacier yielded 36Cl concentrations of 1.2??0.2 X 106 and 5.2??0.2 X 106 atoms/l for pre- 1940 ice and between 2 X 106 and 3 X 106 atoms/l for post-1980 ice. Purdue's PRIME Lab analyzed the ice from the Upper Fremont Glacier. The highest concentration of 36Cl in the ice was 77 ?? 2 X 106 atoms/l and was deposited during the peak of atmospheric nuclear weapons testing in the late 1950s. This is an order of magnitude greater than the largest measured concentration from both the Upper Fremont Glacier ice core that was not affected by weapons testing fallout and the ice core collected from the Galena Creek rock glacier. Tritium concentrations from the rock glacier ranged from 9.2??0.6 to 13.2??0.8 tritium units (TU) in the meltwater to -1.3??1.3 TU in the ice core. Concentrations of 3H in the Upper Fremont Glacier ice core ranged from 0 TU in the ice older than 50 years to 6-12 TU in the ice deposited in the last 10 years. The maximum 3H concentration in ice from the Upper Fremont Glacier deposited in the early 1960s during peak weapons testing fallout for this isotope was 360 TU. One meltwater sample from the rock glacier was analyzed for 35S with a measured concentration of 5.4??1.0 millibecquerel per liter (mBeq/l). Modern precipitation in the Rocky Mountains contains 35S from 10 to 40 mBeq/L. The ??18O results in meltwater from the Galena Creek rock glacier (-17.40??0.1 to -17.98??0.1 per mil) are similar to results for modern precipitation in the Rocky Mountains. Comparison of these isotopic concentrations from the two glaciers suggest that the meltwater at the Galena Creek site is composed mostly of melted snow and rain that percolates through the rock debris that covers the glacier. Additionally, this water from the rock debris is much younger (less than two years) than the reported age of about 2000 years for the subsurface ice at the mid-glacier coring site. Thus the meltwater from the Galena Creek rock glacier is composed primarily of melted surface snow and rain water rather than melted glacier ice, supporting previous estimates of slow ablation rates beneath the surface debris of the rock glacier.

DeWayne, Cecil L.; Green, J.R.; Vogt, S.; Michel, R.; Cottrell, G.

1998-01-01

46

Solid precipitation on a tropical glacier in Bolivia measured with an ultrasonic depth gauge  

E-print Network

Solid precipitation on a tropical glacier in Bolivia measured with an ultrasonic depth gauge Jean´veloppement, La Paz, Bolivia Received 24 April 2002; revised 6 June 2002; accepted 6 June 2002; published 10 the equilibrium line of the Zongo glacier (2.4 km2 ), Bolivia (16°S). Study of the influence of wind, air

Berthier, Etienne

47

Late Pleistocene and Holocene paleoclimate and alpine glacier fluctuations recorded by high-resolution grain-size data from an alpine lake sediment core, Wind River Range, Wyoming, USA  

NASA Astrophysics Data System (ADS)

Varved lake sediments, which provide ideal high-resolution climate proxies, are not commonly available in many geographic areas over long time scales. This paper utilizes high-resolution grain-size analyses (n = 1040) from a 520-cm long sediment core from Lower Titcomb Lake (LTL), which lies just outside the type Titcomb Basin (TTB) moraines in the Wind River Range, Wyoming. The TTB moraines lie between Lower Titcomb Lake and Upper Titcomb Lake (UTL), about 3 km beyond, and 200 m lower than the modern glacier margin and Gannett Peak (Little Ice Age) moraines in the basin. Based on cosmogenic exposure dating, the TTB moraines are believed to be Younger Dryas (YD) age (Gosse et al., 1995) and lie in a geomorphic position similar to several other outer cirque moraines throughout the western American Cordillera. Until recently, many of these outer cirque moraines were believed to be Neoglacial age. The sediment core discussed here is one of five obtained from the two Titcomb Lakes, but is by the far the longest with the oldest sediment depositional record. Two AMS radiocarbon ages from the 445- and 455-cm core depths (about 2% loss on ignition, LOI) suggest that the lake basin may have been ice-free as early as 16.1 or even 16.8 cal 14C kyr, consistent with 10Be and 26Al exposure ages from boulders and bedrock surfaces outside the TTB moraines. The 257-cm depth in the core marks an abrupt transition from inorganic, sticky gray silt below (<1% LOI) to more organic, less sticky, light brown silt above (4-10% LOI). Eight AMS radiocarbon ages on bulk sediment and macrofossils date the transition to about 11.6 cal 14C kyr. Thus, sampling resolution above the transition is about 22.57 yr and below the transition is about 12.56 yr, consistent with a decreased sediment accumulation rate in LTL when Younger Dryas ice pulled back from the TTB moraines opening up UTL as a sediment depositional basin. The presented high-resolution grain size record reveals amplitudes and other structural features similar to delta 18O records from deep-lake ostracods in southern Germany, the Greenland ice core record, and speleothems in China. Major increases in the 2 - 8 m grain size fraction indicative of increased glacier rock flour production between the 257 and 466 cm core depths appear to be roughly correlative with the YD-Allerd-Blling-Meiendorf-Heinrich 1 climate events recognized in other terrestrial records and Northern Atlantic Ocean marine cores, but provide much higher resolution than most of those records from a climate-sensitive alpine region in North America.

Thompson Davis, P.; Machalett, Bjrn; Gosse, John

2013-04-01

48

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

49

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

50

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

51

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

52

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

53

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

54

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.

Wittman, Stephen

1998-04-01

55

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.

Nelson, Stephen

56

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.

Landis, Carol

57

Glacier Recession Prepared by Joni L. Kincaid  

E-print Network

North America Australia South America Africa #12;Some Existing Glacier Records Although researchers have and Social Science Program (AGSSS) Department of Geography, Texas A&M University Contact info: Joni Kincaid://glaciers.pdx.edu/GlacierTimeline/GlacierTimeline.html, 2006 #12;South Cascade Glacier North Cascades Range, Washington �Western aspect (faces west) �Median

58

Mt. Kilimanjaro's Receding Glaciers  

NASA Technical Reports Server (NTRS)

Mt. Kilimanjaro (Tanzania), the highest point in all Africa, was photographed by the crew of Space Shuttle mission STS-97 on December 2, 2000 (STS097-701-17). Kilimanjaro (Kilima Njaro or 'shining mountain' in Swahili) is capped by glaciers on its southern and southwestern flanks. The glaciers and snow cap covered a far greater area ten years prior to the view above. Compare the photograph above with a photograph of Kilimanjaro taken in November 1990 by the Space Shuttle mission STS-38 crew. Shuttle photograph provided by the Earth Sciences and Image Analysis Laboratory, Johnson Space Center. Additional photographs taken by astronauts and cosmonauts can be viewed via the NASA - JSC Gateway to Astronaut Photography of Earth.

2002-01-01

59

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.

60

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.

61

Muir Glacier in Glacier Bay National Monument 1950  

USGS Multimedia Gallery

This August 1950 photo documents the significant changes that occurred during the 9 years between photographs A and B. Muir Glacier has retreated more than 2 miles, exposing Muir Inlet, and thinned 340 feet or more. However, it still is connected with tributary Riggs Glacier....

62

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.

63

Mass balance modelling of a debris cover glacier: the case study of Miage Glacier, Italy  

NASA Astrophysics Data System (ADS)

The growing interest in the response of glaciers to a changing climate has put large attention on the development of models of glaciers response, and mass balance models in particular, and efforts are been made to improve their accuracy and predictive skills. A key component that is receiving increasing attention is the role played by debris cover on the response of glaciers. Thin layers of debris enhance melt by increasing absorption of shortwave radiation, while thicker covers reduce melt by insulating it. This has an effect on the surface energy balance, melt rates under debris, runoff production, mass balance and ultimately glacier flow. An accurate representation of the effect of debris seems therefore important, also in view of the significant increase of the debris cover extent over glaciers associated to a warming climate. Distributed debris energy-balance (EB) models have been recently developed to account for the melt rate enhancing/reduction due to a thin/thick debris layer, respectively. Application of EB models at the glacier and regional scale however is associated with an increase of computational efforts and large uncertainties related to the spatial changes in the debris cover properties (thickness and conductivity) as well as extrapolation of the input meteorological data such as wind, temperature and radiative fluxes. In this paper we present a model for simulations of past and future mass balance of debris covered glaciers that relies on more limited input data than required by a full EB model. The model is tested against simulations from an EB model. The new debris enhanced temperature-index model (DETI) accounts for the debris thickness feedback (Ostrem curve) through a parameterisation that includes variable debris thickness. The model is developed and then used for continuous simulations on the extensively debris-covered Miage Glacier, Italy. First, we run the distributed debris energy balance model for the ablation season 2005, when all the meteorological variables required as input to the physically based approach are available. To evaluate the performance of the empirical approach, we then compare the energy balance model outputs against the simulations of the new DETI model. The model outputs are also validated against ablation stake readings at 22 locations. Second, the empirical approach is run for the period 2005-2011 and continuous time series of glacier mass balance are compared to those obtained with the same empirical approach with simple reduction coefficients. Accumulation is modelled by spatially distributing precipitation with a gradient and accounting for redistribution of snow by gravity. Our main result is that an empirical approach accounting for the warming/insulating effect as a function of the debris thickness, as the DETI model, is able to simulate the glacier melt rate similarly to the more complex energy-balance model. We also show a clear difference with respect to the model with simple reduction parameters that does not take into account the variable effect of debris thickness.

Carenzo, Marco; Pellicciotti, Francesca; Mabillard, Johan; Reid, Tim; Brock, Ben; Burlando, Paolo

2013-04-01

64

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

65

Glacier monitoring at Popocatpetl volcano, Mexico: glacier shrinkage and possible causes  

Microsoft Academic Search

Glacier monitoring at Popocatpetl volcano, Mexico: glacier shrinkage and possible causes Glaciers in combination with volcanoes may represent an important hazard for human settlements. As Popocatpetl volcano is located in the vicinity of highly populated areas monitoring its glaciers is a vital part of the surveillance system of the volcano. Popocatpetl hosts two small glaciers that are monitored mainly by

Christian Huggel; Hugo Delgado

66

Water, Ice, and Meteorological Measurements at Xiao Dongkemadi Glacier, Central Tibetan Plateau, Balance Years from 2008 to 2011  

NASA Astrophysics Data System (ADS)

The glaciers on Tibetan Plateau play an important role in the catchment hydrology and climatology of this region. However, our knowledge with respect to water circulation in this remote area is scarce. Xiao Dongkemadi Glacier (XDG) is located near Tanggula Pass (the highest point on the Lanzhou-Lhasa road 5231ma.s.l.), central Tibetan Plateau (3304'N, 9204'E). Here, glacier mass balance and runoff directly reflects the glacier's response to local climate change, and glacier changes on the Tibetan Plateau strongly influence human welfare since water supplies in this arid/semi-arid region are predominantly from glacier melt. Due to its remote location, the mass balance of XDG has been monitored discontinuously since 1988 by the direct glaciological method. Recently, a more complete and fine-grained glacier monitoring system has been established on the cap of XDG, and is expected to make further contributions to research on the change of the cryospheric and climatic environment in the area. Winter snow accumulation and summer snow and ice ablation were measured at XDG, to estimate glacier mass-balance quantities for balance years from 2008 to 2011. Runoff from the basin containing the glacier and from an adjacent nonglacierized basin was gaged during all or parts of water years from 2008 and 2011. Air temperature, wind speed, precipitation, and incoming solar radiation were measured at selected locations on and near the glacier.

Xiaobo, He; Baisheng, Ye; Yongjian, Ding; Jian, Zhang

2013-04-01

67

Mechanical and hydrologic basis for the rapid motion of a large tidewater glacier. 1: Observations  

NASA Technical Reports Server (NTRS)

Measurements of glacier flow velocity and basal water pressure at two sites on Columbia Glacier, Alaska, are combined with meteorological and hydrologic data to provide an observational basis for assessing the role of water storage and basal water pressure in the rapid movement of this large glacier. During the period from July 5 to August 31, 1987, coordinated observations were made of glacier surface motion and of water level in five boreholes drilled to (or in one case near to) the glacier bed at two sites, 5 and 12 km from the terminus. Glacier velocities increased downglacier in this reach from about 4 m/d to about 7 m/d. Three types of time variation in velocity and other variables were revealed: (1) Diurnal fluctuation in water input/output, borehole water level, and ice velocity (fluctuation amplitude 5 to 8%); (2) Speed-up events in glacier motion (15-30% speed-up), lasting about three days, and ocurring at times of enhanced input of water, in some cases from rain and in others from ice ablation enhanced by strong, warm winds; (3) 'Extra-slowdown' events, in which, after a speed-up event, the ice velocity decreased in about 3 days to a level consistently lower than that prior to the speed-up event. All of the time variations were due, directly or indirectly, to variations in water input to the glacier.

Meier, Mark; Lundstrom, Scott; Stone, Dan; Kamb, Barclay; Engelhardt, Hermann; Humphrey, Neil; Dunlap, William W.; Fahnestock, Mark; Krimmel, Robert M.; Walters, Roy

1994-01-01

68

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

69

Widespread evidences of hoarfrost formation at a rock glacier in the Seckauer Tauern, Austria  

NASA Astrophysics Data System (ADS)

The mechanism of deep reversible air circulation (the so called "chimney effect" or "wind tube") is known to be a process of ground overcooling in the lower and deeper parts of porous sediments and related landforms such as scree slopes or intact and relict rock glaciers. Warm air outflow emerging from relatively small voids within these mostly coarse-grained sediment bodies is sometimes noticeable. However, easier to identify are associated phenomena such as snowmelt windows, snow cover depressions and hoarfrost formations. Generally, these indications for warm air outflow are found at the upper part of scree slopes or the rooting zone of rock glaciers. Here we present widespread field evidences of hoarfrost from the pseudo-relict Schneben Rock Glacier in the Seckauer Tauern Range, Austria located at E1440'26'' and N4722'31''. Herewith, a pseudo-relict rock glacier is defined as an intermediate rock glacier type between a relict and a climatic-inactive rock glacier, hence a relict rock glacier with locally isolated patches of permafrost. The rock glacier covers an area of about 0.11km2, ranges from ca. 1720 to 1905 m a.s.l., and consists predominantly of coarse-grained gneissic sediments with blocks up to a size of several cubic metres at the surface. In particular the lower part and some ridges in the central and upper part are covered by dwarf pines (pinus mugo) mirroring the flow structure of the previously active rock glacier. Isolated permafrost occurs presumably at the rooting zone of the rock glacier as indicated by evidences from a neighbouring rock glacier in a comparable setting. Field observations in November 2011 showed widespread occurrences of hoarfrost crystals growing around the funnel edge indicating the sublimation of vapour from warm funnels. Such hoarfrost sites were found at more than 50 single locations distributed over the entire rock glacier from the tongue to the rooting zone generally. The occurrence of hoarfrost can get classified into the following classes: (a) at foot slope positions, (b) along linear structures or depressions of the rock glacier, (c) below vegetation patches of dwarf pines, (d) at the interface between younger fine-grained sediments (derived from debris flows) and the coarse-grained former rock glacier surface, and finally (e) hoarfrost occurrence at the rock glacier body without any identifiable structure in the vicinity. Examples from these different hoarfrost classes are presented and discussed.

Kellerer-Pirklbauer, A.; Winkler, G.; Pauritsch, M.

2012-04-01

70

East Greenland Glacier Dynamics: An Interdisciplinary Study of Helheim Glacier  

Microsoft Academic Search

Our study of Helheim glacier was initiated in 2006 primarily to investigate the source of glacial earthquakes. Glacial earthquakes appear to be sensitive to climate parameters and could potentially serve as an \\

T. B. Larsen; M. Nettles; P. Elosegui; M. L. Andersen; A. P. Ahlstrm; J. L. Davis; J. D. Juan; G. Ekstrm; R. Forsberg; G. S. Hamilton; S. A. Khan; L. A. Stearns; L. Stenseng

2008-01-01

71

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

72

Middle Sister and Hayden Glacier  

USGS Multimedia Gallery

The North face of Middle Sister and Hayden Glacier, in Three Sisters Wilderness, Deschutes National Forest, Oregon. This Picture was taken while climbing Middle Sister. Middle Sister is also known as "Hope" and is an extinct stratovolcano....

2009-12-08

73

Life Cycle of a Glacier  

NSDL National Science Digital Library

The information on this site indicates that the life cycle of a glacier is more eventful than it appears. The site allows students to follow the journey of a single snowflake as it takes a ride through a glacier, a process that can take as much as 30,000 years to complete. It can be viewed as an interactive slide show or a single page of text and illustrations.

74

Winds  

NSDL National Science Digital Library

In this problem-based learning (PBL) scenario, students prepare a presentation for investors showing how their fishing company has a significant advantage because it locates upwelling zones and fishing areas using TRMM (Tropical Rainfall Measuring Mission) and other satellite data. Prior to launching the PBL, students learn about wind: the topics of air pressure, coriolis effect, upwelling and the role of differential heating on the atmosphere are explored in classroom demonstrations. Materials required include a beaker, coffee grounds, drinking straw, balloon, flashlight, and turntable. The resource includes teacher background information, glossary, assessment rubric, and an appendix introducing problem-based learning.

75

Assessing the potential contribution of blowing snow to the mass balance of glaciers in the Cariboo Mountains of British Columbia, Canada  

Microsoft Academic Search

The difference between snow accumulation and ice ablation determines the mass balance of glaciers, with snowfall as the dominant input. However, blowing snow is another important term in glacier mass balance. Blowing snow occurs when loose particles of snow at the surface are entrained by winds exceeding a certain threshold for transport. The role of blowing snow in the surface

A. Yadghar; B. Ainslie; P. L. Jackson; S. J. Dery

2009-01-01

76

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

77

Glacier Shrinkage and Effects on Alpine Hydrology  

NASA Astrophysics Data System (ADS)

Alpine glaciers cover an area of about 553 km2 in seven western states of the American West. With few exceptions, all glaciers have been shrinking over the past century and the rate of shrinkage has accelerated over the past few decades. Overall, smaller glaciers exhibit greatest shrinkage, relative to their size, compared to larger glaciers. Preliminary results from studies of glacier change in several national parks reveal the spatial pattern of glacier change. Glacier shrinkage, while contributing to global sea level change, has two important local effects. First, the net release of water from its storage in the frozen state enhances overall stream discharge. Second, the shrinking area of glaciers reduces their moderating effect on stream flow, particularly during late-summer and drought periods, and shifts peak runoff towards early summer. Consequently these alpine basins become more susceptible to future drought. In addition to these "clean" glaciers, debris-covered glaciers are probably important as well. Debris-covered glaciers melt at much slower rates than adjacent "clean" glaciers, with reduced daily variations in melt because of the insulation provided by the surface debris layer. The number and extent of debris-covered glaciers in the American west is not well known therefore their hydrological contribution is uncertain. However, if the number of debris-covered glaciers can be scaled from an inventory of those in the Rocky Mountain National Park (Achuff, 2003), the volume of debris-covered ice may be considerable. From an ecological perspective, the greatest effects are in the high alpine regions where glacier recession opens new areas for biological expansion, and where the hydrological dependence on glaciers is greatest. Lesser effects, related to suspended sediment loads, are felt well downstream (10's km) from glaciers.

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

2004-12-01

78

Ancient carbon from a melting glacier gives high 14C age in living pioneer invertebrates  

PubMed Central

Glaciers are retreating and predatory invertebrates rapidly colonize deglaciated, barren ground. The paradox of establishing predators before plants and herbivores has been explained by wind-driven input of invertebrate prey. Here we present an alternative explanation and a novel glacier foreland food web by showing that pioneer predators eat locally produced midges containing 21,000 years old ancient carbon released by the melting glacier. Ancient carbon was assimilated by aquatic midge larvae, and terrestrial adults achieved a radiocarbon age of 1040 years. Terrestrial spiders, harvestmen and beetles feeding on adult midges had radiocarbon ages of 3401100 years. Water beetles assumed to eat midge larvae reached radiocarbon ages of 11001200 years. Because both aquatic and terrestrial pioneer communities use ancient carbon, the term primary succession is questionable in glacier forelands. If our old invertebrates had been collected as subfossils and radiocarbon dated, their age would have been overestimated by up to 1100 years. PMID:24084623

Hgvar, Sigmund; Ohlson, Mikael

2013-01-01

79

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

80

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.

Research, National C.

81

Climatic controls of western U.S. glaciers at the last glacial maximum  

USGS Publications Warehouse

We use a nested atmospheric modeling strategy to simulate precipitation and temperature of the western United States 18,000 years ago (18 ka). The high resolution of the nested model allows us to isolate the regional structure of summer temperature and winter precipitation that is crucial to determination of the net mass balance of late-Pleistocene mountain glaciers in this region of diverse topography and climate. Modeling results suggest that climatic controls of these glaciers varied significantly over the western U.S. Glaciers in the northern Rocky Mountains existed under relatively cold July temperatures and low winter accumulation, reflecting anticyclonic, easterly wind flow off the Laurentide Ice Sheet. In contrast, glaciers that existed under relatively warmer and wetter conditions are located along the Pacific coast south of Oregon, where enhanced westerlies delivered higher precipitation than at present. Between these two groupings lie glaciers that were controlled by a mix of cold and wet conditions attributed to the convergence of cold air from the ice sheet and moisture derived from the westerlies. Sensitivity tests suggest that, for our simulated 18 ka climate, many of the glaciers exhibit a variable response to climate but were generally more sensitive to changes in temperature than to changes in precipitation, particularly those glaciers in central Idaho and the Yellowstone Plateau. Our results support arguments that temperature depression generally played a larger role in lowering equilibrium line altitudes in the western U.S. during the last glacial maximum than did increased precipitation, although the magnitude of temperature depression required for steady-state mass balance varied from 8-18??C. Only the Sierra Nevada glaciers required a substantial increase in precipitation to achieve steady-state mass balance, while glaciers in the Cascade Range existed with decreased precipitation.

Hostetler, S. W.; Clark, P. U.

1997-01-01

82

Rock glaciers of the Karakoram Himalaya and surrounding mountains, Inner Asia  

NASA Astrophysics Data System (ADS)

The transHimalayan upper Indus Basin contains thousands of rock glaciers. An exceptional diversity of forms and sizes exist, hitherto largely unresearched. They are in a well-defined elevation band across the mountains, usually less than 1400 m vertically, although total relief exceeds 7000 m. The zone varies from north to south, west to east, and with slope orientation. Interfluve elevations are primary constraints. Rock glaciers are absent below the lowest and the highest interfluves. They are uncommon in the highest Mustagh Karakoram, Nanga Parbat, and Hindu Kush where glacier ice blankets the elevations where they could develop. The heaviest concentrations occur in sub-ranges of intermediate elevation. A full spectrum of generative conditions is found; related to periglacial, talus, glacial, avalanche, wind-blown snow, and rock avalanche processes. Forms vary between north and south slopes; arid, rainshadowed and more snowy, humid valleys. Rock glacier complexes, where two or more join to create extensive lobes, may have tributaries with different source conditions. The larger examples are several kilometres in length,usually glacier-derived, evidently affected by Holocene glacial history, trans-glacial processes, and paraglacial instabilities. In lesser ranges, many smaller rock glaciers are associated with glacier-free cirques, glacially sculpted valley walls, and floors with abundant glacial deposits. In general, they are transitional in genesis, process, and spatially relative to glacierization, to the vertical cascade of moisture and debris, and climate change in the vertical. Their landscape roles include extensive fragmentation of drainage systems. Countless inactive rock glaciers occur, typically continuing below active ones.

Hewitt, Kenneth

2013-04-01

83

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

84

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

85

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....

86

Google Earth Tours of Glacier Change  

NSDL National Science Digital Library

A detailed Google Earth tour of glacier change over the last 50 years is given in class as an introduction. Students are then asked to select from a group of glaciers and create their own Google Earth tour exploring key characteristics and evident changes in that glacier.

Pelto, Mauri; Collection, Serc -.

87

Primer on glacier flows Christian Heining  

E-print Network

/drop of the seawater level - Glaciers are the biggest reservoir of fresh water on earth (74%) groundwater 20%, lakes (glacier surges) or to use the water of glaciers in power plants or for water supply for agriculture. 2 scales suggest a shallow water (thin film) approximation #12;

Sainudiin, Raazesh

88

Warm Oceans, Fast Glaciers: the connections  

Microsoft Academic Search

Over the last decade many outlet glaciers from the Greenland Ice Sheet have accelerated and thinned, and in a number of cases their termini have retreated. There is much in common from glacier to glacier that emerges as these changes are studied, yet the actual physical mechanisms remain unclear. One can show that the spatial patterns and timing of outlet

M. Truffer; M. A. Fahnestock; J. M. Amundson

2009-01-01

89

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

90

Mountain glaciers caught on camera  

NASA Astrophysics Data System (ADS)

Many glaciers around the world are melting, and new research is showing some of the dramatic details. Ulyana Horodyskyj, a graduate student at the Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado at Boulder, set up cameras to take time-lapse photographs of three lakes on a glacier in Nepal. This allowed her and her colleagues to see the supraglacial lake drain in real time for the first time, making it possible to estimate how much water was involved and how long it took for the lake to drain and refill. Horodyskyj said in a press conference at the AGU Fall Meeting that such observations of supraglacial lakes are valuable because in a warming climate, melting glaciers can lead to formation of supraglacial lakes.

Balcerak, Ernie

2011-12-01

91

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

92

Survey of glaciers in the northern Rocky Mountains of Montana and Wyoming; Size response to climatic fluctuations 1950-1996  

SciTech Connect

An aerial survey of Northern Rocky Mountain glaciers in Montana and Wyoming was conducted in late summer of 1996. The Flathead, Swan, Mission, and Beartooth Mountains of Montana were covered, as well as the Teton and Wind River Ranges of Wyoming. Present extent of glaciers in this study were compared to limits on recent USGS 15 and 7.5 topographic maps, and also from selected personal photos. Large cirque and hanging glaciers of the Flathead and Wind River Ranges did not display significant decrease in size or change in terminus position. Cirque glaciers in the Swan, Mission, Beartooth and Teton Ranges were markedly smaller in size; with separation of the ice body, growth of the terminus lake, or cover of the ice terminus with rockfalls. A study of annual snowfall, snowdepths, precipitation, and mean temperatures for selected stations in the Northern Rocky Mountains indicates no extreme variations in temperature or precipitation between 1950-1996, but several years of low snowfall and warmer temperatures in the 1980`s appear to have been sufficient to diminish many of the smaller cirque glaciers, many to the point of extinction. The disappearance of small cirque glaciers may indicate a greater sensitivity to overall climatic warming than the more dramatic fluctuations of larger glaciers in the same region.

Chatelain, E.E. [Valdosta State Univ., GA (United States)

1997-09-01

93

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

94

A database of worldwide glacier thickness observations  

NASA Astrophysics Data System (ADS)

One of the grand challenges in glacier research is to assess the total ice volume and its global distribution. Over the past few decades the compilation of a world glacier inventory has been well-advanced both in institutional set-up and in spatial coverage. The inventory is restricted to glacier surface observations. However, although thickness has been observed on many glaciers and ice caps around the globe, it has not yet been published in the shape of a readily available database. Here, we present a standardized database of glacier thickness observations compiled by an extensive literature review and from airborne data extracted from NASA's Operation IceBridge. This database contains ice thickness observations from roughly 1100 glaciers and ice caps including 550 glacier-wide estimates and 750,000 point observations. A comparison of these observational ice thicknesses with results from area- and slope-dependent approaches reveals large deviations both from the observations and between different estimation approaches. For glaciers and ice caps all estimation approaches show a tendency to overestimation. For glaciers the median relative absolute deviation lies around 30% when analyzing the different estimation approaches. This initial database of glacier and ice caps thickness will hopefully be further enlarged and intensively used for a better understanding of the global glacier ice volume and its distribution.

Grtner-Roer, I.; Naegeli, K.; Huss, M.; Knecht, T.; Machguth, H.; Zemp, M.

2014-11-01

95

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

96

GLIMS Glacier Database: Status and Challenges  

NASA Astrophysics Data System (ADS)

GLIMS (Global Land Ice Measurements from Space) is an international initiative to map the world's glaciers and to build a GIS database that is usable via the World Wide Web. The GLIMS programme includes 70 institutions, and 25 Regional Centers (RCs), who analyze satellite imagery to map glaciers in their regions of expertise. The analysis results are collected at the National Snow and Ice Data Center (NSIDC) and ingested into the GLIMS Glacier Database. The database contains approximately 80 000 glacier outlines, half the estimated total on Earth. In addition, the database contains metadata on approximately 200 000 ASTER images acquired over glacierized terrain. Glacier data and the ASTER metadata can be viewed and searched via interactive maps at http://glims.org/. As glacier mapping with GLIMS has progressed, various hurdles have arisen that have required solutions. For example, the GLIMS community has formulated definitions for how to delineate glaciers with different complicated morphologies and how to deal with debris cover. Experiments have been carried out to assess the consistency of the database, and protocols have been defined for the RCs to follow in their mapping. Hurdles still remain. In June 2008, a workshop was convened in Boulder, Colorado to address issues such as mapping debris-covered glaciers, mapping ice divides, and performing change analysis using two different glacier inventories. This contribution summarizes the status of the GLIMS Glacier Database and steps taken to ensure high data quality.

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

2008-12-01

97

Recent changes detected on two glaciers at the northern part of James Ross Island, Antarctica  

NASA Astrophysics Data System (ADS)

Antarctic Peninsula is one of the regions, which have been exposed to the most rapid warming of the Earth since 1950. Consequences of climate changes are clearly documented by recent disintegration of ice shelves on both sides of the Antarctic Peninsula as well as by the retreat of land-based glaciers. James Ross Island, located close to the northernmost tip of the Antarctic Peninsula, represents an excellent place to study changes in the glacier mass-balance and their sensitivity to a regional warming trend. Two different types of glaciers of the Ulu Peninsula, the Whisky Glacier and the Davies Dome have been studied. Multi-temporal remote sensing data (aerial photographs, Landsat MSS, TM and ETM+ and Aster satellite optical and thermal multispectral data) and field survey allowed detecting changes in extent (2-D) as well as calculating glacier mass-balance changes (3-D) for these two glaciers from 1977 to 2009. The Whisky Glacier is a well-delimited valley glacier located mostly below the local Equilibrium line altitude (ELA). The glacier with high-flow velocities is fed by an intensive snow accumulation caused by prevailing southwestern winds. The Whisky Glacier covers an area of 2.3 km2 and its altitude varies from 215 to 475 m a.s.l. The Davies Dome is a flat-bottom dome glacier. Significant parts of its surface are located above the ELA and limited flow velocities are characteristic for the most parts of its body. However, the Davies Dome has a single 500-700 m wide southwestern outlet flowing towards the Whisky Bay. The Davies Dome extends an area of 6.7 km2 and its altitude ranges from 0 to 514 m a.s.l. Both glaciers experienced massive extension of their ice tongues towards the Brandy Bay during the mid Holocene. Lateral moraines located in front of the both glaciers heading down to the left coast of the Brandy Bay document this event. According to the remote sensing data and field investigations both glaciers have retreated since 1977. Between 2006 and 2009 repeated mapping of the Davies Dome was carried out and the results showed that the largest retreat ranging from 10 to 20 m occurred in the NW flat part of the glacier. Digital elevation models calculated on bases of aerial stereo-photographs from 1979 and 2006 allowed us to define mass-balance changes of the studied glaciers. Ground Penetrating Radar measurements taken on both glaciers helped with mass-balance investigations, furthermore, made it possible to increase the accuracy of the 3-D models. Annual mass balance measurements on the Davies Dome indicated a mean ablation about 20 cm between 2006 and 2009. On the Whisky Glacier, a network of 20 ablation stakes was established just recently (February 2009). Therefore, another 3-year investigation is necessary to bring comparable results. Acknowledgments: This research has been undertaken within a framework of the project No. 205/09/1876 funded by the Czech Science Foundation and by the R & D project VaV SP II 1a9/23/07.

Nvlt, Daniel; Kopa?kov, Veronika; Lska, Kamil; Engel, Zbyn?k.

2010-05-01

98

Spatially heterogeneous wastage of Himalayan glaciers  

PubMed Central

We describe volumetric changes in three benchmark glaciers in the Nepal Himalayas on which observations have been made since the 1970s. Compared with the global mean of glacier mass balance, the Himalayan glaciers showed rapid wastage in the 1970s1990s, but similar wastage in the last decade. In the last decade, a glacier in an arid climate showed negative but suppressed mass balance compared with the period 1970s1990s, whereas two glaciers in a humid climate showed accelerated wastage. A mass balance model with downscaled gridded datasets depicts the fate of the observed glaciers. We also show a spatially heterogeneous distribution of glacier wastage in the Asian highlands, even under the present-day climate warming. PMID:21808042

Fujita, Koji; Nuimura, Takayuki

2011-01-01

99

Spatially heterogeneous wastage of Himalayan glaciers.  

PubMed

We describe volumetric changes in three benchmark glaciers in the Nepal Himalayas on which observations have been made since the 1970s. Compared with the global mean of glacier mass balance, the Himalayan glaciers showed rapid wastage in the 1970s-1990s, but similar wastage in the last decade. In the last decade, a glacier in an arid climate showed negative but suppressed mass balance compared with the period 1970s-1990s, whereas two glaciers in a humid climate showed accelerated wastage. A mass balance model with downscaled gridded datasets depicts the fate of the observed glaciers. We also show a spatially heterogeneous distribution of glacier wastage in the Asian highlands, even under the present-day climate warming. PMID:21808042

Fujita, Koji; Nuimura, Takayuki

2011-08-23

100

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

101

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 ...

102

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

103

Slow Surge of Trapridge Glacier  

NASA Astrophysics Data System (ADS)

Trapridge Glacier, Yukon, Canada, is a polythermal, soft-bedded surge-type glacier. As revealed by a 1951 aerial photograph, an important surge occurred in the 1940s, leaving the glacier heavily crevassed and at least 1 km downstream from the 1941 position. It is our conclusion that another surge, albeit far less dramatic, has been taking place over the last three decades and is now terminated. To quantify the changes in ice geometry, ground survey measurements were coupled with aerial photogrammetry to yield digital elevation models of the glacier from 1951 to present. For 1951, 1970, 1972, 1977 and 1981, years for which ground data are scarce or unavailable, DEMs were generated from stereographic analysis of aerial photographs. For the subsequent years, DEMs are obtained from ground survey data using our implementation of a Bayesian Kriging algorithm. For each year, the topography of the previous year is used as a background model and updated by the available survey data. This chain is initiated by the 1981 DEM obtained from aerial photogrammetry. Using exposed sections of the bed from the 1981 DEM and radar data, a map of the bed topography is obtained. Changes in the flow patterns are also investigated using an extended but variable array of flow markers. The results of this work indicate that the period from the previous surge to the present was characterized by two processes: 1) the deglaciation of the 1940s surge `receiving area' and 2) the slow advance of a mass wave from the upper reaches of the glacier. While it was previously believed that this mass reorganization was to precede a fast surge, it is now obvious that such a surge is not to happen. Ice velocity peaked at nearly 40 m/yr in the mid 1980s, fluctuated for the next 15 years and then dropped ca 2000 to reach ~10 m/yr in 2005. The bulge that formed in the 1980s at the transition between warm- and cold-based ice continued to propagate beyond the limits of the 1981 glacier. The glacier snout is currently ~200 m downstream from the 1981 terminus and not advancing. Together the DEMs and bed topography map enable us to characterize changes in the distribution and volume of ice, hydrological potential, and basal stress that accompanied the slow surge.

Frappe-Seneclauze, T.; Clarke, G. K.

2005-12-01

104

Quantifying Global Warming from the Retreat of Glaciers  

Microsoft Academic Search

Records of glacier fluctuations compiled by the World Glacier Monitoring Service can be used to derive an independent estimate of global warming during the last 100 years. Records of different glaciers are made comparable by a two-step scaling procedure: one allowing for differences in glacier geometry, the other for differences in climate sensitivity. The retreat of glaciers during the last

Johannes Oerlemans

1994-01-01

105

Phytoplankton biomass andphotosynthetic competency in the summertime Mertz Glacier Region of East Antarctica  

Microsoft Academic Search

Vertical profiles of water temperature, salinity, beam transmission, density, pressure, wind speed, wind direction, phytoplankton biomass (chlorophyll a (Chl a) plus phaeophytin a), andphotosynthetic competency (by fast repetition- rate fluorometry) are presentedfor the Mertz Glacier region, East Antarctica, for a 3-week periodd uring the austral summer 2000-2001. Injection of low-salinity water from the melting of the ice pack formeda shallow

Robert D. Vaillancourt; Sara Green

2003-01-01

106

Glaciers in the Rupal Valley (Nanga Parbat)  

NASA Astrophysics Data System (ADS)

The widely discussed controversy about Himalayan glacier changes instigated a current boom in studies on a regional scale. In contrast to often simplified assumptions of general and mostly rapid glacier retreat, recent studies show a more complex pattern with stable, advancing and retreating glaciers. Furthermore, changes of debris covered glaciers are discussed controversial. Due to the great vertical span and steep relief, large ice streams in the Himalaya and Karakoram are often primarily fed by avalanches. Their impact on glacier mass balances is often unconsidered in present studies. However, Hewitt (2014) highlighted the crucial role of snow and ice re-distribution by avalanches for Karakoram glaciers. He used a concept of glacier typology based on different nourishment processes introduced at the beginning of the 20th century. By using this concept, Hewitt classified large glaciers in order to identify the effect of avalanches on the mass balance, because many Karakoram glaciers show low down-wasting or even thickening processes described as the "Karakoram anomaly" (Hewitt 2005). Also in the Nanga Parbat region, the western corner of the High Himalaya, the topography is characterized by steep rock walls with vertical distances up to 4700 m. The debris covered glaciers reach down to 2920 m a.s.l. and are regularly fed by small and large avalanches. Our field based investigations show that the glaciers are characterized by small retreating rates since 1857, when Adolph Schlagintweit has mapped them for the first time; others such as the Raikot Glacier are fluctuating since 1934. Furthermore, the extent of down-wasting varies between different glaciers. By using multi-temporal satellite data, topographical maps, sketches and terrestrial photographs changes of glacier lengths were measured. In order to calculate the down-wasting rates, a digital elevation model (DEM) with a spatial resolution of 30x30 m was derived from the digitized contour lines of the topographic map of 1934 and compared to the SRTM-DEM. Furthermore, based on topographical parameters derived from the SRTM-DEM, the glaciers were classified, using Hewitt's concept. The area of steep rock walls and the ratio between accumulation and ablation zones were calculated for each glacier basin. References: Hewitt, K. 2005: The Karakoram anomaly? Glacier expansion and the 'elevation effect', Karakoram Himalaya. Mountain Research and Development 25 (4), S. 332-340 Hewitt, K. 2014: Glaciers of the Karakoram Himalaya: Glacial Environments, Processes, Hazards and Resources. Springer. Dordrecht.

Schmidt, Susanne; Nsser, Marcus

2014-05-01

107

Columbia Glacier in 1984: disintegration underway  

SciTech Connect

Columbia Glacier is a large, iceberg-calving glacier near Valdez, Alaska. The terminus of this glacier was relatively stable from the time of the first scientific studies in 1899 until 1978. During this period the glacier terminated partly on Heather Island and partly on a submerged moraine shoal. In December, 1978, the glacier terminus retreated from Heather Island, and retreat has accelerated each year since then, except during a period of anomalously low calving in 1980. Although the glacier has not terminated on Heather Island since 1978, a portion of the terminus remained on the crest of the moraine shoal until the fall of 1983. By December 8, 1983, that feature had receded more than 300 m from the crest of the shoal, and by December 14, 1984, had disappeared completely, leaving most of the terminus more than 2000 meters behind the crest of the shoal. Recession of the glacier from the shoal has placed the terminus in deeper water, although the glacier does not float. The active calving face of the glacier now terminates in seawater that is about 300 meters deep at the glacier centerline. Rapid calving appears to be associated with buoyancy effects due to deep water at the terminus and subglacial runoff. 12 refs., 10 figs.

Meier, M.F.; Rasmussen, L.A.; Miller, D.S.

1985-01-01

108

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

109

Recent acceleration of Thwaites Glacier  

NASA Technical Reports Server (NTRS)

The first velocity measurements for Thwaites Glacier were made by R. J. Allen in 1977. He compared features of Thwaites Glacier and Iceberg Tongue on aerial photography from 1947 and 1967 with 1972 Landsat images, and measured average annual displacements of 3.7 and 2.3 km/a. Using his photogrammetric experience and taking into consideration the lack of definable features and the poor control in the area, he estimated an average velocity of 2.0 to 2.9 km/a to be more accurate. In 1985, Lindstrom and Tyler also made velocity estimates for Thwaites Glacier. Using Landsat imagery from 1972 and 1983, their estimates of the velocities of 33 points ranged from 2.99 to 4.02 km/a, with an average of 3.6 km/a. The accuracy of their estimates is uncertain, however, because in the absence of fixed control points, they assumed that the velocities of icebergs in the fast ice were uniform. Using additional Landsat imagery in 1984 and 1990, accurate coregistration with the 1972 image was achieved based on fixed rock points. For the period 1972 to 1984, 25 points on the glacier surface ranged in average velocity from 2.47 to 2.76 km/a, with an overall average velocity of 2.62 +/- 0.02 km/a. For the period 1984 to 1990, 101 points ranged in velocity from 2.54 to 3.15 km/a, with an overall average of 2.84 km/a. During both time periods, the velocity pattern showed the same spatial relationship for three longitudinal paths. The 8-percent acceleration in a decade is significant. This recent acceleration may be associated with changes observed in this region since 1986. Fast ice melted and several icebergs calved from the base of the Iceberg Tongue and the terminus of Thwaites Glacier. However, as early as 1972, the Iceberg Tongue had very little contact with the glacier.

Ferrigno, J. G.

1993-01-01

110

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

NASA Astrophysics Data System (ADS)

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

Mayer, H.; Herzfeld, U. C.

2003-12-01

111

Simulation of glacier hydrology: how much information do we need?  

