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1

Glaciers  

NSDL National Science Digital Library

This is a great site to help you learn about glaciers! On this webpage, you will learn what glaciers are, how they are formed, the different types of glaciers, their anatomy, how they move, and about glacial erosion. This site also has a model that helps you to understand glacial growth and retreat.

2010-01-01

2

Glaciers  

NSDL National Science Digital Library

Glaciers are found on every continent except Australia. This interactive feature provides an introduction to these moving streams of ice, which cover about 10 percent of Earth's land surface and hold between two and three percent of its water. Topics include what glaciers are, where and why they form, what influences their growth and decline, and how an apparently solid mass appears to flow like a river. There is also a brief description of some types of glaciers. A background essay and discussion questions are included.

2010-09-28

3

Glaciers  

NSDL National Science Digital Library

Glaciers are found on every continent except Australia. This interactive feature provides an introduction to these moving streams of ice, which cover about 10 percent of Earth's land surface and hold between two and three percent of its water. Topics include what glaciers are, where and why they form, what influences their growth and decline, and how an apparently solid mass appears to flow like a river. There is also a brief description of some types of glaciers. A background essay and discussion questions are included.

4

77 FR 62504 - Combined Notice of Filings #1  

Federal Register 2010, 2011, 2012, 2013, 2014

...ER11- 4670-001. Applicants: NaturEner Glacier Wind Energy 1, LLC, NaturEner Glacier Wind Energy 2, LLC, NaturEner Power Watch...Description: Notice of Change in Facts of NaturEner Glacier Wind Energy 1, LLC, et al. Filed Date:...

2012-10-15

5

Glaciers  

NSDL National Science Digital Library

In this online activity, learners adjust mountain snowfall and temperature to see how glaciers grow and shrink. They will use scientific tools to measure thickness, velocity and glacial budget. This activity includes an online simulation, sample learning goals, teaching ideas, and translations in over 20 languages.

2012-11-14

6

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.

7

Wind-driven modulation of warm water supply to a proglacial fjord, Jorge Montt Glacier, Patagonia  

NASA Astrophysics Data System (ADS)

Projections of sea level rise due to ice loss from the land to the ocean have been hampered by a lack of understanding of the role the ocean is playing in glacier retreat, including the processes that contribute to the supply of warm water to the ice-ocean interface. Here shipboard, moored, and weather station data collected off Jorge Montt, a rapidly retreating glacier in Patagonia, are analyzed to understand the influence of wind forcing. During summer, synoptic-scale down-fjord wind events enhance an estuarine-like two-layer flow, increasing the inflow of oceanic deep water. During up-fjord wind events, the inflow of deep water is significantly reduced, and a three-layer exchange flow develops. Overall, along-fjord wind forcing is shown to modulate the inflow of warm water to the fjord by a factor of 2.5 The results suggest that local, channelized winds can be an important process modulating warm water supply and melting of tidewater glaciers.

Moffat, Carlos

2014-06-01

8

76 FR 62791 - Combined Notice of Filings #2  

Federal Register 2010, 2011, 2012, 2013, 2014

...ER11-4666-000. Applicants: NaturEner Glacier Wind Energy 1, LLC. Description: NaturEner Glacier Wind Energy 1, LLC submits tariff filing...ER11-4667-000. Applicants: NaturEner Glacier Wind Energy 2, LLC. Description:...

2011-10-11

9

77 FR 38044 - Combined Notice of Filings #1  

Federal Register 2010, 2011, 2012, 2013, 2014

...EG12-79-000. Applicants: NaturEner Glacier Wind Energy 1, LLC. Description: Notice...Wholesale Generator Status of NaturEner Glacier Wind Energy 1, LLC. Filed Date: 6...ER12-2057-000. Applicants: NaturEner Glacier Wind Energy 1, LLC. Description:...

2012-06-26

10

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

11

Bivachnyy Glacier  

USGS Multimedia Gallery

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

12

Glacier Melt  

NSDL National Science Digital Library

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

Geographic, National

13

Glacier Maker  

NSDL National Science Digital Library

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

14

78 FR 64488 - Combined Notice of Filings #2  

Federal Register 2010, 2011, 2012, 2013, 2014

...Due: 5 p.m. ET 11/7/13. Docket Numbers: ER14-118-000. Applicants: NaturEner Glacier Wind Energy 1, LLC. Description: NaturEner Glacier Wind Energy 1, LLC submits tariff filing per 35.15: Notice of Cancellation of...

2013-10-29

15

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

16

Western Glacier Stonefly  

USGS Multimedia Gallery

The rare western glacier stonefly (Zapada glacier)is native to Glacier National Park and is seeking habitat at higher elevations due to warming stream temperature and glacier loss due to climatewarming. ...

17

Western Glacier Stonefly  

USGS Multimedia Gallery

The rare western glacier stonefly (Zapada glacier)is native to Glacier National Park and is seeking habitat at higher elevations due to warming stream temperature and glacier loss due to climatewarming. ...

18

Glacier Caves  

NSDL National Science Digital Library

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

19

A study of turbulent fluxes and their measurement errors for different wind regimes over the tropical Zongo glacier (16 S) during the dry season  

NASA Astrophysics Data System (ADS)

Over glaciers in the outer tropics, during the dry winter season, turbulent fluxes are an important sink of melt energy due to high sublimation rates, but measurements in stable surface layers, in remote and complex terrains remain challenging. Eddy-covariance (EC) and bulk-aerodynamic (BA) methods were used to estimate surface turbulent heat fluxes of sensible (H) and latent heat (LE) in the ablation zone of the tropical Zongo glacier, Bolivia (16 S, 5080 m a.s.l.), from 22 July to 1 September 2007. We studied the turbulent fluxes and their associated random and systematic measurement errors under the three most frequent wind regimes. For nightly, density-driven katabatic flows, and for strong downslope flows related to large-scale forcing, H generally heats the surface (i.e., is positive), while LE cools it down (i.e., is negative). On average, both fluxes exhibit similar magnitudes and cancel each other out. Most energy losses through turbulence occur for daytime upslope flows, when H is weak due to small temperature gradients and LE is strongly negative due to very dry air. Mean random errors of the BA method (6% on net H + LE fluxes) originated mainly from large uncertainties in roughness lengths. For EC fluxes, mean random errors were due mainly to poor statistical sampling of large-scale outer-layer eddies (12%). The BA method is highly sensitive to the method used to derive surface temperature from long-wave radiation measurements and underestimates fluxes due to vertical flux divergence at low heights and nonstationarity of turbulent flow. The EC method also probably underestimates the fluxes, but to a lesser extent, due to underestimation of vertical wind speed and to vertical flux divergence. For both methods, when H and LE compensate each other in downslope fluxes, biases tend to cancel each other out or remain small. When the net turbulent fluxes (H + LE) are the largest in upslope flows, nonstationarity effects and underestimations of the vertical wind speed do not compensate, and surface temperature errors are important, so that large biases on H + LE are expected when using both the EC and the BA method.

Litt, M.; Sicart, J.-E.; Helgason, W.

2015-01-01

20

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

21

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

22

Glacier microseismicity  

USGS Publications Warehouse

We present a framework for interpreting small glacier seismic events based on data collected near the center of Bering Glacier, Alaska, in spring 2007. We find extremely high microseismicity rates (as many as tens of events per minute) occurring largely within a few kilometers of the receivers. A high-frequency class of seismicity is distinguished by dominant frequencies of 2035 Hz and impulsive arrivals. A low-frequency class has dominant frequencies of 615 Hz, emergent onsets, and longer, more monotonic codas. A bimodal distribution of 160,000 seismic events over two months demonstrates that the classes represent two distinct populations. This is further supported by the presence of hybrid waveforms that contain elements of both event types. The high-low-hybrid paradigm is well established in volcano seismology and is demonstrated by a comparison to earthquakes from Augustine Volcano. We build on these parallels to suggest that fluid-induced resonance is likely responsible for the low-frequency glacier events and that the hybrid glacier events may be caused by the rush of water into newly opening pathways.

West, Michael E.; Larsen, Christopher F.; Truffer, Martin; O'Neel, Shad; LeBlanc, Laura

2010-01-01

23

Jakobshavn Glacier  

Atmospheric Science Data Center

... are visible in the bright white ice. A scattering of small icebergs in Disco Bay adds a touch of glittery sparkle to the scene. The ... for a large portion of the western side of the ice sheet. Icebergs released from the glacier drift slowly with the ocean currents and ...

2013-04-17

24

Fast tidewater glaciers  

Microsoft Academic Search

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

M. F. Meier; Austin Post

1987-01-01

25

Shepard Glacier, Glacier National Park, Montana - 2005  

USGS Multimedia Gallery

The thick, crevassed, ice flows of historic Shepard Glacier have been diminished to less than 0.1 square kilometer in area by 2005. According to the criteria set by the USGS Repeat Photography Project, Shepard Glacier is now considered to be too small to be defined as a glacier. (Blase Reardon)...

26

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 ...

27

Glacier (?) National Park  

NSDL National Science Digital Library

This activity engages learners in examining data pertaining to the disappearing glaciers in Glacier National Park. After calculating percentage change of the number of glaciers from 1850 (150) to 1968 (50) and 2009 (26), students move on to the main glacier-monitoring content of the module--area vs. time data for the Grinnell Glacier, one of 26 glaciers that remain in the park. Using a second-order polynomial (quadratic function) fitted to the data, they extrapolate to estimate when there will be no Grinnell Glacier remaining (illustrating the relevance of the question mark in the title of the module).

Mcllrath, University O.; Curriculum/serc, Spreadsheets A.

28

Muir Glacier in Glacier Bay National Monument 1941  

USGS Multimedia Gallery

This August 1941 photograph is of Muir Glacier in Glacier Bay National Monument, Alaska. It shows the lower reaches of Muir Glacier, then a large, tidewater calving valley glacier and its tributary, Riggs Glacier. For nearly two centuries before 1941, Muir Glacier had been retreating. In places, a t...

29

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)

30

Reconstructing glaciers: Sedimentary sources, sinks and fingerprints  

NASA Astrophysics Data System (ADS)

Glaciers are natural systems that shape and influence their geological surroundings through erosion and redistribution of sediments and rocks from one place to another. Their presence are determined by the landscape, regional climatic parameters such as wind, precipitation and temperature, and for these reasons they are valuable proxies of present and past climatic change. During the last four decades researchers have attempted to develop and assess methods that reliably and accurately reproduce continuous glacier variability over timescales extending thousands of years back in time. At the core of this multi-disciplinary endeavour is a strong desire to enhance our knowledge about how glaciers respond to a wider spectre of climatic change beyond what has been observed and documented for the last ~100 years. By far the majority of existing continuous glacier reconstructions are based on empirical evidence derived from soft sediment archives - mainly from lakes and fjords - making it quintessential to understand the sedimentary sources and sinks operating in glacierized catchment systems. If paleoclimatic inferences are to be made from such glacier reconstructions it is imperative that relevant sources of noise is considered, identified and, preferentially, eliminated. Here we review some of the problems and prospects of reconstructing temperate mountain or cirque glaciers as well as basic assumptions underlying most continuous glacier reconstructions. We will illustrate this challenge by presenting new data from a glacierized catchment surrounding a small lake called Blvatnet located in Northern Norway at 68N. A suit of piston and short gravity cores from the lake have been analysed and the results have been tested and corroborated by catchment samples from different sedimentary sources - an approach that is deemed to be of critical value when it comes to fingerprinting the glacier signal. Methodological emphasis is put on rock magnetism, which we demonstrate to be exceptionally well suited for identifying different sedimentary sources and characteristics typical for glacierized catchments. High sedimentation rates allow for a decadal glacier reconstruction covering the last 4000 years. Specifically, we observe major fluctuations in glacier activity that corresponds to an Equilibrium-Line-Altitude (ELA) variability of +/- 100 m. Peak activity is associated with the 'Little Ice Age' (1400-1800 AD) and a Neoglacial Maximum which occurred around 2500 years ago.

Paasche, O.; Lovlie, R.; Bakke, J.; Hirt, A. M.

2012-12-01

31

Pine Island Glacier  

Atmospheric Science Data Center

article title: Pine Island Glacier, Antarctica View Larger Image ... (MISR) images of the Pine Island Glacier in western Antarctica was acquired on December 12, 2000 during Terra orbit 5246. At left ...

2013-04-16

32

All About Glaciers  

NSDL National Science Digital Library

This National Snow and Ice Data Center's site contains information for wide range of audiences from glaciologists to grade school students. Data and Science offers links to glacier research, projects, and glaciological organizations online. Another section offers glacier facts, questions and answers, a glossary, a photo gallery, bibliography and links to glacier information on the web. Recent global newsworthy events are chronicled, and a tutorial offering a quick tour through the life of a glacier is available.

Armstrong, Richard

33

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.

34

The World Glacier Inventory  

NSDL National Science Digital Library

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

C. Haggerty

35

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

36

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

37

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.

38

Glaciers and Climate Change  

Microsoft Academic Search

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

J. Oerlemans

2001-01-01

39

The thermophysics of glaciers  

SciTech Connect

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

Zotikov, I.A.

1986-01-01

40

Glaciers and Icebergs  

NSDL National Science Digital Library

This lesson plan provides instruction to teachers for creating a glacier in the classroom to demonstrate how glaciation affects landforms. Learning objectives include student understanding that as glaciers move, they create a variety of patterns on landforms by a process called glacial scraping, that the scraping patterns left by a glacier depend on how the glacier moved over the landform, and that the evidence of glaciation left by glacial scraping provides clues to the climate in a particular place over a long period of time. The site also includes relevant vocabulary words with sound recordings for pronunciation. There are ideas presented for more advanced activities, discussion questions, and additional sources to consult.

Frank Weisel

41

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

42

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

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

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

43

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

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

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

44

Mini Glacier Meltdown  

NSDL National Science Digital Library

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

Twin Cities Public Television, Inc.

2007-01-01

45

The GLIMS Glacier Database  

Microsoft Academic Search

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 \\

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

2007-01-01

46

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 ...

47

Glaciers and Rocks  

NSDL National Science Digital Library

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

Jessica Fries-Gaither

48

Denali Fault: Susitna Glacier  

USGS Multimedia Gallery

Helicopters and satellite phones were integral to the geologic field response. Here, Peter Haeussler is calling a seismologist to pass along the discovery of the Susitna Glacier thrust fault. View is to the north up the Susitna Glacier. The Denali fault trace lies in the background where the two lan...

2008-12-15

49

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.

50

National Park Glaciers Knowledge Center  

NSDL National Science Digital Library

This interactive resource explains what glaciers are, where they are found, how they form, and how they move. The types and parts of glaciers are discussed, as well as ice ages, the different types of landforms that may result from glaciation, and how scientists monitor glaciers. Examples from our national parks are also highlighted as case studies to illustrate how glaciers have created landscapes.

2005-08-01

51

Air temperature variability over three glaciers in the Ortles-Cevedale (Italian Alps): effects of glacier disintegration, intercomparison of calculation methods, and impacts on mass balance modeling  

NASA Astrophysics Data System (ADS)

Glacier mass balance models rely on accurate spatial calculation of input data, in particular air temperature. Lower temperatures (the so-called glacier cooling effect), and lower temperature variability (the so-called glacier damping effect) generally occur over glaciers, compared to ambient conditions. These effects, which depend on the geometric characteristics of glaciers and display a high spatial and temporal variability, have been mostly investigated on medium- to large-size glaciers so far, while observations on smaller ice bodies are scarce. Using a dataset from 8 on-glacier and 4 off-glacier weather stations, collected in summer 2010 and 2011, we analyzed the air temperature variability and wind regime over three different glaciers in the Ortles-Cevedale. The magnitude of the cooling effect and the occurrence of katabatic boundary layer (KBL) processes showed remarkable differences among the three ice bodies, suggesting the likely existence of important reinforcing mechanisms during glacier decay and disintegration. None of the methods proposed in the literature for calculating on-glacier temperature from off-glacier data fully reproduced our observations. Among them, the more physically-based procedure of Greuell and Bhm (1998) provided the best overall results where the KBL prevail, but it was not effective elsewhere (i.e. on smaller ice bodies and close to the glacier margins). The accuracy of air temperature estimations strongly impacted the results from a mass balance model which was applied to the three investigated glaciers. Most importantly, even small temperature deviations caused distortions in parameter calibration, thus compromising the model generalizability.

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

2014-12-01

52

Do Glaciers on Cascade Volcanoes Behave Differently Than Other Glaciers in the Region?  

NASA Astrophysics Data System (ADS)

It has been suggested that glaciers on two stratovolcanoes in the Cascade Range of Washington state, Mt. Baker and Glacier Peak, achieved their maximum extent of the past 10,000 years during the early Holocene. These findings differ from most evidence in western North America, which indicates that Little Ice Age moraines represent the most extensive glacier advances of the Holocene. Significant early Holocene advances are difficult to reconcile with the documented warm, dry conditions at this time in western North America. Our data indicate that glaciers on these volcanoes responded similarly to Holocene climatic events as glaciers in other areas in Washington and British Columbia. Heavy winter accumulation and favorable hypsometry have been proposed as the explanations for the unusual behavior of glaciers on volcanoes compared to similar-sized glaciers elsewhere in the Cascade Range. However, glacier mass balance on the volcanoes is controlled by not only these factors, but also by glacier geometry, snow erosion and ablation. Accumulation zones of glaciers on isolated Cascade stratovolcanoes are high, but are narrow at the top. For example, the accumulation zone of Deming Glacier on the southwest side of Mt. Baker extends above 3000 m asl, but due to its wedge shape lies largely below 2500 m asl. Furthermore, glaciers on Mt. Baker and other symmetrical volcanoes have high ablation rates because they are not shaded, and south-southwest aspects are subject to erosion of snow by prevailing southwesterly winds. Modern glacier observations in the North Cascades quantify the important influence of aspect and snow erosion on glacier mass balance. For example, average equilibrium line altitude (ELA) of Easton Glacier on the south flank of Mt. Baker is 2160 m, whereas the ELA of a north-facing cirque glacier 25km to the east is 2040m. Our research at Mt. Baker contradicts the claim of extensive early Holocene advances on the south flank of the volcano. Tephra set SC, which has been radiocarbon dated to about 8850 14C yr old, is found on ridges that were previously mapped as moraines younger than the tephra. This relation indicates that "early Holocene" ridges are more than 8850 14C yr old, with their maximum age unconstrained. Most of the radial ridges previously mapped as moraines cannot be conclusively shown to be moraines; they could be lahar levees or diamict-covered bedrock ridges, which are common on Cascade stratovolcanoes. Our data indicate that the record of middle and late Holocene glaciation on Mt. Baker is similar, if not identical, to that reported from the British Columbia Coast Mountains. Consequently, there is no reason to believe that the history of Holocene glaciation on Cascade volcanoes is radically different than elsewhere in western North America.

Riedel, J. L.; Ryane, C.; Osborn, J.; Davis, T.; Menounos, B.; Clague, J. J.; Koch, J.; Scott, K. M.; Reasoner, M.

2006-12-01

53

Wind  

NSDL National Science Digital Library

What part does the wind play in satisfying energy demands? This informational piece, part of a series about the future of energy, introduces students to wind as an energy source. Here students read about the history, uses, and efficiency of wind power. Information is also provided about benefits, limitations, and geographical considerations of wind power in the United States. Thought-provoking questions afford students chances to reflect on what they've read about the uses of wind power. Supplemental articles and information are available from a sidebar. Three energy-related web links are also provided. Copyright 2005 Eisenhower National Clearinghouse

Iowa Public Television. Explore More Project

2004-01-01

54

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.

55

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

56

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

57

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

58

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

59

Getting the Shot, Grinnell Glacier, Glacier National Park.  

USGS Multimedia Gallery

USGS scientist shoots a repeat photograph of Grinnell Glacier in Glacier National Park to illustrate glacial recession due to impacts of climate change. *note logo on scientists hat is logo from USGS Northern Rocky Mountain Science Center, not private....

60

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

61

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

62

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

63

Glacier mass-balance standards  

Microsoft Academic Search

Deep-sea cores and ice cores from the late Cenozoic show that the Earth's climate changes significantly. Glacier fluctuations are but one indication of this change. Glaciers are both an active component of the environmental system, regulating mountain streamflow, and a passive one, responding to climatic change. Thus, an understanding of the link between climate and glaciers is needed in order

A. G. Fountain; D. Trabant; M. M. Brugman; C. S. L. Ommanney; S. Monroe

1991-01-01

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Engineering geomorphology of rock glaciers  

NASA Astrophysics Data System (ADS)

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

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

1999-12-01

65

Methods of Measuring Glacier Change  

Microsoft Academic Search

In the 19th century measuring glacier change was limited to measuring the position of the glacier front, or terminus. By the mid 20th century, change measurements expanded to include aerial photogrammetry and field-based mass balance methods. The latter were typically based on stakes drilled into a glacier, against which snow accumulation and ice loss were measured. Knowing the density of

A. G. Fountain

2001-01-01

66

Denali Fault: Black Rapids Glacier  

USGS Multimedia Gallery

View eastward along Black Rapids Glacier. The Denali fault follows the trace of the glacier. These very large rockslides went a mile across the glacier on the right side. Investigations of the headwall of the middle landslide indicate a volume at least as large as that which fell, has dropped a mete...

2008-12-15

67

Iceland Glacier Recession 1973 to 2000, Glacier Terminus contrast emphasized  

NSDL National Science Digital Library

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

Perkins, Lori; Hall, Dorothy

2001-04-09

68

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

69

Northern Illinois University: Glaciers  

NSDL National Science Digital Library

Northern Illinois University offers illustrative summary of glaciers and glacial processes. The website provides a timeline of the glacial advances into Illinois. Students and educators can learn a few of the landscape features that scientists use to interpret geologic history. Users can learn how glaciers affected Illinois's topography and waterbodies. The site furnishes educational maps of Illinois's bedrock geology and shaded relief. The text is linked to a glossary to assist users with glacial terminology. While this website does concentrate on the state of Illinois, everyone can learn basic characteristics of glacial movements.

70

A Disintegrating Glacier  

NSDL National Science Digital Library

Recent satellite images have revealed two new icebergs floating off the Antarctic coast. The icy behemoths are fragments of the Ninnis Glacier. This NASA fact sheet uses text and remotely sensed imagery to describe the events of January 2000, in which a large tongue of the Ninnis Galcier broke off and split into two gigantic icebergs. The breakup of the Ninnis Glacier Tongue has important implications regarding the Antarctic Ice Sheet's potential response to global climate change and its effect on global sea level. Links to other related sites are also included.

2000-12-06

71

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

72

Glacier Goo Erosion Experiments  

NSDL National Science Digital Library

Using a glacier proxy, students design an experiment to connect glacial erosion with glacial flow. Students choose from a variety of materials, determined what question they want their experiment or experiments to answer, design the procedure, test the experiment, and write up a lab report on the experiment.

Rachel Headley

73

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

74

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

75

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

76

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

77

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

78

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

NSDL National Science Digital Library

This animated model shows the predicted effects of glacial melting and changes in vegetation patterns in the Blackfoot-Jackson Glacier Basin of Glacier National Park, Montana. The scenario incorporated in the model consists of a predicted exponential rise in atmospheric CO2 concentrations, a 2xCO2 global warming scenario, with a concurrent warming of 2-3 degrees centigrade (4-5 degrees Fahrenheit) by the year 2050. In addition, it assumes that precipitation, primarily in the form of rain, will increase over the same time period about 10 percent. The animation is accompanied by a set of still images displaying intermediate steps used in the calculations of the ecological components, such as terrain characteristics, sun impact, soil moisture, and wind.

Dan Fagre

2003-01-01

79

Icefall on the Lambert Glacier  

NASA Technical Reports Server (NTRS)

The Lambert Glacier in Antarctica is the world's largest glacier. The focal point of this image is an icefall that feeds into the Lambert glacier from the vast ice sheet covering the polar plateau. Ice flows like water, albeit much more slowly. Cracks can be seen in this icefall as it bends and twists on its slow-motion descent 1300 feet (400 meters) to the glacier below. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on December 2, 2000. This is a false-color composite image made using infrared, red, and green wavelengths. The image has also been sharpened using the sensor's panchromatic band.

2002-01-01

80

Mass balance model parameter transferability on a tropical glacier  

NASA Astrophysics Data System (ADS)

The mass balance and melt water production of glaciers is of particular interest in the Peruvian Andes where glacier melt water has markedly increased water supply during the pronounced dry seasons in recent decades. However, the melt water contribution from glaciers is projected to decrease with appreciable negative impacts on the local society within the coming decades. Understanding mass balance processes on tropical glaciers is a prerequisite for modeling present and future glacier runoff. As a first step towards this aim we applied a process-based surface mass balance model in order to calculate observed ablation at two stakes in the ablation zone of Shallap Glacier (4800 m a.s.l., 9S) in the Cordillera Blanca, Peru. Under the tropical climate, the snow line migrates very frequently across most of the ablation zone all year round causing large temporal and spatial variations of glacier surface conditions and related ablation. Consequently, pronounced differences between the two chosen stakes and the two years were observed. Hourly records of temperature, humidity, wind speed, short wave incoming radiation, and precipitation are available from an automatic weather station (AWS) on the moraine near the glacier for the hydrological years 2006/07 and 2007/08 while stake readings are available at intervals of between 14 to 64 days. To optimize model parameters, we used 1000 model simulations in which the most sensitive model parameters were varied randomly within their physically meaningful ranges. The modeled surface height change was evaluated against the two stake locations in the lower ablation zone (SH11, 4760m) and in the upper ablation zone (SH22, 4816m), respectively. The optimal parameter set for each point achieved good model skill but if we transfer the best parameter combination from one stake site to the other stake site model errors increases significantly. The same happens if we optimize the model parameters for each year individually and transfer these combinations to the other year. We show that multi-site and multi-year analyses are crucial before extrapolating ablation modeling to larger glacier areas. So far tested surface albedo schemes and respective parameterizations can obviously not satisfyingly reproduce the dynamics of glacier surface conditions at our study site and new solutions to the problem have to be explored.

Gurgiser, Wolfgang; Mlg, Thomas; Nicholson, Lindsey; Kaser, Georg

2013-04-01

81

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.

82

Secular glacier mass balances derived from cumulative glacier length changes  

Microsoft Academic Search

Glacier mass changes are considered to represent natural key variables with respect to strategies for early detection of enhanced greenhouse effects on climate. The main problem, however, with interpreting worldwide glacier mass balance evolution concerns the question of representativity. One important key to deal with such uncertainties and to assess the spatio-temporal representativity of the few available measurements is the

M. Hoelzle; W. Haeberli; M. Dischl; W. Peschke

2003-01-01

83

Listening to Glaciers: Passive hydroacoustics near marine-terminating glaciers  

USGS Publications Warehouse

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

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

2012-01-01

84

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

85

ASTER Image of Gangotri Glacier  

USGS Multimedia Gallery

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

86

Chernobyl fallout on Alpine glaciers  

SciTech Connect

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

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

1989-01-01

87

1, 1739, 2007 Glacier balance  

E-print Network

TCD 1, 17­39, 2007 Glacier balance measurement, forecasting M. S. Pelto Title Page Abstract The Cryosphere Discussions is the access reviewed discussion forum of The Cryosphere Glacier annual balance balance measurement, forecasting M. S. Pelto Title Page Abstract Introduction Conclusions References

Paris-Sud XI, Université de

88

Pine Island Glacier Calving (WMS)  

NSDL National Science Digital Library

The Pine Island Glacier is the largest discharger of ice in Antarctica and the continents fastest moving glacier. Even so, when a large crack formed across the glacier in mid 2000, it was surprising how fast the crack expanded, 15 meters per day, and how soon the resulting iceberg broke off, mid-November, 2001. This iceberg, called B-21, is 42 kilometers by 17 kilometers and contains seven years of glacier outflow released to the sea in a single event. This series of images from the MISR instrument on the Terra satellite not only shows the crack expanding and the iceberg breakoff, but the seaward moving glacial flow in the parts of the Pine Island Glacier upstream of the crack.

Perkins, Lori; Mitchell, Horace; Bindschadler, Bob; Diner, Dave

2005-03-09

89

Malaspina Glacier, Alaska  

NASA Technical Reports Server (NTRS)

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

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

ASTER is one of five Earth-observing instruments launched December 18,1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. science team leader; Bjorn Eng of JPL is the project manager. ASTER is the only high-resolution imaging sensor on Terra. The Terra mission is part of NASA's Earth Science Enterprise, along-term research and technology program designed to examine Earth's land, oceans, atmosphere, ice and life as a total integrated system.

The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

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

2001-01-01

90

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

91

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

92

Instructions for Glacier Recession Lesson Objective: Students will learn  

E-print Network

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

93

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

94

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

95

Increased glacier runoff enhances the penetration of warm Atlantic Water into a large Greenland fjord  

NASA Astrophysics Data System (ADS)

The retreat and acceleration of Greenland's marine-terminating outlet glaciers have been linked to ocean warming. However the mechanisms which control the transmission of this warming along fjords towards the glacier termini remain poorly understood. Here we aim to elucidate observed changes in water properties in Kangerdlugssuaq Fjord (KF), east Greenland, between 1993 and 2004 using the Bergen Ocean Model (BOM). Model outputs are compared with observed potential temperature, salinity and velocity data to determine the principal controls on heat transport within KF. The BOM includes wind, tidal and glacier runoff forcing and is able to replicate observed temperature and salinity profiles. Model results describe a robust four-layer estuarine flow, consisting of two distinct circulations. The shallow circulation (0 - 60 m) is forced by surface wind stress and to a lesser extent supraglacial runoff, while the intermediate circulation (60 - 500 m) is driven by runoff discharged into the fjord subglacially. AtlanticWater (AW) and warm Polar Surface Water (PSWw) are drawn into the fjord by the intermediate and shallow circulation cells respectively, in a pattern consistent with observations, and AW reaches Kangerdlugssuaq Glacier (at the fjord head) over a single summer. Along-fjord heat transport towards KG increases significantly with both glacier runoff and coastal water temperature. A doubling of glacier runoff produces a 29 % (48 %) amplification of mean annual (summer) heat transport towards the KG terminus. Our model shows, in agreement with observations, that maximum submarine melt rates occur when AW and PSWw are present at the fjord mouth and, crucially, glacier runoff is also high. Rising ice sheet runoff therefore increases the sensitivity of KG (and other Greenland marine-terminating glaciers) to ocean warming.

