Outlet glacier response to forcing over hourly to interannual timescales, Jakobshavn Isbræ, Greenland
The loss of the floating ice tongue on Jakobshavn Isbræ, Greenland, in the early 2000s has been concurrent with a pattern of thinning, retreat and acceleration leading to enhanced contribution to global sea level. The loss of the floating ice tongue on Jakobshavn Isbræ, Greenland, in the early 2000s...
Published in: | Journal of Glaciology |
---|---|
Main Authors: | , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
International Glaciological Society
2012
|
Subjects: | |
Online Access: | http://hdl.handle.net/11122/11057 |
id |
ftunivalaska:oai:scholarworks.alaska.edu:11122/11057 |
---|---|
record_format |
openpolar |
spelling |
ftunivalaska:oai:scholarworks.alaska.edu:11122/11057 2023-05-15T16:21:03+02:00 Outlet glacier response to forcing over hourly to interannual timescales, Jakobshavn Isbræ, Greenland Outlet glacier response to forcing on short timescales Podrasky, David Truffer, Martin Fahnestock, Mark Amundson, Jason M. Cassoto, Ryan Joughin, Ian 2012-09-07 http://hdl.handle.net/11122/11057 en_US eng International Glaciological Society Podrasky, D., M. Truffer, M. Fahnestock, J. M. Amundson, R. Cassotto, and I. Joughin (2012), Outlet glacier response to forcing over hourly to interannual timescales, Jakobshavn Isbræ, Greenland, J. Glaciol., 58(212), 1212– 1226, doi:10.3189/2012JoG12J065. http://hdl.handle.net/11122/11057 Journal of Glaciology glaciers outlet glaciers Greenland floating ice tongue terminus terminus position interannual timescales supraglacial lakes Article 2012 ftunivalaska https://doi.org/10.3189/2012JoG12J065 2023-02-23T21:37:36Z The loss of the floating ice tongue on Jakobshavn Isbræ, Greenland, in the early 2000s has been concurrent with a pattern of thinning, retreat and acceleration leading to enhanced contribution to global sea level. The loss of the floating ice tongue on Jakobshavn Isbræ, Greenland, in the early 2000s has been concurrent with a pattern of thinning, retreat and acceleration leading to enhanced contribution to global sea level. These changes on decadal timescales have been well documented. Here we identify how the glacier responds to forcings on shorter timescales, such as from variations in surface melt, the drainage of supraglacial lakes and seasonal fluctuations in terminus position. Ice motion and surface melt were monitored intermittently from 2006 to 2008. Dual-frequency GPS were deployed 20–50 km upstream of the terminus along the glacier center line. Gaps in surface melt measurements were filled using a temperature-index model of ablation driven by surface air temperatures recorded during the same time period. Our results corroborate the premise that the primary factors controlling speeds on Jakobshavn Isbræ are terminus position and geometry. We also observe that surface speeds demonstrate a complex relationship with meltwater input: on diurnal timescales, velocities closely match changes in water input; however, on seasonal timescales a longer, more intense melt season was observed to effectively reduce the overall ice flow of the glacier for the whole year. Support for this project was provided by NASA’s Cryospheric Sciences Program (NNG06GB49G). Logistical support was provided by CH2M Hill Polar Field Services and instrument support was provided by the University Navstar Consortium (UNAVCO). We thank J. Brown, M. Lu ̈thi and R.J. Motyka for help in the field, and S. Herreid for his GIS wizardry. Helpful discussions with A. Aschwanden greatly improved the clarity of the figures. We thank two anonymous reviewers for comments which greatly improved the clarity of the manuscript. Yes Article in Journal/Newspaper glacier Greenland Jakobshavn Jakobshavn isbræ Journal of Glaciology University of Alaska: ScholarWorks@UA Greenland Jakobshavn Isbræ ENVELOPE(-49.917,-49.917,69.167,69.167) Journal of Glaciology 58 212 1212 1226 |
institution |
Open Polar |
collection |
University of Alaska: ScholarWorks@UA |
op_collection_id |
ftunivalaska |
language |
English |
topic |
glaciers outlet glaciers Greenland floating ice tongue terminus terminus position interannual timescales supraglacial lakes |
spellingShingle |
