The mass balance and the flow of a polythermal glacier, McCall Glacier, Brooks Range, Alaska
Dissertation (Ph.D.) University of Alaska Fairbanks, 1997 Studies of surface motion and geometry, ice thickness, and mass balance were carried out on the arctic McCall Glacier. They revealed characteristic processes of glacier flow and mass balance that independently reflect the polythermal temperat...
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ftunivalaska:oai:scholarworks.alaska.edu:11122/9498 2023-05-15T15:02:17+02:00 The mass balance and the flow of a polythermal glacier, McCall Glacier, Brooks Range, Alaska Rabus, Bernhard Theodor Echelmeyer, Keith 1997 http://hdl.handle.net/11122/9498 unknown http://hdl.handle.net/11122/9498 Geophysics Dissertation phd 1997 ftunivalaska 2023-02-23T21:37:17Z Dissertation (Ph.D.) University of Alaska Fairbanks, 1997 Studies of surface motion and geometry, ice thickness, and mass balance were carried out on the arctic McCall Glacier. They revealed characteristic processes of glacier flow and mass balance that independently reflect the polythermal temperature regime of the glacier, which consists of cold ice except for a discontinuous layer of temperate ice at the base. Analysis of the present flow of McCall Glacier showed the longitudinal stress coupling length to be significantly larger than on temperate glaciers. This is a consequence of the smaller mass balance gradients and associated lower strain rates of arctic glaciers. Furthermore, flow analysis suggests year-round basal sliding beneath a section of the lower glacier, which accounts for more than 70% of the total motion. This sliding anomaly is reflected in corresponding anomalies of the observed ice thickness and surface profiles. Changes in surface velocity, both on a decadal and on a seasonal scale, were also studied. Velocities during the short summer season increase by up to 75% above winter values as a result of enhanced basal sliding at the temperate glacier bed. The zone affected by this speed-up extends upglacier of any obvious sources of meltwater input to the bed. The mass balance of McCall Glacier exhibits a trend towards increasingly negative values. This is shown by both annual measurements during 1969-72 and 1993-96 and by comparing long-term values for two periods, 1957-71 and 1972-93. The contribution of refreezing surface water in the cold surface layers of firn and ice (internal accumulation) to the net accumulation was found to increase from about 40% in the 1970s to more than 90% in the 1990s. Comparative studies of long-term volume changes of neighboring glaciers showed that the McCall Glacier mass balance is regionally representative. Existing good correlations of the mass balance with meteorological parameters recorded by a weather station more than 400 km to the east furthermore ... Doctoral or Postdoctoral Thesis Arctic Brooks Range glacier glaciers Alaska University of Alaska: ScholarWorks@UA Arctic Fairbanks McCall ENVELOPE(-66.619,-66.619,-67.029,-67.029) |
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University of Alaska: ScholarWorks@UA |
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unknown |
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Geophysics |
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Geophysics Rabus, Bernhard Theodor The mass balance and the flow of a polythermal glacier, McCall Glacier, Brooks Range, Alaska |
topic_facet |
Geophysics |
description |
Dissertation (Ph.D.) University of Alaska Fairbanks, 1997 Studies of surface motion and geometry, ice thickness, and mass balance were carried out on the arctic McCall Glacier. They revealed characteristic processes of glacier flow and mass balance that independently reflect the polythermal temperature regime of the glacier, which consists of cold ice except for a discontinuous layer of temperate ice at the base. Analysis of the present flow of McCall Glacier showed the longitudinal stress coupling length to be significantly larger than on temperate glaciers. This is a consequence of the smaller mass balance gradients and associated lower strain rates of arctic glaciers. Furthermore, flow analysis suggests year-round basal sliding beneath a section of the lower glacier, which accounts for more than 70% of the total motion. This sliding anomaly is reflected in corresponding anomalies of the observed ice thickness and surface profiles. Changes in surface velocity, both on a decadal and on a seasonal scale, were also studied. Velocities during the short summer season increase by up to 75% above winter values as a result of enhanced basal sliding at the temperate glacier bed. The zone affected by this speed-up extends upglacier of any obvious sources of meltwater input to the bed. The mass balance of McCall Glacier exhibits a trend towards increasingly negative values. This is shown by both annual measurements during 1969-72 and 1993-96 and by comparing long-term values for two periods, 1957-71 and 1972-93. The contribution of refreezing surface water in the cold surface layers of firn and ice (internal accumulation) to the net accumulation was found to increase from about 40% in the 1970s to more than 90% in the 1990s. Comparative studies of long-term volume changes of neighboring glaciers showed that the McCall Glacier mass balance is regionally representative. Existing good correlations of the mass balance with meteorological parameters recorded by a weather station more than 400 km to the east furthermore ... |
author2 |
Echelmeyer, Keith |
format |
Doctoral or Postdoctoral Thesis |
author |
Rabus, Bernhard Theodor |
author_facet |
Rabus, Bernhard Theodor |
author_sort |
Rabus, Bernhard Theodor |
title |
The mass balance and the flow of a polythermal glacier, McCall Glacier, Brooks Range, Alaska |
title_short |
The mass balance and the flow of a polythermal glacier, McCall Glacier, Brooks Range, Alaska |
title_full |
The mass balance and the flow of a polythermal glacier, McCall Glacier, Brooks Range, Alaska |
title_fullStr |
The mass balance and the flow of a polythermal glacier, McCall Glacier, Brooks Range, Alaska |
title_full_unstemmed |
The mass balance and the flow of a polythermal glacier, McCall Glacier, Brooks Range, Alaska |
title_sort |
mass balance and the flow of a polythermal glacier, mccall glacier, brooks range, alaska |
publishDate |
1997 |
url |
http://hdl.handle.net/11122/9498 |
long_lat |
ENVELOPE(-66.619,-66.619,-67.029,-67.029) |
geographic |
Arctic Fairbanks McCall |
geographic_facet |
Arctic Fairbanks McCall |
genre |
Arctic Brooks Range glacier glaciers Alaska |
genre_facet |
Arctic Brooks Range glacier glaciers Alaska |
op_relation |
http://hdl.handle.net/11122/9498 |
_version_ |
1766334257964253184 |