Subpolar Southern Ocean response to changes in the surface momentum, heat, and freshwater fluxes under 2xCO2
The Antarctic subpolar Southern Ocean (sSO) has fundamental climate importance. Antarctic Bottom Water (AABW) originates in the sSO and supplies the lower limb of the meridional overturning circulation (MOC), occupying 36% of ocean volume. Climate models struggle to represent continental shelf proce...
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ftunivhelsihelda:oai:helda.helsinki.fi:10138/342582 2024-01-07T09:38:31+01:00 Subpolar Southern Ocean response to changes in the surface momentum, heat, and freshwater fluxes under 2xCO2 Boeira Dias, Fabio Domingues, Catia M. Marsland, Simon J. Rintoul, Stephen R. Uotila, Petteri Fiedler, Russell Mata, Mauricio M. Bindoff, Nathaniel L. Savita, Abhishek Institute for Atmospheric and Earth System Research (INAR) 2022-04-07T22:17:26Z 21 application/pdf http://hdl.handle.net/10138/342582 eng eng American Meteorological Society 10.1175/JCLI-D-21-0161.1 Boeira Dias , F , Domingues , C M , Marsland , S J , Rintoul , S R , Uotila , P , Fiedler , R , Mata , M M , Bindoff , N L & Savita , A 2021 , ' Subpolar Southern Ocean response to changes in the surface momentum, heat, and freshwater fluxes under 2xCO2 ' , Journal of Climate , vol. 34 , no. 21 , pp. 8755–8775 . https://doi.org/10.1175/JCLI-D-21-0161.1 ORCID: /0000-0002-2939-7561/work/102684957 ORCID: /0000-0002-2965-2120/work/102685249 5ffb1a2f-22d9-4038-a483-45a0044e995e http://hdl.handle.net/10138/342582 000752640800018 other openAccess info:eu-repo/semantics/openAccess 114 Physical sciences 1171 Geosciences 1172 Environmental sciences Article publishedVersion 2022 ftunivhelsihelda 2023-12-14T00:07:16Z The Antarctic subpolar Southern Ocean (sSO) has fundamental climate importance. Antarctic Bottom Water (AABW) originates in the sSO and supplies the lower limb of the meridional overturning circulation (MOC), occupying 36% of ocean volume. Climate models struggle to represent continental shelf processes that form AABW. We explore sources of persistent model biases by examining response of the sSO to perturbations in surface forcing in a global ocean–sea ice model (ACCESS-OM2) that forms AABW both on shelf and in open ocean. The sSO response to individual and combined perturbations of surface heat, freshwater, and momentum fluxes follows the WCRP CMIP6 FAFMIP-protocol. Wind perturbation (i.e., a poleward shift and intensification of the westerlies) is dominant, enhancing AABW formation and accelerating the global MOC. This occurs through upwelling of warm waters and inhibition of sea ice growth during winter, which triggers large open water polynya (OWP) events with associated deep convection. These events occur in the Weddell and Ross Seas and their variability is associated with availability of heat at midocean depths. These OWPs cease when the heat reservoir is depleted. Effects of surface warming and freshening only partially compensate changes from increasing winds on ocean stratification and depletion of AABW formation. These results indicate that overly convective models, such ACCESS-OM2, can respond to CO2-perturbed scenarios by forming too much AABW in OWP, which might not hold in models without OWPs. This might contribute to the large intermodel spread thermosteric sea level projections, being relevant to the interpretation of future projections by current climate models. Peer reviewed Article in Journal/Newspaper Antarc* Antarctic Sea ice Southern Ocean HELDA – University of Helsinki Open Repository Antarctic Southern Ocean The Antarctic Weddell Journal of Climate 34 21 8755 8775 |
institution |
Open Polar |
collection |
HELDA – University of Helsinki Open Repository |
op_collection_id |
ftunivhelsihelda |
language |
English |
topic |
114 Physical sciences 1171 Geosciences 1172 Environmental sciences |
spellingShingle |
114 Physical sciences 1171 Geosciences 1172 Environmental sciences Boeira Dias, Fabio Domingues, Catia M. Marsland, Simon J. Rintoul, Stephen R. Uotila, Petteri Fiedler, Russell Mata, Mauricio M. Bindoff, Nathaniel L. Savita, Abhishek Subpolar Southern Ocean response to changes in the surface momentum, heat, and freshwater fluxes under 2xCO2 |
