Upstream flow effects revealed in the EastGRIP ice core using Monte Carlo inversion of a two-dimensional ice-flow model
The Northeast Greenland Ice Stream (NEGIS) is the largest active ice stream on the Greenland Ice Sheet (GrIS) and a crucial contributor to the ice-sheet mass balance. To investigate the ice-stream dynamics and to gain information about the past climate, a deep ice core is drilled in the upstream par...
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Copernicus Publications
2021
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ftdoajarticles:oai:doaj.org/article:27cf60d4687f4ad8be86d0ebac2b4f9f 2023-05-15T16:03:55+02:00 Upstream flow effects revealed in the EastGRIP ice core using Monte Carlo inversion of a two-dimensional ice-flow model T. A. Gerber C. S. Hvidberg S. O. Rasmussen S. Franke G. Sinnl A. Grinsted D. Jansen D. Dahl-Jensen 2021-08-01T00:00:00Z https://doi.org/10.5194/tc-15-3655-2021 https://doaj.org/article/27cf60d4687f4ad8be86d0ebac2b4f9f EN eng Copernicus Publications https://tc.copernicus.org/articles/15/3655/2021/tc-15-3655-2021.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-15-3655-2021 1994-0416 1994-0424 https://doaj.org/article/27cf60d4687f4ad8be86d0ebac2b4f9f The Cryosphere, Vol 15, Pp 3655-3679 (2021) Environmental sciences GE1-350 Geology QE1-996.5 article 2021 ftdoajarticles https://doi.org/10.5194/tc-15-3655-2021 2022-12-31T06:36:04Z The Northeast Greenland Ice Stream (NEGIS) is the largest active ice stream on the Greenland Ice Sheet (GrIS) and a crucial contributor to the ice-sheet mass balance. To investigate the ice-stream dynamics and to gain information about the past climate, a deep ice core is drilled in the upstream part of the NEGIS, termed the East Greenland Ice-core Project (EastGRIP). Upstream flow can introduce climatic bias into ice cores through the advection of ice deposited under different conditions further upstream. This is particularly true for EastGRIP due to its location inside an ice stream on the eastern flank of the GrIS. Understanding and ultimately correcting for such effects requires information on the atmospheric conditions at the time and location of snow deposition. We use a two-dimensional Dansgaard–Johnsen model to simulate ice flow along three approximated flow lines between the summit of the ice sheet (GRIP) and EastGRIP. Isochrones are traced in radio-echo-sounding images along these flow lines and dated with the GRIP and EastGRIP ice-core chronologies. The observed depth–age relationship constrains the Monte Carlo method which is used to determine unknown model parameters. We calculate backward-in-time particle trajectories to determine the source location of ice found in the EastGRIP ice core and present estimates of surface elevation and past accumulation rates at the deposition site. Our results indicate that increased snow accumulation with increasing upstream distance is predominantly responsible for the constant annual layer thicknesses observed in the upper part of the ice column at EastGRIP, and the inverted model parameters suggest that basal melting and sliding are important factors determining ice flow in the NEGIS. The results of this study form a basis for applying upstream corrections to a variety of ice-core measurements, and the inverted model parameters are useful constraints for more sophisticated modelling approaches in the future. Article in Journal/Newspaper East Greenland East Greenland Ice-core Project Greenland Greenland ice core Greenland Ice core Project GRIP ice core Ice Sheet The Cryosphere Directory of Open Access Journals: DOAJ Articles Greenland The Cryosphere 15 8 3655 3679 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 T. A. Gerber C. S. Hvidberg S. O. Rasmussen S. Franke G. Sinnl A. Grinsted D. Jansen D. Dahl-Jensen Upstream flow effects revealed in the EastGRIP ice core using Monte Carlo inversion of a two-dimensional ice-flow model |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
