P30     Relationship between Indian Ocean SSTs and the East African Short Rains.

Liu, Weiran, Kerry H. Cook and Edward K. Vizy, Department of Geological Sciences, Jackson School of Geosciences, The University of Texas

The purpose of this study is to identify sub-regions of Indian Ocean SSTs that influence the East African short rains, and to investigate the mechanisms of that influence. The East African short rains are positively correlated with SSTAs in western and central Indian Ocean and negatively correlated with eastern Indian Ocean SSTAs. While SSTAs in the western and central Indian Ocean are highly correlated, eastern Indian Ocean SSTAs are independent. WRF is used at 30-km resolution to generate 5 20-year ensembles representing a control climate and idealized SSTA simulations. Positive western Indian Ocean SSTAs are associated with significantly increased short rains over 95% of the East Africa domain while only 30% of the East Africa domain is responsive to central and eastern Indian Ocean SSTAs. The mechanisms of this influence are interpreted using moisture budget and moist static energy analyses, with reference to Kelvin and Rossby wave generations in the Gill model. Moisture convergence anomalies dominate the change in precipitation in each case, and moist static stability anomalies are dominated by the changes in low-level moisture. The responses in the western and eastern parts of equatorial East Africa domain are fundamentally different due to the presence of complex topography.