Estimation of the Antarctic surface mass balance using the regional climate model MAR (1979-2015) and identification of dominant processes
The Antarctic ice sheet mass balance is a major component of the sea level budget and results from the difference of two fluxes of a similar magnitude: ice flow discharging in the ocean and net snow accumulation on the ice sheet surface, i.e. the surface mass balance (SMB). Separately modelling ice...
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ftunivutrecht:oai:dspace.library.uu.nl:1874/378182 2023-11-12T04:05:05+01:00 Estimation of the Antarctic surface mass balance using the regional climate model MAR (1979-2015) and identification of dominant processes Agosta, Cecile Amory, Charles Kittel, Christoph Orsi, Anais Favier, Vincent Gallee, Hubert van den Broeke, Michiel R. Lenaerts, Jan T. M. van Wessem, Jan Melchior van de Berg, Willem Jan Fettweis, Xavier Sub Dynamics Meteorology Marine and Atmospheric Research 2019-01-29 image/pdf https://dspace.library.uu.nl/handle/1874/378182 en eng 1994-0416 https://dspace.library.uu.nl/handle/1874/378182 info:eu-repo/semantics/OpenAccess Article 2019 ftunivutrecht 2023-11-01T23:20:29Z The Antarctic ice sheet mass balance is a major component of the sea level budget and results from the difference of two fluxes of a similar magnitude: ice flow discharging in the ocean and net snow accumulation on the ice sheet surface, i.e. the surface mass balance (SMB). Separately modelling ice dynamics and SMB is the only way to project future trends. In addition, mass balance studies frequently use regional climate models (RCMs) outputs as an alternative to observed fields because SMB observations are particularly scarce on the ice sheet. Here we evaluate new simulations of the polar RCM MAR forced by three reanalyses, ERA-Interim, JRA-55, and MERRA-2, for the period 1979–2015, and we compare MAR results to the last outputs of the RCM RACMO2 forced by ERA-Interim. We show that MAR and RACMO2 perform similarly well in simulating coast-to-plateau SMB gradients, and we find no significant differences in their simulated SMB when integrated over the ice sheet or its major basins. More importantly, we outline and quantify missing or underestimated processes in both RCMs. Along stake transects, we show that both models accumulate too much snow on crests, and not enough snow in valleys, as a result of drifting snow transport fluxes not included in MAR and probably underestimated in RACMO2 by a factor of 3. Our results tend to confirm that drifting snow transport and sublimation fluxes are much larger than previous model-based estimates and need to be better resolved and constrained in climate models. Sublimation of precipitating particles in low-level atmospheric layers is responsible for the significantly lower snowfall rates in MAR than in RACMO2 in katabatic channels at the ice sheet margins. Atmospheric sublimation in MAR represents 363 Gt yr−1 over the grounded ice sheet for the year 2015, which is 16 % of the simulated snowfall loaded at the ground. This estimate is consistent with a recent study based on precipitation radar observations and is more than twice as much as simulated in RACMO2 because of ... Article in Journal/Newspaper Antarc* Antarctic Ice Sheet Utrecht University Repository Antarctic Merra ENVELOPE(12.615,12.615,65.816,65.816) The Antarctic |
institution |
Open Polar |
collection |
Utrecht University Repository |
op_collection_id |
ftunivutrecht |
language |
English |
description |
The Antarctic ice sheet mass balance is a major component of the sea level budget and results from the difference of two fluxes of a similar magnitude: ice flow discharging in the ocean and net snow accumulation on the ice sheet surface, i.e. the surface mass balance (SMB). Separately modelling ice dynamics and SMB is the only way to project future trends. In addition, mass balance studies frequently use regional climate models (RCMs) outputs as an alternative to observed fields because SMB observations are particularly scarce on the ice sheet. Here we evaluate new simulations of the polar RCM MAR forced by three reanalyses, ERA-Interim, JRA-55, and MERRA-2, for the period 1979–2015, and we compare MAR results to the last outputs of the RCM RACMO2 forced by ERA-Interim. We show that MAR and RACMO2 perform similarly well in simulating coast-to-plateau SMB gradients, and we find no significant differences in their simulated SMB when integrated over the ice sheet or its major basins. More importantly, we outline and quantify missing or underestimated processes in both RCMs. Along stake transects, we show that both models accumulate too much snow on crests, and not enough snow in valleys, as a result of drifting snow transport fluxes not included in MAR and probably underestimated in RACMO2 by a factor of 3. Our results tend to confirm that drifting snow transport and sublimation fluxes are much larger than previous model-based estimates and need to be better resolved and constrained in climate models. Sublimation of precipitating particles in low-level atmospheric layers is responsible for the significantly lower snowfall rates in MAR than in RACMO2 in katabatic channels at the ice sheet margins. Atmospheric sublimation in MAR represents 363 Gt yr−1 over the grounded ice sheet for the year 2015, which is 16 % of the simulated snowfall loaded at the ground. This estimate is consistent with a recent study based on precipitation radar observations and is more than twice as much as simulated in RACMO2 because of ... |
author2 |
Sub Dynamics Meteorology Marine and Atmospheric Research |
format |
Article in Journal/Newspaper |
author |
Agosta, Cecile Amory, Charles Kittel, Christoph Orsi, Anais Favier, Vincent Gallee, Hubert van den Broeke, Michiel R. Lenaerts, Jan T. M. van Wessem, Jan Melchior van de Berg, Willem Jan Fettweis, Xavier |
spellingShingle |
Agosta, Cecile Amory, Charles Kittel, Christoph Orsi, Anais Favier, Vincent Gallee, Hubert van den Broeke, Michiel R. Lenaerts, Jan T. M. van Wessem, Jan Melchior van de Berg, Willem Jan Fettweis, Xavier Estimation of the Antarctic surface mass balance using the regional climate model MAR (1979-2015) and identification of dominant processes |
author_facet |
Agosta, Cecile Amory, Charles Kittel, Christoph Orsi, Anais Favier, Vincent Gallee, Hubert van den Broeke, Michiel R. Lenaerts, Jan T. M. van Wessem, Jan Melchior van de Berg, Willem Jan Fettweis, Xavier |
author_sort |
Agosta, Cecile |
title |
Estimation of the Antarctic surface mass balance using the regional climate model MAR (1979-2015) and identification of dominant processes |
title_short |
Estimation of the Antarctic surface mass balance using the regional climate model MAR (1979-2015) and identification of dominant processes |
title_full |
Estimation of the Antarctic surface mass balance using the regional climate model MAR (1979-2015) and identification of dominant processes |
title_fullStr |
Estimation of the Antarctic surface mass balance using the regional climate model MAR (1979-2015) and identification of dominant processes |
title_full_unstemmed |
Estimation of the Antarctic surface mass balance using the regional climate model MAR (1979-2015) and identification of dominant processes |
title_sort |
estimation of the antarctic surface mass balance using the regional climate model mar (1979-2015) and identification of dominant processes |
publishDate |
2019 |
url |
https://dspace.library.uu.nl/handle/1874/378182 |
long_lat |
ENVELOPE(12.615,12.615,65.816,65.816) |
geographic |
Antarctic Merra The Antarctic |
geographic_facet |
Antarctic Merra The Antarctic |
genre |
Antarc* Antarctic Ice Sheet |
genre_facet |
Antarc* Antarctic Ice Sheet |
op_relation |
1994-0416 https://dspace.library.uu.nl/handle/1874/378182 |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1782341880505171968 |