Reconstructing last glacial changes in Atlantic meridional overturning rate using marine sediment (231Pa/230Th)
In this thesis, I reconstruct the dynamic of the Atlantic Meridional Overturning Circulation (AMOC) during fast climate changes of the last glacial period. I find that the AMOC upper circulation cell started to slowdown 1420 ± 250 (1σ) and 690 ± 180 (1σ) years before the southward shifts of the Inte...
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Language: | English |
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Online Access: | https://theses.hal.science/tel-01235193 https://theses.hal.science/tel-01235193/document https://theses.hal.science/tel-01235193/file/2014VERS0051.pdf |
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ftuniversailles:oai:HAL:tel-01235193v1 2024-04-28T08:22:33+00:00 Reconstructing last glacial changes in Atlantic meridional overturning rate using marine sediment (231Pa/230Th) Utilisation du rapport (231Pa/230Th) des sédiments marins pour caractériser les changements de circulation océanique lors des variations climatiques de la dernière période glaciaire Burckel, Pierre Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE) Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)) Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA) Université de Versailles-Saint Quentin en Yvelines Claire Waelbroeck Jeanne-Marie Gherardi Sylvain Pichat 2014-11-28 https://theses.hal.science/tel-01235193 https://theses.hal.science/tel-01235193/document https://theses.hal.science/tel-01235193/file/2014VERS0051.pdf en eng HAL CCSD NNT: 2014VERS0051 tel-01235193 https://theses.hal.science/tel-01235193 https://theses.hal.science/tel-01235193/document https://theses.hal.science/tel-01235193/file/2014VERS0051.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-01235193 Oceanography. Université de Versailles-Saint Quentin en Yvelines, 2014. English. ⟨NNT : 2014VERS0051⟩ Atlantic circulation Last glacial period Sedimentary Pa/Th Tropical rain belt Circulation Atlantique Dernière période glaciaire Sédiment Pa/Th [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography info:eu-repo/semantics/doctoralThesis Theses 2014 ftuniversailles 2024-04-04T17:39:46Z In this thesis, I reconstruct the dynamic of the Atlantic Meridional Overturning Circulation (AMOC) during fast climate changes of the last glacial period. I find that the AMOC upper circulation cell started to slowdown 1420 ± 250 (1σ) and 690 ± 180 (1σ) years before the southward shifts of the Inter Tropical Convergence Zone associated with Heinrich Stadial 2 and Heinrich Stadial 4, respectively. I therefore confirm that an AMOC slowdown could be at the origin of the ITCZ shifts that occured during Heinrich Stadials and provide the first precise estimate of the phasing between these two climate variables. Based on these results I propose a mechanism explaining the difference between Heinrich and Dansgaard-Oeschger stadials.Using modeling results, I show that the Atlantic Ocean circulation during periods of higher Greenland temperatures (interstadials) was markedly different from that of the Holocene. Two overturning cells were likely active in the Atlantic Ocean: an upper overturning circulation cell initiated by northern-sourced deep water flowing southward above ~2500 m depth at the equator, and a lower overturning circulation cell initiated by southern sourced deep water flowing northward below ~4000 m depth at the equator. The overturning rate of the upper overturning cell was likely lower than that of present-day North Atlantic Deep Water. At the onset of Heinrich Stadials, the structure of the AMOC significantly changed, and southern-sourced deep-waters likely dominated the equatorial Atlantic Ocean below 1300 m depth. Dans cette thèse, je reconstitue la dynamique de la circulation méridienne de retournement de l’Atlantique (AMOC) au cours des changements climatiques rapides de la dernière période glaciaire. Je trouve ainsi que le ralentissement de la cellule supérieure de l’AMOC commence 1420 ± 250 (1σ) années avant le déplacement vers le sud de l’ITCZ associé au « Heinrich Stadial » 2 et 690 ± 180 (1σ) années avant celui associé au « Heinrich Stadial » 4. Mes résultats confirment donc qu’un ... Doctoral or Postdoctoral Thesis Greenland North Atlantic Deep Water North Atlantic Université de Versailles Saint-Quentin-en-Yvelines: HAL-UVSQ |
institution |
Open Polar |
collection |
Université de Versailles Saint-Quentin-en-Yvelines: HAL-UVSQ |
op_collection_id |
ftuniversailles |
language |
English |
topic |