Sole, Andrew; Payne, Anthony; Nienow, Peter; Christoffersen, Poul; Cottier, Finlo; Inall, Mark

2013-04-01

96

Seaonalities of glacier changes on the polythermal glaciers, Nyainqntanglha Range  

NASA Astrophysics Data System (ADS)

The climatic variables are supposed to be the influential factors for the summer accumulation type glaciers in the Nyainqntanglha Range, Tibetan Plateau. There are certainly unique regional climate regimes within this area during different seasons. In the summer season, the prevailing regional climate is controlled by a plenty of moisture transported by the warm summer monsoons, while it is getting colder and drier by the westerlies from the inland of Eurasia in the winter season. The impact of the resultant local hydro-thermal condition fluctuation on the the glacier dynamics is still not well understood. In this study, the seasonal patterns of glacier behaviors are estimated in terms of glacier surface displacements under a certain climatological state (2006-2009). The glacier surface displacements are derived from Landsat imageries by using the feature tracking method. The land surface temperatures and precipitations are selected as the representative parameters of the regional climate in the Nyainqntanglha Range. According to the tendency analysis, the apparent annual cycle of precipitation and land surface temperature are recognized. At the same time, the diurnal change of land surface temperature (>0C mostly in the daytime,

Shi, Junchao; Menenti, Massimo

2014-05-01

97

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

Microsoft Academic Search

Equilibrium-line altitudes (ELAs) of modem glaciers in the northern Rocky Mountains are known to correspond with regional climate, but strong subregional gradients such as across the Continental Divide in Glacier National Park, Montana, also exert topoclimatic influences on the ELA. This study analyzed the relationships between glacier and snowfield morphology, ELA, and surrounding topography. Glaciers and perennial snowfields were mapped

Thomas R. Allen

1998-01-01

98

Aletsch Glacier, Switzerland  

NASA Technical Reports Server (NTRS)

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

This image was acquired on July 23, 2001 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet. ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

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

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

2002-01-01

99

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

100

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

101

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

102

Glacier Mass Balance measurements in Bhutan  

NASA Astrophysics Data System (ADS)

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

Jackson, Miriam; Tenzin, Sangay; Tashi, Tshering

2014-05-01

103

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

104

Glaciers and icecaps: Storehouses of freshwater  

NSDL National Science Digital Library

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

2008-05-28

105

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....

106

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

107

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

USGS Publications Warehouse

During the summer of 1984 and 1985, laser measurements were made of the distance from a reference location to markers on the surface of the lower reach of Columbia Glacier, Alaska. The speed varies from 7 to 15 m/d and has three noteworthy components: 1) a low-frequency perturbation in speed with a time scale of days related to increased precipitation, 2) semidiurnal and diurnal variations related to sea tides, and 3) diurnal variations related to glacier surface melt. -from Authors

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

1987-01-01

108

The effect of glaciers on streamflow variations.  

USGS Publications Warehouse

The effect of temperate glaciers on runoff variations is examined for the North Cascade Mountains of Washington State. An algorithm is presented that calculates the coefficient of variation of runoff for any arbitrary glacier cover. The results suggest that a minimum in year-to-year variation occurs for basins about 36% glacierized. On a month-to-month basis, maximum variation occurs in July and August for basins with less than 10% glacier cover but is a minimum for basins with glacier covers greater than 30%. -from Authors

Fountain, A.G.; Tangborn, W.V.

1985-01-01

109

Glacier recession in Iceland and Austria  

SciTech Connect

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

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

1992-03-01

110

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

111

Light Iceland Glacier Recession 1973 to 2000  

NSDL National Science Digital Library

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

Perkins, Lori; Hall, Dorothy

2001-04-09

112

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

113

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

114

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

115

The status of glaciers in Sikkim Himalaya  

NASA Astrophysics Data System (ADS)

This study focuses on the influence of lakes and debris cover on the glacier area changes, in the data scarce Sikkim Himalayas, between 1990 and 2010, using Landsat TM and IRS images. A new technique of estimating 'interpretation uncertainty' while mapping glacier terminus on satellite images, is introduced. The overall study showed (i) a glacier area loss of 3 0.8 % in 20 years. We also observed the presence of lakes on many debris-covered glaciers, and its expansion accelerated the glacier retreat by 9 1.4 %. Though some 'debris-covered glaciers' showed stable fronts, the gradual development and coalescence of supraglacial lakes led to the formation of moraine dam lakes at the terminus. This investigation suggests that 'debris cover' on glaciers can enhance the development of glacial lakes. As a consequence, the retreat of debris-covered glaciers associated with lakes is clearly higher than that of debris-free glaciers. Location of glacier in Sikkim. The map shows the location of glaciers studied in this investigation. : Evolution and coalescence of a supra glacial lake and the formation of a moraine dam. Figs. a and b show no frontal change between 1990 and 1997. Fig. b shows the evolution of a supraglacial lake and fig. c shows the coalescence of supraglacial lake, which occupies glacier area between two lateral moraines. Fig. d shows the formation of a moraine dam lake leading to glacierarea loss.(The yellow line represents the glacier boundary for the year 1990; and red line is the glacier terminus for the year 2009). The four imagesused is a false colour composite with a band combination of red, NIR and SWIR.

basnett, S.; Kulkarni, A. V.; Bolch, T.

2013-12-01

116

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

117

Mountain Glaciers and Ice Caps  

USGS Publications Warehouse

Projections of future rates of mass loss from mountain glaciers and ice caps in the Arctic focus primarily on projections of changes in the surface mass balance. Current models are not yet capable of making realistic forecasts of changes in losses by calving. Surface mass balance models are forced with downscaled output from climate models driven by forcing scenarios that make assumptions about the future rate of growth of atmospheric greenhouse gas concentrations. Thus, mass loss projections vary considerably, depending on the forcing scenario used and the climate model from which climate projections are derived. A new study in which a surface mass balance model is driven by output from ten general circulation models (GCMs) forced by the IPCC (Intergovernmental Panel on Climate Change) A1B emissions scenario yields estimates of total mass loss of between 51 and 136 mm sea-level equivalent (SLE) (or 13% to 36% of current glacier volume) by 2100. This implies that there will still be substantial glacier mass in the Arctic in 2100 and that Arctic mountain glaciers and ice caps will continue to influence global sea-level change well into the 22nd century.

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

2011-01-01

118

Icebergs and Glaciers: Unit Outlines  

NSDL National Science Digital Library

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

Jessica Fries-Gaither

119

Response of debris-covered glaciers to climate change  

Microsoft Academic Search

The presence of supraglacial debris strongly influences glacier ablation, and the mass balance of debris-covered glaciers differs significantly from that of clean glaciers in similar climatic settings. Predicting the response of debris-covered glaciers to climate change is important for hazard mitigation strategies in many high mountain environments, especially where temporary lakes are likely to form on stagnating glacier tongues. Accurate

D. I. Benn; N. Lindsey; H. Kathryn

2004-01-01

120

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

121

Muir and Riggs Glaciers, Muir Inlet, Alaska - 1941  

USGS Multimedia Gallery

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

122

Glacial Change in the Wind River Range, Wyoming, USA  

Microsoft Academic Search

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

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

2007-01-01

123

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

124

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

Microsoft Academic Search

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

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

2009-01-01

125

GLACIER HAZARDS AT BELVEDERE GLACIER AND THE MONTE ROSA EAST FACE, ITALIAN ALPS: PROCESSES AND MITIGATION  

E-print Network

are extending towards danger zones in the cryospheric systems. A number of recent glacier hazards and disasters particularly affects terrestrial systems where surface and sub-surface ice is involved. Changes in glacier

Kääb, Andreas

126

Supraglacial lakes on Himalayan debris-covered glacier (Invited)  

NASA Astrophysics Data System (ADS)

Debris-covered glaciers are common in many of the world's mountain ranges, including in the Himalayas. Himalayan debris-covered glacier also contain abundant glacial lakes, including both proglacial and supraglacial types. We have revealed that heat absorption through supraglacial lakes was about 7 times greater than that averaged over the whole debris-covered zone. The heat budget analysis elucidated that at least half of the heat absorbed through the water surface was released with water outflow from the lakes, indicating that the warm water enlarge englacial conduits and produce internal ablation. We observed some portions at debris-covered area has caved at the end of melting season, and ice cliff has exposed at the side of depression. Those depression has suggested that roof of expanded water channels has collapsed, leading to the formation of ice cliffs and new lakes, which would accelerate the ablation of debris-covered glaciers. Almost glacial lakes on the debris-covered glacier are partially surrounded by ice cliffs. We observed that relatively small lakes had non-calving, whereas, calving has occurred at supraglacial lakes with fetch larger than 80 m, and those lakes expand rapidly. In the Himalayas, thick sediments at the lake bottom insulates glacier ice and lake water, then the lake water tends to have higher temperature (2-4 degrees C). Therefore, thermal undercutting at ice cliff is important for calving processes in the glacial lake expansion. We estimated and subaqueous ice melt rates during the melt and freeze seasons under simple geomorphologic conditions. In particular, we focused on valley wind-driven water currents in various fetches during the melt season. Our results demonstrate that the subaqueous ice melt rate exceeds the ice-cliff melt rate above the water surface when the fetch is larger than 20 m with the water temperature of 2-4 degrees C. Calculations suggest that onset of calving due to thermal undercutting is controlled by water currents driven by winds at the lake surface with a positive feedback process. The risk of GLOFs (glacial lake outburst flood) are analysed for Himalayan glacial lakes. We proposed an objective index for GLOF probability, based on depression angle from the lakeshore, which allows the lakes to be assessed using remotely sensed digital elevation models (DEMs). The index was verified by pre-GLOF topography derived by spy satellite imageries. We screened 2800 Himalayan glacial lakes and identified 49 lakes with potential flood volumes over 10 million m3.

Sakai, A.; Fujita, K.

2013-12-01

127

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

128

1. PARKING LOT AT GLACIER POINT. HALF DOME AT CENTER ...  

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

1. PARKING LOT AT GLACIER POINT. HALF DOME AT CENTER REAR. LOOKING NE. GIS: N-36 43 45.8 / W-119 34 14.1 - Glacier Point Road, Between Chinquapin Flat & Glacier Point, Yosemite Village, Mariposa County, CA

129

5. GLACIER POINT ROAD VIEW AT SENTINEL DOME PARKING AREA. ...  

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

5. GLACIER POINT ROAD VIEW AT SENTINEL DOME PARKING AREA. LOOKING E. GIS: N-37 42 43.8 / W-119 35 12.1 - Glacier Point Road, Between Chinquapin Flat & Glacier Point, Yosemite Village, Mariposa County, CA

130

Calendar-dated, early 'Little Ice Age' glacier advance at Robson Glacier, British Columbia, Canada  

Microsoft Academic Search

Dendrochronological studies at Robson and Bennington Glaciers have provided the first calendar dating of an early 'Little Ice Age' glacier advance in North America. Dates derived from in-situ stumps indicate that Robson Glacier began over-riding forest between c. AD 1142 and 1150 and continued until at least AD 1350. The highest rates of glacier advance (c. 3.8 m yr-1 )

B. H. Luckman

1995-01-01

131

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

132

Attribution of glacier fluctuations to climate change  

NASA Astrophysics Data System (ADS)

Glacier retreat is a worlwide phenomenon, which started around the middle of the 19th century. During the period 1800-1850 the number of retreating and advancing glaciers was roughly equal (based on 42 records from different continents). During the period 1850-1900 about 92% of all mountain glaciers became shorter (based on 65 records). After this, the percentage of shrinking glaciers has been around 90% until the present time. The glacier signal is rather coherent over the globe, especially when surging and calving glaciers are not considered (for such glaciers the response to climate change is often masked by length changes related to internal dynamics). From theoretical studies as well as extensive meteorological work on glaciers, the processes that control the response of glaciers to climate change are now basically understood. It is useful to make a difference between geometric factors (e.g. slope, altitudinal range, hypsometry) and climatic setting (e.g. seasonal cycle, precipitation). The most sensitive glaciers appear to be flat glaciers in a maritime climate. Characterizing the dynamic properties of a glacier requires at least two quantities: the climate sensitivity, expressing how the equilibrium glacier state depends on the climatic conditions, and the response time, indicating how fast a glacier approaches a new equilibrium state after a stepwise change in the climatic forcing. These quantities can be estimated from relatively simple theory, showing that differences among glaciers are substantial. For larger glaciers, climate sensitivities (in terms of glacier length) vary from 1 to 8 km per 100 m change in the equilibrium-line altitude. Response times are mainly in the range of 20 to 200 years, with most values between 30 and 80 years. Changes in the equilibrium-line altitude or net mass balance of a glacier are mainly driven by fluctuations in air temperature, precipitation, and global radiation. Energy-balance modelling for many glaciers shows that, globally speaking, a 1 K temperature increase has the same effect as a ~25% decrease in precipitation, or a ~15% increase in global radiation. However, the relative importance of these drivers depends significantly on the climatic setting (notably continentality). In this contribution I will give a brief survey of glacier fluctuations over the past few centuries, and provide arguments that on the worldwide scale air temperature must have been the main driver of these fluctuations. A history of global mean temperature that explains the observed glacier fluctuations best will be discussed. On smaller spatial (regional) and temporal (decades) scales, changes in precipitation become important. Both with respect to the attribution problem (what caused the glacier fluctuations in the past?) and the projection issue (what will happen in the next 100 years?), it is important that many more glaciers are explicitly studied with numerical models. I will argue that for non-calving glaciers these models can be relatively simple.

Oerlemans, J.

2012-04-01

133

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

134

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

135

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

136

Mass-balance characteristics of arctic glaciers  

Microsoft Academic Search

A survey of available mass-balance data shows that glaciers on arctic islands, i.e. mountain glaciers and ice caps in northern Canada, Greenland, Svalbard and the Eurasian islands, share mass-balance characteristics of low annual amplitude and small interannual variability. By contrast, glaciers around the Arctic (e.g. in Alaska, Iceland, mainland Scandinavia and northern Eurasia) can have exceptionally large annual amplitude and

Roger J. Braithwaite

2005-01-01

137

Glac Modeled Glacier Change Animation  

NSDL National Science Digital Library

Animation of Modeled Climate-Induced Glacier Change in Glacier National Park, 1850- 2100. The simulation reflects the predicted exponential rise in atmospheric CO2 concentrations, a 2xCO2 "global warming" scenario, with a concurrent warming of 2-3 degrees centigrade (4-5 degrees Fahrenheit) by the year 2050. In addition it assumes that precipitation, primarily in the form of rain, will increase over the same time period about 10 percent (based on the research of Dr. Steven Running, University of Montana). The animation view of the Blackfoot-Jackson basin along the Continental Divide, includes Gunsight Lake in the foreground and a portion of Lake Ellen Wilson visible over Gunsight Pass.

Myrna H. P. Hall

138

Fluffy Snow to Glacier Ice  

NSDL National Science Digital Library

In this activity, students build on their growing knowledge of ice and glacier growth. The students examine images of core samples and make observations about the decreasing size of gas bubbles with increasing depth in the core. The students model permeability. From this experiment, they will develop an understanding of the movement of air through snow and ice and why this information is critical to researchers studying the past climate of our Earth.

Sharon Shutey

139

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

140

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

141

Increased glacier runoff enhances the penetration of warm Atlantic water into a large Greenland fjord  

NASA Astrophysics Data System (ADS)

The retreat and acceleration of Greenland's marine-terminating outlet glaciers have been linked to ocean warming. However the mechanisms which control the transmission of this warming along fjords towards the glaciers remain poorly understood. The aim of this paper is to elucidate observed changes in water properties in Kangerdlugssuaq Fjord (KF), East Greenland using the Bergen Ocean Model (BOM). Model outputs are compared with observed potential temperature, salinity and velocity data to determine the principal controls on heat transport within KF and to estimate resulting submarine ice front melt rates of Kangerdlugssuaq Glacier (KG). The BOM includes wind, tidal and glacier runoff forcing and is able to replicate observed temperature and salinity profiles. Model results describe a robust four-layer estuarine flow, consisting of two distinct circulations. The shallow circulation (0-~ 60 m) is forced by surface wind stress and to a lesser extent supraglacial runoff, while the intermediate circulation (~ 60-500 m) is driven by runoff discharged into the fjord subglacially. Atlantic Water (AW) and warm Polar Surface Water (PSWw) are drawn into the fjord by the intermediate and shallow circulation cells respectively, in a pattern consistent with observations, and AW reaches KG over a single summer. Along-fjord heat transport towards KG increases significantly with both glacier runoff and coastal water temperature. A doubling of glacier runoff produces a 29% (48%) amplification of mean annual (summer) heat transport towards the KG terminus, increasing estimated mean annual (summer) submarine melt rates from 211 to 273 (842 to 1244) m yr-1. In contrast, heat transport towards KG in the surface ~ 60 m of the fjord decreases with rising glacier runoff because the enhanced down-fjord component of the intermediate circulation interferes with the up-fjord part of the shallow circulation. Thus, as ice sheet runoff increases, KG's dynamic response to oceanic forcing will likely be driven primarily by enhanced submarine ice front melting and consequent undercutting rather than through diminished buttressing from seasonal sea ice and ice mlange. Our model shows, in agreement with observations, that maximum submarine melt rates occur when AW and PSWw are present at the fjord mouth and, crucially, glacier runoff is also high. Rising ice sheet runoff therefore increases the sensitivity of KG (and other Greenland marine-terminating glaciers) to ocean warming.

Sole, A. J.; Payne, A. J.; Nienow, P. W.; Christoffersen, P.; Cottier, F. R.; Inall, M. E.

2012-11-01

142

Greenland glacier calving rates from Extreme Ice Survey (EIS) time lapse photogrammetry  

NASA Astrophysics Data System (ADS)

Time lapse cameras fill gaps in our observational capabilities: 1. By providing much higher temporal resolution than offered by conventional airborne or satellite remote sensing. 2. While GPS or auto-theodolite observations may provide valuable higher time resolution data than from photogrammetry, survival of these sensors on the hazardous glacier surface is limited and maintenance costs are high. 3. Imagery provide a high spatial density of observations across the glacier surface. 4. time lapse cameras provide observational capabilities in Eulerian and Lagrangian frames while GPS or theodolite targets, going along for a ride on the glacier, provide only Lagrangian data. Photogrammetry techniques are applied to a year-plus of images from multiple west Greenland glaciers to determine the glacier front calving rates and horizontal velocity at hourly to seasonal time scales. We present an analysis of calving rates versus various environmental factors including: sea and land surface temperature; near-surface air temperature; winds; tidal stage; and motion derived from in-situ GPS.

Jung, J.; Box, J. E.; Balog, J. D.; Ahn, Y.; Decker, D. T.; Hawbecker, P.

2010-12-01

143

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

144

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

145

Supplementary Material: Glacier melt contribution to streamflow  

E-print Network

variations in the surface mass balance of 18 Svalbard glaciers from the Moderate Resolution Imaging of direct mass balance of Hintereisferner. Global and Planetary Change, 71, 13-26. Greuell, W., Kohler, J, J.-E. and Carenzo, M. 2008. A study of the energy balance and melt regime on Juncal Norte Glacier

Washington at Seattle, University of

146

Recent acceleration of glacier thinning in Svalbard  

Microsoft Academic Search

Geodetic data comprising archive maps, contemporary lidar, and photogrammetric digital elevation models show that the rate of volume loss of two Svalbard glaciers, Midtre Lovnbreen (ML) and Slakbreen (SL), has accelerated in recent years. At ML, the thinning rate as averaged over the whole glacier has increased steadily over the latter part of the 20th century. The mean thinning rate

J. Kohler; T. D. James; T. Murray; C. Nuth; O. Brandt; N. E. Barrand; H. F. Aas; A. Luckman

2006-01-01

147

GLIMS: Progress in Mapping the World's glaciers  

Microsoft Academic Search

The Global Land Ice Measurements from Space (GLIMS) initiative has built a database of glacier outlines and related attributes, derived primarily from satellite imagery, such as from ASTER and Landsat. Each snapshot of a glacier is from a specific time, and the database is designed to store multiple snapshots representative of different times. The database currently contains outlines for approximately

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

2009-01-01

148

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

149

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,...

150

Glaciers in 21st Century Himalayan Geopolitics  

Microsoft Academic Search

Glaciers are ablating rapidly the world over. Nowhere are the rates of retreat and downwasting greater than in the Hindu Kush-Himalaya (HKH) region. It is estimated that over the next century, 40,000 square kilometers of present glacier area in the HKH region will become ice free. Most of this area is in major valleys and the lowest glaciated mountain passes.

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

2002-01-01

151

GLIMS Glacier Database: Status and Challenges  

Microsoft Academic Search

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

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

2008-01-01

152

Components: The GLIMS Geospatial Glacier Database  

E-print Network

Components: The GLIMS Geospatial Glacier Database http://glims.colorado.edu/glacierdata/ Bruce Raup Table of attributes in query results Map of query results Selected glacier is highlighted Political of GIS data formats. Planned enhancements to the database itself include increasing the volume of data

153

GIS-based glacier inventory of China  

Microsoft Academic Search

The project of the Glacier Inventory of China initialized in 1979 was just accomplished in 2000. This inventory was complied based on numerous LandSat TM images, aerial photographs, and topographic maps. More than 40 Chinese glaciologists made their great efforts in this work. With the newest statistics from the inventory, there are total 46,928 glaciers in China; the total area

X. Li; L.-Z. Wu

2003-01-01

154

Latest Pleistocene advance of alpine glaciers in the southwestern Uinta Mountains, Utah, USA: Evidence for the influence of local moisture sources  

Microsoft Academic Search

Cosmogenic surface-exposure Be-10 dating of Last Glacial Maximum (LGM) moraines indicates that glaciers in the southwestern Uinta Mountains remained at their maximum positions until ca. 16.8 +\\/- 0.7 ka, similar to 2 k.y. after glaciers in the neighboring Wind River Range and Colorado Rockies began to retreat. The timing of the local LGM in the southwestern Uintas overlaps with both

Jeffrey S. Munroe; Benjamin J. C. Laabs; Jeremy D. Shakun; Brad S. Singer; David M. Mickelson; Kurt A. Refsnider; Marc W. Caffee

2006-01-01

155

Iceland Glacier Recession 1997 to 2000  

NSDL National Science Digital Library

This animation is a close up zoom into largest area of glacier recesion at the Breidamerkurjokull glacier in Iceland. The data from 1997 is taken from Landsat 5 and the 2000 data is from Landsat 7. The Breidamerkurjokull glacier in Iceland has been measured by Landsat to be receding since 1973. In 1997, Landsat 5 took several other images of the glacier. It was thought by some glacierologists that this particular glacier was receding quicker in the late 1990s than it did in the late 1980s or 1970s. After careful analysis Goddards Glacierologist, Dorothy Hall, concluded that the recession from 1997 to 2000 occurs at a similar rate to the recession between 1973 and 2000. It is extremely controversial whether or not this recession is caused by global warming.

Perkins, Lori; Hall, Dorothy

2001-04-09

156

Glaciers in 21st Century Himalayan Geopolitics  

NASA Astrophysics Data System (ADS)

Glaciers are ablating rapidly the world over. Nowhere are the rates of retreat and downwasting greater than in the Hindu Kush-Himalaya (HKH) region. It is estimated that over the next century, 40,000 square kilometers of present glacier area in the HKH region will become ice free. Most of this area is in major valleys and the lowest glaciated mountain passes. The existence and characteristics of glaciers have security impacts, and rapidly changing HKH glaciers have broad strategic implications: (1) Glaciers supply much of the fresh water and hydroelectric power in South and Central Asia, and so glaciers are valuable resources. (2) Shared economic interests in water, hydroelectricity, flood hazards, and habitat preservation are a force for common cause and reasoned international relations. (3) Glaciers and their high mountains generally pose a natural barrier tending to isolate people. Historically, they have hindered trade and intercultural exchanges and have protected against aggression. This has further promoted an independent spirit of the region's many ethnic groups. (4) Although glaciers are generally incompatible with human development and habitation, many of the HKH region's glaciers and their mountains have become sanctuaries and transit routes for militants. Siachen Glacier in Kashmir has for 17 years been "the world's highest battlefield," with tens of thousands of troops deployed on both sides of the India/Pakistan line of control. In 1999, that conflict threatened to trigger all-out warfare, and perhaps nuclear warfare. Other recent terrorist and military action has taken place on glaciers in Kyrgyzstan and Tajikistan. As terrorists are forced from easily controlled territories, many may tend to migrate toward the highest ground, where definitive encounters may take place in severe alpine glacial environments. This should be a major concern in Nepali security planning, where an Army offensive is attempting to reign in an increasingly robust and brutal Maoist insurgency. (5) Glacier lakes are in many cases very fragile and their natural dams routinely rupture, causing devastating floods. A rising regional terrorist threat in several countries could target these dams and precipitate calamitous and terrifying results. (6) Over the next century, retreating glaciers may open new corridors for trade and human migration across the Himalaya and pave the way for possible new economic, military and political alliances in the region. (7) Glacier retreat might open new sanctuaries for terrorists and open new corridors for possible ground-based military offensive action across the HKH ranges. The documentation of glacier characteristics that may influence their trafficability, and projections of future glacier extent and behavior are relevant to wide ranging concerns of the region's inhabitants. Satellite remote sensing and mapping of glaciers is one approach to defining and monitoring the problems and opportunities presented by HKH glaciers. Global Land Ice Measurements from Space (GLIMS) is a joint USGS/NASA Pathfinder project that has formed a global consortium of glaciologists in several regional centers that are mapping and monitoring the HKH glaciers using repeat-pass ASTER and Landsat ETM+ data. We are currently building a comprehensive satellite multispectral image and GIS database that is providing detailed information on the state and rates of change of each glacier in the HKH region and other areas of the world. Merging these results with DEMs allows a predictive capability that could be useful in policy development and security planning.

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

2002-05-01

157

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

158

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

159

Monitoring Glacial Advance and Retreat of the Skaftafellsjkull Glacier, Iceland  

Microsoft Academic Search

Visual documentation of glaciers can provide daily, seasonal, and yearly statistics concerning their advance and retreat, as well as contribute to historical record. Recognizing how glaciers change will improve glacier models, which leads to a better understanding of climate and ice-sheet interactions. Obtaining frequent images of glaciers can be difficult since they are often located in remote locations with rugged

Bryce L. Carmichael; Amber E. Smith

160

Results from the new Swiss Glacier Inventory 2000  

Microsoft Academic Search

For the new Swiss Glacier Inventory 2000 Landsat TM images from 1985, 1992 and 1998\\/9 were processed in a GIS environment. Thresholded TM4 \\/ TM5 ratio images were used to classify clean glacier ice and the combination with a DEM provided 3D glacier parameters. The 1973 Swiss glacier inventory was digitized and used as the base data set as well

F. Paul; A. Kaeaeb; M. Maisch; T. Kellenberger; W. Haeberli

2003-01-01

161

Black soot and the survival of Tibetan glaciers  

PubMed Central

We find evidence that black soot aerosols deposited on Tibetan glaciers have been a significant contributing factor to observed rapid glacier retreat. Reduced black soot emissions, in addition to reduced greenhouse gases, may be required to avoid demise of Himalayan glaciers and retain the benefits of glaciers for seasonal fresh water supplies. PMID:19996173

Xu, Baiqing; Cao, Junji; Hansen, James; Yao, Tandong; Joswia, Daniel R.; Wang, Ninglian; Wu, Guangjian; Wang, Mo; Zhao, Huabiao; Yang, Wei; Liu, Xianqin; He, Jianqiao

2009-01-01

162

Glacier Change and an Updated Glacier Inventory of Mongolia using Landsat 8  

NASA Astrophysics Data System (ADS)

Mountain glaciers and ice caps around the world are recognized as significant contributors to both global sea level and local and regional water resources, especially for arid regions. However, the remote and rugged nature of glaciers in many parts of Asia hinders their study. To complicate the picture, not only are glaciers in High Mountain / Central / North Asia exhibiting considerable regional variability in mass balance, but different measurement methods are painting significantly different pictures of glacier health. Mongolia provides a subset of the global glacier inventory which exemplifies low data availability and seemingly contradictory results. Based on previous studies, Mongolia is home to ~500 glaciers totaling ~650 km2, but these figures are quite rough. Regional glacier mass balance estimates vary from -2 1 Gt / yr to 3 6 Gt / yr. However, the glaciers are important to the local environment and agriculture, as Mongolian glaciers are estimated to store 10% of Mongolia's fresh water. The glaciers have lost ~6% of their area from the 1960s to the 1990s. Most recent studies of high mountain Asia (the large group of glaciated ranges between the Tien Shan, Qilian Mountains, and the Himalayas) show accelerated losses in recent years. Therefore, from within this uncertainty, we harness newly available data from Landsat 8's Operational Land Imager (OLI) to build an updated glacier inventory for Mongolia. Prior regional studies have focused of a variety of sub-ranges across many different epochs within the Altai (i.e. Munkh Khairkhan, Tavan Bogd, Turgen, Kharkhiraa, Munkhkhairkhan, Sair, and Tsambagarav Mountains); here, we unify the picture of recent change for all of Mongolia's glaciers (i.e., the additional glaciated areas eastward of the Altai). In addition to highlighting the ease and utility of Landsat 8's OLI, we will take advantage of a further suite of data (i.e. Landsat archival imagery, ICESat, ASTER, SPOT-5, or submeter imagery) to further document glacier change in the Mongolian Altai.

Pope, A.; Scambos, T. A.

2013-12-01

163

Englacial hydrology of Annette Plateau, a temperate alpine glacier, Southern Alps, New Zealand.  

E-print Network

??The movement of water through temperate glaciers is important for understanding fundamental issues within glaciology. These include glacier induced floods, glacier dynamics and run-off prediction. (more)

Schaller, Kolja

2013-01-01

164

Climate Change and Glacier Retreat: Scientific Fact and Artistic Opportunity  

Microsoft Academic Search

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

D. B. Fagre

2008-01-01

165

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

166

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

167

Alaska PaleoGlacier Atlas: A Geospatial Compilation of Pleistocene Glacier Extents  

NSDL National Science Digital Library

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

William Manley

168

New evidence for an ENSO impact on low-latitude glaciers: Antizana 15, Andes of Ecuador, 028'S  

NASA Astrophysics Data System (ADS)

Continuous monthly mass balance measurements from the ablation zone of Antizana 15 glacier in the Andes of Ecuador between January 1995 and December 2002 indicate a strong dependence on El Nio-Southern Oscillation (ENSO). Over the 8-year period investigated, mass balance was negative all year round during El Nio periods but remained close to equilibrium (positive anomalies) during La Nia events. On seasonal timescales, mean ablation rates remain at a quite constant level all year round, but interannual variability shows much larger changes from year to year during the key periods February-May and September. This variability is caused by large differences that occur in the seasonal cycle during the two opposite phases of ENSO. Since ENSO is phase locked to the seasonal cycle with largest sea surface temperature anomalies around boreal winter, November-February, and the atmospheric response to ENSO is delayed by 3 months over the Ecuadorian Andes, year-to-year variations in mass balance are largest between February and May. Energy balance studies at the glacier surface indicate that high air temperature, which favors rain over snowfall, weak and sporadic snowfall, insufficient to maintain a high glacier albedo, low wind speeds, which limit the transfer of energy from melting to sublimation, and reduced cloud cover, which increases the incoming short-wave radiation, are the dominant factors related to El Nio, which tend to increase ablation. La Nia events on the other hand are characterized by colder temperatures, higher snowfall amounts, and to a lesser degree, more constant winds, factors which increase albedo and sublimation and therefore preclude melting at the glacier surface. The effects of ENSO variability are also important over the accumulation area, which represents up to 80% of the glacier surface during La Nia events (1999-2000) and 45-60% in El Nio years. Since the accumulation rates increase during these cold periods, the specific net balance and the dynamics of the entire glacier are strongly affected. Longer mass balance records than this 8-year period are needed for conclusive answers about the dependence of the Ecuadorian glaciers on ENSO variability, but initial results suggest that the response observed on Antizana glaciers is very similar to what has been observed previously during ENSO periods on Andean glaciers in the outer tropics. The seasonal dependence on ENSO and the physical mechanisms linking ENSO with mass balance variations on Antizana, however, are different from the response observed on Andean glaciers in the outer tropics.