NASA Astrophysics Data System (ADS)

For the management of water resources as well as for climate change impact predictions, the hydrologic cycle of high mountainous catchments is frequently simulated with very simple precipitation-discharge models representing the snow accumulation and ablation behavior of a very complex environment with a set of lumped equations accounting only for altitudinal temperature and precipitation differences. These models are often calibrated so that the model reproduces as closely as possible a series of observed discharge measurements. The question inevitably arises whether long term predictions of such a calibrated model are actually reliable, since knowing that a model performs well for historic situations does by no means imply that it will perform well for future, considerably modified catchment conditions. A first, although not sufficient step to answer this question, is investigating whether with such a model, we are "getting the right answers for the right reasons". In glacierized catchments, this would for example imply that a precipitation-runoff model should not just mimic observed discharge but also reproduce the glacier mass balance. In this study, we show how much observed information we need to reliably calibrate a hydrological model for a high mountainous catchment. Based on glacio-hydrological data from the Rhone glacier catchment, we analyze how well a simple conceptual precipitation-runoff model can reproduce seasonal glacier mass balance data and in a second step, how much information is required to achieve a reliable model calibration. Here, we focus on the question whether observed discharge is sufficient or whether we need annual or even seasonal glacier mass balance data. For this particular catchment, a detailed reproduction of observed seasonal balances requires a modification of the snow accumulation and ablation module. The model only accounts for altitudinal differences of the meteorological conditions and e.g. not for wind drift or exposition. As our results show, introducing seasonal accumulation and ablation parameters is sufficient to enable this simple model to reproduce observed seasonal balances and annual net balances. Furthermore, our results suggest that calibrating the hydrological model exclusively on discharge can lead to wrong representations of the intra-annual accumulation and ablation processes and, thus, to a bias in long term glacier mass balance simulations. Adding only a few annual net balance observations considerably reduces this bias. Calibrating exclusively on annual net balance data can, in turn, lead to wrong seasonal mass balance simulations. Even if these results are case study specific, our conclusions give valuable new insights into the benefit of different types of observations for snow modeling in high alpine catchments. The developed methods of model calibration on sparse data of snow accumulation and ice ablation can easily be transposed to similar modeling settings.

Schaefli, Bettina; Huss, Matthias

2010-05-01

112

Mapping Svalbard Glaciers with the Cryowing Uas  

NASA Astrophysics Data System (ADS)

The remoteness of most Svalbard glaciers makes it difficult to perform regular in situ monitoring, especially in the melting season. Terminus areas (into the sea) and crevassed areas are in practice only accessible from the air. In this paper, first investigations on the feasibility of UAS based 3D measurements of glacier elevation is performed. The results show that UAS can be a valuable tool for glacier measurements in remote areas like Svalbard, where the only real alternative to measure glacier elevation in the ablation zone during the melt season is by manned aircraft. Imagery from repeated observations within a few days can be used to estimate dynamic mass loss rates when coupled to 3D modeling and feature tracking. Retrieval of these data is valuable, especially for glaciers terminating in the sea and surging glaciers.

Solb, S.; Storvold, R.

2013-08-01

113

HIGH ICE, Continuation Some glacier image analysis capabilities  

E-print Network

, 20002000 lake outlines from Benn and others, 2000 #12;ASTER Level 2 relative DEM over western Axel Heiberg Island glaciers ASTER 3NASTER 3N #12;View from top ofView from top of Llewellyn GlacierLlewellyn Glacier

114

Spatial and temporal variability of air temperature on a melting glacier: Atmospheric controls, extrapolation methods and their effect on melt modeling, Juncal Norte Glacier, Chile  

NASA Astrophysics Data System (ADS)

Temperature data from three Automatic Weather Stations and twelve Temperature Loggers are used to investigate the spatiotemporal variability of temperature over a glacier, its main atmospheric controls, the suitability of extrapolation techniques and their effect on melt modeling. We use data collected on Juncal Norte Glacier, central Chile, during one ablation season. We examine temporal and spatial variability in lapse rates (LRs), together with alternative statistical interpolation methods. The main control over the glacier thermal regime is the development of a katabatic boundary layer (KBL). Katabatic wind occurs at night and in the morning and is eroded in the afternoon. LRs reveal strong diurnal variability, with steeper LRs during the day when the katabatic wind weakens and shallower LRs during the night and morning. We suggest that temporally variable LRs should be used to account for the observed change. They tend to be steeper than equivalent constant LRs, and therefore result in a reduction in simulated melt compared to use of constant LRs when extrapolating from lower to higher elevations. In addition to the temporal variability, the temperature-elevation relationship varies also in space. Differences are evident between local LRs and including such variability in melt modeling affects melt simulations. Extrapolation methods based on the spatial variability of the observations after removal of the elevation trend, such as Inverse Distance Weighting or Kriging, do not seem necessary for simulations of gridded temperature data over a glacier.

Petersen, L.; Pellicciotti, F.

2011-12-01

115

Modeling of glacier bed topography from glacier outlines, central branch lines, and a DEM  

Microsoft Academic Search

Due to the expected future climate change, glacier ice as a resource will be further diminished and its sea-level rise contribution further increased. A key for a more accurate determination of future glacier evolution is to improve our currently sparse knowledge on glacier bedrock topography. Here, we present a simplified method implemented in a geographic information system to approximate subglacial

Frank Paul; Andreas Linsbauer

2012-01-01

116

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

117

Glacier Inventory Update at Popocatpetl volcano, Mexico by Digital Photogrammetry: Documentation of Glacier Extinction  

Microsoft Academic Search

Monitoring of glaciers at volcanoes at inter-tropical latitudes is very important for several reasons. Glacier fluctuations provide insights to the climate change in these latitudes. Also, inventory of glaciers at volcanoes allows evaluation of hazards during eruptive periods. However, glaciological work is a difficult task during eruptions and becomes hazardous to researchers. In this context, a tool such as digital

P. Julio-Miranda; H. Delgado-Granados; S. Ortega-del-Valle; C. Huggel

2001-01-01

118

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 ICESat-1 and NASA aircraft altimeter overflights spanning 2002­ 09 indicate that a region of lower Crane is not seen. Bathymetry in Crane Glacier fjord reveals a series of flat-lying, formerly subglacial deeps

Paris-Sud XI, Université de

119

The GAMDAM Glacier Inventory: a quality controlled inventory of Asian glaciers  

NASA Astrophysics Data System (ADS)

We present a new glacier inventory for the high mountain Asia named "Glacier Area Mapping for Discharge from the Asian Mountains" (GAMDAM). Glacier outlines were delineated manually using more than 226 Landsat ETM+ scenes from the period 1999-2003, in conjunction with a digital elevation model (DEM) and high-resolution Google Earth imagery. Geolocations are consistent between the Landsat imagery and DEM due to systematic radiometric and geometric corrections made by the United States Geological Survey. We performed repeated delineation tests and rigorous peer review of all scenes used in order to maintain the consistency and quality of the inventory. Our GAMDAM Glacier Inventory (GGI) includes 82776 glaciers covering a total area of 87507 13126 km2 in the high mountain Asia. Thus, our inventory represents a greater number (+4%) of glaciers but significantly less surface area (-31%) than a recent global glacier inventory (Randolph Glacier Inventory, RGI). The employed definition of the upper boundaries of glaciers, glacier recession since the 1970s, and misinterpretation of seasonal snow cover are likely causes of discrepancies between the inventories, though it is difficult to evaluate these effects quantitatively. The GGI will help improve the temporal consistency of the RGI, which incorporated glacier outlines from the 1970s for the Tibetan Plateau, and will provide new opportunities to study Asian glaciers.

Nuimura, T.; Sakai, A.; Taniguchi, K.; Nagai, H.; Lamsal, D.; Tsutaki, S.; Kozawa, A.; Hoshina, Y.; Takenaka, S.; Omiya, S.; Tsunematsu, K.; Tshering, P.; Fujita, K.

2014-06-01

120

Antarctica: measuring glacier velocity from satellite images  

SciTech Connect

Many Landsat images of Antarctica show distinctive flow and crevasse features in the floating part of ice streams and outlet glaciers immediately below their grounding zones. Some of the features, which move with the glacier or ice stream, remain visible over many years and thus allow time-lapse measurements of ice velocities. Measurements taken from Landsat images of features on Byrd Glacier agree well with detailed ground and aerial observations. The satellite-image technique thus offers a rapid and cost-effective method of obtaining average velocities, to a first order of accuracy, of many ice streams and outlet glaciers near their termini.

Lucchitta, B.K.; Ferguson, H.M.

1986-11-28

121

Antarctica: Measuring glacier velocity from satellite images  

USGS Publications Warehouse

Many Landsat images of Antarctica show distinctive flow and crevasse features in the floating part of ice streams and outlet glaciers immediately below their grounding zones. Some of the features, which move with the glacier or ice stream, remain visible over many years and thus allow time-lapse measurements of ice velocities. Measurements taken from Landsat images of features on Byrd Glacier agree well with detailed ground and aerial observations. The satellite-image technique thus offers a rapid and cost-effective method of obtaining average velocities, to a first order of accuracy, of many ice streams and outlet glaciers near their termini.

Lucchitta, B. K.; Ferguson, H. M.

1986-01-01

122

Internationally coordinated glacier monitoring: strategy and datasets  

NASA Astrophysics Data System (ADS)

Internationally coordinated monitoring of long-term glacier changes provide key indicator data about global climate change and began in the year 1894 as an internationally coordinated effort to establish standardized observations. Today, world-wide monitoring of glaciers and ice caps is embedded within the Global Climate Observing System (GCOS) in support of the United Nations Framework Convention on Climate Change (UNFCCC) as an important Essential Climate Variable (ECV). The Global Terrestrial Network for Glaciers (GTN-G) was established in 1999 with the task of coordinating measurements and to ensure the continuous development and adaptation of the international strategies to the long-term needs of users in science and policy. The basic monitoring principles must be relevant, feasible, comprehensive and understandable to a wider scientific community as well as to policy makers and the general public. Data access has to be free and unrestricted, the quality of the standardized and calibrated data must be high and a combination of detailed process studies at selected field sites with global coverage by satellite remote sensing is envisaged. Recently a GTN-G Steering Committee was established to guide and advise the operational bodies responsible for the international glacier monitoring, which are the World Glacier Monitoring Service (WGMS), the US National Snow and Ice Data Center (NSIDC), and the Global Land Ice Measurements from Space (GLIMS) initiative. Several online databases containing a wealth of diverse data types having different levels of detail and global coverage provide fast access to continuously updated information on glacier fluctuation and inventory data. For world-wide inventories, data are now available through (a) the World Glacier Inventory containing tabular information of about 130,000 glaciers covering an area of around 240,000 km2, (b) the GLIMS-database containing digital outlines of around 118,000 glaciers with different time stamps and (c) the Randolph Glacier Inventory (RGI), a new and globally complete digital dataset of outlines from about 180,000 glaciers with some meta-information, which has been used for many applications relating to the IPCC AR5 report. Concerning glacier changes, a database (Fluctuations of Glaciers) exists containing information about mass balance, front variations including past reconstructed time series, geodetic changes and special events. Annual mass balance reporting contains information for about 125 glaciers with a subset of 37 glaciers with continuous observational series since 1980 or earlier. Front variation observations of around 1800 glaciers are available from most of the mountain ranges world-wide. This database was recently updated with 26 glaciers having an unprecedented dataset of length changes from from reconstructions of well-dated historical evidence going back as far as the 16th century. Geodetic observations of about 430 glaciers are available. The database is completed by a dataset containing information on special events including glacier surges, glacier lake outbursts, ice avalanches, eruptions of ice-clad volcanoes, etc. related to about 200 glaciers. A special database of glacier photographs contains 13,000 pictures from around 500 glaciers, some of them dating back to the 19th century. A key challenge is to combine and extend the traditional observations with fast evolving datasets from new technologies.

Hoelzle, Martin; Armstrong, Richard; Fetterer, Florence; Grtner-Roer, Isabelle; Haeberli, Wilfried; Kb, Andreas; Kargel, Jeff; Nussbaumer, Samuel; Paul, Frank; Raup, Bruce; Zemp, Michael

2014-05-01

123

Subglacial drainage processes at a High Arctic polythermal valley glacier  

E-print Network

, polythermal valley glacier situated in eastern Ellesmere Island, Nunavut, Canada (Fig. 1). The specific Glacier, Ellesmere Island, Canada, were designed to investigate the character of the subglacial drainage

124

Integration of glacier databases within the Global Terrestrial Network for Glaciers (GTN-G)  

NASA Astrophysics Data System (ADS)

Changes in glaciers and ice caps provide some of the clearest evidence of climate change and have impacts on global sea level fluctuations, regional hydrological cycles and local natural hazard situations. Internationally coordinated collection and distribution of standardized information about glaciers and ice caps was initiated in 1894 and is today coordinated within the Global Terrestrial Network for Glaciers (GTN-G). A recently established GTN-G Steering Committee coordinates, supports and advices the operational bodies responsible for the international glacier monitoring, which are the World Glacier Monitoring Service (WGMS), the US National Snow and Ice Data Center (NSIDC) and the Global Land Ice Measurements from Space (GLIMS) initiative. In this presentation, we provide an overview of (i) the integration of the various operational databases, (ii) the development of a one-stop web-interface to these databases, and (iii) the available datasets. By joint efforts consistency and interoperability of the different glacier databases is elaborated. Thereby, the lack of a complete worldwide, detailed glacier inventory as well as different historical developments and methodological contexts of the datasets are major challenges for linking individual glaciers throughout the databases. A map-based web-interface, implemented based on OpenLayer 2.0 and Web Map/Feature Services, is elaborated to spatially link the available data and to provide data users a fast overview of all available data. With this new online service, GTN-G provides fast access to information on glacier inventory data from 100,000 glaciers mainly based on aerial photographs and from 80,000 glaciers mainly based on satellite images, length change series from 1,800 glaciers, mass balance series from 230 glaciers, special events (e.g., hazards, surges, calving instabilities) from 130 glaciers, as well as 10,000 photographs from some 470 glaciers.

Zemp, M.; Raup, B. H.; Armstrong, R.; Ballagh, L.; Grtner-Roer, I.; Haeberli, W.; Hoelzle, M.; Kb, A.; Kargel, J.; Paul, F.

2009-04-01

125

Ice thickness, ablation, and other glaciological measurements on upper Fremont Glacier, Wyoming  

USGS Publications Warehouse

Glaciological investigations of the Upper Fremont Glacier in the Wind River Range of Wyoming were conducted during 1990-1991. The glaciological data will provide baseline information for monitoring future changes to the glacier and support ongoing research utilizing glacial-ice-core composition to reconstruct paleoenvironmental records. Ice thickness, determined by radio-echo sounding, ranged from 60 to 172 m in the upper half of the glacier. Radio-echo sounding of ice thickness at one point was confirmed by drilling 159.7 m to bedrock. Annual ablation (including snow, firn, and ice) measured for the 1990-1991 period averaged about 0.93 m/a. Surface ice velocity and direction were monitored from July 1990 to August 1991. Ice velocity decreased in a downslope direction. The largest measured velocity was about 3.1 m/a and the smallest was 0.8 m/a. -from Authors

Naftz, D.L.; Smith, M.E.

1993-01-01

126

Energy Balance and Hydrological Modelling of Zongo Glacier, Bolivia, Using ERA-40 Reanalysis Data  

NASA Astrophysics Data System (ADS)

In the Andes several regions profit significantly from glacial melt water for drink water supply and electricity production. During the dry season, glacier melt is significant source of water in the semi-arid region of La Paz, Bolivia. The Andean glaciers are retreating and water resources after reaching a culmination, will decrease. This implicates serious environmental and socio-economical consequences. For an effective attenuation, it is crucial to furnish quantitative predictions of the glacier mass loss and its effects on the water resources in these regions. A distributed energy balance model has been developed to model mass balance and melt induced discharge of tropical glaciers. We want to predict the changes in glacier melt discharge in response to future climate change for the region of La Paz, Bolivia and later regionalize the model to a larger area. The model operates on daily steps, has a 20 m grid resolution, and is forced by daily data of air temperature, humidity, wind speed, global radiation and precipitation. As a test basin, we calibrate the model at Glaciar Zongo, Bolivia, 1615'S , 6810'W which is monitored by the French Institute for Research for the Development (IRD) . Zongo Glacier is a 1,8 km2 large and the catchment is 63% glacierized. Mass balance, weather station and discharge data are available on daily basis from 1991 onward. The measurements have gaps and only two years (1994-95 and 1999-00) with continuous data are available. In order to allow for multi-year simulations we force the model by daily ERA-40 reanalysis data from the European Center for Weather Forecast (ECMWF). To downscale the data we compare the daily data 1991-2002 to the observations at the glacier. Results indicate a fair agreement for air temperature, but a rather poor correlation between the ERA-40 data and the observations for wind speed, global radiation and precipitation. The correlation is improved using monthly values. So far, test runs of the model using downscaled ERA-40 data for the Zongo Glacier show good agreement for the mass balances (r2=0.88) and relatively good estimate of the monthly melt discharge (r2=0.74). The transition between the wet and dry season is well captured by the model

Duguay, M.; Hock, R.; Sicart, J.; Coudrain, A.

2008-12-01

127

Glaciers. Attribution of global glacier mass loss to anthropogenic and natural causes.  

PubMed

The ongoing global glacier retreat is affecting human societies by causing sea-level rise, changing seasonal water availability, and increasing geohazards. Melting glaciers are an icon of anthropogenic climate change. However, glacier response times are typically decades or longer, which implies that the present-day glacier retreat is a mixed response to past and current natural climate variability and current anthropogenic forcing. Here we show that only 25 35% of the global glacier mass loss during the period from 1851 to 2010 is attributable to anthropogenic causes. Nevertheless, the anthropogenic signal is detectable with high confidence in glacier mass balance observations during 1991 to 2010, and the anthropogenic fraction of global glacier mass loss during that period has increased to 69 24%. PMID:25123485

Marzeion, Ben; Cogley, J Graham; Richter, Kristin; Parkes, David

2014-08-22

128

Himalayan glacier retreat delayed by debris cover  

Microsoft Academic Search

Variable retreat rates and paucity of mass-balance data complicate a coherent picture of the current state and future fate of Himalayan glaciers. We report frontal changes and remotely-sensed surface velocities from >250 glaciers in the greater Himalayan realm (Hindu Kush, Karakoram, Himalaya, West Kunlun Shan) between 2000 and 2008 that provide evidence for widespread meltdown, which is obscured by debris

D. Scherler; B. Bookhagen; M. R. Strecker

2010-01-01

129

Recent wastage of Bering Glacier, Alaska  

NASA Astrophysics Data System (ADS)

The glaciers on the south coast of Alaska are melting rapidly with local, regional and global impacts. A five year record of the annual wastage of Bering Glacier, from 2004 to 2008, shows that as much as 30 km3 of glacial melt water flows into the Gulf of Alaska. These estimates were obtained by combining in situ melt measurements carried out from near sea level to 1400 m, glacier coverage derived from Landsat-7 and ASTER observations, and a digital elevation model derived from ASTER stereo observations. The total freshwater flux from the Bering Glacier System into the Gulf of Alaska is as much as 5% of the total estimated annual flux from the coastal region of Alaska. For this period, Bering glacier has retreated at an average rate of 0.5 km per year, as the ice in the terminus region thins and calving and disarticulation increases. However, terminus retreat only accounts for 5 to 10% of the total wastage. The wastage of Bering glacier showed a strong correlation with the cumulative positive degree days measured both on the glacier and at the Yakutat Airport 220 km to the east. This correlation allows these results to be used to simulate anticipated impacts of climate warming on the glaciers of this region. For example, the summer of 2004 was one of the warmest on record, equivalent to a 2 C temperature increase in the daily average temperature at Yakutat.

Josberger, E. G.; Shuchman, R. A.

2009-12-01

130

Muir Glacier and Muir Inlet 2003  

USGS Multimedia Gallery

This photo was taken in September 2003; in the 23 years between photographs, Muir Glacier has retreated more than a mile and ceased to have a tidewater terminus. Since 1980, Muir Glacier has thinned by more than 600 ft, permitting a view of a mountain with a summit elevation of greater than 4000 ft,...

131

Using Metaphorical Models for Describing Glaciers  

ERIC Educational Resources Information Center

To date, there has only been little conceptual change research regarding conceptions about glaciers. This study used the theoretical background of embodied cognition to reconstruct different metaphorical concepts with respect to the structure of a glacier. Applying the Model of Educational Reconstruction, the conceptions of students and scientists

Felzmann, Dirk

2014-01-01

132

GLACIER PEAK ROADLESS AREA, WASHINGTON.  

USGS Publications Warehouse

A mineral survey outlined areas of mineral-resource potential in the Glacier Peak Roadless Area, Washington. Substantiated resource potential for base and precious metals has been identified in four mining districts included in whole or in part within the boundary of the roadless area. Several million tons of demonstrated base- and precious-metal resources occur in numerous mines in these districts. Probable resource potential for precious metals exists along a belt of fractured and locally mineralized rock extending northeast from Monte Cristo to the northeast edge of the roadless area.

Church, S.E.; Johnson, F.L.

1984-01-01

133

Radio-echo sounding of Caucasus glaciers  

NASA Astrophysics Data System (ADS)

Accurate glacier volume and ice-thickness estimations are highly important for many glaciological applications. Recent glacier reduction is affecting local river discharge and contributes to the global sea level rise. However, direct measurements of ice thickness are very sparse due to its high cost and laboriousness. One of the glacierized mountain regions with a lack of direct ice-thickness measurements is Caucasus. So far data for several seismic and GPR profiles have been reported for only 3 glaciers from more than 1.7 thousands located in Caucasus. In 2010-2012 a number of ground base and airborne radio-echo sounding surveys have been accomplished in Caucasus Mountains using 20 MHz monopulse radar VIRL-6. Special aerial version of this ground penetrating radar was designed for helicopter-born measurements. The radar has a relatively long (10 m) receiving and transmitting antennas, which together with receiving, recording and transmitting devices can be mounted on a special girder, being suspended from a helicopter. VIRL-6 radar is light weight and can be quickly transformed into ground version. Equipment has been used on 16 glaciers including biggest glacier in Caucasus - Bezengi (36 km2) most of which have a highly crevassed surfaces and heterogeneous internal structure. Independent data were obtained also for two glaciers using ground version of the same VIRL-6 radar. In total more than 120 km of radar profiles were obtained. Results showed good agreement between ground and aerial measurements. Ice-thickness values exceeded 420 m for some of the Central Caucasus glaciers. Successful use of VIRL-6 radar in Caucasus opens up the possibility of using such equipment on different types of glaciers in polar and mountain regions, including temperate, polythermal and surging glaciers.

Lavrentiev, Ivan; Kutuzov, Stanislav; Vasilenko, Evgeny; Macheret, Yuri

2013-04-01

134

A field and glacier modelling based approach to determine the timing and extent of glaciation in southern Africa  

NASA Astrophysics Data System (ADS)

Moraines identified at high-altitude sites in southern Africa and dated to the last glacial maximum (LGM) indicate that the climate in this region was cold enough to support glaciers. Small glaciers are very sensitive to changes in temperature and precipitation and the identification of LGM moraines in southern Africa has important palaeoclimatic implications concerning the magnitude of temperature change and the seasonality of precipitation during the last glacial cycle. This paper presents a refined time-frame for likely glaciations based on surface exposure dating using Cl-36 at sites in Lesotho and reports results of a 2D glacier energy balance and ice flow modelling approach (Plummer and Phillips, 2003) to evaluate the most likely climatic scenarios associated with mapped moraine limits. Samples for surface exposure dating were collected from glacially eroded bedrock at several locations and yield ages within the timescale of the LGM. Scatter in the ages may be due to insufficient erosion of the bedrock surface due to the small and relatively thin nature of the glaciers. To determine the most likely climatic conditions that may have caused the glaciers to reach their mapped extent, we use a glacier-climate model, driven by data from local weather stations and a 30m (ASTER) DEM (sub-sampled to 10m) representation of the topographic surface. The model is forced using modern climate data for primary climatic controls (temperature and precipitation) and for secondary climatic parameters (relative humidity, cloudiness, wind speed). Various sensitivity tests were run by dropping temperature by small increments and by varying the amount of precipitation and its seasonality relative to present-day values. Results suggest that glaciers could have existed in the Lesotho highlands with a temperature depression of ~5-6 C and that the glaciers were highly sensitive to small changes in temperature. The additional accumulation of mass through wind redistribution appears to have been important at all but a few sites, suggesting that this must be taken into account when trying to determine a regional climate signal from small glaciers. Our dating and glacier-climate model simulations reinforce the idea that small glaciers existed in the Lesotho Highlands during the LGM, under climatic scenarios that are consistent with other proxy records. Plummer, M.A. and Phillips, F.M. (2003) 2-D numerical model of snow/ice energy balance and ice flow for paleoclimatic interpretation of glacial geomorphic features. Quaternary Science Reviews, 22, 1389-1406.

Mills, Stephanie C.; Rowan, Ann V.; Barrow, Timothy T.; Plummer, Mitchell A.; Smith, Michael; Grab, Stefan W.; Carr, Simon J.; Fifield, L. Keith

2014-05-01

135

Mapping Glacier Data and Photographs via GeoServer and Virtual Globes  

Microsoft Academic Search

Two extensively used glacier data sets include the World Glacier Inventory and the Glacier Photograph Collection. Both data sets are hosted at the National Snow and Ice Data Center in Boulder, Colorado. The World Glacier Inventory encompasses over 100,000 records of glacier data and the Glacier Photograph Collection houses approximately 9,000 digitized photographs. The online Glacier Photograph Collection has doubled

L. M. Ballagh; I. Wang; A. Wallace

2008-01-01

136

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

137

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

138

Glacier Change in the Rwenzori Mountains, East Africa  

Microsoft Academic Search

In East Africa glaciers currently exist on Mt. Kilimanjaro and Mt. Kenya, and in the Rwenzori Mountains. While the Mt. Kilimanjaro and Mt. Kenya glaciers have been the subject of many recent studies, the glaciers in the Rwenzori Range are less thoroughly studied. This study reexamines the satellite record of retreat of these glaciers, as well as the climatic factors

J. L. Kincaid; A. G. Klein

2007-01-01

139

A conceptual model of cyclical glacier flow in overdeepenings  

NASA Astrophysics Data System (ADS)

A nearly four-decade, satellite-based velocity survey of the largest glaciers in the Alaska Range, Chugach Mountains, and the Wrangell Mountains of southern Alaska, spanning the early- to mid-1970s through the 2000s, reveals nine pulsing glaciers: Capps, Copper, Eldridge, Kahiltna, Matanuska, Nabesna, Nizina, Ruth, and Sanford glaciers. The pulses increase velocity by up to 2449% (Capps Glacier) or as little as 77% (Nabesna Glacier), with velocity increases for the other glaciers in the range of 100-250%. The pulses may last from between six years (Copper Glacier) to 12 years (Nizina Glacier) and consist of a multi-year acceleration phase followed by a multi-year deceleration phase during which significant portions of each glacier move en masse. The segments of each glacier affected by the pulses may be anywhere from 14 km (Sanford Glacier) to 36 km (Nabesna Glacier) in length and occur where the glaciers are either laterally constricted or joined by a major tributary, and the surface slopes at these locations are very shallow, 1-2, suggesting the pulses occur where the glaciers are overdeepened. A conceptual model to explain the cyclical behavior of these pulsing glaciers is presented that incorporates the effects of glaciohydraulic supercooling, glacier dynamics, surface ablation, and subglacial sediment erosion, deposition, and deformation in overdeepenings.

Turrin, J. B.; Forster, R. R.

2014-08-01

140

Step-wise changes in glacier flow speed coincide with calving and glacial earthquakes at Helheim Glacier, Greenland  

Microsoft Academic Search

Geodetic observations show several large, sudden increases in flow speed at Helheim Glacier, one of Greenland's largest outlet glaciers, during summer, 2007. These step-like accelerations, detected along the length of the glacier, coincide with teleseismically detected glacial earthquakes and major iceberg calving events. No coseismic offset in the position of the glacier surface is observed; instead, modest tsunamis associated with

M. Nettles; T. B. Larsen; P. Elsegui; G. S. Hamilton; L. A. Stearns; A. P. Ahlstrm; J. L. Davis; M. L. Andersen; J. de Juan; S. A. Khan; L. Stenseng; G. Ekstrm; R. Forsberg

2008-01-01

141

Sensitivity of glaciers and small ice caps to greenhouse warming  

Microsoft Academic Search

Recent field programs on glaciers have supplied information that makes simulation of glacier mass balance with meteorological models meaningful. An estimate of world-wide glacier sensitivity based on a modeling study of 12 selected glaciers situated in widely differing climatic regimes shows that for a uniform 1 K warming the area-weighted glacier mass balance will decrease by 0.40 meter per year.

J. Oerlemans; J. P. F. Fortuin

1992-01-01

142

Monitoring of Grandes Jorasses hanging glacier (Aosta Valley, Italy): improving monitoring techniques for glaciers instability  

NASA Astrophysics Data System (ADS)

Grandes Jorasses serac is an unbalanced hanging glacier located on the south side of Mont Blanc Massif (Aosta Valley - Italy). It stands above Ferret Valley, a famous and most frequented touristic site both in winter and summer. Historical data and morphological evidences show that the glacier is subject to recurrent icefalls which can be dangerous especially in winter, as they can trigger catastrophic combined snow and ice avalanches. Serac dynamic was monitored in 1997-98 by prof. M Funk (ETH Zurich) by means of temperature and topographic measurement. These allowed to forecast the breakdown within a 2 days time. Thanks to a monitoring program, a new instability could be recognized in autumn 2008: a crevasse opening in the lower part of the hanging glacier. A new monitoring system was installed recently, consisting of stakes with prisms on serac surface and an automatic total station (theodolite plus distantiometer) sited on the valley floor. Monitoring is based on an empirically based power law (developed by ETH) that describes the increasing displacement rate before collapse. This monitoring system requires to measure displacement rate of the serac continuously. Although the topographic system is so far the state-of-the.art method, it implies some troubles: (i) the difficulty in placing stakes on the steep and dangerous glacier surface; (ii) potential instability of stakes themselves due to snow pressure in winter and surface ice melting in summer; (iii) impossibility to carry out measurement in case of cloudy or stormy weather, which is rather a frequent situation on Grandes Jorasses peak. Moreover, hazard and risk management require some more informations, such as the instable ice mass volume. New technologies have been applied, and are still under test, to achieve a more reliable monitoring system and a better understanding of the serac dynamics. Close-range photogrammetry techniques have been used, allowing to process helicopter-taken images and obtain quantitative data about the serac volume and crevasses widening. A low-cost GPS station has been installed in the upper part of the serac, in order to obtain long-term, continuous displacement data even in bad weather conditions. A seismograph has been installed to measure the seismic activity of the serac. The latter, as observed by ETH, significantly evolves before the seracfall; thus, the record of the seismic activity can be used to forecast the break-off. Finally, a ground-based SAR system has been tested to infer seracs displacement. Possible avalanches scenarios consequent to an icefall have been calculated by numerical simulation by the SLF Institute of Davos. In-situ measurement techniques have to be designed to resist often in the difficult environmental conditions (low temperature, frost, wind), dealing, e.g. with power supply and data transmission, and purpose-made technical solutions are often necessary. The development of these techniques will contribute to an improved understanding of the seracs dynamics and provide a more reliable monitoring tool.

Vagliasindi, Marco; Funk, Martin; Faillettaz, Jerome; Dalban, Pierre; Lucianaz, Claudio; Diotri, Fabrizio; Motta, Elena; Margreth, Stephan

2010-05-01

143

Central Himalayan Glaciers and Climate Change- Pinder Glacier- A preliminary study  

NASA Astrophysics Data System (ADS)

Glaciers in the Indian Himalayan Region (IHR) are the prime lifeline of Indian Subcontinent. There are about nine thousand glaciers of different size in this region. It is located within the latitudes 270N to 360N and longitude 720E to 960E. The second largest glacier, outside the polar and sub polar regions, Siachen glacier of length 74 km, is located in IHR. Many rivers in this continent originated from these glaciers. Study on the fluctuations especially of the snow cover and related parameters are important for the proper management of these rivers. Annual balance, fluctuations of glaciers, hydrological behaviour and the assessment of the winter snow pack are also critical for the proper flow and control of Himalayan Rivers. There are many hydroelectric and irrigation facilities in these snow fed rivers. Glacial melt is important as far as the river flow is concerned. Researchers had observed that the glacial mass balance has been found to show an inverse relationship with the monsoon. Glacial hydrometry and glacial melt are important aspects as far the studies of glaciers in this region. Himalayan glaciers are also important for ecosystem stability. In this perspective attempts had been made to examine the various environmental parameters of Pindari glacier and the upper reaches of the Pindari river. Pindari glacier is located in the Central Himalayan region. It is of length 8 Km. A few records available with Geological Survey of India for a period of hundred years reveals that Pindari glacial have an annual retreat of 8-10 M. Pindrai glacier had retreated about 425 M with in a period of fifty seven years. Pindari river originates from the buffer zone of Nanda Devi Biosphere Reserve (NDBR) and is located in the lower regime of Pindari glacier. It is one of the prominent tributaries of Alaknanda. Tributaries of Pindari river are from Maktoli glacier, Kafani glacier and Sunderdhunga glacier. The changes in the Pindiari catchment area had been examined from the year 1990. Remote Sensing data of different years were used to analyze the changes in aerial extent of the pindari glacier. Pindari landscap is formed by the combined geomorphological process of fluvial and glacial. These processes are also maintaining the ecosystem balance of the catchment area. Snow covers area of this higher landscapet had been reduced considerably. The timberline of this region is shifting upper side of the glaciers, whereas the equilibrium line is also retreating. The spatial invasion in timber line and the retreat of the equilibrium line will further establish the negative mass balance of this glacier. However, the climatic variation may exacerbate the ecosystem balance of the region. All the reports on the glaciers in IHR regions review a negative mass balance and annual retreat up the glaciers. The observation records of these glaciers in IHR are about a period of hundred years this is quite in sufficient it establishes the relation between climate change and the glaciers retreat. However it is a known fact that the impact of rise in temperature due to anthropogenic effect may overstretch the rate the natural process of glacier retreat. The present study also discusses the unique phenomena of glacier melt due to climatic variations and its catastrophe.

Pillai, J.; Patel, L. K.

2011-12-01

144

Interaction between glacier and glacial lake in the Bhutan, Himalaya  

NASA Astrophysics Data System (ADS)

Recession of mountain glaciers in the Himalayas has been reported in the context of global warming. Associated with the glacier retreat, supraglacial lakes have been formed on the termini of debris-covered glaciers. Although it has been said that lake-terminating glaciers flow faster than land-terminating glaciers, observational evidence was scarce. We observationally investigated the influence of the presence/absence of glacial lakes on changes in surface elevation through glacier dynamics in two debris-covered glaciers, Thorthormi Glacier (land-terminating) and Lugge Glacier (lake-terminating), in the Lunana region, the Bhutan Himalaya. We surveyed the surface elevation of debris-covered areas of the two glaciers in 2004 and 2011 by a differential GPS. Change in surface elevation of the lake-terminating Lugge Glacier was much more negative than that of the land-terminating Thorthormi Glacier. Considering almost flat slope and location at lower elevation, however, larger ice thinning rate of the Thorthormi Glacier should have been expected than the Lugge Glacier. We measured surface flow speed of the two glaciers during 2009-2010 by multitemporal orthorectified The Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) images of ALOS. Surface flow speed of the Thorthormi Glacier was faster in the upper reaches and reduced toward the downstream. In contrast, the flow speed at the Lugge Glacier measured in the same periods was greatest at the lower most part. Observed spatial distribution of surface flow speed at both glaciers are evaluated by a two-dimensional numerical flow model. The model shows that contribution of basal sliding to surface flow velocity is large in the lower part of both glaciers. Particularly in the Thorthormi Glacier, approximately 100% of surface flow velocity attribute to basal sliding. Calculated emergence velocity at the Thorthormi Glacier is larger than that at the Lugge Glacier. This result suggests that decreasing in flow velocity towards the terminus in the Thorthormi Glacier causes compressive flow and thus counterbalances surface melting, resulting in inhibition of the surface lowering. In contrast, the extensional flow of the Lugge Glacier accelerated the surface lowering. In this study we show the observational evidences, in which the glacier lake formation makes contrast the thinning rates of glaciers in the Bhutan Himalaya. If the supraglacial lake on Thorthormi Glacier expands, the surface lowering will be accelerated in the future.

Tsutaki, S.; Fujita, K.; Yamaguchi, S.; Sakai, A.; Nuimura, T.; Sugiyama, S.; Komori, J.; Takenaka, S.; Tshering, P.

2012-12-01

145

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.

Manley, William

146

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

NASA Astrophysics Data System (ADS)

Runoff from the Canadian Rocky Mountains into the Upper Columbia and Kootenay basins is strongly dominated by winter snow accumulation and spring melt, and it has been suggested that future reductions in snowpack will create increased competition for water between spring and early fall (Hamlet & Lettenmaier, 1999). Although the glacierised area is substantial for affecting summer flows in these basins, there are no measurements or quantified estimates of glacier runoff contribution. In an effort to provide an estimate of glacier runoff for the region, we measured ablation over 5 years, set up weather stations and temperature sensors in Summers 2009 and 2010 and developed a melt model for Shackleton Glacier (42.5 km2), the largest outlet of the Clemenceau Icefield Group (271 km2), which is the major local ice mass feeding into the Upper Columbia basin. Two HOBO weather stations (WS) were installed on the glacier for two weeks in Summer 2010, one near the left lateral moraine on very dirty ice, and one mid-glacier on relatively clean ice. Instrumentation included pyranometers (solar radiation and albedo), and temperature, wind speed and direction, relative humidity and barometric pressure sensors. A weather station off ice provided additional temperature and precipitation data. Other data included daily ablation stake measurements, surface roughness measurements, temperature data from Tidbit loggers on and off ice, and daily manual weather observations. Yearly ablation stake measurements and summer weather observations have been made by our team since 2005. A BC River Forecast Centre automatic snow pillow station provides additional temperature and precipitation data. Using these meteorological and ablation data for parameterisation and optimisation, a distributed GIS melt model was constructed from a simple energy balance model. The model is driven by hourly direct and diffuse radiation and DEM hillshading, an albedo parameterisation based on four ice/snow zones identified from a satellite image and field measurements, constant daily values of longwave radiation as a function of percent cloud cover, and sensible heat input as a function of air temperature, katabatic wind, surface roughness and elevation. Latent heat was considered negligible. Novel aspects of the melt model include a valley temperature threshold for katabatic wind (using on and off ice temperatures and katabatic wind speed) and slope corrected area melt and radiation calculations. In an attempt to quantify energy balance effects of tributary-trunk detachment due to glacier recession related glacier fragmentation, special attention was paid to the potential influence from lateral moraines and valley walls and very dirty ice on the ablation in ice marginal regions. Observations suggest that, when katabatic wind diminishes, heat advection from an even moderately warmer lateral moraine can raise nearby glacier temperature substantially. This suggests that a combination of katabatic wind fields and proximity to lateral moraines/rock walls may be important in calculations of sensible heat contribution to surface melt in recently fragmented glacier systems.

Mueller, M.; Jiskoot, H.

2010-12-01

147

Modeled Climate-Induced Glacier Change in Glacier National Park, 1850--2100  

NSDL National Science Digital Library

This peer-reviewed article from BioScience journal is about the glacier change in Glacier National park. The glaciers in the Blackfoot--Jackson Glacier Basin of Glacier National Park, Montana, decreased in area from 21.6 square kilometers (km2) in 1850 to 7.4 km2 in 1979. Over this same period global temperatures increased by 0.45 degrees C (+/- 0.15 degrees C). We analyzed the climatic causes and ecological consequences of glacier retreat by creating spatially explicit models of the creation and ablation of glaciers and of the response of vegetation to climate change. We determined the melt rate and spatial distribution of glaciers under two possible future climate scenarios, one based on carbon dioxide--induced global warming and the other on a linear temperature extrapolation. Under the former scenario, all glaciers in the basin will disappear by the year 2030, despite predicted increases in precipitation; under the latter, melting is slower. Using a second model, we analyzed vegetation responses to variations in soil moisture and increasing temperature in a complex alpine landscape and predicted where plant communities are likely to be located as conditions change.

MYRNA H. P. HALL and DANIEL B. FAGRE (;)

2002-02-01

148

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

NASA Astrophysics Data System (ADS)

An experimental site was setup in 2005 on the ablation area of La Mare Glacier, at 2990 m a.s.l., to study the energy and mass balance exchanges between the glacier surface and the atmosphere and to investigate the climatic sensitivity of this particular glacier. An Automatic Weather Station was operated, in the framework of a monitoring network which has been implemented in the Upper Val de La Mare experimental watershed (Trentino, Italy). This basin was selected for a study of climate change effects on cryosphere and hydrology at high-altitude catchments. The 36.2 km2 wide basin has an average altitude of 2906 m a.s.l. and at present the 25% of its surface is glacierized; the annual runoff regime is dominated by snow and ice melt. Direct mass balance measurements have been performed since 1967 on Careser glacier (2.83 km2) and since 2003 on La Mare glacier (3.97 km2). The AWS is mounted on a tripod which stands freely on the glacier surface and is solar-powered. The variables measured are: air temperature and relative humidity, wind speed and direction, shortwave and longwave incoming and outgoing radiation, precipitation and surface height. All the data are sampled at five-minute intervals as average values, with the exception of surface height which is sampled at hourly intervals, as instantaneous values. The collected data were used to calculate the point energy and mass balance and to compare the results with similar investigations carried out on glaciers and available in literature. In particular, our attention has been focussed on some processes which regulate the response to climate changes. The relative importance of the energy balance components was examined and a clear predominance of shortwave radiation inputs was found to exist during melt conditions. Given the relevance of the shortwave net balance, the ice albedo temporal variability (values ranging from 0.1 to 0.5) has been investigated and correlated with meteorological variables. Furthermore, a distinct diurnal cycle of cloud cover was found to control the actual radiation received by the surface, with a minimum coverage at morning and a maximum at late afternoon, due to thermal convection. In addition, the energy available for melt is affected by the glacier cooling effect, which produces a persistent katabatic wind and lead to a reduced climatic sensitivity with respect to the "free atmosphere". The magnitude of the cooling effect has proved to be comparable with the findings of similar studies conducted in other European glaciers. Finally, the data of the first winter highlighted a very low accumulation on the AWS site, due to strong wind erosion of freshly fallen dry and cold snow. Accumulation became significant only in spring, with the deposition of snow in higher temperature conditions and absence of post-event strong northerly winds.

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

2009-04-01

149

Surface winds over West Antarctica  

NASA Technical Reports Server (NTRS)

Five winter months (April-August 1988) of thermal infrared satellite images were examined to investigate the occurrence of dark (warm) signatures across the Ross Ice Shelf in the Antarctic continent. These features are inferred to be generated by katabatic winds that descend from southern Marie Byrd Land and then blow horizontally across the ice shelf. Significant mass is added to this airstream by katabatic winds blowing from the major glaciers that flow through the Transantarctic Mountains from East Antarctica. These negatively buoyant katabatic winds can reach the northwestern edge of the shelf - a horizontal propagation distance of up to 1,000 km - 14 percent of the time. Where the airstream crosses from the ice shelf to the ice-covered Ross Sea, a prominent coastal polynya is formed. Because the downslope buoyancy force is near zero over the Ross Ice Shelf, the northwestward propagation of the katabatic air mass requires pressure gradient support. The study shows that the extended horizontal propagation of this atmospheric density current occurred in conjunction with the passage of synoptic cyclones over the southern Amundsen Sea. These cyclones can strengthen the pressure gradient in the interior of West Antarctica and make the pressure field favorable for northwestward movement of the katabatic winds from West Antarctica across the ice shelf in a geostrophic direction. The glacier winds from East Antarctica are further accelerated by the synoptic pressure gradient, usually undergo abrupt adjustment beyond the exit to the glacier valley, and merge into the mountain-parallel katabatic air mass.

