Alleviation of an Arctic Sea Ice Bias in a Coupled Model Through Modifications in the Subgrid‐Scale Orographic Parameterization
Abstract In climate models, the subgrid‐scale orography (SSO) parameterization imposes a blocked flow drag at low levels that is opposed to the local flow. In IPSL‐CM6A‐LR, an SSO lift force is also applied perpendicular to the local flow to account for the effect of locally blocked air in narrow va...
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ftdoajarticles:oai:doaj.org/article:fbc1c51273cb41a7b06ade0e764787ca 2023-05-15T13:11:17+02:00 Alleviation of an Arctic Sea Ice Bias in a Coupled Model Through Modifications in the Subgrid‐Scale Orographic Parameterization Guillaume Gastineau François Lott Juliette Mignot Frederic Hourdin 2020-09-01T00:00:00Z https://doi.org/10.1029/2020MS002111 https://doaj.org/article/fbc1c51273cb41a7b06ade0e764787ca EN eng American Geophysical Union (AGU) https://doi.org/10.1029/2020MS002111 https://doaj.org/toc/1942-2466 1942-2466 doi:10.1029/2020MS002111 https://doaj.org/article/fbc1c51273cb41a7b06ade0e764787ca Journal of Advances in Modeling Earth Systems, Vol 12, Iss 9, Pp n/a-n/a (2020) climate models orography atmospheric dynamics air‐sea interaction Arctic Ocean Physical geography GB3-5030 Oceanography GC1-1581 article 2020 ftdoajarticles https://doi.org/10.1029/2020MS002111 2022-12-31T11:40:43Z Abstract In climate models, the subgrid‐scale orography (SSO) parameterization imposes a blocked flow drag at low levels that is opposed to the local flow. In IPSL‐CM6A‐LR, an SSO lift force is also applied perpendicular to the local flow to account for the effect of locally blocked air in narrow valleys. Using IPSL‐CM6A‐LR sensitivity experiments, it is found that the tuning of both effects strongly impacts the atmospheric circulation. Increasing the blocking and reducing the lift lead to an equatorward shift of the Northern Hemisphere subtropical jet and a reduction of the midlatitude eddy‐driven jet speed. It also improves the simulated synoptic variability, with a reduced storm‐track intensity and increased blocking frequency over Greenland and Scandinavia. Additionally, it cools the polar lower troposphere in boreal winter. Transformed Eulerian Mean diagnostics also show that the low‐level eddy‐driven subsidence over the polar region is reduced consistent with the simulated cooling. The changes are amplified in coupled experiments when compared to atmosphere‐only experiments, as the low‐troposphere polar cooling is further amplified by the temperature and albedo feedbacks resulting from the Arctic sea ice growth. In IPSL‐CM6A‐LR, this corrects the warm winter bias and the lack of sea ice that were present over the Arctic before adjusting the SSO parameters. Our results, therefore, suggest that the adjustment of SSO parameterization alleviates the Arctic sea ice bias in this case. However, the atmospheric changes induced by the parametrized SSO also impact the ocean, with an equatorward shift of the Northern Hemisphere oceanic gyres and a weaker Atlantic meridional overturning circulation. Article in Journal/Newspaper albedo Arctic Arctic Ocean Greenland Sea ice Directory of Open Access Journals: DOAJ Articles Arctic Arctic Ocean Greenland Journal of Advances in Modeling Earth Systems 12 9 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
climate models orography atmospheric dynamics air‐sea interaction Arctic Ocean Physical geography GB3-5030 Oceanography GC1-1581 |
spellingShingle |
climate models orography atmospheric dynamics air‐sea interaction Arctic Ocean Physical geography GB3-5030 Oceanography GC1-1581 Guillaume Gastineau François Lott Juliette Mignot Frederic Hourdin Alleviation of an Arctic Sea Ice Bias in a Coupled Model Through Modifications in the Subgrid‐Scale Orographic Parameterization |
