Impact of External Forcing on Glacier Dynamics at Jakobshavn Isbræ during 1840-2012
Greenland's main outlet glaciers have more than doubled their contribution to global sea-level rise over the past decade through acceleration of ice discharge. One of the triggering mechanisms is a reduction in resistance (buttressing) at the marine based glacier front (i.e. through reduced thi...
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ftdtupubl:oai:pure.atira.dk:publications/80639321-beeb-4aa5-9909-46d005b7f25b 2024-09-15T18:07:42+00:00 Impact of External Forcing on Glacier Dynamics at Jakobshavn Isbræ during 1840-2012 Muresan, Ioana Stefania Khan, Shfaqat Abbas Aschwanden, Andy Khroulev, Constantine Bjørk, Anders A. Box, Jason E. 2014 application/pdf https://orbit.dtu.dk/en/publications/80639321-beeb-4aa5-9909-46d005b7f25b https://backend.orbit.dtu.dk/ws/files/126583192/Impact_of_External_Forcing_on_Glacier_Dynamics_at_Jakobshavn_Isbr_during_1840_2012.pdf eng eng https://orbit.dtu.dk/en/publications/80639321-beeb-4aa5-9909-46d005b7f25b info:eu-repo/semantics/openAccess Muresan , I S , Khan , S A , Aschwanden , A , Khroulev , C , Bjørk , A A & Box , J E 2014 , ' Impact of External Forcing on Glacier Dynamics at Jakobshavn Isbræ during 1840-2012 ' , 2014 AGU Fall Meeting , San Francisco, CA , United States , 15/12/2014 - 19/12/2014 . /dk/atira/pure/sustainabledevelopmentgoals/life_below_water name=SDG 14 - Life Below Water conferenceObject 2014 ftdtupubl 2024-07-01T23:52:53Z Greenland's main outlet glaciers have more than doubled their contribution to global sea-level rise over the past decade through acceleration of ice discharge. One of the triggering mechanisms is a reduction in resistance (buttressing) at the marine based glacier front (i.e. through reduced thickness or retreat of the floating tongue of a glacier) caused by enhanced calving or a longer-term thinning due to a mass deficit of the ice sheet. Recent findings indicate the reduced buttressing at the marine terminus is responsible for the recent dynamic changes observed in Greenland, but the controlling processes and triggering mechanisms are still unclear. Furthermore, our current understanding is almost entirely based on observations from a short-term record spanning only from a year to a decade, and is characterized by short-term fluctuations and therefore not representative for longer-term trends of several decade time scales. Here, we study the mechanisms controlling dynamic changes at the terminus of Jakobshavn Isbræ over a period of 172 years. The recent glacier acceleration began in late 1990s but there is evidence for glacier retreat of comparable magnitude in 1930s, when a similarly warm period occurred. To control the acceleration and retreat based on observed front positions during 1840-2012, we use an ocean model modifier that implements forcing at the ocean boundary using melange back pressure offsets. The mean temperature anomaly in west Greenland, the North Atlantic oscillation (NAO) winter index and the Atlantic multidecadal oscillation (AMO) index anomalies for the period 1900-2012 sustain our modelling results. The modelled surface elevation changes near the front are considered and compared with observed surface elevation changes for the period 1880-2012. Furthermore, the modelled mass loss signal between 1997-2012 is validated based on ice mass change observations which we estimate using altimeter surveys from NASA's ATM flights during 1997-2012 supplemented with high-resolution Ice, Cloud and land ... Conference Object glacier Greenland Ice Sheet Jakobshavn Jakobshavn isbræ North Atlantic North Atlantic oscillation Technical University of Denmark: DTU Orbit |
institution |
Open Polar |
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Technical University of Denmark: DTU Orbit |
op_collection_id |
ftdtupubl |
language |
English |
topic |
/dk/atira/pure/sustainabledevelopmentgoals/life_below_water name=SDG 14 - Life Below Water |
spellingShingle |
/dk/atira/pure/sustainabledevelopmentgoals/life_below_water name=SDG 14 - Life Below Water Muresan, Ioana Stefania Khan, Shfaqat Abbas Aschwanden, Andy Khroulev, Constantine Bjørk, Anders A. Box, Jason E. Impact of External Forcing on Glacier Dynamics at Jakobshavn Isbræ during 1840-2012 |
