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Sahelian Precipitation Change Induced by SST Increase: The Contrasting Roles of Regional and Larger‐Scale Drivers
Author(s) -
Dixon Ross D.,
Peyrillé Philippe,
Guichard Françoise
Publication year - 2019
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2019gl084872
Subject(s) - precipitation , climatology , rainband , environmental science , troposphere , atmospheric sciences , climate model , monsoon , scale (ratio) , climate change , moisture , zonal and meridional , convection , madden–julian oscillation , sea surface temperature , atmospheric circulation , coupled model intercomparison project , meteorology , geology , geography , oceanography , cartography
Representing the West African Monsoon is a major challenge in climate modeling because of complex mechanisms of interaction across scales. We study the monsoon precipitation response to a 4K increase in sea surface temperatures using an idealized meridional‐vertical (2D) model, which allows separating regional‐ and larger‐scale influences. The 2D simulations reproduce key features of Atmospheric Model Intercomparison Project simulations and indicate that, in response to sea surface temperature increase, large‐scale changes induce a decrease of Sahel precipitation, while regional‐scale mechanisms generate a southward shift of the rainband. Large‐scale changes moisten and warm the free troposphere, while regional circulation changes increase low‐level moisture. Precipitation in the control simulations accounts for much of the variance in precipitation change for both Atmospheric Model Intercomparison Project and 2D simulations. This response is strongly connected to the large‐scale drivers of temperature and moisture, with an additional spread associated with the formulation of the convective parameterization.