topic_facet |
climate models orography atmospheric dynamics air‐sea interaction Arctic Ocean Physical geography GB3-5030 Oceanography GC1-1581 |
description |
Abstract In climate models, the subgrid‐scale orography (SSO) parameterization imposes a blocked flow drag at low levels that is opposed to the local flow. In IPSL‐CM6A‐LR, an SSO lift force is also applied perpendicular to the local flow to account for the effect of locally blocked air in narrow valleys. Using IPSL‐CM6A‐LR sensitivity experiments, it is found that the tuning of both effects strongly impacts the atmospheric circulation. Increasing the blocking and reducing the lift lead to an equatorward shift of the Northern Hemisphere subtropical jet and a reduction of the midlatitude eddy‐driven jet speed. It also improves the simulated synoptic variability, with a reduced storm‐track intensity and increased blocking frequency over Greenland and Scandinavia. Additionally, it cools the polar lower troposphere in boreal winter. Transformed Eulerian Mean diagnostics also show that the low‐level eddy‐driven subsidence over the polar region is reduced consistent with the simulated cooling. The changes are amplified in coupled experiments when compared to atmosphere‐only experiments, as the low‐troposphere polar cooling is further amplified by the temperature and albedo feedbacks resulting from the Arctic sea ice growth. In IPSL‐CM6A‐LR, this corrects the warm winter bias and the lack of sea ice that were present over the Arctic before adjusting the SSO parameters. Our results, therefore, suggest that the adjustment of SSO parameterization alleviates the Arctic sea ice bias in this case. However, the atmospheric changes induced by the parametrized SSO also impact the ocean, with an equatorward shift of the Northern Hemisphere oceanic gyres and a weaker Atlantic meridional overturning circulation. |
format |
Article in Journal/Newspaper |
author |
Guillaume Gastineau François Lott Juliette Mignot Frederic Hourdin |
author_facet |
Guillaume Gastineau François Lott Juliette Mignot Frederic Hourdin |
author_sort |
Guillaume Gastineau |
title |
Alleviation of an Arctic Sea Ice Bias in a Coupled Model Through Modifications in the Subgrid‐Scale Orographic Parameterization |
title_short |
Alleviation of an Arctic Sea Ice Bias in a Coupled Model Through Modifications in the Subgrid‐Scale Orographic Parameterization |
title_full |
Alleviation of an Arctic Sea Ice Bias in a Coupled Model Through Modifications in the Subgrid‐Scale Orographic Parameterization |
title_fullStr |
Alleviation of an Arctic Sea Ice Bias in a Coupled Model Through Modifications in the Subgrid‐Scale Orographic Parameterization |
title_full_unstemmed |
Alleviation of an Arctic Sea Ice Bias in a Coupled Model Through Modifications in the Subgrid‐Scale Orographic Parameterization |
title_sort |
alleviation of an arctic sea ice bias in a coupled model through modifications in the subgrid‐scale orographic parameterization |
publisher |
American Geophysical Union (AGU) |
publishDate |
2020 |
url |
https://doi.org/10.1029/2020MS002111 https://doaj.org/article/fbc1c51273cb41a7b06ade0e764787ca |
geographic |
Arctic Arctic Ocean Greenland |
geographic_facet |
Arctic Arctic Ocean Greenland |
genre |
albedo Arctic Arctic Ocean Greenland Sea ice |
genre_facet |
albedo Arctic Arctic Ocean Greenland Sea ice |
op_source |
Journal of Advances in Modeling Earth Systems, Vol 12, Iss 9, Pp n/a-n/a (2020) |
op_relation |
https://doi.org/10.1029/2020MS002111 https://doaj.org/toc/1942-2466 1942-2466 doi:10.1029/2020MS002111 https://doaj.org/article/fbc1c51273cb41a7b06ade0e764787ca |
op_doi |
https://doi.org/10.1029/2020MS002111 |
container_title |
Journal of Advances in Modeling Earth Systems |
container_volume |
12 |
container_issue |
9 |
_version_ |
1766246712877252608 |