East African Rainfall and the Tropical Circulation/Convection on Intraseasonal to Interannual Timescales

Abstract

Abstract It is known that the East African short rains (October–December, OND) have a positive correlation with El Nino–Southern Oscillation (ENSO). A prediction scheme based on sea surface temperature eigenvectors (SST EOFs) including Pacific, Indian, and Atlantic Ocean variability showed skill higher than one based on ENSO alone. First the authors assess the extent to which the large-scale SST predictors correlate with rainfall averaged over smaller subregions of East Africa. Most regions correlate consistently well, though some pockets of lower correlations suggest that interaction with orographic features may modulate the large-scale ENSO and other coupled ocean–atmosphere signals in the region. Next, to evaluate the atmospheric teleconnections giving rise to the SST correlations, the circulation anomalies associated with East African rainfall are investigated using National Centers for Environmental Prediction–National Center for Atmospheric Research reanalysis data and, as a proxy for large-scale tr...