Francou, Bernard; Vuille, Mathias; Favier, Vincent; CCeres, Bolivar

2004-09-01

169

Biogeochemistry of glacier and rock glacier outflow in the western United States  

NASA Astrophysics Data System (ADS)

Glaciers are melting at unprecedented rates worldwide, releasing bioavailable minerals and nutrients and altering downstream biogeochemistry. Though much research has focused on the recession of ice-glaciers in alpine environments, far less is known about the melt dynamics and biogeochemistry of rock glaciers. Rock glaciers, which are mixtures of ice and rocks that flow like a glacier, are far more abundant in mountainous regions of the western United States than ice glaciers. Little is known about their influence on downstream hydrology and water quality. We report here preliminary results of a west-wide survey of the influence of glaciers and rock glaciers on headwater properties. Measurements of specific conductance, nitrate (NO3-), ammonium (NH4+), dissolved silica, and dissolved organic matter were compared between glaciers, rock glaciers, and snow-fed reference streams from three basins in the Colorado Front Range. Samples were collected from ice, where possible, and downstream at 500m intervals from the first flowing water to tree line. UV and fluorescence data were analyzed using excitation emission matrices (EEMs) and PARAFAC modeling. High concentrations of NH4+ were only found in ice and the most upstream locations; NH4+ was below detection at all lower elevation sites, whereas NO3- concentrations were low in the headwaters and higher downstream. The fluorescence spectrum of DOC from both ice and the highest elevations had a strong autochthonous (microbial or algal) signal that was replaced by a more allochtonous, terrestrially-derived DOC as it approached tree line. Rock glacier stream chemistry was intermediate between glacier-fed streams and strictly snow fed drainages. DOC levels for ice glaciers ranged 2-3mg/L with increasing values downstream, while rock glaciers ranged from 1-2.5 mg/L with attenuation downstream. Snowfed only streams had DOC values at detection <0.5mg/L, with the exception at Lake Husted outflow, with an upland wetland, unlike the other snow-fed streams sampled. SUVA 254, an index of aromaticity of the dissolved organic matter, was lower in streams fed by rock glaciers than ice glaciers and snow fed streams. This is potentially indicative of microbial processing in streams fed by rock glaciers. Fluorescence index was highest for ice glaciers (1.44), lowest for snow-fed streams (1.33), and a medial value for rock glaciers (1.42). Freshness index, which indicates the proportion of recently produced dissolved organic matter, was highest for ice glacier streams, and lowest for rock glacier streams, and showed the most variability between sites with snow-fed streams. More research is planned, but rock glaciers appear more similar to ice glaciers than snow-fed streams in their influence on alpine stream chemistry on biology, suggesting a trajectory of change of the mountains as ice features waste away.

Fegel, T. S.; Baron, J.; Hall, E.; Boot, C. M.

2013-12-01

170

Hidden Lake in Glacier National Park, Montana  

USGS Multimedia Gallery

Hidden Lake in Glacier National Park, Montana, USA, a high mountain lake in an alpine setting. This lake is kept full of water mainly from precipitation runoff from the surrounding hills and, in the spring, from snowmelt....

171

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.

172

Distinct patterns of seasonal Greenland glacier velocity  

NASA Astrophysics Data System (ADS)

Greenland Ice Sheet mass loss due to ice dynamics requires a complete understanding of spatiotemporal velocity fluctuations and related control mechanisms. We present a 5 year record of seasonal velocity measurements for 55 marine-terminating glaciers distributed around the ice sheet margin, along with ice-front position and runoff data sets for each glacier. Among glaciers with substantial speed variations, we find three distinct seasonal velocity patterns. One pattern indicates relatively high glacier sensitivity to ice-front position. The other two patterns are more prevalent and appear to be meltwater controlled. These patterns reveal differences in which some subglacial systems likely transition seasonally from inefficient, distributed hydrologic networks to efficient, channelized drainage, while others do not. The difference may be determined by meltwater availability, which in some regions may be influenced by perennial firn aquifers. Our results highlight the need to understand subglacial meltwater availability on an ice sheet-wide scale to predict future dynamic changes.

Moon, Twila; Joughin, Ian; Smith, Ben; Broeke, Michiel R.; Berg, Willem Jan; Nol, Brice; Usher, Mika

2014-10-01

173

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

174

Fuzzy Cognitive Maps for Glacier Hazards Assessment: Application to Predicting the Potential for Glacier Lake Outbursts  

NASA Astrophysics Data System (ADS)

Glaciers and ice sheets are among the largest unstable parts of the solid Earth. Generally, glaciers are devoid of resources (other than water), are dangerous, are unstable and no infrastructure is normally built directly on their surfaces. Areas down valley from large alpine glaciers are also commonly unstable due to landslide potential of moraines, debris flows, snow avalanches, outburst floods from glacier lakes, and other dynamical alpine processes; yet there exists much development and human occupation of some disaster-prone areas. Satellite remote sensing can be extremely effective in providing cost-effective and time- critical information. Space-based imagery can be used to monitor glacier outlines and their lakes, including processes such as iceberg calving and debris accumulation, as well as changing thicknesses and flow speeds. Such images can also be used to make preliminary identifications of specific hazardous spots and allows preliminary assessment of possible modes of future disaster occurrence. Autonomous assessment of glacier conditions and their potential for hazards would present a major advance and permit systematized analysis of more data than humans can assess. This technical leap will require the design and implementation of Artificial Intelligence (AI) algorithms specifically designed to mimic glacier experts reasoning. Here, we introduce the theory of Fuzzy Cognitive Maps (FCM) as an AI tool for predicting and assessing natural hazards in alpine glacier environments. FCM techniques are employed to represent expert knowledge of glaciers physical processes. A cognitive model embedded in a fuzzy logic framework is constructed via the synergistic interaction between glaciologists and AI experts. To verify the effectiveness of the proposed AI methodology as applied to predicting hazards in glacier environments, we designed and implemented a FCM that addresses the challenging problem of autonomously assessing the Glacier Lake Outburst Flow Potential and Impound Water Upstream Flow Potential. The FCM is constructed using what is currently our understanding of how glacier lake outbursts occur, whereas the causal connection between concepts is defined to capture the expertise of glacier scientists. The proposed graph contains 27 nodes and a network of connections that represent the causal link between concepts. To test the developed FCM, we defined three scenarios representing glacier lake environmental conditions that either occurred or that are likely to occur in such highly dynamic environments. For each case, the FCM has been initialized using observables extracted from hypothesized remote sensing imagery. The map, which converges to a fixed point for all of the test scenarios within 15 iterations, shows reasoning consistent with that of glacier experts. The FCM-based cognitive approach has the potential to be the AI core of real-time operational hazards assessment and detection systems.

Furfaro, R.; Kargel, J. S.; Fink, W.; Bishop, M. P.

2010-12-01

175

Glacier, glacier lake and permafrost distribution in the Brahmaputra river basin  

NASA Astrophysics Data System (ADS)

Glacier distribution, glacier changes, glacier lakes and their changes, and mountain permafrost occurrence are investigated and compared to climate scenarios in order to assess the influence of melting glaciers and degrading permafrost on the long-term runoff of the Upper Brahmaputra River. In this contribution we derive glacier inventories for three test areas in the Upper Brahmaputra River Basin based on semi-automatic classification of Landsat data of 2000 and supplementary ASTER data. The resulting glacier outlines are intersected with the glacier outlines of the Chinese Glacier Inventory from about the 1970s-1980s and compared to selected Corona satellite data from the 1960s. In total, an area loss of about 18% was observed over the period investigated. We estimate the according ice volume loss to be on the order of 20%. Using the Chinese Glacier Inventory and our inventory results we upscale the above glacier change to the entire Upper Brahmaputra River Basin. Glacier lakes are mapped for the boundary region between Bhutan and Tibet using 1990 and 2000 Landsat imagery. Changes in lake area are compared to the observed glacier changes. The permafrost distribution in the study region is estimated using regionally adapted versions of two empirical models, both originally developed to estimate the permafrost distribution on a regional scale in the Swiss Alps. One model (PERMAKART) applies a topo-climatic key, based on the relation between altitude above sea level, aspect, and permafrost probability. The second model (PERMAMAP) is based on a linear spatial relation between the bottom temperature of the winter snow cover (BTS), the mean annual air temperature (MAAT) and the potential direct solar radiation. Adaptation of the models is done through the inclusion of ground based meteorological data and validated using distribution patterns of rock glaciers. The latter are mapped from high resolution satellite data such as CORONA and Quickbird imagery. Both, the observed glacier changes and the modelled permafrost distribution are compared to climate simulations in order to estimate the recent and near-future climate change impact on the glaciers and mountain permafrost in the Upper Brahmaputra River basin.

Kb, A.; Frauenfelder, R.; Hoelzle, M.; Sossna, I.; Avian, M.

2009-04-01

176

Regional Observations of Alaska Glacier Dynamics  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

177

Greenland's pronounced glacier retreat not irreversible  

NASA Astrophysics Data System (ADS)

In recent decades, the combined forces of climate warming and short-term variability have forced the massive glaciers that blanket Greenland into retreat, with some scientists worrying that deglaciation could become irreversible. The short history of detailed glacier observations, however, makes pinning the ice loss to either short-term dynamics or long-term change difficult. Research by Young et al. detailing the effects of two bouts of sudden and temporary cooling during an otherwise warm phase in Greenland's climate history could help answer that question by showing just how heavy a hand short-term variability can have in dictating glacier dynamics. Along the western edge of Greenland the massive Jakobshavn Isbr glacier reaches out to the coast, its outflow dropping icebergs into Baffin Bay during the summer months. Flanking the glacier's tongue are the Tasiussaq and Marrait morainespiles of rock marking the glacier's former extent. Researchers suspected the moraines were tied to two periods of abrupt cooling that hit Greenland 9300 and 8200 years ago, and that association was reinforced by the authors' radiocarbon and beryllium isotope analyses of the area surrounding the moraines. Beryllium-10 forms when cosmic radiation travels through the atmosphere and strikes the Earth's surface, with surface rock concentrations indicating how long it has been ice-free.

Schultz, Colin

2012-02-01

178

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

179

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

180

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

181

Four+ Years of Measurements from the Mendenhall Glacier Terminus  

NASA Astrophysics Data System (ADS)

We describe the instrumentation, power, communications, and lessons learned from ongoing four+ years of measurements at the terminus of Mendenhall Glacier. In this presentation we focus on the most successful microserver deployment. The microserver is a simple rugged computer with a radio modem that can survive and operate outdoors in harsh environments like Antarctica. The system is called a microserver because of the networking capabilities, particularly as it may act as anchor points for localized lightweight sensor networks. SEAMONSTER, the SouthEast Alaska MOnitoring Network for Science, Technology, Education and Research, is a demonstration sensor web effort. The microserver design for SEAMONSTER is intended to provide general capabilities that could be used in harsh environments specifically for cryospheric observations. At the Mendenhall terminus the observations included meteorologic data and repeat digital photography. Other SEAMONSTER stations included snow accumulation and density, precision GPS, seismic, water pressure, and other measurements. Power generation at the Mendenhall deployment is both solar and wind.

Heavner, M.; Fatland, D. R.

2012-12-01

182

RESPONSE OF GLACIERS AND GLACIER RUNOFF IN ICELAND TO CLIMATE CHANGE  

Microsoft Academic Search

Climate changes are likely to have a substantial effect on glaciers and runoff from glaciated areas in the Nordic countries in the future. Many glaciers and ice caps are project ed to essentially disappear over the next 100-200 years. As a part of the Nordic CWE and CE research projects, a dynamical ice flow model coupled with a degree-day mass

Tmas Jhannesson; Gufinna Aalgeirsdttir; Helgi Bjrnsson; Finnur Plsson; Oddur Sigursson

183

Glacier Change in the Western Himalayas: A Case Study of Suru Glacier, Northern India  

Microsoft Academic Search

Mountain glaciers are considered as primary indicators to monitor the impact of climate change on regional temperature and precipitation patterns. They are linked to the atmosphere through mass and energy exchange which determine accumulation and ablation throughout the year. Since the advent of satellite remote sensing and its data availability to researchers from 1972 onwards, mapping and monitoring of glaciers

Susanne Schmidt; Marcus Nsser; M. S. Nathawat; S. Ghosh; A. C. Pandey

2010-01-01

184

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

Microsoft Academic Search

The Global Land Ice Measurement from Space (GLIMS) project is a cooperative effort of over sixty institutions world-wide with the goal of inventorying a majority of the world's estimated 160000 glaciers. Each institution (called a Regional Center, or RC) oversees the analysis of satellite imagery for a particular region containing glacier ice. Data received by the GLIMS team at the

Bruce Raup; Adina Racoviteanu; Siri Jodha Singh Khalsa; Christopher Helm; Richard Armstrong; Yves Arnaud

2007-01-01

185

Climate sensitivity of Tibetan Plateau glaciers - past and future implications  

NASA Astrophysics Data System (ADS)

The Tibetan Plateau is one of the most extensively glaciated, non-Polar regions of the world, and its mountain glaciers are the primary source of melt water for several of the largest Asian rivers. During glacial cycles, Tibetan Plateau glaciers advanced and retreated multiple times, but remained restricted to the highest mountain areas as valley glaciers and ice caps. Because glacier extent is dominantly controlled by climate, the past extent of Tibetan glaciers provide information on regional climate. Here we present a study analyzing the past maximum extents of glaciers on the Tibetan Plateau with the output of a 3D glacier model, in an effort to quantify Tibetan Plateau climate. We have mapped present-day glaciers and glacial landforms deposited by formerly more extensive glaciers in eight mountain regions across the Tibetan Plateau, allowing us to define present-day and past maximum glacier outlines. Using a high-resolution (250 m) higher-order glacier model calibrated against present-day glacier extents, we have quantified the climate perturbations required to expand present-day glaciers to their past maximum extents. We find that a modest cooling of at most 6C for a few thousand years is enough to attain past maximum extents, even with 25-75% precipitation reduction. This evidence for limited cooling indicates that the temperature of the Tibetan Plateau remained relatively stable over Quaternary glacial cycles. Given the significant sensitivity to temperature change, the expectation is perhaps that a future warmer climate might result in intense glacier reduction. We have tested this hypothesis and modeled the future glacier development for the three mountain regions with the largest present-day glacier cover using a projected warming of 2.8 to 6.2C within 100 years (envelope limits from IPCC). These scenarios result in dramatic glacier reductions, including 24-100% ice volume loss after 100 years and 77-100% ice volume loss after 300 years.

Heyman, Jakob; Hubbard, Alun; Stroeven, Arjen P.; Harbor, Jonathan M.

2013-04-01

186

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

187

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

188

Global-scale modeling of glacier mass balances for water resources assessments: Glacier mass changes between 1948 and 2006  

NASA Astrophysics Data System (ADS)

Glaciers play an important role for freshwater resources, but in global-scale freshwater assessments, their impact on river flows has not yet been taken into account. As a first step, we developed a global glacier model that can be coupled to global land surface and hydrological models. With a spatial resolution of 0.5 by 0.5, the glacier model HYOGA computes glacier mass balance by a simple degree-day approach for 50 m sub-grid elevation bands, modeling all glaciers within a grid cell as one glacier. The model is tuned individually for each grid cell against observed glacier mass balance data. HYOGA is able to compute glacier mass balances reasonably well, even those of summer accumulation type glaciers. Still, model uncertainty is high, which is, among other reasons, due to the uncertainty of global data sets of temperature and precipitation which do not represent well the climatic situation at glacier sites. We developed a 59-yr (1948-2006) time series of global glacier mass balance and glacier area by driving HYOGA with daily near-surface atmospheric data. According to our computations, most glaciers have lost mass during the study period. Compared to estimates derived from a rather small number of observed glacier mass balances, HYOGA computes larger glacier mass losses in Asia, Europe, Canadian Arctic islands and Svalbard. In accordance with the estimates, average annual mass losses have increased strongly after 1990 as compared to the 30 yrs before. The sea level equivalent of the melt water from glaciers is 0.76 mm/yr water equivalent after 1990 as compared to only 0.34 mm/yr water equivalent before. We computed an acceleration of glacier mass losses after 1990 for all world regions except South America, where the number of gauge observations of precipitation is very small after 1980.

Hirabayashi, Yukiko; Dll, Petra; Kanae, Shinjiro

2010-09-01

189

Predicting the Effect of Mountain Glacier Recession on Water Resources: A Modeling Study on the Bow Glacier, Alberta  

NASA Astrophysics Data System (ADS)

Meltwater from alpine glaciers provides critical water supply for vulnerable populations in the western Andes, the Himalayas and the eastern Canadian Rockies. Glacier recession is of major concern in these climate-sensitive regions where we seek to predict changes in watershed hydrology in selected glacierized river basins. The overarching research question of this investigation asks: How have changes in headwater glaciers affected water supply reliability in those parts of the world where streamflow dynamics are most affected by glacier sources? Our approach uses a process-based model that incorporates snow, glaciers, soil, groundwater, vegetation, and topography. The model is a newly modified version of the spatially distributed hydrology model, DHSVM, in which we have added a dynamic glacier submodel. The glacier submodel is initialized with satellite remote sensing-derived maps of glacier extent and a digital elevation model. It assumes conservation of mass, solving the continuity equation for ice and assumes Glen's ice creep law, a sliding law, and the shallow ice approximation. The glacier model can also handle transport and melt-out of debris cover, ice rheology, and isostatic adjustment for long model runs. Using the Bow Glacier, Alberta as an example, this presentation will focus on recent advances in the integrated modeling of glacier and snowmelt runoff and state-of-the-art remote sensing of glacier extent from ASTER and Landsat.

Nolin, A. W.; Lettenmaier, D. P.; Clarke, G. K.; Naz, B. S.; Burns, P. J.

2011-12-01

190

Can shrubs help to reconstruct historical glacier retreats?  

NASA Astrophysics Data System (ADS)

In the 21st century, most of the worlds glaciers are expected to retreat due to further global warming. The range of this predicted retreat varies widely as a result of uncertainties in climate and glacier models. To calibrate and validate glacier models, past records of glacier mass balance are necessary, which often only span several decades. Long-term reconstructions of glacier mass balance could increase the precision of glacier models by providing the required calibration data. Here we show the possibility of applying shrub growth increments as an on-site proxy for glacier summer mass balance, exemplified by Salix shrubs in Finse, Norway. We further discuss the challenges which this method needs to meet and address the high potential of shrub growth increments for reconstructing glacier summer mass balance in remote areas.

Buras, Allan; Hallinger, Martin; Wilmking, Martin

2012-12-01

191

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

NASA Video Gallery

The Columbia Glacier in Alaska is one of many vanishing around the world. Glacier retreat is one of the most direct and understandable effects of climate change. The consequences of the decline in ...

192

Test of a simple glacier retreat parameterization for two Norwegian ice cap glaciers  

NASA Astrophysics Data System (ADS)

In Norway, the ice cap glacier retreat will be an important phenomena under climate change projections and will largely influence water resources.Three new versions of a glacier retreat algorithm based on the parameterization proposed by Huss et al. (2010) are implemented and tested on the Distributed Element Water Model of the Norwegian Water Resources and Energy Directorate. After selection of the best performing algorithm version, the glacier retreat parameters of the model are calibrated on observed discharge and mass balance data for two ice cap glaciers in Norway: Nigardsbreen (maritime glacier) and Midtdalsbreen (semi continental glacier). The calibration performance is acceptable: ice thickness is reproduced with a Root Mean Square Error of 20 respectively 15 m for the two case studies; glacier annual mass balance is overestimated for negative years; daily discharge is reproduced with a Nash Sutcliffe performance criterion between 0.80-0.86 for the period of 1961-1990: Climate change projections are performed for these 2 glaciers using downscaled Regional Climate Models (RCMs) from IPCC A1B emission scenario for greenhouse gases. According to our results, these glaciers are going to decrease dramatically: the ice volume could be reduced by 70 to 80 % in 2100, the annual discharge could increase by 30% till 2070-2080. The annual daily regime can also be assumed to change: the simulation results show that the maximum discharge during summer will decrease whereas winter discharge will increase after a longer recession period in autumn. The beginning of the melting period will not change substantially. The model sensitivity of the applied glacier retreat parameterization (Huss et al. 2010) is analyzed with two approaches: 1/ comparing the ice volume evolution for all Huss parameters sets obtained through calibration in this study to the ones proposed in literature; 2/ varying one parameter after the other keeping the three others fixed. The evolution of the ice volume largely varies in function of the glacier retreat parameters and the parameter sets proposed in Huss et al. 2010 seem not to be able to capture the behavior of ice cap glaciers . From this study, the Huss parameterization implemented produced satisfying results and can be apply to ice cap in nordic countries for glacier retreat parameters calibrated. A classification of the ice cap could be necessary in order to widely apply this model without calibration process.

Alesina, Samuel; Beldring, Stein; Melvold, Kjetil; Schaefli, Bettina

2014-05-01

193

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

NSDL National Science Digital Library

This video contains a mix of live action video, stills, and computer animations of the Glacier Bay National Park in Glacier Bay, Alaska. Satellite mapping and imagery are used to show changes in the Glacier Bay area over a period of several years. Specific image processing techniques are discussed in relation to determining the evolution of glacier terminus points and in obtaining elevation data and how it is used to create fly-by visualizations of the area.

Cindy Starr

1996-02-23

194

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

195

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

196

Measuring Greenland Glacier Dynamics with Remotely Sensed Data  

E-print Network

in 2000 [A] and 2004-5 [B]. [Howat et. al., 2005]. Helheim Glacier System GIS Workflow 1. Download 2. Mosaic 3. Project 4. Subset (or clip) ____________________________________________________________________________ 5. Repeat 1-4 for NIR 8...Measuring Greenland Glacier Dynamics with Remotely Sensed Data Steve Foga University of Kansas, Geography M.A. Student Photo by: Phil Pasquini The importance of studying glacier ice Study area Difference in ice velocity of Helheim Glacier...

Foga, Steve

2013-01-15

197

Dendrochronology and Late Holocene History of Bering Piedmont Glacier, Alaska  

Microsoft Academic Search

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

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

1999-01-01

198

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

199

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

200

Snow Cover Effects on Glacier Ice Surface Temperature Margherita Maggioni*{  

E-print Network

Snow Cover Effects on Glacier Ice Surface Temperature Margherita Maggioni*{ Michele Freppaz* Paolo.maggioni@unito.it Abstract Snowpack evolution and glacier ice surface temperatures were studied on the Indren glacier of an artificial increase in the snow density was evaluated. During the season rich in snow there was a prevalence

Williams, Mark W.

201

Contrasting responses of Central Asian rock glaciers to global warming  

PubMed Central

While the responses of Tien Shan glaciers and glaciers elsewhere to climatic changes are becoming increasingly well understood, this is less the case for permafrost in general and for rock glaciers in particular. We use a novel approach to describe the climate sensitivity of rock glaciers and to reconstruct periods of high and low rock glacier activity in the Tien Shan since 1895. Using more than 1500 growth anomalies from 280 trees growing on rock glacier bodies, repeat aerial photography from Soviet archives and high-resolution satellite imagery, we present here the world's longest record of rock glacier movements. We also demonstrate that the rock glaciers exhibit synchronous periods of activity at decadal timescales. Despite the complex energy-balance processes on rock glaciers, periods of enhanced activity coincide with warm summers, and the annual mass balance of Tuyuksu glacier fluctuates asynchronously with rock glacier activity. At multi-decadal timescales, however, the investigated rock glaciers exhibit site-specific trends reflecting different stages of inactivation, seemingly in response to the strong increase in air temperature since the 1970s. PMID:25657095

Sorg, Annina; Kb, Andreas; Roesch, Andrea; Bigler, Christof; Stoffel, Markus

2015-01-01

202

Mass balance of three Svalbard glaciers reconstructed back to 1948  

Microsoft Academic Search

A simple model using upper-air meteorological variables in the NCEP-NCAR Reanalysis database is used to model seasonal components of mass balance of three glaciers in Svalbard. The model was originally developed for glaciers in North America, and has been applied to glaciers in Norway, Sweden and Iceland. Over the period for which mass balance data are available for the three

L. A. Rasmussen; J. Kohler

2007-01-01

203

Glaciers and their contribution to sea level change  

Microsoft Academic Search

Increased melting of glaciers and ice caps, excluding Greenland and Antarctica, will probably represent the second largest contribution to global sea level rise by 2100. The temperature sensitivity of sea level rise depends upon the global distribution of glacier areas, the temperature sensitivity of glacier mass balance in each region, the expected change of climate in each region, and changes

Roger J. Braithwaite; Sarah C. B. Raper

2002-01-01

204

Contrasting responses of Central Asian rock glaciers to global warming.  

PubMed

While the responses of Tien Shan glaciers - and glaciers elsewhere - to climatic changes are becoming increasingly well understood, this is less the case for permafrost in general and for rock glaciers in particular. We use a novel approach to describe the climate sensitivity of rock glaciers and to reconstruct periods of high and low rock glacier activity in the Tien Shan since 1895. Using more than 1500 growth anomalies from 280 trees growing on rock glacier bodies, repeat aerial photography from Soviet archives and high-resolution satellite imagery, we present here the world's longest record of rock glacier movements. We also demonstrate that the rock glaciers exhibit synchronous periods of activity at decadal timescales. Despite the complex energy-balance processes on rock glaciers, periods of enhanced activity coincide with warm summers, and the annual mass balance of Tuyuksu glacier fluctuates asynchronously with rock glacier activity. At multi-decadal timescales, however, the investigated rock glaciers exhibit site-specific trends reflecting different stages of inactivation, seemingly in response to the strong increase in air temperature since the 1970s. PMID:25657095

Sorg, Annina; Kb, Andreas; Roesch, Andrea; Bigler, Christof; Stoffel, Markus

2015-01-01

205

Extracting a Climate Signal from 169 Glacier Records  

Microsoft Academic Search

I constructed a temperature history for different parts of the world from 169 glacier length records. Using a first-order theory of glacier dynamics, I related changes in glacier length to changes in temperature. The derived temperature histories are fully independent of proxy and instrumental data used in earlier reconstructions. Moderate global warming started in the middle of the 19th century.

J. Oerlemans

2005-01-01

206

Rapid disintegration of Alpine glaciers observed with satellite data  

Microsoft Academic Search

Analyses of multispectral satellite data indicate accelerated glacier decline around the globe since the 1980s. By using digitized glacier outlines inferred from the 1973 inventory and Landsat Thematic Mapper (TM) satellite data from 1985 to 1999, we obtained area changes of about 930 Alpine glaciers. The 18% area reduction as observed for the period 1985 to 1999 (-1.3% a-1) corresponds

Frank Paul; Andreas Kb; Max Maisch; Tobias Kellenberger; Wilfried Haeberli

2004-01-01

207

The physical basis of glacier volume-area scaling  

Microsoft Academic Search

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

David B. Bahr; Mark F. Meier; Scott D. Peckham

1997-01-01

208

Glacier melt contribution to streamflow1 Neil Schaner1  

E-print Network

1 Glacier melt contribution to streamflow1 Neil Schaner1 , Nathalie Voisin2 , Bart Nijssen1), the global contribution of glaciers to water supply is33 not well known (Armstrong, 2010). While some vulnerability. Armstrong (2010) summarizes the current state41 of understanding of glacier contributions

Washington at Seattle, University of

209

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.

210

Historic Glacier Change using a GIS: Progress and problems  

Microsoft Academic Search

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

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

2004-01-01

211

GLACIER MONITORING FROM ASTER IMAGERY: ACCURACY AND APPLICATIONS  

E-print Network

GLACIER MONITORING FROM ASTER IMAGERY: ACCURACY AND APPLICATIONS A. Kääb1 , C. Huggel1 , F. Paul1 and Reflection Radiometer) on board the Terra satellite offers new possibilities for worldwide glacier monitoring be expected. (b) Automatic glacier mapping using the ASTER bands 3 (15 m resolution) and 4 (30 m resolution

Oldenburg, Carl von Ossietzky Universität

212

Combined technologies allow rapid analysis of glacier changes  

Microsoft Academic Search

Monitoring of glacier changes plays an important role within the Global Climate Observing System (GCOS) [Haeberli et al., 2000] and Landsat imagery has proven to be a useful tool for monitoring glacier changes over large and remote areas [Aniya et al., 1996; Li et al., 1998]. An accurate glacier map can be obtained by simple segmentation of a ratio image

Frank Paul

2002-01-01

213

Rapid disintegration of Alpine glaciers observed with satellite data  

Microsoft Academic Search

Analyses of multispectral satellite data indicate accelerated glacier decline around the globe since the 1980s. By using digitized glacier outlines inferred from the 1973 inventory and Landsat Thematic Mapper (TM) satellite data from 1985 to 1999, we obtained area changes of about 930 Alpine glaciers. The 18% area reduction as observed for the period 1985 to 1999 (?1.3% a?1) corresponds

Frank Paul; Andreas Kb; Max Maisch; Tobias Kellenberger; Wilfried Haeberli

2004-01-01

214

Global-scale modeling of glacier mass balances for water resources assessments: Glacier mass changes between 1948 and 2006  

Microsoft Academic Search

Glaciers play an important role for freshwater resources, but in global-scale freshwater assessments, their impact on river flows has not yet been taken into account. As a first step, we developed a global glacier model that can be coupled to global land surface and hydrological models. With a spatial resolution of 0.5 by 0.5, the glacier model HYOGA computes glacier

Yukiko Hirabayashi; Petra Dll; Shinjiro Kanae

2010-01-01

215

Malaspina Glacier, Alaska, Anaglyph with Landsat Overlay  

NASA Technical Reports Server (NTRS)

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

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

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

The stereoscopic effect of this anaglyph was created by registering a Landsat image to the SRTM elevation model and then generating two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter.

Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data matches the 30-meter (98-foot) resolution of most Landsat images and substantially helps in analyzing the large and growing Landsat image archive.

