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Oceanic forcing of the late 20th century Sahel drought
Author(s) -
Lu Jian,
Delworth Thomas L.
Publication year - 2005
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 - 10.1029/2005gl023316
Subject(s) - climatology , forcing (mathematics) , environmental science , tropics , tropical atlantic , general circulation model , walker circulation , greenhouse gas , ocean general circulation model , climate model , sea surface temperature , climate change , geology , oceanography , fishery , biology
The Sahel region of Africa underwent a pronounced interdecadal drying trend in the latter half of the 20th century. In order to investigate this drying trend, several ensembles of numerical experiments are conducted using a recently developed atmospheric general circulation model (AM2, developed at NOAA's Geophysical Fluid Dynamics Laboratory). When the model is forced with the time series of observed SSTs and sea ice from 1950 to 2000, it successfully reproduces the observed interdecadal variability of Sahelian rainfall. Additional experiments are used to estimate the separate contributions to Sahel drought from SST anomalies in various ocean basins. In these, SST anomalies are applied only in the tropics, or only in the Atlantic, Indian and Pacific oceans separately. Forcing from the tropical oceans is dominant in driving the Sahelian rainfall trend. The response of Sahel rainfall to a general warming of the tropical oceans suggests a possible link to greenhouse gas‐induced climate change.