Bromwich, David

1993-01-01

150

Common Misconceptions about Icebergs and Glaciers  

NSDL National Science Digital Library

This article describes some common misconceptions that elementary students may have about icebergs and glaciers (including density and buoyancy). It also includes suggestions for formative assessment and teaching for conceptual change.

Fries-Gaither, Jessica

151

Liss M. Andreassen Glacier variations in  

E-print Network

by The University Foundation for Student Life (SiO) #12;"Jeg hilser dig land i det luftige blå, forklaret av ....................................................................................................................... 15 1.1 Motivation........................................................................................... 21 2.3 Glacier survey using remote sensing methods

Andreassen, Liss Marie

152

What Are the Physical Effects of Glaciers?  

NSDL National Science Digital Library

This text explains how glaciers scour and grind the Earth's surface, and about the sorts of deposits they leave behind. Emphasis is on glaciation in the mountains and valleys of Vermont. Links to related topics are included.

153

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

154

Towards a complete World Glacier Inventory  

NASA Astrophysics Data System (ADS)

The need for an inventory of the world's glaciers evolved during the International Hydrological Decade (1965-74). As a result, guidelines were established in the mid 1970s to compile a worldwide detailed inventory of existing perennial snow and ice masses. Following these international guidelines, several countries started compiling national glacier inventories based primarily on aerial photographs and maps. In the 1980s, the World Glacier Inventory (WGI) database was launched together with a status report about global and regional glacierised surface areas for the second half of the 20th century. These estimates were based on the detailed inventory data together with preliminary estimates of the remaining glacierised regions derived from early satellite imagery. In the late 1990s, the Global Land Ice Measurements from Space (GLIMS) database was initiated to continue the inventory task with space-borne sensors. In the WGI, glaciers are represented by geographical point coordinates. The GLIMS database includes digital outlines. Both include exact time stamps and tabular information on glacier classifications, length, area, orientation, and altitude range. Both are regularly updated with newly available data: the WGI stores point information for the second half of the 20th century whereas the GLIMS includes digital outlines for the 21st century. Since these detailed glacier inventories are not (yet) globally complete, there have been several efforts towards preliminary estimates of the overall global glacier coverage. A first, well elaborated one was included in the original status report of the WGI, published in 1989, and was refined in 2005 with information from other sources by Dyurgerov and Meier. Other studies used the detailed WGI, or an extended format by Cogley, for regional or global up-scaling of glacier extents. In 2003, Cogley published a global map of percentage glacier coverage per 1x1 grid box (GGHydro) that is widely used for modeling at global scale. A first globally and almost complete map with (generalized) digital outlines of all ice covered regions (incl. Greenland but excluding Antarctica) was derived from ESRI's Digital Chart of the World (DCW) and other sources by Raup and colleagues in 2000. Most recently, Arendt and colleagues produced the Randolph dataset which combines available outlines from the GLIMS, DCW, and WGI datasets as well as from many other (often unpublished) sources by using the highest quality version in each region. However, while having the advantage of being almost complete, these global estimates lack time stamps and attributes for individual glaciers. The present work provides a brief review of the various efforts, its methodological differences, and findings towards the completion of a World Glacier Inventory.

Zemp, Michael

2013-04-01

155

Glacier Inventory: A Case in Semiarid Chile  

Microsoft Academic Search

\\u000a Glaciers are the most important water reservoirs found in the Andes. While the scientific community has conducted more extensive\\u000a glaciological studies in southern Chile, it is only recently that attention has been focused on northern Chile. In the Chilean\\u000a Norte Chico region, where glaciation is restricted to the highest summits, the sparse glacier network provides the majority\\u000a of water to

Jorge Marn; Jos Araos

156

Impacts of Change in Glacier Ice  

NSDL National Science Digital Library

This is a five-activity module that explores the evidence for and impacts of melting glacial ice, with resources from major institutions and scientists who study glaciers -- primarily in Arctic areas. The suite of activities includes both glaciers and melting ice, as well as the impact of melt water downstream. Each activity follows the 5E model of Engagement, Exploration, Explanation, Elaboration, and Evaluation.

Grant, Alaska S.

157

The concept of glacier storage: a review  

Microsoft Academic Search

Glacier storage is a widely used term, applied to different processes and time-scales by different disciplines in hydrology and glaciology. We identify that storage occurs as ice, snow, and water associated with three time-scales. Long-term storage concerns storage of ice and firn as glaciers on time-scales of years to centuries and longer. This storage affects global sea level and long-term

Peter Jansson; Regine Hock; Thomas Schneider

2003-01-01

158

USGS Repeat Photography Project: Glacier National Park  

NSDL National Science Digital Library

This project, conducted by the United States Geological Survey (USGS), documents changes over time in the landscape of Glacier National Park, particularly the retreat of the park's glaciers. The project involves pairing historic photos from the park's archives with recent photos to illustrate how the landscape has changed. Users can view and download the photos in pairs with dates and a caption describing the scene and the changes that have taken place.

2010-11-22

159

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

160

Linking glacier annual mass balance and glacier albedo retrieved from MODIS data  

NASA Astrophysics Data System (ADS)

Spectroradiometer (MODIS) on board the TERRA and AQUA satellites, provide a means to monitor glacier surface albedo. In this study, different methods to retrieve broadband glacier surface albedo from MODIS data are compared. The effect of multiple reflections due to the rugged topography and of the anisotropic reflection of snow and ice are particularly investigated. The methods are tested on the Saint Sorlin Glacier (Grandes Rousses area, French Alps). The accuracy of the retrieved albedo is estimated using both field measurements, at two automatic weather stations located on the glacier, and albedo values derived from terrestrial photographs. For summers 2008 and 2009, the Root Mean Square Deviation (RMSD) between field measurements and the broadband albedo retrieved from MODIS data at 250m spatial resolution was found to be 0.052 or about 10% relative error. The RMSD estimated for the MOD10 daily albedo product is about three times higher. One decade (2000-2009) of MODIS data were then processed to create a time series of albedo maps of four glaciers in the French Alps including Saint Sorlin Glacier during the ablation season. The annual mass balance of each glacier was compared with the minimum albedo value (average over the whole glacier surface) observed with MODIS during the ablation season. A strong linear correlation exists between the two variables. Furthermore, the date when the average albedo of the whole glacier reaches a minimum closely corresponds to the period when the snowline is located at its highest elevation, thus when the snowline is a good indicator of the glacier equilibrium line. This indicates that this strong correlation results from the fact that the minimal average albedo values of the glacier contains a considerable information regarding the relative share of areal surfaces between the ablation zone (i.e. ice with generally low albedo values) and the accumulation zone (i.e. snow with a relatively high albedo). As a consequence, the monitoring of the glacier surface albedo using MODIS data can provide a useful means to evaluate the inter-annual variability of the glacier mass balance. Finally, the albedo in the ablation area of Saint Sorlin Glacier does not exhibit any decreasing trend over the study period, contrasting with the results obtained on Morteratsch Glacier in the Swiss Alps.

Dumont, M.; Gardelle, J.; Sirguey, P. J.; Guillot, A.; Dcaux, L.; Rabatel, A.; Six, D.; Arnaud, Y.

2012-12-01

161

Linking glacier annual mass balance and glacier albedo retrieved from MODIS data  

NASA Astrophysics Data System (ADS)

Albedo is one of the variables controlling the mass balance of temperate glaciers. Multispectral imagers, such as MODerate Imaging Spectroradiometer (MODIS) on board the TERRA and AQUA satellites, provide a means to monitor glacier surface albedo. In this study, different methods to retrieve broadband glacier surface albedo from MODIS data are compared. The effect of multiple reflections due to the rugged topography and of the anisotropic reflection of snow and ice are particularly investigated. The methods are tested on the Saint Sorlin Glacier (Grandes Rousses area, French Alps). The accuracy of the retrieved albedo is estimated using both field measurements, at two automatic weather stations located on the glacier, and albedo values derived from terrestrial photographs. For summers 2008 and 2009, the Root Mean Square Deviation (RMSD) between field measurements and the broadband albedo retrieved from MODIS data at 250 m spatial resolution was found to be 0.052 or about 10% relative error. The RMSD estimated for the MOD10 daily albedo product is about three times higher. One decade (2000-2009) of MODIS data were then processed to create a time series of albedo maps of Saint Sorlin Glacier during the ablation season. The annual mass balance of Saint Sorlin Glacier was compared with the minimum albedo value (average over the whole glacier surface) observed with MODIS during the ablation season. A strong linear correlation exists between the two variables. Furthermore, the date when the average albedo of the whole glacier reaches a minimum closely corresponds to the period when the snowline is located at its highest elevation, thus when the snowline is a good indicator of the glacier equilibrium line. This indicates that this strong correlation results from the fact that the minimal average albedo values of the glacier contains a considerable information regarding the relative share of areal surfaces between the ablation zone (i.e. ice with generally low albedo values) and the accumulation zone (i.e. snow with a relatively high albedo). As a consequence, the monitoring of the glacier surface albedo using MODIS data can provide a useful means to evaluate the inter-annual variability of the glacier mass balance. Finally, the albedo in the ablation area of Saint Sorlin Glacier does not exhibit any decreasing trend over the study period, contrasting with the results obtained on Morteratsch Glacier in the Swiss Alps.

Dumont, M.; Gardelle, J.; Sirguey, P.; Guillot, A.; Six, D.; Rabatel, A.; Arnaud, Y.

2012-07-01

162

Linking glacier annual mass balance and glacier albedo retrieved from MODIS data  

NASA Astrophysics Data System (ADS)

Albedo is one of the variables controlling the mass balance of temperate glaciers. Multispectral imagers, such as MODerate Imaging Spectroradiometer (MODIS) on board the TERRA and AQUA satellites, provide a means to monitor glacier surface albedo. In this study, different methods to retrieve broadband glacier surface albedo from MODIS data are compared. The effect of multiple reflections due to the rugged topography and of the anisotropic reflection of snow and ice are particularly investigated. The methods are tested on the Saint Sorlin Glacier (Grandes Rousses area, French Alps). The accuracy of the retrieved albedo is estimated using both field measurements, at two automatic weather stations located on the glacier, and albedo values derived from terrestrial photographs. For summers 2008 and 2009, the root mean square deviation (RMSD) between field measurements and the broadband albedo retrieved from MODIS data at 250 m spatial resolution was found to be 0.052 or about 10% relative error. The RMSD estimated for the MOD10 daily albedo product is about three times higher. One decade (2000-2009) of MODIS data were then processed to create a time series of albedo maps of Saint Sorlin Glacier during the ablation season. The annual mass balance of Saint Sorlin Glacier was compared with the minimum albedo value (average over the whole glacier surface) observed with MODIS during the ablation season. A strong linear correlation exists between the two variables. Furthermore, the date when the average albedo of the whole glacier reaches a minimum closely corresponds to the period when the snow line is located at its highest elevation, thus when the snow line is a good indicator of the glacier equilibrium line. This indicates that this strong correlation results from the fact that the minimal average albedo values of the glacier contains considerable information regarding the relative share of areal surfaces between the ablation zone (i.e. ice with generally low albedo values) and the accumulation zone (i.e. snow with a relatively high albedo). As a consequence, the monitoring of the glacier surface albedo using MODIS data can provide a useful means to evaluate the interannual variability of the glacier mass balance. Finally, the albedo in the ablation area of Saint Sorlin Glacier does not exhibit any decreasing trend over the study period, contrasting with the results obtained on Morteratsch Glacier in the Swiss Alps.

Dumont, M.; Gardelle, J.; Sirguey, P.; Guillot, A.; Six, D.; Rabatel, A.; Arnaud, Y.

2012-12-01

163

Glacier area and length changes in Norway from repeat inventories  

NASA Astrophysics Data System (ADS)

In this study, we assess glacier area and length changes in mainland Norway from repeat Landsat TM/ETM+-derived inventories and digitized topographic maps. The multi-temporal glacier inventory consists of glacier outlines from three time ranges: 1947 to 1985 (GIn50), 1988 to 1997 (GI1990), and 1999 to 2006 (GI2000). For the northernmost regions, we include an additional inventory (GI1900) based on historic maps surveyed between 1895 and 1907. Area and length changes are assessed per glacier unit, 36 subregions, and for three main parts of Norway: southern, central, and northern. The results show a decrease in the glacierized area from 2994 km2 in GIn50 to 2668 km2 in GI2000 (total 2722 glacier units), corresponding to an area reduction of -326 km2, or -11% of the initial GIn50 area. The average length change for the full epoch (within GIn50 and GI2000) is -240 m. Overall, the comparison reveals both area and length reductions as general patterns, even though some glaciers have advanced. The three northernmost subregions show the highest retreat rates, whereas the central part of Norway shows the lowest change rates. Glacier area and length changes indicate that glaciers in maritime areas in southern Norway have retreated more than glaciers in the interior, and glaciers in the north have retreated more than southern glaciers. These observed spatial trends in glacier change are related to a combination of several factors such as glacier geometry, elevation, and continentality, especially in southern Norway.

Winsvold, S. H.; Andreassen, L. M.; Kienholz, C.

2014-10-01

164

A data set of worldwide glacier length fluctuations  

NASA Astrophysics Data System (ADS)

Glacier fluctuations contribute to variations in sea level and historical glacier length fluctuations are natural indicators of past climate change. To study these subjects, long-term information of glacier change is needed. In this paper we present a data set of global long-term glacier length fluctuations. The data set is a compilation of available information on changes in glacier length worldwide, including both measured and reconstructed glacier length fluctuations. All 471 length series start before 1950 and cover at least four decades. The longest record starts in 1535, but the majority of time series start after 1850. The number of available records decreases again after 1962. The data set has global coverage including records from all continents. However, the Canadian Arctic is not represented in the data set. The available glacier length series show relatively small fluctuations until the mid-19th century, followed by a global retreat. The retreat was strongest in the first half of the 20th century, although large variability in the length change of the different glaciers is observed. During the 20th century, calving glaciers retreated more than land-terminating glaciers, but their relative length change was approximately equal. Besides calving, the glacier slope is the most important glacier property determining length change: steep glaciers have retreated less than glaciers with a gentle slope.

Leclercq, P. W.; Oerlemans, J.; Basagic, H. J.; Bushueva, I.; Cook, A. J.; Le Bris, R.

2014-04-01

165

Glaciers in the Earth's Hydrological Cycle: Assessments of Glacier Mass and Runoff Changes on Global and Regional Scales  

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 meltwater is an important contributor to and modulator of river flow. In light of strongly accelerated worldwide glacier retreat, the associated glacier mass losses raise concerns over the sustainability of water supplies in many parts of the world. Here, we review recent attempts to quantify glacier mass changes and their effect on river runoff on regional and global scales. We find that glacier runoff is defined ambiguously in the literature, hampering direct comparison of findings on the importance of glacier contribution to runoff. Despite consensus on the hydrological implications to be expected from projected future warming, there is a pressing need for quantifying the associated regional-scale changes in glacier runoff and responses in different climate regimes.

Radi?, Valentina; Hock, Regine

2014-05-01

166

What Influences Climate and Glacier Change in the Southwestern China?  

NASA Technical Reports Server (NTRS)

The subject of climate change in the areas of the Tibetan Plateau (TP) and the Himalayas has taken on increasing importance because of available water resources from their mountain glaciers. Many of these glaciers over the region have been retreating, while some are advancing and stable. Other studies report that some glaciers in the Himalayas show acceleration on their shrinkage. However, the causes of the glacier meltings are still difficult to grasp because of the complexity of climatic change and its influence on glacier issues. However, it is vital that we pursue further study to enable the future prediction on glacier changes.

Yasunari, Teppei J.

2012-01-01

167

Decay of a long-term monitored glacier: Careser Glacier (Ortles-Cevedale, European Alps)  

NASA Astrophysics Data System (ADS)

The continuation of valuable, long-term glacier observation series is threatened by the accelerated mass loss which currently affects a large portion of so-called "benchmark" glaciers. In this work we present the evolution of the Careser Glacier, from the beginning of systematic observation at the end of the 19th century to its current condition in 2012. In addition to having one of the longest and richest observation records among the Italian glaciers, Careser is unique in the Italian Alps for its 46 yr mass balance series that started in 1967. In the present study, variations in the length, area and volume of the glacier since 1897 are examined, updating and validating the series of direct mass balance observations and adding to the mass balance record into the past using the geodetic method. The glacier is currently strongly out of balance and in rapid decay; its average mass loss rate over the last 3 decades was 1.5 m water equivalent per year, increasing to 2.0 m water equivalent per year in the last decade. Although these rates are not representative at a regional scale, year-to-year variations in mass balance show an unexpected increase in correlation with other glaciers in the Alps, during the last 3 decades. If mass loss continues at this pace, the glacier will disappear within a few decades, putting an end to this unique observation series.

Carturan, L.; Baroni, C.; Becker, M.; Bellin, A.; Cainelli, O.; Carton, A.; Casarotto, C.; Dalla Fontana, G.; Godio, A.; Martinelli, T.; Salvatore, M. C.; Seppi, R.

2013-12-01

168

Glacier acceleration, glacial earthquakes, and ice loss at Helheim Glacier, Greenland  

Microsoft Academic Search

Satellite observations during the last decade have shown dramatic changes in flow speed at Greenland's outlet glaciers, often accompanied by retreats of several km in calving-front location and increasing numbers of glacial earthquakes. Geodetic, seismological, and oceanographic data collected as part of a multidisciplinary field experiment at Helheim Glacier, East Greenland, over three summer seasons (2006--2008), together with satellite imagery,

M. Nettles; T. B. Larsen; P. Elsegui; G. S. Hamilton; L. A. Stearns; A. P. Ahlstrm; J. L. Davis; M. L. Andersen; J. de Juan; S. A. Khan; L. Stenseng; G. Ekstrm; R. Forsberg; K. M. Schild

2008-01-01

169

Impacts of climate warming on alpine glacier tourism and adaptive measures: A case study of Baishui Glacier No. 1 in Yulong Snow Mountain, Southwestern China  

Microsoft Academic Search

Alpine glaciers usually feature with best hydrothermal condition in mountain climate, and present beautiful glacier scenery,\\u000a various glacier landforms, rich biodiversity, and easier accessibility, compared with continental glaciers or ice sheets.\\u000a Nevertheless, Alpine glaciers are more sensitive to climate warming, and climate warming has seriously affected Alpine glaciers\\u000a and surrounding environment. The quality and attractiveness of Alpine glaciers to tourism

Shijin Wang; Yuanqing He; Xiaodong Song

2010-01-01

170

Evaluating the performance of a glacier erosion model applied to Peyto Glacier, Alberta, Canada  

NASA Astrophysics Data System (ADS)

Glaciers are effective agents of erosion for many mountainous regions, but primary rates of erosion are difficult to quantify due to unknown conditions at the glacier bed. We develop a numerical model of subglacial erosion and passively couple it to a vertically integrated ice flow model (UBC regional glaciation model). The model accounts for seasonal changes in water pressure at the glacier bed which affect rates of abrasion and quarrying. We apply our erosion model to Peyto Glacier, and compare estimates of glacier erosion to the mass of fine sediment contained in a lake immediately down valley from the glacier. A series of experiments with our model and ones based on subglacial sliding rates are run to explore model sensitivity to bedrock hardness, seasonal hydrology, changes in mass balance, and longer-term dimensional changes of the glacier. Our experiments show that, as expected, erosion rates are most sensitive to bedrock hardness and changes in glacier mass balance. Silt and clay contained in Peyto Lake primarily originate from the glacier, and represent sediments derived from abrasion and comminution of material produced by quarrying. Average specific sediment yield during the period AD1917-1970 from the lake is 467190 Mg km-2yr-1 and reaches a maximum of 928 Mg km-2yr-1 in AD1941. Converting to a specific sediment yield, modelled average abrasion and quarrying rates during the comparative period are 14244 Mg km-2yr-1 and 1167213 Mg km-2yr-1 respectively. Modelled quarrying accounts for approximately 85-95% of the erosion occurring beneath the glacier. The basal sliding model estimates combined abrasion and quarrying. During the comparative period, estimated yields average 427136 Mg km-2yr-1, lower than the combined abrasion and quarrying models. Both models predict maximum sediment yield when Peyto Glacier reached its maximum extent. The simplistic erosion model shows higher sensitivity to climate, as seen by accentuated sediment yield peaks during the Little Ice Age. In all of our experiments to date, modelled sediment yield closely follow maximum ice cover. In contrast, sediment yields obtained from the lake indicate that maximum sediment delivery to the lake lagged maximum ice cover and occurred during a period of rapid glacier retreat. We interpret this lag to indicate removal of stored sediments beneath the glacier and subaerial erosion from recently exposed sediments in the glacier forefield rather than an increase in primary erosion of bedrock.

Vogt, R.; Mlynowski, T. J.; Menounos, B.

2013-12-01

171

High Altitude Climate: Observations From the Baltoro Glacier, Karakoram Himalaya, Pakistan  

NASA Astrophysics Data System (ADS)

Few atmospheric observations have been recorded from the Karakoram Himalaya. Fieldwork in the summer of 2005 was conducted along the Baltoro and Godwin-Austen Glaciers in the vicinity of K2. Measurements were made of atmospheric ozone, carbon dioxide, humidity, temperature, and winds along the glaciers leading to K2. Over the debris-covered Baltoro glacier, at altitudes well above any vegetated region, there is a distinct diurnal cycle in atmospheric carbon dioxide that may be related to weathering processes. During the 5 weeks spent on the glaciers there was one high ozone event recorded that marks the presence of stratospheric air with levels reaching 0.18 ppm. The synoptic event that generated these high ozone levels in the region is visibile from TOMS satellite data and is likely a tropopause fold event associated with baroclinic instability of the midlatitude jet stream. The fact that high ozone levels can (and did) trigger a number of respiratory illnesses suggests that individuals working in high altitudes should be aware of the processes that lead to stratosphere-troposphere mixing. Keywords: ozone, carbon dioxide, troposphere-stratosphere mixing, tropopause fold, diurnal cycle

Bush, A. B.

2005-12-01

172

Analysis of meteorological data and the surface energy balance of Keqicar Glacier, Tien Shan, China  

NASA Astrophysics Data System (ADS)

Northwestern China currently experiences a climate change with fundamental consequences for the hydrological cycle. In the strongly arid region where water resources are essential for agriculture and food production, glaciers represent important water resources, contributing significantly to streamflow. The debris is an important glaciological feature of the region and has major impact on melt rates. It is essential to understand and quantify the interaction of climate and sub-debris melt in order to assess the current situation and to predict future water yield. Note that the surface energy balance determines glacier melt. However, little is known about the variability characteristics of the surface energy fluxes in this region. For this reason, we set up two automatic weather stuation (AWSs) in the ablation area of Keqicar Glacier. Keqicar Glacier is located in the Tarim River basin (largest inland river basin in China), southwestern Tien Shan, China. It is a representative debris-covered glacier with a length of 26.0 km and a total surface area of 83.6 km2. The thickness of the debris layer varies from 0.0 to 2.50 m in general. In some places large rocks are piled up to several meters. In this study, we report on analysis of meteorological data for the period 1 July-13 September 2003, from two automatic weather stations, aimed at studying the relationship between climate and ablation. One station is located on the lower part of the ablation area where the glacier is covered by debris layer, and the other near the equilibrium line altitude (ELA). All sensors were sampled every 10 seconds, and data were stored as hourly averages. The stations were visited regularly for maintenance at two weeks intervals depending on the weather conditions and location of the AWS. A total of 17 ablation stakes were drilled into the glacier at different elevations to monitor glacier melt during the study period. Readings were taken regularly in connection with AWS maintenance. The weather station on the glacier measured an average temperature of 2.6 C (at 2m height above surface). The lapse rate of air temperature is close to the standard free atmospheric lapse rate (0.6 C per 100m), which shows the cold effect of glacier is not significant. The local mountain-valley winds is significant, the speed of which is 2.3 m s-1 (at 2m height). Glacier is dominated by the convectional precipitation, 75% of which occurs in day time. The ablation stakes indicate a specific mass balance of -2.5 m w.e. between 1 July and 13 September. The specific mass balance calculated from the surface energy balance, -2.6 m w.e., is in close correspondence to this. The thermal processes on the debris layer are quite different from those on bare ice or snow. The main physical characteristics of the debris layer are the thermal conductivity and albedo that control heat conduction to the ice-debris interface. Net radiation is the main melt energy whether the debris layer is taken into consideration or not, which is lager between July and the middle of August, and then decreases. This is coincides with the glacier ablation. On the debris-covered area, the sensible- and latent-heat fluxes contribute 19.6% of the melt energy, higher than that on the debris-free ice (4.1%). Hence, due to the existing debris layer, the ablation shows a significant spatial distribution.

Zhang, Y.; Liu, S.; Fujita, K.; Han, H.; Li, J.

2009-04-01

173

The History of the Glacier Facies Concept  

NASA Astrophysics Data System (ADS)

The concept of glacier facies developed as a result of physical measurements made in Greenland on repeated traverses that went inland from the west coast at two latitudes (77 N and 70 N) and north to south along the crest of the ice sheet. Snow pits and shallow cores showed discontinuities in physical characteristics that defined the facies boundaries. Some refinement have resulted from research in Antarctica and on Alaskan mountain glaciers. Thirty years after the facies were defined, based on field measurements, it was found that radar data (SAR) from satellites show the boundary between the percolation and dry snow facies in Greenland. They also show the percolation facies of the Greenland ice sheet to be the brightest radar reflector on earth. The dry snow facies is rare except on the major ice sheets (Greenland and Antarctica), but it is present on mountains that exceed 4000 m in Alaska and the Yukon. In particular, Mt. Wrangell, Alaska was selected for continued study of glacier facies because it has a large and accessible area above 4000 m. Mt. Wrangell has proven to have the full spectrum of glacier facies, and these can be seen on the SAR map of Alaska. Refinements in the definition of the lower end of the wet snow facies, to deal with a slush zone and a superimposed ice zone, resulted from Fritz Mueller's research on Axel Heiberg Island and from studies on the McCall Glacier of Alaska. Minor refinements in defining the dry snow facies resulted from comparing Antarctica and Greenland in places where mean annual temperature and accumulation rates were essentially equal. The glacier facies concept also provides a way of comparing the two polar regions and of speculating on the glacier facies that existed on the Pleistocene continental ice sheets.

Benson, C. S.

2001-12-01

174

Linking glacier annual mass balance and glacier albedo from MODIS data  

NASA Astrophysics Data System (ADS)

The albedo is one of the variables controlling the mass balance of temperate glaciers. Multispectral imagers, such as MODIS on board TERRA and AQUA, provide a means to monitor glacier albedo. In this study, different methods to retrieve broadband glacier albedo from MODIS data are compared. In particular, the effect of the multiple reflections due to the rugged topography and that of the anisotropic reflection of snow and ice are investigated. The methods are tested on the Saint Sorlin glacier (Grandes Rousses area, French Alps). The accuracy of the retrieved albedo is estimated using both field measurements and albedo derived from terrestrial photographs. The root mean square deviation between field measurements and the broadband albedo retrieved from MODIS pixels at 250m spatial resolution was found to be less than 0.06. One decade (2000-2010) of MODIS data were then processed to create a time series of albedo maps of Saint Sorlin glacier during the ablation season. It appears that the albedo in the ablation area of the glacier does not exhibit any marked decreasing trend during the decade under study. This contrasts with the situation observed on other glaciers in the Alps. In addition, the annual mass balance of Saint Sorlin Glacier was compared with the minimum albedo value (spatial averaged over the whole glacier) observed with MODIS during the ablation season. A high linear correlation exists between the two variables. Furthermore, the day on which the albedo reaches a minimum over the glacier closely corresponds to the day on which the snowline is found to be at its highest elevation, thus close to the glacier's equilibrium line. This indicates that the high correlation can be explained by the fact that this minimal albedo contains a high degree of information regarding the relative share of areal surfaces between the ablation zone (i.e., ice with a generally lower albedo) and the accumulation zone (i.e., snow with a relatively high albedo). This implies that monitoring the albedo of glacier with MODIS data can provide a useful means to approach the inter-annual variability of the glacier's mass balance.

Dumont, M.; Gardelle, J.; Arnaud, Y.; Guillot, A.; Sirguey, P.; Six, D.

2012-04-01

175

Glaciological investigations beneath an active polar glacier  

NASA Astrophysics Data System (ADS)

Meserve Glacier, Antarctica, was used as a natural laboratory for research on the effective viscosity of subfreezing polycrystalline ice, and on the interaction of cold-based glaciers with their beds. A tunnel was excavated through basal layers of this glacier, which allowed sampling of ice for subsequent measurements of physical and chemical properties and allowed in-situ measurements of ice deformation and glacier sliding. Analyses of deformation reveal a direct dependence of strain rate on crystal size, which reflects an important role for grain-size-sensitive deformation mechanisms such as grain boundary sliding. The sensitivity of strain rate to chemical impurity content and rock particle content is found to be very low. Variations of crystal size probably are an important control on shear enhancement in the ice sheets. The enhanced shear strain rate inferred from tilt of the Dye 3 borehole can be explained as a result of combined fabric and crystal size variations. I infer that interactions between Meserve glacier and its bed are influenced by the presence of liquid water films at ice-rock interfaces despite the low temperature of -17C. Such films allow slip at ice-rock interfaces and cause in-situ segregation of ice into clean lenses amidst dirty layers. Using slip rate and bed surface roughness measurements I infer la liquid film thickness of at least tens of nanometers. Such films should generally be present in polar glaciers, and will have a thickness controlled by soluble impurities and temperature. Analyses of gas and isotopic composition of basal ices reveal that entrainment of bed material into this glacier actively occurs without bulk freeze-on and conventional regelation. Cold-based glaciers have the capacity to striate and erode their beds, and to create glacial landforms. I reinterpret the clear and persistent relationship between d18O and dD of polar precipitation, which allows isotopic composition to be an important tool for studying glacier-bed interactions and deuterium excess measurements on ice cores to reveal subtropical paleoclimate. I argue that the isotopic composition of precipitation is determined by water-vapor equilibrium to temperatures as low as -35C. This implies deuterium excess is not sensitive to cloud supersaturation.

Cuffey, Kurt Marshall

176

Mathematical challenges in glacier modeling (Invited)  

NASA Astrophysics Data System (ADS)

Many of Earth's glaciers are currently shrinking and it is expected that this trend will continue as global warming progresses. To virtually reproduce the evolution of glaciers and finally to predict their future, one needs to couple models of different disciplines and scales. Indeed, the slow motion of ice is described by fluid mechanics equations while the daily snow precipitations and melting are described by hydrological and climatic models. Less visible, applied mathematics are essential to run such a coupling at two different levels: by solving numerically the underlying equations and by seeking parameters using optimisation methods. This talk aims to make visible the role of mathematics in this area. I will first present a short educational film I have made for the "Mathematics of Planet Earth 2013", which is an introduction to the topic. To go further, solving the mechanical model of ice poses several mathematical challenges due to the complexity of the equations and geometries of glaciers. Then, I will describe some strategies to deal with such difficulties and design robust simulation tools. Finally, I will present some simulations of the largest glacier of the European Alps, the Aletsch glacier. As a less unexpected application, I will show how these results allowed us to make a major advance in a police investigation started in 1926.

jouvet, G.

2013-12-01

177

Exploration of Uncertainty in Glacier Modelling  

NASA Technical Reports Server (NTRS)

There are procedures and methods for verification of coding algebra and for validations of models and calculations that are in use in the aerospace computational fluid dynamics (CFD) community. These methods would be efficacious if used by the glacier dynamics modelling community. This paper is a presentation of some of those methods, and how they might be applied to uncertainty management supporting code verification and model validation for glacier dynamics. The similarities and differences between their use in CFD analysis and the proposed application of these methods to glacier modelling are discussed. After establishing sources of uncertainty and methods for code verification, the paper looks at a representative sampling of verification and validation efforts that are underway in the glacier modelling community, and establishes a context for these within overall solution quality assessment. Finally, an information architecture and interactive interface is introduced and advocated. This Integrated Cryospheric Exploration (ICE) Environment is proposed for exploring and managing sources of uncertainty in glacier modelling codes and methods, and for supporting scientific numerical exploration and verification. The details and functionality of this Environment are described based on modifications of a system already developed for CFD modelling and analysis.

Thompson, David E.

1999-01-01

178

ICESat Observations of Southern Alaska Glaciers  

NASA Technical Reports Server (NTRS)

In late February and March, 2003, the Ice, Cloud, and land Elevation Satellite (ICESat) measured ice and land elevations along profiles across southern Alaska. During this initial data acquisition stage ICESat observations were made on 8-day repeat tracks to enable calibration and validation of the ICESat data products. Each profile consists of a series of single point values derived from centroid elevations of an $\\approx$70 m diameter laser footprint. The points are s4pakated by $\\approx$172 m along track. Data siets of 8-day observations (an ascending and descending ground track) crossed the Bering and Malaspina Glacier. Following its 1993--1995 surge; the Bering Glacier has undergone major terminus retreat as well as ike thinning in the abtation zone. During the later part of the 20th century, parts of the Malaspina thinned by about 1 m/yr. The multiple observation profiles across the Bering and Malaspina piedmont lobes obtained in February/March are being geolocated on Landsat images and the elevation profiles will be used for a number o scientific objectives. Based on our simulations of ICESat performance over the varied ice surface of the Jakobshavn Glacier of GReenland, 2003, we expect to measure annual, and possibly seasonal, ice elevation changes on the large Alaskan glaciers. Using elevation data obtained from a second laser, we plan to estimate ice elevation changes on the Bering Glacier between March and October 2003.

Sauber, Jeanne; Molnia, Bruce F.; Mitchell, Darius

2003-01-01

179

The influence of air temperature inversions on snowmelt and glacier mass-balance simulations, Ammassalik island, SE Greenland  

SciTech Connect

In many applications, a realistic description of air temperature inversions is essential for accurate snow and glacier ice melt, and glacier mass-balance simulations. A physically based snow-evolution modeling system (SnowModel) was used to simulate eight years (1998/99 to 2005/06) of snow accumulation and snow and glacier ice ablation from numerous small coastal marginal glaciers on the SW-part of Ammassalik Island in SE Greenland. These glaciers are regularly influenced by inversions and sea breezes associated with the adjacent relatively low temperature and frequently ice-choked fjords and ocean. To account for the influence of these inversions on the spatiotemporal variation of air temperature and snow and glacier melt rates, temperature inversion routines were added to MircoMet, the meteorological distribution sub-model used in SnowModel. The inversions were observed and modeled to occur during 84% of the simulation period. Modeled inversions were defined not to occur during days with strong winds and high precipitation rates due to the potential of inversion break-up. Field observations showed inversions to extend from sea level to approximately 300 m a.s.l., and this inversion level was prescribed in the model simulations. Simulations with and without the inversion routines were compared. The inversion model produced air temperature distributions with warmer lower elevation areas and cooler higher elevation areas than without inversion routines due to the use of cold sea-breeze base temperature data from underneath the inversion. This yielded an up to 2 weeks earlier snowmelt in the lower areas and up to 1 to 3 weeks later snowmelt in the higher elevation areas of the simulation domain. Averaged mean annual modeled surface mass-balance for all glaciers (mainly located above the inversion layer) was -720 {+-} 620 mm w.eq. y{sup -1} for inversion simulations, and -880 {+-} 620 mm w.eq. y{sup -1} without the inversion routines, a difference of 160 mm w.eq. y{sup -1}. The annual glacier loss for the two simulations was 50.7 x 10{sup 6} m{sup 3} y{sup -1} and 64.4 x 10{sup 6} m{sup 3} y{sup -1} for all glaciers - a difference of {approx}21%. The average equilibrium line altitude (ELA) for all glaciers in the simulation domain was located at 875 m a.s.l. and at 900 m a.s.l. for simulations with or without inversion routines, respectively.

Mernild, Sebastian Haugard [Los Alamos National Laboratory; Liston, Glen [COLORADO STATE UNIV.

2009-01-01

180

Satellite image atlas of glaciers of the world  

USGS Publications Warehouse

The world's glaciers react to and interact with changes in global and regional climates. Most mountain glaciers worldwide have been retreating since the latter part of the 19th century; global sea level has risen about 10 centimeters during the past century. Glaciers vary in size as a result of several factors, of which climate variation is probably the most important. The reasons we are interested in glacier variation include its connection to climate change and to global sea level.

U.S. Geological Survey

1994-01-01

181

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.

Starr, Cindy; Strong, Jim; Oneil, Pamela; Acuna, Andy; Hall, Dorothy; Benson, Carl

1996-02-23

182

Antarctic glaciers shrinking due to ice shelf collapse  

NSDL National Science Digital Library

Mass and velocity measurements taken from satellites and airplanes between 1995 and 2004 were studied to determine if glaciers on the West Antarctic Peninsula were growing or shrinking. It was found that loss of glacier mass from melting and movement into the ocean exceeded snowfall accumulation for several glaciers on the peninsula. The authors propose that as the region continues to warm, the Wordie Bay glaciers will melt more quickly, causing sea level to rise.

Al., Rignot E.; Agu

183

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

184

Logistic regression modeling of rock glacier and glacier distribution: Topographic and climatic controls in the semi-arid Andes  

NASA Astrophysics Data System (ADS)

Logistic regression is applied to a random sample of surface points in the semi-arid Andes of Santiago and Mendoza (Chile/Argentina, 32 45'-34 30' S, 12 000 km 2 above 3000 m a.s.l.) to identify local and regional controls on rock glacier and glacier distribution. The study area is among the areas with the greatest abundance of rock glaciers worldwide. The explanatory variables used for model selection are related to local and regional morphometric and climatic characteristics. The models achieve a very good fit (area under the ROC curve 0.84 for rock glaciers and 0.95 for glaciers) and are able to reproduce the regional distribution pattern. Model results are used to determine the optimal morphographic and climatic niche of rock glaciers and glaciers in the study area, and help explain the presence of low-elevation rock glaciers under favorable topoclimatic conditions.

Brenning, Alexander; Trombotto, Dario

2006-11-01

185

Subglacial melting of glaciers by catchment streams is a missing link in temperate glacier mass balance  

NASA Astrophysics Data System (ADS)

The influence of snowmelt and rain water on subglacial hydrology and glacier mass balance of temperate valley glaciers is poorly understood. We present a thermo-hydraulic melt model to improve understanding of the potential influence that streams sourced from snowmelt and rain have on the subglacial hydrology and melting of the high-precipitation Franz Josef Glacier, New Zealand. The model simulates conduit expansion due to melting caused by heat advection and contraction to due ice deformation at an hourly time-step to obtain an annual melt rate along the length of individual subglacial conduits fed from terrestrial streams that enter the glacier from the ice-free sub-catchments surrounding it. These streams are fed by snowmelt and rainfall that enter the glacier well above 0C (up to ~10C at low altitudes). Our model is calibrated using terrestrial stream temperature data and is validated with field measurements of surface and proglacial meltwater temperatures, as well as internal water flow velocities. Modelled outputs based on the best available data from measurements and observations indicate that streams entering the Franz Josef Glacier contribute an estimated 7% to the total glacier melt. This is the equivalent of more than twice the surface rainfall heat flux, which shows that rain and snowmelt may melt significant quantities of ice within a glacier. Not accounting for this melting mechanism in glaciological models where streams enter glaciers may lead to: 1) an incorrect characterisation of the subglacial hydrological drainage system; and 2) a potentially serious bias error in mass balance estimations. The second implication is fundamentally important for model robustness given that glaciological models are increasingly being used to predict the effects of future climate change.

Alexander, David; Shulmeister, James; Davies, Tim; Callow, Nik

2013-04-01

186

Losing a Legacy: A photographic story of disappearing glaciers  

E-print Network

Losing a Legacy: A photographic story of disappearing glaciers W.C. Alden photo, GNP Archives B and into the existing forest, bulldozing down trees and creating a "trimline". During the drought between 1917 and 1941 of the earliest photographs repeated from Glacier Park that shows the disappearance of glacier ice and helped

187

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

188

WATER FLOW THROUGH TEMPERATE GLACIERS Andrew G. Fountain1  

E-print Network

WATER FLOW THROUGH TEMPERATE GLACIERS Andrew G. Fountain1 Department of Geology Portland State, Washington Abstract. Understanding water movement through a glacier is fundamental to several critical issues glacierized drainage basins. To this end we have synthesized a conceptual model of water movement through

Fountain, Andrew G.

189

Rock glacier monitoring with low-cost GPS  

E-print Network

Rock glacier monitoring with low-cost GPS: Case study at Dirru glacier, Mattertal Dr. Philippe, Switzerland 05.11.2009 #12;2Goal Description of GPS test network for rock glacier monitoring Data processing & preliminary results - accuracy ? Conclusions & outlook Contents Investigate the potential of low-cost GPS

190

The Role of Glaciers in the Hydrology of Nepal (Invited)  

Microsoft Academic Search

Glaciers are a component of the hydrologic regime of many large mountain ranges of the world, including the Himalaya. However, the hydrologic regime of Himalayan catchment basins and the role of glaciers in the hydrologic regime of this region are not well understood. Current concern regarding the impact of the retreat of Himalayan glaciers on water supplies poses an urgent

R. L. Armstrong; A. Racoviteanu; D. Alford

2010-01-01

191

Subpolar glaciers network as natural sensors of global warming evolution  

Microsoft Academic Search

In the expeditions carried out both to temperate and subpolar glaciers in both hemispheres, we have observed the existence of endoglacier and subglacier flows and drainages also in subpolar glaciers. Our main work hypothesis is centred on investigating the role played by subpolar glacier discharge in global warming, as we consider this discharge may represent that unknown third of sea

Adolfo Eraso

192

Streamflow response of partially glacierized river basins to glacier recession using a coupled glacio-hydrological model  

NASA Astrophysics Data System (ADS)

Despite the well publicized risk posed by declining glaciers to water supply in partially glacierized high mountain river systems, our ability to accurately predict the sensitivity of the runoff contribution from glaciers in these basins is limited. Modeling the effect of glacier changes on streamflow in such river basins is complicated by limited meteorological and glaciological data, and by the fact that areas subject to glacier retreat often transition to seasonally ephemeral snow cover. To represent these effects accurately, glacier dynamics must be represented explicitly in hydrological models. Here, we describe the integration of the physically based spatially distributed University of British Columbia glacier dynamics model into the widely used Distributed Hydrology-Soil-Vegetation Model (DHSVM) in order to investigate the effect of glacier recession on streamflow dynamics. The integrated model was used to simulate glacier and streamflow dynamics in five test river basins globally where the effects of declining glacier extent on water supply is of concern: the Upper Bow River basin in the Western Canada, the Llanganuco Basin in the Cordillera Blanca, Peru, the Zongo glacier basin in the Cordillera Real, Bolivia, the Dongkemadi River Basin in the Tibetan Plateau region and the Astore River basin in the Western Himalayas. We tested the coupled glacio-hydrologic model performance through comparison of predicted variations in glacier extent, snow water equivalent and streamflow discharge, using satellite-derived glacier/snow cover and measured discharge and snow data. Evaluation of our model predictions confirms that representation of glacier cover changes as result of glacier dynamics reduces errors in streamflow simulations in these basins. Subsequently, we evaluate the effects of changing glacier extent on seasonal low flows (to which water supply is most sensitive) in each of the river basins.