Elevation data used in this image were acquired by the Shuttle Radar Topography Mission aboard the Space Shuttle Endeavour, launched on February 11, 2000. The mission used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar that flew twice on the Space Shuttle Endeavour in 1994. The Shuttle Radar Topography Mission was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between NASA, the National Imagery and Mapping Agency of the U.S. Department of Defense, and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC. Size: 55 x 55 kilometers (34 x 34 miles) Location: 60 deg N latitude, 140 deg W longitude Orientation: North at top Image Data: Landsat Thematic Mapper visible and infrared band mix Original Data Resolution: SRTM 1 arcsecond (30 mete

2003-01-01

216

An automatic method to create flow lines for determination of glacier length: A pilot study with Alaskan glaciers  

NASA Astrophysics Data System (ADS)

Glacier length is a key parameter in global glacier inventories, but difficult to determine in a consistent way and subject to frequent change. Its vector representation (a flow line) is a most important input for modeling future glacier evolution, but only seldom available from digital databases. Hence, there is an urgent need to generate such flow lines for a large number of glaciers from automated methods. We here present a new algorithm that is based on Python scripting and additional libraries (GDAL and OGR) and requires only a DEM and glacier outlines as an input. The core of the method is based on a glacier axis concept that is combined with geometry rules such as the k-d Tree, Nearest Neighbor and crossing test theory. We have applied the method to 400 glaciers located in Western Alaska, where a new glacier inventory was recently created. The accuracy of the method was assessed by a quantitative and qualitative (outline overlay) comparison with a manually digitized dataset for 20 glaciers. This comparison revealed for 17 out of the 20 glaciers a length value within the range of the manual digitizations. Other potential methods performed less well. Combined with previous glacier outlines from the same region (Digital Line Graph) we automatically determined length changes for 390 glaciers over a c. 50 year period.

Le Bris, Raymond; Paul, Frank

2013-03-01

217

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

218

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

219

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

220

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

221

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

222

Columbia Glacier in 1986; 800 meters retreat  

USGS Publications Warehouse

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

Krimmel, R.M.

1987-01-01

223

Rapid ice discharge from southeast Greenland glaciers  

E-print Network

Trans. AGU, 84(6), Fall Meet. Suppl., Abstract C32A-0418. Meier, M., and A. Post (1987), Fast tidewater glaciers, J. Geophys. Res., 92(B9), 90519058. Michel, R., and E. Rignot (1999), Flow of Moreno Glaciar, Argentina, from repeat-pass Shuttle Imaging..., ice sounding radar profiles were acquired by the NASA/University of Kansas radar [Gogineni et al., 2001] in east Greenland (Figure 1). In May 2003, new data were acquired across Helheim Glacier, at a higher elevation than in prior attempts which failed...

Rignot, E.; Braaten, David A.; Gogineni, S. Prasad; Krabill, W. B.; McConnell, J. R.

2004-03-25

224

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.

225

Sensitivity of glaciers and small ice caps to greenhouse warming  

SciTech Connect

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. This corresponds to a sea-level rise of 0.58 millimeter per year, a value significantly less than earlier estimates.

Oerlemans, J.; Fortuin, J.P.F. (Utrecht Univ. (Netherlands))

1992-10-02

226

Malaspina Glacier, Alaska as seen from STS-66 Atlantis  

NASA Technical Reports Server (NTRS)

Malaspina Glacier can be seen in this north-northeastern photograph taken in November, 1994. The glacier, located in the south shore of Alaska is a classic example of a piedmont glacier lying along the foot of a mountain range. The principal source of ice for the glacier is provided by the Seward Ice Field to the north (top portion of the view) which flows through three narrow outlets onto the coastal plain. The glacier moves in surges that rush earlier-formed moraines outward into the expanding concentric patterns along the flanks of the ice mass.

1994-01-01

227

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

228

Little Ice Age glaciers in Britain: Glacierclimate modelling in the Cairngorm Mountains  

SciTech Connect

It is widely believed that the last glaciers in the British Isles disappeared at the end of the Younger Dryas stadial (12.911.7 cal. kyr BP). Here, we use a glacierclimate model driven by data from local weather stations to show for the first time that glaciers developed during the Little Ice Age (LIA) in the Cairngorm Mountains. Our model is forced from contemporary conditions by a realistic difference in mean annual air temperature of -1.5 degrees C and an increase in annual precipitation of 10%, and confirmed by sensitivity analyses. These results are supported by the presence of small boulder moraines well within Younger Dryas ice limits, and by a dating programme on a moraine in one cirque. As a result, we argue that the last glaciers in the Cairngorm Mountains (and perhaps elsewhere in upland Britain) existed in the LIA within the last few hundred years, rather than during the Younger Dryas.

Stephan Harrison; Ann V. Rowan; Neil F. Glasser; Jasper Knight; Mitchell A. Plummer; Stephanie C. Mills

2014-02-01

229

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

E-print Network

for British Columbia. We are beginning to understand that our water supply. Rapidly receding glaciers are becoming an important water resource concern in the late twentieth century. Water is vital not only as a resource for human use

Smith, Dan

230

Origin, Evolution, and Preservation of Cold Based Debris Covered Glaciers: Quantifying Sublimation Rates of Ancient Buried Ice in Antarctica  

NASA Astrophysics Data System (ADS)

Growing interest in our planet's climate history has placed a premium on acquiring detailed records of past climate change. Of considerable interest are archives of ancient atmosphere trapped within the debris-covered alpine glaciers of the western Dry Valleys region of Antarctica. The Mullins Valley debris-covered glacier (~8 km in length) is sourced from local snowfall at the steep headwall of the valley. The first 1.2 km of this glacier is generally free of overlying debris except for isolated cobbles and boulders. Thereafter, the ice surface is covered with a thin, continuous sheet of dolerite-rich rubble. Factors that influence the origin and modification of this ice include atmospheric temperature and relative humidity, precipitation, incoming solar radiance, surface albedo, till texture, winds, surface roughness, salts, and secondary ice lenses. We applied a diffusion model to track vapor flux within a sublimation till overlying the Mullins Valley debris-covered glacier, purportedly the world's oldest debris-covered alpine glacier. As input, we used meteorological data from HOBO data loggers that captured climate change and till temperatures. Results show that vapor flows into and out of the sublimation till at rates dependent on the non-linear variation of soil temperature with depth. Sublimation rates along the Mullins Glacier varied as a function of till thickness, local climate (using a calculated regional lapse rate of 0.88C per 100 m), and till texture. Ice loss during the study interval (November 27, 2006 to December 24, 2006) ranged from as high as 2.12 mm for exposed glacier ice in the upper ablation zone, to as low as 0.01 mm for buried ice beneath till >50 cm in thickness. Averaged over the entire ablation zone (6.7 km2), this yields a net ice-surface lowering of 0.32 mm during the study interval. Numerical modeling suggests that a modest ice accumulation rate at the headwall of ~1 cm a-1 appears sufficient to maintain current ice volumes. Overall, our model results are consistent with an inferred Miocene age for distal portions of the Mullins Valley debris-covered glacier and suggests that ancient atmosphere may be preserved in buried glaciers in the western Dry Valleys region.

Kowalewski, D. E.; Marchant, D. R.

2007-12-01

231

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

232

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

233

Glacier dynamics at Helheim and Kangerdlugssuaq glaciers, southeast Greenland, since the Little Ice Age  

NASA Astrophysics Data System (ADS)

Observations over the past decade show significant ice loss associated with the speed-up of glaciers in southeast Greenland from 2003, followed by a deceleration from 2006. These short-term, episodic, dynamic perturbations have a major impact on the mass balance on the decadal scale. To improve the projection of future sea level rise, a long-term data record that reveals the mass balance beyond such episodic events is required. Here, we extend the observational record of marginal thinning of Helheim and Kangerdlugssuaq glaciers from 10 to more than 80 years. We show that, although the frontal portion of Helheim Glacier thinned by more than 100 m between 2003 and 2006, it thickened by more than 50 m during the previous two decades. In contrast, Kangerdlugssuaq Glacier underwent minor thinning of 40-50 m from 1981 to 1998 and major thinning of more than 100 m after 2003. Extending the record back to the end of the Little Ice Age (prior to 1930) shows no thinning of Helheim Glacier from its maximum extent during the Little Ice Age to 1981, while Kangerdlugssuaq Glacier underwent substantial thinning of 230 to 265 m. Comparison of sub-surface water temperature anomalies and variations in air temperature to records of thickness and velocity change suggest that both glaciers are highly sensitive to short-term atmospheric and ocean forcing, and respond very quickly to small fluctuations. On century timescales, however, multiple external parameters (e.g. outlet glacier shape) may dominate the mass change. These findings suggest that special care must be taken in the projection of future dynamic ice loss.

Khan, S. A.; Kjeldsen, K. K.; Kjr, K. H.; Bevan, S.; Luckman, A.; Aschwanden, A.; Bjrk, A. A.; Korsgaard, N. J.; Box, J. E.; van den Broeke, M.; van Dam, T. M.; Fitzner, A.

2014-08-01

234

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

Microsoft Academic Search

A glaciological program has been undertaken since 1991 on Zongo glacier in Bolivia (60004850m asl, 2.4km2, 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

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

2007-01-01

235

Glacier melting in a stratified ocean: Observations from outlet glaciers in Greenland (Invited)  

NASA Astrophysics Data System (ADS)

Submarine melting is an important balance term for tidewater outlet glaciers in Greenland, and has emerged as a potential trigger for their recent acceleration, necessitating its inclusion in future prognostic ice-sheet models. Yet, our present understanding of the process is limited, largely because of a lack of measurements. Most existing studies pertain to tidewater glaciers terminating in fjords with shallows sills that allow the inflow of a single oceanic water mass. Greenlands fjords, on the other hand, are characterized by deep sills and a vigorous fjord/shelf exchange which allows both cold, fresh Arctic waters and warm, salty Atlantic waters, present on the shelf, to come in contact with the ice. As a result, submarine melting of outlet glaciers in Greenland occurs in strongly stratified waters. Here, we present oceanographic measurements from three major East Greenland glaciers, including winter measurements, which show that this stratification and, in particular, the density contrast between the Arctic and Atlantic waters, give rise to multiple overturning melt cells (as opposed to a single estuarine cell) at the ice-edge. The resulting heat transport and melt rate vary strongly with depth suggesting that the ocean waters around Greenland exert a strong control on the vertical profile of the glaciers terminus.

Straneo, F.; Sutherland, D. A.; Hamilton, G. S.; Cenedese, C.; Stearns, L. A.

2010-12-01

236

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

237

Glacier Change Investigation for Early Elementary Students  

NASA Astrophysics Data System (ADS)

Few opportunities exist for early elementary students to do inquiry or guided inquiry into topics dealing with climate change and glaciers. "Flubber" offers a simulation for the movement of glacial ice. It is inexpensive to make, stores well, and can be re-used. Students of all ages enjoy watching, measuring, and thinking about flubber and what it represents. As the interest in ice sheets continues to build, activities that both help to illustrate how glaciers move and provide a launch pad for student-driven investigations need to be available to teachers. With support from the National Science Foundation's Science and Technology Center for the Remote Sensing of Ice Sheets (CReSIS), a set of activities has been developed to provide opportunities for early elementary students to develop inquiry skills within the standards for early elementary grades bands in the National Science Education Standards. Lesson plans, instructions for making and using "Flubber", student worksheets, teacher guides with glacier and climate change information, and a chart of the National Science Education Standards applicable to the activities are available to elementary teachers wishing to introduce their students to glaciers and climate change.

Hintz, R. S.; Landis, C.

2008-12-01

238

Uncertainty in Glacier Mass Balance Measurements  

Microsoft Academic Search

Direct, field-based methods of assessing the mass balance of alpine glaciers are based on a set of straightforward measurements of density and surface height change. Measurement uncertainties are generally small relative to the magnitude of the measurement. However, the uncertainties become substantial because the measurements offset each other due to zones of snow accumulation and zones of ice and snow

A. G. Fountain

2005-01-01

239

Controls On The Incidence of Glacier Surging  

Microsoft Academic Search

Glacier surging is an internally triggered cyclic flow instability with fast flow during the active phase believed to result from extreme subglacial water pressure. Whether the surge is promoted and sustained by sliding at the ice-bed interface or deforma- tion of weakened subglacial material is unknown, hence the surge mechanism and associated controls remain elusive. Through the generation and adaptation

K. Hayes

2002-01-01

240

Glacier Surge After Ice Shelf Collapse  

Microsoft Academic Search

The possibility that the West Antarctic Ice Sheet will collapse as a consequence of ice shelf disintegration has been debated for many years. This matter is of concern because such an event would imply a sudden increase in sea level. Evidence is presented here showing drastic dynamic perturbations on former tributary glaciers that fed sections of the Larsen Ice Shelf

Hernn De Angelis; Pedro Skvarca

2003-01-01

241

The Bay in Place of a Glacier.  

ERIC Educational Resources Information Center

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

Howell, Wayne

1997-01-01

242

Geology Fieldnotes: Glacier National Park, Montana  

NSDL National Science Digital Library

Glaciers have played an important role in shaping this park, which is part of the Rocky Mountain chain and shares a border with Canada's Waterton Lakes National Park. Information on this site includes park geology, visitor information, photographs, and links to other resources.

243

4, 173211, 2008 Climate and glacier  

E-print Network

~no-Southern Oscillation (ENSO) is an important element of earth's ocean-climate system. To further understand its pastCPD 4, 173­211, 2008 Climate and glacier response to ENSO in subtropical Andes E. Dietze et al.0 License. Climate of the Past Discussions Climate of the Past Discussions is the access reviewed discussion

Boyer, Edmond

244

Asulkan Valley Avalanche Track, Glacier National Park  

E-print Network

Asulkan Valley Avalanche Track, Glacier National Park Penelope Simpson, Jessica Paramio Maciej with the use of these trails ranges from bear encounters to triggering an avalanche. As in many mountainous regions, a high avalanche risk exists in the park during the winter due to the steep, rugged terrain

Smith, Dan

245

The History of the Glacier Facies Concept  

Microsoft Academic Search

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

C. S. Benson

2001-01-01

246

Edge function analysis of glacier mechanics problems  

Microsoft Academic Search

The edge function method is considered for the analysis of plane strain problems in glacier mechanics. The essence of the approach is the approximation of the solution by a linear combination of analytical solutions (based on the complex variable formulation of anisotropic elasticity) of the field equations. The unknowns in the linear combination are obtained from a system of equations

W. Tad Pfeffer

1997-01-01

247

Calibration of hydrological models in glacierized catchments  

NASA Astrophysics Data System (ADS)

Glacierized catchments are important source regions for water, and detailed knowledge of water availability is a prerequisite for good resource management strategies. Reliable and physically consistent runoff simulations become even more important if climate change impacts on alpine water resources are to be assessed. However, hydrological modeling of glacierized catchments is challenging ice melt which represents an additional source of water. Thus, adequate calibration strategies are needed especially in data scarce regions. An important question is how powerful a limited amount of data might be for model calibration. Accordingly, we analyzed the calibration power of limited discharge measurements, mass balance observations and the combination of by means of both Monte Carlo analyzes and multi-criteria model performance evaluation. Ensembles of 100 parameter sets were selected by evaluating the simulations based on a limited and discrete number of discharge measurements, glacier mass balance, and the combination of discharge and mass balance observations. Using these ensembles then the runoff was simulated and evaluated for the entire runoff series. The results for the Vernagtferner catchment and the Venter Ache catchment in Austria indicated that a single annual glacier mass balance observation contained useful information to constrain hydrological models. Combining mass balance observations with a few discharge data improved the internal consistency and significantly reduced the uncertainties compared to parameter set selections based on discharge measurements alone. Information on discharge was required for at least 3 days during the melting season to obtain good ensemble predictions.

Konz, Markus; Seibert, Jan; Braun, Ludwig; Burlando, Paolo

2010-05-01

248

A Facies Model for Temperate Continental Glaciers.  

ERIC Educational Resources Information Center

Discusses the presence and dynamics of continental glaciers in the domination of the physical processes of erosion and deposition in the mid-latitudes during the Pleistocene period. Describes the use of a sedimentary facies model as a guide to recognizing ancient temperate continental glacial deposits. (TW)

Ashley, Gail Mowry

1987-01-01

249

Spatial patterns of Holocene glacier advance and retreat in Central Asia  

Microsoft Academic Search

Glaciers in the southern Himalayas advanced in the early Holocene despite an increase in incoming summer solar insolation at the top of the atmosphere. These glacier advances are in contrast to the smaller alpine glaciers in the western and northern regions of Central Asia. Two different glacier mass-balance models are used to reconcile this Holocene glacier history with climate by

Summer Rupper; Gerard Roe; Alan Gillespie

2009-01-01

250

COMPARISON OF TM-DERIVED GLACIER AREAS WITH HIGHER RESOLUTION DATA SETS  

E-print Network

classification of glaciers and GIS-based extraction of glaciers and their 3D parameters from a DEM have been by investigating the methods required for automated glacier mapping from TM data in a GIS environment (7, 8 glaciers are shown after GIS-based intersection with glacier basins. Within the SGI 2000, TM

Oldenburg, Carl von Ossietzky Universität

251

52 glaciers and one lake: how to reconstruct past regional glacier variability  

NASA Astrophysics Data System (ADS)

Sediment records from distal glacier-fed lakes have been used in numerous reconstructions of past glacier activity, where the basic assumption is that the amount of minerogenic material deposited in the lake is directly proportional to the amount of upstream glacier erosion. However, the minerogenic component of the sediments in a distal glacier-fed lake is commonly derived from several different sources, not only subglacial erosion. Furthermore, glacier reconstructions tend to focus on individual mountain glaciers, which due to local effects might not always reflect regional scale glacier variability. Presently, certain high-resolution analysis techniques allow for fast multi-proxy analyses of sediment cores, which improve the basis for inferring the provenance of lake sediments; however, the only way of actually testing such inferences is to identify the different sediment sources in the adjacent catchment and characterize them using the same proxy measurements as in the lake core. Multi-proxy sedimentary fingerprinting techniques are labor-intensive, however, and proxies such as bulk geochemistry may prove of little use in differentiating between source areas if the bedrock lithology is uniform across the catchment. Here we present a simple method based on environmental magnetism that allow for tracking lake sediments to their sources in catchments where the bedrock lithology is uniform. Unlike ferro- and ferrimagnetic minerals, the magnetic susceptibility of paramagnetic minerals is inversely proportional to temperature. Thus, by measuring the bulk magnetic susceptibility (chi-Bulk) of a sediment sample both at room temperature (293K) and after freezing in liquid nitrogen (77K), the relative contribution from paramagnetic minerals to the total chi-Bulk can be inferred from the ratio of chi-Bulk77K over chi-Bulk293K. Theoretically, a ratio of 3.8 will indicate a purely paramagnetic sample, whereas progressively lower values reflect an increasing contribution from ferro- or ferrimagnetic minerals. We found that in the catchment of Nerfloen, a distal lake draining a large (440 km2) catchment in western Norway that contains 52 separate glaciers, there was a systematic decrease in the chi-Bulk77K/chi-Bulk293K-ratio with increasing altitude and proximity to the glaciers. We have not studied the magnetic mineralogy of our samples in detail, but infer from our data that the relative amount of paramagnetic minerals increase as soil formation progresses, thereby creating the contrasting ratios between samples collected at different altitudes. In the lake core we observe rapid shifts between sedimentary regimes dominated by high- and low-altitude source areas, which can best be explained by regional-scale growth and decay of mountain glaciers in the lake catchment.

Vasskog, Kristian; Paasche, yvind; Nesje, Atle; Boyle, John F.; Birks, H. John B.

2014-05-01

252

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

253

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

254

Glacier volume changes at Mt. Everest/Qomolangma 1962 - 2007  

NASA Astrophysics Data System (ADS)

The larger glaciers at Mt. Everest are heavily covered with supra-glacial debris like many other glaciers in the Himalaya. Most glacier change studies concentrate on area change only. However, the melting of debris-covered glaciers is most recognisable through downwasting. Hence, multi-temporal DEM analysis is needed to study the reaction of these glaciers to climate change in detail. We generated a time series of DEMs based on stereo corona (years 1962 and 1972) aerial images (1984), ASTER (2001) and Cartosat-1 data (2007) for the southern side of Mt. Everest (investigated glaciers: Khumbu, Nuptse, Lhotse, Lhotse Nup, Lhotse Shar and Imja) and two DEMs for the northern side (Rongbuk Glacier) based on a topographic map (1974) and ASTER data (2003). IceSat GLAS data, topographic maps and field GPS measurements are used for validation. The Cartosat-1 DEM was chosen to be the master DEM due to the highest accuracy and the other DEMs were co-registered to it. The characteristics of the downwasting are similar for all investigated glaciers: The downwasting is pronounced in the upper part with thin debris-cover and less pronounced but still recognisable in the lower parts with thick debris-cover. The highest surface lowering at the southern side is found at the possible transition zone between the active and stagnant glacier parts. The average downwasting for the investigated Eastern Rongbuk Glacier seems to be little higher (0.81 0.53 m/a) than the value for Khumbu Glacier (0.42 0.21 m/a). Both the accumulation and ablation area of Khumbu Glacier showed a surface lowering. Volume loss is detected for all glaciers and investigated time periods.

Bolch, Tobias; Piezconka, Tino; Chen, Feng; Kang, Shichang; Buchroithner, Manfred

2010-05-01

255

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

256

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

257

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

258

A study of discrete glacier motion  

NASA Astrophysics Data System (ADS)

Knowledge of process which control glacial dynamics are imperative in quantifying the response of a glacier or ice sheet to external forcing. This dissertation focuses mainly upon the characterization of sliding ice over a bed in an unstable fashion. I investigate unstable sliding through instances where it is observed in passive seismology as well as a focused laboratory study. The laboratory study attempts to isolate specific aspects of the sliding interface, which could lead to unstable sliding. Implications of unstable sliding with regards to erosion are also dealt with. Initially the TAMSEIS array is used to observe a unique set of seismicity originating at the base of David Glacier Antarctica in which 20,000 events were located over a 300 day period as the ice slid over an asperity. Tidal effects at the terminus modulated the interevent spacing and magnitude of events allowing for a basic analysis of healing process between a glacier and its bed. The 300 day period of repeat seismicity is hypothesized to arise from advection of debris rich ice over the asperity. Next the erosion implications of stick slip sliding are investigated. Sudden advancement associated with seismic energy generation is hypothesized to rapidly expand water filled cavities, which form in lee of bedrock highs. The rapid expansion creates a drop in water pressure within the cavity resulting in a pressure gradient leading to rapid fracture of bedrock. During the interseismic period of a stick slipping glacier the static coefficient of friction transfers a larger shear stress to the bed than the dynamic coefficient of friction from stably sliding glacier would. Next laboratory experimentation is conducted using a biaxial shearing apparatus in order to test the hypothesis that debris rich ice can affect the stability regime of a sliding glacier. This is preformed on a suite of ice-debris samples with range entrained debris percentages and temperatures. Both synthetic ice constructed in the laboratory and natural ice taken from the base of Engabreen Glacier were tested. Transition from a velocity strengthening to velocity weakening interface was observed for a constant velocity if the debris amount was increased thus validating the initial hypothesis. These exterminations were followed by a set of experiments in which the biax was de-stiffened in order to replicate the elastic strain, which would be accumulated at the base of a glacier. When driven under conditions previously identified in the unstable slip regime unstable sliding did occur. This allowed for exploration unstable slip parameters. Specifically comparisons of stress drop with recurrence interval, and peak-sliding velocity was investigated. Next POLENET seismic data was used to investigate a set of repeating ruptures occurring near the Executive Committee Range of Marie Byrd Land Antarctica, a known source of volcanic activity. Surface velocities as low as V ? 30 m yr--1 in this region exist indicating the source of glacially generated seismicity was atypical. A proposed source of a sudden addition of basal melt water from an increase in geothermal heat flux is hypothesized to result in the seismic signature observed. Lastly the POLENET dataset was used to investigate calving events located at the terminus of Thwaites Glacier. The seismicity displayed a monochromatic signal. A new calving mechanism, which could produce such a source of seismicity, is theorized as resonating within the block, which is being calved off.

Zoet, Lucas K.

259

Microbial Energetics Beneath the Taylor Glacier, Antarctica  

NASA Astrophysics Data System (ADS)

Subglacial microbiology is controlled by glacier hydrology, bedrock lithology, and the preglacial ecosystem. These factors can all affect metabolic function by influencing electron acceptor and donor availability in the subglacial setting leaving biogeochemical signatures that can be used to determine ecosystem processes. Blood Falls, an iron-rich, episodic subglacial outflow from the Taylor Glacier in the McMurdo Dry Valleys Antarctica provides an example of how microbial community structure and function can provide insight into subglacial hydrology. This subglacial outflow contains cryoconcentrated, Pliocene-age seawater salts that pooled in the upper Taylor Valley and was subsequently covered by the advance of the Taylor Glacier. Biogeochemical measurements, culture-based techniques, and genomic analysis were used to characterize microbes and chemistry associated with the subglacial outflow. The isotopic composition of important geochemical substrates (i.e., ?34Ssulfate, ?33Ssulfate, ?18Osulfate, ?18Owater, ?14SDIC) were also measured to provide more detail on subglacial microbial energetics. Typically, subglacial systems, when driven to anoxia by the hydrolysis of organic matter, will follow a continuum of redox chemistries utilizing electron acceptors with decreasing reduction potential (e.g., Fe (III), sulfate, CO2). Our data provide no evidence for sulfate reduction below the Taylor Glacier despite high dissolved organic carbon (450 ?M C) and measurable metabolic activity. We contend that, in the case of the Taylor Glacier, the in situ bioenergetic reduction potential has been 'short-circuited' at Fe(III)-reduction and excludes sulfate reduction and methanogenesis. Given the length of time that this marine system has been isolated from phototrophic production (~2 Mya) the ability to degrade and consume increasingly recalcitrant organic carbon is likely an important component to the observed redox chemistry. Our work indicates that glacier hydrology imparts strong feedbacks on the availability of oxygen as an electron acceptor and may be a robust regulator of the in situ metabolism. This biogeochemical regulation in turn affects the chemical nature of subglacial efflux. Blood Falls demonstrates that measurements of geochemistry and microbial diversity can support models of subglacial hydrology.

Mikucki, J. A.; Turchyn, A. V.; Farquhar, J.; Priscu, J. C.; Schrag, D. P.; Pearson, A.

2007-12-01

260

Controlling mechanisms of Thwaites Glacier, West Antarctica  

NASA Astrophysics Data System (ADS)

Ice shelves play a major role in the stability of fast flowing ice streams in Antarctica, by exerting buttressing on inland ice and controlling the discharge of ice into the ocean. However, the mechanisms at work remain poorly understood and interactions between floating and grounded ice need to be better characterized in order to estimate the impact of climate change on the ice sheets. Thwaites glacier, in West Antarctica, features a small and heavily fractured ice shelf that provides limited back stress pressure on inland ice but is pinned on the eastern part on a prominent ridge. Thwaites glacier has maintained a consistently high velocity and negative mass balance for at least 20 years. Recent observations show a widening of its fast flowing area as well as a sustained acceleration since 2006 and a rapid retreat of its grounding line in the center of the glacier. The objective of this work is to characterize the dynamic response of Thwaites glacier to changes in its floating tongue on decadal to centennial time scales. To achieve this objective, we rely on high resolution ice flow modeling and grounding line dynamics using the Ice Sheet System Model (ISSM). We will focus on the complex interplay between the main floating tongue of Thwaites Glacier and its eastern, slow moving ice shelf, which is pinned down by an ice rumple. The speed of the eastern ice shelf is strongly affected by the coupling with the main floating ice tongue, which results in significant fluctuations in speed of the eastern ice shelf the formation of ice shelf cracks at the grounding line during acceleration phases. Our results show that ice rigidity at the junction between the eastern and western part of the shelf controls the dynamic regime of the ice shelf and suggest that Thwaites Glacier is likely to undergo substantial changes in the coming decades. This work was performed at the California Institute of Technology's Jet Propulsion Laboratory and the University of California Irvine under a contract with the National Aeronautics and Space Administration, Cryospheric Sciences and Modeling, Analysis and Prediction Programs

Seroussi, H. L.; Morlighem, M.; Rignot, E. J.; Larour, E. Y.; Mouginot, J.; Khazendar, A.

2013-12-01

261

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.

262

Satellite Observations of Glacier Surface Velocities in Southeast Alaska  

NASA Astrophysics Data System (ADS)

Glaciers in southeast Alaska are undergoing rapid changes and are significant contributors to sea level rise. A key to understanding the ice dynamics is knowledge of the surface velocities, which can be used with ice thickness measurements to derive mass flux rates. For many glaciers in Alaska, surface velocity estimates either do not exist or are based on data that are at least a decade old. Here we present updated maps of glacier surface velocities in southeast Alaska produced through a pixel tracking technique using synthetic aperture radar data and high-resolution optical imagery. For glaciers with previous velocity estimates, we will compare the results and discuss possible implications for ice dynamics. We focus on Glacier Bay and the Stikine Icefield, which contain a number of fast-flowing tidewater glaciers including LeConte, Johns Hopkins, and La Perouse. For the Johns Hopkins, we will also examine the influence a massive landslide in June 2012 had on flow dynamics. Our velocity maps show that within Glacier Bay, the highest surface velocities occur on the tidewater glaciers. La Perouse, the only Glacier Bay glacier to calve directly into the Pacific Ocean, has maximum velocities of 3.5 - 4 m/day. Johns Hopkins Glacier shows 4 m/day velocities at both its terminus and in its upper reaches, with lower velocities of ~1-3 m/day in between those two regions. Further north, the Margerie Glacier has a maximum velocity of ~ 4.5 m/day in its upper reaches and a velocity of ~ 2 m/day at its terminus. Along the Grand Pacific terminus, the western terminus fed by the Ferris Glacier displays velocities of about 1 m/day while the eastern terminus has lower velocities of < 0.5 m/day. The lake terminating glaciers along the Pacific coast have overall lower surface velocities, but they display complex flow patterns. The Alsek Glacier displays maximum velocities of 2.5 m/day above where it divides into two branches. Velocities at the terminus of the northern branch reach 1 m/day while the terminus of the southern branch moves about 2 m/day. Grand Plateau Glacier also divides into two main branches, with a northern branch displaying peak velocities of 1.5 m/day and a southern branch flowing at a rate of 1 m/day. The Stikine Icefield contains a number of large tidewater glaciers showing maximum velocities near their termini. At the terminus of the South Sawyer Glacier, velocities reach a peak of about 2 m/day. Along the terminus of the Dawes Glacier, velocities reach 3.5 m/day. The Baird Glacier displays lower velocities of 1-1.5 m/day. LeConte Glacier has 2-3 m/day velocities in its upper regions with higher velocities near its terminus. In contrast to the pattern shown by the surrounding glaciers, the Great Glacier has a peak velocity of 2 m/day in the upper portion of the glacier and a velocity of only 0.5 m/day near its terminus.

Elliott, J.; Melkonian, A. K.; Pritchard, M. E.

2012-12-01

263

Mass loss on Himalayan glacier endangers water resources  

NASA Astrophysics Data System (ADS)

Ice cores drilled from glaciers around the world generally contain horizons with elevated levels of beta radioactivity including 36Cl and 3H associated with atmospheric thermonuclear bomb testing in the 1950s and 1960s. Ice cores collected in 2006 from Naimona'nyi Glacier in the Himalaya (Tibet) lack these distinctive marker horizons suggesting no net accumulation of mass (ice) since at least 1950. Naimona'nyi is the highest glacier (6050 masl) documented to be losing mass annually suggesting the possibility of similar mass loss on other high-elevation glaciers in low and mid-latitudes under a warmer Earth scenario. If climatic conditions dominating the mass balance of Naimona'nyi extend to other glaciers in the region, the implications for water resources could be serious as these glaciers feed the headwaters of the Indus, Ganges, and Brahmaputra Rivers that sustain one of the world's most populous regions.

