Perennial Water Stratification and the Role of Basal Freshwater Flow in the Mass Balance of the Ward Hunt Ice Shelf, Canadian High Arctic
A pronounced perennial water stratification in Disraeli Fjord behind the Ward Hunt Ice Shelf on the north coast of Ellesmere Island is described. 'ne ice shelf acts as a hanging dam at the mouth of the fjord and minimizes mixing between inflowing meltwater runoff and the seawater. Consequently,...
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ftdtic:ADP007307 2023-05-15T15:19:20+02:00 Perennial Water Stratification and the Role of Basal Freshwater Flow in the Mass Balance of the Ward Hunt Ice Shelf, Canadian High Arctic Jefferies, Martin O. ALASKA UNIV FAIRBANKS GEOPHYSICAL INST 1992-03 text/html http://www.dtic.mil/docs/citations/ADP007307 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADP007307 en eng http://www.dtic.mil/docs/citations/ADP007307 APPROVED FOR PUBLIC RELEASE DTIC AND NTIS Atmospheric Physics Physical and Dynamic Oceanography Snow Ice and Permafrost *ICE ISLANDS *WATER FLOW ABLATION ACCUMULATION DAMS DELTAS ELLESMERE ISLAND FEEDBACK FJORDS ICE LAYERS MELTING MIXING PRECIPITATION RECORDS RUNOFF SALINITY STRATIFICATION THICKNESS TRITIUM VALUE GREENHOUSE EFFECT ENVIRONMENTAL IMPACT *Global climate change Component Reports Text 1992 ftdtic 2016-02-19T17:39:30Z A pronounced perennial water stratification in Disraeli Fjord behind the Ward Hunt Ice Shelf on the north coast of Ellesmere Island is described. 'ne ice shelf acts as a hanging dam at the mouth of the fjord and minimizes mixing between inflowing meltwater runoff and the seawater. Consequently, a 4 1 -m-deep layer of low salinity water, interposed between a 2- to 3-m-thick fjord surface ice layer and deeper seawater, is impounded behind the ice shelf. Highly negative delta 18O Values and high tritium activity in the low salinity water indicate it is derived primarily from snow-meltwater. Highly negative delta 18O values and high tritium values in a 5-m-thick basal ice layer in Hobson's Choice Ice Island, which broke off the East Ward Hunt Ice Shelf in 1982-83, might be evidence that basal accretion from freshwater flowing out of Disraeli Fjord below the ice shelf occurred prior to the calving. Using the known chronology of tritium occurrence in precipitation since 1952 and the measured levels in the basal ice, mean basal accretion rates of 96-141 mm yr-1 (water equivalent, w.e.) are calculated. The record of ablation and accumulation at the surface of the East Ward Hunt Ice Shelf for the period 1966-1982 shows an accumulated loss at the surface of 1.26 m (w.e.) at a mean annual rate of 74 mm yr-1. Therefore, despite many consecutive warm summers with considerable surface melting and runoff, the calculated basal accretion exceeds the surface loss and the ice shelf has increased, or at least maintained, its thickness. The thickening has been possible because of the feedback system created by the location of the ice shelf across the mouth of the fjord, the resultant water stratification and the outflow of freshwater below the ice shelf. This article is from 'Proceedings of the International Conference on the Role of whe Polar Regions in Global Change Held in Fairbanks, Alaska on 11-15 June 1990. Volume 1', AD-A253 027, p332-337. See also Volume 2, AD-A253 028. Text Arctic Climate change Ellesmere Island Ice Ice Shelf permafrost Ward Hunt Ice Shelf Alaska Defense Technical Information Center: DTIC Technical Reports database Arctic Fairbanks Ellesmere Island Ward Hunt Ice Shelf ENVELOPE(-73.499,-73.499,83.122,83.122) |
institution |
Open Polar |
collection |
Defense Technical Information Center: DTIC Technical Reports database |
op_collection_id |
ftdtic |
language |
English |
topic |
Atmospheric Physics Physical and Dynamic Oceanography Snow Ice and Permafrost *ICE ISLANDS *WATER FLOW ABLATION ACCUMULATION DAMS DELTAS ELLESMERE ISLAND FEEDBACK FJORDS ICE LAYERS MELTING MIXING PRECIPITATION RECORDS RUNOFF SALINITY STRATIFICATION THICKNESS TRITIUM VALUE GREENHOUSE EFFECT ENVIRONMENTAL IMPACT *Global climate change Component Reports |
spellingShingle |
Atmospheric Physics Physical and Dynamic Oceanography Snow Ice and Permafrost *ICE ISLANDS *WATER FLOW ABLATION ACCUMULATION DAMS DELTAS ELLESMERE ISLAND FEEDBACK FJORDS ICE LAYERS MELTING MIXING PRECIPITATION RECORDS RUNOFF SALINITY STRATIFICATION THICKNESS TRITIUM VALUE GREENHOUSE EFFECT ENVIRONMENTAL IMPACT *Global climate change Component Reports Jefferies, Martin O. Perennial Water Stratification and the Role of Basal Freshwater Flow in the Mass Balance of the Ward Hunt Ice Shelf, Canadian High Arctic |
