Buoyancy-driven lacustrine calving, Glaciar Nef, Chilean Patagonia
Glaciar Nef, a 164 km(2) eastern outlet of Hielo Patagonico Norte (the northern Patagonia icefield), terminates in a proglacial lake that has formed in conjunction with 20th-century glacier retreat. The terminus is inferred to be transiently afloat. A hinge-calving mechanism is proposed in which buo...
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ftunstandrewcris:oai:risweb.st-andrews.ac.uk:publications/8eeaced2-bf4c-43f2-bb5a-4bf37d8d8263 2023-05-15T16:20:27+02:00 Buoyancy-driven lacustrine calving, Glaciar Nef, Chilean Patagonia Warren, Charles Raymond Benn, DI Winchester, V Harrison, S 2001-01 https://risweb.st-andrews.ac.uk/portal/en/researchoutput/buoyancydriven-lacustrine-calving-glaciar-nef-chilean-patagonia(8eeaced2-bf4c-43f2-bb5a-4bf37d8d8263).html http://www.scopus.com/inward/record.url?scp=0034857168&partnerID=8YFLogxK eng eng info:eu-repo/semantics/restrictedAccess Warren , C R , Benn , DI , Winchester , V & Harrison , S 2001 , ' Buoyancy-driven lacustrine calving, Glaciar Nef, Chilean Patagonia ' , Journal of Glaciology , vol. 47 , no. 156 , pp. 135-146 . INTERFEROMETRIC RADAR OBSERVATIONS COOK NATIONAL-PARK SOUTHERN PATAGONIA NEW-ZEALAND TIDEWATER GLACIER COLUMBIA GLACIER SAN-RAFAEL ICEFIELD ALASKA ICE article 2001 ftunstandrewcris 2021-12-26T14:11:21Z Glaciar Nef, a 164 km(2) eastern outlet of Hielo Patagonico Norte (the northern Patagonia icefield), terminates in a proglacial lake that has formed in conjunction with 20th-century glacier retreat. The terminus is inferred to be transiently afloat. A hinge-calving mechanism is proposed in which buoyant forces impose a torque on the glacier tongue, resulting in the release of coherent sections of the glacier tongue as "tabular" icebergs. A simple model shows how torque and tensile stress reach a maximum at the up-glacier limit of the buoyant zone, and that glacier thinning causes this point to migrate up-glacier Empirical evidence supporting this model includes elevated thermo-erosional notches less than or equal to 6.5 in above lake level, and the ubiquitous presence since 1975 of "tabular" icebergs with surface areas < 0.3 km(2). Flow speeds of 1.2-1.3 m d(-1) were measured near the terminus in February 1998. Extrapolations from these short-term data yield a calving rate of 785-835 m a(-1) and a calving flux of 232 x 10(6) m(3) a(-1) or 0.2 km(3) a(-1). The calculated mean water depth at the terminus is 190 m. This calving rate is higher than at grounded temperate glaciers calving in fresh water, but is nevertheless almost an order of magnitude less than calving rates at both grounded and floating tidewater glaciers. Article in Journal/Newspaper glacier glaciers Journal of Glaciology Tidewater Alaska University of St Andrews: Research Portal Hielo ENVELOPE(-58.133,-58.133,-62.083,-62.083) New Zealand Patagonia |
institution |
Open Polar |
collection |
University of St Andrews: Research Portal |
op_collection_id |
ftunstandrewcris |
language |
English |
topic |
INTERFEROMETRIC RADAR OBSERVATIONS COOK NATIONAL-PARK SOUTHERN PATAGONIA NEW-ZEALAND TIDEWATER GLACIER COLUMBIA GLACIER SAN-RAFAEL ICEFIELD ALASKA ICE |
spellingShingle |