Kehrwald, Natalie M.; Thompson, Lonnie G.; Tandong, Yao; Mosley-Thompson, Ellen; Schotterer, Ulrich; Alfimov, Vasily; Beer, Jrg; Eikenberg, Jost; Davis, Mary E.

2008-11-01

264

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

265

IGARSS, 2002 JuneIGARSS, 2002 June Satellite Remote Sensing of Glaciers and IceSatellite Remote Sensing of Glaciers and Ice--dammeddammed  

E-print Network

's glaciers.(3) Complete GIS digital database of the world's glaciers. Principal observing instruments: ASTERIGARSS, 2002 JuneIGARSS, 2002 June Satellite Remote Sensing of Glaciers and IceSatellite Remote Sensing of Glaciers and Ice--dammeddammed Lakes: Pragmatic Issues and Case StudiesLakes: Pragmatic Issues

266

Characteristics of the turbulent flow in the surface layer of a Tropical Glacier  

NASA Astrophysics Data System (ADS)

Energy balance studies on glaciers mostly use aerodynamic profile methods, assuming hypotheses of Monin-Obukhov similarity theory are valid, in order to compute sensible and latent turbulent heat fluxes. Nevertheless, various turbulence measurements have shown that the turbulent flow in the surface layer is not in equilibrium and stationnary within mountainous rough topography. Few of these studies focus on tropical glaciers, and little is known about the dynamics of the surface layer in these environnments. We thus have deployed an extensive micro-meteorological experiment within the atmospheric surface layer over the ablation zone of the tropical Zongo glacier, Bolivia, during the dry season from July to August, 2007. Stations were installed around 5050 m a.s.l. They included two complete eddy covariance systems at a 2-m mean level and a 6-m mast measuring the mean profiles of air temperature and of wind speed. Data is used to characterize the conditions in the surface layer. Weakly stable conditions prevailed in the first meters above the ice or snow surface. With weak large scale forcing, a katabatic downslope flow with a wind maximum at about 2-m height usually appeared in the middle of the afternoon and maintained itself during most of the night. Profile data is fitted to derive roughness lenghts and characterize their evolution. The study of statistical moments of high frequency wind speed and temperature data shows that the wind regime was highly gusty and irregular. Stationary conditions were rarely encountered. Characteristics and structure of the turbulent flow were studied using spectral analysis. It shows that the observed turbulence cannot be generated only by local shear and that low frequency perturbations interact with the surface layer turbulence and lead to divergence from the classical Kansas surface layer curves. We compare the spectra for different typical meteorological conditions and katabatic wind maximum heights. It gives us insights on the extent of these perturbations regarding to the conditions. We test the influence of the nearness of the wind maximum on eddy covariance measurements and flux divergence in the few meters above the surface.

Litt, Maxime; Sicart, Jean-Emmanuel

2013-04-01

267

Response of debris-covered glaciers to climate change  

NASA Astrophysics Data System (ADS)

The presence of supraglacial debris strongly influences glacier ablation, and the mass balance of debris-covered glaciers differs significantly from that of clean glaciers in similar climatic settings. Predicting the response of debris-covered glaciers to climate change is important for hazard mitigation strategies in many high mountain environments, especially where temporary lakes are likely to form on stagnating glacier tongues. Accurate prediction of glacier evolution requires a robust mass balance function which incorporates the effect of debris cover. We present a new model for calculating ablation beneath supraglacial debris layer from meteorological data, based on coupling the surface energy balance and conductive heat flux through the debris layer. The model performs well in a wide range of climatic settings, and results correlate well with measured melt rates in the European Alps and Svalbard. The ablation model is used to construct theoretical mass balance curves for debris covered glaciers, providing surface boundary conditions for glacier flow models. Modelled mass balance curves display reverse gradients on glacier termini where the effect of thickening debris cover with decreasing altitude outweighs that of higher air temperatures. This explains the widely-noted tendency for debris-covered glaciers to stagnate under warming climates. When the mass balance of the glacier as a whole is negative, increasing ablation with altitude causes the lower tongue to decrease in gradient. As gradients and ice thicknesses decline, the process is reinforced by a positive feedback with velocity, so less ice is delivered to the terminal zone. Low surface gradients encourage the formation of supraglacial ponds which can grow rapidly, significantly increasing mass loss from the glacier and potentially posing flood hazards.

Benn, D. I.; Lindsey, N.; Kathryn, H.

2004-12-01

268

MODIS albedo and regional mass balance of high Arctic glaciers  

Microsoft Academic Search

MODIS albedo products are compared to glacier mass balance measured on eight glaciers in the high Arctic, in northwestern Svalbard. The glaciers range in size from ca. 5-500 km2. We use MODIS L3 albedo products (MOD43B3), which have a nominal resolution of 1 km, and for which data cover the spring to autumn months of 2000-2006. We compare the albedo

J. Kohler; G. Rotschky; I. Sobota; J. O. Hagen; W. Greuell

2007-01-01

269

Svalbard glacier elevation changes and contribution to sea level rise  

Microsoft Academic Search

We compare satellite altimetry from the Ice, Cloud, and Land Elevation Satellite (ICESat, 2003-2007) to older topographic maps and digital elevation models (1965-1990) to calculate long-term elevation changes of glaciers on the Svalbard Archipelago. Results indicate significant thinning at most glacier fronts with either slight thinning or thickening in the accumulation areas, except for glaciers that surged which show thickening

Christopher Nuth; Geir Moholdt; Jack Kohler; Jon Ove Hagen; Andreas Kb

2010-01-01

270

Svalbard glacier elevation changes and contribution to sea level rise  

Microsoft Academic Search

We compare satellite altimetry from the Ice, Cloud, and Land Elevation Satellite (ICESat, 20032007) to older topographic maps and digital elevation models (19651990) to calculate long-term elevation changes of glaciers on the Svalbard Archipelago. Results indicate significant thinning at most glacier fronts with either slight thinning or thickening in the accumulation areas, except for glaciers that surged which show thickening

Christopher Nuth; Geir Moholdt; Jack Kohler; Jon Ove Hagen; Andreas Kb

2010-01-01

271

Controlled Interferometric Modelling of Glacier Changes in South Svalbard  

Microsoft Academic Search

An original approach to geocoding and interpreting glacier interferograms with altimetric and photogrammetric constraints was designed and tested. New results demonstrating considerable glacier changes in South Svalbard were obtained through the joint analysis of ERS-1\\/2-SAR interferograms, ICESat-GLAS altimetry data and ASTER-VNIR imagery obtained over study glaciers in 1995\\/96, 2003 and 2004, respectively. Srkapp Land might become a separate island with

Aleksey I. Sharov; S. A. Osokin

2006-01-01

272

A review of the modern fluctuations of tropical glaciers  

Microsoft Academic Search

The tropical climate is characterized by a homogeneous atmosphere without frontal activity, a lack of thermal seasonality, and by one to two differently pronounced precipitation seasons. Consequently, tropical climate has a characteristic impact on tropical glaciers, with glacierclimate interactions different from those of the mid- and high-latitudes.The glaciers of tropical South America, Africa and New Guinea had a general maximum

Georg Kaser

1999-01-01

273

The new remote-sensing-derived Swiss glacier inventory  

Microsoft Academic Search

ABSTRACT. A new Swiss glacier inventory is to be compiled from satellite data for the year 2000.The study presented here describes two major tasks: (1) an accuracy assessment of different methods for glacier classificationwith LandsatThematic Mapper (TM) data and a digital elevation model,(DEM); (2) the geographical,information,system (GIS)-based methods for automatic extraction of individual glaciers from classified satellite data and the

Frank Paul; Andreas Kb; Max Maisch; Tobias Kellenberger; Wilfried Haeberli

274

Modelling mass balance and temperature sensitivity on Shallap glacier, Peru  

NASA Astrophysics Data System (ADS)

Due to pronounced dry seasons in the tropical Andes of Peru glacier melt water is an important factor for year-round water availability for the local society. Andean glaciers have been shrinking during the last decades but present day's magnitudes of glacier mass balance and sensitivities to changes in atmospheric drivers are not well known. Therefore we have calculated spatial distributed glacier mass and energy balance of Shallap glacier (4700 m - 5700 m, 9S), Cordillera Blanca, Peru, on hourly time steps for the period Sept. 2006 to Aug. 2008 with records from an AWS close to the glacier as model input. Our model evaluation against measured surface height change in the ablation zone of the glacier yields our model results to be reasonable and within an expectable error range. For the mass balance characteristics we found similar vertical gradients and accumulation area ratios but markedly differences in specific mass balance from year to year. The differences were mainly caused by large differences in annual ablation in the glacier area below 5000m. By comparing the meteorological conditions in both years we found for the year with more negative mass balance that total precipitation was only slightly lower but mean annual temperature was higher, thus the fraction of liquid precipitation and the snow line altitude too. As shortwave net energy turned out to be the key driver of ablation in all seasons the deviations in snow line altitude and surface albedo explain most of the deviations in available melt energy. Hence, mass balance of tropical Shallap glacier was not only sensitive to precipitation but also to temperature which has not been expected for glaciers in the Peruvian Andes before. We furthermore have investigated impacts of increasing temperature due to its multiple effects on glacier mass and energy balance (fraction of liquid precipitation, long wave incoming radiation, sensible and latent heat flux). Presenting these results should allow for better estimates of glacier evolution under changing climate conditions in the Peruvian Andes.

Gurgiser, W.; Marzeion, B.; Nicholson, L. I.; Ortner, M.; Kaser, G.

2013-12-01

275

Modelling changes in the mass balance of glaciers of the northern hemisphere for a transient 2CO 2 scenario  

Microsoft Academic Search

A climate forecast provided by a General Circulation Model (GCM), a glacier mass balance model and a glacier flow model is applied to a sample of 11 small glaciers. Another sample of six glaciers and six large, heavily glacierized areas in the arctic were modelled using only the climate forecast and the glacier mass balance model.The climate forecast of two

Christian Schneeberger; Heinz Blatter; Ayako Abe-Ouchi; Martin Wild

2003-01-01

276

How to implement data for improved modelling - Results from an extensive field campaign on the debris covered Lirung Glacier in the Nepalese Himalayas  

NASA Astrophysics Data System (ADS)

Debris covered glaciers have become a focus of current research because of growing evidence of an increase in debris cover associated with a warming climate and the effect that debris has on melt rates. Mass balance models increasingly aim at including the melt rate enhancing/reduction effect due to a thin/thick debris layer, respectively. However, knowledge about debris cover and thickness, its distribution and characteristics is limited and data are scarce, especially in the HKKH region where debris-covered glaciers are numerous. In this work we present a data set that is complementary to modelling efforts carried out to improve our understanding of processes occurring at the debris cover surface and how debris effects can be implemented into melt and mass balance models of different complexity. A key requirement for distributed melt modelling is the availability of debris cover and thickness maps and knowledge about characteristics of the debris layer and their spatial variability. An extensive field campaign was conducted from May to October 2012 on the debris covered Lirung Glacier in the Nepalese Himalayas. The collected data set consists of observations from an automatic weather station (AWS) measuring wind direction, wind speed, air and surface temperature, incoming and outgoing shortwave radiation, relative humidity and snow height, 14 sensors measuring 2 m air temperature and 7 surface temperature sensors, 3 temperature systems (tinytags) measuring temperature at the debris surface and the ice below the debris layer and one thermistors chain (with 8 temperature sensors) measuring the temperature profile in the debris layer. In the study region there is a key difference between meteorological conditions during monsoon and the dry period. We analyze separately all meteorological records for these different climatic conditions and show how temperature, albedo, relative humidity and wind speed and direction are affected. Wind speed and direction show similar diurnal behaviour but wind speed maxima are lower during monsoon. The relationship of air and surface temperature is constant across the glacier but different for monsoon and the dry period. Further, even though incoming and outgoing shortwave radiation obviously change during monsoon, albedo is only slightly affected. We compare the main spatio-temporal variability to that of variables recorded off-glacier. We show for example that the presence of the glacier dampens the monsoon impact on temperature lapse rates. We also investigate the conductivity of debris across the glacier to test its spatial consistency and use the temperature profile in the debris layer to test the commonly made assumption of linearity. We compare the calculated values with those provided in the literature both for the Himalaya and other mountainous regions. We finally discuss how these data can be used for possible applications and improvements of models.

Petersen, Lene; Immerzeel, Walter; Shahi, Sonika; Baral, Prashant; Pellicciotti, Francesca

2013-04-01

277

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

278

Glacier mass balance in Svalbard since 1912  

Microsoft Academic Search

Mass balance investigations on glaciers in Svalbard at high latitudes (78N) show that the ice masses have been steadily decreasing during the period 1950-1988. Detailed annual observations have been carried out on Braggerbreen since 1966 and Lovnbreen since 1967. The mean specific net balances are -0.43 m -i -l year and -0.35 m year water equivalent respectively. Only one year

J. O. HAGEN; B. LEFAUCONNIER

279

Observe how glaciers erode bedrock surfaces  

NSDL National Science Digital Library

In this interactive Earth science resource, students are first presented with six different photographs showcasing how glaciers can erode bedrock. Students are instructed to click on each labeled image to see an enlarged version of it. In the enlarged view, each photo is accompanied by a sentence or two that explains the glacial erosion shown. The images include features such as cirques, medial moraines, and striated bedrock. Copyright 2005 Eisenhower National Clearinghouse

Education, Terc. C.; Littell, Mcdougal

2003-01-01

280

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

281

Bacteria in Snow and Glacier Ice  

Microsoft Academic Search

By definition, the cryosphere is the portion of the Earth where water is in solid form as snow or ice. It includes vast areas\\u000a of sea ice, freshwater ice, glaciers, ice sheets, snow cover and permafrost. Because of the extremely harsh climatic conditions,\\u000a these frozen environments had been considered for a long time to be devoid of life or serving

Vanya Miteva

282

Little Ice Age glaciers in the Mediterranean mountains  

NASA Astrophysics Data System (ADS)

Only a few small glaciers survive today in the Mountains of the Mediterranean. Notable examples are found in the Pyrenees, Maritime Alps, Italian Apennines, the Dinaric and Albanian Alps and the mountains of Turkey. Many glaciers disappeared during the 20th Century. Glaciers were much larger and more numerous during the Little Ice Age (Hughes, 2014). Small glaciers even existed as far south as the High Atlas of Morocco and the Sierra Nevada of southern Spain. In more northerly areas, such as the western Balkans, glaciers and permanent snow patches occupied hundreds of cirques on relatively low-lying mountains. In the High Atlas and the Sierra Nevada no glaciers exist today, whilst in the Balkans only a few modern glaciers have been reported. A similar situation is apparent throughout the mountains of the Mediterranean region. New evidence for glacier change since the Little Ice Age will be published soon in Hughes (2014) and this paper reviews the extent, timing and climatic significance of Little Ice Age glaciation in the Mediterranean region. Reference: Hughes, P.D. (2014) Little Ice Age glaciers in the Mediterranean mountains. In: Carozza, J.-M., Devillers, B., Morhange, C. (eds) Little Ice Age in the Mediterranean, Mditerrane, volume 123.

Hughes, Philip

2014-05-01

283

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

284

How important are glaciers for Indus water resources?  

NASA Astrophysics Data System (ADS)

How important are glaciers for Indus water resources? Looking into the literature reveals a wide range of estimates to this question. They partly diverge because of different definitions of a 'water resource' and partly due to the different estimates of the contribution from the glaciers. Defining the Indus water resources as precipitation (rain and snowfall) minus the loss of water due to evapotranspiration and sublimation for non-glaciated regions and the total runoff from the glaciated regions (sum of seasonal snowmelt on top of the glacier, percolating rainfall and loss of glacier ice), we have attempted to estimate the fraction of the total water resource that is coming from the glaciated regions and the fraction due to loss of glacier ice alone (which is the part that may be lost if a glacier disappears). Here we present estimates of water resources from non-glaciated regions using a wide range of estimates from observationally based, reanalysis and land data assimilation systems. Our results indicate large differences between the different estimates even for the annual values averaged over the whole basin. The implication of this finding is that the large uncertainties in the water resources of the non-glaciated regions will prevent us from making narrow estimates of the importance of the glaciers. For estimating the contribution from the glaciers we use an energy balance model with snow metamorphosis forced with 3 hourly reanalysis data (including perturbed precipitation and temperature runs based on the uncertainties in temperature and precipitation found from 10 different datasets). As there is over 10 000 glaciers in Indus it is not possible to model individual glaciers. Instead we model ';representative' glaciers where we get the average elevation of terminus and top, avg. glacier depth etc. from the Extended World Glacier Inventory in a given sub basin (using the FAO HydroSHEDS dataset to divide the Indus basin into subbasins). The mass balance and glacier runoff is then calculated for every 50 m elevation of the ';representative' glacier and the results scale up with total glacier area of that subbasin to get the total mass balance and glacier runoff for the subbasin. This is done for all subbasins that have glaciers. Our results using the above approach indicate that runoff from glaciated areas contributes to 8-24% of the Indus water resources, but ice melt alone only accounts for 2-10% the rest is seasonal snowmelt on top of the glacier and percolation of rain through the glacier. Thus if all glaciers are lost the effect on the water resources of the Indus basin will probably be less than 10%. We found the key uncertainties in estimating Indus water resources to be the lack of observations of precipitation. While the rate of sublimation from the glacier is a key factor in estimating how much of the glacier loss that actually becomes runoff. A factor often ignored or just prescribed as a constant factor when simple degree day models are used.

Sorteberg, A.

2013-12-01

285

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

286

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

USGS Publications Warehouse

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

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

2008-01-01

287

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

USGS Publications Warehouse

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

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

1979-01-01

288

New Species in New Guinea / Melting Glaciers  

NSDL National Science Digital Library

The first segment of this radio broadcast discusses a recent expedition to the isolated Foja mountain range in western New Guinea, which has discovered several new species of birds, 20 new frog species, and four new butterfly species, as well as a rare bird which had not been seen for sixty years, and unusual plants. One of the explorers discusses the efforts to map the diversity of the island and the challenges in preserving such ecological treasures. This segment is 12 minutes and 21 seconds in length. The second segment consists of a conversation with researchers who travel the world documenting the retreat of mountain glaciers. Topics include efforts to build a global database of ice cores to document changes; a discussion of increased water flow from glaciers; the logistics of drilling ice cores at high altitude and moving them to a university lab; how annual snowfall is recorded in ice cores; and how retreating glaciers are exposing plants that were covered for six thousand years. This segment is 35 minutes and 20 seconds in length.

289

Recent acceleration of glacier thinning in Svalbard  

NASA Astrophysics Data System (ADS)

Geodetic data comprising archive maps, contemporary lidar, and photogrammetric digital elevation models show that the rate of volume loss of two Svalbard glaciers, Midtre Lovnbreen (ML) and Slakbreen (SL), has accelerated in recent years. At ML, the thinning rate as averaged over the whole glacier has increased steadily over the latter part of the 20th century. The mean thinning rate for 1995-2003 is more than double that of the first measurement epoch 1962-1977, while for the relatively short time-span 2003-2005 it is over three times that of the first epoch. The glacier thinning rate averaged along the centerline is 0.65 m a-1 for 1995-2003 at ML, while for the comparable epoch on SL (1990-2003) it is 0.74 m a-1. These are significantly greater centerline thinning rates than have been presented previously. However, our findings are consistent with the most recent GRACE measurements, which show an increasing mass loss over Svalbard, as well as with gravity and surface deformation data from Ny-{}lesund, which indicate contemporary uplift rates equivalent to 0.75 m a-1 when attributed to ice mass alone.

Kohler, J.; James, T. D.; Murray, T.; Nuth, C.; Brandt, O.; Barrand, N. E.; Aas, H. F.; Luckman, A.

2006-12-01

290

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

291

Figure 1. Wind and tides mix the ocean to great depths. Thus, because of the thermal inertia of this ocean water, it requires at least several decades for the ocean temperature to respond fully to a climate  

E-print Network

1 Figure 1. Wind and tides mix the ocean to great depths. Thus, because of the thermal inertia of this ocean water, it requires at least several decades for the ocean temperature to respond fully to a climate forcing. Can we defuse The Global Warming Time Bomb? All glaciers in Glacier National Park

Glashausser, Charles

292

Four years of mass balance on Chhota Shigri Glacier, Himachal Pradesh, India, a new benchmark glacier in the western Himalaya  

Microsoft Academic Search

Little is known about the Himalayan glaciers, although they are of particular interest in terms of future water supply, regional climate change and sea-level rise. In 2002, a long-term monitoring programme was started on Chhota Shigri Glacier (32.2N, 77.5E; 15.7 km2, 6263-4050 m a.s.l., 9 km long) located in Lahaul and Spiti Valley, Himachal Pradesh, India. This glacier lies in

Patrick Wagnon; Anurag Linda; Yves Arnaud; Rajesh Kumar; Parmanand Sharma; Christian Vincent; Jose George Pottakkal; Etienne Berthier; Alagappan Ramanathan; Syed Iqbal Hasnain; Pierre Chevallier

2007-01-01

293

Remote sensing of glacier change in West Greenland: accounting for the occurrence of surge-type glaciers  

Microsoft Academic Search

Automated glacier mapping from thresholded band ratios of multispectral satellite data is a well-established technique to update glacier inventories over large and remote regions. The local glaciers and ice caps on Greenland are of particular interest for such efforts, as they have been only partly mapped, mainly during the 1940s-60s, and their potential contribution to global sea-level rise could be

Michele CITTERIO; Frank PAUL; Andreas P. AHLSTRM; Hans F. JEPSEN; Anker WEIDICK

2009-01-01

294

Debris Covered Glaciers: Melt Modeling and Characterization  

NASA Astrophysics Data System (ADS)

Debris-covered glaciers occur in many mountainous regions throughout the world. Melt water from these glaciers is important for nearby populations, e.g. for hydropower and drinking water, however it can also be potentially dangerous in the form of a glacial lake outburst flood (GLOF). Accurate melt models are needed to calculate present and future mass balance of debris-covered glaciers. One widely used method assumes a constant 24-hour thermal gradient (CTG), although this approach remains largely untested. We assess the physical basis of the CTG method using a fully time-dependent 1-dimensional heat flux model and field data from Longyear Glacier, Svalbard, gathered during the 2010 melt season. An indirect correlation between debris thickness and linearity of the average daily temperature profile has been found. Melt rates modeled using the CTG method show a convergence with the results using our full physically based model for debris thickness > 0.5m. For debris thicknesses < 0.5m the CTG method calculates melt rates as low as twice the physical model. These differences arise out of the CTG method's assumption of a constant thermal gradient with depth as well as a 0C debris-ice interface. Results have shown that only under stable weather conditions does the average daily debris thermal gradient approach constant. Furthermore, in reality the debris-ice interface undergoes higher temperatures than those calculated by the CTG method and it is only with increasing debris thickness that the two converge. The model was also used to generate an strem curve for the Longyear Glacier. Three strem curves were generated using data from early, peak and late melt to assess the differences that may arise from using data from only a small part of the melt season. Curves calculated from data collected during early and late melt season are very similar to the full season curve whereas the curve generated using data from the peak of the melt season overestimates daily melt rates by up to double. The results have significant implications when using strem curves to compare glacial sub-debris melt rates.

Mertes, J. R.; Benn, D.

2011-12-01

295

A note on the water budget of temperate glaciers  

NASA Astrophysics Data System (ADS)

In this note the total dissipative melting in temperate glaciers is studied. The analysis is based on the notion that the dissipation is determined by the loss of potential energy, due to the downward motion of mass (ice, snow, meltwater and rain). A mathematical formulation of the dissipation is developed and applied to a simple glacier geometry. In a next step, meltwater production resulting from enhanced ice motion during a glacier surge is calculated. The amount of melt energy available follows directly from the lowering of the centre of gravity of the glacier. To illustrate the concept, schematic calculations are presented for a number of glaciers with different geometric characteristics. Typical dissipative melt rates, expressed as water-layer depth averaged over the glacier, range from a few cm per year for smaller glaciers to half a meter per year for Franz-Josef Glacier, one of the most active glaciers in the world (in terms of mass turnover). The total generation of meltwater during a surge is typically half a meter. For Variegated Glacier a value of 70 cm is found, for Kongsvegen 20 cm. These values refer to water layer depth averaged over the entire glacier. The melt rate depends on the duration of the surge. It is generally an order of magnitude larger than the water production by "normal" dissipation. On the other hand, the additional basal melt rate during a surge is comparable in magnitude to the water input from meltwater and precipitation. This suggests that enhanced melting during a surge does not grossly change the total water budget of a glacier. Basal water generated by enhanced sliding is an important ingredient of many theories of glacier surges. It provides a positive feedback mechanism that actually makes the surge happen. The results found here suggest that this can only work if water generated by enhanced sliding is accumulating in a part of the glacier base where surface meltwater and rain has no or very limited access. This finding seems compatible with the fact that on many glaciers surges are initiated in the lower accumulation zone.

Oerlemans, J.

2013-06-01

296

A note on the water budget of temperate glaciers  

NASA Astrophysics Data System (ADS)

In this note, the total dissipative melting in temperate glaciers is studied. The analysis is based on the notion that the dissipation is determined by the loss of potential energy due to the downward motion of mass (ice, snow, meltwater and rain). A mathematical formulation of the dissipation is developed and applied to a simple glacier geometry. In the next step, meltwater production resulting from enhanced ice motion during a glacier surge is calculated. The amount of melt energy available follows directly from the lowering of the centre of gravity of the glacier. To illustrate the concept, schematic calculations are presented for a number of glaciers with different geometric characteristics. Typical dissipative melt rates, expressed as water-layer depth averaged over the glacier, range from a few centimetres per year for smaller glaciers to half a metre per year for Franz Josef Glacier, one of the most active glaciers in the world (in terms of mass turnover). The total generation of meltwater during a surge is typically half a metre. For Variegated Glacier a value of 70 cm is found, for Kongsvegen 20 cm. These values refer to water layer depth averaged over the entire glacier. The melt textit{rate} depends on the duration of the surge. It is generally an order of magnitude greater than water production by `normal' dissipation. On the other hand, the additional basal melt rate during a surge is comparable in magnitude with the water input from meltwater and precipitation. This suggests that enhanced melting during a surge does not grossly change the total water budget of a glacier. Basal water generated by enhanced sliding is an important ingredient in many theories of glacier surges. It provides a positive feedback mechanism that actually makes the surge happen. The results found here suggest that this can only work if water generated by enhanced sliding accumulates in a part of the glacier base where surface meltwater and rain have no or very limited access. This finding seems compatible with the fact that, on many glaciers, surges are initiated in the lower accumulation zone.

Oerlemans, J.

2013-09-01

297

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

298

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

299

Energy balance of a glacier surface: Analysis of automatic weather station data from the Morteratschgletscher, Switzerland  

NASA Astrophysics Data System (ADS)

We describe and analyze a complete 1-yr data set from an automatic weather station (AWS) located on the snout of the Morteratschgletscher, Switzerland. The AWS stands freely on the glacier surface and measures pressure, windspeed, wind direction, air temperature and humidity, incoming and reflected solar radiation, incoming and outgoing longwave radiation, snow temperature, and change in surface height (giving melt rates and snow accumulation). The wind is downglacier most of the time. As expected for a flow of katabatic origin, for air temperatures above the melting point we find a correlation between windspeed and temperature. We evaluate all significant components of the surface energy flux. For a (constant) turbulent exchange coefficient of 0.00153 (reference height 3.5 m) we obtain a perfect match between calculated and measured ice melt. The sensible heat flux is positive (towards the glacier surface) all the time with the largest values on fine summer days (daily mean values are typically 100 W m(-2) on the warmest days). The latent heat flux is small and negative in winter. In summer it is mainly positive (condensation), but negative values also occur. Altogether about 75% of the melt energy is supplied by radiation (shortwave and longwave) and 25% by the turbulent fluxes.

Oerlemans, J.; Klok, E. J.

2002-11-01

300

Harnessing Wind  

NSDL National Science Digital Library

Students are introduced to the ways that engineers study and harness the wind. They learn about the different kinds of winds and how to measure wind direction. In addition, they learn how air pressure creates winds and how engineers design and test wind turbines to harness renewable wind energy.

Integrated Teaching And Learning Program

301

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

302

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.

303

GLACIODYN - The dynamic response of Arctic glaciers to global warming  

Microsoft Academic Search

The aim of GLACIODYN is to reduce the uncertainties in Arctic Glaciers and Ice Cap (GIC) contribution to sea level changes. This involves to include calving in mass budget calculations, improve process understanding of calving and basal sliding and include dynamics in modeling of future glacier response. Selected target GICs have been studied in the Arctic. In this presentation we

J. M. Hagen; T. Dunse; T. Eiken; J. Kohler; G. Moholdt; C. Nuth; T. Schuler; M. Sund

2009-01-01

304

DEM quality assessment for quantification of glacier surface change  

Microsoft Academic Search

Photogrammetric digital elevation models (DEMs) are often used to derive and monitor surfaces in inaccessible areas. They have been used to monitor the spatial and temporal change of glacier surfaces in order to assess glacier response to climate change. However, deriving photogrammetric DEMs of steep mountainous topography where the surface is often obscured by regions of deep shadow and snow

Addy Pope; Tavi Murray; Adrian Luckman

2007-01-01

305

Large fluctuations in speed on Greenland's Jakobshavn Isbr glacier  

Microsoft Academic Search

It is important to understand recent changes in the velocity of Greenland glaciers because the mass balance of the Greenland Ice Sheet is partly determined by the flow rates of these outlets. Jakobshavn Isbr is Greenland's largest outlet glacier, draining about 6.5 per cent of the ice-sheet area, and it has been surveyed repeatedly since 1991 (ref. 2). Here we

Ian Joughin; Waleed Abdalati; Mark Fahnestock

2004-01-01

306

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

307

Visualizing Glaciers and Sea Ice via Google Earth  

Microsoft Academic Search

The NOAA team at NSIDC manages over 60 distinct cryospheric and related data products. With an emphasis on data rescue and in situ data, these products hold value for both the scientific and non-scientific user communities. The overarching goal of this presentation is to promote products from two components of the cryosphere (glaciers and sea ice). Our Online Glacier Photograph

L. M. Ballagh; F. Fetterer; T. M. Haran; K. Pharris

2006-01-01

308

Sierra Nevada Rock Glaciers: Biodiversity Refugia in a Warming World?  

Microsoft Academic Search

Rock glaciers and related periglacial rock-ice features (RIFs) are common landforms in high, dry mountain ranges, and widely distributed throughout canyons of the Sierra Nevada, California, USA (Millar & Westfall, in press). Due to insulating rock carapaces, active rock glaciers (ice-cored) have been documented to maintain ice longer, and thus contribute to more enduring hydrologic output, under past warming climates

C. I. Millar; R. D. Westfall

2007-01-01

309

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

NSDL National Science Digital Library

This video shows how a NASA glaciologist has learned about glaciers and how their formation could be related to climate change. It features nine fly-bys over 3-dimensional glaciers, live video footage of ice fronts calving into the sea, and picture sequences of historical and satellite data.. Length:13:15.

