Simulating the Greenland Ice Sheet Surface Mass Balance using an Earth System Model
Observational evidence shows that the Greenland Ice Sheet (GrIS) is currently losing mass, and that this mass loss is accelerating. In this dissertation, we look at the representation of GrIS climate in the Community Earth System Model (CESM), in which ice sheet interactions with other parts of the...
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Utrecht University
2020
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Online Access: | https://dspace.library.uu.nl/handle/1874/400695 |
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ftunivutrecht:oai:dspace.library.uu.nl:1874/400695 2023-07-23T04:19:32+02:00 Simulating the Greenland Ice Sheet Surface Mass Balance using an Earth System Model van Kampenhout, Leonardus Broeke, M.R. van den Lenaerts, J.T.M. 2020-09-07 image/pdf https://dspace.library.uu.nl/handle/1874/400695 en eng Utrecht University https://dspace.library.uu.nl/handle/1874/400695 info:eu-repo/semantics/OpenAccess Groenland klimaatmodel zeespiegelstijging ijskap modelontwikkeling Dissertation 2020 ftunivutrecht 2023-07-02T03:11:19Z Observational evidence shows that the Greenland Ice Sheet (GrIS) is currently losing mass, and that this mass loss is accelerating. In this dissertation, we look at the representation of GrIS climate in the Community Earth System Model (CESM), in which ice sheet interactions with other parts of the climate system can be consistently resolved. The central metric is the surface mass balance (SMB), as a realistic representation of SMB is a prerequisite for gaining confidence in ice sheet mass loss projections. Our first study investigates the representation of polar snow and firn in CESM. We introduce new parametrizations for fresh snow density and snow compaction and increase the number of snow layers in the model. These model improvements largely resolve issues identified by previous work, including an insufficient refreezing capacity and spurious subsurface melt rates. Our second study concerns spatial resolution. Previous work on regional models has indicated that ~20 km resolution is needed to resolve steep SMB gradients near the GrIS margins, whereas CESM has a nominal resolution of 1° (~100 km). We apply, for the first time, regional grid refinement (55 and 28 km) to the Greenland region using Variable Resolution CESM. We find that although precipitation is greatly improved with enhanced resolution, surface runoff is not. Our third study evaluates the present-day GrIS climate in CESM version 2 (CESM2). We find that CESM2 overestimates the net radiative input at the surface in summer, primarily driven by a low biased albedo, which is compensating for a lack in sensible turbulent heat flux. GrIS ablation zones do not always overlap with that in RACMO2, but the difference in total ablation area is small (-11%). Integrated amounts of SMB components melt, refreezing and runoff are all bracketed by RACMO2 equivalents at the resolutions 11 km (native) and 1 km (statistically down- scaled), indicating a good performance. Our last study explores the future timing of GrIS SMB turning from positive to negative. If such ... Doctoral or Postdoctoral Thesis Greenland Groenland Ice Sheet Utrecht University Repository Greenland |
institution |
Open Polar |
collection |
Utrecht University Repository |
op_collection_id |
ftunivutrecht |
language |
English |
topic |
Groenland klimaatmodel zeespiegelstijging ijskap modelontwikkeling |
spellingShingle |
Groenland klimaatmodel zeespiegelstijging ijskap modelontwikkeling van Kampenhout, Leonardus Simulating the Greenland Ice Sheet Surface Mass Balance using an Earth System Model |
topic_facet |
Groenland klimaatmodel zeespiegelstijging ijskap modelontwikkeling |
description |
Observational evidence shows that the Greenland Ice Sheet (GrIS) is currently losing mass, and that this mass loss is accelerating. In this dissertation, we look at the representation of GrIS climate in the Community Earth System Model (CESM), in which ice sheet interactions with other parts of the climate system can be consistently resolved. The central metric is the surface mass balance (SMB), as a realistic representation of SMB is a prerequisite for gaining confidence in ice sheet mass loss projections. Our first study investigates the representation of polar snow and firn in CESM. We introduce new parametrizations for fresh snow density and snow compaction and increase the number of snow layers in the model. These model improvements largely resolve issues identified by previous work, including an insufficient refreezing capacity and spurious subsurface melt rates. Our second study concerns spatial resolution. Previous work on regional models has indicated that ~20 km resolution is needed to resolve steep SMB gradients near the GrIS margins, whereas CESM has a nominal resolution of 1° (~100 km). We apply, for the first time, regional grid refinement (55 and 28 km) to the Greenland region using Variable Resolution CESM. We find that although precipitation is greatly improved with enhanced resolution, surface runoff is not. Our third study evaluates the present-day GrIS climate in CESM version 2 (CESM2). We find that CESM2 overestimates the net radiative input at the surface in summer, primarily driven by a low biased albedo, which is compensating for a lack in sensible turbulent heat flux. GrIS ablation zones do not always overlap with that in RACMO2, but the difference in total ablation area is small (-11%). Integrated amounts of SMB components melt, refreezing and runoff are all bracketed by RACMO2 equivalents at the resolutions 11 km (native) and 1 km (statistically down- scaled), indicating a good performance. Our last study explores the future timing of GrIS SMB turning from positive to negative. If such ... |
author2 |
Broeke, M.R. van den Lenaerts, J.T.M. |
format |
Doctoral or Postdoctoral Thesis |
author |
van Kampenhout, Leonardus |
author_facet |
van Kampenhout, Leonardus |
author_sort |
van Kampenhout, Leonardus |
title |
Simulating the Greenland Ice Sheet Surface Mass Balance using an Earth System Model |
title_short |
Simulating the Greenland Ice Sheet Surface Mass Balance using an Earth System Model |
title_full |
Simulating the Greenland Ice Sheet Surface Mass Balance using an Earth System Model |
title_fullStr |
Simulating the Greenland Ice Sheet Surface Mass Balance using an Earth System Model |
title_full_unstemmed |
Simulating the Greenland Ice Sheet Surface Mass Balance using an Earth System Model |
title_sort |
simulating the greenland ice sheet surface mass balance using an earth system model |
publisher |
Utrecht University |
publishDate |
2020 |
url |
https://dspace.library.uu.nl/handle/1874/400695 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Groenland Ice Sheet |
genre_facet |
Greenland Groenland Ice Sheet |
op_relation |
https://dspace.library.uu.nl/handle/1874/400695 |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1772182715484864512 |