Naz, B. S.; Frans, C. D.; Burns, P. J.; Cuo, L.; Duan, K.; Clarke, G. K.; Nolin, A. W.; Istanbulluoglu, E.; Lettenmaier, D. P.

2012-12-01

193

ASTER Imaging and Analysis of Glacier Hazards  

NASA Astrophysics Data System (ADS)

Most scientific attention to glaciers, including ASTER and other satellite-derived applications in glacier science, pertains to their roles in the following seven functions: (1) as signposts of climate change (Kaser et al. 1990; Williams and Ferrigno 1999, 2002; Williams et al. 2008; Kargel et al. 2005; Oerlemans 2005), (2) as natural reservoirs of fresh water (Yamada and Motoyama 1988; Yang and Hu 1992; Shiyin et al. 2003; Juen et al. 2007), (3) as contributors to sea-level change (Arendt et al. 2002), (4) as sources of hydropower (Reynolds 1993); much work also relates to the basic science of glaciology, especially (5) the physical phenomenology of glacier flow processes and glacier change (DeAngelis and Skvarca 2003; Berthier et al. 2007; Rivera et al. 2007), (6) glacial geomorphology (Bishop et al. 1999, 2003), and (7) the technology required to acquire and analyze satellite images of glaciers (Bishop et al. 1999, 2000, 2003, 2004; Quincey et al. 2005, 2007; Raup et al. 2000, 2006ab; Khalsa et al. 2004; Paul et al. 2004a, b). These seven functions define the important areas of glaciological science and technology, yet a more pressing issue in parts of the world is the direct danger to people and infrastructure posed by some glaciers (Trask 2005; Morales 1969; Lliboutry et al. 1977; Evans and Clague 1988; Xu and Feng 1989; Reynolds 1993, 1998, 1999; Yamada and Sharma 1993; Hastenrath and Ames 1995; Mool 1995; Ames 1998; Chikita et al. 1999; Williams and Ferrigno 1999; Richardson and Reynolds 2000a, b; Zapata 2002; Huggel et al. 2002, 2004; Xiangsong 1992; Kb et al. 2003, 2005, 2005c; Salzmann et al. 2004; Noetzli et al. 2006).

Kargel, Jeffrey; Furfaro, Roberto; Kaser, Georg; Leonard, Gregory; Fink, Wolfgang; Huggel, Christian; Kb, Andreas; Raup, Bruce; Reynolds, John; Wolfe, David; Zapata, Marco

194

Melting Himalayan Glaciers May Doom Towns  

NSDL National Science Digital Library

This news article describes how mountain lakes in Nepal and Bhutan have become so overfilled by water from melting glaciers that they are in danger of overflowing. Scientists from the United Nations Environment Program (UNEP), along with remote-sensing experts from the International Center for Integrated Mountain Development (ICIMOD), predict that in the next half decade or so, the Himalayas could experience intense flooding as mountain lakes overflow with water from glaciers and snowfields which are melting as a result of gradually rising global temperatures.

195

The application of glacier inventory data for estimating past climate change effects on mountain glaciers: A comparison between the  

E-print Network

. Introduction The last report of the Intergovernmental Panel on Climate Change (IPCC, 2001) stated that glaciersThe application of glacier inventory data for estimating past climate change effects on mountain are the best natural indicators of climate. Hence, glacier changes are observed world wide within the framework

196

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

Microsoft Academic Search

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,

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

2009-01-01

197

Glacier volume response time and its links to climate and topography based on a conceptual model of glacier hypsometry  

NASA Astrophysics Data System (ADS)

Glacier volume response time is a measure of the time taken for a glacier to adjust its geometry to a climate change. It is currently believed that the volume response time is given approximately by the ratio of glacier thickness to ablation at the glacier terminus. We propose a new conceptual model of glacier hypsometry (area-altitude relation) and derive the volume response time where climatic and topographic parameters are separated. The former is expressed by mass balance gradients which we derive from glacier-climate modelling and the latter are quantified with data from the World Glacier Inventory. Aside from the well-known scaling relation between glacier volume and area, we establish a new scaling relation between glacier altitude range and area, and evaluate it for seven regions. The presence of this scaling parameter in our response time formula accounts for the mass balance elevation feedback and leads to longer response times than given by the simple ratio of glacier thickness to ablation. Volume response times range from decades to thousands of years for glaciers in maritime (wet-warm) and continental (dry-cold) climates, respectively. The combined effect of volume-area and altitude-area scaling relations is such that volume response time can increase with glacier area (Axel Heiberg Island and Svalbard), hardly change (Northern Scandinavia, Southern Norway and the Alps) or even get smaller (The Caucasus and New Zealand).

Raper, S. C. B.; Braithwaite, R. J.

2009-03-01

198

Glacier volume response time and its links to climate and topography based on a conceptual model of glacier hypsometry  

NASA Astrophysics Data System (ADS)

Glacier volume response time is a measure of the time taken for a glacier to adjust its geometry to a climate change. It has been previously proposed that the volume response time is given approximately by the ratio of glacier thickness to ablation at the glacier terminus. We propose a new conceptual model of glacier hypsometry (area-altitude relation) and derive the volume response time where climatic and topographic parameters are separated. The former is expressed by mass balance gradients which we derive from glacier-climate modelling and the latter are quantified with data from the World Glacier Inventory. Aside from the well-known scaling relation between glacier volume and area, we establish a new scaling relation between glacier altitude range and area, and evaluate it for seven regions. The presence of this scaling parameter in our response time formula accounts for the mass balance elevation feedback and leads to longer response times than given by the simple ratio of glacier thickness to ablation at the terminus. Volume response times range from decades to thousands of years for glaciers in maritime (wet-warm) and continental (dry-cold) climates respectively. The combined effect of volume-area and altitude-area scaling relations is such that volume response time can increase with glacier area (Axel Heiberg Island and Svalbard), hardly change (Northern Scandinavia, Southern Norway and the Alps) or even get smaller (The Caucasus and New Zealand).

Raper, S. C. B.; Braithwaite, R. J.

2009-08-01

199

Geodetic observations of short-time-scale changes in glacier flow at Helheim and Kangerdlugssuaq Glaciers, East Greenland  

Microsoft Academic Search

Evidence obtained by several workers during the past few years has shown that the major outlet glaciers in Greenland can both accelerate and decelerate more rapidly than previously appreciated. Some abrupt accelerations at the largest outlet glaciers, including Jakobshavn Isbrae and Helheim and Kangerdlugssuaq Glaciers, have been linked to large-scale calving events and glacial earthquakes (Nettles et al., 2008; Amundson

M. Nettles; P. Elosegui; T. Larsen; J. L. Davis; G. S. Hamilton; L. A. Stearns; M. L. Andersen; J. de Juan; E. Malikowski; I. Gonzalez; M. Okal; B. Johns; G. Ekstrom; A. Ahlstrm; L. Stenseng; S. A. Khan; K. M. Schild; R. Forsberg; S. A. Veitch

2009-01-01

200

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

201

Surface slope control on firn density at Thwaites Glacier, West Antarctica: Results from airborne radar sounding  

NASA Astrophysics Data System (ADS)

derive the surface density variations over Thwaites Glacier from a statistical analysis of airborne High-Capability Radar Sounder surface returns acquired in the 2004-2005 summer. We produce a 5 km gridded map with an estimated 12.5 kg m-3 accuracy. The background pattern of densities decreases inland from ~ 480 kg m-3 to ~ 350 kg m-3. A remarkable ~ 30 km wide vein-shaped anomaly of up to 570 kg m-3 is located ~ 100 km from the coastline. Density anomalies correspond with surface slope breaks but are not necessarily coincident with smaller slopes. They could result from complex wind-driven snow redistribution and/or refreezing of former snowmelt. This inversion technique can significantly improve surface mass balance calculations to understanding of glacier dynamics at regional scales and is valuable to verify and improve Antarctic climate models. It is also a promising approach for future surface analysis of icy moons by planetary radars.

Grima, Cyril; Blankenship, Donald D.; Young, Duncan A.; Schroeder, Dustin M.

2014-10-01

202

An ALOS-derived glacier inventory of the Bhutan Himalaya  

NASA Astrophysics Data System (ADS)

Glacier inventory provides fundamental information of glacier settings such as number, area, and horizontal/altitudinal distribution, which make possible to study management of water resources, glacial response to climate change, and glacier-related hazards. In the Bhutan Himalaya, heavily debris-covered surface and seasonal snow cover under the humid climate hamper automated mapping of glaciers. We present a novel glacier inventory manually delineated from high resolution (2.5 m) ALOS-PRISM images along the Bhutan Himalaya including Tibetan side. We delineated 1273 glaciers with area of 1408.3 km2, in which 210 debris-covered glaciers with area of 951.2 km2 were identified. Scatter plot of top and terminus altitudes of these glaciers shows that the termini of debris-covered glaciers tend to be located at lower altitude than those of debris-free glaciers. Classifying surface aspect into eight directions, surface of the debris-free glaciers tends to be exposed northward (16.7%) while the southwestward surface is minimum (9.2%). No remarkable aspect tendency is found for the debris-covered glaciers. We compare the locations of debris-free glaciers with annual precipitation of TRMM 3B43 data. Median altitude, at which glacier surface is divided into two equal areas obviously increases northward (toward Tibet) along latitude. Additionally the median altitude averaged over basin scale (~2500 km2) shows a significant negative correlation against the annual precipitation (r= -0.48, p< 0.05). Our results suggest that the high latitudinal gradient of annual precipitation crossing the Bhutan Himalaya contrasts the glacier altitudinal distribution within a scale of 100 km.

Nagai, Hiroto; Fujita, Koji; Nuimura, Takayuki; Sakai, Akiko

2013-04-01

203

Glacier area and length changes in Norway from repeat inventories  

NASA Astrophysics Data System (ADS)

In this study, we assess glacier area and length changes in mainland Norway from repeat Landsat TM/ETM+ derived inventories and digitized topographic maps. The multi-temporal glacier inventory consists of glacier outlines from within three time ranges: 1947 to 1985 (GIn50), 1988 to 1997 (GI1990), and 1999 to 2006 (GI2000). For the northernmost regions, we include an additional inventory (GI1900), based on historic maps surveyed between 1895 to 1907. Area and length changes are assessed per glacier unit, for 36 subregions, and for three main parts of Norway: southern, central and northern Norway. The results show a decrease of the glacierized area from 2994 km2 in GIn50, to 2668 km2 in GI2000 (totally 2722 glacier units), corresponding to an area reduction of -326 km2, or -11% of the initial GIn50 area. This is equivalent to an average change rate of -11 km2 a-1 over the past 30 years. The average length change for the full epoch (within GIn50 and GI2000) is -240 m, corresponding to an average length change rate of -8 m a-1. Overall, the comparison reveals both area and length reduction as a general pattern, even though some glaciers have advanced. The three northernmost glacier regions show the strongest retreat rates, whereas the central part of Norway shows the lowest change rates. Glacier area and length changes indicate that glaciers in maritime areas in southern Norway have retreated more than glaciers in the interior, and glaciers in the north have retreated more than southern glaciers. These observed spatial trends in glacier change are related to a combination of several geographical factors like glacier geometry and elevation, and other climatic aspects, such as continentality and the North Atlantic Oscillation.

Winsvold, S. H.; Andreassen, L. M.; Kienholz, C.

2014-06-01

204

Contrasting response of South Greenland glaciers to recent climatic change  

SciTech Connect

A unique geographical configuration of glaciers exists in the Narsarsuaq district of South Greenland. Two large outlet glaciers divide into seven distributaries, such that each glacier system has land-terminating, tidewater-calving, and fresh-water-calving termini. Despite a similar climatic regime, these seven glaciers have exhibited strongly contrasting terminal behavior in historical time, as shown by historical records, aerial photographs, and fieldwork in 1989. The behavior of the calving glaciers cannot be accounted for with reference solely to climatic parameters. The combination of iceberg calving dynamics and topographic control has partially decoupled them from climatic forcing such that their oscillations relate more closely to glaciodynamic than glacioclimatic factors.

Warren, C.R.; Glasser, N.F. (Univ. of Edinburgh, Scotland (United Kingdom))

1992-05-01

205

Prairies in the Prairie State : How Glaciers Shape the Land  

NSDL National Science Digital Library

This hands-on activity demonstrates the abrasive power of glaciers carrying rocks and sand. Its purpose is to illustrate the concept that glaciers change the Earth's surface through the processes of erosion and deposition. Students construct model glaciers by freezing water with sand and pebbles at the bottom to represent the rock fragments carried by a real glacier. They then rub their 'glacier' across rocks of varying hardness to see what happens. Afterwards, they place the ice where it can melt and observe what happens to the sand and pebbles trapped in it. A materials list, procedures, and background information are supplied.

206

Surface change detection in glacier regions using ALOS PALSAR data  

NASA Astrophysics Data System (ADS)

Mountainous glaciers are important water resources in the high mountainous region. The glaciers not only supply water for drinking and agriculture, but also produce energy in hydroelectric power plants to local communities. The recent rapid glacier retreat is at high risk for severe water shortage in the near future. And the melting water of glacier sometimes leads to landslide disaster or glacier lake outburst flood (GLOF). Actually, the debris flow happened and damaged the buildings at the valley of Pacuni glacier in Bolivia in December 2007. Consequently, the monitoring of the glacier regions is very important both to manage water resources and to mitigate the damage from landslide disaster. The Advanced Land Observing Satellite DAICHI (ALOS) has three sensors, two visible imagers and one L-band polarimetric SAR, and has been observing the land surface since 2006. This study discusses the availability of the Phased-Array type L-band Synthetic Aperture Radar (PALSAR) of ALOS for surface change detection in glacier regions in Bolivia. The observation by PALSAR is unaffected by weather. And this characteristic is the most important for the glacier monitoring. Some glaciers and their surrounding mountainous regions are selected as a test sites for this study and many landslides near Pacuni glacier were detected by Differential Interferometric SAR (DInSAR) technique using PALSAR data of ALOS.

Tomiyama, N.; Ono, M.

2010-12-01

207

Monitoring surging glaciers of the Pamirs, central Asia, from space  

NASA Astrophysics Data System (ADS)

The evolution of surging glaciers of the Pamirs, central Asia, has been studied using repeat remote-sensing surveys in the Institute of Geography, Russian Academy of Sciences, since the early 1970s. We use images obtained from national Resurs-F satellites (1972-91), as well as Landsat 7 and Terra (1999-2006), to provide a basis for monitoring of surging glaciers, aimed at developing their inventory, studying the causes and mechanisms of surges and examining the timing and extent of glacial catastrophes. The inventory from the early 1990s allows identification of 215 glaciers with a dynamically unstable regime. We discovered 51 surging glaciers. Up until 2006, 10 more surges had occurred. We use stereoscopic deciphering and photogrammetric processing of consecutive satellite images to study the morphology and ice-velocity changes of several compound surging glaciers. We analyze the results of monitoring of Bivachny and Oktyabr'sky glaciers from 1972 to 1991 and Sugran glacier from 1972 to 2006. Two surges of Sugran glacier occurred during this time: an internal surge in 1976-80, and a surge with glacier tongue advance as far as 4.5 km in 2000-05. The role of damming in compound glacier systems is examined. Satellite-based monitoring is now the only method for obtaining initial information about the state and fluctuations of such glaciers.

Kotlyakov, V. M.; Osipova, G. B.; Tsvetkov, D. G.

208

A complex relationship between calving glaciers and climate  

USGS Publications Warehouse

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

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

2011-01-01

209

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

SciTech Connect

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

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

1985-01-01

210

SAR investigations of glaciers in northwestern North America  

NASA Technical Reports Server (NTRS)

The objective of this project was to investigate the utility of satellite synthetic aperture radar (SAR) imagery for measurement of geophysical parameters on Alaskan glaciers relevant to their mass balance and dynamics, including: (1) the positions of firn lines (late-summer snow lines); (2) surface velocities on fast-flowing (surging) glaciers, and also on slower steady-flow glaciers; and (3) the positions and changes in the positions of glacier termini. Preliminary studies of topography and glacier surface velocity with SAR interferometry have also been carried out. This project was motivated by the relationships of multi-year to decadal changes in glacier geometry to changing climate, and the probable significant contribution of Alaskan glaciers to rising sea level.

Lingle, Craig S.; Harrison, William D.

1995-01-01

211

Glaciers and Ice Sheets Mapping Orbiter concept  

Microsoft Academic Search

We describe a concept for a spaceborne radar system designed to measure the surface and basal topography of terrestrial ice sheets and to determine the physical properties of the glacier bed. Our primary objective is to develop this new technology for obtaining spaceborne estimates of the thickness of the polar ice sheets with an ultimate goal of providing essential information

Kenneth Jezek; Ernesto Rodrguez; Prasad Gogineni; Anthony Freeman; John Curlander; Xiaoqing Wu; John Paden; Chris Allen

2006-01-01

212

Stream temperature response to glacier retreat (Invited)  

NASA Astrophysics Data System (ADS)

Stream temperature is a fundamental aspect of aquatic habitat, and there has been increasing concern in recent years that climatic change and glacier retreat will result in increased water temperatures, with potentially negative influences on cold and cool water species such as salmonids. A statistical model was developed to predict the maximum weekly average stream temperature based on data from 418 sites located throughout British Columbia, Canada. Catchment-scale glacier coverage was a significant predictor in the model, and example calculations indicate that plausible decreases in glacier coverage over the next few decades have the potential to result in warming that would be sufficient to cause shifts in fish species assemblages. However, this space-for-time substitution rests on assumptions that may not be valid, especially in the context of a changing climate, leading to a need to develop and apply physically based models. Reach-scale energy budget analyses indicate that parameterizations of energy fluxes used in current stream temperature models are not appropriate for steep channels with cascading flow. In particular, the sensible and latent heat fluxes are more efficient than in lower-gradient channels, and the albedo is enhanced by aeration. Over longer time scales, development of riparian forest has the potential to mitigate the effect of glacier retreat in alpine areas by shading the stream, but it may take centuries for functional riparian forest to develop at higher elevation sites.

Moore, R. D.

2013-12-01

213

Hasty retreat of glaciers in the Palena province of Chile  

NASA Astrophysics Data System (ADS)

Mapping glacier extent from optical satellite data has become a most efficient tool to create or update glacier inventories and determine glacier changes over time. A most valuable archive in this regard is the nearly 30-year time series of Landsat Thematic Mapper (TM) data that is freely available (already orthorectified) for most regions in the world from the USGS. One region with a most dramatic glacier shrinkage and a missing systematic assessment of changes, is the Palena province in Chile, south of Puerto Montt. A major bottleneck for accurate determination of glacier changes in this region is related to the huge amounts of snow falling in this very maritime region, hiding the perimeter of glaciers throughout the year. Consequently, we found only three years with Landsat scenes that can be used to map glacier extent through time. We here present the results of a glacier change analysis from six Landsat scenes (path-rows 232-89/90) acquired in 1985, 2000 and 2011 covering the Palena district in Chile. Clean glacier ice was mapped automatically with a standard technique (TM3/TM band ratio) and manual editing was applied to remove wrongly classified lakes and to add debris-covered glacier parts. The digital elevation model (DEM) from SRTM was used to derive drainage divides, determine glacier specific topographic parameters, and analyse the area changes in regard to topography. The scene from 2000 has the best snow conditions and was used to eliminate seasonal snow in the other two scenes by digital combination of the binary glacier masks. The observed changes show a huge spatial variability with a strong dependence on elevation and glacier hypsometry. While small mountain glaciers at high elevations and steep slopes show virtually no change over the 26-year period, ice at low elevations from large valley glaciers shows a dramatic decline (area and thickness loss). Some glaciers retreated more than 3 km over this time period or even disappeared completely. Typically, these glaciers lost contact to the accumulation areas of tributaries and now consist of an ablation area only. Furthermore, numerous pro-glacial lakes formed or expanded rapidly, increasing the local hazard potential. On the other hand, some glaciers located on or near to (still active) volcanoes have also advanced in the same time period. Observed trends in temperature (decreasing) are in contrast to the observed strong glacier shrinkage.

Paul, F.; Mlg, N.; Bolch, T.

2013-12-01

214

Changes in the Surface Area of Glaciers in Northern Eurasia  

NASA Astrophysics Data System (ADS)

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

Khromova, T.; Nosenko, G.

2012-12-01

215

Meltwater Induced Glacier Landslides - Waxell Ridge, AK  

NASA Astrophysics Data System (ADS)

Within the past year, two large landslides have originated from south-facing peaks on Waxell Ridge, the bedrock massif that separates the Bagley Icefield from Bering Glacier, Alaska. Each involves a near-summit hanging glacier. In each instance, the presence of meltwater appears to be a triggering factor. The largest of the two, which occurred on September 14, 2005, originated from just below the summit of 3,236-m-high Mt Steller and landed on the surface of Bering Glacier, nearly 2,500 m below. The Alaska Volcano Observatory estimated the volume of this landslide, which consisted of rock, glacier ice, and snow, to be approximately 50 million cubic meters. Unlike most large Alaskan glacier-related landslides, this one was not triggered by an earthquake. However, the energy that the slide released was intense enough to generate a seismic signal that was recorded around the world with magnitudes of 3.8 to greater than 5. The slide extended ~10 km down the Bering Glacier from the point of impact. Much of the surface on which the slide occurred had a slope >50 degrees. The second landslide, located ~6 km to the west of Mt Steller, originated from a secondary summit of a 2,500- m-high unnamed peak. The date of its occurrence is unknown, but its toe sits on winter 2005-2006 snow. Both slides have been examined from helicopter and fixed-wing overflights, and with a variety of vertical and oblique aerial photographs. Oblique aerial photographs obtained of the Mt Steller slide on September 15, 2005 depict a 10-15-m-diameter moulin or englacial stream channel in the truncated 30-m-thick glacier ice that comprises the east wall of the landslide scarp. The presence of this unusual glacial-hydrologic feature at an elevation above 3,000 m, suggests that a large volume of water had recently been flowing on Mt Steller's east ridge and that the water might have had a role in triggering the landslide. Similarly, there is evidence of an englacial channel on the west flank of the summit scarp of the second slide. The presence of large volumes of meltwater close to the crest of Waxell Ridge raises questions about regional climate change and its role in the future generation of landslides at higher elevations. This presentation summarizes the findings produced from the analysis of aerial photography and field observations made between September 2005 and September 2006.

Molnia, B. F.; Angeli, K. M.; Bratton, D. A.; Keeler, R. H.; Noyles, C.

2006-12-01

216

Surge of a Complex Glacier System - The Current Surge of the Bering-Bagley Glacier System, Alaska  

NASA Astrophysics Data System (ADS)

Understanding fast glacier flow and glacial accelerations is important for understanding changes in the cryosphere and ultimately in sea level. Surge-type glaciers are one of four types of fast-flowing glaciers --- the other three being continuously fast-flowing glaciers, fjord glaciers and ice streams --- and the one that has seen the least amount of research. The Bering-Bagley Glacier System, Alaska, the largest glacier system in North America, surged in 2011 and 2012. Velocities decreased towards the end of 2011, while the surge kinematics continued to expand. A new surge phase started in summer and fall 2012. In this paper, we report results from airborne observations collected in September 2011, June/July and September/October 2012 and in 2013. Airborne observations include simultaneously collected laser altimeter data, videographic data, GPS data and photographic data and are complemented by satellite data analysis. Methods range from classic interpretation of imagery to analysis and classification of laser altimeter data and connectionist (neural-net) geostatistical classification of concurrent airborne imagery. Results focus on the characteristics of surge progression in a large and complex glacier system (as opposed to a small glacier with relatively simple geometry). We evaluate changes in surface elevations including mass transfer and sudden drawdowns, crevasse types, accelerations and changes in the supra-glacial and englacial hydrologic system. Supraglacial water in Bering Glacier during Surge, July 2012 Airborne laser altimeter profile across major rift in central Bering Glacier, Sept 2011

Herzfeld, U. C.; McDonald, B.; Trantow, T.; Hale, G.; Stachura, M.; Weltman, A.; Sears, T.

2013-12-01

217

Conditions for thrust faulting in a glacier  

NASA Astrophysics Data System (ADS)

Dipping, arcuate bands of debris-rich ice outcropping near the margins of glaciers are often interpreted as thrust faults, assumed to originate in zones of longitudinal compression. Identification of thrusts is typically based either on the geometry and sedimentology of the debris bands or on the crystal fabric of surrounding ice, but the physical processes necessary to generate thrusts are rarely evaluated. Herein, we combine a numerical model of compressive ice flow near a glacier margin with theoretical stress and strain rate criteria for ice fracture and stress criteria for frictional slip to determine the conditions necessary for thrust faulting in glaciers. This model is applied to two different glaciological settings where longitudinal compression has been documented: (1) the transition between warm-based and cold-based ice near the terminus of Storglaciren, Sweden, and (2) the downglacier extent of the 1983 surge front of Variegated Glacier where surging ice encountered stagnant ice. Simulations representing the margin of Storglaciren indicate that peak compressive strain rates are six orders of magnitude too small to induce fracture, whereas at Variegated Glacier, strain rates were an order of magnitude too small for compressive fracture. In both groups of simulations, preexisting fractures governed by Coulomb friction are susceptible to slip if they span the ice thickness, are oriented close to the optimal fracture angle, and, in the case of Storglaciren, are subject to water pressures that are a large fraction of ice overburden pressure. Variations about the optimal fracture orientation, low or zero water pressure, high sliding friction coefficient, and limited vertical or lateral fracture extent each tend to suppress thrusting.

Moore, Peter L.; Iverson, Neal R.; Cohen, Denis

2010-06-01

218

A glacier inventory for the western Nyainqentanglha Range and the Nam Co Basin, Tibet, and glacier changes 1976-2009  

NASA Astrophysics Data System (ADS)

The western Nyainqentanglha Range is located in the south-eastern centre of the Tibetan Plateau. Its north-western slopes drain into Lake Nam Co. The region is of special interest for glacio-climatological research as it is influenced by both the continental climate of Central Asia and the Indian Monsoon system, and situated at the transition zone between temperate and subcontinental glaciers. A glacier inventory for the whole mountain range was generated for the year around 2001 using automated remote sensing and GIS techniques based on Landsat ETM+ and SRTM3 DEM data. Glacier change analysis was based on data from Hexagon KH-9 and Landsat MSS (both 1976), Metric Camera (1984), and Landsat TM/ETM+ (1991, 2001, 2005, 2009). Manual adjustment was especially necessary for delineating the debris-covered glaciers and the glaciers on the panchromatic Hexagon data. In the years around 2001 the whole mountain range contained about 960 glaciers covering an area of 795.6 22.3 km2 while the ice in the drainage basin of Nam Co covered 198.1 5.6 km2. The median elevation of the glaciers was about 5800 m with the majority terminating around 5600 m. Five glaciers with debris-covered tongues terminated lower than 5200 m. The glacier area decreased by -6.1 3% between 1976 and 2001. This is less than reported in previous studies based on the 1970s topographic maps and Landsat data from 2000. Glaciers continued to shrink during the period 2001-2009. No advancing glaciers were detected. Detailed length measurements for five glaciers indicated a retreat of around 10 m per year (1976-2009). Ice cover is higher south-east of the mountain ridge which reflects the windward direction to the monsoon. The temperature increase during the ablation period was probably the main driver of glacier wastage, but the complex glacier-climate interactions need further investigation.

Bolch, T.; Yao, T.; Kang, S.; Buchroithner, M. F.; Scherer, D.; Maussion, F.; Huintjes, E.; Schneider, C.

2010-09-01

219

Glacier-and permafrost-related hazards increasingly threaten human lives,settlements,  

E-print Network

Glacier- and permafrost-related hazards increasingly threaten human lives where surface and sub-surface ice are involved.Changes in glacier and permafrost equilibrium in the Italian Alps. Glacier-related Hazards Glacier- and permafrost-related hazards include glacier lake

Kääb, Andreas

220

Franz Josef and Fox Glaciers, New Zealand: Historic length records  

NASA Astrophysics Data System (ADS)

Compilation of modern and historical length change records for Franz Josef and Fox Glaciers demonstrates that these glaciers have lost ~ 3 km in length and at least 3-4 km2 in area since the 1800s, with the greatest overall loss occurring between 1934 and 1983. Within this dramatic and ongoing retreat, both glaciers have experienced periods of re-advance. The record from Franz Josef Glacier is the most detailed, and shows major advances from 1946 to 1951 (340 m), 1965-1967 (400 m), 1983-1999 (1420 m) and 2004-2008 (280 m). At Fox Glacier the record is similar, with advances recorded during 1964-1968 (60 m), 1985-1999 (710 m) and 2004-2008 (290 m). Apart from the latest advance event, the magnitude of advance has been greater at Franz Josef Glacier, suggesting a higher length sensitivity. Analysis of the relationship between glacier length and a reconstructed annual equilibrium line altitude (ELA) record shows that the glaciers react very quickly to ELA variations - with the greatest correlation at 3-4 years' lag. The present (2014) retreat is the fastest retreat in the records of both glaciers. While decadal length fluctuations have been linked to hemispheric ocean-atmosphere variability, the overall reduction in length is a clear sign of twentieth century warming. However, documenting glacier length changes can be challenging; especially when increased surface debris-cover makes identification of the true terminus a convoluted process.

Purdie, Heather; Anderson, Brian; Chinn, Trevor; Owens, Ian; Mackintosh, Andrew; Lawson, Wendy

2014-10-01

221

Rock glaciers in the South Shetland Islands, Western Antarctica  

NASA Astrophysics Data System (ADS)

Rock glaciers are found in the peripheral regions of Antarctica particularly in the Antarctic Peninsula region. Study of these features is relevant for the palaeoenvironmental reconstruction of maritime Antarctica because they are indicators of permafrost and periglacial conditions. This paper reports and analyzes the results of an inventory of rock glaciers and protalus lobes in the South Shetland Islands. Nine rock glaciers and eleven protalus lobes have been identified. All of them are located in recently deglaciated zones between 300 m a.s.l. and sea level and they cover an area of 497103 m 2. Tongue-shaped rock glaciers are more common than lobate types, being in general of medium and small sizes. They are talus rock glaciers (55%) and debris rock glaciers (45%), according to the genetic classification. The lack of a preferred orientation suggests that there is no significant microclimate control on their distribution. They are related to particular morphodynamic situations. Estimated annual velocities, based on relationships with raised beaches and transported debris volumes, range between 2.4 and 97 cm year -1, within the ranges reported for other rock glaciers. Three groups of rock glaciers can be recognised: (a) those immediate postdating the last major ice recession, (b) rock glaciers younger than 2000 years BP but pre-dating the Little Ice Age (LIA), and (c) rock glaciers formed during the LIA.

Serrano, Enrique; Lpez-Martnez, Jernimo

2000-10-01

222

Glacier Changes in the Bhutanese Himalaya - Present and Future  

NASA Astrophysics Data System (ADS)

Glacierized change in the Himalayas affects river-discharge, hydro-energy and agricultural production, and Glacial Lake Outburst Flood potential, but its quantification and extent of impacts remains highly uncertain. Here we present conservative, comprehensive and quantitative predictions for glacier area and meltwater flux changes in Bhutan, monsoonal Himalayas. In particular, we quantify the uncertainties associated with the glacier area and meltwater flux changes due to uncertainty in climate data, a critical problem for much of High Asia. Based on a suite of gridded climate data and a robust glacier melt model, our results show that glacier area and meltwater change projections can vary by an order of magnitude for different climate datasets. The most conservative results indicate that, even if climate were to remain at the present-day mean values (1980-2000), almost 10% of Bhutan's glacierized area would vanish and the meltwater flux would drop by as much as 30%. New mapping of glacierized area from 2000-2010 shows a significant change in glacierized area of 4-6%. Thus the conservative steady-state area changes predicted by the model are already being realized. Under the conservative scenario of an additional 1C regional warming, glacier retreat is predicted to continue until about 25% of Bhutan's glacierized area will have disappeared and the annual meltwater flux, after an initial spike, would drop by as much as 65%.

Rupper, S.; Schaefer, J. M.; Burgener, L. K.; Maurer, J.; Smith, R.; Cook, E.; Putnam, A. E.; Krusic, P.; Tsering, K.; Koenig, L.

2012-12-01

223

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

224

Modelling glacier change in the Everest region, Nepal Himalaya  

NASA Astrophysics Data System (ADS)

In this study, we apply a glacier mass balance and ice redistribution model to simulate historical and future glacier change in the Everest region of Nepal. High-resolution temperature and precipitation fields derived from gridded APHRODITE data, and validated against independent station observations from the EVK2CNR network, are used to drive the historical model from 1961 to 2007. The model is calibrated against geodetically derived estimates of net glacier mass change from 1992 to 2008, termini position of four large glaciers at the end of the calibration period, average velocities observed on selected debris-covered glaciers, and total glacierized area. We integrate field-based observations of glacier mass balance and ice thickness with remotely-sensed observations of decadal glacier change to validate the model. Between 1961 and 2007, the mean modelled volume change over the Dudh Kosi basin is -6.4 1.5 km3, a decrease of 15.6% from the original estimated ice volume in 1961. Modelled glacier area change between 1961 and 2007 is -101.0 11.4 km2, a decrease of approximately 20% from the initial extent. Scenarios of future climate change, based on CMIP5 RCP4.5 and RCP8.5 end members, suggest that glaciers in the Everest region will continue to lose mass through the 21st century. Glaciers in the basin are concentrated between 5000 and 6000 m of elevation, and are thus expected to be sensitive to changes in temperature and equilibrium line altitude (ELA). Glacier volume reductions between -35 to -62% are possible by 2050, and sustained temperature increases to 2100 may result in total glacier volume losses of between -73 and -96%.

Shea, J. M.; Immerzeel, W. W.; Wagnon, P.; Vincent, C.; Bajracharya, S.

2014-10-01

225

When glaciers were carried away with themselves: Iceland's cataclysmic jokulhlaups  

NASA Astrophysics Data System (ADS)

Unprecedented scenes of floodwater bursting from Skeidararjokull, Iceland in 1996 have prompted a revised understanding of dynamic glacier response to sudden, massive influxes of floodwater. Using evidence from the 1996 jokulhlaup, we present an overview of glacier response and jokulhlaup characteristics resulting from igneous activity beneath the Myrdalsjokull and Orfajokull ice caps, Iceland. The need to improve understanding of cataclysmic jokulhlaup processes is motivated by findings from recent geophysical surveys at Myrdalsjokull, which reveal that magma is accumulating at depth beneath the ice cap. Specifically, we seek to explain: (i) glaciohydraulic processes responsible for rapid, unstable floodwater release; (ii) consequent sub-glacier hydrodynamics; (iii) glacier response to the kinematic movement of basal floodwater; (iv) the propensity for intraglacial floodwater routing; (v) hydromechanical processes at the glacier terminus; and (vi) resulting ice-proximal to ice-distal sedimentary and glacier ice deposits. Glaciological and sedimentological evidence is presented from jokulhlaups that accompanied volcanic eruptions beneath Myrdalsjokull in 1721 and 1918, and Oraefajokull in 1362 and 1727. In summary, phreato-magmatic eruptions within the ice-filled calderas of both ice caps caused tremendous ice-melt that generated hydraulic pressures much greater than glacier yield strength, thereby facilitating unstable cavity growth and localised glacier flotation. Imposition of negative effective-pressure inhibited the formation of classical tunnelled drainage, despite ice-melt-widening effects due to thermal advection. Instead, floodwater moved swiftly both down-glacier and laterally as an unregulated kinematic wave. The hydrodynamic effects of this wave caused supraglacial outbursts of basal floodwater, widespread upheaval of the glacier surface and attendant ice shearing, and enhanced (albeit localised) glacier sliding. Massive sections of glacier ice were fractured and incorporated simultaneously in flows laden with juvenile eruptives, which on reaching the North Atlantic, perpetuated as hyperpycnal flows. Glacier ice removed during these jokulhlaups lay stranded in ice-proximal locations for up to 200 years.

Roberts, M. J.; Bjornsson, H.; Russell, A. J.; Tweed, F. S.; Stefansson, R.; Knudsen, O.

2003-04-01

226

The GLIMS Glacier Database: Status and Future Directions  

NASA Astrophysics Data System (ADS)

The Global Land Ice Measurements from Space (GLIMS) initiative has built a database of glacier outlines and related attributes, derived primarily from satellite imagery, such as from ASTER and Landsat. Each snapshot of a glacier is from a specific time, and the database is designed to store multiple snapshots representative of different times. The database continues to expand both spatially and temporally: the number of glaciers represented, as well as the number of outlines from different times per glacier, are both increasing. As of August 2011, the database, located at NSIDC, contains outlines for approximately 95 000 glaciers, covering 290 000 km2. More datasets are expected soon, such as from GlobGlacier (e.g. all European Alps, western Greenland, Sweden, Baffin Island), and the Regional Centers for Svalbard, Argentina, Nepal, China, and others. Though the database does not yet cover the world's glaciers completely, approximately 670 glaciers have outlines from more than one time. This database increasingly enables analysis of global and regional glacier area and its distribution, glacier change, distribution of glaciers by different properties (e.g. morphology, debris-cover),and other yet-to-be imagined possibilities. In spite of steady progress, there remain some geographic areas that are not yet covered, including southernmost South America, Arctic Russia, the the periphery of most of Greenland and Antarctica. For applications such as sea level change studies that require complete global coverage of glaciers with at least moderate resolution, it is imperative that these gaps be filled soon. This will be addressed through adapting existing datasets to the GLIMS data model, using new satellite data and methods as they develop, and building analysis capacity worldwide to get more researchers involved in high accuracy glacier mapping.

Armstrong, R. L.; Racoviteanu, A.; Raup, B. H.; Khalsa, S. S.

2011-12-01

227

Recent Changes in Canada's Arctic Glaciers  

NASA Astrophysics Data System (ADS)

Canada's Arctic islands contain over 110,000 km2 of ice caps and glaciers, the largest area of land ice in the world outside Antarctica and Greenland. This region is projected to experience summer warming of 1-4C over the next century due to the build-up of greenhouse gases in the atmosphere. The small ice masses in this region are likely to respond more rapidly to this warming than the larger Greenland ice sheet, and they may contribute appreciably to sea level changes over the next century. Glacier mass balance in the region has been persistently negative over the past 40 years. On Devon ice cap, the mass balance of the accumulation zone has become progressively more positive over that period, while that of the ablation zone has become progressively more negative. This suggests that the hydrological cycle in this part of the Arctic has become more vigorous over time. Balance fluxes computed for Devon ice cap were compared with observed fluxes (determined from ice thickness and surface velocity measurements derived from airborne radio echo sounding and SAR interferometry respectively). This comparison suggests that, over most of the ice cap, accumulation areas are thickening at rates of up to 0.15 m a-1, while ablation areas are thinning at rates of up to 0.8 m a-1. The exception is the southeast sector of the ice cap where accumulation areas appear to be thinning at up to 0.3 m a-1. Since 1960, the extent of land ice cover in the Arctic islands has decreased by around 1.8%. Rates of change are largest along the northern and southern coastal fringes of the Arctic Archipelago and lowest in interior regions. The margins of larger ice caps and glaciers terminating on land show little change. Small ice caps and tidewater-terminating outlet glaciers are most strongly affected. This suggests that iceberg calving may have contributed significantly to mass loss in some regions. For Devon ice cap, the calving contribution may be as large as 35%. Volume-area scaling techniques have been used to make a preliminary estimate of the ice volume loss associated with the reduction in ice-covered area. The potential contribution to global sea level is on the order of 1.5mm for the period 1960-2000. A significant number of glaciers show evidence of changes in flow regime, and such changes have resulted in both advances and retreats of glacier margins. Whether these flow regime changes represent normal surge-type behaviour or a response to climate forcing is not yet clear.

Sharp, M.; Burgess, D. O.; Copland, L.; Filbert, K.; Williamson, S.

2004-05-01

228

Remote Sensing Applications for the Bering Glacier, Alaska  

NASA Astrophysics Data System (ADS)

Satellite remote sensing is an invaluable tool to monitor and characterize the Bering Glacier System. The Bering Glacier is located in coastal, south-central Alaska and 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 great surge occurred in 1993- 1995. Bering Glacier alone covers more than 6 percent of the glacier covered area of Alaska and may contain 15- 20 percent of Alaska's total glacier ice. Applications of glacier remote sensing include but are not limited to: mapping extent and features, ice velocities through sequential observations, glacier terminus locations, snow line location, glacier albedo, changes in glacier volume, iceberg surveys and calving rates, hydrographic and water quality parameters in ice marginal lakes, and land cover classification maps. Historical remote sensing images provide a much needed geospatial time record of the dynamic changes Bering Glacier has undergone, including changes due to its surge behavior and response to climate change. Remote sensing images dating back to the early 1990s have been used to map the glacier terminus retreat of approximately five to seven kilometers which has resulted in Vitus Lake increasing in volume approximately 260 percent since 1995 to the current (2006) volume of 9.4 km3 of water. Using elevation data obtained from remote sensing and GPS surface points, we have determined that the glacier elevation has decreased approximately 150 m in elevation at the terminus and 30 m at a position 300 m below the present (2006) equilibrium line (~1,300 m) since 1972. Satellite observations have recorded the upward migration in altitude of the equilibrium line to its present position (slightly > 1,200 m). The decrease in glacier volume, obtained using remote sensing derived elevation data, from 1957 to 2004 is estimated at approximately 104 km3. Remote sensing data has also mapped the sediment rich (rock flower) water flowing into Vitus Lake providing insight into the hydrologic circulation of the Bering Glacier system, showing major glacier discharge from the Abandoned River, Arrowhead Point, and Lamire Bay in the area of Vitus Lake west of Taggland.

Liversedge, L.; Shuchman, R.; Josberger, E.; Payne, J.; Hatt, C.; Spaete, L.