glaciers outlet glaciers Greenland floating ice tongue terminus terminus position interannual timescales supraglacial lakes Podrasky, David Truffer, Martin Fahnestock, Mark Amundson, Jason M. Cassoto, Ryan Joughin, Ian Outlet glacier response to forcing over hourly to interannual timescales, Jakobshavn Isbræ, Greenland |
topic_facet |
glaciers outlet glaciers Greenland floating ice tongue terminus terminus position interannual timescales supraglacial lakes |
description |
The loss of the floating ice tongue on Jakobshavn Isbræ, Greenland, in the early 2000s has been concurrent with a pattern of thinning, retreat and acceleration leading to enhanced contribution to global sea level. The loss of the floating ice tongue on Jakobshavn Isbræ, Greenland, in the early 2000s has been concurrent with a pattern of thinning, retreat and acceleration leading to enhanced contribution to global sea level. These changes on decadal timescales have been well documented. Here we identify how the glacier responds to forcings on shorter timescales, such as from variations in surface melt, the drainage of supraglacial lakes and seasonal fluctuations in terminus position. Ice motion and surface melt were monitored intermittently from 2006 to 2008. Dual-frequency GPS were deployed 20–50 km upstream of the terminus along the glacier center line. Gaps in surface melt measurements were filled using a temperature-index model of ablation driven by surface air temperatures recorded during the same time period. Our results corroborate the premise that the primary factors controlling speeds on Jakobshavn Isbræ are terminus position and geometry. We also observe that surface speeds demonstrate a complex relationship with meltwater input: on diurnal timescales, velocities closely match changes in water input; however, on seasonal timescales a longer, more intense melt season was observed to effectively reduce the overall ice flow of the glacier for the whole year. Support for this project was provided by NASA’s Cryospheric Sciences Program (NNG06GB49G). Logistical support was provided by CH2M Hill Polar Field Services and instrument support was provided by the University Navstar Consortium (UNAVCO). We thank J. Brown, M. Lu ̈thi and R.J. Motyka for help in the field, and S. Herreid for his GIS wizardry. Helpful discussions with A. Aschwanden greatly improved the clarity of the figures. We thank two anonymous reviewers for comments which greatly improved the clarity of the manuscript. Yes |
format |
Article in Journal/Newspaper |
author |
Podrasky, David Truffer, Martin Fahnestock, Mark Amundson, Jason M. Cassoto, Ryan Joughin, Ian |
author_facet |
Podrasky, David Truffer, Martin Fahnestock, Mark Amundson, Jason M. Cassoto, Ryan Joughin, Ian |
author_sort |
Podrasky, David |
title |
Outlet glacier response to forcing over hourly to interannual timescales, Jakobshavn Isbræ, Greenland |
title_short |
Outlet glacier response to forcing over hourly to interannual timescales, Jakobshavn Isbræ, Greenland |
title_full |
Outlet glacier response to forcing over hourly to interannual timescales, Jakobshavn Isbræ, Greenland |
title_fullStr |
Outlet glacier response to forcing over hourly to interannual timescales, Jakobshavn Isbræ, Greenland |
title_full_unstemmed |
Outlet glacier response to forcing over hourly to interannual timescales, Jakobshavn Isbræ, Greenland |
title_sort |
outlet glacier response to forcing over hourly to interannual timescales, jakobshavn isbræ, greenland |
publisher |
International Glaciological Society |
publishDate |
2012 |
url |
http://hdl.handle.net/11122/11057 |
long_lat |
ENVELOPE(-49.917,-49.917,69.167,69.167) |
geographic |
Greenland Jakobshavn Isbræ |
geographic_facet |
Greenland Jakobshavn Isbræ |
genre |
glacier Greenland Jakobshavn Jakobshavn isbræ Journal of Glaciology |
genre_facet |
glacier Greenland Jakobshavn Jakobshavn isbræ Journal of Glaciology |
op_relation |
Podrasky, D., M. Truffer, M. Fahnestock, J. M. Amundson, R. Cassotto, and I. Joughin (2012), Outlet glacier response to forcing over hourly to interannual timescales, Jakobshavn Isbræ, Greenland, J. Glaciol., 58(212), 1212– 1226, doi:10.3189/2012JoG12J065. http://hdl.handle.net/11122/11057 Journal of Glaciology |
op_doi |
https://doi.org/10.3189/2012JoG12J065 |
container_title |
Journal of Glaciology |
container_volume |
58 |
container_issue |
212 |
container_start_page |
1212 |
op_container_end_page |
1226 |
_version_ |
1766009071681404928 |