Glaciology Commons^™

Interferometric Swath Processing Of Cryosat Data For Glacial Ice Topography, L. Gray, D. Burgess, L. Copland, R. Cullen, N. Galin, R. Hawley, V. Helm

Dartmouth Scholarship

We have derived digital elevation models (DEMs) over the western part of the Devon Ice Cap in Nunavut, Canada, using "swath processing" of interferometric data collected by Cryosat between February 2011 and January 2012. With the standard ESA (European Space Agency) SARIn (synthetic aperture radar interferometry) level 2 (L2) data product, the interferometric mode is used to map the cross-track position and elevation of the "point-of-closest-approach" (POCA) in sloping glacial terrain. However, in this work we explore the extent to which the phase of the returns in the intermediate L1b product can also be used to map the heights of …

Transition In The Fractal Geometry Of Arctic Melt Ponds, C. Hohenegger, B. Alali, K. R. Steffen, D. K. Perovich, K. M. Golden

Dartmouth Scholarship

During the Arctic melt season, the sea ice surface undergoes a remarkable transformation from vast expanses of snow covered ice to complex mosaics of ice and melt ponds. Sea ice albedo, a key parameter in climate modeling, is determined by the complex evolution of melt pond configurations. In fact, ice–albedo feedback has played a major role in the recent declines of the summer Arctic sea ice pack. However, understanding melt pond evolution remains a significant challenge to improving climate projections. By analyzing area–perimeter data from hundreds of thousands of melt ponds, we find here an unexpected separation of scales, where …

Collaborative Research: Chronology Of Ice Fluctuations In The South Shetland Islands Since The Last Glacial Maximum, Brenda L. Hall

University of Maine Office of Research Administration: Grant Reports

This award supports a study of the timing of climate changes in the Southern Hemisphere with the goal of reconstructing former ice extent and fluctuations, as well as paleoclimate, along the key latitudinal transect from temperate Tierra del Fuego to the polar Antarctic Peninsula. Samples already in hand will allow the dating of ice fluctuations in the South Shetland Islands (SSI), a critical location where that transect crosses the Antarctic Convergence. Surprisingly little concrete evidence exists concerning former ice extent in the island chain. The results of this study will answer a number of basic questions regarding ice extent and …

Satellite Remote Sensing Of Glaciers And Ice Caps In Svalbard, Eurasian High Arctic, Gordon S. Hamilton

University of Maine Office of Research Administration: Grant Reports

Recent compilations of climate-related observations show that important changes are now underway in the High Arctic, probably as a response to anthropogenic greenhouse gas emissions over the last approximately 250 years. These changes include warming of the troposphere, reductions in sea ice cover, decreases in snow cover area, warming of tundra permafrost, and negative mass balances of glaciers and ice caps. In many instances, observations of change are relatively short in duration or sparse in spatial extent. The Principal Investigators will study glacier and ice cap variations over the approximately last 80 years and at a large scale on Svalbard. …

A New Mt. Logan Ice Core Record - Change In Climate And Chemistry Of The Atmosphere For The North Pacific, Paul Andrew Mayewski, Gregory Zielinski, Karl J. Kreutz, Andrei V. Kurbatov

University of Maine Office of Research Administration: Grant Reports

Mt. Logan, in the St. Elias Range, southeast Alaska, offers a unique opportunity for monitoring climate change and change in the atmospheric chemistry of the Gulf of Alaska and the North Pacific. In 1980, a 103-meter (M) ice core was recovered from Mt. Logan which spanned AD 1689-1980. It revealed well-defined annual layers, calibrated through the identification of radioactive bomb and volcanic horizons, allowing continuous, sub-seasonal sampling for stable isotopes and ion chemistry. The -29 degree C mean annual temperature at the site assures that the soluble, insoluble, and isotopic components of the core are well preserved.