topic_facet |
Atmospheric Physics Physical and Dynamic Oceanography Snow Ice and Permafrost *ICE ISLANDS *WATER FLOW ABLATION ACCUMULATION DAMS DELTAS ELLESMERE ISLAND FEEDBACK FJORDS ICE LAYERS MELTING MIXING PRECIPITATION RECORDS RUNOFF SALINITY STRATIFICATION THICKNESS TRITIUM VALUE GREENHOUSE EFFECT ENVIRONMENTAL IMPACT *Global climate change Component Reports |
description |
A pronounced perennial water stratification in Disraeli Fjord behind the Ward Hunt Ice Shelf on the north coast of Ellesmere Island is described. 'ne ice shelf acts as a hanging dam at the mouth of the fjord and minimizes mixing between inflowing meltwater runoff and the seawater. Consequently, a 4 1 -m-deep layer of low salinity water, interposed between a 2- to 3-m-thick fjord surface ice layer and deeper seawater, is impounded behind the ice shelf. Highly negative delta 18O Values and high tritium activity in the low salinity water indicate it is derived primarily from snow-meltwater. Highly negative delta 18O values and high tritium values in a 5-m-thick basal ice layer in Hobson's Choice Ice Island, which broke off the East Ward Hunt Ice Shelf in 1982-83, might be evidence that basal accretion from freshwater flowing out of Disraeli Fjord below the ice shelf occurred prior to the calving. Using the known chronology of tritium occurrence in precipitation since 1952 and the measured levels in the basal ice, mean basal accretion rates of 96-141 mm yr-1 (water equivalent, w.e.) are calculated. The record of ablation and accumulation at the surface of the East Ward Hunt Ice Shelf for the period 1966-1982 shows an accumulated loss at the surface of 1.26 m (w.e.) at a mean annual rate of 74 mm yr-1. Therefore, despite many consecutive warm summers with considerable surface melting and runoff, the calculated basal accretion exceeds the surface loss and the ice shelf has increased, or at least maintained, its thickness. The thickening has been possible because of the feedback system created by the location of the ice shelf across the mouth of the fjord, the resultant water stratification and the outflow of freshwater below the ice shelf. This article is from 'Proceedings of the International Conference on the Role of whe Polar Regions in Global Change Held in Fairbanks, Alaska on 11-15 June 1990. Volume 1', AD-A253 027, p332-337. See also Volume 2, AD-A253 028. |
author2 |
ALASKA UNIV FAIRBANKS GEOPHYSICAL INST |
format |
Text |
author |
Jefferies, Martin O. |
author_facet |
Jefferies, Martin O. |
author_sort |
Jefferies, Martin O. |
title |
Perennial Water Stratification and the Role of Basal Freshwater Flow in the Mass Balance of the Ward Hunt Ice Shelf, Canadian High Arctic |
title_short |
Perennial Water Stratification and the Role of Basal Freshwater Flow in the Mass Balance of the Ward Hunt Ice Shelf, Canadian High Arctic |
title_full |
Perennial Water Stratification and the Role of Basal Freshwater Flow in the Mass Balance of the Ward Hunt Ice Shelf, Canadian High Arctic |
title_fullStr |
Perennial Water Stratification and the Role of Basal Freshwater Flow in the Mass Balance of the Ward Hunt Ice Shelf, Canadian High Arctic |
title_full_unstemmed |
Perennial Water Stratification and the Role of Basal Freshwater Flow in the Mass Balance of the Ward Hunt Ice Shelf, Canadian High Arctic |
title_sort |
perennial water stratification and the role of basal freshwater flow in the mass balance of the ward hunt ice shelf, canadian high arctic |
publishDate |
1992 |
url |
http://www.dtic.mil/docs/citations/ADP007307 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADP007307 |
long_lat |
ENVELOPE(-73.499,-73.499,83.122,83.122) |
geographic |
Arctic Fairbanks Ellesmere Island Ward Hunt Ice Shelf |
geographic_facet |
Arctic Fairbanks Ellesmere Island Ward Hunt Ice Shelf |
genre |
Arctic Climate change Ellesmere Island Ice Ice Shelf permafrost Ward Hunt Ice Shelf Alaska |
genre_facet |
Arctic Climate change Ellesmere Island Ice Ice Shelf permafrost Ward Hunt Ice Shelf Alaska |
op_source |
DTIC AND NTIS |
op_relation |
http://www.dtic.mil/docs/citations/ADP007307 |
op_rights |
APPROVED FOR PUBLIC RELEASE |
_version_ |
1766349510548652032 |