ORIGINE ET IMPACT CLIMATIQUE D'UN CHANGEMENT DE CIRCULATION THERMOHALINE AU COURS DES PROCHAINS SIECLES DANS LE MODELE IPSL-CM4

• Main Author: Swingedouw, Didier
• Other Authors: Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique (CERFACS), Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique - CERFACS (CERFACS), Université Pierre et Marie Curie - Paris VI, Pascale Braconnot et Pascale Delecluse
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2006
• Subjects: Ocean dynamics; climate; thermohaline circulation; ocean-atmosphere interactions; climate sensitivity; Dynamique de l'océan; climat; circulation thermohaline; interactions océan-atmosphère; sensibilité climatique; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Greenland; glacier; North Atlantic; Sea ice
• Online Access: https://theses.hal.science/tel-00451249; https://theses.hal.science/tel-00451249/document; https://theses.hal.science/tel-00451249/file/Swingedouw_.pdf

The thermohaline circulation (THC) strongly inuences the climate of the North Atlantic. The warming caused by the release of anthropic CO2 risks to affect this oceanic circulation and then the climate. In this thesis we point to evaluate this risk and to understand the climatic impact of the THC in the future thanks to the tri-dimensional ocean-atmosphere-sea-ice-land IPSL-CM4 coupled model. In a rst part we have done a survey of the principal theories and knowledges concerning the THC. We have then validated the pertinence of IPSL-CM4 to lead our study. The role of the salt has appeared primordial for the dynamics of the THC. Then, we have evaluated the sensitivity of the THC to the global fresh water forcing of the ocean. Different sensitivities of the convection sites of the North Atlantic, related to salinity transport process, have been revealed in IPSL-CM4. We have then analysed some scenario simulations for next centuries. It has appeared a signicant diminution of the THC in those simulations, which is strongly magnied if the melting of Greenland is taken in account. The analysis of several scenarios taking into account or not this glacier melting has permitted to isolate in an original manner the role played by THC feedbacks. Last, the effect of the THC on the climate has been quantied in IPSL-CM4. It appears to be more slight that the global warming, even locally on Europe. The explanation of the mechanisms at the origin of the inuence of the THC on climate has also been claried. The impact of the THC on the oceanic carbon uptake in the ocean has been lastly evaluated, and appears to be very small on 140 years. This study thus gives a clear vision of the role of the THC on the climate and its possible future. La circulation thermohaline (THC) influe fortement sur le climat de l'Atlantique Nord. Le réchauffement climatique causé par les émissions anthropiques de CO2 risque d'altérer cette circulation océanique et donc le climat. Dans cette thèse nous proposons d'évaluer ce risque et de comprendre ...