In 2001 and …

Glaciology Of Blue Ice Areas In Antarctica, Gordon Hamilton

University of Maine Office of Research Administration: Grant Reports

A 'horizontal ice core' was collected at the Mount Moulton blue ice field in West Antarctica and preliminary analyses of the sample material suggests that a ~500 kyr climate record is preserved in the ice at this site. This award will contribute to the understanding of the Mt Moulton record by assessing the potential for ice-flow induced deformation of the stratigraphic profile. In addition, this award builds on the recognition of blue ice areas as archives of long climate records by conducting reconnaissance studies for a potential horizontal ice core location at the Allan Hills in East Antarctica. The objectives …

A Science Management Office For The U. S. Component Of The International Trans Antarctic Expedition (Us Itase Smo)Ûa Collaborative Pgrm Of Research From S. Pole To N. Victoria Land, Paul A. Mayewski, Gordon S. Hamilton

University of Maine Office of Research Administration: Grant Reports

This award supports a science management office for a pilot ice-core drilling and analysis program to test the feasibility of obtaining well-dated, high-resolution isotope and chemistry records from East Antarctica. Shallow ice cores will be obtained from two locations: 1) ~100 km from South Pole towards the Pole of Inaccessibility, as an extension of the Byrd Station-to-South Pole ITASE traverse [International Trans Antarctic Scientific Expedition]; 2) at Taylor Dome, near the original deep coring site, and (3) possibly at AGO 3 and AGO 4 as part of a logistics traverse to these sites. All of the cores collected will be …

Glacial History Of The Amundsen Sea Shelf, Thomas B. Kellogg, Daniel Belknap, Davida Kellogg, Terence Hughes

University of Maine Office of Research Administration: Grant Reports

This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports a marine geological investigation of the Amundsen Sea region toward a better understanding of the deglaciation history of the West Antarctic Ice Sheet (WAIS). The WAIS may be inherently unstable because it is the last marine-based ice sheet in the world. Unlike other embayments in West Antarctica, major ice streams draining into the Amundsen Sea from the interior of the WAIS lack buttressing ice shelves. Mass balance data for the distal portions of these ice streams (Pine Island and Thwaites glaciers) appear to …

A New Ice Core From The Devon Ice Cap Canadian Arctic: Continued Development Of High-Resolution Proxy Records To Evaluate The Regionalization Of Climate In The Circum-Arctic, George A. Zielinski, Cameron Wake

University of Maine Office of Research Administration: Grant Reports

The primary goal of this project was to collect an ice core from the Summit of the Devon Ice Cap, Devon Island, Canadian Arctic. A 302-m core was collected during the spring of 1998 with additional field work in 1999. Individuals supported by this grant participated in the field work, although the GSC did the actual drilling. Glacier flow models as well as physical characteristics of the ice and d18O records suggest that basal ice recovered is about 86,000 years old. The first 200 meters were collected under dry drilling conditions, whereas the final 52 meters were collected with a …

Examination Of The 500,000-Year Climate Record In Ice At Mt. Moulton, West Antarctica, Gregory A. Zielinski, Paul Andrew Mayewski

University of Maine Office of Research Administration: Grant Reports

This project was a pilot project to determine if the ice on Mt. Moulton provides a reliable record of past climatic conditions. The area of study is a several hundred-meter section of blue ice (Trench A) that spans the time period from approximately the early Holocene to over 492k years ago. Dating control is obtained through radiometrically-dated tephra layers (i.e., air fall deposits) within the section (Figure 1) originating from the adjacent Mt. Berlin. Fieldwork during the 1999-2000 field season included the trenching of the complete section with electric chain saws mounted on a wheeled frame. Blocks were extracted and …

Acquisition Of Ion Chromatographs And Related Glaciochemistry Equipment, Paul Andrew Mayewski

University of Maine Office of Research Administration: Grant Reports

The goal of this project has been to upgrade the ice core processing and analytical equipment. This has been accomplished in three major areas: the design and construction of an ice core lathe, develpoment of a continuous melting system, and new ion chromatographs. The lathe is a unique ice core processing tool that operates similiar to a wood lathe. The lathe will reduce or eliminate the need for the cores to be hand scraped, the first cleaning step of core preparation.

Our continuous melting system is a modification of existing designs. Unlike other systems, we will collect discrete samples for …