topic_facet |
/dk/atira/pure/sustainabledevelopmentgoals/life_below_water name=SDG 14 - Life Below Water |
description |
Greenland's main outlet glaciers have more than doubled their contribution to global sea-level rise over the past decade through acceleration of ice discharge. One of the triggering mechanisms is a reduction in resistance (buttressing) at the marine based glacier front (i.e. through reduced thickness or retreat of the floating tongue of a glacier) caused by enhanced calving or a longer-term thinning due to a mass deficit of the ice sheet. Recent findings indicate the reduced buttressing at the marine terminus is responsible for the recent dynamic changes observed in Greenland, but the controlling processes and triggering mechanisms are still unclear. Furthermore, our current understanding is almost entirely based on observations from a short-term record spanning only from a year to a decade, and is characterized by short-term fluctuations and therefore not representative for longer-term trends of several decade time scales. Here, we study the mechanisms controlling dynamic changes at the terminus of Jakobshavn Isbræ over a period of 172 years. The recent glacier acceleration began in late 1990s but there is evidence for glacier retreat of comparable magnitude in 1930s, when a similarly warm period occurred. To control the acceleration and retreat based on observed front positions during 1840-2012, we use an ocean model modifier that implements forcing at the ocean boundary using melange back pressure offsets. The mean temperature anomaly in west Greenland, the North Atlantic oscillation (NAO) winter index and the Atlantic multidecadal oscillation (AMO) index anomalies for the period 1900-2012 sustain our modelling results. The modelled surface elevation changes near the front are considered and compared with observed surface elevation changes for the period 1880-2012. Furthermore, the modelled mass loss signal between 1997-2012 is validated based on ice mass change observations which we estimate using altimeter surveys from NASA's ATM flights during 1997-2012 supplemented with high-resolution Ice, Cloud and land ... |
format |
Conference Object |
author |
Muresan, Ioana Stefania Khan, Shfaqat Abbas Aschwanden, Andy Khroulev, Constantine Bjørk, Anders A. Box, Jason E. |
author_facet |
Muresan, Ioana Stefania Khan, Shfaqat Abbas Aschwanden, Andy Khroulev, Constantine Bjørk, Anders A. Box, Jason E. |
author_sort |
Muresan, Ioana Stefania |
title |
Impact of External Forcing on Glacier Dynamics at Jakobshavn Isbræ during 1840-2012 |
title_short |
Impact of External Forcing on Glacier Dynamics at Jakobshavn Isbræ during 1840-2012 |
title_full |
Impact of External Forcing on Glacier Dynamics at Jakobshavn Isbræ during 1840-2012 |
title_fullStr |
Impact of External Forcing on Glacier Dynamics at Jakobshavn Isbræ during 1840-2012 |
title_full_unstemmed |
Impact of External Forcing on Glacier Dynamics at Jakobshavn Isbræ during 1840-2012 |
title_sort |
impact of external forcing on glacier dynamics at jakobshavn isbræ during 1840-2012 |
publishDate |
2014 |
url |
https://orbit.dtu.dk/en/publications/80639321-beeb-4aa5-9909-46d005b7f25b https://backend.orbit.dtu.dk/ws/files/126583192/Impact_of_External_Forcing_on_Glacier_Dynamics_at_Jakobshavn_Isbr_during_1840_2012.pdf |
genre |
glacier Greenland Ice Sheet Jakobshavn Jakobshavn isbræ North Atlantic North Atlantic oscillation |
genre_facet |
glacier Greenland Ice Sheet Jakobshavn Jakobshavn isbræ North Atlantic North Atlantic oscillation |
op_source |
Muresan , I S , Khan , S A , Aschwanden , A , Khroulev , C , Bjørk , A A & Box , J E 2014 , ' Impact of External Forcing on Glacier Dynamics at Jakobshavn Isbræ during 1840-2012 ' , 2014 AGU Fall Meeting , San Francisco, CA , United States , 15/12/2014 - 19/12/2014 . |
op_relation |
https://orbit.dtu.dk/en/publications/80639321-beeb-4aa5-9909-46d005b7f25b |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1810445080970919936 |