Khodri Myriam, Kageyama M., Roche D.M. (2009). Sensitivity of South American tropical climate to last glacial maximum boundary conditions : focus on teleconnections with tropics and extratropics. In :
Vimeux Françoise (ed.), Sylvestre Florence (ed.), Khodri Myriam (ed.). Past climate variability in South America and surrounding regions : from the last glacial maximum to the Holocene. [Dordrecht] : Springer, 213-238. (Developments in Paleoenvironmental Research ; 14). ISBN 978-90-481-2671-2.
Titre du document
Sensitivity of South American tropical climate to last glacial maximum boundary conditions : focus on teleconnections with tropics and extratropics
Année de publication
2009
Type de document
Partie d'ouvrage
Auteurs
Khodri Myriam, Kageyama M., Roche D.M.
In
Vimeux Françoise (ed.), Sylvestre Florence (ed.), Khodri Myriam (ed.)Past climate variability in South America and surrounding regions : from the last glacial maximum to the Holocene
Source
[Dordrecht] : Springer, 2009,
213-238 (Developments in Paleoenvironmental Research ; 14). ISBN 978-90-481-2671-2
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.
Plan de classement
Analyse, évolution des climats [021CLIMAT01]
;
Climatologie / Météorologie [032CLIMET]
;
Evaluation et gestion des ressources en eau [062EVAEAU]
;
Géologie du quaternaire [064GEOQUA]
Description Géographique
BRESIL ; BOLIVIE ; ATLANTIQUE ; PACIFIQUE ; ZONE TROPICALE ; AMERIQUE DU SUD
