Sensitivity of South American tropical climate to Last Glacial Maximum boundary conditions: focus on teleconnections with tropics and extratropics (Invited)
International audience Proxy data over tropical latitudes for the Last Glacial Maximum (LGM) has been interpreted as a southward shift of the Inter Tropical Convergence Zone (ITCZ) and so far linked to a mechanism analogous to the modern day “meridional-mode” in the Atlantic Ocean. Here we have expl...
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HAL CCSD
2009
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Online Access: | https://hal.science/hal-04113538 |
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HAL Sorbonne Université |
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English |
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3337 ATMOSPHERIC PROCESSES / Global climate models 4926 PALEOCEANOGRAPHY / Glacial 4938 PALEOCEANOGRAPHY / Interhemispheric phasing 9360 GEOGRAPHIC LOCATION / South America [SDU]Sciences of the Universe [physics] |
spellingShingle |
3337 ATMOSPHERIC PROCESSES / Global climate models 4926 PALEOCEANOGRAPHY / Glacial 4938 PALEOCEANOGRAPHY / Interhemispheric phasing 9360 GEOGRAPHIC LOCATION / South America [SDU]Sciences of the Universe [physics] Khodri, Myriam Kageyama, Masa Roche, D. M. Sensitivity of South American tropical climate to Last Glacial Maximum boundary conditions: focus on teleconnections with tropics and extratropics (Invited) |
topic_facet |
3337 ATMOSPHERIC PROCESSES / Global climate models 4926 PALEOCEANOGRAPHY / Glacial 4938 PALEOCEANOGRAPHY / Interhemispheric phasing 9360 GEOGRAPHIC LOCATION / South America [SDU]Sciences of the Universe [physics] |
description |
International audience Proxy data over tropical latitudes for the Last Glacial Maximum (LGM) has been interpreted as a southward shift of the Inter Tropical Convergence Zone (ITCZ) and so far linked to a mechanism analogous to the modern day “meridional-mode” in the Atlantic Ocean. Here we have explored alternative mechanisms, related to the direct impact of the LGM global changes in the dry static stability on tropical moist deep convection. We have used a coupled ocean-atmosphere model capable of capturing the thermodynamical structure of the atmosphere and the tropical component of the Hadley and Walker circulations. In each experiment, we have applied either all the LGM forcings, or the individual contributions of greenhouse gases (GHG) concentrations, ice sheet topography and/or albedo to explore the hydrological response over tropical latitudes with a focus on South America. The dominant forcing for the LGM tropical temperature and precipitation changes is found to be due to the reduced GHG, through the direct effect of reduced radiative heating (Clausius-Clapeyron relationship). The LGM GHG is also responsible for increased extra-tropical static stability which strengthens the Hadley Cell. Stronger subsidence over northern tropics then produces an amplification of the northern tropics drying initially due to the direct cooling effect. The land ice sheet is also able to promote the Hadley cell feedback mostly via the topographic effect on the extra-tropical dry static stability and on the position of the subtropical jets. Our results therefore suggest that the communication between the extratropics and the tropics is tighter during LGM and does not necessarily rely on the “meridional-mode” mechanism. The Hadley cell response is constrained by the requirement that diabatic heating in the tropics balances cooling in subtropics. We show that such extratropics-tropics dependence is stronger at the LGM because of the stronger perturbation of northern extra tropical thermal and dynamical equilibrium due to ... |
author2 |
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) Laboratoire des Sciences du Climat et de l'Environnement (LSCE) Commissariat à l'énergie atomique et aux énergies alternatives (CEA) AGU |
format |
Conference Object |
author |
Khodri, Myriam Kageyama, Masa Roche, D. M. |
author_facet |
Khodri, Myriam Kageyama, Masa Roche, D. M. |
author_sort |
Khodri, Myriam |
title |
Sensitivity of South American tropical climate to Last Glacial Maximum boundary conditions: focus on teleconnections with tropics and extratropics (Invited) |
title_short |
