Relations entre surface océanique et composition isotopique des précipitations antarctiques : simulation pour différents climats
Dr Gavin SCHMIDT Pr Laurent LABEYRIE Dr Laurence VIDAL Dr Christophe GENTHON Dr Jean JOUZEL Pr Edouard BARD Interactions between ocean temperature and isotopic content of Antarctic precipitation are studied with the help of a General Circulation Model (GCM), by distinguishing different geographic so...
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2000
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Online Access: | https://theses.hal.science/tel-00002821 https://theses.hal.science/tel-00002821/document https://theses.hal.science/tel-00002821/file/tel-00002821.pdf |
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ftinsu:oai:HAL:tel-00002821v1 2023-12-17T10:21:35+01:00 Relations entre surface océanique et composition isotopique des précipitations antarctiques : simulation pour différents climats Delaygue, Gilles Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE) Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) Université de droit, d'économie et des sciences - Aix-Marseille III Bard Edouard 2000-02-25 https://theses.hal.science/tel-00002821 https://theses.hal.science/tel-00002821/document https://theses.hal.science/tel-00002821/file/tel-00002821.pdf fr fre HAL CCSD tel-00002821 https://theses.hal.science/tel-00002821 https://theses.hal.science/tel-00002821/document https://theses.hal.science/tel-00002821/file/tel-00002821.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-00002821 Autre. Université de droit, d'économie et des sciences - Aix-Marseille III, 2000. Français. ⟨NNT : ⟩ modélisation géochimie isotopique relation isotope-salinité thermomètre isotopique Antarctique paléoclimat [SDU.OTHER]Sciences of the Universe [physics]/Other info:eu-repo/semantics/doctoralThesis Theses 2000 ftinsu 2023-11-22T17:25:21Z Dr Gavin SCHMIDT Pr Laurent LABEYRIE Dr Laurence VIDAL Dr Christophe GENTHON Dr Jean JOUZEL Pr Edouard BARD Interactions between ocean temperature and isotopic content of Antarctic precipitation are studied with the help of a General Circulation Model (GCM), by distinguishing different geographic sources for the precipitation. The contribution of these sources is estimated for modern as well as glacial (21,000 years ago) climatic conditions. Climatic variations arose from the ocean cooling and the intensification of the meridional gradient of temperature. We have tried different reconstructions of tropical ocean temperatures, which are not well constrained for glacial time, and the source contributions are found quite sensitive to this parameter. For the high latitudes, the isotopic content of precipitation, originating from different sources, are related to the source temperature and its distance to the precipitation site. Contrary to the idea developped by Boyle (1997), a global cooling is not susceptible to bias the classical interpretation of isotopes as paleothermometer, because this cooling is compensated for, in our simulations, by a stronger contribution from the warmer sources. The oceanic field of oxygen-18 is simulated with an ocean GCM, by prescribing at the surface isotopic fluxes derived from the atmospheric GCM. The same fluxes are used to simulate a 'passive' salinity field, consistent with the oxygen-18. The observed features of both fields, as well as their relationships, are well simulated. This modelling allows us to study the sensitivity of their relationships to the surface fluxes, esp. to the continental runoff. The importance of horizontal mixing is estimated by comparing the GCM fields with a box model of the ocean. We also estimate the sensitivity of the deuterium-excess in the Antarctic precipitation to the oceanic temperature, humidity, and isotopic content. L'interaction entre la température des océans et la teneur isotopique des précipitations antarctiques est étudiée à l'aide ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Antarctique* Institut national des sciences de l'Univers: HAL-INSU Antarctic The Antarctic Vidal ENVELOPE(-62.450,-62.450,-64.867,-64.867) |
institution |
Open Polar |
collection |
Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
ftinsu |
language |
French |
topic |
modélisation géochimie isotopique relation isotope-salinité thermomètre isotopique Antarctique paléoclimat [SDU.OTHER]Sciences of the Universe [physics]/Other |
spellingShingle |
