Variations of monsoon systems during the Holocene in the IPSL model

• Main Author: Marzin, Charline
• Other Authors: 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 Pierre et Marie Curie - Paris VI, Pascale Braconnot
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2011
• Subjects: Mousson; Holocène; Paléoclimats; Paramètres orbitaux; Inde; Afrique; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Ice Sheet; North Atlantic
• Online Access: https://theses.hal.science/tel-00825378; https://theses.hal.science/tel-00825378/document; https://theses.hal.science/tel-00825378/file/these_Charline_Marzin.pdf

Numerous climate indicators and modelling experiments show the influence of orbital parameters on past variations of Asian and African monsoons. In particular, the monsoon precipitation and circulation were amplified at the beginning of the Holocene, when the insolation received at the top of the atmosphere was maximum during boreal summer. This study analyses the variations of monsoons systems over the Sahel, India and East-Asia at the beginning of the Holocene (9.5 kyr BP) and at the Mid-Holocene (6 kyr BP) with the IPSL-CM4 coupled model. This work highlights the role of precession of equinoxes and the influence of several climate feedbacks in modifying the seasonality and the relative amplification of monsoon systems throughout the Holocene. The amplitude and the phase of the mechanisms by which monsoons respond to insolation changes vary over India and Africa. This thesis also discusses the possible role of teleconnections between monsoons and the mid-latitudes. Sensitivity experiments to the reminiscent ice sheet at the beginning of the Holocene and to the freshwater flux due to ice melting in the North Atlantic show different responses of the Asian and African systems to these forcings. To complement these experiments, the impact of freshwater flux in the North Atlantic on monsoon systems is compared for several past (Eemian, Last Glacial Maximum, Early Holocene, Mid-Holocene), present and future periods. The results of the modelling experiments at the Holocene and at the Last Glacial Maximum have been compared with paleoclimatic marine records in the Indian Ocean De nombreux indicateurs climatiques et expériences de modélisation montrent l'influence des paramètres de l'orbite terrestre sur les variations passées des systèmes de mousson en Asie et en Afrique. En particulier, les moussons sont amplifiées au début de l'Holocène, période de maximum d'insolation au sommet de l'atmosphère pendant l'été boréal. Ce travail s'intéresse aux variations des systèmes de mousson du Sahel, d'Inde et d'Asie du sud-est ...