2007-12-01

229

A metagenomic snapshot of taxonomic and functional diversity in an alpine glacier cryoconite ecosystem  

NASA Astrophysics Data System (ADS)

Cryoconite is a microbe-mineral aggregate which darkens the ice surface of glaciers. Microbial process and marker gene PCR-dependent measurements reveal active and diverse cryoconite microbial communities on polar glaciers. Here, we provide the first report of a cryoconite metagenome and culture-independent study of alpine cryoconite microbial diversity. We assembled 1.2 Gbp of metagenomic DNA sequenced using an Illumina HiScanSQ from cryoconite holes across the ablation zone of Rotmoosferner in the Austrian Alps. The metagenome revealed a bacterially-dominated community, with Proteobacteria (62% of bacterial-assigned contigs) and Bacteroidetes (14%) considerably more abundant than Cyanobacteria (2.5%). Streptophyte DNA dominated the eukaryotic metagenome. Functional genes linked to N, Fe, S and P cycling illustrated an acquisitive trend and a nitrogen cycle based upon efficient ammonia recycling. A comparison of 32 metagenome datasets revealed a similarity in functional profiles between the cryoconite and metagenomes characterized from other cold microbe-mineral aggregates. Overall, the metagenomic snapshot reveals the cryoconite ecosystem of this alpine glacier as dependent on scavenging carbon and nutrients from allochthonous sources, in particular mosses transported by wind from ice-marginal habitats, consistent with net heterotrophy indicated by productivity measurements. A transition from singular snapshots of cryoconite metagenomes to comparative analyses is advocated.

Edwards, Arwyn; Pachebat, Justin A.; Swain, Martin; Hegarty, Matt; Hodson, Andrew J.; Irvine-Fynn, Tristram D. L.; Rassner, Sara M. E.; Sattler, Birgit

2013-09-01

230

Snow glacier melt estimation in tropical Andean glaciers using artificial neural networks  

NASA Astrophysics Data System (ADS)

Snow and glacier melt (SGM) estimation plays an important role in water resources management. Although melting process can be modelled by energy balance methods, such studies require detailed data, which is rarely available. Hence, new and simpler approaches are needed for SGM estimations. The present study aims at developing an artificial neural networks (ANN) based technique for estimating the energy available for melt (EAM) and SGM rates using available and easy to obtain data such as temperature, short-wave radiation and relative humidity. Several ANN and multiple linear regression models (MLR) were developed to represent the energy fluxes and estimate the EAM. The models were trained using measured data from the Zongo glacier located in the outer tropics and validated against measured data from the Antizana glacier located in the inner tropics. It was found that ANN models provide a better generalisation when applied to other data sets. The performance of the models was improved by including Antizana data into the training set, as it was proved to provide better results than other techniques like the use of a prior logarithmic transformation. The final model was validated against measured data from the Alpine glaciers Argentire and Saint-Sorlin. Then, the models were applied for the estimation of SGM at Condoriri glacier. The estimated SGM was compared with SGM estimated by an enhanced temperature method and proved to have the same behaviour considering temperature sensibility. Moreover, the ANN models have the advantage of direct application, while the temperature method requires calibration of empirical coefficients.

Moya Quiroga, V.; Mano, A.; Asaoka, Y.; Kure, S.; Udo, K.; Mendoza, J.

2013-04-01

231

An Analysis of Mass Balance of Chilean Glaciers  

NASA Astrophysics Data System (ADS)

Glaciers in Chile range from very small glacierets found on the isolated volcanoes of northern Chile to the 13,000 sq.km Southern Patagonian Ice Field. Regular monitoring of these glaciers is very important as they are considered as sensitive indicators of climate change. Millions of people's lives are dependent on these glaciers for fresh water and irrigation purpose. In this study, mass balances of several Chilean glaciers were estimated using Aster satellite images between 2007 and 2012. Highly accurate DEMs were created with supplementary information from IceSat data. The result indicated a negative mass balance for many glaciers indicating the need for further monitoring of glaciers in the Andes.

Ambinakudige, S.; Tetteh, L.

2013-12-01

232

A study of the atmospheric surface layer and roughness lengths on the high-altitude tropical Zongo glacier, Bolivia  

NASA Astrophysics Data System (ADS)

atmospheric surface layer of high-altitude tropical glaciers is inadequately understood, particularly concerning turbulent fluxes. Measurements have shown that sublimation reduces melt energy in the dry season, but the errors are large when a katabatic wind maximum occurs at a low height. This study analyzed wind and temperature vertical profiles measured by a 6 m mast in the ablation area of the tropical Zongo glacier (16S, 5060 m above sea level) in the dry seasons of 2005 and 2007. Surface roughness lengths for momentum and temperature were derived from least squares fits of hourly wind and temperature profile data. Measurement errors were explored, focusing on the poorly defined reference level for sensor heights. A katabatic wind maximum at heights between 2 and 3 m was regularly observed during low wind speed and strong inversion conditions, or about ~50%of the time, greatly reducing the surface layer depth. The glacier surface, experiencing melting conditions in the early afternoon and strong cooling at night, remained relatively smooth with z0 ~ 1 mm and zT ~ 0.1 mm. Sensible heat flux measured at ~1 m was not very sensitive to the zero reference level due to two opposite effects: when measurement heights increase, profile-derived roughness lengths increase but temperature and wind gradients decrease. The relation between zT/z0 and the roughness Reynolds number Re* roughly agrees with the surface renewal model. However, this is mostly due to self-correlation because of the shared variable z0 in zT/z0 and Re*, which prevents a sound experimental validation of the model.

Sicart, Jean Emmanuel; Litt, Maxime; Helgason, Warren; Tahar, Vanessa Ben; Chaperon, Thomas

2014-04-01

233

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

Code of Federal Regulations, 2011 CFR

... 2011-07-01 false What types of commercial fishing are authorized in Glacier Bay...Regulations-Glacier Bay National Park and Preserve Commercial Fishing 13.1132 What types of commercial fishing are authorized in Glacier...

2011-07-01

234

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

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false What types of commercial fishing are authorized in Glacier Bay...Regulations-Glacier Bay National Park and Preserve Commercial Fishing 13.1132 What types of commercial fishing are authorized in Glacier...

2013-07-01

235

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

Code of Federal Regulations, 2012 CFR

... 2012-07-01 false What types of commercial fishing are authorized in Glacier Bay...Regulations-Glacier Bay National Park and Preserve Commercial Fishing 13.1132 What types of commercial fishing are authorized in Glacier...

2012-07-01

236

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

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false What types of commercial fishing are authorized in Glacier Bay...Regulations-Glacier Bay National Park and Preserve Commercial Fishing 13.1132 What types of commercial fishing are authorized in Glacier...

2010-07-01

237

BASINWIDE SEDIMENTATION PROCESSES AT GLACIER-DAMMED ICEBERG LAKE, SOUTHCENTRAL ALASKA  

E-print Network

BASINWIDE SEDIMENTATION PROCESSES AT GLACIER-DAMMED ICEBERG LAKE, SOUTHCENTRAL 2012 BASINWIDE SEDIMENTATION PROCESSES AT GLACIER-DAMMED ICEBERG LAKE, SOUTHCENTRAL ALASKA by Katie E examining sedimentation rates and varve thickness at Iceberg Lake, a glacier-dammed proglacial lake

Loso, Michael G.

238

Basaltic micrometeorites from the Novaya Zemlya glacier  

NASA Astrophysics Data System (ADS)

A large number of micrometeorites (MMs) was recovered from glacier deposits located at the north-eastern passive margin of the Novaya Zemlya glacier sheet. Melted, scoriaceous, and unmelted micrometeorites (UMMs) are present. Unmelted micrometeorites are dominated mostly by chondritic matter, but also a few achondritic MMs are present. Here we report the discovery of four UMMs that, according to their texture, mineralogy, and chemistry, are identified as basaltic breccias. Mineral chemistry and Fe/Mn ratios of two basaltic micrometeorites indicate a possible relationship with eucrites and/or mesosiderites, whereas two others seem to have parents, which appear not to be present in our meteorite collections. The basaltic breccia UMMs constitute 0.5% of the total population of the Novaya Zemlya MM suite. This content should be lowered to 0.25% because the Novaya Zemlya MM collection appears to be biased with carbonaceous UMMs being underrepresented.

Badjukov, Dmitry D.; Brandsttter, Franz; Raitala, Jouko; Kurat, Gero

2010-09-01

239

Changing Lake Bathymetry with Deglaciation: The Mendenhall Glacier System  

Microsoft Academic Search

Ongoing rapid ice ablation and glacier thinning has continued the buoyancy-driven, large-scale calving events and ice terminus collapse of the Mendenhall Glacier. New bathymetric data collected from Mendenhall Lake between 2004 and 2008 reveal lake shallowing adjacent to the 2008 glacier terminus. Since 2000, the lake has expanded beyond its former 3.4 km2 footprint to 4.02 km2 and enlarged its

C. Connor; N. Korzen; E. Knuth; D. Sauer; M. Heavner

2008-01-01

240

Microbial Life beneath a High Arctic Glacier  

Microsoft Academic Search

The debris-rich basal ice layers of a high Arctic glacier were shown to contain metabolically diverse microbes that could be cultured oligotrophically at low temperatures (0.3 to 4C). These organisms included aerobic chemoheterotrophs and anaerobic nitrate reducers, sulfate reducers, and methanogens. Colonies purified from subglacial samples at 4C appeared to be predominantly psychrophilic. Aerobic chemoheterotrophs were metabolically active in unfrozen

MARK L. SKIDMORE; JULIA M. FOGHT; MARTIN J. SHARP

2000-01-01

241

A macroscopic approach to glacier dynamics  

USGS Publications Warehouse

A simple approach to glacier dynamics is explored in which there is postulated to be a relationship between area and volume with three parameters: the time for area to respond to changes in volume, a thickness scale, and an area characterizing the condition of the initial state. This approach gives a good fit to the measurements of cumulative balance and area on South Cascade Glacier from 1970-97; the area time-scale is roughly 8 years, the thickness scale about 123 m, and the 1970 area roughly 4% larger than required for adjustment with volume. Combining this relationship with a version of mass continuity expressed in terms of area and volume produces a theory of glacier area and volume response to climate in which another time constant, the volume time-scale, appears. Area and volume both respond like a damped spring and mass system. The damping of the South Cascade response is approximately critical, and the volume time-scale is roughly 48 years, six times the area time-scale. The critically damped spring and mass analogy reproduces the time dependence predicted by the more complicated traditional theory of Nye.

Harrison, W. D.; Raymond, C. F.; Echelmeyer, K. A.; Krimmel, R. M.

2003-01-01

242

GLACIER PEAK WILDERNESS STUDY AREA, WASHINGTON.  

USGS Publications Warehouse

Geologic, geochemical, gravity, aeromagnetic, and mine and prospect surveys were conducted to evaluate the mineral-resource potential of the Glacier Peak Wilderness study area and proposed additions in Washington. In the study area, six areas containing several base and precious metals have been identified that have substantiated mineral-resource potential, two of which are in areas recommended for wilderness addition. An additional 10 areas have probable mineral-resource potential. The most important demonstrated resource identified is the porphyry copper-molybdenum deposit at Glacier Peak mine near the center of the wilderness study area, where a deposit totaling 1. 9 billion tons of mineralized rock has been delineated by drilling. A possible geothermal potential exists on the east side of the Glacier Peak volcano, and a possible 24-million-cu-yd cinder resource is identified at the White Chuck Cinder Cone in the wilderness study area, but both are remote and no resources were identified. No other energy resource potential was identified in this study.

Church, S.E.; Stotelmeyer, R.B.

1984-01-01

243

Global Terrestrial Network for Glaciers: Databases and Web interfaces  

NASA Astrophysics Data System (ADS)

The Global Terrestrial Network for Glaciers (GTN-G) is an umbrella organization with links to the Global Climate Observing System (GCOS), Global Terrestrial Observing System (GTOS), and UNESCO (all organizations under the United Nations), for the curation of several glacier-related databases. It is composed of the World Glacier Monitoring Service (WGMS), the U.S. National Snow and Ice Data Center (NSIDC), and the Global Land Ice Measurements from Space (GLIMS) initiative. The glacier databases include the World Glacier Inventory (WGI), the GLIMS Glacier Database, the Glacier Photograph Collection at NSIDC, and the Fluctuations of Glaciers (FoG) and Mass Balance databases at WGMS. We are working toward increased interoperability between these related databases. For example, the Web interface to the GLIMS Glacier Database has also included queryable layers for the WGI and FoG databases since 2008. To improve this further, we have produced a new GTN-G web portal (http://www.gtn-g.org/), which includes a glacier metadata browsing application. This web application allows the browsing of the metadata behind the main GTN-G databases, as well as querying the metadata in order to get to the source, no matter which database holds the data in question. A new glacier inventory, called the Randolph Glacier Inventory 1.0, has recently been compiled. This compilation, which includes glacier outlines that do not have the attributes or IDs or links to other data like the GLIMS data do, was motivated by the tight deadline schedule of the sea level chapter of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). Now served from the GLIMS website (http://glims.org/), it is designed to serve that narrowly focused research goal in the near term, and in the longer term will be incorporated into the multi-temporal glacier database of GLIMS. For the required merging of large sets of glacier outlines and association of proper IDs that tie together outlines that pertain to the same glacier (perhaps at different points in time), we at NSIDC have written software to examine geospatial relationships between the sets of outlines and assign attributes and linkages accordingly.

Raup, B.; Armstrong, R.; Fetterer, F.; Gartner-Roer, I.; Haeberli, W.; Hoelzle, M.; Khalsa, S. J. S.; Nussbaumer, S.; Weaver, R.; Zemp, M.

2012-04-01

244

Inventory of Glaciers in the North Cascades, Washington  

USGS Publications Warehouse

Perennial bodies of ice in the North Cascades having areas of at least 0.1 km2 (square kilometer) are tabulated and classified. The inventory, a contribution to the International Hydrological Decade, includes 756 glaciers, covering 267 km2, about half of the glacier area in the United States south of Alaska. Listings include each glacier's location, drainage basin, area, length, orientation, altitude, and classification as to form, source, surface, nature of terminus, and activity. These glaciers contribute annually about 800 million cubic meters of water to streamflow in the State of Washington.

Post, Austin; Richardson, Don; Tangborn, Wendell V.; Rosselot, F. L.

1971-01-01

245

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

246

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

NASA Astrophysics Data System (ADS)

The response of glaciers to changing climate is explored with an atmosphere/glacier hierarchical modeling approach, in which global simulations are downscaled with an Arctic MM5 regional model which provides temperature and precipitation inputs to a glacier mass-balance model. The mass balances of Hubbard and Bering Glaciers, south-central Alaska, USA, are simulated for October 1994-September 2004. The comparisons of the mass-balance simulations using dynamically-downscaled vs observed temperature and precipitation data are in reasonably good agreement, when calibration is used to minimize systematic biases in the MM5 downscalings. The responses of the Hubbard (a large tidewater glacier) and Bering (a large surge-type glacier) mass balances to the future climate scenario CCSM3 A1B, a 'middle-of-the-road' future climate in which fossil and non-fossil fuels are assumed to be used in balance, are also investigated for the period October 2010-September 2018. Hubbard and Bering Glaciers are projected to have increased accumulation, particularly on the upper glaciers, and greater ablation, particularly on the lower glaciers. The annual net balance for the entire Bering Glacier is projected to be significantly more negative, on average (-2.0 m a-1 w.e., compared to -1.3 m a-1 w.e. during the hindcast), and for the entire Hubbard Glacier somewhat less positive (0.3 m a-1 w.e. compared to 0.4 m a-1 w.e. during the hindcast). The Hubbard Glacier mass balances include an estimated iceberg calving flux of 6.5 km3 a-1, which is assumed to remain constant.

Zhang, Jing; Bhatt, Uma S.; Tangborn, Wendell V.; Lingle, Craig S.

2007-10-01

247

Global response of glacier runoff to twenty-first century climate change  

NASA Astrophysics Data System (ADS)

hydrology of many important river systems in the world is influenced by the presence of glaciers in their upper reaches. We assess the global-scale response of glacier runoff to climate change, where glacier runoff is defined as all melt and rain water that runs off the glacierized area without refreezing. With an elevation-dependent glacier mass balance model, we project monthly glacier runoff for all mountain glaciers and ice caps outside Antarctica until 2100 using temperature and precipitation scenarios from 14 global climate models. We aggregate results for 18 glacierized regions. Despite continuous glacier net mass loss in all regions, trends in annual glacier runoff differ significantly among regions depending on the balance between increased glacier melt and reduction in glacier storage as glaciers shrink. While most regions show significant negative runoff trends, some regions exhibit steady increases in runoff (Canadian and Russian Arctic), or increases followed by decreases (Svalbard and Iceland). Annual glacier runoff is dominated by melt in most regions, but rain is a major contributor in the monsoon-affected regions of Asia and maritime regions such as New Zealand and Iceland. Annual net glacier mass loss dominates total glacier melt especially in some high-latitude regions, while seasonal melt is dominant in wetter climate regimes. Our results highlight the variety of glacier runoff responses to climate change and the need to include glacier net mass loss in assessments of future hydrological change.

Bliss, Andrew; Hock, Regine; Radi?, Valentina

2014-04-01

248

Climate Change and Glacier Retreat: Scientific Fact and Artistic Opportunity  

NASA Astrophysics Data System (ADS)

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

Fagre, D. B.

2008-12-01

249

Climatic Controls on the Distribution of Surging Glaciers  

NASA Astrophysics Data System (ADS)

Surge-type glaciers are scattered in a non-random fashion, gathered in clusters in some glaciated regions. One group of clusters forms an Arctic and Sub-Arctic 'crescent', spanning from Alaska-Yukon, through Arctic Canada, West and East Greenland, Iceland, Svalbard and Novaya Zemlya. Another cluster occurs in western High Asia, including the Karakoram Mountains. Although several studies have assessed the influence of environmental controls on surging, so far none has provided a satisfactory explanation for the geographical location of these clusters. The distribution of such glaciers undoubtedly holds the keys of a better understanding on the controls on surging behaviour. For this study, two glacier populations are considered. First, a global inventory of glacier surges has been compiled, based on published observations, field reports and remote sensing studies. This digital database is structured in three tables, respectively providing information on the location and geometry of each surge-type glacier, surge dates and magnitude, and methodology employed at the time of observation. This global dataset is compared to the population of "non-surge-type glaciers" based on the Randolph Glacier Inventory version 2.0 excluding the inventoried surging glaciers. In both populations, glaciers are classified depending on their geometry and thermal regime. Downscaled climatic datasets are used to identify climatic envelopes associated with clusters of surging glaciers. We identified which environments are most prone to be associated to glacier surging, and examined the influence of these parameters on the surge cycle duration and character. These results emphasize the importance of external controls on surging (as against individual surges), and promote the need to study this behaviour in the frame of an energy-balance budget.

Sevestre, H.; Benn, D.

2012-12-01

250

Glacial Change in the Wind River Range, Wyoming, USA  

NASA Astrophysics Data System (ADS)

The upper Green River Basin (GRB) [located in the upper Colorado River Basin] and the upper Wind-Bighorn River Basin (WBRB) [located in the upper Missouri-Mississippi River Basin] are separated by the Wind River Range (WRR) of Wyoming. The WRR is an unbroken 160-kilometer barrier in west central Wyoming that is host to 63 glaciers, the largest concentration of glaciers in the American Rocky Mountains. These glaciers serve as natural water reservoirs and the continued recession of glaciers will impact agricultural water supply in the region. Previous research determined that the glaciers in the WRR contribute approximately 30% of the total streamflow volume during the critical late summer / early fall growing season. However, the previous research was limited in scope to a small number of climatic stations and limited streamflow measurements. The proposed research improves on previous research by evaluating glacial recession in the WRR using remote sensing techniques. Glacier area and terminus position for 42 glacial complexes in the WRR (from 1985 to present) will be evaluated using LANDSAT Imagery and GIS techniques. Next, for selected glaciers, aerial photograph stereopairs will also be obtained from the USGS Earth Resources, Observation and Science (EROS) Data Center in Sioux Falls, South Dakota from 1966 to present. The stereopair images will be utilized to derive the surface elevation of glaciers and calculate volume change. Traditional methods require the user to view the two photos with a stereoscope to view an object in three dimensions. Modern techniques allow this process to be completed digitally. Leica Photogrammetry suite is used to specify the spatial coordinates of each photo and create a block file, a file that consists of two or more photographs of the same area that contain spatial coordinates of each photo. Once the block file is created, the user can view the objects contained in the overlapping portions of the photos and make vertical measurements. This process allows the user to calculate changes in surface area and changes in elevation, thus volume changes can be computed. Glacier volume will also be estimated from glacier surface areas using the Bahr et al. (1997) area-volume scaling method. Finally, field data (real-time differential GPS surface survey, ground penetrating radar of ice thickness and repeat photography) from a summer 2006 site visit to Dinwoody Glacier (located on the east slope of the WRR) will be compared to previous site visits in the past 40 years. The field data will either confirm or reject observations from the remote sensing approach.

Cheesbrough, K.; Edmunds, J.; Kerr, G.; Pochop, L.; Tootle, G.

2007-12-01

251

Monitoring Tidewater Glacier Processes Using A Long-Range Terrestrial LiDAR Scanner; Comparative Results From Helheim Glacier Southeast Greenland and Hubbard Glacier Southeast Alaska  

NASA Astrophysics Data System (ADS)

Tidewater glaciers exhibit dynamic behaviors across a range of spatial and temporal scales, posing a challenge to both in situ and remote sensing observations. In situ measurements capture variability over very short time intervals, but with limited spatial coverage and significant cost and risk to employ. Conversely, airborne and satellite remote sensing is capable of measuring changes over large spatial extents but at limited temporal sampling. Terrestrial LiDAR Scanning (TLS) combines rapid acquisition capabilities of in situ measurements with the broad spatial coverage of traditional remote sensing. This paper describes efforts to develop and field a new long-range (6-10 km) terrestrial full-waveform LiDAR scanner that is optimized for glaciated environments. Our work seeks to gain insights into the processes of glacier flow and terminus dynamics on two of the world's most active tidewater glaciers. Helheim Glacier, a large East Greenland outlet glacier is known to move at speeds >25 m/d near its terminus; rapid readjustments in speed are also know to occur following terminus retreat. Hubbard Glacier, located in southeast Alaska an outlet glacier flowing 90Km out of the St Elias mountains is ~13km across at its terminus, exhibits flow rates up to 5m/d and is advancing and thickening. These two glacial systems have similar characteristics yet represent inverse phases of tidewater glacier activity. Our understanding of these processes is limited by incomplete observational datasets. Most TLS instruments operate in the near-infrared spectrum (1550 nm), which greatly limits range (<150 m) and its application as a tool for long-range standoff glaciology. High spatial and temporal resolution surveys were conducted at Helheim Glacier during the summer of 2012 and 2013 and surveys were conducted at Hubbard Glacier in the spring of 2013. Both were conducted over multi-day periods ranging from 3-7 days. Preliminary results from these surveys have allowed us to quantify short-term horizontal displacement rates and terminus activities at temporal and spatial resolutions previously not possible. Furthermore, these results allow for a comparative analysis of two similar yet different tidewater glacier systems representing altering phases of dynamic activity. Identifying the operational limitations of these sensors in our work is a key guide to the optimal design characteristics for new, improved LiDAR instruments for campaign deployments in glacierized environments.

Finnegan, D. C.; Hamilton, G. S.; Stearns, L. A.; LeWinter, A.; Fowler, A.

2013-12-01

252

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

253

Our vanishing glaciers: One hundred years of glacier retreat in Three Sisters Area, Oregon Cascade Range  

USGS Publications Warehouse

In August 1910, thirty-nine members of the Mazamas Mountaineering Club ascended the peaks of the Three Sisters in central Oregon. While climbing, geologist Ira A. Williams photographed the surrounding scenery, including images of Collier Glacier. One hundred years later, U.S. Geological Survey research hydrologist Jim E. OConnor matched those documented photographs with present day images the result of which is a stunning lapse of glacial change in the Three Sister region. OConnor asserts that glaciers exist by the grace of climate, and through a close examination of the history of the regions glaciers, he provides an intriguing glimpse into the history of geological surveys and glacial studies in the Pacific Northwest, including their connection to significant scientific advances of the nineteenth century. The work of scientists and mountaineers who have monitored and recorded glacier changes for over a century allows us to see dramatic changes in a landscape that is especially sensitive to ongoing climate change.

O'Connor, James E.

2014-01-01

254

Micrometeorological conditions and surface mass and energy fluxes on Lewis Glacier, Mt Kenya, in relation to other tropical glaciers  

NASA Astrophysics Data System (ADS)

The Lewis Glacier on Mt Kenya is one of the best-studied tropical glaciers, but full understanding of the interaction of the glacier mass balance and its climatic drivers has been hampered by a lack of long-term meteorological data. Here we present 2.5 yr of meteorological data collected from the glacier surface from October 2009 to February 2012. The location of measurements is in the upper portion of Lewis Glacier, but this location experiences negative annual mass balance, and the conditions are comparable to those experienced in the lower ablation zones of South American glaciers in the inner tropics. In the context of other glaciated mountains of equatorial East Africa, the summit zone of Mt Kenya shows strong diurnal cycles of convective cloud development as opposed to the Rwenzoris, where cloud cover persists throughout the diurnal cycle, and Kilimanjaro, where clear skies prevail. Surface energy fluxes were calculated for the meteorological station site using a physical mass- and energy-balance model driven by measured meteorological data and additional input parameters that were determined by Monte Carlo optimization. Sublimation rate was lower than those reported on other tropical glaciers, and melt rate was high throughout the year, with the glacier surface reaching the melting point on an almost daily basis. Surface mass balance is influenced by both solid precipitation and air temperature, with radiation providing the greatest net source of energy to the surface. Cloud cover typically reduces the net radiation balance compared to clear-sky conditions, and thus the frequent formation of convective clouds over the summit of Mt Kenya and the associated higher rate of snow accumulation are important in limiting the rate of mass loss from the glacier surface. The analyses shown here form the basis for future glacier-wide mass and energy balance modeling to determine the climate proxy offered by the glaciers of Mt Kenya.

Nicholson, L. I.; Prinz, R.; Mlg, T.; Kaser, G.

2013-08-01

255

Glacier-sea floor interactions during advance-retreat cycles of surge-type glaciers in Svalbard (Invited)  

NASA Astrophysics Data System (ADS)

In Svalbard, many fjord-terminating glaciers are surge-type, and surges profoundly influence fjord-floor landsystems and sediment architecture. Conversely, moraines and other glacigenic landforms influence glacier terminus stability by acting as pinning points and barriers to glacier flow. We use a combination of Synthetic Aperture Radar (SAR) satellite imagery and detailed bathymetric surveys to investigate the evolution of several fjord-terminating glaciers during recent surges, and their relationship with sea floor topography and landforming processes. During surges, glaciers transport large quantities of fjord floor sediment in the form of mobile push moraines, which can form substantial barriers across fjords. These moraines suppress calving during surge advances by acting as pinning points, and encourage glacier stability during early quiescence. Consequently, calving rates do not vary systematically over the course of a surge cycle, despite large variations in glacier flow speeds. Geomorphological and sedimentological data show that many Svalbard surge moraines are multi-generational, and that repeated surges terminated at similar points in the fjord. Unlike land-terminating surge-type glaciers, fjord-terminating glaciers can build sequences of annual push moraines during their quiescent phases. These recessional moraines can form even in front of stagnant glaciers, when their frontal zones undergo stretching in response to longitudinal stress gradients. In conjunction with surge moraines, these provide an important record of advance-retreat dynamics of surge-type glaciers, in some cases over multiple surge cycles. When combined with dating techniques, this landform assemblage can provide important information about the frequency and magnitude of Svalbard surges well beyond the observational record.

Benn, D.; Flink, A.; Lovell, H.; Luckman, A. J.; Noormets, R.; Sevestre, H.

2013-12-01

256

Mountain glaciers in the Mediterranean area and in Africa  

Microsoft Academic Search

Few glaciers or glacierets still exist in the Mediterranean area. The snow line between the Alps and the mountains of North Africa and the Near East must be reconstructed with the help of climatic data. The only glaciers in Africa are on Mt Kenya (covering an area of 0.8 km 2 ), on Kilimanjaro (5 km2) and in the Ruwenzori

B. Messerli

257

Glacier Change in the Rwenzori Mountains, East Africa  

NASA Astrophysics Data System (ADS)

In East Africa glaciers currently exist on Mt. Kilimanjaro and Mt. Kenya, and in the Rwenzori Mountains. While the Mt. Kilimanjaro and Mt. Kenya glaciers have been the subject of many recent studies, the glaciers in the Rwenzori Range are less thoroughly studied. This study reexamines the satellite record of retreat of these glaciers, as well as the climatic factors most responsible for the change. A recent study of the retreat of the Rwenzori glaciers using Landsat images acquired between 1987 and 2003 has been questioned. Using visual mapping and the Normalized Difference Snow Index (NDSI) to analyze Landsat, ASTER and SPOT images, we have re-evaluated the ice areas for the period 1987 to 2006. After identifying sources for possible error, our mapping indicates that the glaciers in the Rwenzori have shrunk from an area of 2.55 km2 in 1987 to 1.31 km2 in 2006. Glacier retreat in the Rwenzori from 1906 to 1990 showed a strong spatial correlation with potential increase in shortwave radiation due to decreased cloud cover as a consequence of a shift to drier conditions in the region. Whether or not recent glacier retreat shows a similar spatial correlation is under investigation.

Kincaid, J. L.; Klein, A. G.

2007-12-01

258

Rock glaciers in the South Shetland Islands, Western Antarctica  

Microsoft Academic Search

Rock glaciers are found in the peripheral regions of Antarctica particularly in the Antarctic Peninsula region. Study of these features is relevant for the palaeoenvironmental reconstruction of maritime Antarctica because they are indicators of permafrost and periglacial conditions. This paper reports and analyzes the results of an inventory of rock glaciers and protalus lobes in the South Shetland Islands. Nine

Enrique Serrano; Jernimo Lpez-Mart??nez

2000-01-01

259

Sensitivity and response of Bhutanese glaciers to atmospheric warming  

NASA Astrophysics Data System (ADS)

Glacierized change in the Himalayas affects river-discharge, hydro-energy and agricultural production, and Glacial Lake Outburst Flood potential, but its quantification and extent of impacts remains highly uncertain. Here we present conservative, comprehensive and quantitative predictions for glacier area and meltwater flux changes in Bhutan, monsoonal Himalayas. In particular, we quantify the uncertainties associated with the glacier area and meltwater flux changes due to uncertainty in climate data, a critical problem for much of High Asia. Based on a suite of gridded climate data and a robust glacier melt model, our results show that glacier area and meltwater change projections can vary by an order of magnitude for different climate datasets. However, the most conservative results indicate that, even if climate were to remain at the present-day mean values, almost 10% of Bhutan's glacierized area would vanish and the meltwater flux would drop by as much as 30%. Under the conservative scenario of an additional 1C regional warming, glacier retreat is going to continue until about 25% of Bhutan's glacierized area will have disappeared and the annual meltwater flux, after an initial spike, would drop by as much as 65%.

Rupper, Summer; Schaefer, Joerg M.; Burgener, Landon K.; Koenig, Lora S.; Tsering, Karma; Cook, Edward R.

2012-10-01

260

What influences climate and glacier change in southwestern China?  

Microsoft Academic Search

The subject of climate change in the Tibetan Plateau (TP) and Himalayas has taken on increasing importance because of the availability of water resources from their mountain glaciers (Immerzeel et al 2010). Many of the glaciers over these regions have been retreating, while some are advancing and stable (Yao et al 2004, Scherler et al 2011). Other studies report that

Teppei J. Yasunari

2011-01-01

261

Nanoparticulate bioavailable iron minerals in icebergs and glaciers R. RAISWELL  

E-print Network

Nanoparticulate bioavailable iron minerals in icebergs and glaciers R. RAISWELL 1 , L. G. BENNING 1, Bristol University, Bristol BS8 1SS, UK ABSTRACT Ice-hosted sediments in glaciers and icebergs from by icebergs to the Southern Ocean is comparable to the flux of soluble, bioavailable Fe from aeolian dust

Benning, Liane G.

262

Recent glacier retreat and climate trends in Cordillera Huaytapallana, Peru  

Microsoft Academic Search

Abstract We analyzed 19 annual Landsat Thematic Mapper images from 1984 to 2011 to determine changes of the glaciated surface and snow line elevation in six mountain areas of the Cordillera Huaytapallana range in Peru. In contrast to other Peruvian mountains, glacier retreat in these mountains has been poorly documented, even though this is a heavily glaciated area. These glaciers

J. I. Lpez-Moreno; S. Fontaneda; J. Bazo; J. Revuelto; C. Azorin-Molina; B. Valero-Garcs; E. Morn-Tejeda; S. M. Vicente-Serrano; R. Zubieta; J. Alejo-Cochachn

2013-01-01

263

Recent glacier retreat and climate trends in Cordillera Huaytapallana, Peru  

Microsoft Academic Search

We analyzed 19 annual Landsat Thematic Mapper images from 1984 to 2011 to determine changes of the glaciated surface and snow line elevation in six mountain areas of the Cordillera Huaytapallana range in Peru. In contrast to other Peruvian mountains, glacier retreat in these mountains has been poorly documented, even though this is a heavily glaciated area. These glaciers are

2013-01-01

264

GLACIER HAZARD ASSESSMENT IN MOUNTAINS USING SATELLITE OPTICAL DATA  

Microsoft Academic Search

Process interactions and chain reactions, the shift of cryospheric hazard zones due to climate change, and the far reach of glacier disasters make it necessary to apply modern remote sensing techniques for the assessment of glacier hazards. In the present contribution we provide an over- view of spaceborne optical methods suitable for glacial hazard assessment and disaster manage- ment. Digital

Andreas Kb; Christian Huggel; Samuel Guex; Frank Paul; Nadine Salzmann; Kostia Schmutz; Demian Schneider; Yvo Weidmann

2005-01-01

265

Tropical climate and glacier hydrology: a case study in Bolivia  

Microsoft Academic Search

Runoff from intertropical glaciers is highly variable, indicating that they are greatly affected by climatic changes peculiar to tropical climates. The 3 km2 basin presented in this case study lies in the Cordillera Real of Bolivia and is 77% covered by glacier ice, ranging in elevation from 6000 to 4830 m a.s.l. A comparison of 2 years of study demonstrates

P. Ribstein; E. Tiriau; B. Francou; R. Saravia

1995-01-01

266

The GLIMS Glacier Database: a spatio-temporal database  

E-print Network

The GLIMS Glacier Database: a spatio-temporal database implemented using Open Source tools Bruce countries #12;#12;#12;#12;#12;System components PostgreSQL (relational database) PostGIS (geospatial) GDAL (Geospatial Data Abstraction Library) Perl, PHP, Shapelib, ... #12;GLIMS Glacier Database System

Raup, Bruce H.

267

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.

Balog, James; Pfeffer, Tad; Survey, Extreme I.

268

Mapping the World's glaciers from space: Results from the ESA project GlobGlacier  

NASA Astrophysics Data System (ADS)

The ESA project GlobGlacier aims at making a substantial contribution to current efforts of mapping the World's glaciers from satellite data using (semi-)automated techniques. For this purpose a number of key regions have been identified in close cooperation with the user group of the project and based on a set of criteria (e.g. filling the gaps in current inventories, or their potential contribution to sea-level rise). Apart from glacier outlines and terminus positions, a couple of further data products are created by the project: late summer snowlines (LSSL), topographic information, elevation changes and velocity fields. While most of the products are created from optical sensors like Landsat TM/ETM+ as available from the glovis.usgs.gov website, some of them will also utilize radar sensors and LIDAR data. The inventory data are mainly created for the year 2000 (+/- a few years) to have a good temporal match with the SRTM DEM. In selected regions, multi-temporal data sets will be used for change assessment. The new data sets will be integrated in the existing databases of GLIMS and WGMS. With this contribution we provide an overview of the current status of the project as well as its major achievements. Outlines for several thousand glaciers have already been created in many of the key regions. This includes parts of Alaska (Chigmit Mts., Kenai Peninsula, Chugach Mts.), Arctic Canada (Devon, Bylot, Baffin Island), West Greenland (Disko Island, Nuussuaq, Svartenhuk), Norway (Svartisen, Jostedalsbreen), India (Kashmir) and the European Alps. The products LSSL, topography and elevation changes were also produced for several hundred glaciers and surface velocity fields have been derived for more than 50 glaciers from radar and optical sensors. Topographic information for each glacier is obtained from freely available DEMs (e.g. SRTM, ASTER GDEM) and elevation changes are derived from DEM differencing as well as repeat track altimetry using the GLAS and RA-2 instruments. Some of the key regions act as integration sites where more than one product is created.

Paul, Frank

2010-05-01

269

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

270

The physical basis of glacier volume-area scaling  

USGS Publications Warehouse

Ice volumes are known for only a few of the roughly 160,000 glaciers worldwide but are important components of many climate and sea level studies which require water flux estimates. A scaling analysis of the mass and momentum conservation equations shows that glacier volumes can be related by a power law to more easily observed glacier surface areas. The relationship requires four closure choices for the scaling behavior of glacier widths, slopes, side drag and mass balance. Reasonable closures predict a volume-area scaling exponent which is consistent with observations, giving a physical and practical basis for estimating ice volumes. Glacier volume is insensitive to perturbations in the mass balance scaling, but changes in average accumulation area ratios reflect significant changes in the scaling of both mass balance and ice volume. Copyright 1997 by the American Geophysical Union.

Bahr, D.B.; Meier, M.F.; Peckham, S.D.

1997-01-01

271

Microbial Life beneath a High Arctic Glacier  

PubMed Central

The debris-rich basal ice layers of a high Arctic glacier were shown to contain metabolically diverse microbes that could be cultured oligotrophically at low temperatures (0.3 to 4C). These organisms included aerobic chemoheterotrophs and anaerobic nitrate reducers, sulfate reducers, and methanogens. Colonies purified from subglacial samples at 4C appeared to be predominantly psychrophilic. Aerobic chemoheterotrophs were metabolically active in unfrozen basal sediments when they were cultured at 0.3C in the dark (to simulate nearly in situ conditions), producing 14CO2 from radiolabeled sodium acetate with minimal organic amendment (?38 ?M C). In contrast, no activity was observed when samples were cultured at subfreezing temperatures (??1.8C) for 66 days. Electron microscopy of thawed basal ice samples revealed various cell morphologies, including dividing cells. This suggests that the subglacial environment beneath a polythermal glacier provides a viable habitat for life and that microbes may be widespread where the basal ice is temperate and water is present at the base of the glacier and where organic carbon from glacially overridden soils is present. Our observations raise the possibility that in situ microbial production of CO2 and CH4 beneath ice masses (e.g., the Northern Hemisphere ice sheets) is an important factor in carbon cycling during glacial periods. Moreover, this terrestrial environment may provide a model for viable habitats for life on Mars, since similar conditions may exist or may have existed in the basal sediments beneath the Martian north polar ice cap. PMID:10919772

Skidmore, Mark L.; Foght, Julia M.; Sharp, Martin J.

2000-01-01

272

Probabilistic correction of precipitation measurement errors using a Bayesian Model Average Approach applied for the estimation of glacier accumulation  

NASA Astrophysics Data System (ADS)

Precipitation is a major component of the water cycle that returns atmospheric water to the ground. Without precipitation there would be no water cycle, all the water would run down the rivers and into the seas, then the rivers would dry up with no fresh water from precipitation. Although precipitation measurement seems an easy and simple procedure, it is affected by several systematic errors which lead to underestimation of the actual precipitation. Hence, precipitation measurements should be corrected before their use. Different correction approaches were already suggested in order to correct precipitation measurements. Nevertheless, focusing on the outcome of a single model is prone to statistical bias and underestimation of uncertainty. In this presentation we propose a Bayesian model average (BMA) approach for correcting rain gauge measurement errors. In the present study we used meteorological data recorded every 10 minutes at the Condoriri station in the Bolivian Andes. Comparing rain gauge measurements with totalisators rain measurements it was possible to estimate the rain underestimation. First, different deterministic models were optimized for the correction of precipitation considering wind effect and precipitation intensities. Then, probabilistic BMA correction was performed. The corrected precipitation was then separated into rainfall and snowfall considering typical Andean temperature thresholds of -1C and 3C. Hence, precipitation was separated into rainfall, snowfall and mixed precipitation. Then, relating the total snowfall with the glacier ice density, it was possible to estimate the glacier accumulation. Results show a yearly glacier accumulation of 1200 mm/year. Besides, results confirm that in tropical glaciers winter is not accumulation period, but a low ablation one. Results show that neglecting such correction may induce an underestimation higher than 35 % of total precipitation. Besides, the uncertainty range may induce differences up to 200 mm/year. This research is developed within the GRANDE project (Glacier Retreat impact Assessment and National policy Development), financed by SATREPS from JST-JICA.

Moya Quiroga, Vladimir; Mano, Akira; Asaoka, Yoshihiro; Udo, Keiko; Kure, Shuichi; Mendoza, Javier

2013-04-01

273

Botanical Evidence of the Modern History of Nisqually Glacier, Washington  

USGS Publications Warehouse

A knowledge of the areas once occupied by mountain glaciers reveals at least part of the past behavior of these glaciers. From this behavior, inferences of past climate can be drawn. The maximum advance of Nisqually Glacier in the last thousand years was located, and retreat from this point is believed to have started about 1840. The maximum downvalley position of the glacier is marked by either a prominent moraine or by a line of difference between stands of trees of strikingly different size and significantly different age. The thousand-year age of the forest beyond the moraine or line between abutting stands represents the minimum time since the surface was glaciated. This age is based on the age of the oldest trees, plus an estimated interval required for the formation of humus, plus evidence of an ancient fire, plus an interval of deposition of pyroclastics. The estimate of the date when Nisqually Glacier began to retreat from its maximum advance is based upon the ages of the oldest trees plus an interval of 5 years estimated as the time required for the establishment of trees on stable moraines. This interval was derived from a study of the ages of trees growing at locations of known past positions of the glacier. Reconnaissance studies were made on moraines formed by Emmons and Tahoma Glaciers. Preliminary analyses of these data suggest that Emmons Glacier started to recede from its maximum advance in about 1745. Two other upvalley moraines mark positions from which recession started about 1849 and 1896. Ages of trees near Tahoma Glacier indicate that it started to recede from its position of maximum advance in about 1635. About 1835 Tahoma Glacier started to recede again from another moraine formed by a readvance that ter minated near the 1635 position.

Sigafoos, Robert S.; Hendricks, E.L.