Sensitivity of South American tropical climate to Last Glacial Maximum boundary conditions: focus on teleconnections with tropics and extratropics (Invited) |
title_full |
Sensitivity of South American tropical climate to Last Glacial Maximum boundary conditions: focus on teleconnections with tropics and extratropics (Invited) |
title_fullStr |
Sensitivity of South American tropical climate to Last Glacial Maximum boundary conditions: focus on teleconnections with tropics and extratropics (Invited) |
title_full_unstemmed |
Sensitivity of South American tropical climate to Last Glacial Maximum boundary conditions: focus on teleconnections with tropics and extratropics (Invited) |
title_sort |
sensitivity of south american tropical climate to last glacial maximum boundary conditions: focus on teleconnections with tropics and extratropics (invited) |
publisher |
HAL CCSD |
publishDate |
2009 |
url |
https://hal.science/hal-04113538 |
op_coverage |
San Francisco, United States |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
AGU Fall Meeting 2009 https://hal.science/hal-04113538 AGU Fall Meeting 2009, AGU, Dec 2009, San Francisco, United States |
op_relation |
hal-04113538 https://hal.science/hal-04113538 BIBCODE: 2009AGUFM.A11G.01K |
_version_ |
1799481814618734592 |
spelling |
ftsorbonneuniv:oai:HAL:hal-04113538v1 2024-05-19T07:42:10+00:00 Sensitivity of South American tropical climate to Last Glacial Maximum boundary conditions: focus on teleconnections with tropics and extratropics (Invited) Khodri, Myriam Kageyama, Masa Roche, D. M. 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) Laboratoire des Sciences du Climat et de l'Environnement (LSCE) Commissariat à l'énergie atomique et aux énergies alternatives (CEA) AGU San Francisco, United States 2009-12-14 https://hal.science/hal-04113538 en eng HAL CCSD hal-04113538 https://hal.science/hal-04113538 BIBCODE: 2009AGUFM.A11G.01K AGU Fall Meeting 2009 https://hal.science/hal-04113538 AGU Fall Meeting 2009, AGU, Dec 2009, San Francisco, United States 3337 ATMOSPHERIC PROCESSES / Global climate models 4926 PALEOCEANOGRAPHY / Glacial 4938 PALEOCEANOGRAPHY / Interhemispheric phasing 9360 GEOGRAPHIC LOCATION / South America [SDU]Sciences of the Universe [physics] info:eu-repo/semantics/conferenceObject Conference papers 2009 ftsorbonneuniv 2024-04-25T03:46:33Z International audience Proxy data over tropical latitudes for the Last Glacial Maximum (LGM) has been interpreted as a southward shift of the Inter Tropical Convergence Zone (ITCZ) and so far linked to a mechanism analogous to the modern day “meridional-mode” in the Atlantic Ocean. Here we have explored alternative mechanisms, related to the direct impact of the LGM global changes in the dry static stability on tropical moist deep convection. We have used a coupled ocean-atmosphere model capable of capturing the thermodynamical structure of the atmosphere and the tropical component of the Hadley and Walker circulations. In each experiment, we have applied either all the LGM forcings, or the individual contributions of greenhouse gases (GHG) concentrations, ice sheet topography and/or albedo to explore the hydrological response over tropical latitudes with a focus on South America. The dominant forcing for the LGM tropical temperature and precipitation changes is found to be due to the reduced GHG, through the direct effect of reduced radiative heating (Clausius-Clapeyron relationship). The LGM GHG is also responsible for increased extra-tropical static stability which strengthens the Hadley Cell. Stronger subsidence over northern tropics then produces an amplification of the northern tropics drying initially due to the direct cooling effect. The land ice sheet is also able to promote the Hadley cell feedback mostly via the topographic effect on the extra-tropical dry static stability and on the position of the subtropical jets. Our results therefore suggest that the communication between the extratropics and the tropics is tighter during LGM and does not necessarily rely on the “meridional-mode” mechanism. The Hadley cell response is constrained by the requirement that diabatic heating in the tropics balances cooling in subtropics. We show that such extratropics-tropics dependence is stronger at the LGM because of the stronger perturbation of northern extra tropical thermal and dynamical equilibrium due to ... Conference Object Ice Sheet HAL Sorbonne Université |