modélisation géochimie isotopique relation isotope-salinité thermomètre isotopique Antarctique paléoclimat [SDU.OTHER]Sciences of the Universe [physics]/Other Delaygue, Gilles Relations entre surface océanique et composition isotopique des précipitations antarctiques : simulation pour différents climats |
topic_facet |
modélisation géochimie isotopique relation isotope-salinité thermomètre isotopique Antarctique paléoclimat [SDU.OTHER]Sciences of the Universe [physics]/Other |
description |
Dr Gavin SCHMIDT Pr Laurent LABEYRIE Dr Laurence VIDAL Dr Christophe GENTHON Dr Jean JOUZEL Pr Edouard BARD Interactions between ocean temperature and isotopic content of Antarctic precipitation are studied with the help of a General Circulation Model (GCM), by distinguishing different geographic sources for the precipitation. The contribution of these sources is estimated for modern as well as glacial (21,000 years ago) climatic conditions. Climatic variations arose from the ocean cooling and the intensification of the meridional gradient of temperature. We have tried different reconstructions of tropical ocean temperatures, which are not well constrained for glacial time, and the source contributions are found quite sensitive to this parameter. For the high latitudes, the isotopic content of precipitation, originating from different sources, are related to the source temperature and its distance to the precipitation site. Contrary to the idea developped by Boyle (1997), a global cooling is not susceptible to bias the classical interpretation of isotopes as paleothermometer, because this cooling is compensated for, in our simulations, by a stronger contribution from the warmer sources. The oceanic field of oxygen-18 is simulated with an ocean GCM, by prescribing at the surface isotopic fluxes derived from the atmospheric GCM. The same fluxes are used to simulate a 'passive' salinity field, consistent with the oxygen-18. The observed features of both fields, as well as their relationships, are well simulated. This modelling allows us to study the sensitivity of their relationships to the surface fluxes, esp. to the continental runoff. The importance of horizontal mixing is estimated by comparing the GCM fields with a box model of the ocean. We also estimate the sensitivity of the deuterium-excess in the Antarctic precipitation to the oceanic temperature, humidity, and isotopic content. L'interaction entre la température des océans et la teneur isotopique des précipitations antarctiques est étudiée à l'aide ... |
author2 |
Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE) Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS) Université de droit, d'économie et des sciences - Aix-Marseille III Bard Edouard |
format |
Doctoral or Postdoctoral Thesis |
author |
Delaygue, Gilles |
author_facet |
Delaygue, Gilles |
author_sort |
Delaygue, Gilles |
title |
Relations entre surface océanique et composition isotopique des précipitations antarctiques : simulation pour différents climats |
title_short |
Relations entre surface océanique et composition isotopique des précipitations antarctiques : simulation pour différents climats |
title_full |
Relations entre surface océanique et composition isotopique des précipitations antarctiques : simulation pour différents climats |
title_fullStr |
Relations entre surface océanique et composition isotopique des précipitations antarctiques : simulation pour différents climats |
title_full_unstemmed |
Relations entre surface océanique et composition isotopique des précipitations antarctiques : simulation pour différents climats |
title_sort |
relations entre surface océanique et composition isotopique des précipitations antarctiques : simulation pour différents climats |
publisher |
HAL CCSD |
publishDate |
2000 |
url |
https://theses.hal.science/tel-00002821 https://theses.hal.science/tel-00002821/document https://theses.hal.science/tel-00002821/file/tel-00002821.pdf |
long_lat |
ENVELOPE(-62.450,-62.450,-64.867,-64.867) |
geographic |
Antarctic The Antarctic Vidal |
geographic_facet |
Antarctic The Antarctic Vidal |
genre |
Antarc* Antarctic Antarctique* |
genre_facet |
Antarc* Antarctic Antarctique* |
op_source |
https://theses.hal.science/tel-00002821 Autre. Université de droit, d'économie et des sciences - Aix-Marseille III, 2000. Français. ⟨NNT : ⟩ |
op_relation |
tel-00002821 https://theses.hal.science/tel-00002821 https://theses.hal.science/tel-00002821/document https://theses.hal.science/tel-00002821/file/tel-00002821.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1785536309183381504 |