Impact of the oceanic geothermal heat flux on a glacial ocean state
International audience The oceanic geothermal heating (OGH) has a significant impact on the present-day ocean state, but its role during glacial periods, when the ocean circulation and stratification were different from those of today, remains poorly known. In the present study, we analyzed the resp...
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2015
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Online Access: | https://hal.science/hal-04115512 https://hal.science/hal-04115512/document https://hal.science/hal-04115512/file/cpd-11-3597-2015.pdf https://doi.org/10.5194/cpd-11-3597-2015 |
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HAL-CEA (Commissariat à l'énergie atomique et aux énergies alternatives) |
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English |
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[SDU]Sciences of the Universe [physics] |
spellingShingle |
[SDU]Sciences of the Universe [physics] Ballarotta, M. Roquet, Fabien Falahat, S. Zhang, Q. Madec, Gurvan Impact of the oceanic geothermal heat flux on a glacial ocean state |
topic_facet |
[SDU]Sciences of the Universe [physics] |
description |
International audience The oceanic geothermal heating (OGH) has a significant impact on the present-day ocean state, but its role during glacial periods, when the ocean circulation and stratification were different from those of today, remains poorly known. In the present study, we analyzed the response of the glacial ocean to OGH, by comparing ocean simulations of the Last Glacial Maximum (LGM, ∼ 21 ka ago) including or not geothermal heating. We found that applying the OGH warmed the Antarctic Bottom Waters (AABW) by ∼ 0.4 °C and increased the abyssal circulation by 15 to 30 % north of 30° S in the deep Pacific and Atlantic basins. The geothermally heated deep waters were then advected toward the Southern Ocean where they upwelled to the surface due to the Ekman transport. The extra heat transport towards Antarctica acted to reduce the amount of sea ice contributing to the freshening of the whole AABW overturning cell. The global amount of salt being conserved, this bottom freshening induced a salinification of the North Atlantic and North Pacific surface and intermediate waters, contributing to the deepening of the North Atlantic Deep Water. This indirect mechanism is responsible for the largest observed warming, found in the North Atlantic deep western boundary current between 2000 and 3000 m (up to 2 °C). The characteristic time scale of the ocean response to the OGH corresponds to an advective time scale (associated with the overturning of the AABW cell) rather than a diffusive time scale. The OGH might facilitate the transition from a glacial to an inter-glacial state but its effect on the deep stratification seems insufficient to drive alone an abrupt climate change. |
author2 |
Bolin Centre for Climate Research Stockholm University Department of Physical Geography Stockholm Department of Meteorology Stockholm (MISU) Department of Environmental Science and Analytical Chemistry Stockholm (ACES) Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN) Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)) École normale supérieure - Paris (ENS-PSL) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Ballarotta, M. Roquet, Fabien Falahat, S. Zhang, Q. Madec, Gurvan |
author_facet |
Ballarotta, M. Roquet, Fabien Falahat, S. Zhang, Q. Madec, Gurvan |
author_sort |
Ballarotta, M. |
title |
Impact of the oceanic geothermal heat flux on a glacial ocean state |
title_short |
Impact of the oceanic geothermal heat flux on a glacial ocean state |
title_full |
Impact of the oceanic geothermal heat flux on a glacial ocean state |
title_fullStr |
Impact of the oceanic geothermal heat flux on a glacial ocean state |
title_full_unstemmed |
Impact of the oceanic geothermal heat flux on a glacial ocean state |
title_sort |
impact of the oceanic geothermal heat flux on a glacial ocean state |
publisher |
HAL CCSD |
publishDate |
2015 |
url |
https://hal.science/hal-04115512 https://hal.science/hal-04115512/document https://hal.science/hal-04115512/file/cpd-11-3597-2015.pdf https://doi.org/10.5194/cpd-11-3597-2015 |
genre |
