Understanding model spread in sea ice volume by attribution of model differences in seasonal ice growth and melt
Arctic sea ice is declining rapidly, but predictions of its future loss are made difficult by the large spread both in present-day and in future sea ice area and volume; hence, there is a need to better understand the drivers of model spread in sea ice state. Here we present a framework for understa...
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ftcopernicus:oai:publications.copernicus.org:tcd99065 2023-05-15T13:11:40+02:00 Understanding model spread in sea ice volume by attribution of model differences in seasonal ice growth and melt West, Alex Blockley, Ed Collins, Mat 2021-11-22 application/pdf https://doi.org/10.5194/tc-2021-351 https://tc.copernicus.org/preprints/tc-2021-351/ eng eng doi:10.5194/tc-2021-351 https://tc.copernicus.org/preprints/tc-2021-351/ eISSN: 1994-0424 Text 2021 ftcopernicus https://doi.org/10.5194/tc-2021-351 2021-11-29T17:22:30Z Arctic sea ice is declining rapidly, but predictions of its future loss are made difficult by the large spread both in present-day and in future sea ice area and volume; hence, there is a need to better understand the drivers of model spread in sea ice state. Here we present a framework for understanding differences between modelled sea ice simulations based on attributing seasonal ice growth and melt differences. In the method presented, the net downward surface flux is treated as the principal driver of seasonal sea ice growth and melt. A system of simple models is used to estimate the pointwise effect of model differences in key Arctic climate variables on this surface flux, and hence on seasonal sea ice growth and melt. We compare three models with very different historical sea ice simulations: HadGEM2-ES, HadGEM3-GC3.1 and UKESM1.0. The largest driver of differences in ice growth / melt between these models is shown to be the ice area in summer (representing the surface albedo feedback) and the ice thickness distribution in winter (the thickness-growth feedback). Differences in snow and melt-pond cover during the early summer exert a smaller effect on the seasonal growth and melt, hence representing the drivers of model differences in both this and in the sea ice volume. In particular, the direct impacts on sea ice growth / melt of differing model parameterisations of snow area and of melt-ponds are shown to be small but non-negligible. Text albedo Arctic Sea ice Copernicus Publications: E-Journals Arctic |
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Copernicus Publications: E-Journals |
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ftcopernicus |
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English |
description |
Arctic sea ice is declining rapidly, but predictions of its future loss are made difficult by the large spread both in present-day and in future sea ice area and volume; hence, there is a need to better understand the drivers of model spread in sea ice state. Here we present a framework for understanding differences between modelled sea ice simulations based on attributing seasonal ice growth and melt differences. In the method presented, the net downward surface flux is treated as the principal driver of seasonal sea ice growth and melt. A system of simple models is used to estimate the pointwise effect of model differences in key Arctic climate variables on this surface flux, and hence on seasonal sea ice growth and melt. We compare three models with very different historical sea ice simulations: HadGEM2-ES, HadGEM3-GC3.1 and UKESM1.0. The largest driver of differences in ice growth / melt between these models is shown to be the ice area in summer (representing the surface albedo feedback) and the ice thickness distribution in winter (the thickness-growth feedback). Differences in snow and melt-pond cover during the early summer exert a smaller effect on the seasonal growth and melt, hence representing the drivers of model differences in both this and in the sea ice volume. In particular, the direct impacts on sea ice growth / melt of differing model parameterisations of snow area and of melt-ponds are shown to be small but non-negligible. |
format |
Text |
author |
West, Alex Blockley, Ed Collins, Mat |
spellingShingle |
West, Alex Blockley, Ed Collins, Mat Understanding model spread in sea ice volume by attribution of model differences in seasonal ice growth and melt |
author_facet |
West, Alex Blockley, Ed Collins, Mat |
author_sort |
West, Alex |
title |
Understanding model spread in sea ice volume by attribution of model differences in seasonal ice growth and melt |
title_short |
Understanding model spread in sea ice volume by attribution of model differences in seasonal ice growth and melt |
title_full |
Understanding model spread in sea ice volume by attribution of model differences in seasonal ice growth and melt |
title_fullStr |
Understanding model spread in sea ice volume by attribution of model differences in seasonal ice growth and melt |
title_full_unstemmed |
Understanding model spread in sea ice volume by attribution of model differences in seasonal ice growth and melt |
title_sort |
understanding model spread in sea ice volume by attribution of model differences in seasonal ice growth and melt |
publishDate |
2021 |
url |
https://doi.org/10.5194/tc-2021-351 https://tc.copernicus.org/preprints/tc-2021-351/ |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
albedo Arctic Sea ice |
genre_facet |
albedo Arctic Sea ice |
op_source |
eISSN: 1994-0424 |
op_relation |
doi:10.5194/tc-2021-351 https://tc.copernicus.org/preprints/tc-2021-351/ |
op_doi |
https://doi.org/10.5194/tc-2021-351 |
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1766248407300571136 |