1961-01-01

274

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

Microsoft Academic Search

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

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

2008-01-01

275

Glacier variations in Breheimen, southern Norway: relative-age dating of Holocene moraine complexes at six high-altitude glaciers  

Microsoft Academic Search

Lichenometric evidence and Schmidt hammer R-values are used to date Holocene moraine sequences in front of six high-altitude (> 1500 m) glaciers in Breheimen, central southern Norway. At three glacier forelands with southerly aspects (Hgsetbreen, Vestre Hybre and stre Hybre), relatively small (?4 m high) discrete boulder moraine ridges are shown to date from the Little Ice Age. The remaining

Richard A. Shakesby; John A. Matthews; Stefan Winkler

2004-01-01

276

A comparison of surface renewal theory with the observed roughness length for temperature on a melting glacier surface  

NASA Astrophysics Data System (ADS)

The roughness lengths for momentum and temperature are calculated using the profile method on amelting glacier surface. Data from a 5-level 9-m meteorological mastpositioned near the edge of Breidamerkurjkull, an outlet glacier of the Vatnajkull ice cap Iceland, are used for the calculations. The data are selected to avoid the presence of the katabatic wind speedmaximum which would otherwise alter the scaling laws of the surface layer. The surface roughness length for momentum is determined to be 1.0 mm, similar to other estimates made on flat melting ice surfaces. The surface roughness length for temperature is found to be in good agreement with previously proposed surface renewal theories for the observed roughness Reynolds number range of 30 * 70.

Denby, Bruce; Snellen, Henk

277

Combining satellite multispectral image data and a digital elevation model for mapping debris-covered glaciers  

Microsoft Academic Search

Automated glacier mapping from satellite multispectral image data is hampered by debris cover on glacier surfaces. Supraglacial debris exhibits the same spectral properties as lateral and terminal moraines, fluvioglacial deposits, and bedrock outside the glacier margin, and is thus not detectable by means of multispectral classification alone. Based on the observation of low slope angles for debris-covered glacier tongues, we

Frank Paul; Christian Huggel; Andreas Kb

2004-01-01

278

ADAPTING TO THE REALITY OF CLIMATE CHANGE AT GLACIER NATIONAL PARK, MONTANA, USA  

Microsoft Academic Search

The glaciers of Glacier National Park (GNP) are disappearing rapidly and likely will be gone by 2030. These alpine glaciers have been continuously present for approximately 7,000 years so their loss from GNP in another 25 years underscores the significance of current climate change. There are presently only 27 glaciers remaining of the 150 estimated to have existed when GNP

Daniel B. Fagre

279

Assessing the Impact of Retreating Glaciers on Dry-Season Discharge in a Tropical Andean Watershed  

Microsoft Academic Search

Receding glaciers in the tropical Andes are causing concerns for future water supply in a region with thermal homogeneity and a strongly seasonal precipitation cycle. Dry season runoff from glacierized catchments is buffered by glacier melt that is not completely replaced by seasonal precipitation. Our objective is to trace the changing contribution of glacier meltwater to stream flow and to

B. G. Mark; J. M. McKenzie

2006-01-01

280

Climate Change Impacts on Water Resources of Nepal with Reference to the Himalayan Glaciers  

Microsoft Academic Search

The impacts of climate change on water resources of Nepal with reference to snow and glacier were assessed applying empirical glacier mass model. Specific glacier mass balance values were calculated with different rates of temperature rise. The analysis has revealed that the glaciers in the Nepal Himalayas are shrinking rapidly and almost all of them may disappear within less than

N. Chaulagain

2009-01-01

281

Historical fluctuations of the Gualas and Reicher Glaciers, North Patagonian Icefield, Chile  

Microsoft Academic Search

Dendrochronology was used to date historical fluctuations of the little-visited Gualas and Reicher Glaciers on the North Patagonian Icefield in southern Chile. Vegetation trimlines dating to ad 1876, 1909 and 1954 show that glacier downwasting and retreat mirrored the patterns found at the neighbouring San Rafael and San Quintin Glaciers. Intermediate stages of recession of the Gualas and Reicher Glaciers

Stephan Harrison; Vanessa Winchester

1998-01-01

282

Sudden increase in tidal response linked to calving and acceleration at a large Greenland outlet glacier  

Microsoft Academic Search

Large calving events at Greenland's largest outlet glaciers are associated with glacial earthquakes and near-instantaneous increases in glacier flow speed. At some glaciers and ice streams, flow is also modulated in a regular way by ocean tidal forcing at the terminus. At Helheim Glacier, analysis of geodetic data shows decimeter-level periodic position variations in response to tidal forcing. However, we

Julia de Juan; Pedro Elsegui; Meredith Nettles; Tine B. Larsen; James L. Davis; Gordon S. Hamilton; Leigh A. Stearns; Morten L. Andersen; Gran Ekstrm; Andreas P. Ahlstrm; Lars Stenseng; S. Abbas Khan; Ren Forsberg

2010-01-01

283

Bathymetric Controls On Observed Tidewater Glacier Retreat In Northwest Greenland  

NASA Astrophysics Data System (ADS)

Although many of the largest glaciers in Greenland are losing mass, the large variability in observed mass wastage of the remaining glaciers clouds interpretation of the proposed external forcings, such as warming of the ocean or atmosphere. Some glaciers are accelerating and thinning while other nearby glaciers advance and gain mass. Recent efforts suggest that increased ocean temperatures may be responsible for the observed glacial retreat in Greenland and Antarctica through increased basal melting beneath floating ice tongues and vertical ice faces of tidewater glaciers. Basal melting may contribute significantly to calving and thinning, and to an eventual speeding up of the glacier, resulting in thinning further inland. Knowledge of fjord geometry is crucial for ice-ocean interaction because the availability of ocean heat to the ice will be restricted by narrow sills and shallow grounding lines. We investigate whether the variability in observed changes among Greenland glaciers can be partially explained by variation in fjord geometry. Some features of a fjord that could influence the ice-ocean system include the depth of the grounding line, the presence of sills, sloping bed, and the water cavity shape beneath floating ice. New estimates of fjord bathymetries in northwest Greenland, using airborne gravimetry measurements from NASA Operation IceBridge flights, are compared to estimates of ice acceleration and mass wastage of neighboring glaciers. We investigate the correlation between fjord geometry features and several glacier parameters, such as surface velocity and elevation changes. We determine that the geometry of glacial fjords play a large role in determining the stability of outlet glaciers. Deep sills and deep terminus grounding lines will allow greater interaction with the deep and warm Atlantic water off the shelf break. For two neighboring glaciers in northwest Greenland, we find that the glacier with a deeper grounding line, and presumably in contact with more warm water, is flowing faster and experiencing larger mass loss over the past decade. Such broad correlations between grounding line depths and mass wastage are a starting point in an effort to understand the variability of observed retreat of outlet glaciers in northern Greenland.

Porter, D. F.; Tinto, K. J.; Boghosian, A.; Cochran, J. R.; Bell, R. E.

2013-12-01

284

Alaska tidewater glacier velocities and frontal ablation, 1985-2012  

NASA Astrophysics Data System (ADS)

Despite their potential importance to sea level rise, little is known about 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. Frontal ablation contributes about half of the mass loss from the ice sheets, and lack of both understanding of and data on these important processes has been cited as a major hindrance to accurate predictions of global sea level rise. First, we present a 64 year record of length change for 50 Alaska tidewater glaciers, derived from manually digitizing aerial mapping photographs and Landsat scenery. Then, we present a 27 year record of surface velocity and frontal ablation for 20 Alaska tidewater glaciers (representing 80% of the total tidewater glacier area in the region), derived using a feature tracking algorithm, all available cloud-free Landsat 5 and 7 scenes, and estimates of glacier ice thickness derived from an inversion of surface topography. In general, the 50 glaciers studied retreated over the period 1948-2012, though these changes are not constant - several glaciers both retreated and advanced over the time period. We find the total mean rate of frontal ablation for these 20 glaciers over the period 1985-2012 is 16.26.5$ Gt a-1; scaling this result by area to the remaining 30 tidewater glaciers in Alaska, we estimate a mean rate of frontal ablation of 18.37.3 Gt a-1 over the period 1985-2012. Two glaciers in particular, Hubbard and Columbia, account for over 50% of the frontal ablation signal of the set of 20 glaciers. Seasonal changes in surface velocity match well with seasonal changes in length, indicating that rates of frontal ablation do not remain constant throughout the year. Despite coming from 15% of the glacierized area in the region, frontal ablation is a significant contributor to the regional mass budget. We estimate a specific mass loss through frontal ablation for all Alaska glaciers of 0.21 m w.e. a-1, equivalent to estimates from Svalbard, and over three times the rate for Greenland.

McNabb, R. W.; Hock, R.

2013-12-01

285

Exploring similarities between tidewater and ice sheet outlet glaciers  

NASA Astrophysics Data System (ADS)

Tidewater and outlet glaciers pose a serious challenge to glaciologists because of their complicated behavior. Yet, they exhibit some of the largest changes observed in glacial systems, often defying regional trends of nearby land-terminating ice masses. For example the Chugach Range of Alaska, while generally losing ice mass, contains one growing tidewater glacier. Also, about 50% of the current mass loss there is due to the rapidly retreating Columbia Glacier. In Glacier Bay, several tidewater glaciers are advancing while land terminating and lake calving glaciers are rapidly wasting away. We will explore some of the common features found between temperate tidewater glaciers and the cold or polythermal outlet glaciers of the big ice sheets. These commonalities include patterns of ice draw-down, particularly far upstream, and acceleration of ice flow during the retreat phase that propagates much farther upstream than suggested by effects of longitudinal coupling. Rapid retreats are initiated at the glacier terminus and we suggest that they are linked to warming ocean temperatures and glacial freshwater runoff. We will also outline the modeling challenges for the upstream propagation of a drawdown event. These require a full treatment of the three dimensional Stokes equations. However, it is not clear how to treat the basal boundary condition and the possibility of temporal changes at the ice base. A particular challenge for outlet glacier systems is posed by free surfaces, such as the grounding line or the cold-temperate-surface (CTS). One striking feature of tidewater glaciers is their evolution through a tidewater glacier cycle of rapid retreat and slow advance as proposed by Austin Post. This cycle is well documented for Alaska's tidewater systems, and we suggest that the possibility of such a cycle should be explored for ice sheet outlet glaciers. The often asynchronous behavior of these systems poses a challenge for the assessment of regional or global ice volume changes. Similarly, ice sheet mass balance can be dominated by a few rapidly changing outlet systems. Such systems must be carefully examined for their disproportionate effects on volume change and sea level studies.

Truffer, M.; Motyka, R.; Echelmeyer, K.

2005-12-01

286

Latest Pleistocene and Holocene glacier fluctuations on Mount Baker, Washington  

NASA Astrophysics Data System (ADS)

Glaciers on stratovolcanoes of the Pacific Northwest of North America offer opportunities for dating late Pleistocene and Holocene glacier advances because tephra and fossil wood are common in lateral moraines and in glacier forefields. We capitalize on this opportunity by examining the Holocene glacial record at Mount Baker, an active stratovolcano in northwest Washington. Earlier workers concluded that glaciers on Mount Baker during the early Holocene were more extensive than during the Little Ice Age and hypothesized that the explanation lay in unusual climatic or hypsometric effects peculiar to large volcanoes. We show that the main argument for an early Holocene glacier advance on Mount Baker, namely the absence of ca 10,000-year-old tephra on part of the south flank of the mountain, is incorrect. Moreover, a lake-sediment core indicates that a small cirque moraine previously thought be of early Holocene age is also likely older than the tephra and consequently of late Pleistocene age. Lateral and end moraines and wood mats ca 2 km downvalley of the present snout of Deming Glacier indicate that an advance during the Younger Dryas interval was little more extensive than the climactic Little Ice Age advance. Tephra and wood between tills in the left lateral moraine of Easton Glacier suggest that ice on Mount Baker was restricted in the early Holocene and that Neoglaciation began ca 6 ka. A series of progressively more extensive Neoglacial advances, dated to about 2.2, 1.6, 0.9, and 0.4 ka, are recorded by stacked tills in the right lateral moraine of Deming Glacier. Intervening retreats were long enough to allow establishment of forests on the moraine. Wood mats in moraines of Coleman and Easton glaciers indicate that Little Ice Age expansion began before 0.7 ka and was followed by retreat and a readvance ca 0.5 ka. Tree-ring and lichen data indicate glaciers on the south side of the mountain reached their maximum extents in the mid-1800s. The similarity between glacier fluctuations at Mount Baker and those elsewhere in the Cascades and in British Columbia suggests a coherent history of Holocene climate change over a broad area of the western Cordillera. We found no evidence that glaciers on stratovolcanoes behave differently than glaciers elsewhere.

Osborn, Gerald; Menounos, Brian; Ryane, Chanone; Riedel, Jon; Clague, John J.; Koch, Johannes; Clark, Douglas; Scott, Kevin; Davis, P. Thompson

2012-08-01

287

Instrument for Analysis of Greenland's Glacier Mills  

NASA Technical Reports Server (NTRS)

A new instrument is used to study the inner workings of Greenland s glacier mills by riding the currents inside a glacier s moulin. The West Greenland Moulin Explorer instrument was deployed into a tubular shaft to autonomously record temperature, pressure, 3D acceleration, and location. It is built with a slightly positive buoyancy in order to assist in recovery. The unit is made up of several components. A 3-axis MEMS (microelectromechanical systems) accelerometer with 0.001-g resolution forms the base of the unit. A pressure transducer is added that is capable of withstanding 500 psi (=3.4 MPa), and surviving down to -40 C. An Iridium modem sends out data every 10 minutes. The location is traced by a GPS (Global Positioning System) unit. This GPS unit is also used for recovery after the mission. Power is provided by a high-capacity lithium thionyl chloride D-sized battery. The accelerometer is housed inside a cylindrical, foot-long (=30 cm) polyvinyl chloride (PVC) shell sealed at each end with acrylic. The pressure transducer is attached to one of these lids and a MEMS accelerometer to the other, recording 100 samples per second per axis.

Behar, Alberto E.; Matthews, Jaret B.; Tran, Hung B.; Steffen, Konrad; McGrath, Dan; Phillips, Thomas; Elliot, Andrew; OHern, Sean; Lutz, Colin; Martin, Sujita; Wang, Henry

2010-01-01

288

Glacier-like forms on Mars  

NASA Astrophysics Data System (ADS)

Over 1300 glacier-like forms (GLFs) are located in Mars' mid-latitudes. These GLFs are visually similar to terrestrial valley glaciers, being predominantly composed of ice-dust mixtures and showing signs of downhill viscous deformation and of an expanded former extent. However, several fundamental aspects of their behaviour are virtually unknown, including temporal and spatial variations in mass balance, ice motion, landscape erosion and deposition, and hydrology. Here, we investigate the physical glaciology of martian GLFs. We use satellite-based images of specific examples and case studies to build on existing knowledge relating to: (i) GLF current and former extent, exemplified via a GLF located in Phlegra Montes; (ii) indicators of GLF motion, focusing on the presence of surface crevasses on several GLFs; (iii) processes of GLF debris transfer, focusing on mapping and interpreting boulder trains on one GLF located in Protonilus Mensae, the analysis of which suggests a minimum GLF flow speed of 7.5 mm a-1, and (iv) GLF hydrology, focusing on possible supraglacial gulley networks on several GLFs. On the basis of this information we summarise the current state of knowledge of the glaciology of martian GLFs and identify future research avenues.

Hubbard, B.; Souness, C.; Brough, S.

2014-06-01

289

What influences climate and glacier change in southwestern China?  

NASA Astrophysics Data System (ADS)

The subject of climate change in the Tibetan Plateau (TP) and Himalayas has taken on increasing importance because of the availability of water resources from their mountain glaciers (Immerzeel et al 2010). Many of the glaciers over these regions have been retreating, while some are advancing and stable (Yao et al 2004, Scherler et al 2011). Other studies report that some glaciers in the Himalayas show acceleration of their shrinkage (e.g., Fujita and Nuimura 2011). However, the causes of glacier melting are still difficult to grasp because of the complexity of climatic change and its influence on glacier issues. Despite this, it is vital that we pursue further study to enable future predictions of glacier changes. The paper entitled 'Climate and glacier change in southwestern China during the past several decades' by Li et al (2011) provided carefully analyzed, quality controlled, long-term data on atmospheric temperature and precipitation during the period 1961-2008. The data were obtained from 111 Chinese stations. The researchers performed systematic analyses of temperature and precipitation over the whole southwestern Chinese domain. They discussed those changes in terms of other meteorological components such as atmospheric circulation patterns, radiation and altitude difference, and then showed how these factors could contribute to climate and glacier changes in the region. Air temperature and precipitation are strongly associated with glacier mass balance because of heat balance and the addition of mass when it snows. Temperature warming trends over many places in southwestern China were unequivocally dominant in all seasons and at higher altitudes. This indicates that the heat contribution to the glaciers has been increasing. On the other hand, precipitation has a wider variability in time and space. It is more difficult to clearly understand the effect of precipitation on the climate and glacier melting characteristics in the whole of southwestern China as a collective view. However, the precipitation patterns in southwestern China are probably modulated by climate feedbacks through many factors. Precipitation seasonality may also affect the climatic sensitivity of glacier mass balance (Fujita 2008). In addition to the authors' main focus above, other factors, also probably directly and indirectly, influence the climate and glacier mass balance changes. Those factors are: (a) The debris-covered effect which heats (if it is thin) or insulates (if it is thick) the ice below the debris; it probably causes no uniform response on glacier melting (Scherler et al 2011); (b) Interaction between glacial lakes and exposed ice parts on glaciers (e.g., Sakai et al 2009, Fujita et al 2009); (c) The atmospheric heating effect over the foothills of the Himalayas due to the Atmospheric Brown Cloud (ABC), including absorbing aerosols such as black carbon, dust and organic matters (Ramanathan et al 2007), the so called Elevated Heat Pump (EHP) effect suggested by Lau et al (2006, 2010); (d) The snow darkening effect over non debris-covered parts of glaciers as the absorbing aerosol depositions reduce snow albedo and accelerate snow melting by absorbing more solar energy at the snow surface (Warren and Wiscombe 1980, Flanner et al 2007, 2009, Yasunari et al 2010, Qian et al 2011); (e) Another kind of snow darkening effect over non debris-covered glaciers due to the growth of biological activities, with dark-colored materials on glaciers also reducing snow albedo (Takeuchi et al 2001); (f) Other factors on snow albedo reductions such as snow grain size, specific surface area and depth changes, melt-water effect on snow, and changes in solar illumination conditions (e.g., Wiscombe and Warren 1980, Flanner et al 2006, Yasunari et al 2011, Aoki et al 1999, 2011); and finally, (g) Feedbacks via interactions between the snow surface and atmosphere including all the factors above. What I'd like to emphasize is that the atmospheric warming trend indicated by Li et al (2011) is robust and very likely associated with the dominant character

Yasunari, Teppei J.

2011-12-01

290

Latest Pleistocene and Holocene glacier variations in the European Alps  

NASA Astrophysics Data System (ADS)

In the Alps, climatic conditions reflected in glacier and rock glacier activity in the earliest Holocene show a strong affinity to conditions in the latest Pleistocene (Younger Dryas). Glacier advances in the Alps related to Younger Dryas cooling led to the deposition of Egesen stadial moraines. Egesen stadial moraines can be divided into three or in some cases even more phases (sub-stadials). Moraines of the earliest and most extended advance, the Egesen maximum, stabilized at 12.2 1.0 ka based on 10Be exposure dating at the Schnferwall (Tyrol, Austria) and the Julier Pass-outer moraine (Switzerland). Final stabilization of moraines at the end of the Egesen stadial was at 11.3 0.9 ka as shown by 10Be data from four sites across the Alps. From west to east the sites are Piano del Praiet (northwestern Italy), Grosser Aletschgletscher (central Switzerland), Julier Pass-inner moraine (eastern Switzerland), and Val Viola (northeastern Italy). There is excellent agreement of the 10Be ages from the four sites. In the earliest Holocene, glaciers in the northernmost mountain ranges advanced at around 10.8 1.1 ka as shown by 10Be data from the Kartell site (northern Tyrol, Austria). In more sheltered, drier regions rock glacier activity dominated as shown, for example, at Julier Pass and Larstig valley (Tyrol, Austria). New 10Be dates presented here for two rock glaciers in Larstig valley indicate final stabilization no later than 10.5 0.8 ka. Based on this data, we conclude the earliest Holocene (between 11.6 and about 10.5 ka) was still strongly affected by the cold climatic conditions of the Younger Dryas and the Preboreal oscillation, with the intervening warming phase having had the effect of rapid downwasting of Egesen glaciers. At or slightly before 10.5 ka rapid shrinkage of glaciers to a size smaller than their late 20th century size reflects markedly warmer and possibly also drier climate. Between about 10.5 ka and 3.3 ka conditions in the Alps were not conducive to significant glacier expansion except possibly during rare brief intervals. Past tree-line data from Kaunertal (Tyrol, Austria) in concert with radiocarbon and dendrochronologically dated wood fragments found recently in the glacier forefields in both the Swiss and Austrian Alps points to long periods during the Holocene when glaciers were smaller than they were during the late 20th century. Equilibrium line altitudes (ELA) were about 200 m higher than they are today and about 300 m higher in comparison to Little Ice Age (LIA) ELAs. The Larstig rock glacier site we dated with 10Be is the type area for a postulated mid-Holocene cold period called the Larstig oscillation (presumed age about 7.0 ka). Our data point to final stabilization of those rock glaciers in the earliest Holocene and not in the middle Holocene. The combined data indicate there was no time window in the middle Holocene long enough for rock glaciers of the size and at the elevation of the Larstig site to have formed. During the short infrequent cold oscillations between 10.5 and 3.3 ka small glaciers (less than several km 2) may have advanced to close to their LIA dimensions. Overall, the cold periods were just too short for large glaciers to advance. After 3.3 ka, climate conditions became generally colder and warm periods were brief and less frequent. Large glaciers (for example Grosser Aletschgletscher) advanced markedly at 3.0-2.6 ka, around 600 AD and during the LIA. Glaciers in the Alps attained their LIA maximum extents in the 14th, 17th, and 19th centuries, with most reaching their greatest LIA extent in the final 1850/1860 AD advance.

Ivy-Ochs, Susan; Kerschner, Hanns; Maisch, Max; Christl, Marcus; Kubik, Peter W.; Schlchter, Christian

2009-10-01

291

Glacier changes in the Big Naryn basin, Central Tian Shan  

NASA Astrophysics Data System (ADS)

A glacier inventory referring to the year 2007 was created for the Big Naryn basin based on satellite imagery. The 507 glaciers had a total area of 471 km. Compared to the Soviet glacier inventory based on data from the mid 20th century, the total glacier area decreased by 23.4%. The shrinkage varies from 14% to 42% between individual mountain ranges. We discuss the possible causes for this considerable variation by analyzing and interpreting topographic parameters and differences between seven sub-regions.On three glaciers, ice thickness was derived by ground penetrating radar (GPR) measurements on the glacier tongues and by surface slope using a simplified ice mechanical approach on the upper parts. We estimate the total ice volume of the basin for both inventories using volume-area scaling. Our results show a current glacier volume of 26.0-33.3 km. A total of 6.6-8.4 km (20%) have been lost since the mid 20th century. The water equivalent of 5.9-7.6 km was transformed into excess discharge and contributed to at least 7.3-9.2% of total runoff in the considered period.

Hagg, W.; Mayer, C.; Lambrecht, A.; Kriegel, D.; Azizov, E.

2013-11-01

292

Glacier calving, dynamics, and sea-level rise. Final report  

SciTech Connect

The present-day calving flux from Greenland and Antarctica is poorly known, and this accounts for a significant portion of the uncertainty in the current mass balance of these ice sheets. Similarly, the lack of knowledge about the role of calving in glacier dynamics constitutes a major uncertainty in predicting the response of glaciers and ice sheets to changes in climate and thus sea level. Another fundamental problem has to do with incomplete knowledge of glacier areas and volumes, needed for analyses of sea-level change due to changing climate. The authors proposed to develop an improved ability to predict the future contributions of glaciers to sea level by combining work from four research areas: remote sensing observations of calving activity and iceberg flux, numerical modeling of glacier dynamics, theoretical analysis of the calving process, and numerical techniques for modeling flow with large deformations and fracture. These four areas have never been combined into a single research effort on this subject; in particular, calving dynamics have never before been included explicitly in a model of glacier dynamics. A crucial issue that they proposed to address was the general question of how calving dynamics and glacier flow dynamics interact.

Meier, M.F.; Pfeffer, W.T.; Amadei, B.

1998-08-01

293

Glacier changes during the last forty years in the Tarim Interior River basin, northwest China  

Microsoft Academic Search

By comparing digitized glacier outlines from the Chinese Glacier Inventory (CGI) during the 1960s1970s and Landsat Enhance Thematic Mapper (ETM+) images from 1999 to 2001, we investigated changes for about 7665 alpine glaciers among 11665 glaciers in seven sub-basins of the Tarim Interior River basin (TIRB). The results showed that the total glacier area was reduced by 3.3% from the

Donghui Shangguan; Shiyin Liu; Yongjian Ding; Lianfu Ding; Junli Xu; Li Jing

2009-01-01

294

Modeling the Climatic Controls and Topographic Form of Modern and Late Pleistocene Tropical Peruvian Glaciers  

Microsoft Academic Search

Glaciers in the tropical highlands are important and highly sensitive indicators of global climate change over different time scales. Simulating glacier extent from basic climatic and topographic input elucidates understanding of present glacier-climate processes, climate control over past glacial extent, and future impacts of changing climate. We apply a physically based, 2-D, glacier model to reconstruct steady-state glacier forms and

B. G. Mark; N. Stansell; J. G. Fairman; M. A. Plummer; D. T. Rodbell

2010-01-01

295

Glacier Sensitivity to Climate Change in the Monsoonal Himalaya: Past, Present, and Future  

NASA Astrophysics Data System (ADS)

Glaciers are particularly sensitive to climate change, making them vulnerable elements of the environment. Of potential concern for societies is the rapid glacier retreat of Himalayan glaciers. However, the temporally short and spatially sparse instrumental records of climate, and arguably shorter and sparser glacier records, make it extremely difficult to quantify glacier sensitivity to climatic change or to place recent glacier changes into a longer, historical context. Here we address many of these issues by quantifying the glacier-climate sensitivity in the Bhutanese Himalaya over the past 800 years using a combination of remote sensing data, paleoclimate data, glacier modeling, and glacial geochronology. Bhutan is chosen for two key reasons. First, Bhutan exemplifies an area where little data on glacier changes are available and where it is logistically difficult to obtain field-based studies, a common problem for many regions of the Himalayas. Thus the methods developed here will be directly applicable to other regions. Second, glaciers in Bhutan, just as neighboring glaciers in India, Nepal, and Southwest China, sit in the bulls-eye of high snow accumulation glaciers. Sensitivity tests using a surface energy- and mass-balance model show that high accumulation regions are extremely temperature-sensitive. Therefore, Bhutan's glaciers form a highly suitable natural laboratory to investigate glacier sensitivity and response to temperature change in the monsoonal Himalaya. In this study, we map Bhutan glacierized area and volume changes over the past forty years, and show significant changes and rapid retreat of these glaciers over this period of time. In addition, we map the former glacier extents for key glacierized regions of Bhutan, and produce a 10Be chronology for glacier fluctuations for one region. Finally, we model the glacierized changes over the past 800 years using Bhutan tree-ring temperature reconstructions as climate input. Our results show that the glacier model matches former glacier extents and present-day retreat rates well, providing some confidence in the glacier model results and utility. Importantly, we show that the glacier-length variability and recent retreat rates can be explained by temperature alone, strongly supporting the theoretical studies suggesting monsoonal glaciers are dominantly temperature sensitive. In addition, our results highlight the recent glacier retreat as anomalous in the last at least 800 years. Finally, we show that these glaciers will be extremely sensitive to continued temperature changes, and that it is highly unlikely for even significant increases in precipitation to compensate for continued climate warming.

Rupper, S.; Maurer, J.; Schaefer, J. M.; Cook, E. R.; Putnam, A. E.; Krusic, P.; Smith, R. G.

2013-12-01

296

Small Glacier Area Studies: A New Approach for Turkey  

NASA Technical Reports Server (NTRS)

Many regions of Earth have glaciers that have been neglected for study because they are small. We report on a new approach to overcome the problem of studying small glaciers, using Turkey as an example. Prior to our study, no reliable estimates of Turkish glaciers existed because of a lack of systematic mapping, difficulty in using Landsat data collected before 1982, snowpack vs. glacier ice differentiation using existing satellite data and aerial photography, the previous high cost of Landsat images, and a lack of high-resolution imagery of small Turkish glaciers. Since 2008, a large number of < 1 m satellite images have become available at no cost to the research community. In addition, Landsat data are now free of charge from the U.S. Geological Survey, enabling the use of multiple images. We used 174 Landsat and eight high-resolution satellite images to document the areal extent of Turkish glaciers from the 1970s to 2007-2011. Multiple Landsat images, primarily Thematic Mapper (TM) data from 1984 to 2011, enabled us to minimize differentiation problems between snow and glacier ice, a potential source of error. In addition, we used Ikonos, Quickbird, and World View-1 & -2 very high-resolution imagery to evaluate our TM accuracies and determine the area of nine smaller glaciers in Turkey. We also used five Landsat-3 Return Beam Videcon (RBV) 30 m pixel resolution images, all from 1980, for six glaciers. The total area of Turkish glaciers decreased from 23 km2 in the 1970s to 10.1 km2 in 2007-2011. By 2007-2011, six Turkish glaciers disappeared, four were < 0.3 km2, and only three were 1.0 km2 or larger. No trends in precipitation from 1970 to 2006 and cloud cover from 1980 to 2010 were found, while surface temperatures increased, with summer minimum temperatures showing the greatest increase. We conclude that increased surface temperatures during the summer were responsible for the 56% recession of Turkish glaciers from the 1970s to 2006-2011.

Yavasli, Dogukan D.; Tucker, Compton J.

2012-01-01

297

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

298

Detection of glacier lake using ALOS PALSAR data at Bhutan  

NASA Astrophysics Data System (ADS)

The retreat of mountain glaciers and expansion of glacial lakes are the common issue related to global warming and it sometimes causes a sudden flood, which is called as Glacier Lake Outburst Flood (GLOF). GLOF event occurs frequently in 1960s at Himalayan glaciers. Satellite data is a sophisticated tool for this research because it is difficult to operate frequent field survey due to severe weather condition and hard accessibility. However, the optical sensor equipped on satellite has one serious problem, which is weather condition of target area. It is very difficult to acquire cloud-free data at Himalayan region on a regular schedule. Therefore, it is necessary to find another way to avoid this problem. Synthetic Aperture Radar (SAR) is one possible way because SAR can observe under all weather condition and SAR image is able to distinguish water surface and other landcovers because water surface is smoother than the other landcovers, especially in the case of L-band wavelength scale. On the other hand, SAR image has geometric and radiometric distortion due to its observation mechanism and topographic feature. Geometric distortion is able to correct by applying systematic orthorectification using DEM data. However, radiometric distortion is still remained. Recently, several radiometric terrain correction (RTC) methods are proposed. This method corrects the radiometric distortion due to local topographic slope. After RTC, radiometric distortion due to topographic relief is suppressed and backscatter brightness of the image after RTC almost depend on landcovers. In this study, we used L-band ALOS/PALSAR (SAR) data after applying RTC, ALOS/AVNIR-2 (Optical Sensor) data and SRTM-3 (DEM) data. PALSAR data is used for detection of glacier lake to set threshold of radar brightness. AVNIR-2 data is used for making glacier mask area because radar brightness of smooth glacier or icecap area is as dark as water surface on the PALSAR image. To avoid this misdetection, we applied glacier mask by AVNIR-2 data. SRTM-3 data has two ways to use. One is source data for orthorectification of PALSAR data and the other is selection of candidate for glacier lake. The selection criteria for glacier lake candidate are surface slope and topographic height. Surface slope is criterion for surface flatness and topographic height is criterion for existence condition of liquid water. We used these criteria in combination for detection of glacier lakes. Preliminary consistency comparison result with ICIMODs' glacier lake inventory detected several mistakes of ICIMOD's inventory. We also have a plan to validate these glacier lake detection results with manual interpretation results of glacial lakes using optical sensor which compiled under SATREPS (Science and Technology Research Partnership for Sustainable Development) project by JICA and JST.

Yamanokuchi, T.; Tadono, T.; Tomiyama, N.

2010-12-01

299

Comparative Analysis of Glaciers in the Chugach-St.-Elias Mountains  

NASA Astrophysics Data System (ADS)

The phenomenon of glacier surges has to date been studied for only relatively few examples. 136 of the 204 surge-type glaciers in North America listed by Post (1969) are located in the St. Elias Mountains. In August 2003 we increased our data inventory of observations on surge glaciers by collecting material for 19 glaciers in the Glacier Bay area and neighboring regions in the eastern St. Elias Mountains, including 6 surge-type glaciers (Carroll, Rendu, Ferris, Grand Pacific, Margerie, and Johns Hopkins Glaciers). Analyses utilize digital video and photographic data, satellite data and GPS data. Geostatistical classification parameters and algebraic parameters characteristic of surge motions are derived for selected glaciers. During the 1993-1995 surge of Bering Glacier the entire surface of Alaska's longest glacier was crevassed and could be segmented into several dynamic provinces, where patterns changed as the surge progressed and the affected areas expanded downglacier and upglacier, finally affecting the Bagley Ice Field. The middle moraine of Grand Pacific and Ferris Glaciers is pushed over to the Grand Pacific side, caused by a recent surge of the heavily crevassed Ferris Glacier. The front of Johns Hopkins Glacier advances, as its lower reaches are affected by a surge. The surge history of Bering Glacier goes back to the Holocene, whereas Carroll and Rendu Glaciers have surged only 3-4 times. These observations pose questions on the possible relationship between surge dynamics and climatic changes.

Herzfeld, U. C.; Mayer, H.

2003-12-01

300

Snow glacier melt estimation in tropical Andean glaciers using Artificial Neural Networks  

NASA Astrophysics Data System (ADS)

Snow and glacier melt (SGM) estimation plays an important role in water resources management. Although melting process can be modelled by energy balance methods, such studies require detailed data which is rarely available. Hence, new and simpler approaches are needed for SGM estimations. Artificial Neural Networks (ANN) is a modelling paradigm able to reproduce complex non-linear processes without the need of an explicit representation. The present study aims at developing an ANN based technique for estimating SGM rates using available and easy to obtain data such as Temperature and short wave radiation. Several ANN models were developed to represent the SGM process of a tropical glacier in the Bolivian Andes. The main data consisted on short wave radiation and temperature. It was found that accuracy may be increased by considering relative humidity and melting from previous time steps. The model represents the daily pattern showing variation of the melting rates throughout the day, with highest rate at noon. The melting rate in October (1.35 mm h-1) is nearly three times higher than July's melting rate (0.50 mm h-1). Results indicate that the exposure time to melting in October is 12 h, while in July is 9 h. This new methodology allows estimation of SGM at different hours throughout the day, reflecting its daily variation which is very important for tropical glaciers where the daily variation is greater than the yearly one. This methodology will provide useful data for better understanding the glacier retreat process and for analysing future water scenarios.

Moya Quiroga, V.; Mano, A.; Asaoka, Y.; Udo, K.

2012-08-01

301

Glacier-specific elevation changes in western Alaska  

NASA Astrophysics Data System (ADS)

Deriving glacier-specific elevation changes from DEM differencing and digital glacier outlines is rather straight-forward if the required datasets are available. Calculating such changes over large regions and including glaciers selected for mass balance measurements in the field, provides a possibility to determine the representativeness of the changes observed at these glaciers for the entire region. The related comparison of DEM-derived values for these glaciers with the overall mean avoids the rather error-prone conversion of volume to mass changes (e.g. due to unknown densities) and gives unit-less correction factors for upscaling the field measurements to a larger region. However, several issues have to be carefully considered, such as proper co-registration of the two DEMs, date and accuracy of the datasets compared, as well as source data used for DEM creation and potential artefacts (e.g. voids). In this contribution we present an assessment of the representativeness of the two mass balance glaciers Gulkana and Wolverine for the overall changes of nearly 3200 glaciers in western Alaska over a ca. 50-year time period. We use an elevation change dataset from a study by Berthier et al. (2010) that was derived from the USGS DEM of the 1960s (NED) and a more recent DEM derived from SPOT5 data for the SPIRIT project. Additionally, the ASTER GDEM was used as a more recent DEM. Historic glacier outlines were taken from the USGS digital line graph (DLG) dataset, corrected with the digital raster graph (DRG) maps from USGS. Mean glacier specific elevation changes were derived based on drainage divides from a recently created inventory. Land-terminating, lake-calving and tidewater glaciers were marked in the attribute table to determine their changes separately. We also investigated the impact of handling potential DEM artifacts in three different ways and compared elevation changes with altitude. The mean elevation changes of Gulkana and Wolverine glaciers (about -0.65 m / year) are very similar to the mean of the lake-calving and tidewater glaciers (about -0.6 m / year), but much more negative than for the land-terminating glaciers (about -0.24 m / year). The two mass balance glaciers are thus well representative for the entire region, but not for their own class. The different ways of considering positive elevation changes (e.g. setting them to zero or no data) influence the total values, but has otherwise little impact on the results (e.g. the correction factors are similar). The massive elevation loss of Columbia Glacier (-2.8 m / year) is exceptional and strongly influences the statistics when area-weighting is used to determine the regional mean. For the entire region this method yields more negative values for land-terminating and tidewater glaciers than the arithmetically averaged values, but for the lake-calving glaciers both are about the same.

Paul, Frank; Le Bris, Raymond

2013-04-01

302

Glacier mass balance of tropical Zongo glacier, Bolivia, comparing hydrological and glaciological methods  

NASA Astrophysics Data System (ADS)

A glaciological program has been undertaken since 1991 on Zongo glacier in Bolivia (6000-4850 m asl, 2.4 km 2, 16S). This program involves mass balance measurements, hydrological studies and energy balance investigations. On outer-tropical glaciers, melting and snow accumulation are both maximum in the wet season (austral summer), whereas the dry season (winter) is a period of low ablation. Errors on each term of the glaciological (stakes, snow-pits and integration method of the measurements) and hydrological (precipitation, discharge and runoff coefficient of free ice areas) methods are investigated to estimate the overall accuracy of the mass balance measurements. The hydrological budget is less than the glaciological one (mean difference: 60 cm w.e. per year), but both methods reproduce similar inter-annual variations. Errors in assessment of evaporation or water storage inside the glacier cannot explain the discrepancy. Errors using the glaciological method are large (around 40 cm w.e. per year), but no bias can explain the departure from the hydrological balance. Errors on discharge measurements are small and the uncertainty on the runoff coefficient has a minor effect on the mass balance. We concluded that hydrological budgets are too low due to the catch deficiency of rain gauges and absence of precipitation measurements at high altitudes, emphasizing the difficulty to assess snowfall distribution in high mountainous basins.

Sicart, Jean Emmanuel; Ribstein, Pierre; Francou, Bernard; Pouyaud, Bernard; Condom, Thomas

2007-10-01

303

Irreversible mass loss from Canadian Arctic glaciers  

NASA Astrophysics Data System (ADS)

The Canadian Arctic Archipelago (CAA) contains the largest volume of glacier ice outside Greenland and Antarctica, equivalent to 0.220.03 m eustatic sea level. In the absence of significant solid ice discharge (D~5 Gt yr-1), CAA mass balance is largely dominated by surface mass balance (SMB), the difference between snow accumulation and meltwater runoff. Results from the Gravity Recovery and Climate Experiment (GRACE) satellites show that, following a recent atmospheric warming (1-2 K), CAA mass loss increased from 318 Gt yr-1 in 2004-2006 to 9212 Gt yr-1 in the period 2007-2009. As yet, it has been unclear if this sharp increase in mass loss can be attributed to natural variability on decadal time scales, or that it marks the onset of a long-term warming and consequent CAA mass loss. In this study we use a high-resolution regional atmospheric climate model (RACMO2), coupled with a sophisticated snow/firn/ice column physics model, driven by ERA-reanalyses (1960-2011) to assess past and present-day CAA mass balance. Since we neglect D in the mass balance, mass anomalies can be attributed to SMB only, which enables direct comparison between RACMO2 and GRACE (RL04). In the period 2004-2011, CAA lost ice at a rate of 6410 Gt yr-1 according to RACMO2, which agrees with GRACE (726 Gt yr-1). The longer temporal coverage of the RACMO2 results enables us to put the recent mass loss in a longer-term perspective. RACMO2 suggests that NCAA was in approximate mass balance before the year 2000, whereas the Southern CAA (SCAA) also lost mass in 1960-2000 at a rate of 1511 Gt yr-1, a finding that agrees with recent estimates from altimetry and stereographic imaginery (-114 Gt yr-1 in 1963-2006). To assess CAA mass loss for the remainder of the 21st century, RACMO2 was forced at the lateral boundaries by HadGEM2-ES, a fully coupled CMIP5 general circulation model (GCM). This GCM in turn was forced with the modest warming scenario RCP45, resulting in a 21st century warming that is similar to the average of all AR5 scenarios. Mean CAA glacier SMB decreases to -14433 Gt yr-1, and mass loss is then larger in NCAA (8231 Gt yr-1) than in SCAA (6210 Gt yr-1). Mass loss is dominated by meltwater runoff, only partially (~30%) compensated by increasing precipitation. We apply the significant correlation between CAA SMB and CAA T2m to all AR5 multi-model realizations (~6500 single years) and found out this estimate is relatively conservative. More importantly, CAA glacier growth (SMB>0) is predicted in only 0.15% of the ensemble members, rendering it highly unlikely that current CAA glacier mass loss will be reversed. Based on the full AR5 ensemble, we estimate the total CAA mass loss at 124008500 Gt yr-1 until 2100, equivalent to 0.350.24 mm yr-1. This makes CAA the largest cryospheric contributor to 21st century sea level rise outside Greenland and Antarctica.

Lenaerts, J.; van Angelen, J.; van den Broeke, M. R.; Gardner, A. S.; Wouters, B.; van Meijgaard, E.

2012-12-01

304

Melting glaciers can change Earth's gravity field  

NASA Astrophysics Data System (ADS)

The Earth's rotation causes mass from the ductile mantle to bulge at the equator, making the radius of the Earth about 21 kilometers greater at the equator than at the poles. Over the past 20,000 or so years, the Earth has been becoming more round as it adjusts to the withdrawal of vast continental glaciers after the last ice age: Without the weight of ice pressing down, land has rebounded to give the Earth a more spherical shape. This in turn means that the Earth|'s geoidthe average gravity field across the globealso became more round. However, in the early 1990s, scientists began to notice that postglacial rebound was starting to become offset by something else, causing the Earth's gravity field to cease changing shape.

Kumar, Mohi

2011-09-01

305

Glaciers and ice sheets as a biome.  

PubMed

The tundra is the coldest biome described in typical geography and biology textbooks. Within the cryosphere, there are large expanses of ice in the Antarctic, Arctic and alpine regions that are not regarded as being part of any biome. During the summer, there is significant melt on the surface of glaciers, ice caps and ice shelves, at which point microbial communities become active and play an important role in the cycling of carbon and other elements within the cryosphere. In this review, we suggest that it is time to recognise the cryosphere as one of the biomes of Earth. The cryospheric biome encompasses extreme environments and is typified by truncated food webs dominated by viruses, bacteria, protozoa and algae with distinct biogeographical structures. PMID:22000675

Anesio, Alexandre M; Laybourn-Parry, Johanna

2012-04-01

306

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

307

(abstract) A Mini-Surge on the Ryder Glacier, Greenland  

NASA Technical Reports Server (NTRS)

We have detected a dramatic short-term speedup of the Ryder Glacier, Greenland, using satellite radar interferometry. The accelerated flow represents a substantial, though short-lived, change in the ice discharge from the basin. We use the term.