Antarc* Antarctic Antarctica North Atlantic Deep Water North Atlantic Sea ice Southern Ocean |
genre_facet |
Antarc* Antarctic Antarctica North Atlantic Deep Water North Atlantic Sea ice Southern Ocean |
op_source |
ISSN: 1814-9340 EISSN: 1814-9359 Climate of the Past Discussions https://hal.science/hal-04115512 Climate of the Past Discussions, 2015, 11, pp.3597-3624. ⟨10.5194/cpd-11-3597-2015⟩ |
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info:eu-repo/semantics/altIdentifier/doi/10.5194/cpd-11-3597-2015 hal-04115512 https://hal.science/hal-04115512 https://hal.science/hal-04115512/document https://hal.science/hal-04115512/file/cpd-11-3597-2015.pdf BIBCODE: 2015CliPD.11.3597B doi:10.5194/cpd-11-3597-2015 |
op_rights |
http://creativecommons.org/licenses/by/ info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.5194/cpd-11-3597-2015 |
_version_ |
1810494925702168576 |
spelling |
ftceafr:oai:HAL:hal-04115512v1 2024-09-15T17:46:37+00:00 Impact of the oceanic geothermal heat flux on a glacial ocean state Ballarotta, M. Roquet, Fabien Falahat, S. Zhang, Q. Madec, Gurvan Bolin Centre for Climate Research Stockholm University Department of Physical Geography Stockholm Department of Meteorology Stockholm (MISU) Department of Environmental Science and Analytical Chemistry Stockholm (ACES) Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN) Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)) École normale supérieure - Paris (ENS-PSL) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS) 2015 https://hal.science/hal-04115512 https://hal.science/hal-04115512/document https://hal.science/hal-04115512/file/cpd-11-3597-2015.pdf https://doi.org/10.5194/cpd-11-3597-2015 en eng HAL CCSD European Geosciences Union (EGU) info:eu-repo/semantics/altIdentifier/doi/10.5194/cpd-11-3597-2015 hal-04115512 https://hal.science/hal-04115512 https://hal.science/hal-04115512/document https://hal.science/hal-04115512/file/cpd-11-3597-2015.pdf BIBCODE: 2015CliPD.11.3597B doi:10.5194/cpd-11-3597-2015 http://creativecommons.org/licenses/by/ info:eu-repo/semantics/OpenAccess ISSN: 1814-9340 EISSN: 1814-9359 Climate of the Past Discussions https://hal.science/hal-04115512 Climate of the Past Discussions, 2015, 11, pp.3597-3624. ⟨10.5194/cpd-11-3597-2015⟩ [SDU]Sciences of the Universe [physics] info:eu-repo/semantics/article Journal articles 2015 ftceafr https://doi.org/10.5194/cpd-11-3597-2015 2024-07-22T13:06:09Z International audience The oceanic geothermal heating (OGH) has a significant impact on the present-day ocean state, but its role during glacial periods, when the ocean circulation and stratification were different from those of today, remains poorly known. In the present study, we analyzed the response of the glacial ocean to OGH, by comparing ocean simulations of the Last Glacial Maximum (LGM, ∼ 21 ka ago) including or not geothermal heating. We found that applying the OGH warmed the Antarctic Bottom Waters (AABW) by ∼ 0.4 °C and increased the abyssal circulation by 15 to 30 % north of 30° S in the deep Pacific and Atlantic basins. The geothermally heated deep waters were then advected toward the Southern Ocean where they upwelled to the surface due to the Ekman transport. The extra heat transport towards Antarctica acted to reduce the amount of sea ice contributing to the freshening of the whole AABW overturning cell. The global amount of salt being conserved, this bottom freshening induced a salinification of the North Atlantic and North Pacific surface and intermediate waters, contributing to the deepening of the North Atlantic Deep Water. This indirect mechanism is responsible for the largest observed warming, found in the North Atlantic deep western boundary current between 2000 and 3000 m (up to 2 °C). The characteristic time scale of the ocean response to the OGH corresponds to an advective time scale (associated with the overturning of the AABW cell) rather than a diffusive time scale. The OGH might facilitate the transition from a glacial to an inter-glacial state but its effect on the deep stratification seems insufficient to drive alone an abrupt climate change. Article in Journal/Newspaper Antarc* Antarctic Antarctica North Atlantic Deep Water North Atlantic Sea ice Southern Ocean HAL-CEA (Commissariat à l'énergie atomique et aux énergies alternatives) |