The Northeast Greenland Ice Stream (NEGIS) is the largest active ice stream on the Greenland Ice Sheet (GrIS) and a crucial contributor to the ice-sheet mass balance. To investigate the ice-stream dynamics and to gain information about the past climate, a deep ice core is drilled in the upstream part of the NEGIS, termed the East Greenland Ice-core Project (EastGRIP). Upstream flow can introduce climatic bias into ice cores through the advection of ice deposited under different conditions further upstream. This is particularly true for EastGRIP due to its location inside an ice stream on the eastern flank of the GrIS. Understanding and ultimately correcting for such effects requires information on the atmospheric conditions at the time and location of snow deposition. We use a two-dimensional Dansgaard–Johnsen model to simulate ice flow along three approximated flow lines between the summit of the ice sheet (GRIP) and EastGRIP. Isochrones are traced in radio-echo-sounding images along these flow lines and dated with the GRIP and EastGRIP ice-core chronologies. The observed depth–age relationship constrains the Monte Carlo method which is used to determine unknown model parameters. We calculate backward-in-time particle trajectories to determine the source location of ice found in the EastGRIP ice core and present estimates of surface elevation and past accumulation rates at the deposition site. Our results indicate that increased snow accumulation with increasing upstream distance is predominantly responsible for the constant annual layer thicknesses observed in the upper part of the ice column at EastGRIP, and the inverted model parameters suggest that basal melting and sliding are important factors determining ice flow in the NEGIS. The results of this study form a basis for applying upstream corrections to a variety of ice-core measurements, and the inverted model parameters are useful constraints for more sophisticated modelling approaches in the future. |
format |
Article in Journal/Newspaper |
author |
T. A. Gerber C. S. Hvidberg S. O. Rasmussen S. Franke G. Sinnl A. Grinsted D. Jansen D. Dahl-Jensen |
author_facet |
T. A. Gerber C. S. Hvidberg S. O. Rasmussen S. Franke G. Sinnl A. Grinsted D. Jansen D. Dahl-Jensen |
author_sort |
T. A. Gerber |
title |
Upstream flow effects revealed in the EastGRIP ice core using Monte Carlo inversion of a two-dimensional ice-flow model |
title_short |
Upstream flow effects revealed in the EastGRIP ice core using Monte Carlo inversion of a two-dimensional ice-flow model |
title_full |
Upstream flow effects revealed in the EastGRIP ice core using Monte Carlo inversion of a two-dimensional ice-flow model |
title_fullStr |
Upstream flow effects revealed in the EastGRIP ice core using Monte Carlo inversion of a two-dimensional ice-flow model |
title_full_unstemmed |
Upstream flow effects revealed in the EastGRIP ice core using Monte Carlo inversion of a two-dimensional ice-flow model |
title_sort |
upstream flow effects revealed in the eastgrip ice core using monte carlo inversion of a two-dimensional ice-flow model |
publisher |
Copernicus Publications |
publishDate |
2021 |
url |
https://doi.org/10.5194/tc-15-3655-2021 https://doaj.org/article/27cf60d4687f4ad8be86d0ebac2b4f9f |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
East Greenland East Greenland Ice-core Project Greenland Greenland ice core Greenland Ice core Project GRIP ice core Ice Sheet The Cryosphere |
genre_facet |
East Greenland East Greenland Ice-core Project Greenland Greenland ice core Greenland Ice core Project GRIP ice core Ice Sheet The Cryosphere |
op_source |
The Cryosphere, Vol 15, Pp 3655-3679 (2021) |
op_relation |
https://tc.copernicus.org/articles/15/3655/2021/tc-15-3655-2021.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-15-3655-2021 1994-0416 1994-0424 https://doaj.org/article/27cf60d4687f4ad8be86d0ebac2b4f9f |
op_doi |
https://doi.org/10.5194/tc-15-3655-2021 |
container_title |
The Cryosphere |
container_volume |
15 |
container_issue |
8 |
container_start_page |
3655 |
op_container_end_page |
3679 |
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1766399602673582080 |