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

1996-01-01

308

100 Years of Glacier Retreat in Central Asia  

E-print Network

Glacier stagnation and lake formation in Bhutan (ASTER, Nov. 30, 2001)lake formation in Bhutan (ASTER, Nov. 30, 2001) #12;Himalayas Bhutan A. Kääb / University of Zurich #12;Himalayas Bhutan A. Kääb / University

309

The Role of Glaciers in the Hydrology of Nepal (Invited)  

NASA Astrophysics Data System (ADS)

Glaciers are a component of the hydrologic regime of many large mountain ranges of the world, including the Himalaya. However, the hydrologic regime of Himalayan catchment basins and the role of glaciers in the hydrologic regime of this region are not well understood. Current concern regarding the impact of the retreat of Himalayan glaciers on water supplies poses an urgent need to resolve basic questions related to the components of the total water budget and, specifically, to determine the impact of glacier change on regional-scale water supplies. The ultimate goal of this project is to estimate the potential impact of continued glacier retreat across the entire Himalayan region, although the results presented here are limited to assessing and quantifying the role of glacier ice melt in the hydrologic regime of Nepal. There are approximately 3250 glaciers in the Nepal Himalaya, covering an area of slightly more than 5,300 km2, and containing some 460 km3 of ice. These glaciers are located on, or near, the crest of the Himalaya, with the bulk of the ice contained in basins that are at altitudes generally between 4,000 - 6000 meters above sea level. The methodology developed for this study involves establishing a relationship between the area-altitude distributions of catchment basins and glaciers, and associated water and energy exchange gradients. Two area-altitude distributed process models were developed: an orographic runoff model and a glacier melt model. The orographic runoff model is based on the relationship between basin mean specific runoff and the mean altitude of each basin with an area-altitude distribution of streamflow for each 1000 meter belt calculated as the product of the specific runoff depth and the area of the belt. The glacier melt model is based on melt from 100 meter area-altitude belts for the glacierized portion of each catchment and involves defining an ablation gradient, the rate of increasing specific ice melt with decreasing altitude in the ablation zone. Results indicate that the annual contribution of glacier melt water to streamflow in the Nepal Himalayas varies among catchment basins from 2 to 30%, averaging approximately 10% of the total annual flow volume measured at lower altitude hydrometric stations. This represents approximately 4% of the total annual streamflow volume of the rivers of Nepal. Results also suggest that neither the timing nor the volume of the streamflow of the rivers of Nepal will be significantly affected in the near future by a continued retreat of the glaciers. We are currently applying a similar methodology to assess the contribution of glacier and snow melt to the hydrology of the upper Indus Basin located at the extreme western end of the Greater Himalaya with a climate and glacier regime that differs significantly from that of Nepal. Preliminary results from the Indus study will also be presented.

Armstrong, R. L.; Racoviteanu, A.; Alford, D.

2010-12-01

310

Accumulation of anthropogenic radionuclides in cryoconites on Alpine glaciers.  

PubMed

Cryoconites are airborne sediments which accumulate on the surface of glaciers. In samples of cryoconites a temperate Austrian glacier high activity concentrations of anthropogenic radionuclides were found, which stem from global and Chernobyl fallouts. Radionuclides identified were (137)Cs, (134)Cs, (238)Pu, (239+240)Pu, (90)Sr, (241)Am, (60)Co, (154)Eu, (207)Bi, and (125)Sb. Given the approximately known isotopic ratios, Cs and Pu can be separated into the contributions of either source of origin. Published (137)Cs/(134)Cs and (239+240)Pu/(238)Pu ratios were used for the discrimination of the Dachstein-glacier cryoconites according to their origin from global or Chernobyl fallout. Two different groups of cryoconites were identified, an older population dominated by nuclear weapons fallout and a younger one with predominant Chernobyl fallout. With those data a simple model was formulated to demonstrate the transition and mixing of these two populations on the glacier surface. PMID:19450909

Tieber, A; Lettner, H; Bossew, P; Hubmer, A; Sattler, B; Hofmann, W

2009-07-01

311

Complex and shifting Himalayan glacier changes point to complex  

E-print Network

that are thinning but have stably positioned termini - A surging glacier -- Total Himalayan mass balance snow accumulation (snowfall and any added snow avalanches) is balanced by melting and sublimation

312

Hydrology and Glaciers in the Upper Indus Basin  

E-print Network

Examines the state of the science associated with the snow and ice hydrology in the Upper Indus Basin (IUB), reviewing the literature and data available on the present and projected role of glaciers, snow fields, and stream ...

Yu, Winston

313

Glacier changes since the Little Ice Age maximum in the western Qilian Shan, northwest China, and consequences of glacier runoff for water supply  

Microsoft Academic Search

Based on aerial photographs, topographical maps and the Landsat-5 image data, we have analyzed fluctuations of glaciers in the western Qilian Shan, northwest China, from the Little Ice Age (LIA) to 1990. The areas and volumes of glaciers in the whole considered region decreased 15% and 18%, respectively, from the LIA maximum to 1956.This trend of glacier shrinkage continued and

Liu Shiyin; Sun Wenxin; Shen Yongping; Li Gang

2003-01-01

314

A theoretical approach to glacier equilibrium-line altitudes using meteorological data and glacier mass-balance records from southern Norway  

Microsoft Academic Search

Based on a close exponential relationship between mean ablation-season temperature and winter precipitation at the equilibrium-line altitude (ELA) of 10 Norwegian glaciers, three equations are derived. The first equation enables calculation of the minimum altitude of areas climatically suited for glacier formation, and is termed the altitude of instantaneous glacierization (AIG). Equation (2) is derived based on the principle of

yvind Lie; Svein Olaf Dahl; Atle Nesje

2003-01-01

315

Glacier elevation changes on the Tibetan Plateau derived by ICESat  

NASA Astrophysics Data System (ADS)

Glaciers are a sensitive indicator for climate change in high mountain regions where climate stations are rare or non-existent. In addition, glacier changes have a significant impact on the hydrological cycle of the vulnerable region of the Tibetan Plateau. Therefore a continuous monitoring of glaciers is necessary. In-situ measurements are essential but can only be conducted at a very limited number of glaciers in this large and remote region due to enormous logistical efforts and high costs. Remote sensing techniques are suitable to complement these in-situ measurements and address a large area simultaneously. Traditionally, mountain glaciers are monitored in terms of area changes from aerial or satellite image data. However, these changes show, in contrast to volume changes, a delayed signal to climate only. In order to estimate volume changes of glaciers on the Tibetan Plateau data from the Geoscience Laser Altimeter System (GLAS) carried on-board the Ice Cloud and Elevation Satellite (ICESat) was used for extraction of elevation changes for the period 2003 to 2009. GLAS shots over glaciers were selected using the Global Land Ice Measurements from Space (GLIMS) dataset with support of recent cloud free Landsat scenes obtained from USGS. ICESat repeat-tracks are spatially close but do not match exactly. They can be horizontally separated by up to 3000 m. Therefore, an independent reference surface is used for a multi-temporal comparison of GLAS shots. For this purpose we use a Digital Elevation Model (DEM) acquired in February 2000 by the Shuttle Radar Topography Mission (SRTM). Glaciers with an adequate ICESat data coverage (approximately 12% of the glaciers captured in the GLIMS database) were grouped according to the mountain chains in certain compact geographic regions. Mean trends in glacier elevation changes were estimated for these regions for the seven years of ICESat's lifetime. Preliminary results suggest a heterogeneous wastage of glaciers across the Tibetan Plateau with higher melting rates in the East, (e.g. Nyainqentanglha Mountains) and lower ones in the West (e.g. Kunlun Shan).

Neckel, N.; Kropacek, J.; Bolch, T.

2012-04-01

316

From Glacier Facies to SAR Backscatter Zones via GPR  

Microsoft Academic Search

We present a comparison between data acquired with frequency-modulated ground-penetrating radar (GPR) and satellite synthetic aperture radar (SAR). Both radars are polarimetric and operate at a center frequency of 5.3 GHz. The field site is the polythermal glacier Kongsvegen, Svalbard. Along glacier GPR profiles cover the ablation area and the accumulation area, where the latter consists of superimposed ice (SI)

Kirsty Langley; Svein-Erik Hamran; Kjell Arild Hogda; Rune Storvold; Ola Brandt; Jack Kohler; Jon Ove Hagen

2008-01-01

317

Pine Island Glacier - basal properties and sliding laws  

NASA Astrophysics Data System (ADS)

The dynamics of the Antarctic Ice Sheet can be well seen and studied on the behavior of Pine Island Glacier. Despite the long time believe in a slow response of the ice sheet to changing atmospheric and oceanic forcing, Pine Island has shown acceleration, thinning and a significant grounding line retreat in the past decades. These ongoing processes are coinciding with a concentrated mass loss in the area around Pine Island Glacier, the Amundsen Sea Embayment. The area is of additional interest due to its retrograde bed slope below the glacier. The postulated instability of the setting turns the glacier into an even more suitable object for modeling studies. Plenty of working groups have conducted modeling studies of Pine Island Glacier with varying model complexity and diverse focuses. We want to add to this by conducting model experiments with a diagnostic 3D full-stokes model of Pine Island Glacier. The model is thermo-mechanically coupled and implemented with the commercial finite-element package COMSOL Multiphysics. We use remotely sensed surface velocity data to validate our results. The focus of our work lies on the basal properties below the glacier and the connection to sliding behavior. We believe that this is a crucial part, as different basal conditions might cause different responses to ongoing changes in the area. Recent studies presented evidence for the existence of a water saturated sediment basin below the main trunk of the glacier. We conduct a variety a numerical experiments with which we test different approaches of combining information about the basal properties with sliding laws.

Wilkens, Nina; Humbert, Angelika

2013-04-01

318

Impacts of Yulong Mountain glacier on tourism in Lijiang  

Microsoft Academic Search

The glacier on the Yulong Mountain is one of the most important attractions in Lijiang, Yunnan, China. But it keeps retreating\\u000a these years due to global warming, which is bound to influence regional tourism significantly in Lijiang. This study estimates\\u000a the effects of the glacier retreat of the Yulong Mountains on tourism there. Primary data were collected through a visitor

Lingling Yuan; Aigang Lu; Baoying Ning; Yuanqing He

2006-01-01

319

Characteristics of the bed of the lower Columbia Glacier, Alaska  

Microsoft Academic Search

Results are presented on borehole measurements of the strength of deforming subglacial till under the central region of the Columbia Glacier in southeastern Alaska. Data on the basal samples, coring, and down-hole water samples show that the fiord-filling lower reach of the glacier is underlain by a thin (about 7-cm) veneer of rock debris. Samples from a higher site showed

Neil Humphrey; Barclay Kamb; Mark Fahnestock; Hermann Engelhardt

1993-01-01

320

Is Glacier wastage continuing to accelerate in NW North America?  

NASA Astrophysics Data System (ADS)

Laser altimetry elevation profiles of glaciers have been collected in Alaska, Yukon, and NW British Columbia (herein NW North America) by the University of Alaska Geophysical Institute beginning in 1993. Since that time, over 27,000 km of glacier profiles have been acquired. Nearly 200 glaciers throughout NW North America have been measured, many of them multiple times. All of the largest glaciers in NW North America have been profiled, including at least some representative glaciers from every major icefield in NW North America. This dataset includes a broad range of glacier sizes distributed across the region. Several glacier and icefield regions within Alaska and adjoining Canada have been profiled multiple times at this stage, and data from these regions are being analyzed for changes in the rates of thinning. Specific regions include Harding Icefield, the central Alaska Range, Yakutat Icefield, Glacier Bay, and Juneau Icefield. Hypsometry appears to be a significant factor, with those areas that have relatively low elevation accumulation areas showing signs of accelerated thinning, particularly the Harding and Yakutat Icefields. Other areas that have relatively high elevation accumulation areas appear to have steady rates of thinning, such as within the St. Elias Mountains. The profile ground tracks have all been converted into files that can be displayed in Google Earth, and are available for easy download from our webpage (http://fairweather.gps.alaska.edu/chris). In order to allow for open distribution to the community, all of the profile elevation data are being reprocessed into a common reference frame (ITRF), which not only allows for accurate inter-comparison of repeated laser altimetry data but also will allow for comparison with other elevation datasets, such as digital elevation models derived from satellite remote sensing.

Larsen, C. F.; Echelmeyer, K. A.; Harrison, W. D.; Arendt, A. A.; Lingle, C. S.

2008-12-01

321

Glacier Fluctuations in the Nanga Parbat Region of Western Himalaya  

NASA Astrophysics Data System (ADS)

Glaciers in many mountain environments have shown general retreat patterns, most likely due to atmospheric warming. Glaciers in the Western Himalaya are perhaps more complicated than other regions due to their complex topography, extensive supraglacial debris cover, and climate-system coupling involving the westerlies and the monsoon. Consequently, our objectives were to assess glacier fluctuations in the Nanga Parbat Himalaya as a part of the International Global Land Ice Measurements from Space (GLIMS) project. Specifically, we conducted change-detection studies to estimate fluctuation rates. A high-quality topographic map from 1934, Keyhole imagery from the 1970s, SPOT images from 1990 and 2005, and ASTER satellite imagery from 2004 were utilized to identify terminus positions, and triangulation methods were used to account for variations in terminus shape and orientation. Our results indicate that some glaciers are retreating and/or maintaining their frontal position while others have advanced at different time periods. Some of these glaciers have also shown downwasting characteristics in the form of increased frequency and size of supraglacial lakes. Average retreat rates, however, are not nearly as large as those reported in India, the Eastern Himalaya, and the Hindu Kush region. Glacier advances in this region have neither been reported as surge-type glaciers in the past, nor have any shown surge-type patterns; therefore, these advances may be due to positive mass balance. Analysis of climate reanalysis data (ERA40) suggest an increase in precipitation in the region. Nanga Parbat glaciers appear to be oscillating, although a recent retreat pattern can be found. There is an urgent need for regional climate and surface energy-budget modeling to assess these complexities to determine the nature of these oscillations.

Haritashya, U. K.; Bishop, M. P.; Shroder, J. F.

2008-12-01

322

Historic Glacier Change using a GIS: Progress and problems  

NASA Astrophysics Data System (ADS)

We are exploring the potential wealth of information on glacier extent and topography contained in historic maps. If successful, we can examine the spatial and temporal patterns of historic glacier change where glaciological studies are typically absent. Our project is focused on the American West and data on glacier extent and topography is derived from aerial and ground-based photographs, paper maps, and digital maps. Our initial conception was that digital maps would provide a reliable base on which new data can be added. However, we encountered many errors when compiling the glacier outlines from the 100K scale USGS digital line graph (DLG) coverage. We resorted to overlaying the DLG coverage over the scanned and geo-registered paper maps (digital raster graphics) to error check the DLG coverage. At the time of this writing we are working on the 24K scale coverage, which we obtained from the US Forest Service that uses a different approach to digital map presentation. One important challenge is to define the date of the mapping. Because glaciers change in time, we need to know the date of photography used to make the USGS map. However the data accompanying the maps do not specify what part of the map was updated at the time of last printing. Experience shows that the glacier features are not updated and their outline dates to the original photography from which the first map was made. Although our immediate goal is to assess changes in area, changes in volume are important as well. We found that that historic evaluations of topography (prior to aerial photography) appear reasonable low on glaciers in the ablation zone, higher on the glaciers the topography can be way off and suggests caution in relying on such data sources. While we have found fairly good results in using historic maps, one must carefully examine every map to evaluate its reliability.

Granshaw, F.; Fountain, A. G.; Percy, D.; Ebnet, A.

2004-12-01

323

Assemblages of submarine landforms produced by tidewater glaciers in Svalbard  

NASA Astrophysics Data System (ADS)

High-resolution swath bathymetry from the marine margins of several Svalbard tidewater glaciers shows an assemblage of submarine landforms that is probably linked to glacier surging. These landforms are essentially unmodified since their initial deposition over the past hundred years or so because they have not been subjected to subaerial erosion or periglacial activity. Swath images comprise an assemblage of superimposed landforms, allowing reconstruction of relative age of deposition: (1) large transverse ridges, interpreted as recessional moraines overridden by a subsequent ice advance; (2) a series of curvilinear streamlined bedforms orientated parallel to former ice flow, interpreted as lineations formed subglacially during rapid advance; (3) large terminal ridges, marking the farthest extent of ice at the last advance, with flow lobes immediately beyond interpreted as submarine debris flows; (4) a series of interconnected rhombohedral ridges, interpreted as a product of soft sediment squeezing into crevasses formed at the glacier bed, probably formed during immediate post-surge stagnation; and (5) a series of fairly evenly spaced small transverse ridges, interpreted as push moraines produced annually at tidewater glacier termini during retreat. A simple descriptive landsystem model for tidewater glaciers of probable surge type is derived from these observations. We also show that megascale glacial lineations can form not only beneath large ice streams, but are also produced beneath surging tidewater glaciers lying on deforming sedimentary beds.

Ottesen, D.; Dowdeswell, J. A.

2006-03-01

324

Rapdily recurring Jkulhlaups from Koppangsbreen glacier, Northern Norway  

NASA Astrophysics Data System (ADS)

A jkulhlaup (Glacier Lake Outburst Flood) from a glacier-dammed lake at the glacier Koppangsbreen in northern Norway occurred on 4th June 2013. Approximately two million cubic metres of water were released from the lake over eleven hours, and reached the village of Koppangen down-valley only minutes later. This was followed by another six events over the next thirty days, at intervals of three to ten days. Previous events had occurred from this glacier in the three preceding years, but only one event in each of 2010 and 2011, and two small events in 2012. Thus, the short intervals between each flood in 2013 were unprecedented. Some of the events were connected to rainfall but not all of them, thus this wasn't the only trigger. The almost periodic nature of the events also argues against tunnel collapse and re-opening initiating a new event. However, by considering the input to the lake from a combination of precipitation, snow melt and, as the season progressed, glacier melt, it is shown that in just a few days the lake level increases enough for the water to escape under the glacier.

Jackson, Miriam

2014-05-01

325

A precise monitoring of snow surface height in the region of Lambert Glacier basin-Amery Ice Shelf, East Antarctica  

Microsoft Academic Search

The net surface snow accumulation on the Antarctic ice sheet is determined by a combination of precipitation, sublimation\\u000a and wind redistribution. We present a one-year record of hourly snow-height measurements at LGB69 (7050?S, 77?04?E, 1850\\u000a m a.s.l.), east side of Lambert Glacier basin (LGB), and 4 year record at G3 (70?53?S, 69?52?E, 84 m a.s.l.), Amery Ice Shelf\\u000a (AIS). The

Cunde Xiao; Dahe Qin; Lingen Bian; Xiuji Zhou; I. Allison; Ming Yan

2005-01-01

326

The relevance of glacier melt in the water cycle of the Alps: the example of Austria  

NASA Astrophysics Data System (ADS)

This paper quantifies the contribution of glacier melt to river runoff from compilation and statistical interpretation of data from available studies based on observations or glacio- hydrological modelling for the region of Austria (Austrian Salzach and Inn river basin). A logarithmic fit between the glacier melt contribution and the relative glacierized area was found not only for the long-term mean glacier contributions but also for the glacier melt contribution during the extreme hot an dry summer of 2003. Interestingly, the mean contributions of glacier melt to river runoff do not exceed 15 % for both river catchments and are uncorrelated to glacierization for glacierization values >10 %. This finding, however, has to be seen in the light of the general precipitation increase with altitude for the study region which levels out the increase of absolute melt with glacierization thus resulting in the rather constant value of glacier melt contribution. In order to qualitatively proof this finding another approach has been applied by calculating the quotient qA03 of the mean monthly August runoff in 2003 and the long-term mean August runoff for 38 gauging stations in Austria. The extreme summer 2003 was worth to be analysed as from the meteorological and glaciological point of view an extraordinary situation was observed. During June and July nearly the entire snow-cover melted and during August mainly bare ice melt of glaciers contributed to runoff. The qA03 quotients were calculated between 0.32 for a non-glacierized and 2.0 for a highly glacierized catchment. Using the results of this study the mean and maximum possible glacier melt contribution of catchments can be estimated based on the relative glacierized area. It can also be shown that the found correlation of glacierized area and glacier melt contribution is applicable for the Drau basin where yet no results of modelled glacier melt contributions are available.

Koboltschnig, G. R.; Schner, W.

2011-06-01

327

Glacier changes in the Karakoram region mapped by multimission satellite imagery  

NASA Astrophysics Data System (ADS)

Positive glacier-mass balances in the Karakoram region during the last decade have fostered stable and advancing glacier termini positions, while glaciers in the adjacent mountain ranges have been affected by glacier recession and thinning. In addition to fluctuations induced solely by climate, the Karakoram is known for a large number of surge-type glaciers. The present study provides an updated and extended inventory on advancing, stable, retreating, and surge-type glaciers using Landsat imagery from 1976 to 2012. Out of 1219 glaciers the vast majority showed a stable terminus (969) during the observation period. Sixty-five glaciers advanced, 93 glaciers retreated, and 101 surge-type glaciers were identified, of which 10 are new observations. The dimensional and topographic characteristics of each glacier class were calculated and analyzed. Ninety percent of nonsurge-type glaciers are shorter than 10 km, whereas surge-type glaciers are, in general, longer. We report short response times of glaciers in the Karakoram and suggest a shift from negative to balanced/positive mass budgets in the 1980s or 1990s. Additionally, we present glacier surface velocities derived from different SAR (synthetic aperture radar) sensors and different years for a Karakoram-wide coverage. High-resolution SAR data enables the investigation of small and relatively fast-flowing glaciers (e.g., up to 1.8 m day-1 during an active phase of a surge). The combination of multitemporal optical imagery and SAR-based surface velocities enables an improved, Karakoram-wide glacier inventory and hence, provides relevant new observational information on the current state of glaciers in the Karakoram.

Rankl, M.; Kienholz, C.; Braun, M.

2014-05-01

328

Reconstructing glacier retreat since the Little Ice Age in SE Tibet by glacier mapping and equilibrium line altitude calculation  

NASA Astrophysics Data System (ADS)

Temperate glaciers in the eastern Nyainqntanglha Range, southeastern Tibet, are highly sensitive to climate change and therefore of particular high interest for research on late Holocene changes of the monsoonal climate in High Asia. However, because of the remoteness of the area, the scarcity of empirical data, and the challenges to remote sensing work posed by cloud and snow cover, knowledge about the glacier dynamics and changes in this region is still very limited. In this study, we applied a remote sensing approach in which 1964 glaciers were mapped from a Landsat ETM+ scene and subsequently parameterized by DEM-supported measurements. Geomorphological evidence, i.e., trimlines and latero-frontal moraines, were used to obtain quantitative data on the glaciers' morphological characteristics and the changes since the Little Ice Age (LIA) maximum glacier advance. Statistical analysis of glacier length change revealed an average retreat of ~ 27% and a trend toward stronger retreat for smaller glaciers. An evaluation of different methods to calculate equilibrium line altitudes (ELAs) indicates that an optimized toe-to-ridge altitude method (TRAM) is more suitable than other methods in settings with complex topography and a lack of mass balance measurements. A large number of glacier measurements are crucial for high quality of TRAM results, and special attention has to be paid to different glacier characteristics. In order to determine the best-fitting TRAM ratio value and to test the quality of the calculated ELAs, a remote sensing approach was applied: for each investigated glacier, the altitudes of transient snowlines visible in the late summer Landsat scene were measured from the DEM and compared to TRAM results. The interpolated ELA results show a SE-NW gradient ranging from 4400 to 5600 m asl and an average ELA rise of ~ 136 m since the LIA. Because of the high spatial resolution of measurements, the ELA distribution reveals topographic effects down to the catchment scale, specifically orographic rainfall and leeward shielding. The interpretation of these patterns reveals that the eastern Nyainqntanglha Range is influenced by both, the Indian (ISM) and East Asian summer monsoon (EASM). However, the EASM does not reach the western part of the study area. The results indicate that the monsoonal temperate glaciers' high sensitivity to climate change is driven by two double forcings owing to the coincidence of accumulation and ablation phases.

Loibl, David; Lehmkuhl, Frank; Grieinger, Jussi

2014-06-01

329

36 CFR 13.1134 - Who is eligible for a Glacier Bay commercial fishing lifetime access permit?  

Code of Federal Regulations, 2011 CFR

... Who is eligible for a Glacier Bay commercial fishing lifetime access permit...Regulations-Glacier Bay National Park and Preserve Commercial Fishing 13.1134 Who is eligible for a Glacier Bay commercial fishing lifetime access permit?...

2011-07-01

330

36 CFR 13.1134 - Who is eligible for a Glacier Bay commercial fishing lifetime access permit?  

Code of Federal Regulations, 2010 CFR

... Who is eligible for a Glacier Bay commercial fishing lifetime access permit...Regulations-Glacier Bay National Park and Preserve Commercial Fishing 13.1134 Who is eligible for a Glacier Bay commercial fishing lifetime access permit?...

2010-07-01

331

36 CFR 13.1134 - Who is eligible for a Glacier Bay commercial fishing lifetime access permit?  

Code of Federal Regulations, 2012 CFR

... Who is eligible for a Glacier Bay commercial fishing lifetime access permit...Regulations-Glacier Bay National Park and Preserve Commercial Fishing 13.1134 Who is eligible for a Glacier Bay commercial fishing lifetime access permit?...

2012-07-01

332

36 CFR 13.1134 - Who is eligible for a Glacier Bay commercial fishing lifetime access permit?  

Code of Federal Regulations, 2013 CFR

... Who is eligible for a Glacier Bay commercial fishing lifetime access permit...Regulations-Glacier Bay National Park and Preserve Commercial Fishing 13.1134 Who is eligible for a Glacier Bay commercial fishing lifetime access permit?...

2013-07-01

333

High-Resolution Monitoring of Glacier Dynamics During Calving Events at Helheim Glacier South-East Greenland  

NASA Astrophysics Data System (ADS)

By bringing together expertise in glaciology, GNSS (Global Navigation Satellite System) technology and processing, and wireless networks we have designed, installed and operated a wireless network of GNSS sensors very close to the margin of the heavily crevassed and fast-flowing Helheim Glacier in south-east Greenland. In 2012, we undertook field trials installing 3 GNSS sensors on the glacier's flowline, and observed the dynamic effects of a major calving event. In 2013, a full 20 node wireless network was installed together with 5 oblique cameras, instrumenting an area ~16 km^2 of the glacier margin. The network will run throughout the summer months. In combination with auxiliary data, such as airborne lidar measurement of surface topography, crevasse spacing and calving rates, oblique photogrammetry, and DEMs and velocity fields from TanDEM-X satellite imagery, the network provides velocity and elevation data of unprecedented resolution in time and space for the key marginal area of the glacier, where recent changes in glacier dynamics appear to have initiated. We present data showing the glacier's dynamic and topographic response to calving events. These data will provide rich opportunities for testing calving models and to improve understanding of the controls on the contribution of these tidewater glaciers to sea-level rise. The network has low energy consumption and a novel base-station topology providing diversity and redundancy: it is also robust to the loss of nodes as the glacier calves. Such a network would also be suitable for data collection in a number of harsh environmental settings such as earthquake, landslide or volcano monitoring.

Murray, T.; Rutt, I. C.; O'Farrell, T.; Edwards, S.; Selmes, N.; Martin, I.; James, T.; Aspey, R.; Bevan, S. L.; Loskot, P.; Baug, T.

2013-12-01

334

Quiescent-phase evolution of a surge-type glacier: Black Rapids Glacier, Alaska, U.S.A.  

USGS Publications Warehouse

Black Rapids Glacier, a surge-type glacier in the Alaska Range, most recently surged in 1936-37 and is currently in its quiescent phase. Mass balance, ice velocity and thickness change have been measured at three to ten sites from 1972 to 1994. The annual speed has undergone cyclical fluctuations of as much as 45% about the mean speed. Ice thickness and surface slope did not change enough to cause the speed fluctuations through changes in ice deformation, which indicates that they are being driven by changes in basal motion. The behavior of Black Rapids Glacier during this quiescent phase is significantly different from that of Variegated Glacier, another well-studied surge-type glacier in Alaska. The present medial-moraine configuration of Black Rapids Glacier indicates that a surge could occur at any time. However, ice velocity data indicate that the next surge may not be imminent. We believe that there is little chance that the next surge will cross and dam the Delta River.

Heinrichs, T. A.; Mayo, L. R.; Echelmeyer, K. A.; Harrison, W. D.

1996-01-01

335

Meteorological drivers of ablation processes on a cold glacier in the semi-arid Andes of Chile  

NASA Astrophysics Data System (ADS)

Meteorological and surface change measurements collected during a 2.5 yr period are used to calculate surface mass and energy balances at 5324 m a.s.l. on Guanaco Glacier, a cold-based glacier in the semi-arid Andes of Chile. Meteorological conditions are marked by extremely low vapour pressures (annual mean of 1.1 hPa), strong winds (annual mean of 10 m s-1), shortwave radiation receipt persistently close to the theoretical site maximum during cloud-free days (mean annual 295 W m-2; summer hourly maximum 1354 W m-2) and low precipitation rates (mean annual 45 mm w.e.). Snowfall occurs sporadically throughout the year and is related to frontal events in the winter and convective storms during the summer months. Net shortwave radiation provides the greatest source of energy to the glacier surface, and net longwave radiation dominates energy losses. The turbulent latent heat flux is always negative, which means that the surface is always losing mass via sublimation, which is the main form of ablation at the site. Sublimation rates are most strongly correlated with net shortwave radiation, incoming shortwave radiation, albedo and vapour pressure. Low glacier surface temperatures restrict melting for much of the period, however episodic melting occurs during the austral summer, when warm, humid, calm and high pressure conditions restrict sublimation and make more energy available for melting. Low accumulation (131 mm w.e. over the period) and relatively high ablation (1435 mm w.e.) means that mass change over the period was negative (-1304 mm w.e.), which continued the negative trend recorded in the region over the last few decades.

MacDonell, S.; Kinnard, C.; Mlg, T.; Nicholson, L.; Abermann, J.

2013-09-01

336

Monitoring of Rock Glacier ueres Hochebenkar (Austria): an Overview  

NASA Astrophysics Data System (ADS)

Past and current interdisciplinary research at the rock glacier at ueres Hochebenkar in the tztal Alps are presented. Hochebenkar rock glacier (HK) is one of the most intensely studied rock glaciers in Austria with flow velocity measurements starting in the late 1930s. The current monitoring comprises measurements of surface flow, surface and subsurface temperature, local meteorology, runoff as well as water temperature and chemical composition of the rock glacier stream. During recent projects, extensive geological mapping has been carried out. Geological mapping shows that the bedrock of the drainage area is part of the tztal-Stubai Complex and consists mainly of paragneiss and mica schist. Ground penetrating radar measurements show a smooth bedrock surface without pronounced ridges or bumps. A maximum thickness of 49 m was recorded. On the surface a layer of coarse debris covers more fine grained material, which is exposed at the front and the margins of HK rock glacier. The average grain size of the debris mantle varies between 0.35 and 0.58 m. Velocities (horizontal displacements) of HK rock glacier culminated in the early 1960s with a maximum value of 3.9 m/yr near the front, followed by a period of low movement with velocities less than 0.5 m/yr until the early 1990s. A second peak is observed in 2004. While a positive correlation of surface movement and air temperature has been found until the early 2000s, recent data suggest a more complex or even reverse relation of surface displacement and air temperature. To determine the thermal regime of HK rock glacier, temperature loggers were installed across the rock glacier at an altitude of 2650 m. The temperature at the bottom of the winter snow cover (BTS) was found to decrease from the lateral parts towards the centre of HK rock glacier. Field campaigns carried out 2010 and 2011 to investigate the spatial distribution of BTS at HK rock glacier and surrounding areas suggest that the extent of permafrost ground decreased since a previous survey in 1976. The hydrological regime of HK shows high diurnal and seasonal variability. The melting of the winter snow pack typically causes discharge peaks during June, single peaks during summer are caused by heavy precipitation events. A high amount of solutes is released from HK during summer rising by a factor of 2 to 5 from the beginning of the melting season until autumn.

Abermann, J.; Fischer, A.; Hartl, L.; Krainer, K.; Nickus, U.; Schneider, H.; Span, N.; Thies, H.

2012-04-01

337

Spatial and temporal variability of air temperature on a melting glacier: atmospheric controls, extrapolation methods and their effect on melt modelling  

NASA Astrophysics Data System (ADS)

Air temperature is a key control in the exchange of energy fluxes at the glacier-atmosphere interface and is also the main input variable in many of the melt models currently used to predict glacier melt across a variety of scales, be these energy balance or temperature-index type of models. The commonly used approach to derive distributed temperature inputs is extrapolation from point measurements with a Lapse Rate (LR) that is often assumed to be constant in time and uniform in space. In this work, temperature data from three Automatic Weather Stations and twelve Temperature Loggers are used to investigate the spatio-temporal variability of temperature over a glacier, its main atmospheric controls, the suitability of extrapolation techniques and their effect on melt modelling. We use data collected on Juncal Norte Glacier, central Chile, during one ablation season. We examine temporal and spatial variability in LRs, together with alternative statistical interpolation methods. Our main result is that the main control over the glacier thermal regime is the development of a katabatic boundary layer (KBL). Katabatic wind occurs at night and in the morning and is eroded in the afternoon. LRs reveal strong diurnal variability, with steeper LRs during the day when the katabatic wind weakens and shallower LRs during the night and morning. We suggest that temporally variable LRs should be used to account for the observed change. They tend to be steeper than equivalent constant LRs, and therefore result in a reduction in simulated melt compared to use of constant LRs. In addition to the temporal variability, the temperature-elevation relationship varies also in space. Differences are evident between local LRs and including such variability in melt modelling affects melt simulations. The LR used for the upper glacier is a key control on the area contributing to melt, and thus on total melt. Extrapolation methods based on the spatial variability of the observations after removal of the elevation trend, such as Inverse Distance Weighting or Kriging, do not seem necessary for simulations of gridded temperature data over a glacier.

Pellicciotti, F.; Petersen, L.; Carenzo, M.

2011-12-01

338

Experimental Testing of Glacier Sliding Laws  

NASA Astrophysics Data System (ADS)

Glacier sliding laws exist in various forms and are applied in modeling of glacier dynamics. Sliding laws have been, in most cases, theoretically derived but not experimentally tested. Under certain conditions ice sliding over a rigid bed will generate cavities in the lees of bedrock bumps. These cavities will redistribute shear stress to regions of the bed that are in contact with ice. Sliding laws that incorporate cavity formation relate drag to the maximum adverse slope of the region of ice-bed contact. Sinusoidal and stepped-bed geometries are, therefore, predicted to affect basal drag differently. A sinusoidal bed is predicted to have a double-valued drag response as a function of sliding velocity, whereas the steady-state drag on a stepped bed with linear adverse slopes is expected to be independent of sliding velocity. We have conducted an experimental study of sliding laws using a ring shear apparatus that slides ice over a rigid bed. The device rotates a ring of ice that is 20 cm wide, 20 cm tall, with outer diameter of 90 cm. The sliding speed at the ice ring's centerline was incrementally stepped between 7.25--324 m/yr, and a vertical stress of 500 kPa was applied to the ice ring. The ice consisted initially of randomly oriented crystals that with sliding quickly developed a fabric like those observed in ice near glacier beds. The temperature of the ice is held at the pressure melting point and is regulated to ~0.01oC by a bath of circulating fluid that surrounds the sample chamber. Experiments have been conducted on a stepped bed with a constant slope of 8.3 and a sinusoidal bed with a wavelength of 183.3 mm and an amplitude of 15.3 mm. Water was allowed to drain from cavities, so effective stress at the bed was equal to the total vertical stress. Our experimental results differ from theoretical predictions. For the stepped bed, a decrease in shear stress of ~50% over a 12-fold increase in velocity is observed, in contrast to theoretical predictions of a constant shear stress. This rate weakening could be attributed to spatial variability in the rheological properties of the ice, or an unresolved three-dimensional effect. Rheological variability could result from steep gradients in deviatoric stress in ice as it moves from above the cavity to the bed. The results from the sinusoidal bed demonstrate a decrease in shear stress with increasing sliding velocity that is larger than with the stepped bed. Thus, the well-described theoretical effect of a sinusoidal bed on rate weakening is augmented by whatever effect is responsible for rate weakening with the stepped bed. These results provide the first experimental targets for models of sliding that attempt to assess effects of ice-bed separation.

Zoet, L.; Iverson, N. R.

2013-12-01

339

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

340

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

NASA Astrophysics Data System (ADS)

We describe an integrated spatially distributed hydrologic and glacier dynamic model, and use it to investigate the effect of glacier recession on streamflow variations for the upper Bow River basin, a tributary of the South Saskatchewan River, Alberta, Canada. Several recent studies have suggested that observed decreases in summer flows in the South Saskatchewan River are partly due to the retreat of glaciers in the river's headwaters. Modeling the effect of glacier changes on streamflow response in river basins such as the South Saskatchewan is complicated due to the inability of most existing physically based distributed hydrologic models to represent glacier dynamics. We compare predicted variations in glacier extent, snow water equivalent (SWE), and streamflow discharge with satellite estimates of glacier area and terminus position, observed glacier mass balance, observed streamflow and snow water-equivalent measurements, respectively over the period of 1980-2007. Observations of multiple hydroclimatic variables compare well with those simulated with the coupled hydrology-glacier model. Our results suggest that, on average, the glacier melt contribution to the Bow River flow upstream of Lake Louise is approximately 22% in summer. For warm and dry years, however, the glacier melt contribution can be as large as 47% in August, whereas for cold years, it can be as small as 15% and the timing of the glacier melt signature can be delayed by a month. The development of this modeling approach sets the stage for future predictions of the influence of warming climate on streamflow in partially glacierized watersheds.

Naz, B. S.; Frans, C. D.; Clarke, G. K. C.; Burns, P.; Lettenmaier, D. P.

2014-02-01

341

Winding for the wind  

Microsoft Academic Search

The mechanical properties and construction of epoxy-impregnated fiber-glass blades for wind turbines are discussed, along with descriptions of blades for the Mod 0A and Mod 5A WECS and design goals for a 4 kW WECS. Multicell structure combined with transverse filament tape winding reduces labor and material costs, while placing a high percentage of 0 deg fibers spanwise in the

O. Weingart

1981-01-01

342

Fifty-Year Record of Glacier Change Reveals Shifting Climate in the Pacific Northwest and Alaska, USA  

USGS Publications Warehouse

Fifty years of U.S. Geological Survey (USGS) research on glacier change shows recent dramatic shrinkage of glaciers in three climatic regions of the United States. These long periods of record provide clues to the climate shifts that may be driving glacier change. The USGS Benchmark Glacier Program began in 1957 as a result of research efforts during the International Geophysical Year (Meier and others, 1971). Annual data collection occurs at three glaciers that represent three climatic regions in the United States: South Cascade Glacier in the Cascade Mountains of Washington State; Wolverine Glacier on the Kenai Peninsula near Anchorage, Alaska; and Gulkana Glacier in the interior of Alaska (fig. 1).

2009-01-01

343

Surge-type Glaciers in the West Kunlun Shan, NW Tibet  

NASA Astrophysics Data System (ADS)

Surge-type glaciers oscillate between long-quiescent phase and short-active phase (i.e. decades of slow flow and shorter periods of rapid flow). Surge-type glaciers are distributed around the world and cluster around specific region and it's believed that at least 1 % of world glacier caused surge. Direct observations are difficult due to decades surge cycle and remote situation. To identify surge-type glacier, surface structures, such as looped-moraine and maze-crevasse, are used alternatively. The mechanisms of glacier surges are still not understood completely but recent studies suggest that glacier surge is likely a result of changing hydrological and/or thermal conditions. Many mountain glaciers are developed in West Kunlun Shan (WKS) located in NW Tibetan plateau. Scherler et al. (2011) mentioned that unusual low velocities at frontal part were associated with past surges in WKS but there are no reports of spatio-temporal data of glacier surge, to our knowledge. We detected glacier surge and its velocity change in WKS. We used offset tracking method based on Synthetic Aperture Radar (SAR) data, assumed that glaciers flow parallel to surface topography derived from SRTM4 digital elevation model and converted offset-results to surface velocity field. Also, we detected glacier front change using SAR intensity images and Landsat optical images. We paid attention to 36 glaciers in WKS. Among 5 glaciers were obviously classified as surge-type glacier. Surface velocity of these glaciers gradually accelerated and decelerated, accompanied by advance of glacier terminus. For example, Chongce glacier on the south slope of WKS was active phase in 1990's. Surface velocity increased up to ~700m/year in 1996. No surge signal detected from 2003. Velocity profile of Chongce glacier dramatically changed. The upper part was ~20-30m/year but the lower part was ~0-5m/year. We detected same behavior at Zhongfeng glacier (branch 1) on the south slope. Except for Chongce glacier and Zhongfeng glacier (branch 1), many glaciers in WKS had stagnant flow and probably classified as surge-type glaciers. However, dead ice caused stagnant flow. Continuous monitoring is necessarily to elucidate entire surge cycle in WKS.

Yasuda, T.; Furuya, M.

2012-12-01

344

Submarine landforms characteristic of glacier surges in two Spitsbergen fjords  

NASA Astrophysics Data System (ADS)

Well-preserved submarine landforms, all less than 100 years old, are imaged on high-resolution swath bathymetry obtained from Van Keulenfjorden and Rindersbukta (inner Van Mijenfjorden), Spitsbergen, Svalbard. Several tidewater glaciers in these fjords have surged in the last few hundred years. Streamlined landforms, found within the limits of known surges, are interpreted as mega-scale glacial lineations (MSGL) formed subglacially beneath actively surging ice. Large transverse ridges are terminal moraines formed by thrusting at the maximum position of glacier surges. Sediment lobes at the distal margins of terminal moraines are interpreted as glacigenic debris flows, formed either by failure of the frontal slopes of thrust moraines or from deforming sediment extruded from beneath the glacier. Sinuous ridges are eskers, formed after surge termination by the sedimentary infilling of subglacial conduits. Concordant ridges, parallel to former ice margins, are interpreted as minor push moraines, probably formed annually during winter glacier readvance. Discordant ridges, oblique to former ice margins, are interpreted as crevasse-squeeze ridges, forming when soft subglacial sediments are injected into basal crevasses. These submarine landforms have been deposited in the following sequence based on cross-cutting relationships between them, linked to stages of the surge cycle: (1) MSGL; (2a) terminal moraines and (2b) lobe-shaped debris flows; (3) isolated areas of crevasse-fill ridges; (4) eskers and (5) annual retreat ridges. A descriptive landsystem model for tidewater surge-type glaciers has been developed, whose wider applicability is emphasised by comparison with two areas in Isfjorden, Spitsbergen. The model also has a number of features in common with landsystem models for terrestrial surge-type glaciers, but is likely to be more complete since submarine landforms are particularly well preserved. The landforms discussed here may be produced and preserved in different proportions in the varied environmental settings where surging glaciers are found.

