Ocean Warming and Late-Twentieth-Century Sahel Drought and Recovery
Open Access
- 1 August 2008
- journal article
- Published by American Meteorological Society in Journal of Climate
- Vol. 21 (15), 3797-3814
- https://doi.org/10.1175/2008jcli2055.1
Abstract
The influences of decadal Indian and Atlantic Ocean SST anomalies on late-twentieth-century Sahel precipitation variability are investigated. The results of this regional modeling study show that the primary causes of the 1980s Sahel drought are divergence and anomalous anticyclonic circulation, which are associated with Indian Ocean warming. The easterly branch of this circulation drives moisture away from the Sahel. By competing for the available moisture, concurrent tropical Atlantic Ocean warming enhanced the areal coverage of the drought. The modeled partial recovery of the precipitation in the 1990s simulations is mainly related to the warming of the northern tropical Atlantic Ocean and an associated cyclonic circulation that supplies the Sahel with moisture. Because of the changes in the scale and distribution of the forcing, the divergence associated with the continued Indian Ocean warming during the 1990s was located over the tropical Atlantic, contributing to the recovery over the Sahel. In general, the influence of SSTs on Sahel precipitation is related to their modulation of the easterly flow and the associated moisture transport. Precipitation anomalies are further enhanced by the circulation patterns associated with local convergence anomalies. These convergence anomalies and circulation patterns are sensitive to the scale and distribution of the SST anomalies and the moisture.Keywords
This publication has 24 references indexed in Scilit:
- Dynamics of the West African Monsoon JumpJournal of Climate, 2007
- Oceanic forcing of the late 20th century Sahel droughtGeophysical Research Letters, 2005
- On the linear response of tropical African climate to SST changes deduced from regional climate model simulationsTheoretical and Applied Climatology, 2005
- An improved method of constructing a database of monthly climate observations and associated high-resolution gridsInternational Journal of Climatology, 2005
- The impact of decadal‐scale Indian Ocean sea surface temperature anomalies on Sahelian rainfall and the North Atlantic OscillationGeophysical Research Letters, 2003
- Oceanic Forcing of Sahel Rainfall on Interannual to Interdecadal Time ScalesScience, 2003
- Enhancement of Interdecadal Climate Variability in the Sahel by Vegetation InteractionScience, 1999
- Analyses of Global Monthly Precipitation Using Gauge Observations, Satellite Estimates, and Numerical Model PredictionsJournal of Climate, 1996
- The NCEP/NCAR 40-Year Reanalysis ProjectBulletin of the American Meteorological Society, 1996
- A One-Dimensional Entraining/Detraining Plume Model and Its Application in Convective ParameterizationJournal of the Atmospheric Sciences, 1990