Sea-ice extent and its trend provide limited metrics of model performance
We examine how the evaluation of modelled sea-ice coverage against reality is affected by uncertainties in the retrieval of sea-ice coverage from satellite, by the usage of sea-ice extent to overcome these uncertainties, and by internal variability. We find that for Arctic summer sea ice, model bias...
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ftdoajarticles:oai:doaj.org/article:f4fb22435129435dbd115a8fc2ece64e 2023-05-15T15:00:01+02:00 Sea-ice extent and its trend provide limited metrics of model performance D. Notz 2014-02-01T00:00:00Z https://doi.org/10.5194/tc-8-229-2014 https://doaj.org/article/f4fb22435129435dbd115a8fc2ece64e EN eng Copernicus Publications http://www.the-cryosphere.net/8/229/2014/tc-8-229-2014.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 1994-0416 1994-0424 doi:10.5194/tc-8-229-2014 https://doaj.org/article/f4fb22435129435dbd115a8fc2ece64e The Cryosphere, Vol 8, Iss 1, Pp 229-243 (2014) Environmental sciences GE1-350 Geology QE1-996.5 article 2014 ftdoajarticles https://doi.org/10.5194/tc-8-229-2014 2022-12-30T22:58:37Z We examine how the evaluation of modelled sea-ice coverage against reality is affected by uncertainties in the retrieval of sea-ice coverage from satellite, by the usage of sea-ice extent to overcome these uncertainties, and by internal variability. We find that for Arctic summer sea ice, model biases in sea-ice extent can be qualitatively different from biases in sea-ice area. This is because about half of the CMIP5 models and satellite retrievals based on the Bootstrap and the ASI algorithm show a compact ice cover in summer with large areas of high-concentration sea ice, while the other half of the CMIP5 models and satellite retrievals based on the NASA Team algorithm show a loose ice cover. For the Arctic winter sea-ice cover, differences in grid geometry can cause synthetic biases in sea-ice extent that are larger than the observational uncertainty. Comparing the uncertainty arising directly from the satellite retrievals with those that arise from internal variability, we find that the latter by far dominates the uncertainty estimate for trends in sea-ice extent and area: most of the differences between modelled and observed trends can simply be explained by internal variability. For absolute sea-ice area and sea-ice extent, however, internal variability cannot explain the difference between model and observations for about half the CMIP5 models that we analyse here. All models that we examined have regional biases, as expressed by the root-mean-square error in concentration, that are larger than the differences between individual satellite algorithms. Article in Journal/Newspaper Arctic Sea ice The Cryosphere Directory of Open Access Journals: DOAJ Articles Arctic The Cryosphere 8 1 229 243 |
institution |
Open Polar |
collection |
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 D. Notz Sea-ice extent and its trend provide limited metrics of model performance |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
We examine how the evaluation of modelled sea-ice coverage against reality is affected by uncertainties in the retrieval of sea-ice coverage from satellite, by the usage of sea-ice extent to overcome these uncertainties, and by internal variability. We find that for Arctic summer sea ice, model biases in sea-ice extent can be qualitatively different from biases in sea-ice area. This is because about half of the CMIP5 models and satellite retrievals based on the Bootstrap and the ASI algorithm show a compact ice cover in summer with large areas of high-concentration sea ice, while the other half of the CMIP5 models and satellite retrievals based on the NASA Team algorithm show a loose ice cover. For the Arctic winter sea-ice cover, differences in grid geometry can cause synthetic biases in sea-ice extent that are larger than the observational uncertainty. Comparing the uncertainty arising directly from the satellite retrievals with those that arise from internal variability, we find that the latter by far dominates the uncertainty estimate for trends in sea-ice extent and area: most of the differences between modelled and observed trends can simply be explained by internal variability. For absolute sea-ice area and sea-ice extent, however, internal variability cannot explain the difference between model and observations for about half the CMIP5 models that we analyse here. All models that we examined have regional biases, as expressed by the root-mean-square error in concentration, that are larger than the differences between individual satellite algorithms. |
format |
Article in Journal/Newspaper |
author |
D. Notz |
author_facet |
D. Notz |
author_sort |
D. Notz |
title |
Sea-ice extent and its trend provide limited metrics of model performance |
title_short |
Sea-ice extent and its trend provide limited metrics of model performance |
title_full |
Sea-ice extent and its trend provide limited metrics of model performance |
title_fullStr |
Sea-ice extent and its trend provide limited metrics of model performance |
title_full_unstemmed |
Sea-ice extent and its trend provide limited metrics of model performance |
title_sort |
sea-ice extent and its trend provide limited metrics of model performance |
publisher |
Copernicus Publications |
publishDate |
2014 |
url |
https://doi.org/10.5194/tc-8-229-2014 https://doaj.org/article/f4fb22435129435dbd115a8fc2ece64e |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Sea ice The Cryosphere |
genre_facet |
Arctic Sea ice The Cryosphere |
op_source |
The Cryosphere, Vol 8, Iss 1, Pp 229-243 (2014) |
op_relation |
http://www.the-cryosphere.net/8/229/2014/tc-8-229-2014.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 1994-0416 1994-0424 doi:10.5194/tc-8-229-2014 https://doaj.org/article/f4fb22435129435dbd115a8fc2ece64e |
op_doi |
https://doi.org/10.5194/tc-8-229-2014 |
container_title |
The Cryosphere |
container_volume |
8 |
container_issue |
1 |
container_start_page |
229 |
op_container_end_page |
243 |
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1766332128430129152 |