topic_facet |
114 Physical sciences 1171 Geosciences 1172 Environmental sciences |
description |
The Antarctic subpolar Southern Ocean (sSO) has fundamental climate importance. Antarctic Bottom Water (AABW) originates in the sSO and supplies the lower limb of the meridional overturning circulation (MOC), occupying 36% of ocean volume. Climate models struggle to represent continental shelf processes that form AABW. We explore sources of persistent model biases by examining response of the sSO to perturbations in surface forcing in a global ocean–sea ice model (ACCESS-OM2) that forms AABW both on shelf and in open ocean. The sSO response to individual and combined perturbations of surface heat, freshwater, and momentum fluxes follows the WCRP CMIP6 FAFMIP-protocol. Wind perturbation (i.e., a poleward shift and intensification of the westerlies) is dominant, enhancing AABW formation and accelerating the global MOC. This occurs through upwelling of warm waters and inhibition of sea ice growth during winter, which triggers large open water polynya (OWP) events with associated deep convection. These events occur in the Weddell and Ross Seas and their variability is associated with availability of heat at midocean depths. These OWPs cease when the heat reservoir is depleted. Effects of surface warming and freshening only partially compensate changes from increasing winds on ocean stratification and depletion of AABW formation. These results indicate that overly convective models, such ACCESS-OM2, can respond to CO2-perturbed scenarios by forming too much AABW in OWP, which might not hold in models without OWPs. This might contribute to the large intermodel spread thermosteric sea level projections, being relevant to the interpretation of future projections by current climate models. Peer reviewed |
author2 |
Institute for Atmospheric and Earth System Research (INAR) |
format |
Article in Journal/Newspaper |
author |
Boeira Dias, Fabio Domingues, Catia M. Marsland, Simon J. Rintoul, Stephen R. Uotila, Petteri Fiedler, Russell Mata, Mauricio M. Bindoff, Nathaniel L. Savita, Abhishek |
author_facet |
Boeira Dias, Fabio Domingues, Catia M. Marsland, Simon J. Rintoul, Stephen R. Uotila, Petteri Fiedler, Russell Mata, Mauricio M. Bindoff, Nathaniel L. Savita, Abhishek |
author_sort |
Boeira Dias, Fabio |
title |
Subpolar Southern Ocean response to changes in the surface momentum, heat, and freshwater fluxes under 2xCO2 |
title_short |
Subpolar Southern Ocean response to changes in the surface momentum, heat, and freshwater fluxes under 2xCO2 |
title_full |
Subpolar Southern Ocean response to changes in the surface momentum, heat, and freshwater fluxes under 2xCO2 |
title_fullStr |
Subpolar Southern Ocean response to changes in the surface momentum, heat, and freshwater fluxes under 2xCO2 |
title_full_unstemmed |
Subpolar Southern Ocean response to changes in the surface momentum, heat, and freshwater fluxes under 2xCO2 |
title_sort |
subpolar southern ocean response to changes in the surface momentum, heat, and freshwater fluxes under 2xco2 |
publisher |
American Meteorological Society |
publishDate |
2022 |
url |
http://hdl.handle.net/10138/342582 |
geographic |
Antarctic Southern Ocean The Antarctic Weddell |
geographic_facet |
Antarctic Southern Ocean The Antarctic Weddell |
genre |
Antarc* Antarctic Sea ice Southern Ocean |
genre_facet |
Antarc* Antarctic Sea ice Southern Ocean |
op_relation |
10.1175/JCLI-D-21-0161.1 Boeira Dias , F , Domingues , C M , Marsland , S J , Rintoul , S R , Uotila , P , Fiedler , R , Mata , M M , Bindoff , N L & Savita , A 2021 , ' Subpolar Southern Ocean response to changes in the surface momentum, heat, and freshwater fluxes under 2xCO2 ' , Journal of Climate , vol. 34 , no. 21 , pp. 8755–8775 . https://doi.org/10.1175/JCLI-D-21-0161.1 ORCID: /0000-0002-2939-7561/work/102684957 ORCID: /0000-0002-2965-2120/work/102685249 5ffb1a2f-22d9-4038-a483-45a0044e995e http://hdl.handle.net/10138/342582 000752640800018 |
op_rights |
other openAccess info:eu-repo/semantics/openAccess |
container_title |
Journal of Climate |
container_volume |
34 |
container_issue |
21 |
container_start_page |
8755 |
op_container_end_page |
8775 |
_version_ |
1787423600739876864 |