1996-01-01

310

Muir and Riggs Glaciers, Muir Inlet, Alaska - 2004  

USGS Multimedia Gallery

The second repeat photograph documents significant changes that have occurred during the 63 years between photographs A and C, and during the 54 years between photographs B and C. Muir Glacier has retreated out of the field of view and is now more than 7 kilometers northwest. Riggs Glacier has retre...

311

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.

312

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

313

ENVIRONMENTAL HAZARDS OF AVALANCHES: PRELIMINARY RESEARCH IN GLACIER NATIONAL  

E-print Network

ENVIRONMENTAL HAZARDS OF AVALANCHES: PRELIMINARY RESEARCH IN GLACIER NATIONAL PARK Site Focus: Balu Pass, Glacier National Park, B.C. Avalanche path near Balu Pass. (Photo Courtesy of: www in avalanche areas? #12;Researchers · Ben Ferrel · Keri Laughlin · Kevin McPhedran · Mark Brown · also thanks

Smith, Dan

314

Forecasting temperate alpine glacier survival from accumulation zone observations  

Microsoft Academic Search

Temperate alpine glacier survival is dependent on the consistent presence of an accumulation zone. Frequent low accumulation area ratio values, below 30%, indicate the lack of a consistent accumulation zone, which leads to sub- stantial thinning of the glacier in the accumulation zone. This thinning is often evident from substantial marginal recession, emergence of new rock outcrops and surface elevation

M. S. Pelto

2010-01-01

315

Forecasting temperate alpine glacier survival from accumulation zone observations  

Microsoft Academic Search

Temperate alpine glacier survival is dependent on the consistent presence of an accumulation zone. Frequent low accumulation area ratio values, below 30%, indicate the lack of a consistent accumulation zone, which leads to substantial thinning of the glacier in the accumulation zone. This thinning is often evident from substantial marginal recession, emergence of new rock outcrops and surface elevation decline

M. S. Pelto

2010-01-01

316

Forecasting temperate alpine glacier survival from accumulation zone observations  

NASA Astrophysics Data System (ADS)

Temperate alpine glacier survival is dependent on the consistent presence of an accumulation zone. Frequent low accumulation area ratio values, below 30%, indicate the lack of a consistent accumulation zone, which leads to substantial thinning of the glacier in the accumulation zone. This thinning is often evident from substantial marginal recession, emergence of new rock outcrops and surface elevation decline in the accumulation zone. In the North Cascades 9 of the 12 examined glaciers exhibit characteristics of substantial accumulation zone thinning; marginal recession or emergent bedrock areas in the accumulation zone. The longitudinal profile thinning factor, f, which is a measure of the ratio of thinning in the accumulation zone to that at the terminus, is above 0.6 for all glaciers exhibiting accumulation zone thinning characteristics. The ratio of accumulation zone thinning to cumulative mass balance is above 0.5 for glacier experiencing substantial accumulation zone thinning. Without a consistent accumulation zone these glaciers are forecast not to survive the current climate or future additional warming. The results vary considerably with adjacent glaciers having a different survival forecast. This emphasizes the danger of extrapolating survival from one glacier to the next.

Pelto, M. S.

2010-01-01

317

GIS-based modelling of (all) glacier beds in Switzerland  

Microsoft Academic Search

Due to the ongoing and expected future increase in global mean temperature, the Alpine environment will continue to get further away from equilibrium. Glaciers are a part of the high-mountain cryosphere, and their changes are considered to be the best natural indicators of climatic changes. The calculation and visualization of future glacier development is thus an important task of communicating

A. Linsbauer; F. Paul; M. Hoelzle; W. Haeberli

2009-01-01

318

Annual Mass and Energy Exchange on the Blue Glacier  

Microsoft Academic Search

Field work and techniques of observation at the IGY station at 2010 meters eleva- tion on the Blue Glacier, Mount Olympus, western Washington State, are briefly described. The annual mass exchange on this glacier is large. Only very shallow penetration of subfreezing temperatures occurs, and the winter energy deficit is due almost entirely to increased ice mass. The 1958 ablation

E. Lachapelle

1959-01-01

319

Neural Networks Applied to Estimating Subglacial Topography and Glacier Volume  

Microsoft Academic Search

To predict the rate and consequences of shrinkage of the earth's mountain glaciers and ice caps, it is necessary to have improved regional-scale models of mountain glaciation and better knowledge of the subglacial topography upon which these models must operate. The problem of estimating glacier ice thickness is addressed by developing an artificial neural network (ANN) approach that uses calculations

Garry K. C. Clarke; Etienne Berthier; Christian G. Schoof; Alexander H. Jarosch

2009-01-01

320

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.

321

Numerical simulations of Gurenhekou glacier on the Tibetan Plateau  

E-print Network

using an empirical relationship between glacier and temperature rise since the Little Ice Age, finding that subcontinental glaciers would lose $48% of their volume by 2100 under a 38C temperature rise scenario. However requires use of such a flow model. We parameterize the temperature and surface mass-balance (SMB

Moore, John

322

Greenland outlet glacier dynamics from Extreme Ice Survey (EIS) photogrammetry  

NASA Astrophysics Data System (ADS)

Time Lapse cameras fill gaps in our observational capabilities: 1. By providing much higher temporal resolution than offered by conventional airborne or satellite remote sensing. 2. While GPS or auto-theodolite observations can provide higher time resolution data than from photogrammetry, survival of these instruments on the hazardous glacier surface is limited, plus, the maintenance of such systems can be more expensive than the maintenance of a terrestrial photogrammetry installation. 3. Imagery provide a high spatial density of observations across the glacier surface, higher than is realistically available from GPS or other in-situ observations. 4. time lapse cameras provide observational capabilities in Eulerian and Lagrangian frames while GPS or theodolite targets, going along for a ride on the glacier, provide only Lagrangian data. Photogrammetry techniques are applied to a year-plus of images from multiple west Greenland glaciers to determine the glacier front horizontal velocity variations at hourly to seasonal time scales. The presentation includes comparisons between glacier front velocities and: 1. surface melt rates inferred from surface air temperature and solar radiation observations; 2. major calving events identified from camera images; 3. surface and near-surface ocean temperature; 4. land-fast sea ice breakup; 5. tidal variations; 6. supra-glacial melt lake drainage events observed in daily optical satellite imagery; and 7.) GPS data. Extreme Ice Survey (EIS) time lapse camera overlooking the Petermann glacier, installed to image glacier dynamics and to capture the predicted ice "island" detachment.

Hawbecker, P.; Box, J. E.; Balog, J. D.; Ahn, Y.; Benson, R. J.

2010-12-01

323

Mass balance of Vatnajokull outlet glaciers reconstructed back to 1958  

E-print Network

Mass balance of Vatnaj¨okull outlet glaciers reconstructed back to 1958 L. A. Rasmussen Department seasonal components of mass balance of five Vatnaj¨okull outlet glaciers. Over the period of observations of mass balance between 1991 and 2001, it had percentage r2 rang- ing from 41 to 93 for winter balance bw

Rasmussen, L.A.

324

LINKING THE WEATHER TO GLACIER HYDROLOGY AND MASS BALANCE AT PEYTO GLACIER  

Microsoft Academic Search

Attempts have been made to link weather variations at Peyto Glacier to mass balance fluctuations. On the larger scale of inquiry, associations have been found between seasonal components of the mass balance and synoptic weather types. Also, there are significant correlations with temperature and precipitation records from regional weather stations. The smaller scale of study features micro-meteorological investigations to document

D. Scott Munro

325

Seasonal Variation in Ablation and Surface Velocity on a Temperate Maritime Glacier: Fox Glacier, New Zealand  

Microsoft Academic Search

Seasonal variations in ablation and surface velocity were investigated on the lower part of Fox Glacier, South Westland, New Zealand. A large variation between summer and winter ablation was recorded, with daily averages of 129 mm d21 and 22 mm d21, respectively. Variations in measured climatic variables were found to account for ,90% of variation in ablation during both summer

H. L. Purdie; M. S. Brook; I. C. Fuller

2008-01-01

326

Yeast and yeast-like diversity in the southernmost glacier of Europe (Calderone Glacier, Apennines, Italy).  

PubMed

The present study reports the characterization of psychrophilic yeast and yeast-like diversity in cold habitats (superficial and deep sediments, ice cores and meltwaters) of the Calderone Glacier (Italy), which is the southernmost glacier in Europe. After incubation at 4 and 20 degrees C, sediments contained about 10(2)-10(3) CFU of yeasts g(-1). The number of viable yeast cells in ice and meltwaters was several orders of magnitude lower. The concomitant presence of viable bacteria and filamentous fungi has also been observed. In all, 257 yeast strains were isolated and identified by 26S rRNA gene D1/D2 and internal transcribed spacers (1 and 2) sequencing as belonging to 28 ascomycetous and basidiomycetous species of 11 genera (Candida, Cystofilobasidium, Cryptococcus, Dioszegia, Erythrobasidium, Guehomyces, Mastigobasidium, Mrakia, Mrakiella, Rhodotorula and Sporobolomyces). Among them, the species Cryptococcus gastricus accounted for almost 40% of the total isolates. In addition, 12 strains were identified as belonging to the yeast-like species Aureobasidium pullulans and Exophiala dermatitidis, whereas 15 strains, presumably belonging to new species, yet to be described, were also isolated. Results herein reported indicate that the Calderone Glacier, although currently considered a vanishing ice body due to the ongoing global-warming phenomenon, still harbors viable psychrophilic yeast populations. Differences of yeast and yeast-like diversity between the glacier under study and other worldwide cold habitats are also discussed. PMID:20402775

Branda, Eva; Turchetti, Benedetta; Diolaiuti, Guglielmina; Pecci, Massimo; Smiraglia, Claudio; Buzzini, Pietro

2010-06-01

327

Mapping the retreat of the Asulkan Glacier in Glacier National Park, British Columbia  

E-print Network

· Dendrochronology with Jacolby · Dendroclimatology with Markus and Kyla · Lichenometry with Erin · Moraine #12;190520071918 #12;Site Map #12;DendrochronologyDendrochronology #12;Dendrochronology · Tree age lichen size and proximity to glacier snout. #12;Moraine Interpretation 3 Approaches: · Dendrochronology

Smith, Dan

328

Mapping the Retreat of the Asulkan Glacier in Glacier National Park, British Columbia, Canada  

E-print Network

, five dating techniques were applied: lichenometry, dendrochronology, moraine interpretation. This data was used in support of the dendrochronology results for the purposes of mapping retreat. Surveys with the other dating techniques, enabled us to map the Asulkan glacier's gradual recession. Dendrochronology

Smith, Dan

329

Estimating the risk of glacier cavity collapse during artificial drainage: The case of Tte Rousse Glacier  

NASA Astrophysics Data System (ADS)

During the summer of 2010, the presence of a pressurized water-filled subglacial-cavity of at least 50,000 m3 was detected within the Tte Rousse Glacier (French Alps). Artificial drainage was started to avoid an uncontrolled rupture of the ice dam, but was interrupted soon after to evaluate the capacity of the cavity-roof to bear itself. The risk was that the release of pressure within the cavity during the artificial drainage would precipitate the collapse of the cavity roof and potentially flush out the remaining water flooding the valley below. An unprecedented modeling effort was deployed to answer the question of the cavity roof stability. We set up a model of the glacier with its water cavity, solved the three-dimensional full-Stokes problem, predicted the upper surface and cavity surface displacements for various drainage scenarios, and quantified the risk of the cavity failure during artificial drainage. We found that the maximum tensile stress in the cavity roof was below the rupture value, indicating a low risk of collapse. A post drainage survey of the glacier surface displacements has confirmed the accuracy of the model prediction. This practical application demonstrates that ice flow models have reached sufficient maturity to become operational and assist policy-makers when faced with glaciological hazards, thus opening new perspectives in risk management of glacier hazards in high mountain regions.

Gagliardini, O.; Gillet-Chaulet, F.; Durand, G.; Vincent, C.; Duval, P.

2011-05-01

330

Ice Cliffs and the Terminus Dynamics of Polar Glaciers  

NASA Astrophysics Data System (ADS)

Polar glaciers that terminate on land have a terminus morphology contrasting with lower latitude glaciers: polar glaciers terminate in dramatic ice cliffs, typically 30 meters high. These ice cliffs are one unique manifestation of the balance among the glacial processes of deformation, ablation (sublimation and melt), and calving. Because each of these glacial processes depends on environmental conditions, the terminus morphology reflects the local conditions and will change as conditions change in the future. This relationship, ultimately, affects moraine formation and the response of a glacier's terminus to changes in climate. We developed a simple model, emphasizing the key processes active at a glacier terminus (ice deformation, calving, and ablation), to study the variation of terminus morphology, with a particular emphasis on the ice-cliff morphology of polar glaciers. Each of these processes depends on the thickness and slope of ice near the terminus (the height of an ice cliff); and, through feedbacks, different conditions lead to various stable and unstable morphologies. We tuned our model with observations from two polar glaciers that terminate in ice cliffs on land: Taylor Glacier in the Dry Valleys of Antarctica and Red Rock Ice Cliffs of the Greenland Ice Sheet (near Nunatarssuaq), then run a series of experiments to explore the balance of processes that lead to steep ice cliffs in some environments, but gradually sloping termini in others. We present results for the stability of the ice cliff morphology under different environmental conditions ranging from the extreme cold environment on Mars to temperate glaciers on Earth. We found that ice cliffs are a stable morphology in polar climates for both advancing and retreating glaciers, while temperate glaciers can maintain a steep terminus only under conditions causing fast advance or if they terminate on a steep slope. Glacier termini have always presented a challenge to our understanding and modeling of the behavior of glaciers. This is because many of the normal simplifying assumptions of glacier flow breakdown (i.e. longitudinal stresses are no longer negligible at the terminus). Our model provides a simple method for incorporating terminus behavior into advance and retreat models.

Pettit, E. C.; Nylen, T. H.; Fountain, A. G.; Hallet, B.

2006-12-01

331

Bathymetric control of tidewater glacier mass loss in northwest Greenland  

NASA Astrophysics Data System (ADS)

It has been suggested that fjord geometry could be an important contributor to the observed mass loss variability in Greenland by modulating the flow of warm water to marine-terminating glaciers. New gravity-derived bathymetry of Greenlandic fjords confirms the link between the grounding line depth and rates of glacier mass loss, a relationship previously predicted only in ice models. We focus on two neighboring glaciers to minimize differences in external forcing and therefore isolate the role of the fjord bathymetry. Tracy Glacier has a deeper grounding line and has been retreating since 1892 with a contemporary mass budget of -1.63 Gt a-1. Heilprin Glacier has a shallower grounding line depth, a stable ice terminus, and a mass budget of only -0.53 Gt a-1. Because of its deeper grounding line, Tracy has more ice in contact with warm subsurface water, leaving it more vulnerable to changes in ocean forcing and therefore mass loss.

Porter, David F.; Tinto, Kirsty J.; Boghosian, Alexandra; Cochran, James R.; Bell, Robin E.; Manizade, Serdar S.; Sonntag, John G.

2014-09-01

332

Planetary science: are there active glaciers on Mars?  

PubMed

Head et al. interpret spectacular images from the Mars Express high-resolution stereo camera as evidence of geologically recent rock glaciers in Tharsis and of a piedmont ('hourglass') glacier at the base of a 3-km-high massif east of Hellas. They attribute growth of the low-latitude glaciers to snowfall during periods of increased spin-axis obliquity. The age of the hourglass glacier, considered to be inactive and slowly shrinking beneath a debris cover in the absence of modern snowfall, is estimated to be more than 40 Myr. Although we agree that the maximum glacier extent was climatically controlled, we find evidence in the images to support local augmentation of accumulation from snowfall through a mechanism that does not require climate change on Mars. PMID:16340962

Gillespie, Alan R; Montgomery, David R; Mushkin, Amit

2005-12-01

333

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

334

Timing of Holocene Glacier Recessions in the Swiss Alps  

NASA Astrophysics Data System (ADS)

Alpine glaciers are sensitive climate indicators on time scales as short as decades to centuries. Periods of cold and wet climatic conditions cause glacial advances and deposition of moraines. Subsequent change to warmer and drier conditions cause glacial recessions. Since the cold event of the Little Ice Age glaciers in the Swiss Alps have retreated substantially exposing high walls of lateral moraines which consist of a stack of overlying till units. Previous work focused on such stacked moraines and the related glacial advances. However, such paleoclimatic reconstructions based only on moraines are incomplete, in particular for periods of glacial recession. This study examines Holocene glacier recessions based on pieces of wood and peat occurring in glaciofluvial deposits of outburst flood events. These subfossil remains indicate that (i) glaciers were once smaller than present, (ii) climate conditions allowed vegetation growth and a higher treeline elevation than today, (iii) sequences of glaciofluvial gravels and lodgement tills accumulated in now glaciated basins. We focus in this study on three climaticly different re-gions: i.e. Unteraar Glacier (Central Alps), Tschierva Glacier (Eastern Alps) and Ried Glacier (South Central Alps). The conventional radiocarbon and AMS dating was used to determine the age of more than 140 samples of wood and peat fragments. The results show that glacier recessions occurred in distinct phases throughout the Holocene, synchronously in different Alpine regions. The total duration of recession phases is longer than 5500 yr or > 50 % of the Holocene epoch. The glacial recessions are separated by glacial advances, which occurred in time periods shorter than 400 yr. A comparison of our Holocene record of glacier length variations with the ice rafted debris events in the North Atlantic, the Be-10 record of ice cores and atmospheric ? 14C suggest a combination of solar and North Atlantic forcing. Thus, situations of glacial recession, to the extent of smaller glaciers than present, occurred throughout the Holocene.

Joerin, U. E.; Stocker, T. F.; Schluechter, C.

2004-12-01

335

Photogrammetric Monitoring of Glacier Margin Lakes  

NASA Astrophysics Data System (ADS)

The growing number of glacial margin lakes that have developed due to glacier retreat, have caused an increase of dangerous Glacial Lake Outburst Floods (GLOFs) in several regions over the last decade. A GLOF can occur when the water from the lake finds a path underneath the bottom of the glacier and the lake is draining rapidly. This causes normally a flood wave downstream the glacier. Typically such an event takes about 24 hours. GLOF scenarios may be a significant hazard to life, property, nature and infrastructure in the affected areas. Together with our partner institute CECS (Valdivia, Chile), a project was initiated on a pilot study for an early warning system for GLOF events in the Northern Patagonian Icefield. A GLOF is normally characterized by a progressive water level drop. By observing the water level of the lake, an imminent GLOF-event can be identified. Common gauging systems are not suitable for the measurement task, as they may be affected by ice fall or landslides in the lake basin. Therefore, in our pilot study the water level is observed by processing images of a terrestrial camera system. The paper presents the basic principle of a single-camera based GLOF early warning system. Challenges and approaches to solve them are discussed. First results from processed image sequences are presented to show the feasibility of the concept. Water level changes can be determined at decimetre precision. In the first stage of the project, the waterline was measured manually in the images. A promising approach for reliable automation of this task is the use of a camera, which is sensitive for near infrared. The difference in the reflection of water, ice, and rock in this wavelength is more better than in RGB. This will be discussed in the outlook in deep.

Mulsow, C.; Koschitzki, R.; Maas, H.-G.

2013-01-01

336

Good for glaciers, bad for people? Archaeologically relevant climate models developed from reconstructions of glacier mass balance  

Microsoft Academic Search

We present a new climate and vegetation model, and discuss applications with a study of medieval land degradation and settlement abandonment in rsmrk, Iceland. Existing meteorological data are used as the starting point for modelling glacier snowlines (equilibrium lines), and this is developed to model seasonal snowcover, potential vegetation and growing season. The current status and past fluctuations of glaciers

Andrew F. Casely; Andrew J. Dugmore

2007-01-01

337

Distributed glacier mass-balance modelling as an important component of modern multi-level glacier monitoring  

Microsoft Academic Search

Modern concepts of worldwide glacier monitoring include numerical models for (1) interconnecting the different levels of observations (local mass balance, representative length change, glacier inventories for global coverage) and (2) extrapolations in space (coupling with climate models) and time (backward and forward). In this context, one important new tool is distributed mass-balance modelling in complex mountain topography. This approach builds

Horst Machguth; Frank Paul; Martin Hoelzle; Wilfried Haeberli

2006-01-01

338

Counting Glaciers: Use of Scaling Methods to Estimate the Number and Size Distribution of the Glaciers of the World  

Microsoft Academic Search

Global aqd regional syntheses of glacier melt and runoff are needed for under- standing present and future sea-level rise, as well as for hydrological and climato- logical analyses. Observational data on glacier areas are needed for modeling gla- cier-climate interactions and runoff, but are available for only a few regions. Data on the distributions of sizes and thicknesses are critical

M. F. MEIER; D. B. BAHR

339

Welcome to GLACIER Tax Prep We hope you find GLACIER Tax Prep simple to use and easy to understand!  

E-print Network

simple steps away from completing your U.S. federal tax forms in an easy and efficient way! Your Identification Number (if you have been assigned one); · U.S. Entry and Exit Dates for current and all pastWelcome to GLACIER Tax Prep We hope you find GLACIER Tax Prep simple to use and easy to understand

Mullins, Dyche

340

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

341

Observed Mass Balance of Mountain Glaciers and Greenland Ice Sheet in the 20th Century and the Present Trends  

Microsoft Academic Search

Glacier mass balance and secular changes in mountain glaciers and ice caps are evaluated from the annual net balance of 137\\u000a glaciers from 17 glacierized regions of the world. Further, the winter and summer balances for 35 glaciers in 11 glacierized\\u000a regions are analyzed. The global means are calculated by weighting glacier and regional surface areas. The area-weighted global\\u000a mean

Atsumu Ohmura

2011-01-01

342

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

E-print Network

-covered glaciers Frank Paul*, Christian Huggel, Andreas Ka¨a¨b Department of Geography, Glaciology glacier mapping from satellite multispectral image data is hampered by debris cover on glacier surfaces deposits, and bedrock outside the glacier margin, and is thus not detectable by means of multispectral

Kääb, Andreas

343

Response time of glaciers as a function of size and mass balance: 1. Theory  

Microsoft Academic Search

A simple interpretation of the traditional definitions of glacier and ice sheet response time (e.g., thickness divided by mass balance rate, h\\/b) suggests that larger glaciers respond more slowly than small glaciers to a perturbation in climate. However, with reasonable choices for mass balance behavior, a scaling analysis shows that the response time of valley glaciers decreases as a function

David B. Bahr; W. Tad Pfeffer; Christophe Sassolas; Mark F. Meier

1998-01-01

344

Geomorphological and sedimentological record of accelerated deglaciation of small mountain glacier, Ragnarbreen, Svalbard  

Microsoft Academic Search

Most of the Svalbrad glaciers have been in retreat since the end of the Little Ice Age (LIA). Hence, they give a good opportunity to study the geomorphological and sedimentological record of deglaciation. The aim of the study is to describe main landsystem elements of Ragnar glacier and relate them to different stages of the glacier recession. The Ragnar glacier

Marek Ewertowski

2010-01-01

345

Recommendations for the compilation of glacier inventory data from digital sources  

E-print Network

Recommendations for the compilation of glacier inventory data from digital sources F. PAUL,1 R techniques allow the automated creation of detailed glacier inventory data from glacier outlines and digital terrain models (DTMs). Once glacier entities are defined and an appropriate DTM is available, several

346

The application of remote sensing technology in the glacier change monitoring of Yulong Mountain  

Microsoft Academic Search

This study, based on remote sensing and GIS technologies, the glacier distribution map and related parameters in 1999 are obtained with some spatial data including remote sensing images, DEM, and so on. Compared to data in 1957, in 1999, there are only 15 glaciers in this area and 4 glaciers disappeared; the glacier area is 8.5, with the total reduction

Song Bo; Ye Baisheng; Han Tianding

2010-01-01

347

Controls on Surging in East Greenland Derived From a new Glacier Inventory  

Microsoft Academic Search

Glacier surging is often classified as a distinct type of bimodal flow behaviour. Yet, studies of surging show a spectrum in surge behaviour, where initiation and termination, as well velocity development and periodicity can vary greatly from glacier to glacier. It is clearly possible that different classes of surge behaviour involve different controls on glacier flow. Environmental and glacial characteristics

H. Jiskoot; A. Luckman; T. Murray

2001-01-01

348

Equilibrium-line altitudes on reconstructed LGM glaciers of the northwest Barguzinsky Ridge, Northern Baikal, Russia  

Microsoft Academic Search

The spatial extent of the Last Glacial Maximum (LGM) glaciers (MIS 2) in the northwest of the Barguzinsky Ridge has previously been mapped. Geographical information system (GIS)-computing of the glaciers' quantitative parameters allowed us to use various methods to evaluate the former equilibrium-line altitudes (ELAs) for the 10 largest glaciers. ELAs on reconstructed glaciers were calculated using four common methods:

Eduard Yu Osipov

2004-01-01

349

Remote sensing and GIS techniques for assessing decadal glacier changes in the Sikkim and Nepal Himalayas  

Microsoft Academic Search

There is urgency in developing and testing remote sensing tools for developing extensive glacier datasets in high altitude areas of the Himalayas. Detailed information about glacier parameters is missing in many areas of the Himalayas, limiting our understanding of glacier fluctuations in this area. One of the biggest challenges in glacier mapping from spaceborne imagery is the delineation of debris-covered

A. Racoviteanu

2009-01-01

350

Mapping glacier changes, snowline altitude and AAR using Landsat data in Svartisen, Northern Norway  

Microsoft Academic Search

Changes in glacier area and volume indicate changes in local climate. Water resources of glaciers are utilised e.g. by hydropower production and agriculture. However, laborious field measurements have been restricting monitoring efforts only to a small number of glaciers. In this study the glacier changes, snowline altitude and accumulation area ratio (AAR) were assessed in and around Svartisen icecaps in

J. Heiskanen; K. Kajuutti; P. Pellikka

2003-01-01

351

Climate downscaling for estimating glacier mass balances in northwestern North America: Validation with a USGS  

E-print Network

Climate downscaling for estimating glacier mass balances in northwestern North America: Validation] An atmosphere/glacier modeling system is described for estimating the mass balances of glaciers in both current to force a precipitation- temperature-area-altitude (PTAA) glacier mass balance model with daily maximum

Bhatt, Uma

352

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

353

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

354

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

USGS Publications Warehouse

Combined ice and water balances were measured in the 1967 hydrologic year (October 1-September 30) on four glaciers in western North America ranging in latitude from 37 deg to 63 deg N. This hydrologic year was characterized by heavier than normal winter precipitation in California and Washington and abnormally dry winter conditions in coastal Alaska. In summer the western conterminous states were abnormally dry and central and southern Alaska experienced very wet conditions. Maclure Glacier (lat 37 deg 45' N., 3,650-m (metres) mean equilibrium line altitude) had an above normal winter balance of 3.46 m and a positive annual balance of 1.05 m (metres of water equivalent). South Cascade Glacier (lat 48 deg 22' N., 1900-m mean equilibrium line altitude) had a winter balance of 3.28 m, slightly above average. Above normal summer ablation resulted in a final annual balance of -0.58 m, slightly more negative than has been the case for the past decade. Wolverine Glacier's (lat 60 deg 24' N., 1,200-m mean equilibrium line altitude) winter balance was 1.17 m, considerably below normal; the annual balance was -2.04 m. Gulkana Glacier (lat 63 deg 15' N., 1,700-m mean equilibrium line altitude) had a winter balance of 1.05 m, approximately normal for this glacier; the final annual balance was -0.30 m.

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

1977-01-01

355

Transport of heat and salt driven by remote shelf winds in a glacial fjord of East Greenland  

NASA Astrophysics Data System (ADS)

Greenland's glacial fjords form a key link in the climate system between the open ocean and the ice sheet's outlet glaciers. The circulation in these fjords controls heat transport to the glaciers and submarine melting, thereby potentially affecting glacier behavior and the mass balance of the Greenland Ice Sheet. Here, we use ocean data from Sermilik Fjord, where Helheim Glacier drains, to quantify the circulation and identify the leading order drivers. Using three years of moored velocity and CTD records and ERA Interim Reanalysis wind fields, we find evidence of a strong fjord response to remote winds on the shelf. Large along-shore winds events (called barrier winds in this region) drive isopycnal movements on the shelf and subsequent baroclinic flows within the fjord. Beyond an intense transient response throughout the length of the fjord, these flows can also trigger a marked shift in properties both in the outflowing glacial meltwater and the inflowing ocean water within the fjord. The interaction between the freshwater input from the glacier and the remote forcing from winds on the shelf is examined.

Jackson, R. H.; Straneo, F.; Sutherland, D. A.

2012-12-01

356

Glacier-like forms on Mars  

NASA Astrophysics Data System (ADS)

More than 1300 glacier-like forms (GLFs) are located in Mars' mid-latitudes. These GLFs are predominantly composed of ice-dust mixtures and are visually similar to terrestrial valley glaciers, showing signs of downhill viscous deformation and an expanded former extent. However, several fundamental aspects of their behavior 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 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 best-estimate mean GLF flow speed of 7.5 mm a-1; and (iv) GLF hydrology, focusing on supra-GLF gulley networks. On the basis of this information, we summarize the current state of knowledge of the glaciology of martian GLFs and identify future research avenues.

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

2014-11-01

357

Numerical Modeling of Glaciers in Martian Paleoclimates  

NASA Technical Reports Server (NTRS)

Numerous geologic features suggest the presence of ice flow on the surface of mars. These features include lobate debris aprons, concentric crater fill, and lineated valley fill. The lateral extent of these features can range from 100 meters to over 20 km. Previous work has demonstrated that these features could not have formed in current Martian conditions. It has long been speculated that changes in Mars orbital properties, namely its obliquity, eccentricity, and argument of perihelion, can result in dramatic changes to climate. Recent climate model studies have shown that at periods of increased obliquity north polar water ice is mobilized southward and deposited at low ad mid latitudes. Mid latitude accumulation of ice would provide the necessary conditions for rock glaciers to form. A time-marching, finite element glacier model is used to demonstrate the ability of ice and ice-rock mixtures to flow under Martian paleoclimate conditions. Input to this model is constrained by the NASA Ames Mars General Circulation Model (MGCM).

Colaprete, A.; Haberle, R. M.; Montmessin, F.; Scheaffer, J.

