Are 100 ensemble members enough to capture the remote atmospheric response to 12°C arctic sea ice loss?
This study presents results from the Polar Amplification Multimodel Intercomparison Project (PAMIP) single-year time-slice experiments that aim to isolate the atmospheric response to Arctic sea ice loss at global warming levels of 128C. Using two general circulation models (GCMs), the ensemble size...
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eScholarship, University of California
2021
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ftcdlib:oai:escholarship.org/ark:/13030/qt5r49771s 2023-05-15T14:54:48+02:00 Are 100 ensemble members enough to capture the remote atmospheric response to 12°C arctic sea ice loss? Peings, Y Labe, ZM Magnusdottir, G 3751 - 3769 2021-05-15 application/pdf https://escholarship.org/uc/item/5r49771s unknown eScholarship, University of California qt5r49771s https://escholarship.org/uc/item/5r49771s CC-BY CC-BY Journal of Climate, vol 34, iss 10 Arctic Sea ice Atmosphere-ocean interaction Teleconnections Numerical analysis modeling Climate variability Atmospheric Sciences Oceanography Geomatic Engineering Meteorology & Atmospheric Sciences article 2021 ftcdlib 2021-10-11T17:15:26Z This study presents results from the Polar Amplification Multimodel Intercomparison Project (PAMIP) single-year time-slice experiments that aim to isolate the atmospheric response to Arctic sea ice loss at global warming levels of 128C. Using two general circulation models (GCMs), the ensemble size is increased up to 300 ensemble members, beyond the recommended 100 members. After partitioning the response in groups of 100 ensemble members, the reproducibility of the results is evaluated, with a focus on the response of the midlatitude jet streams in the North Atlantic and North Pacific. Both atmosphere-only and coupled ocean–atmosphere PAMIP experiments are analyzed. Substantial differences in the midlatitude response are found among the different experiment subsets, suggesting that 100-member ensembles are still significantly influenced by internal variability, which can mislead conclusions. Despite an overall stronger response, the coupled ocean–atmosphere runs exhibit greater spread due to additional ENSO-related internal variability when the ocean is interactive. The lack of consistency in the response is true for anomalies that are statistically significant according to Student’s t and false discovery rate tests. This is problematic for the multimodel assessment of the response, as some of the spread may be attributed to different model sensitivities whereas it is due to internal variability. We propose a method to overcome this consistency issue that allows for more robust conclusions when only 100 ensemble members are used. Article in Journal/Newspaper Arctic Global warming North Atlantic Sea ice University of California: eScholarship Arctic Pacific |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
unknown |
topic |
Arctic Sea ice Atmosphere-ocean interaction Teleconnections Numerical analysis modeling Climate variability Atmospheric Sciences Oceanography Geomatic Engineering Meteorology & Atmospheric Sciences |
spellingShingle |
Arctic Sea ice Atmosphere-ocean interaction Teleconnections Numerical analysis modeling Climate variability Atmospheric Sciences Oceanography Geomatic Engineering Meteorology & Atmospheric Sciences Peings, Y Labe, ZM Magnusdottir, G Are 100 ensemble members enough to capture the remote atmospheric response to 12°C arctic sea ice loss? |
topic_facet |
Arctic Sea ice Atmosphere-ocean interaction Teleconnections Numerical analysis modeling Climate variability Atmospheric Sciences Oceanography Geomatic Engineering Meteorology & Atmospheric Sciences |
description |
This study presents results from the Polar Amplification Multimodel Intercomparison Project (PAMIP) single-year time-slice experiments that aim to isolate the atmospheric response to Arctic sea ice loss at global warming levels of 128C. Using two general circulation models (GCMs), the ensemble size is increased up to 300 ensemble members, beyond the recommended 100 members. After partitioning the response in groups of 100 ensemble members, the reproducibility of the results is evaluated, with a focus on the response of the midlatitude jet streams in the North Atlantic and North Pacific. Both atmosphere-only and coupled ocean–atmosphere PAMIP experiments are analyzed. Substantial differences in the midlatitude response are found among the different experiment subsets, suggesting that 100-member ensembles are still significantly influenced by internal variability, which can mislead conclusions. Despite an overall stronger response, the coupled ocean–atmosphere runs exhibit greater spread due to additional ENSO-related internal variability when the ocean is interactive. The lack of consistency in the response is true for anomalies that are statistically significant according to Student’s t and false discovery rate tests. This is problematic for the multimodel assessment of the response, as some of the spread may be attributed to different model sensitivities whereas it is due to internal variability. We propose a method to overcome this consistency issue that allows for more robust conclusions when only 100 ensemble members are used. |
format |
Article in Journal/Newspaper |
author |
Peings, Y Labe, ZM Magnusdottir, G |
author_facet |
Peings, Y Labe, ZM Magnusdottir, G |
author_sort |
Peings, Y |
title |
Are 100 ensemble members enough to capture the remote atmospheric response to 12°C arctic sea ice loss? |
title_short |
Are 100 ensemble members enough to capture the remote atmospheric response to 12°C arctic sea ice loss? |
title_full |
Are 100 ensemble members enough to capture the remote atmospheric response to 12°C arctic sea ice loss? |
title_fullStr |
Are 100 ensemble members enough to capture the remote atmospheric response to 12°C arctic sea ice loss? |
title_full_unstemmed |
Are 100 ensemble members enough to capture the remote atmospheric response to 12°C arctic sea ice loss? |
title_sort |
are 100 ensemble members enough to capture the remote atmospheric response to 12°c arctic sea ice loss? |
publisher |
eScholarship, University of California |
publishDate |
2021 |
url |
https://escholarship.org/uc/item/5r49771s |
op_coverage |
3751 - 3769 |
geographic |
Arctic Pacific |
geographic_facet |
Arctic Pacific |
genre |
Arctic Global warming North Atlantic Sea ice |
genre_facet |
Arctic Global warming North Atlantic Sea ice |
op_source |
Journal of Climate, vol 34, iss 10 |
op_relation |
qt5r49771s https://escholarship.org/uc/item/5r49771s |
op_rights |
CC-BY |
op_rightsnorm |
CC-BY |
_version_ |
1766326544028925952 |