INTERFEROMETRIC RADAR OBSERVATIONS COOK NATIONAL-PARK SOUTHERN PATAGONIA NEW-ZEALAND TIDEWATER GLACIER COLUMBIA GLACIER SAN-RAFAEL ICEFIELD ALASKA ICE Warren, Charles Raymond Benn, DI Winchester, V Harrison, S Buoyancy-driven lacustrine calving, Glaciar Nef, Chilean Patagonia |
topic_facet |
INTERFEROMETRIC RADAR OBSERVATIONS COOK NATIONAL-PARK SOUTHERN PATAGONIA NEW-ZEALAND TIDEWATER GLACIER COLUMBIA GLACIER SAN-RAFAEL ICEFIELD ALASKA ICE |
description |
Glaciar Nef, a 164 km(2) eastern outlet of Hielo Patagonico Norte (the northern Patagonia icefield), terminates in a proglacial lake that has formed in conjunction with 20th-century glacier retreat. The terminus is inferred to be transiently afloat. A hinge-calving mechanism is proposed in which buoyant forces impose a torque on the glacier tongue, resulting in the release of coherent sections of the glacier tongue as "tabular" icebergs. A simple model shows how torque and tensile stress reach a maximum at the up-glacier limit of the buoyant zone, and that glacier thinning causes this point to migrate up-glacier Empirical evidence supporting this model includes elevated thermo-erosional notches less than or equal to 6.5 in above lake level, and the ubiquitous presence since 1975 of "tabular" icebergs with surface areas < 0.3 km(2). Flow speeds of 1.2-1.3 m d(-1) were measured near the terminus in February 1998. Extrapolations from these short-term data yield a calving rate of 785-835 m a(-1) and a calving flux of 232 x 10(6) m(3) a(-1) or 0.2 km(3) a(-1). The calculated mean water depth at the terminus is 190 m. This calving rate is higher than at grounded temperate glaciers calving in fresh water, but is nevertheless almost an order of magnitude less than calving rates at both grounded and floating tidewater glaciers. |
format |
Article in Journal/Newspaper |
author |
Warren, Charles Raymond Benn, DI Winchester, V Harrison, S |
author_facet |
Warren, Charles Raymond Benn, DI Winchester, V Harrison, S |
author_sort |
Warren, Charles Raymond |
title |
Buoyancy-driven lacustrine calving, Glaciar Nef, Chilean Patagonia |
title_short |
Buoyancy-driven lacustrine calving, Glaciar Nef, Chilean Patagonia |
title_full |
Buoyancy-driven lacustrine calving, Glaciar Nef, Chilean Patagonia |
title_fullStr |
Buoyancy-driven lacustrine calving, Glaciar Nef, Chilean Patagonia |
title_full_unstemmed |
Buoyancy-driven lacustrine calving, Glaciar Nef, Chilean Patagonia |
title_sort |
buoyancy-driven lacustrine calving, glaciar nef, chilean patagonia |
publishDate |
2001 |
url |
https://risweb.st-andrews.ac.uk/portal/en/researchoutput/buoyancydriven-lacustrine-calving-glaciar-nef-chilean-patagonia(8eeaced2-bf4c-43f2-bb5a-4bf37d8d8263).html http://www.scopus.com/inward/record.url?scp=0034857168&partnerID=8YFLogxK |
long_lat |
ENVELOPE(-58.133,-58.133,-62.083,-62.083) |
geographic |
Hielo New Zealand Patagonia |
geographic_facet |
Hielo New Zealand Patagonia |
genre |
glacier glaciers Journal of Glaciology Tidewater Alaska |
genre_facet |
glacier glaciers Journal of Glaciology Tidewater Alaska |
op_source |
Warren , C R , Benn , DI , Winchester , V & Harrison , S 2001 , ' Buoyancy-driven lacustrine calving, Glaciar Nef, Chilean Patagonia ' , Journal of Glaciology , vol. 47 , no. 156 , pp. 135-146 . |
op_rights |
info:eu-repo/semantics/restrictedAccess |
_version_ |
1766008370317230080 |