2004-01-01

358

A GIS and Remote Sensing Based Approach to Monitoring the Bering Glacier System  

Microsoft Academic Search

The Bering Glacier is the largest and longest glacier in continental North America, with an area of approximately 5,175 km2, and a length of 190 km. It is also the largest surging glacier in America, having surged at least five times during the twentieth century. The last surge of the Bering Glacier occurred in 1993-1995, since then, the glacier has

Sean Savage; Robert Shuchman; Edward G. Josberger; John Payne; Chris Noyles; Scott Guyer; Guy Meadows

359

A comparison of late glacial to early Holocene fluctuations of Greenland Ice Sheet outlet glaciers with nearby mountain glaciers in central east Greenland  

NASA Astrophysics Data System (ADS)

Recent rapid fluctuations of Greenland Ice Sheet outlet glaciers have alarmed scientists and the public alike. These outlet glacier fluctuations may result from the internal mechanics of tidewater glaciers or the influence of ocean-water temperatures on glacial melting. In contrast, it is generally assumed that fluctuations of temperate mountain glaciers are influenced mainly by summer temperatures and, to a lesser amount, winter precipitation. Here we show that during late glacial and early Holocene time Greenland Ice Sheet outlet glacier fluctuations occurred at the same time as mountain glacier fluctuations in central east Greenland. Our recent work in the Scoresby Sund region of central east Greenland used equilibrium line altitudes determined from past mountain glacier extents to estimate summer temperatures during late glacial and early Holocene time. A chronology of these past mountain glacier extents is based on surface exposure (10Be) dating of moraines and a radiocarbon-dated relative sea level curve. In this same area, we applied 10Be dating to determine a chronology of past extents of Greenland Ice Sheet outlet glaciers. We present thirty new 10Be ages of moraines deposited by outlet glaciers located adjacent to mountain glaciers in the Scoresby Sund region. A comparison of the outlet glacier moraine ages with the previously determined chronology of mountain glacier extents shows that, during late glacial and early Holocene time, Greenland Ice Sheet outlet glaciers and mountain glaciers fluctuated on similar time scales. These results suggest that the ice sheet margin was sensitive to local climatic conditions, most likely summer temperatures. If so, the magnitude of summer cooling that drove the mountain glacier advances, estimated at 3.6 to 6.6C, also influenced significant advances of outlet glaciers.

Kelly, M. A.; Lowell, T. V.; Hall, B. L.; Schaefer, J. M.

2010-12-01

360

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

361

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

362

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

363

Surge dynamics in the Nathorstbreen glacier system, Svalbard  

NASA Astrophysics Data System (ADS)

Nathorstbreen glacier system (NGS) recently experienced the largest surge in Svalbard since 1936, and this was examined using spatial and temporal observations from DEM differencing, time series of surface velocities from satellite synthetic aperture radar (SAR) and other sources. The upper basins with maximum accumulation during quiescence corresponded to regions of initial lowering. Initial speed-up exceeded quiescent velocities by a factor of several tens. This suggests that polythermal glacier surges are initiated in the temperate area before mass is displaced downglacier. Subsequent downglacier mass displacement coincided with areas where glacier velocity increased by a factor of 100-200 times (stage 2). After more than 5 years, the joint NGS terminus advanced abruptly into the fjord during winter, increasing velocities even more. The advance was followed by up-glacier propagation of crevasses, indicating the middle and subsequently the upper part of the glaciers reacting to the mass displacement. NGS advanced ~15 km, while another ~3 km length was lost due to calving. Surface lowering of ~50 m was observed in some up-glacier areas, and in 5 years the total glacier area increased by 20%. Maximum measured flow rates were at least 25 m d-1, 2500 times quiescent velocity, while average velocities were about 10 m d-1. The surges of Zawadzkibreen cycle with ca. 70-year periods.

Sund, M.; Lauknes, T. R.; Eiken, T.

2014-04-01

364

Summer energy balance and ablation of high elevation glaciers in the central Chilean Andes  

NASA Astrophysics Data System (ADS)

Glaciers of the semi-arid central Chilean Andes are an important freshwater source for the populous Central Valley region of Chile, but have been shrinking in recent decades. The surface energy balance of these glaciers is of high scientific interest as summer ablation occurs through both sublimation and melt. During the 2012-13 Austral Summer a glacio-meteorological monitoring programme was established on Olivares Alfa (3.9 km2, 4130-4800 m elevation) and Beta (8.3 km2, 3620-4850 m elevation) Glaciers and their forelands in the Upper Olivares Valley, 3300'-3311' S, 7005'-7015' W, approximately 50 km north-east of Santiago. This included complete automatic weather stations (AWSs) with sonic rangers to record surface ablation on the ablation zones of the two glaciers, and one AWS in the proglacial area of Olivares Alfa Glacier including precipitation gauge. To complement these point data, daily images of the glaciers were captured with fixed cameras in order to calculate snow cover and albedo distributions. To calculate the surface energy balance and rates of melt and sublimation, a model was developed which uses direct AWS measurements of the radiative fluxes and calculates the turbulent fluxes of sensible and latent heat using the bulk aerodynamic approach. The model also calculates the subsurface heat flux and includes a simple scheme to estimate refreezing of melt water within surface snow or ice. Meteorological data and model results for the December to May period will be presented in this paper. Model calculations match closely the cumulative ablation curve of the sonic ranger at Olivares Alfa, with a slight overestimation, and overestimate cumulative ablation recorded by the sonic ranger at Olivares Beta, possibly due, at least in part, to uncertain snow density values. Modelled cumulative ablation in the December-April period is 2.2 m water equivalent (w.e.) at Olivares Alfa (0.10 m sublimation, 2.10 m melt) and 2.34 m w.e. at Olivares Beta (0.18 m sublimation, 2.16 m melt). The surface energy balance is dominated by shortwave radiation, which is the only net energy input, apart from a minor contribution from sensible heat, while the main outputs of energy are net longwave radiation, melt and sublimation. Ablation is dominated by melt during the warmer midsummer months at the two AWS sites, with mean rates exceeding 30 mm w.e. per day. However, due to the high latent heat of sublimation, it is only in January and February that the melt energy flux clearly exceeds the sublimation energy flux. Sublimation rates are typically ~1 mm w.e. per day and are 50 to 100 % higher at Olivares Beta as a result of higher wind speed and surface temperature, despite similar air temperatures at the two sites. Melt rates are around twice as high in summer months with mean air temperature > -2 C, compared with cooler months. This implies that future atmospheric warming will accelerate shrinkage of these glaciers as the ablation regime switches increasingly from sublimation to a more efficient melt regime.

Brock, Benjamin; Rivera, Andres; Burger, Flavia; Bravo, Claudio

2014-05-01

365

New glacier inventory of Salzburg 2007/09  

NASA Astrophysics Data System (ADS)

Glacier inventories are an important data basis for several investigations such as length-, area- and volume changes in the course of climate change. The new glacier inventory of Salzburg is part of the third Austrian glacier inventory (GI3) and is valid for the years 2007 and 2009 depending on each mountain range. The first inventory (GI1) was compiled in 1969 and the second one (GI2) represents the glacier state from 1998 to 2002. In Salzburg, 150 glaciers are located in the six mountain ranges: Ankogel, Glockner, Granatspitz, Sonnblick (Goldberg), Hochknig and Venediger. The basis for the new mapping were orthophotos of 2007 and 2009 and the DEM of the southern part of Salzburg. On the basis of former inventories area-, height- and volume changes have been calculated. The biggest loss of glacier area per mountain range was found in the Ankogel range and on Hochknig because of the disrupted structure of the thin glaciers. Referring to the absolute values, the largest changes took place in the Glockner- and Venediger mountain range with -10.11 km2 and -9.72 km2 during the period between GI1 (1969) and GI3 (2007/2009) respectively. Due to the lack of DEMs (only the southern part was available) volume changes have been calculated for about half of all glaciers in Salzburg. These are located at the Glockner, Granatspitz and Sonnblick mountain range and showed -0.335 km3 on average changes in height of 9.3 m. An extrapolation of these changes to all of the 150 glaciers in Salzburg results in a loss of about 0.7 km3 between GI1 and GI3.

Stocker-Waldhuber, M.; Wiesenegger, H.; Fischer, A.

2012-04-01

366

WIND ENERGY Wind Energ. (2014)  

E-print Network

the turbulent atmosphere and the wind turbine wake in order to optimize the design of the wind turbine as well.com). DOI: 10.1002/we.1792 RESEARCH ARTICLE Self-similarity and turbulence characteristics of wind turbine by a single wind turbine are studied in this paper with a new large eddy simulation (LES) code, the wind

367

Comparing In Situ Spectra and Multispectral Classifications of Glacier Surfaces  

NASA Astrophysics Data System (ADS)

Glaciers can be divided into distinct surface zones (or facies) such as new snow, firn, slush, and glacier ice, which can then be quantitatively linked to the mass balance state of a glacier. Due to similarities in reflective properties, persistent difficulty is had identifying the snow line and accumulation area rather than the more distinct glacier ice-firn line. Yet, it is the snow line rather than the firn line which provides a sensitive indicator of how a given year's climate influences a glacier. As small icecaps and glaciers contribute significantly to current sea level rise and will continue to do so in the coming decades, it would be highly beneficial to develop a technique which measures a glacier mass balance proxy - the glacier accumulation area ratio - using widespread, high resolution multispectral imagery. In situ glacier surface spectra (350-2300 nm) were measured on Midtre Lovnbreen (Svalbard) in August 2010 and Langjkull (Iceland) in August 2011 using an ASD field spectroradiometer. The full-spectrum reflectance measurements allow simulation of various airborne and spaceborne multispectral sensors including the Airborne Thematic Mapper, Landsat ETM+, MODIS or MERIS, and ESA's forthcoming Sentinel 2. Published studies have applied methods such as spectral band ratios, normalized indices, thresholding, principal component analysis, unsupervised classification, supervised classification, and spectral mixing analysis to classify glacier surfaces. The work presented here uses the collected in situ surface reflectance data to inform interpretation of ISODATA classification schemes of airborne and satellite multispectral imagery, can provide end member points for spectral mixing studies, and gives a starting point from which to further develop useful analysis strategies for remote imagery. Future research directions could integrate elevation and intensity data from airborne LiDAR campaigns. While spectra and classifications of airborne/satellite multispectral imagery match reasonably for Svalbard data, this is not the case between in situ measurements from Svalbard and imagery from Iceland. This paper will investigate not only the potential causes of differing spectral properties of glacier surfaces in Svalbard and Iceland, but also use the in situ spectra to evaluate classification techniques and inform more effective and reliable strategies for remotely measuring a glacier's accumulation area.

Pope, A.; Rees, G.; Willis, I. C.; Arnold, N. S.

2011-12-01

368

Ocean-Glacier Interactions in Alaska and Comparison to Greenland  

NASA Astrophysics Data System (ADS)

Meltwater from Alaska's coastal glaciers and icefields accounts for nearly half of the total freshwater discharged into the Gulf of Alaska (GOA), with 10% coming from glacier volume loss associated with rapid thinning and retreat of glaciers (Neal et al, 2010). This glacier freshwater discharge contributes to maintaining the Alaska Coastal Current (ACC), which eventually reaches the Arctic Ocean (Royer and Grosch, 2006), thereby linking changes of glaciers along the coast of Alaska to the whole Arctic system. Water column temperatures on the shelf of northern GOA, monitored at buoy GAK1 near Seward, have increased by about 1 deg C since 1970 throughout the 250 m depth and vertical density stratification has also increased. Roughly half of the glacier contribution to ACC is derived from the ~ 50 tidewater glaciers (TWG) that drain from Alaska's coastal mountains into the Gulf of Alaska (GOA). Fjord systems link these TWGs to the GOA, with fjord circulation patterns driven in part by buoyancy-driven convection of subglacial freshwater discharge at the head of the fjord. Neoglacial shallow sills (< 50 m deep) modulate the influx of warm ocean waters (up to 10 deg C) into these fjords. Convection of these warm waters melts icebergs and submerged faces of TWGs. The study of interactions between glaciers, fjords, and the ocean in coastal Alaska has had a long but very sporadic history. We examine this record starting with the "TWG cycle" hypothesis. We next examine recent hydrographic data from several different TWG fjords, representative of advancing and retreating TWGs (Columbia, Yahtse, Hubbard, and LeConte Glaciers), evaluate similarities and differences, and estimate the relative contributions of submarine glacier melting and subglacial discharge to fjord circulation. Circulation of warm ocean waters in fjords has also been hypothesized to play an important role in destabilizing and modulating glacier discharge from outlet glaciers in Greenland. We therefore compare hydrographic data from Alaskan fjords to Greenland data and evaluate similarities and differences. Studies on Alaskan fjords have implications for understanding land ice - ocean interactions in Greenland as well as elsewhere in the world but much more needs to be learned on how these fjords operate.

Motyka, R. J.; Truffer, M.

2011-12-01

369

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

370

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

371

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

372

Glaciers along the Copper River, Alaska, Controlled by Landslides, Vegetation, Lakes, Rivers (and Climate)  

NASA Astrophysics Data System (ADS)

98% of glaciers in Alaska are retreating or thinning at low elevations due to warming; some are thickening at high elevations due to rising precipitation. Anomalous surge and tidewater glaciers are much studied. Debris-covered, freshwater-calving glaciers and juxtaposed land-terminating glaciers have their own peculiar dynamics, as exemplified by glaciers in the Copper River corridor, Alaska. Those glaciers are losing area and mass, consistent with Alaska's general trend and recent climate change. Other factors can exceed or negate climatic influences on individual glaciers or parts of glaciers. For example, the terminus of Childs Glacier has been almost stable for a century due to thermal/mechanical buffering by undercutting and calving in the Copper River. Thick debris insulates glacier ice and retards glacier thinning and retreat. This protective effect is enhanced when vegetation becomes established on glacier debris cover and cools the glacier's surface. However, debris and vegetation also impedes drainage and can cause runaway lake growth. Further complexity is caused by unsteady inputs of landslide debris, size-dependent glacier response times, and influences of ice-contact lakes on glacier energy balance. Landslides can load and accelerate glaciers in the first years afterward, and on century time scales thick debris insulates and promotes vegetation growth, which first tends to stabilize glaciers, but the debris and vegetation eventually induce supraglacial ponding, lake growth and glacier disintegration. Allen Glacier exhibits composite effects of (1) calving into the Copper River at the peak of the Little Ice Age, (2) slow response to the termination of the Little Ice Age; (3) landslides, debris insulation, and vegetational cooling; (4) nonlinear lake growth; and (5) decades of warming climate, renewed melting, and disarticulation.

Kargel, J. S.; Furfaro, R.; Banks, M.; Fischer, L.; Hoelzle, M.; Huggel, C.; Leonard, G.; Molnia, B.; Roer, I.; Wessels, R.; Wolfe, D.; Bianchi, L.

2008-12-01

373

Monitoring glacier and supra-glacier lakes from space in Mt. Qomolangma region of the Himalayas on the Tibetan Plateau in China  

Microsoft Academic Search

Because of the large number and remoteness, satellite data, including microwave data and optical imagery, have commonly been\\u000a used in alpine glaciers surveys. Using remote sensing and Geographical Information System (GIS) techniques, the paper presents\\u000a the results of a multitemporal satellite glacier extent mapping and glacier changes by glacier sizes in the Mt. Qomolangma\\u000a region at the northern slopes of

Qinghua Ye; Zhenwei Zhong; Shichang Kang; Alfred Stein; Qiufang Wei; Jingshi Liu

2009-01-01

374

Repeated Rapid Retreats of Bering Glacier by Disarticulation - The Cyclic Dynamic Response of an Alaskan Glacier System  

NASA Astrophysics Data System (ADS)

Bering Glacier is the largest glacier in continental North America, with an area greater than 5,000 square kilometers. Alone, it accounts for more than 6% of the glacier-covered area of Alaska and perhaps 15% of Alaska's glacier ice. In places, its bed is more than 250 m below sea level. It is also the largest surging temperate glacier on Earth. Surges, some with maximum ice displacements exceeding 13 km, occurred at least five times during the 20th century. Analysis of aerial photography, dating from 1936, and satellite imagery, dating from 1972, documents that following each of the last four surges, Bering Glacier experienced post-surge, decadal-scale, cyclic episodes of rapid retreat. In each instance, the primary mechanism responsible for the rapid retreat was a buoyancy-driven process, here named `disarticulation.' Abundant imagery exists to carefully document the post-surge retreat pattern during the two most recent cycles, 1967-1992 and 1996-present. In each cycle retreat began by calving. However, within a few years, as the piedmont lobe rapidly thinned, often by more than 20 m/yr, the dominant process transitioned to disarticulation, and the rate of retreat greatly increased. Disarticulation events occur when the thinning, low-gradient, distal end of the glacier's piedmont lobe reaches a state of buoyancy and separates from its bed. As it begins to float, large tabular pieces of ice up to a kilometer in maximum dimension passively separate from the terminus. Separation usually occurs along old crevasse and fracture planes and may begin at distances of more than 2 km behind the terminus. Often, hundreds of large icebergs simultaneously separate. Disarticulation events were also identified as being underway on photographs from 1936 and 1948. These followed surge that ended in the 1920s and 1940. In both 1936 and 1948, disarticulation was occurring at the same location. This location was also a focal point for disarticulation during the last two post-surge cycles. The post-1967 surge cycle spanned 25 years and resulted in a maximum of 10.7 km of terminus recession. Maximum annual recession exceeded 2.5 km. In the post-1996 cycle, maximum retreat is more than 6 km. Disarticulation is not unique to Bering Glacier, and probably not unique to Alaska. A 2005 aerial survey of Alaskan coastal glaciers identified more than a dozen glaciers, many former tidewater and calving glaciers, including Grand Plateau, Alsek, Bear, and Excelsior Glaciers that were rapidly retreating through disarticulation.

Molnia, B. F.

2005-12-01

375

Bathymetry of Patagonia glacier fjords and glacier ice thickness from high-resolution airborne gravity combined with other data  

NASA Astrophysics Data System (ADS)

The North and South Patagonia Ice fields are the largest ice masses outside Antarctica in the Southern Hemisphere. During the period 1995-2000, these glaciers lost ice at a rate equivalent to a sea level rise of 0.105 0.001 mm/yr. In more recent years, the glaciers have been thinning more quickly than can be explained by warmer air temperatures and decreased precipitation. A possible cause is an increase in flow speed due to enhanced ablation of the submerged glacier fronts. To understand the dynamics of these glaciers and how they change with time, it is critical to have a detailed view of their ice thickness, the depth of the glacier bed below sea or lake level, how far inland these glaciers remain below sea or lake level, and whether bumps or hollows in the bed may slow down or accelerate their retreat. A grid of free-air gravity data over the Patagonia Glaciers was collected in May 2012 and October 2012, funded by the Gordon and Betty Moore Foundation (GBMF) to measure ice thickness and sea floor bathymetry. This survey combines the Sander Geophysics Limited (SGL) AIRGrav system, SGL laser altimetry and Chilean CECS/UCI ANDREA-2 radar. To obtain high-resolution and high-precision gravity data, the helicopter operates at 50 knots (25.7 m/s) with a grid spacing of 400m and collects gravity data at sub mGal level (1 Gal =1 Galileo = 1 cm/s2) near glacier fronts. We use data from the May 2012 survey to derive preliminarily high-resolution, high-precision thickness estimates and bathymetry maps of Jorge Montt Glacier and San Rafael Glacier. Boat bathymetry data is used to optimize the inversion of gravity over water and radar-derived thickness over glacier ice. The bathymetry maps will provide a breakthrough in our knowledge of the ice fields and enable a new era of glacier modeling and understanding that is not possible at present because ice thickness is not known.

An, L.; Rignot, E.; Rivera, A.; Bunetta, M.

2012-12-01

376

Fast-flowing outlet glaciers on Svalbard ice caps  

SciTech Connect

Four well-defined outlet glaciers are present on the 2510 km{sup 2} cap of Vestfonna in Nordaustlandet, Svalbard. Airborne radio echo sounding and aerial-photograph and satellite-image analysis methods are used to analyze the morphology and dynamics of the ice cap and its component outlet glaciers. The heavily crevassed outlets form linear depressions in the ice-cap surface and flow an order of magnitude faster than the ridges of uncrevassed ice between them. Ice flow on the ridges is accounted for by internal deformation alone, whereas rates of outlet glacier flow require basal motion. One outlet has recently switched into and out of a faster mode of flow. Rapid terminal advance, a change from longitudinal compression to tension, and thinning in the upper basin indicate surge behavior. Observed outlet glacier discharge is significantly greater than current inputs of mass of the ice cap, indicating that present rates of flow cannot be sustained under the contemporary climate.

Dowdeswell, J.A. (Univ. of Cambridge (England)); Collin, R.L. (University College of Wales, Aberystwyth (England))

1990-08-01

377

Contribution of small glaciers to global sea level  

USGS Publications Warehouse

Observed long-term changes in glacier volume and hydrometeorological mass balance models yield data on the transfer of water from glaciers, excluding those in Greenland and Antarctica, to the oceans, The average observed volume change for the period 1900 to 1961 is scaled to a global average by use of the seasonal amplitude of the mass balance. These data are used to calibrate the models to estimate the changing contribution of glaciers to sea level for the period 1884 to 1975. Although the error band is large, these glaciers appear to accountfor a third to half of observed rise in sea level, approximately that fraction not explained by thermal expansion of the ocean.

Meier, M.F.

1984-01-01

378

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

379

Hydrology of a land-terminating Greenlandic outlet glacier  

E-print Network

Hydrology is recognised as an important component of the glacial system in alpine environments. In particular, the subglacial drainage of surface meltwaters is known to exert a strong influence on the motion of glaciers ...

Cowton, Thomas Ralph

2013-11-28

380

JIRP Survey Report -2004 Foundation for Glacier and Environmental Research  

E-print Network

Report - 2004 CONTENS 1. Summary 5 2. Introduction 5 3. Survey Projects 12 3.1 Lemon Creek Glacier in elevation and flow velocities as well as determining pressure and deformation. In addition to the Lemon

381

Geology Fieldnotes: Glacier Bay National Park and Preserve, Alaska  

NSDL National Science Digital Library

This park is home to the Fairweather Mountains, which formed during the Laramide Orogeny, as well as many glaciers. The site includes introductory information about glacial formation and icebergs, links to park maps, and visitor information.

382

Native Westslope Cutthroat Trout in Glacier National Park  

USGS Multimedia Gallery

USGS Research Ecologist Clint Muhlfeld holdsa native westslope cutthroat trout in Glacier National Park. GNP is recognized as a range-wide stronghold for genetically pure westslope cutthroat trout. However, rainbow trout invasion and hybridization threatens these populations. ...

383

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

384

Neoglacial fluctuations of Deming Glacier, Mt. Baker, Washington USA.  

NASA Astrophysics Data System (ADS)

Deming Glacier flows from the upper west slopes of Mt. Baker, a stratovolcano in the Cascade Range of Washington, USA. The north and south lateral moraines of Deming Glacier are composed of at least four tills separated by layers of detrital wood and sheared stumps in growth position. The stratigraphy records fluctuations of the glacier during the Holocene. The outer ten rings of an in situ stump from the middle wood layer, which is about 40 m below the north lateral moraine crest and 1.2 km downvalley from the present glacier terminus, yielded an age of 1750 50~~ 14C yr BP [1810-1550 cal yr BP]. The stump revealed at least 300 rings and thus records a period of landscape stability and relatively restricted glaciation for several hundred years prior to ca. 1750 14C yr BP . Samples from the lowest wood layer also have been submitted for radiocarbon dating. Outer rings of detrital wood samples collected from two wood mats exposed in the south lateral moraine, 2.3 km downvalley of the glacier terminus, returned radiocarbon ages of 1600 30~~ 14C yr BP [1550- 1410 cal yr BP] and 430 30~~ 14C yr BP [AD 1420-1620]. These data indicate that Deming Glacier advanced over a vegetated moraine sometime after 1810 cal yr BP to a position less extensive that it achieved at the peak of the Little Ice Age. The glacier then receded before it began its final and most extensive Holocene advance after AD 1420. The older advance is correlative with the 'First Millennium AD' advance, recently recognized throughout western North America. The younger advance coincides with an advance of Mt. Baker's Easton Glacier [AD 1430-1630], and advances of many alpine glaciers elsewhere in western North America. Our data suggest that glaciers on Mt. Baker fluctuated in a similar manner to alpine glaciers in the Coast Mountains of British Columbia and in other mountain ranges of northwest North America during Neoglaciation.

Osborn, G.; Menounos, B.; Scott, K.; Clague, J. J.; Tucker, D.; Riedel, J.; Davis, P.

2007-12-01

385

Characteristics of the turbulent flow in the boundary layer of a Tropical Glacier  

NASA Astrophysics Data System (ADS)

An extensive micro-meteorological experiment has been deployed within the atmospheric boundary layer over the ablation zone of the tropical Zongo glacier, Bolivia, during the dry season from July to August, 2007. It included two complete eddy correlation systems (Campbell CSAT and LICOR7500) at a 2-m mean level and a 6-m mast measuring the mean profiles of air temperature (type-T artificially ventilated thermocouples) and of wind speed (Vector A100R). Weakly stable conditions prevailed in the first meters above the ice or snow surface. With weak large scale forcing, a katabatic downslope flow with a wind maximum at about 2-m height usually appeared in the middle of the afternoon and maintained itself during most of the night. Characteristics and structure of the turbulent flow were studied using spectral and quadrant analysis, along with the study of statistical moments of high frequency wind speed and temperature data. The wind regime was found to be highly gusty and irregular: more than 50% of the flux was exchanged during less than 10% of the time. Stationary conditions were rarely encountered. The spectral analysis shows that the observed turbulence cannot be generated only by local shear, and that some outside layer perturbations must transport kinetic energy in the vicinity of the surface. Flux exchanges are thus found to be greater than predicted by aerodynamic approaches which use mean temperature and wind speed measurements and stability-correction functions based on the Monin-Obukhov similarity theory. The net surface energy balance is quantified during selected periods using fusion measurements derived from height variations of the ice surface (measured with an ultrasonic depth gauge). It is compared to the energy balance computed from radiative balance along with mean wind speed and temperature or eddy covariance fluxes.This data helps us to quantify errors made with classical similarity methods, and their variation regarding to meteorological forcings.

Litt, M.; Sicart, J.

2012-12-01

386

Brief Communication "The 2013 Erebus Glacier Tongue calving event"  

NASA Astrophysics Data System (ADS)

The Erebus Glacier Tongue, a small floating glacier in southern McMurdo Sound, is one of the best-studied ice tongues in Antarctica. Despite this, its calving on the 27 February 2013 (UTC) was around 10 yr earlier than previously predicted. The calving was likely a result of ocean currents and the absence of fast ice. The subsequent trajectory of the newly created iceberg supports previous descriptions of the surface ocean circulation in southern McMurdo Sound.

Stevens, C. L.; Sirguey, P.; Leonard, G. H.; Haskell, T. G.

2013-09-01

387

Eukaryotic microorganisms in cold environments: examples from Pyrenean glaciers  

PubMed Central

Little is known about the viability of eukaryotic microorganisms preserved in icy regions. Here we report on the diversity of microbial eukaryotes in ice samples derived from four Pyrenean glaciers. The species composition of eukaryotic communities in these glaciers is unknown mostly because of the presence of a multi-year ice cap, and it is not clear whether they harbor the same populations. The recent deglaciation of these areas is allowing an easy access to glacial layers that correspond to the Little Ice Age although some isolated deposits are attributed to previous glacial cycles. In this study, we use molecular 18S rRNA-based approaches to characterize some of the microbial eukaryotic populations associated with Pyrenean glaciers. Firstly, we performed a chemical and microscopical characterization of ice samples. Secondly, molecular analyses revealed interesting protist genetic diversity in glaciers. In order to understand the microbial composition of the ice samples the eukaryotic communities resident in the glacial samples were examined by amplifying community DNA and constructing clone libraries with 18S rRNA primers. After removal of potential chimeric sequences and dereplication of identical sequences, phylogenetic analysis demonstrated that several different protists could be identified. Protist diversity was more phylum rich in Aneto and Monte Perdido glaciers. The dominant taxonomic groups across all samples (>1% of all sequences) were Viridiplantae and Rhizaria. Significant variations in relative abundances of protist phyla between higher and lower glaciers were observed. At the genus level, significant differences were also recorded for the dominant genera Chloromonas, Raphidonema, Heteromita, Koliella, and Bodomorpha. In addition, protist community structure showed significant differences between glaciers. The relative abundances of protist groups at different taxonomic levels correlated with the altitude and area of glaciers and with pH of ice, but little or no relationships to other chemical characteristics were found. PMID:23515855

Garca-Descalzo, Laura; Garca-Lpez, Eva; Postigo, Marina; Baquero, Fernando; Alcazar, Alberto; Cid, Cristina

2013-01-01

388

Acceleration in thinning rate on western Svalbard glaciers  

Microsoft Academic Search

Geodetic measurements indicate that a number of glaciers in western Svalbard ranging in size from 51000 km2 are losing mass at an accelerating rate. The average thinning rate for Midtre Lovnbreen, the glacier with the best data coverage, has increased steadily since 1936. Thinning rates for 20032005 are more than 4 times the average for the first measurement period 19361962

J. Kohler; T. D. James; T. Murray; C. Nuth; O. Brandt; N. E. Barrand; H. F. Aas; A. Luckman

2007-01-01

389

Acceleration in thinning rate on western Svalbard glaciers  

Microsoft Academic Search

Geodetic measurements indicate that a number of glaciers in western Svalbard ranging in size from 5-1000 km2 are losing mass at an accelerating rate. The average thinning rate for Midtre Lovnbreen, the glacier with the best data coverage, has increased steadily since 1936. Thinning rates for 2003-2005 are more than 4 times the average for the first measurement period 1936-1962

J. Kohler; T. D. James; T. Murray; C. Nuth; O. Brandt; N. E. Barrand; H. F. Aas; A. Luckman

2007-01-01

390

Slow surge of Trapridge Glacier, Yukon Territory, Canada  

Microsoft Academic Search

Trapridge Glacier, a polythermal surge-type glacier located in the St. Elias Mountains, Yukon Territory, Canada, passed through a complete surge cycle between 1951 and 2005. Air photos (19511981) and ground-based optical surveys (19692005) are used to quantify the modifications in flow and geometry that occurred over this period. Yearly averaged flow records suggest that the active phase began ?1980, and

Tom-Pierre Frapp; Garry K. C. Clarke

2007-01-01

391

Slow surge of Trapridge Glacier, Yukon Territory, Canada  

Microsoft Academic Search

Trapridge Glacier, a polythermal surge-type glacier located in the St. Elias Mountains, Yukon Territory, Canada, passed through a complete surge cycle between 1951 and 2005. Air photos (1951-1981) and ground-based optical surveys (1969-2005) are used to quantify the modifications in flow and geometry that occurred over this period. Yearly averaged flow records suggest that the active phase began ~1980, and

Tom-Pierre Frapp; Garry K. C. Clarke

2007-01-01

392

Modelling the response of glaciers to climate warming  

Microsoft Academic Search

Dynamic ice-flow models for 12 glaciers and ice caps have been forced with various climate change scenarios. The volume of\\u000a this sample spans three orders of magnitude. Six climate scenarios were considered: from 1990 onwards linear warming rates\\u000a of 0.01, 0.02 and 0.04?K a-1, with and without concurrent changes in precipitation. The models, calibrated against the historic record of glacier

J. Oerlemans; B. Anderson; A. Hubbard; P. Huybrechts; T. Jhannesson; W. H. Knap; M. J. Schmeits; A. P. Stroeven; J. Wallinga; Z. Zuo

1998-01-01

393

Asynchronous maximum advances of mountain and continental glaciers  

Microsoft Academic Search

The last maximum glacier advance in many mountain ranges appears to have predated the last maximum advance of the Wisconsinan continental ice sheets (~20,000 years B.P.). Published evidence from widely spaced localities in North and South America, Europe, Asia, and Hawaii suggests that some mountain glaciers extended farther during one or more stades early in the last glaciation, roughly 115,000-30,000

Alan Gillespie; Peter Molnar

1995-01-01

394

Glacier responses to recent volcanic activity in Southern Chile  

Microsoft Academic Search

Glaciers in Southern Chile (3943S) are characterized by frontal retreats and area losses in response to the ongoing climatic changes at a timescale of decades. Superimposed on these longer-term trends, volcanic activity is thought to impact glaciers in variable ways. Debrisash covered Glaciar Pichillancahue-Turbio only retreated slightly in recent decades in spite of been located on Volcn Villarrica which has

Andrs Rivera; Francisca Bown; Daniela Carrin; Pablo Zenteno

2012-01-01

395

Mass balance investigation of alpine glaciers through LANDSAT TM data  

NASA Technical Reports Server (NTRS)

An analysis of LANDSAT Thematic Mapper (TM) data of the Pasterze Glacier and the Kleines Fleisskees in the Austrian Alps was undertaken and compared with meteorological data of nearby weather stations. Alpine or valley glaciers can be used to study regional and worldwide climate changes. Alpine glaciers respond relatively fast to a warming or cooling trend in temperature through an advance or a retreat of the terminus. In addition, the mass balance of the glacier is being affected. Last year two TM scenes of the Pasterze Glacier of Aug. 1984 and Aug. 1986 were used to study the difference in reflectance. This year, in addition to the scenes from last year, one MSS scene of Aug. 1976 and a TM scene from 1988 were examined for both the Pasterze Glacier and the Kleines Fleisskees. During the overpass of the LANDSAT on 6 Aug. 1988 ground truthing on the Pasterze Glacier was undertaken. The results indicate that there was considerable more reflectance in 1976 and 1984 than in 1986 and 1988. The climatological data of the weather stations Sonnblick and Rudolfshuette were examined and compared with the results found through the LANDSAT data. There were relations between the meteorological and LANDSAT data: the average temperature over the last 100 years showed an increase of .4 C, the snowfall was declining during the same time period but the overall precipitation did not reveal any significant change over the same period. With the use of an interactive image analysis computer, the LANDSAT scenes were studied. The terminus of the Pasterze Glacier retreated 348 m and the terminus of the Kleines Fleisskees 121 m since 1965. This approach using LANDSAT MSS and TM digital data in conjunction with meteorological data can be effectively used to monitor regional and worldwide climate changes.