Ottesen, D.; Dowdeswell, J. A.; Benn, D. I.; Kristensen, L.; Christiansen, H. H.; Christensen, O.; Hansen, L.; Lebesbye, E.; Forwick, M.; Vorren, T. O.

2008-08-01

345

Temperate Ice Under Jakobshavn Isbrae and Other Greenland Glaciers  

NASA Astrophysics Data System (ADS)

Jakobshavn Isbrae, western Greenland's largest outlet glacier, drains 6.5% of the ice sheet's area and therefore may be poised to make rapid contributions to global sea level rise. Indeed, in the late 1990s the glacier doubled in speed as its floating ice tongue disintegrated. Driving stresses up to 300 kPa suggest that a considerable amount of ice deformation combines with basal sliding to produce Jakobshavn's fast speed. Boreholes and overturned icebergs have indicated the existence of a soft, temperate layer at the bottom of the ice, where shear deformation would be concentrated. The thickness and water content of the temperate ice layer determine how much of the motion it can provide. While we focus on Jakobshavn, we also apply our analysis to other Greenland outlet glaciers. This project uses an implicit finite-difference model to compute the temperate ice thickness and water content along multiple flowlines feeding Jakobshavn Isbrae and other Greenland glaciers, in an effort to identify the mechanisms for their rapid movement. In contrast to previous modeling studies, which chose ice velocities in order to match partial temperature profiles measured in boreholes, our model is constrained by satellite-observed surface velocities. The model calculates the temperature field and determines the sliding and internal deformation velocities, constrained by the velocity measurements, to make a self-consistent balance. Feedbacks between temperature, water content, and viscosity allow the temperate shear layer to evolve. Our model results for temperate ice thickness under Jakobshavn (150-300 meters) agree with previous estimates (100-700 meters) and recent observations (30 and 200-250 meters). This model is well suited for glaciers with deeply eroded bedrock troughs. Forthcoming observational campaigns such as NASA's IceBridge program will produce detailed basal topography data for other Greenland outlet glaciers. As these data come online, we will model the temperate ice thickness under Greenland glaciers where field studies of deep ice temperature have not been done.

Poinar, K. E.; Joughin, I. R.

2010-12-01

346

Climate-hydrology-ecology interactions in glacierized river systems  

NASA Astrophysics Data System (ADS)

High climatic sensitivity and low anthropogenic influence make glacierized river basins important environments for examining hydrological and ecological response to global change. This presentation is based on previous and ongoing research in glacierized river basins (located in the French Pyrenees, New Zealand and Swedish Lapland), which adopts an interdisciplinary approach to investigate the climate-hydrology-ecology cascade. Data are used to advance hypotheses concerning impacts of climate change/ variability on glacier river system hydrology and ecology. Aquatic ecosystems in high latitude and altitude environments are influenced strongly by cryospheric and hydrological processes due to links between atmospheric forcing, snowpack/ glacier mass-balance, river runoff, physico-chemistry and biota. In the current phase of global warming, many glaciers are retreating. Shrinking snow and ice-masses may alter spatial and temporal dynamics in bulk basin runoff with significant changes in the relative contributions of snowmelt, glacier-melt and groundwater to stream flow. The timing of peak snow- and ice-melt may shift; and proportion of stream flow sourced from rainfall-runoff and groundwater may increase. In this presentation, the influence of changing water source contributions on physico-chemical habitat and, in turn, benthic communities is assessed using an alternative alpine stream classification. In the future, this model predicts more rapid downstream change in benthic communities as meltwater contributions decline; and, at the basin-scale, biodiversity may be reduced due to less spatio-temporal heterogeneity in water sources contributions and, thus, physico-chemical habitat. Integrated, long-term research into the climate-hydrology-ecology cascade in other glacierized river basins is vital because interdisciplinary science is fundamental: to predicting stream hydrology and ecology under scenarios of future climate/ variability, to assessing the utility of alpine river systems as indicators of global change, and to developing conservation strategies for these fragile ecosystems. Future research imperatives and directions are outlined.

Hannah, David; Brown, Lee; Milner, Alexander

2010-05-01

347

Glacier surface velocity fields in South Shetland Islands  

NASA Astrophysics Data System (ADS)

In this study surface velocity of glaciers in South Shetland Islands (Antarctic Peninsula) are calculated based on synthetic aperture radar data from ALOS PALSAR and TerraSAR-X as well as differential GPS measurements. The obtained glacier velocities will be used to calculate the total glacier mass budget and to better understand the contribution of the study areas to the sea level rise. Only recent studies have examined the region for mass balance and sea level rise estimates. However, larger scale mass budget computations are not yet available. Ice dynamics obtained from satellite data have only been derived in a few occasions, often due to lacking spatial resolution or temporal decorrelation. Hence, any spacebased information on ice dynamics can significantly improve estimates of calving fluxes and mass loss. In this study we analysed over 30 PALSAR and 30 TSX scenes acquired over the King George Island and Livingston Island, the two largest islands in the South Shetland Island group. In the study areas the glacier velocities are calculated using two independent data sets; namely satellite radar imagery and GPS. Feature-tracking methods are applied to the radar imagery to obtain glacier velocities using Gamma Interferometric SAR Processor and TU-Delft DORIS. Results from Gamma and Doris software packages are compared to each other as well as GPS measurements where available. For a subset of the study area tracking results from different acquisitions modes (stripmap and spotlight) and orbits are compared. Comparison of glacier velocities obtained by radar and GPS provide an estimate for the uncertainties in the measured rates. The results obtained from all data sets are then compiled to construct a map of glacier velocities for the entire island group.

Osmanoglu, B.; Giseke, H.; Navarro, F. J.; Rueckamp, M.; Falk, U.; Corcuera, M. I.; Braun, M.

2011-12-01

348

Velocities of Thwaites and Land glaciers  

NASA Technical Reports Server (NTRS)

Changes in the area of volume of polar ice sheets are intricately linked to changes in global climate and may severely impact the densely populated coastal regions on Earth. An ice sheet's velocity is a critical parameter, which, together with ice thickness, allows the determination of discharge rates. Using moderate-resolution satellite images such as Landsat, the velocity of floating ice can be measured quickly and relatively inexpensively by tracing crevasse patterns on shelves and ice tongues. Errors in measured velocities are as little as 0.02 km per year, if the following criteria are met: (1) the time interval is longer than 10 years; (2) the velocity is higher than 0.5 km per year; (3) the coregistration points are well dispersed and enclose the area to be measured; and (4) the image pair includes a Landsat 4 or 5 image. The fewer of these conditions that are met, the less accurate the results become; but even for poor conditions, the velocities are generally reliable to near 0.1 km per year. We are in the process of obtaining velocities of all ice shelves and ice tongues along the Bakutis and Ruppert coasts, wherever suitable crevasse patterns exist. So far, we have obtained velocities for the Thwaites and Land glacier tongues.

Lucchitta, B. K.; Mullins, Kevin F.; Ferrigno, J. G.

1993-01-01

349

Climate change impacts on mountain glaciers and permafrost Due to their proximity to melting conditions under  

E-print Network

Editorial Climate change impacts on mountain glaciers and permafrost Due to their proximity to melting conditions under terrestrial conditions, mountain glaciers and permafrost are particularly). Mountain and lowland permafrost are similarly sensitive to climate changes because of their strong

Raup, Bruce H.

350

1 INTRODUCTION The activity of talus-derived rock glaciers depends on  

E-print Network

. Investiga- tions involved excavation with drilling, triangulation survey, inclinometer measurement, a DC glacier in the Upper Engadin. A borehole 5.4m deep drilled on the upper part of the rock glacier displayed

Kääb, Andreas

351

Calculating snowfall on central Himalayan glaciers: significant winter snowfall on "summer accumulation" glaciers  

NASA Astrophysics Data System (ADS)

Understanding the sources and controls on Himalayan snowfall has important ramifications for predicting dry-season hydrologic fluxes and properly interpreting the paleoclimates associated with past glaciations. Previously, it was assumed that Himalayan glaciers received snow primarily during the June-September summer monsoons. Instead, analysis of meteorological data (1999-2004, 2008 at altitudes 530-5600 m) from the Annapurna region of central Nepal shows that winter (November-April) snows make up roughly half (30-60%) of the annual snow at glacial levels. Less than 45% of the total snowfall probably comes during the actual summer monsoon months. Instead, significant snow accumulates from January to September, while October to December is drier. The parameters that most influence the predicted snow at higher altitudes are the rate at which precipitation is assumed to decrease with altitude and the percent of solid precipitation at near-0C temperatures. Large areas of the studied glaciers have June to August average temperatures within a few degrees C of freezing.

Pratt-Sitaula, B.; Putkonen, J.

2009-12-01

352

Glacier Velocities and Elevation Change of the Juneau Icefield, Alaska  

NASA Astrophysics Data System (ADS)

Mass-loss from small icefields is the greatest contributor from the cryosphere to sea level rise at present. The Juneau Icefield is a small low-latitude glacier system in southeast Alaska. Remote-sensing data from SAR and optical instruments is examined for inter-annual and seasonal changes in glacier elevation and velocity. We use subpixel offset tracking of satellite SAR and optical images to construct a time-series of average horizontal velocities for the outlet glaciers of the icefield. Optical imagery is available from the ASTER instrument between 2000 and 2009. Eighty ASTER scene-pairs are used to generate pixel-offsets for the region. SAR imagery is available for pixel tracking between 1992-2000, although rapid decorrelation means that only repeat track images separated by 1-2 months are useful. The combined radar and optically derived time-series are compared with sparse GPS measurements made by the Juneau Icefield Research Program (JIRP). JIRP measurements and ASTER-derived velocities at the same points show a velocity of up to 1.1 m/day with differences between the two ranging from 0 to 20 cm/day over coherent areas of the ASTER pixel-offsets. Initial findings over Taku Glacier (the largest outlet glacier in the icefield) indicate that velocities from several ERS tandem-pairs, with short duration repeat passes, taken during the mid-1990s reveal velocities in the middle of Taku glacier of 1 m/day to 1.5 m/day over the faster-moving sections of the glacier. These results are within +/- 25 cm/day of velocities derived from the more recent ASTER scenes, which show a maximum average velocity of around 1.25 m/day. However, Taku Glacier is the only glacier in the icefield still advancing and is therefore not representative of the entire icefield. Data covering other outlet glaciers will be processed to determine overall trends in velocity. Several components of the ASTER processing-chain are tested. Output from two independent pixel-tracking software packages that use different algorithms is compared for consistency. Initial results indicate Ampcor, an open source package that forms part of the ROI-PAC software suite, generates similar results to CosiCorr, an open source module for the ENVI image processing software suite. Each package produces an average velocity of up to 1.25 m/day in the middle of Taku Glacier, with differences of up to +/- 10 cm/day over coherent areas. Relative DEMs from cloud-free ASTER pairs are used to determine average rates of surface elevation change over the outlet glaciers of the icefield. An automated DEM differencing tool removes bias in differences between DEMs due to satellite position and filters out clouds and outliers. Changing surface elevation change may be linked to changes in ice dynamics and mass. Deriving glacier velocities and elevation changes from remote-sensing data will provide a comprehensive overview of the "health" of the Juneau Icefield. Understanding the causes of variability in the observations will provide better constraints on how the icefield will react to future climate change.

Melkonian, A. K.; Willis, M. J.; Pritchard, M. E.; Bernstein, S.

2009-12-01

353

Glacier Lake Outburst Floods in Norway 2001 - 2009  

NASA Astrophysics Data System (ADS)

Several GLOFs or jkulhlaups occurred in Norway during the first decade of the millennium, the most significant being several from Rundvassbreen, an outlet glacier of Blmannsisen and one from Flatbreen, an outlet glacier of Jostedalsbreen. A number of minor flood events occurred also. Many of the glaciers in Norway, especially the maritime glaciers with high winter balance, demonstrated frontal advance and positive mass balance in the 1990s. However, since 2000 most glaciers have had a negative mass balance, and undergone frontal retreat and a corresponding decrease in area. The outburst flood from Flatbreen in 2004 was from a moraine-dammed lake that usually drains under the glacier itself. The immediate cause of the flood was a sudden period of warm, wet weather and the sudden increase of additional water into the lake caused the moraine to rupture. Over 50 000 m3 of water drained from the lake, and the resulting debris flow from the lake to the valley 1000 m lower had a volume of 240 000 m3. Fortunately there were no injuries from this flood, but extensive material damage to farmland on the valley floor. Previous, but smaller events occurred from this lake in 1924 and 1947. The moraine is still partially ruptured, thus the potential for a new jkulhlaup of the same magnitude as that in 2004 is greatly reduced. Several floods occurred from a glacier-dammed lake at the glacier Blmannsisen in Nothern Norway, the first occurring in 2001, and subsequently in 2005, 2007 and 2009. The jkulhlaups all occurred in late summer, but at different water levels of the lake. The first two events occurred when the lake was full and 35 - 40 million m3 of water drained. However, the second event occurred a year after the lake had filled again, with the excess water in the meantime draining over a spillway and away from the glacier, as it had done prior to 2001. The two subsequent events occurred before the lake was completely full, and were half the size of the first two events at about 20 million m3 of water. The thickness of ice at the barrier has decreased over the past few decades, which instigated the first event. Comparing measurements in 1961 and 1998, the part of the glacier adjacent to the lake was up to 55 m thinner. Laser scanning performed in autumn 2002 showed a further 4-10 of thinning between 1998 and 2002. GPS measurements on the glacier surface showed that there was thinning of an average of 4.5 m from 2001 to 2004, and a further 5-10 m between 2004 and 2009. This further thinning led to the lake emptying under the glacier at a lower lake level than previously. There were no human or material damages from any of these events. In contrast, the floodwaters flowed into Sisovatn, a hydropower reservoir and were financially beneficial. No similar events have been recorded before the 2001 event. The lake is now expected to continue to empty under the glacier at fairly regular intervals.

Jackson, Miriam; Engeset, Rune

2010-05-01

354

Climate change and tropical Andean glaciers: Past, present and future  

NASA Astrophysics Data System (ADS)

Observations on glacier extent from Ecuador, Peru and Bolivia give a detailed and unequivocal account of rapid shrinkage of tropical Andean glaciers since the Little Ice Age (LIA). This retreat however, was not continuous but interrupted by several periods of stagnant or even advancing glaciers, most recently around the end of the 20th century. New data from mass balance networks established on over a dozen glaciers allows comparison of the glacier behavior in the inner and outer tropics. It appears that glacier variations are quite coherent throughout the region, despite different sensitivities to climatic forcing such as temperature, precipitation, humidity, etc. In parallel with the glacier retreat, climate in the tropical Andes has changed significantly over the past 50-60 years. Temperature in the Andes has increased by approximately 0.1 C/decade, with only two of the last 20 years being below the 1961-90 average. Precipitation has slightly increased in the second half of the 20th century in the inner tropics and decreased in the outer tropics. The general pattern of moistening in the inner tropics and drying in the subtropical Andes is dynamically consistent with observed changes in the large-scale circulation, suggesting a strengthening of the tropical atmospheric circulation. Model projections of future climate change in the tropical Andes indicate a continued warming of the tropical troposphere throughout the 21st century, with a temperature increase that is enhanced at higher elevations. By the end of the 21st century, following the SRES A2 emission scenario, the tropical Andes may experience a massive warming on the order of 4.5-5 C. Predicted changes in precipitation include an increase in precipitation during the wet season and a decrease during the dry season, which would effectively enhance the seasonal hydrological cycle in the tropical Andes. These observed and predicted changes in climate affect the tropical glacier energy balance through its sensitivity to changes in atmospheric humidity (which governs sublimation), precipitation (whose variability induces a positive feedback on albedo) and cloudiness (which controls the incoming long-wave radiation). In the inner tropics air temperature also significantly influences the energy balance, albeit not through the sensible heat flux, but indirectly through fluctuations in the rain-snow line and hence changes in albedo and net radiation receipts. Given the projected changes in climate, based on different IPCC scenarios for 2050 and 2080, simulations with a tropical glacier-climate model indicate that glaciers will continue to retreat. Many smaller, low-lying glaciers are already completely out of equilibrium with current climate and will disappear within a few decades. But even in catchments where glaciers do not completely disappear, the change in streamflow seasonality, due to the reduction of the glacial buffer during the dry season, will significantly affect the water availability downstream. In the short-term, as glaciers retreat and lose mass, they add to a temporary increase in runoff to which downstream users will quickly adapt, thereby raising serious sustainability concerns.

Vuille, Mathias; Francou, Bernard; Wagnon, Patrick; Juen, Irmgard; Kaser, Georg; Mark, Bryan G.; Bradley, Raymond S.

2008-08-01

355

3-D modelling of glacier calving processes (Invited)  

NASA Astrophysics Data System (ADS)

Calving from tidewater glacier tongues and ice shelves is an important mass loss mechanism for many mid- and high-latitude tidewater glaciers, ice caps and ice sheets, yet an adequate representation of calving is still missing from prognostic models of ice dynamics. Benn and others (2007) proposed a calving criterion appropriate for both grounded and floating glacier tongues or ice shelves. This criterion assumes that the calving is triggered by the downward propagation of transverse surface crevasses, near the calving front, as a result of the extensional stress regime. The crevasse depth is calculated following Nye (1957), assuming that the base of a field of closely spaced crevasses lies at a depth where the longitudinal tensile strain rate tending to open the crevasse equals the creep closure resulting from the ice overburden pressure. Crevasses partially or totally filled with water will penetrate deeper, because of the contribution of water pressure to the opening of the crevasse. This criterion is readily incorporated into glacier and ice sheet models, but has not been fully validated with observations. We apply a three-dimensional extension of Benn and others (2007) criterion, incorporated into a full-Stokes model of glacier dynamics, to estimate the current position of the calving front of Johnsons Glacier, Antarctica. The record of the front positions of Johnsons Glacier spans only a few years during the last decade, and during this observation period the front has remained at a nearly constant position, so a full modelling exercise of time evolution to follow the front-position changes of the glacier has not been possible. Instead, our modelling experiment is a diagnostic one, aimed at establishing whether the model adequately reproduces the current front position of Johnsons Glacier (Otero et al., 2010). We develop four experiments: (i) an straightforward three-dimensional extension of Benn and others (2007) model; (ii) an improvement to the latter that computes the tensile deviatoric stress opening the crevasse using the full-stress solution; (iii) a further improvement based on finding the depth at which the model-computed tensile deviatoric stress, considered as a function of depth, equals the ice overburden closure pressure; (iv) an experiment that adds, to the above, the effect of a threshold strain rate required for crevasses initiation. We found that the improvements considered in experiments (ii) and (iii) were necessary to reproduce accurately the observed calving front. In ongoing work, we intend to apply our model in a prognostic mode, to predict the observed front position changes of Hansbreen, a tidewater glacier in Svalbard. REFERENCES: Benn, D.I., R.J. Hulton and R.H. Mottram. 2007. Calving laws, sliding laws and the stability of tidewater glaciers. Ann. Glaciol., 46, 126-130. Nye, J.F. 1957. The distribution of stress and velocity in glaciers and ice-sheets. Proc. Roy. Soc., Ser. A, 239(1216), 113-133. Otero, J., F.J. Navarro, C. Martn, M.L. Cuadrado and M.I. Corcuera. 2010. A three-dimensional calving model: numerical experiments on Johnsons Glacier, Livingston Island, Antarctica. J. Glaciol., 56(196), 200-214.

Navarro, F. J.

2010-12-01

356

Modeling future sea level rise from melting glaciers  

NASA Astrophysics Data System (ADS)

Melting mountain glaciers and ice caps (MG&IC) are the second largest contributor to rising sea level after thermal expansion of the oceans and are likely to remain the dominant glaciological contributor to rising sea level in the 21st century. The aim of this work is to project 21st century volume changes of all MG&IC and to provide systematic analysis of uncertainties originating from different sources in the calculation. I provide an ensemble of 21st century volume projections for all MG&IC from the World Glacier Inventory by modeling the surface mass balance coupled with volume-area-length scaling and forced with temperature and precipitation scenarios from four Global Climate Models (GCMs). By upscaling the volume projections through a regionally differentiated approach to all MG&IC outside Greenland and Antarctica (514,380 km 2) I estimated total volume loss for the time period 2001-2100 to range from 0.039 to 0.150 m sea level equivalent. While three GCMs agree that Alaskan glaciers are the main contributors to the projected sea level rise, one GCM projected the largest total volume loss mainly due to Arctic MG&IC. The uncertainties in the projections are addressed by a series of sensitivity tests applied in the methodology for assessment of global volume changes and on individual case studies for particular glaciers. Special emphasis is put on the uncertainties in volume-area scaling. For both, individual and global assessments of volume changes, the choice of GCM forcing glacier models is shown to be the largest source of quantified uncertainties in the projections. Another major source of uncertainty is the temperature forcing in the mass balance model depending on the quality of climate reanalysis products (ERA-40) in order to simulate the local temperatures on a mountain glacier or ice cap. Other uncertainties in the methods are associated with volume-area-length scaling as a tool for deriving glacier initial volumes and glacier geometry changes in the volume projections. Nevertheless, the lack of more detailed knowledge of global ice volume constrains the estimates of the potential and projected sea level rise from melting MG&IC. Any progress in this field is limited without a more complete glacier inventory database.

Radic, Valentina

357

Southern Alaska Glaciers: Spatial and Temporal Variations in Ice Volume  

NASA Astrophysics Data System (ADS)

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. To obtain the optimal ICESat results, we are reprocessing the ICESat data from Alaska to provide a well-calibrated regional ICESat solution. We anticipate that our ICESat results combined with earlier data will provide new constraints on the temporal and spatial variations in ice volume of individual Alaskan mountain ranges. These results allow us to address how recent melting of the southern Alaska glaciers contribute to short-term sea-level rise. Our results will also enable us to quantify crustal stress changes due to ice mass fluctuations and to assess the influence of ice mass changes on the seismically active southern Alaskan plate boundary zone.

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

2004-12-01

358

The Status of Glaciers in the Hindu Kush-Himalayas from satellite data  

NASA Astrophysics Data System (ADS)

In contrary to general glacier retreat in this vast Hindu Kush-Himalayan (HKH) region, some of the glaciers are advancing in the Karakorum (Hewitt, 1985). To understand the climate change impacts on glaciers, it is crucial to update the glacier status. The bigger concern in the HKH region, however, is the lack of long-term information on glaciers at the regional level for any kind of credible baseline or assessment of change. Hence to provide the up to date glacier information the glacier inventory was carried out using a single source satellite images of latest date so far possible. The present mapping of glaciers is the first effort of homogeneous glacier inventory of entire Hindu Kush-Himalayan region, which made the first time reporting of glaciers from Myanmar and first generation of glacier mapping and inventory of Afghanistan and Jammu & Kashmir and Arunachal states of India for ICIMOD. For Nepal, Bhutan, Pakistan, some states of India (Himachal, Uttarakhand and Sikkim) and Ganges basin in China will be the second generation glacier mapping and inventory of ICIMOD. The inventory is based on Landsat 7 ETM+ satellite images from 20053 years and SRTM DEM. The methodology of semi-automatic mapping and inventory is developed and implemented in the present study for quick delivery of glacier database. A first attempt is also made to map and deliver the Clean Ice and Debris Cover glaciers data separately. The glacier parameters like Glacier ID (Watershed and GLIMS), Area (Debris Cover and Clean Ice), Elevation, Slope, Aspect, Thickness, Ice reserve and 100m Glacier Area-Altitude bins are generated. The glaciers with sizes larger than 0.02 km2 are mapped. From the entire HKH region about 54,800 glaciers are mapped with about 60,400 km2 glacier area and 6,100 km3 estimated ice reserves. It was found that the average glacier area of the HKH region is 1.10 km2 per glacier (Bajracharya and others 2011).

Bajracharya, S. R.; Maharjan, S.; Shrestha, F.; Shrestha, B.; Wanqin, G.; Shiyin, L.; Xiaojun, Y.; Khattak, G. A.

2011-12-01

359

A regional view of fluctuations in glacier length in southern South America  

NASA Astrophysics Data System (ADS)

Fluctuations in the length of 72 glaciers in the Northern and Southern Patagonia Icefield (NPI and SPI, respectively) and the Cordillera Darwin Icefield (CDI) were estimated between 1945 and 2005. The information obtained from historical maps based on 1945 aerial photographs was compared to ASTER and Landsat satellite images and to information found in the literature. The majority of glaciers have retreated considerably, with maximum values of 12.2 km for Marinelli Glacier in the CDI, 11.6 km for O'Higgins Glacier in the SPI and 5.7 km for San Rafael Glacier in the NPI. Among the 20 glaciers that have retreated the most relative to their size, small (less than 50 km) and medium (between 50 and 200 km) glaciers are the most affected. However, no direct relation between glacier retreat and size was found for the 72 glaciers studied. The highest percentage retreat in the CDI was by the CDI-03 Glacier (37.9%) and Marinelli Glacier (37.6%). In the SPI, relative retreats were heterogeneous and fluctuated between 27.2% (Amelia Glacier) and 0.4% (Viedma Glacier). In the NPI, relative retreat was very high for Strindberg and Cachet glaciers (35.9% and 27.6%, respectively) but for the remaining glaciers in this icefield it ranged between 11.8% (Piscis Glacier) and 3.6% (San Quintn Glacier). In addition to surface area, the surface slope (calculated on the basis of the DEM SRTM) was also related to the relative retreat and no straightforward relation was found. From a global point of view, we suggest that glacier retreat in the region is controlled firstly by atmospheric warming, as it has been reported in this area. Besides the general increase in temperature observed, no signal of a geographical pattern for the fluctuations in glacier length was found. Consequently, glaciers appear to initially react to local conditions most probably induced by their exposition, geometry and hypsometry. The heterogeneity of rates of retreat suggests that differences in basin geometry, glacier dynamics and response time are key features to explain fluctuations of each glacier.

Lopez, Paulina; Chevallier, Pierre; Favier, Vincent; Pouyaud, Bernard; Ordenes, Fernando; Oerlemans, Johannes

2010-03-01

360

Modeling on the Steady State of Thwaites Glacier  

NASA Astrophysics Data System (ADS)

Thwaites Glacier (TWG) is the second largest ice stream in West Antarctica in terms of ice discharge, and the broadest ice stream in Antarctica (120 km wide). Observations and theory suggest that its configuration is inherently unstable in a warming climate. Satellite observations have revealed grounding line retreat, ice thinning, ice stream broadening and in more recent years ice flow acceleration. The most important part of the glacier evolution involves its grounding line dynamics and the impact of ice-ocean interactions. In a region between the grounding line and the limit of the flexure zone, some 10 km downstream, however, the glacier is not in hydrostatic equilibrium. Proper treatment of the grounding line dynamics requires full Stokes solution. Here, we model the grounding line of TWG in 2D, full Stokes, with the goal to examine whether the glacier is in a steady state configuration or not. The model treats ice sheet and ice shelf as two fluids coupled through the ice mass flux (Nowicki, 2008). Water stress is used as a constraint on the ice shelf instead of hydrostatic equilibrium. We use radar interferometry (InSAR) measurements of ice velocity and grounding line position through time, Bedmap2 and IceBridge thickness, and surface mass balance from RACMO to constrain the model. The results are used to conclude on the state of dynamic balance of the glacier. This work is funded by NASA Cryospheric Science Program.

Yu, H.; Rignot, E. J.; Morlighem, M.; Seroussi, H.

2013-12-01

361

Bacterial succession in a glacier foreland of the High Arctic  

PubMed Central

Succession is defined as changes in biological communities over time. It has been extensively studied in plant communities, but little is known about bacterial succession, in particular in environments such as High Arctic glacier forelands. Bacteria carry out key processes in the development of soil, biogeochemical cycling, and facilitating plant colonization. In this study we sampled two roughly parallel chronosequences in the foreland of Midre Lovn glacier on Svalbard, Norway and tested whether any of several factors were associated with changes in the structure of bacterial communities, including time after glacier retreat, horizontal variation caused by the distance between chronosequences, and vertical variation at two soil depths. The structures of soil bacterial communities at different locations were compared using terminal restriction fragment length polymorphisms (T-RFLP) of 16S rRNA genes, and the data were analyzed by sequential analysis of log-linear statistical models. While no significant differences in community structure were detected between the two chronosequences, statistically significant differences between sampling locations in the surface and mineral soils could be demonstrated even though glacier forelands are patchy and dynamic environments. These findings suggest bacterial succession occurs in High Arctic glacier forelands but may differ in different soil depths. PMID:19587774

Schutte, Ursel M.E.; Abdo, Zaid; Bent, Stephen J.; Williams, Christopher J.; Schneider, G. Maria; Solheim, Bj?rn; Forney, Larry J.

2009-01-01

362

Projecting West Greenland's future tidewater glacier discharge with Monte Carlo  

NASA Astrophysics Data System (ADS)

Due to non-linear feed backs arising from the acceleration of outlet glaciers, it is difficult to forecast the future ice dynamic contribution of Greenland's tidewater glaciers to sea level rise. We perform Monte Carlo simulations of the form and flow of West Greenland over a wide parameter space using a 2-D (depth-integrated) thermo-mechanical ice flow model. Climate forcing is prescribed as a perturbation from the past and future surface mass balance rate predicted by MAR (Modle Atmosphrique Rgional). While more sophisticated ice sheet models exist (e.g. 3-D Navier-Stokes), employing a more computationally efficient model allows us to perform a large number of fully-transient simulations in order to quantify the cumulative uncertainty in projected tidewater glacier discharge stemming from poorly constrained or understood processes, such as the rheology of Wisconsin ice, ice temperature and basal sliding. Following a forward model selection approach, an ensemble filter is imposed following transient spin-up to ensure that only simulations that accurately reproduce contemporary observed glacier geometry and velocity are forced into the future; all other simulations are discarded. This approach therefore provides the opportunity to assimilate spatially and temporally diverse field observations into a predictive modeling framework. We present bounded estimates of the dynamic discharge of several well-observed West Greenland tidewater glaciers to the year 2100.

Colgan, William; Rajaram, Harihar; Fettweis, Xavier

2013-04-01

363

Load Sensitivity of a Surge-Type Glacier  

NASA Astrophysics Data System (ADS)

During the winter season Trapridge Glacier, Yukon, Canada, is subject to puzzling short-lived mechanical events. Such events are characterized by a pronounced increase in icequake activity, abrupt changes in the internal ice strain, and rapid local adjustments of the mechanical interaction between the glacier and its bed. Although the events are closely monitored by a network of englacial and subglacial instruments (including geophones and sensors to measure vertical strain, subglacial water pressure, basal sliding, and sediment strength) it has been unclear, until recently, whether the events are internally or externally triggered. Observations during the winters of 1999--2000 and 2002--2003 indicate that the events are externally triggered and that the forcing mechanism is rapid barometric and/or precipitation loading of the glacier surface. Such sensitivity to small changes in loading is unexpected and suggests that some fraction of the sediment substrate of Trapridge Glacier is near the threshold for mechanical failure. Winter triggering of glacier surges might be explained by fast surface loading.

Clarke, G. K.

2003-12-01

364

Changing Hydrology in Glacier-fed High Altitude Andean Peatbogs  

NASA Astrophysics Data System (ADS)

Montane peatbogs in the glacierized Andean highlands of Peru and Bolivia provide critical forage for camelids (llama and alpaca) in regionally extensive pastoral agriculture systems. During the long dry season, these wetlands often provide the only available green forage. A key question for the future of these peatbog systems, and the livelihoods they support, is the impact of climate change and glacier recession on their hydrology, and thus forage production. We have already documented substantial regional glacier recession, of, on average, approximately 30% of surface area over the past two decades. As glaciers begin to retreat under climate change, there is initially a period of increased meltwater outflow, culminating in a period of "peak water", and followed by a continual decline in outflows. Based on previous work, we know that some glaciers in the region have already passed peak water conditions, and are now declining. To better understand the impacts of these processes on peatbog hydrology and productivity, we have begun collecting a variety of surface data at several study sites in both Bolivia and Peru. These include precipitation, stream flow, water levels, water chemistry and isotope analyses, and peatbog biodiversity and biomass. These measurements will be used in conjunction with a regional model driven by satellite data to predict likely future impacts. We will present the results from these initial surface measurements, and an overview of satellite datasets to be used in the regional model.

Slayback, D. A.; Yager, K.; Baraer, M.; Mohr, K. I.; Argollo, J.; Wigmore, O.; Meneses, R. I.; Mark, B. G.

2012-12-01

365

Conditions determining the partitioning of ablation between melt and sublimation on East African glaciers  

Microsoft Academic Search

A new automatic weather station on Lewis Glacier on Mount Kenya (009' S; 3718' E) allows comparison of the surface energy balance there with that of Kersten glacier on Kibo, Kilimanjaro (304' S; 3721' E), which is ca. 320 km to the south. Lewis Glacier, at about 4800m is ca. 1000m lower than Kersten Glacier and annual mean temperature is

L. I. Nicholson; R. Prinz; T. Moelg; G. Kaser

2010-01-01

366

Variations in ELA of glaciers in the Tibetan Plateau over the past two decades and their implications for future glacier change  

NASA Astrophysics Data System (ADS)

The equilibrium line altitude (ELA) is a theoretical line on a glacier at which annual mass accumulation equals annual mass loss. Glacier behaviors such as advancing or retreating are controlled by the variations in ELA. Relative to its steady state, a glacier advances when its ELA falls, retreats when its ELA rises, or melts entirely when its ELA rises above its summit. In contrast to variations in glacier length or area, variations in ELA respond almost simultaneously to climate change. With global warming, studying ELA variations is of prime importance for understanding the behaviors of glaciers. Based on observations of the ELAs of the Qiyi Glacier in the Qilian Mountains, the Meikuang Glacier in the Kunlun Mountains and the Xiaodongkemadi Glacier in the Tanggula Mountains in the Tibetan Plateau, we found that the ELAs have risen about 160-180m since 1989. After analyzing the correlations between the ELAs and air temperature and precipitation, it was found that the warm season air temperature was the leading climatic factor influencing ELA. The present ELAs of those observed glaciers are much higher than their ELAs under the status of that their mass balances are zero. This suggests that those glaciers will continue to retreat in the near future.

Wang, N.; Pu, J.; Duan, K.; Yao, T.

2013-05-01

367

Geomorphic consequences of two large glacier and rock glacier destabilizations in the Central and northern Chilean Andes  

NASA Astrophysics Data System (ADS)

Mountain areas are occasionaly affected by complex mass movements of high magnitude and large extent, which generally involve water, snow, rock and ice in variable proportions. Those events can take the form of rock avalanche, landslide, debris flow, glacier collapse or a combination of these phenomenons. In the Central Andes of Chile, they affect hardly accessible regions with low population, explaining the scarcity of previous studies. Nevertheless, during the last 30 years, some documented examples of such events in this region have shown that the volume of material involved is in the order of several millions of m, the areas affected can reach several tenth of km and the velocity of the movement can exceed several tenths of m/s. In this context, this study intends i) to inventory and to describe the main characteristics of events previously documented in the Central Andes of Chile, and ii) analyse in detail two recent events (2005-2007) never described before which have affected in one case a glacier and in another case a rock glacier. With the objectives of determining the possible chain of triggering factors and interpreting the event's significance in terms of geomorphic, cryogenic and climatic dynamics, we used air photographs, satellite imagery (Landsat TM & ETM+; Quick Bird when available in Google Earth 5.0), data from the closest meteorological stations, glacier mass balance data and seismic records to investigate the collapse of a rock glacier occurred in 2006 on the west-facing flank of the Cerro Las Trtolas (6160 m asl; 2958' S. - 6955' W.), in the arid North of Chile, and the collapse of a glacier that occurred during austral summer 2006-2007 on the South side of the Tinguiririca Volcano (4075 m asl; 3448' S. - 7021' W.). The rock glacier collapse of the Cerro Las Trtolas West flank occurred during the spring of 2006, but signs of destabilization were already observable since the end of 2005. The deposit of the collapsed mass of the glacier covered 0.12km, nevertheless part of the material mobilized was channelised in a 200m-wide ravine generating an hyper-concentrated flow of snow, ice, water and debris, which traveled for 3 km downslope. The event of the Tinguiririca Volcano South flank occurred between the 29th of December 2006 and the 14th of January 2007 and affected a mountain glacier of 0.46 km. The destabilization of this later led to a quasi complete detachment of the glacier mass, which flowed to the bottom of the valley and, incorporating rock debris, snow and water, traveled downslope for more than 7 km. The destabilization and collapse of both studied landforms occurred during exceptionnaly warm periods of spring and summer and the climatic conditions produced intense glacier downwasting in Chile. This situation might have favoured the destabilization, either by reducing the basal friction of the glacier or by saturating the detritic sole of the rock glacier, both mechanisms being related to large quantity of melt water in the system. Although further research is needed, this temporal concordance suggests that those extreme geomorphologic phenomenons could be partly related to warming air temperatures.

Iribarren Anacona, Pablo; Bodin, Xavier

2010-05-01

368

Ablation and associated energy balance of a horizontal glacier surface on Kilimanjaro  

E-print Network

Ablation and associated energy balance of a horizontal glacier surface on Kilimanjaro Thomas Mo of a glacier describes the physical connection between ice/snow ablation and climatic forcing. To expand knowledge on the response of Kilimanjaro's glaciers to climate variations, this study estimates the energy

Massachusetts at Amherst, University of

369

Inactive and relict rock glaciers of the Deboullie Lakes Ecological Reserve, northern Maine, USA  

Microsoft Academic Search

Lobate talus slopes in the Deboullie Lakes Ecological Reserve (DLER) of northern Maine exhibit parabolic profiles characteristic of inactive and relict talus-derived rock glaciers. Vegetated rock glacier surfaces suggest that the landforms are no longer active, and lobes comprising two DLER rock glaciers document periods of past growth. Observations of perennial subsurface ice are supported by datalogger temperature measurements, indicating

Aaron E. Putnam; David E. Putnam

2009-01-01

370

Mechanical and hydrologic basis for the rapid motion of a large tidewater glacier. 1: Observations  

Microsoft Academic Search

Measurements of glacier flow velocity and basal water pressure at two sites on Columbia Glacier, Alaska, are combined with meteorological and hydrologic data to provide an observational basis for assessing the role of water storage and basal water pressure in the rapid movement of this large glacier. During the period from July 5 to August 31, 1987, coordinated observations were

Mark Meier; Scott Lundstrom; Dan Stone; Barclay Kamb; Hermann Engelhardt; Neil Humphrey; William W. Dunlap; Mark Fahnestock; Robert M. Krimmel; Roy Walters

1994-01-01

371

Recent ice loss from the Fleming and other glaciers, Wordie Bay, West Antarctic Peninsula  

E-print Network

an ice shelf is afloat in the ocean, its removal does not change sea level, but it may affect glacierRecent ice loss from the Fleming and other glaciers, Wordie Bay, West Antarctic Peninsula E. Rignot ice thickness data from 2002, reveal that the glaciers flowing into former Wordie Ice Shelf, West

Kansas, University of

372

Modelling the Backscatter Response of Different Zones Within a Polar Glacier  

Microsoft Academic Search

In order to better quantify the causes of backscatter in glaciers, we model the backscatter response of a polar glacier to C-band GPR imaging. The motivation for such modeling is the need to develop improved algorithms for glacier parameter retrieval from SAR data, including snow facies type, accumulation rate, etc.. These efforts require a better understanding of C-band scattering mechanisms

K. Langley; K. Meuller; O. Brandt; E. Hamran

2005-01-01

373

Composition and internal structures of a rock glacier on the strandflat of western Spitsbergen, Svalbard  

Microsoft Academic Search

This article presents data on composition and internal structures of a large lobe-shaped rock glacier at Nordenskioldkysten, western Spitsbergen, based on Ground Penetrating Radar (GPR) and direct current (DC) resistivity tomography measurements. This rock glacier has a more complex surface topography than most rock glaciers in Svalbard and is probably also older. The GPR data indicate a quite chaotic structural

Herman Farbrot; Ketil Isaksen; Trond Eiken; Andreas Kb; JOHAN LUDVIG SOLLID

2005-01-01

374

Contribution potential of glaciers to water availability in different climate regimes  

E-print Network

Contribution potential of glaciers to water availability in different climate regimes Georg Kaser the contribution potential of seasonally delayed glacier melt water to total water availability in large river missing, considerable detrimen- tal changes due to shrinking glaciers are universally expected for water

Marzeion, Ben

375

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

Microsoft Academic Search

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

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

2009-01-01

376

Estimation of Alpine glacier water resources and their change since the 1870s  

Microsoft Academic Search

An empirical formula relating volume of an Alpine glacier to the surface area is improved based on the data measured by radio-echo sounding and seismic method. The formula is used for calculating the present volume of the Alpine glaciers based on the surface-area data registered in the World Glacier Monitoring Service. The past volumes at several stages are estimated from

Jiyang Chen; Atsumu Ohmura

1990-01-01

377

Changes in glacier extent on north Novaya Zemlya in the twentieth century  

Microsoft Academic Search

Glacier retreat on north Novaya Zemlya for the past century was documented by registering glacier terminus positions from expedition and topographic maps and remotely sensed images. Recession of tidewater calving glaciers on north Novaya Zemlya in the first half of the twentieth century was relatively rapid (>300 m yr-1), consistent with post-Little Ice Age warming documented by a 122-year instrumental

Jaapjan Zeeberg; Steven L. Forman

2001-01-01

378

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

Microsoft Academic Search

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)

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

2002-01-01

379

Geometry and dynamics of two lobe-shaped rock glaciers in the permafrost of Svalbard  

E-print Network

Geometry and dynamics of two lobe-shaped rock glaciers in the permafrost of Svalbard ANDREAS KA¨ A. Geometry and dynamics of two lobe-shaped rock glaciers in the permafrost of Svalbard. Norsk Geogra sk. While rock glaciers on Sval- bard represent creep of cold and continuous polar permafrost, those

Kääb, Andreas

380

Thirty-year history of glacier melting in the Nepal Himalayas Koji Fujita,1  

E-print Network

Thirty-year history of glacier melting in the Nepal Himalayas Koji Fujita,1 Lonnie G. Thompson,2 of glacier melting in the Nepal Himalayas, J. Geophys. Res., 111, D03109, doi:10.1029/2005JD005894. 1. Introduction [2] Rapid shrinkage of glaciers in the Nepal Himalayas has been observed during recent decades [e

Howat, Ian M.