Importance of basal processes in simulations of a surging Svalbard outlet glacier
The outlet glacier of Basin 3 (B3) of Austfonna ice cap, Svalbard, is one of the fastest outlet glaciers in Svalbard, and shows dramatic changes since 1995. In addition to previously observed seasonal summer speed-up associated with the melt season, the winter speed of B3 has accelerated approximate...
Published in: | The Cryosphere |
---|---|
Main Authors: | , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Uppsala universitet, Luft-, vatten- och landskapslära
2014
|
Subjects: | |
Online Access: | http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-235210 https://doi.org/10.5194/tc-8-1393-2014 |
id |
ftuppsalauniv:oai:DiVA.org:uu-235210 |
---|---|
record_format |
openpolar |
spelling |
ftuppsalauniv:oai:DiVA.org:uu-235210 2023-05-15T15:33:56+02:00 Importance of basal processes in simulations of a surging Svalbard outlet glacier Gladstone, R. Schafer, M. Zwinger, T. Gong, Y. Strozzi, T. Mottram, R. Boberg, F. Moore, John C. 2014 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-235210 https://doi.org/10.5194/tc-8-1393-2014 eng eng Uppsala universitet, Luft-, vatten- och landskapslära The Cryosphere, 1994-0416, 2014, 8:4, s. 1393-1405 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-235210 doi:10.5194/tc-8-1393-2014 ISI:000341622700019 info:eu-repo/semantics/openAccess Geology Geologi Article in journal info:eu-repo/semantics/article text 2014 ftuppsalauniv https://doi.org/10.5194/tc-8-1393-2014 2023-02-23T21:52:07Z The outlet glacier of Basin 3 (B3) of Austfonna ice cap, Svalbard, is one of the fastest outlet glaciers in Svalbard, and shows dramatic changes since 1995. In addition to previously observed seasonal summer speed-up associated with the melt season, the winter speed of B3 has accelerated approximately fivefold since 1995. We use the Elmer/Ice full-Stokes model for ice dynamics to infer spatial distributions of basal drag for the winter seasons of 1995, 2008 and 2011. This "inverse" method is based on minimising discrepancy between modelled and observed surface velocities, using satellite remotely sensed velocity fields. We generate steady-state temperature distributions for 1995 and 2011. Frictional heating caused by basal sliding contributes significantly to basal temperatures of the B3 outlet glacier, with heat advection (a longer-timescale process than frictional heating) also being important in the steady state. We present a sensitivity experiment consisting of transient simulations under present-day forcing to demonstrate that using a temporally fixed basal drag field obtained through inversion can lead to thickness change errors of the order of 2m year(-1). Hence it is essential to incorporate the evolution of basal processes in future projections of the evolution of B3. Informed by a combination of our inverse method results and previous studies, we hypothesise a system of processes and feedbacks involving till deformation and basal hydrology to explain both the seasonal accelerations (short residence time pooling of meltwater at the ice-till interface) and the ongoing interannual speed-up (gradual penetration of water into the till, reducing till strength). Article in Journal/Newspaper Austfonna glacier Ice cap Svalbard The Cryosphere Uppsala University: Publications (DiVA) Austfonna ENVELOPE(24.559,24.559,79.835,79.835) Svalbard The Cryosphere 8 4 1393 1405 |
institution |
Open Polar |
collection |
Uppsala University: Publications (DiVA) |
op_collection_id |
ftuppsalauniv |
language |
English |
topic |
Geology Geologi |
spellingShingle |
Geology Geologi Gladstone, R. Schafer, M. Zwinger, T. Gong, Y. Strozzi, T. Mottram, R. Boberg, F. Moore, John C. Importance of basal processes in simulations of a surging Svalbard outlet glacier |
topic_facet |
Geology Geologi |
description |
The outlet glacier of Basin 3 (B3) of Austfonna ice cap, Svalbard, is one of the fastest outlet glaciers in Svalbard, and shows dramatic changes since 1995. In addition to previously observed seasonal summer speed-up associated with the melt season, the winter speed of B3 has accelerated approximately fivefold since 1995. We use the Elmer/Ice full-Stokes model for ice dynamics to infer spatial distributions of basal drag for the winter seasons of 1995, 2008 and 2011. This "inverse" method is based on minimising discrepancy between modelled and observed surface velocities, using satellite remotely sensed velocity fields. We generate steady-state temperature distributions for 1995 and 2011. Frictional heating caused by basal sliding contributes significantly to basal temperatures of the B3 outlet glacier, with heat advection (a longer-timescale process than frictional heating) also being important in the steady state. We present a sensitivity experiment consisting of transient simulations under present-day forcing to demonstrate that using a temporally fixed basal drag field obtained through inversion can lead to thickness change errors of the order of 2m year(-1). Hence it is essential to incorporate the evolution of basal processes in future projections of the evolution of B3. Informed by a combination of our inverse method results and previous studies, we hypothesise a system of processes and feedbacks involving till deformation and basal hydrology to explain both the seasonal accelerations (short residence time pooling of meltwater at the ice-till interface) and the ongoing interannual speed-up (gradual penetration of water into the till, reducing till strength). |
format |
Article in Journal/Newspaper |
author |
Gladstone, R. Schafer, M. Zwinger, T. Gong, Y. Strozzi, T. Mottram, R. Boberg, F. Moore, John C. |
author_facet |
Gladstone, R. Schafer, M. Zwinger, T. Gong, Y. Strozzi, T. Mottram, R. Boberg, F. Moore, John C. |
author_sort |
Gladstone, R. |
title |
Importance of basal processes in simulations of a surging Svalbard outlet glacier |
title_short |
Importance of basal processes in simulations of a surging Svalbard outlet glacier |
title_full |
Importance of basal processes in simulations of a surging Svalbard outlet glacier |
title_fullStr |
Importance of basal processes in simulations of a surging Svalbard outlet glacier |
title_full_unstemmed |
Importance of basal processes in simulations of a surging Svalbard outlet glacier |
title_sort |
importance of basal processes in simulations of a surging svalbard outlet glacier |
publisher |
Uppsala universitet, Luft-, vatten- och landskapslära |
publishDate |
2014 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-235210 https://doi.org/10.5194/tc-8-1393-2014 |
long_lat |
ENVELOPE(24.559,24.559,79.835,79.835) |
geographic |
Austfonna Svalbard |
geographic_facet |
Austfonna Svalbard |
genre |
Austfonna glacier Ice cap Svalbard The Cryosphere |
genre_facet |
Austfonna glacier Ice cap Svalbard The Cryosphere |
op_relation |
The Cryosphere, 1994-0416, 2014, 8:4, s. 1393-1405 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-235210 doi:10.5194/tc-8-1393-2014 ISI:000341622700019 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/tc-8-1393-2014 |
container_title |
The Cryosphere |
container_volume |
8 |
container_issue |
4 |
container_start_page |
1393 |
op_container_end_page |
1405 |
_version_ |
1766364517793529856 |