Bayr, Klaus J.

1989-01-01

396

GLACIER DAMMED LAKES AND OUTBURST FLOODS IN ALASKA  

Microsoft Academic Search

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

Austin Post; Lawrence R. Mayo; ATLAS HA

1971-01-01

397

Velocity change and ice discharge from Antarctic Peninsula Glaciers  

NASA Astrophysics Data System (ADS)

Satellite radar interferometry data from ERS-1/2 acquired in 1996 were employed to map the ice velocity of the outlet glaciers discharging ice along the eastern flank of the Peninsula from 64 south to 71 south, and along the former Wordie Ice Shelf in the west. Differential radar interferometry was employed to map the position of the glacier grounding lines. Estimates of ice thickness at the grounding line were obtained from hydrostatic equilibrium using existing topographic maps, or from direct measurement from radio echo sounding by BAS in 1994-2000 and CECS/NASA in 2002. The resulting glacier fluxes were compared to snow accumulation compiled by Turner et al. (2002) to deduce first-order estimates of the glacier mass balance. In places where ice shelves are known to have been retreating, we compared the 1996 velocities with older measurements as well as more recent estimates from ERS-1/2 (2000), Radarsat (2000-2003) and Aster (2002). On Fleming Glacier, we find a large increase in flow speed from 1972 to 1996, with no further increase after 1996, which suggests that the glacier did respond to the collapse of Wordie Ice Shelf several decades ago. On Drygakski glacier in the east, we confirm a large acceleration of the glacier following the collapse of Larsen B, as revealed by Rott et al. (2002), which is continuing to this date. We conclude on the effect of retreating ice shelves on the evolution of inland ice in this sector of Antarctica and on its impact on sea level rise.

Rignot, E.; Pritchard, H.; Vaughan, D.; Rivera, A.; Kanagaratnam, P.; Casassa, G.; Thomas, R.

2003-12-01

398

Glacier monitoring from Landsat TM: problems and perspectives  

Microsoft Academic Search

Thresholded ratio images from Landsat TM4 \\/ TM5 provide a simple, robust and quite accurate method for classification of clean glacier ice. Automatic retrieval of glacier inventory data is possible by means of GIS-based processing in combination with a DEM of appropriate accuracy. In view of the USGS-led project `Global Land Ice Monitoring from Space' (GLIMS) which aims at a

F. Paul; A. Kaeaeb; M. Maisch; M. Hoelzle; W. Haeberli

2003-01-01

399

Solar Radiation Patterns and Glaciers in the Western Himalaya  

NASA Astrophysics Data System (ADS)

Glacier dynamics in the Himalaya are poorly understood, in part due to variations in topography and climate. It is well known that solar radiation is the dominant surface-energy component governing ablation, although the spatio-temporal patterns of surface irradiance have not been thoroughly investigated given modeling limitations and topographic variations including altitude, relief, and topographic shielding. Glaciation and topographic conditions may greatly influence supraglacial characteristics and glacial dynamics. Consequently, our research objectives were to develop a GIS-based solar radiation model that accounts for Earth's orbital, spectral, atmospheric and topographic dependencies, in order to examine the spatio-temporal surface irradiance patterns on glaciers in the western Himalaya. We specifically compared irradiance patterns to supraglacial characteristics and ice-flow velocity fields. Shuttle Radar Mapping Mission (SRTM) 90 m data were used to compute geomorphometric parameters that were input into the solar radiation model. Simulations results for 2013 were produced for the summer ablation season. Direct irradiance, diffuse-skylight, and total irradiance variations were compared and related to glacier altitude profiles of ice velocity and land-surface topographic parameters. Velocity and surface information were derived from analyses of ASTER satellite data. Results indicate that the direct irradiance significantly varies across the surface of glaciers given local topography and meso-scale relief conditions. Furthermore, the magnitude of the diffuse-skylight irradiance varies with altitude and as a result, glaciers in different topographic settings receive different amounts of surface irradiance. Spatio-temporal irradiance patterns appear to be related to glacier surface conditions including supraglacial lakes, and are spatially coincident with ice-flow velocity conditions on some glaciers. Collectively, our results demonstrate that glacier sensitivity to climate change is also locally controlled by numerous multi-scale topographic parameters.

Dobreva, I. D.; Bishop, M. P.

2013-12-01

400

Glaciers, Climate and Society: Online Resources and Bibliography  

NSDL National Science Digital Library

Glaciers, Climate, and Society is designed to be a central location where students, teachers, parents, and researchers can begin their search for information and resources regarding glacier hazards, climate, water, and the human dimensions of these issues. Featuring many photos and embedded videos, the site provides K-12 education resources, issue summaries, information on Professor Mark Carey's research in the Andes, a resources and links page, and much more.

Mark Carey

401

Elevation change (2000-2004) on the Malaspina Glacier, Alaska  

NASA Technical Reports Server (NTRS)

The glaciers of the southeastern Alaska coastal region are the largest temperate glacier meltwater source on Earth and may contribute one third of the total glacier meltwater entering the global ocean. Since melt onset and refreeeze timing in this region show a tendency toward earlier onset and longer ablation seasons, accelerated glacier wastage may be occurring. In this study we focus on one of the largest temperate glacier systems on Earth, the Malaspina Glacier. This glacier, with a length of approximately 110 km and an area of approximately square 5,000 km, has the largest piedmont lobe of any temperate glacier. The entire lobe, which lies at elevations below 600 m, is within the ablation zone. We report and interpret ice elevation change between a digital elevation model (DEM) derived from the Shuttle Radar Topography Mission (SRTM C band) observations in Feb. 2000 and ICESat Laser 1-3 observations between Feb. 2003 and Nov. 2004. We use these elevation change results, along with earlier studies, to address the spatial and temporal variability in wastage of the piedmont lobe. Between 2000 and 2004 ice elevation changes of 10-30 meters occurred across the central Malaspina piedmont lobe. From 1972/73 (USGS DEM) to 1999 (SRTM corrected for estimated winter snow accumulation) Malaspina's (Agassiz, Seward Lobe, and Marvine) mean ice thinning was estimated at -47 m with maximum thinning on parts of the lobes to -160 m. The Malaspina's accumulation area is only slightly larger than its ablation area (2,575 km2 vs. 2,433 km2); unfortunately few glaciological observations are available from this source region. Snow accumulation rates have been largely inferred from low-altitude precipitation and temperature data. Comparing sequential ICESat observations in the Malaspina source region, we estimated short-term elevation increases of up to 5 meters during the winter of 2003/04.

Sauber, J.; Molnia, B.; Carabajal, C.; Luthcke, S.; Muskett, R.

2005-01-01

402

Wild Wind  

NSDL National Science Digital Library

Students learn the difference between global, prevailing and local winds. They make wind vanes out of paper, straws and soda bottles and use them to measure wind direction over time. They analyze their data to draw conclusions about the local prevailing winds.

Integrated Teaching And Learning Program

403

Complex Behaviour of Glaciers in Ladakh Mountains (J & K State, India) : Case Study  

NASA Astrophysics Data System (ADS)

The Ladakh Mountains house approximately 4500 glaciers in its two major basins, namely Indus (1800 glaciers) and Shyok (2700 glaciers).Glaciers in Indian Himalaya have been under monitor for past about five decades. Monitoring of scores of glaciers have been both in terms of documentary record and field studies of the glaciers in northwest Himalaya. The studies suggest that glaciers of Ladakh mountains show an extremely different behavior as compared to the glaciers of rest of northwest Himalaya. Four glaciers, namely Durung Drung, Kangriz, Machoi and Siachen, representing the Indus and Shyok basin are dealt herein. Sufficient documentary and field evidences of these four glaciers support the view that glaciers housed in Ladakh mountains contradict the commonly accepted concept of fast melting glaciers in Himalaya (Ganjoo and Koul 2009; Ganjoo et al. 2010). The studies further suggest that the secular movement of glaciers in Ladakh mountains is a complex phenomena of several micro and macro-climatic factors, terrain morphology, and tectonics (Ganjoo 2009, Koul and Ganjoo 2010). The change in the morphology of glaciers is not necessarily related with the change in climate as commonly believed and hyped. Ganjoo, R.K. (2009) Holocene Tectonics and Climate of Durung Drung Glacier Basin, Zanskar Himalaya, India (Abstract). The 5th International Symposium on Tibetan Plateau and 24th Himalaya- Karakorum-Tibet Workshop, Aug. 11-14, Beijing, China. Ganjoo, R.K. and Koul, M.N. (2009) Is the Siachen glacier melting? Current Science, 97(3), 309-310. Ganjoo, RK; Koul, MN; Ajai; Bahuguna, IM (2010) Glaciers of Nubra valley, Karakorum mountains, Ladakh (India) vis--vis climate change (abstract). 7th Annual Meeting of Asia Oceania Geosciences Society, Hyderabad. Koul, M.N. and Ganjoo, R.K. (2010) Impact of inter- and intra-annual variation in weather parameters on mass balance and equilibrium line altitude of Naradu glacier (Himachal Pradesh), NW Himalaya, India. Climatic Change, 99, 119-139.

Ganjoo, R. K.

2011-12-01

404

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

405

Svalbard glacier elevation changes and contribution to sea level rise  

NASA Astrophysics Data System (ADS)

We compare satellite altimetry from the Ice, Cloud, and Land Elevation Satellite (ICESat, 2003-2007) to older topographic maps and digital elevation models (1965-1990) to calculate long-term elevation changes of glaciers on the Svalbard Archipelago. Results indicate significant thinning at most glacier fronts with either slight thinning or thickening in the accumulation areas, except for glaciers that surged which show thickening in the ablation area and thinning in the accumulation areas. The most negative geodetic balances occur in the south and on glaciers that have surged, while the least negative balances occur in the northeast and on glaciers in the quiescent phase of a surge cycle. Geodetic balances are related to latitude and to the dynamical behavior of the glacier. The average volume change rate over the past 40 years for Svalbard, excluding Austfonna and Kvitya is estimated to be -9.71 0.55 km3 yr-1 or -0.36 0.02 m yr-1 w. equivalent, for an annual contribution to global sea level rise of 0.026 mm yr-1 sea level equivalent.

Nuth, Christopher; Moholdt, Geir; Kohler, Jack; Hagen, Jon Ove; KB, Andreas

2010-03-01

406

Calving on tidewater glaciers amplified by submarine frontal melting  

E-print Network

While it has been shown repeatedly that ocean conditions exhibit an important control on the behaviour of grounded tidewater glaciers, modelling studies have focused largely on the effects of basal and surface melting. Here, a finite-element model of stresses near the front of a tidewater glacier is used to investigate the effects of frontal melting on calving, independently of the calving criterion used. Applications of the stress model to idealized scenarios reveal that undercutting of the ice front due to frontal melting can drive calving at up to ten times the mean melt rate. Factors which cause increased frontal melt-driven calving include a strong thermal gradient in the ice, and a concentration of frontal melt at the base of the glacier. These properties are typical of both Arctic and Antarctic tidewater glaciers. The finding that frontal melt near the base is a strong driver of calving leads to the conclusion that water temperatures near the bed of the glacier are critically important to the glacier f...

O'Leary, Martin

2012-01-01

407

Glacier responses to recent volcanic activity in Southern Chile  

NASA Astrophysics Data System (ADS)

Glaciers in Southern Chile (39-43S) are characterized by frontal retreats and area losses in response to the ongoing climatic changes at a timescale of decades. Superimposed on these longer-term trends, volcanic activity is thought to impact glaciers in variable ways. Debris-ash covered Glaciar Pichillancahue-Turbio only retreated slightly in recent decades in spite of been located on Volcn Villarrica which has experienced increased volcanic activity since 1977. In contrast, the negative long-term Volcn Michinmahuida glacier area trend reversed shortly before the beginning of the explosive eruption of nearby Volcn Chaitn in May 2008, when Glaciar Amarillo advanced and a lahar type of mudflow was observed. This advancing process is analysed in connection to the nearby eruption, producing albedo changes at Michinmahuida glaciers, as well as a possible enhanced basal melting from higher geothermal flux. Deconvolution of glacier responses due to these processes is difficult and probably not possible with available data. Much more work and data are required to determine the causes of present glacier behaviour.

Rivera, Andrs; Bown, Francisca; Carrin, Daniela; Zenteno, Pablo

2012-03-01

408

Tropical glaciers and climate dynamics: Resolving the linkages  

NASA Astrophysics Data System (ADS)

Large-scale atmosphere/ocean circulation and mountain glaciers represent two entirely different scales in the climate system. Therefore, statistical linkages between the two mask a cascade of processes that act on different temporal and spatial dimensions. Low-latitude glaciers are particularly well suited for studying such processes, since these glaciers are situated in the "heart" of the global climate system (the tropics). This presentation gives an overview of a decade of research on tropical climate and glaciers on Kilimanjaro (East Africa), which is, to our knowledge, the only case where space/time linkages between high-altitude glaciers and climate dynamics have been investigated systematically throughout the main scales. This includes the complex modification of atmospheric flow when air masses impinge on high mountains, an aspect that has been widely neglected from a cryospheric viewpoint. The case of Kilimanjaro demonstrates (1) the great potential of learning about climate system processes and their connections, (2) advances in our understanding of the importance of moisture for glaciers that lie far above the mean freezing level, and (3) methodological advances in combining atmospheric and cryospheric modelling.

Mlg, Thomas

2013-04-01

409

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

410

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

411

Glacier inventory of the Gran Campo Nevado Ice Cap in the Southern Andes and glacier changes observed during recent decades  

Microsoft Academic Search

The Gran Campo Nevado (GCN) forms an isolated ice cap on the Pennsula Muoz Gamero (PMG) located 200km to the south of the Southern Patagonia Icefield (SPI). We present a glacier inventory of the GCN made up by 27 drainage basins (in total 199.5km2) and other small cirque and valley glaciers of the southern part of PMG (in total 53km2).

Christoph Schneider; Michael Schnirch; Csar Acua; Gino Casassa; Rolf Kilian

2007-01-01

412

Glaciers and rock glaciers distribution at 28 SL, Dry Andes of Argentina, and some considerations about their hydrological significance  

Microsoft Academic Search

The area studied includes a little-known portion on the Dry Andes of the San Juan Frontal Cordillera, Argentina, where the\\u000a hydrological significance of glaciers and rock glaciers was earlier never studied. The surveyed sector includes Cerro El Potro\\u000a (5,870m ASL) and nearby mountain chains (28S). The predominant landforms in these areas were shaped in a periglacial environment\\u000a superimposed on an

Laura Perucca; Mara Yanina Esper Angillieri

413

Potential regime shift in decreased sea ice production after the Mertz Glacier calving.  

PubMed

Variability in dense shelf water formation can potentially impact Antarctic Bottom Water (AABW) production, a vital component of the global climate system. In East Antarctica, the George V Land polynya system (142-150E) is structured by the local 'icescape', promoting sea ice formation that is driven by the offshore wind regime. Here we present the first observations of this region after the repositioning of a large iceberg (B9B) precipitated the calving of the Mertz Glacier Tongue in 2010. Using satellite data, we find that the total sea ice production for the region in 2010 and 2011 was 144 and 134?km(3), respectively, representing a 14-20% decrease from a value of 168?km(3) averaged from 2000-2009. This abrupt change to the regional icescape could result in decreased polynya activity, sea ice production, and ultimately the dense shelf water export and AABW production from this region for the coming decades. PMID:22569370

Tamura, T; Williams, G D; Fraser, A D; Ohshima, K I

2012-01-01

414

Wind effects on snow cover in Pascua-Lama, Dry Andes of Chile  

NASA Astrophysics Data System (ADS)

We present the application of a distributed snow model (SnowModel) on the instrumented site of Pascua-Lama in the Dry Andes (2600-5630 m above sea level, 29 S). A model experiment was performed to assess the effect of wind on snow cover patterns. A particular objective was to evaluate the role of blowing snow on the glacier formation. The model was run using the data from 11 weather stations over a complete snow season. First, a cross-validation of the meteorological variables interpolation model (MicroMet submodel) was performed to evaluate the performance of the simulated meteorological forcing. Secondly, two SnowModel simulations were set up: one without and the other with the wind transport submodel (SnowTran-3D). Results from both simulations were compared with in situ snow depth measurements and remotely sensed snow cover data. The inclusion of SnowTran-3D does not change the fact that the model is unable to capture the small-scale snow depth spatial variability (as captured by in situ snow depth sensors). However, remote sensing data (MODIS daily snow product) indicate that at broader scales the wind module produced an improved representation of the snow distribution near the glaciers (2-D correlation coefficient increased from R = 0.04 to R = 0.27). The model outputs show that a key process is the sublimation of blowing snow, which amounts to 18% of the total ablation over the whole study area, with a high spatial variability. The effect of snow drift is more visible on the glaciers, where wind-transported snow accumulates preferentially. Net deposition occurred for 43% of the glacier grid points, whereas it is only 23% of non-glacier grid points located above the minimum glacier altitude (4475 m).

Lhermitte, Stef; Gascoin, Simon; Kinnard, Christophe; Bortels, Kirsten; Liston, Glen E.

2013-04-01

415

Wind effects on snow cover in Pascua-Lama, Dry Andes of Chile  

NASA Astrophysics Data System (ADS)

We present the first application of a distributed snow model (SnowModel) in the instrumented site of Pascua-Lama in the Dry Andes (2600-5630 m above sea level, 29 S). A model experiment was performed to assess the effect of wind on the snow cover patterns. A particular objective was to evaluate the role of blowing snow on the glacier formation. The model was run using the data from 11 weather stations over a complete snow season. First, a cross-validation of the meteorological variables interpolation model (MicroMet submodel) was performed to evaluate the performance of the simulated meteorological forcing. Secondly, two SnowModel simulations were set up: one without and the other with the wind transport submodel (SnowTran-3D). Results from both simulations were compared with in situ snow depth measurements and remotely sensed snow cover data. The inclusion of SnowTran-3D does not change the fact that the model is unable to capture the small-scale snow depth spatial variability (as captured by in situ snow depth sensors). However, remote sensing data (MODIS daily snow product) indicate that at broader scales the wind module produced an improved representation of the snow distribution near the glaciers (2-D correlation coefficient increased from R = 0.04 to R = 0.27). The model outputs show that a key process is the sublimation of blowing snow, which amounts to 18% of the total ablation over the whole study area, with a high spatial variability. The effect of snow drift is more visible on the glaciers, where wind-transported snow accumulates preferentially. Net deposition occurred for 43% of the glacier grid points, whereas it is only 23% of non-glacier grid points located above the minimum glacier altitude (4475 m).

Gascoin, Simon; Lhermitte, Stefaan; Kinnard, Christophe; Bortels, Kirsten; Liston, Glen E.

2013-05-01

416

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

417

Exploring the mobility of cryoconite on High-Arctic glaciers  

NASA Astrophysics Data System (ADS)

There has been a growing awareness of the significance of biologically active dust (cryoconite) on the energy balance of, and nutrient cycling at glacier surfaces. Moreover, researchers have estimated the mass of biological material released from glacier ice to downstream environments and ecosystems, including the melt-out of cells from emergent ice in the ablation area. However, the processes, rates and mechanisms of cryoconite mobility and transport have not been fully explored. For many smaller valley glaciers in the High-Arctic, the climate dictates only a thin (~ 1m) layer of ice at the glacier surface is at the melting point during the summer months. This surface ice is commonly characterized by an increased porosity in response to incident energy and hydraulic conditions, and has been termed the weathering crust. The presence of cryoconite, with its higher radiation absorption, exacerbates the weathering crust development. Thus, crucially, the transport of cryoconite is not confined to simply a smooth ice surface, but rather also includes mobility in the near-surface ice matrix. Here, we present initial results from investigations of cryoconite transport at Midtre Lovnbreen and Longyearbreen, two north-facing valley glaciers in Svalbard (Norway). Using time-lapse imagery, we explore the transport rates of cryoconite on a glacier surface and consider the associations between mobility and meteorological conditions. Results suggest some disparity between micro-, local- and plot-scale observations of cryoconite transport: the differences imply controlling influences of cryoconite volume, ice surface topography and ice structure. While to examine the relative volumes of cryoconite exported from the glacier surface by supraglacial streams we employ flow cytometry, using SYBR-Green-II staining to identify the biological component of the suspended load. Preliminary comparisons between shallow (1m) ice cores and in-stream concentrations suggest cryoconite may be retained within the near-surface ice rather than being readily transported from the glacier by meltwater flows. We propose these processes lead to a reduced cell flux transported by meltwaters from the glacier to aquatic ecosystems, but an increase in the volume of cryoconite deposited in the forefield of a retreating glacier and made available for terrestrial ecosystem development.

Irvine-Fynn, T. D.; Hodson, A. J.; Bridge, J. W.; Langford, H.; Anesio, A.; Ohlanders, N.; Newton, S.

2010-12-01

418

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

419

Sediment connectivity evolution on an alpine catchment undergoing glacier retreat  

NASA Astrophysics Data System (ADS)

Climate changes can result in a wide range of variations of natural environment including retreating glaciers. Melting from glaciers will have a significant impact on the sediment transport characteristics of glacierized alpine catchments that can affect downstream channel network. Sediment connectivity assessment, i.e. the degree of connections that controls sediment fluxes between different segments of a landscape, can be useful in order to address management activity on sediment fluxes changes of alpine streams. Through the spatial characterization of the connectivity patterns of a catchment and its potential evolution it is possible to both define sediment transport pathways and estimate different contributions of the sub-catchment as sediment sources. In this study, a topography based index (Cavalli et al., 2013) has been applied to assess spatial sediment connectivity in the Navisence catchment (35 km2), an alpine basin located in the southern Walliser Alps (Switzerland) characterized by a complex glacier system with well-developed lateral moraines on glacier margins already crossed by several lateral channels. Glacier retreat of the main glacial edifice will provide a new connectivity pattern. At present the glacier disconnects lateral slopes from the main talweg: it is expected that its retreat will experience an increased connectivity. In order to study this evolution, two high resolution (2 m) digital terrain models (DTMs) describing respectively the terrain before and after glacier retreat have been analyzed. The current DTM was obtained from high resolution photogrammetry (2 m resolution). The future DTM was derived from application of the sloping local base level (SLBL) routine (Jaboyedoff et al., 2004) on the current glacier system, allowing to remove the ice body by reconstituting a U-shaped polynomial bedrock surface. From this new surface a coherent river network was drawn and slight random noise was added. Finally the river network was burned into the rough surface of the SLBL results. The impact of sediment dynamic changes on the study catchment due to glacier retreat has been assessed by comparing predictions deriving from model application on different scenarios. Simulations allowed the analysis of sediment connectivity evolution over decade scales suggesting an increase of potential sediment transfer and connections in areas close to the main channel network. References: Cavalli, M., Trevisani, S., Comiti, F., Marchi, L., 2013. Geomorphometric assessment of spatial sediment connectivity in small Alpine catchments. Geomorphology 188, 31-41. Jaboyedoff M., Bardou E., Derron M.-H. 2004. Sloping local base level: a tool to estimate potential erodible volume and infilling alluvial sediment of glacial valleys. Swiss Geo-Scientists meeting, November 2004, Lausanne.

Goldin, Beatrice; Rudaz, Benjamin; Bardou, Eric

2014-05-01

420

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

E-print Network

??The glaciers surrounding the Blackstone-Spencer Ice Complex display a variety of termini types: Tebenkov, Spencer, Bartlett, Skookum, Trail, Burns, Shakespeare, Marquette, Lawrence, and Ripon glaciers (more)

Crossen, Kristine June

1997-01-01

421

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 and 2008. 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. y-1 for the period 2003-2008, 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 glacierets and glaciers.

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

2010-11-01

422

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

423

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

424

Glacier changes in the Karakoram region mapped by multi-mission satellite imagery  

NASA Astrophysics Data System (ADS)

Glaciers in the Karakoram region are known to show stable and advancing terminus positions or surging behavior, which contrasts the worldwide retreat of many mountain glaciers. The present study uses Landsat imagery to derive an updated and extended glacier inventory. Surging and advancing glaciers and their annual termini position changes are mapped in addition. Out of 1334 glaciers, 134 show advancing or surging behavior, with a marked increase since 2000. The length distribution of surging glaciers differs significantly from non-surging glaciers. More than 50% of the advancing/surging glaciers are shorter than 10 km. Besides a regional spatial coverage of ice dynamics, high-resolution SAR data allows to investigate very small and comparably fast flowing glaciers (up to 1.8 m day-1). Such data enables mapping of temporal changes of ice dynamics of individual small surging or advancing glaciers. In a further case study, glacier volume changes of three glaciers around Braldu Glacier are quantified during a surge event comparing digital elevation models from the Shuttle Radar Topography Mission (SRTM) and the new TerraSAR-X add-on for Digital Elevation Measurement (TanDEM-X) Mission. We recommend regular acquisitions of high resolution (bi-static) SAR satellite data and further exploitation of the archives in order to generate an improved database for monitoring changes, and to at least partially compensate for the lack of in-situ and long-term climatological measurements in the Karakoram region.

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

2013-08-01

425

A new glacier inventory for 2009 reveals spatial and temporal variability in glacier response to atmospheric warming in the Northern Antarctic Peninsula, 1988-2009  

NASA Astrophysics Data System (ADS)

The Northern Antarctic Peninsula has recently exhibited ice-shelf disintegration, glacier recession and acceleration. However, the dynamic response of land-terminating, ice-shelf tributary and tidewater glaciers has not yet been quantified or assessed for variability, and there are sparse published data for glacier classification, morphology, area, length or altitude. This paper firstly uses ASTER images from 2009 and a SPIRIT DEM from 2006 to classify the area, length, altitude, slope, aspect, geomorphology, type and hypsometry of 194 glaciers on Trinity Peninsula, Vega Island and James Ross Island. Secondly, this paper uses LANDSAT-4 and ASTER images from 1988 and 2001 and data from the Antarctic Digital Database (ADD) from 1997 to document glacier change 1988-2009. From 1988-2001, 90 % of glaciers receded, and from 2001-2009, 79 % receded. Glaciers on the western side of Trinity Peninsula retreated relatively little. On the eastern side of Trinity Peninsula, the rate of recession of ice-shelf tributary glaciers has slowed from 12.9 km2 a-1 (1988-2001) to 2.4 km2 a-1 (2001-2009). Tidewater glaciers on the drier, cooler Eastern Trinity Peninsula experienced fastest recession from 1988-2001, with limited frontal retreat after 2001. Land-terminating glaciers on James Ross Island also retreated fastest in the period 1988-2001. Large tidewater glaciers on James Ross Island are now declining in areal extent at rates of up to 0.04 km2 a-1. This east-west difference is largely a result of orographic temperature and precipitation gradients across the Antarctic Peninsula. Strong variability in tidewater glacier recession rates may result from the influence of glacier length, altitude, slope and hypsometry on glacier mass balance. High snowfall means that the glaciers on the Western Peninsula are not currently rapidly receding. Recession rates on the eastern side of Trinity Peninsula are slowing as the floating ice tongues retreat into the fjords and the glaciers reach a new dynamic equilibrium. The rapid glacier recession of tidewater glaciers on James Ross Island is likely to continue because of their low elevations and flat profiles. In contrast, the higher and steeper tidewater glaciers on the Eastern Antarctic Peninsula will attain more stable frontal positions after low-lying ablation areas are removed.

Davies, B. J.; Carrivick, J. L.; Glasser, N. F.; Hambrey, M. J.; Smellie, J. L.

2011-12-01

426

Characterisation of glacier facies with the Airborne Thematic Mapper  

NASA Astrophysics Data System (ADS)

Here we present preliminary work using multispectral imagery from the Airborne Thematic Mapper (ATM) to build a classification scheme for surface zones of arctic glaciers and icecaps constrained by recently collected data. Previous studies of snow spectral response indicates that the ATMs spectral and spatial resolution will allow for sensitivity in measuring the important but elusive firn line. In design, the ATM is similar to Landsats Enhanced Thematic Mapper but with key improvements to spatial (potential submeter vs. 30 m) and spectral (a near infrared band 0.91-1.05 ?m) resolution. Published studies have used Landsat imagery and methods such as spectral band ratios, normalized indices, thresholding, principle component analysis, unsupervised classifications, supervised classification, and spectral mixing analysis to classify glacier surfaces. This research builds on these promising techniques with the application of new ATM data and potentially the integration of associated surface elevation data where appropriate with the goal of successfully and reliably identifying the extent of major glacier facies. Compounding the already problemati