Atlantic circulation Last glacial period Sedimentary Pa/Th Tropical rain belt Circulation Atlantique Dernière période glaciaire Sédiment Pa/Th [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography |
spellingShingle |
Atlantic circulation Last glacial period Sedimentary Pa/Th Tropical rain belt Circulation Atlantique Dernière période glaciaire Sédiment Pa/Th [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography Burckel, Pierre Reconstructing last glacial changes in Atlantic meridional overturning rate using marine sediment (231Pa/230Th) |
topic_facet |
Atlantic circulation Last glacial period Sedimentary Pa/Th Tropical rain belt Circulation Atlantique Dernière période glaciaire Sédiment Pa/Th [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography |
description |
In this thesis, I reconstruct the dynamic of the Atlantic Meridional Overturning Circulation (AMOC) during fast climate changes of the last glacial period. I find that the AMOC upper circulation cell started to slowdown 1420 ± 250 (1σ) and 690 ± 180 (1σ) years before the southward shifts of the Inter Tropical Convergence Zone associated with Heinrich Stadial 2 and Heinrich Stadial 4, respectively. I therefore confirm that an AMOC slowdown could be at the origin of the ITCZ shifts that occured during Heinrich Stadials and provide the first precise estimate of the phasing between these two climate variables. Based on these results I propose a mechanism explaining the difference between Heinrich and Dansgaard-Oeschger stadials.Using modeling results, I show that the Atlantic Ocean circulation during periods of higher Greenland temperatures (interstadials) was markedly different from that of the Holocene. Two overturning cells were likely active in the Atlantic Ocean: an upper overturning circulation cell initiated by northern-sourced deep water flowing southward above ~2500 m depth at the equator, and a lower overturning circulation cell initiated by southern sourced deep water flowing northward below ~4000 m depth at the equator. The overturning rate of the upper overturning cell was likely lower than that of present-day North Atlantic Deep Water. At the onset of Heinrich Stadials, the structure of the AMOC significantly changed, and southern-sourced deep-waters likely dominated the equatorial Atlantic Ocean below 1300 m depth. Dans cette thèse, je reconstitue la dynamique de la circulation méridienne de retournement de l’Atlantique (AMOC) au cours des changements climatiques rapides de la dernière période glaciaire. Je trouve ainsi que le ralentissement de la cellule supérieure de l’AMOC commence 1420 ± 250 (1σ) années avant le déplacement vers le sud de l’ITCZ associé au « Heinrich Stadial » 2 et 690 ± 180 (1σ) années avant celui associé au « Heinrich Stadial » 4. Mes résultats confirment donc qu’un ... |
author2 |
Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE) Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)) Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA) Université de Versailles-Saint Quentin en Yvelines Claire Waelbroeck Jeanne-Marie Gherardi Sylvain Pichat |
format |
Doctoral or Postdoctoral Thesis |
author |
Burckel, Pierre |
author_facet |
Burckel, Pierre |
author_sort |
Burckel, Pierre |
title |
Reconstructing last glacial changes in Atlantic meridional overturning rate using marine sediment (231Pa/230Th) |
title_short |
Reconstructing last glacial changes in Atlantic meridional overturning rate using marine sediment (231Pa/230Th) |
title_full |
Reconstructing last glacial changes in Atlantic meridional overturning rate using marine sediment (231Pa/230Th) |
title_fullStr |
Reconstructing last glacial changes in Atlantic meridional overturning rate using marine sediment (231Pa/230Th) |
title_full_unstemmed |
Reconstructing last glacial changes in Atlantic meridional overturning rate using marine sediment (231Pa/230Th) |
title_sort |
reconstructing last glacial changes in atlantic meridional overturning rate using marine sediment (231pa/230th) |
publisher |
HAL CCSD |
publishDate |
2014 |
url |
https://theses.hal.science/tel-01235193 https://theses.hal.science/tel-01235193/document https://theses.hal.science/tel-01235193/file/2014VERS0051.pdf |
genre |
Greenland North Atlantic Deep Water North Atlantic |
genre_facet |
Greenland North Atlantic Deep Water North Atlantic |
op_source |
https://theses.hal.science/tel-01235193 Oceanography. Université de Versailles-Saint Quentin en Yvelines, 2014. English. ⟨NNT : 2014VERS0051⟩ |
op_relation |
NNT: 2014VERS0051 tel-01235193 https://theses.hal.science/tel-01235193 https://theses.hal.science/tel-01235193/document https://theses.hal.science/tel-01235193/file/2014VERS0051.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1797584099967238144 |