The regional coupled ocean-atmosphere model simulation over Eastern Tropical Africa

Abstract

In this study we examine a 25-year simulation of a Regional Coupled Ocean-Atmosphere Model (RCOM) forced by global atmospheric and ocean reanalysis at the lateral boundaries over eastern equatorial Africa which includes parts of the Great Horn of Africa (GHA). It is a first of its kind use of a RCOM for the region. The model shows several observed features of the regional climate with bimodal peaks in the seasonal cycle interspersed with regions of unimodal peak, significant diurnal and intra-seasonal variations of precipitation especially over Lake Victoria and robust seasonal cycle of the upper western India Ocean. Nonetheless the model shows significant dry bias of seasonal precipitation that is persistent throughout the year, which is also reflected at diurnal and intra-seasonal scales. The mixed layer and thermocline depths are found to be shallower in the model simulation suggesting a far more stratified upper western Indian Ocean than the observations indicate.