Khodri Myriam auteur aut IRD Kageyama M. auteur aut IRD Roche D.M. auteur aut IRD text bookSection eng text/pdf born digital access We explore how the moist deep convection over the Amazonian region responds to glacial forcings compared to the pre-indrustrial climate and how this change might interact with the meridional shift of rainfall over Nordeste, Pacific and Atlantic tropical Oceans. The objective is to assess and investigate the individual contributions of greenhouse gases concentration, ice sheet topography and/or albedo on the hydrological changes over tropical South America and their links to the Hadley and Walker circulations.We employ coupled ocean-atmosphere simulations for the Last Glacial Maximum and sensitivity experiments for each Last Glacial Maximum forcing. We show that the Last Glacial Maximum reduced greenhouse gases alone can explain the observed rainfall changes over tropical South America through the induced increase in tropical and northern extra-tropical dry static stability and altered Hadley circulation. Furthermore, we show that the topography of the North American ice sheet reinforces the equatorward shift of the descending branch of the Hadley cell leading to stronger subsidence and drying over the northern tropics. However, we show that the Laurentide ice sheet has also a significant influence on the simulated enhanced rainfall over Nordeste and Southeastern Brazil via the eastward shift of the Walker circulation, with a mechanism analogous to the atmospheric thermodynamical response to El-Niño conditions. specialized BRESIL BOLIVIE ATLANTIQUE PACIFIQUE ZONE TROPICALE AMERIQUE DU SUD 021CLIMAT01 064GEOQUA 062EVAEAU 032CLIMET Vimeux Françoise ed. edt IRD Sylvestre Florence ed. edt IRD Khodri Myriam ed. edt IRD 14 213-238 [Dordrecht] Springer 2009 14 https://www.documentation.ird.fr/hor/fdi:010082931 10.1007/978-90-481-2672-9_9 978-90-481-2671-2 [F A010082929] https://www.documentation.ird.fr/hor/fdi:010082931 https://www.documentation.ird.fr/intranet/publi/2021-10/010082931.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2021-08-12 2021-10-29 fdi:010082931 fre