The effect of freshwater discharge on Tropical Atlantic climate variability First year activity of the 2010 ISSNAF fellowship

Eastern Tropical Atlantic (ETA) collects a huge quantity of fresh water due to discharge from several rivers. The Congo river alone releases every year 1270 km 3 of freshwater into the Gulf of Guinea (GG, Weldeab et al., 2007), which is the secondlargest flow in the world second only to the Amazon River. The aim of this study is to improve our understanding of the climate variability in Africa and Tropical Atlantic, accounting for the forcing represented by the continental freshwater discharge, often neglected in the majority of previous studies. Our main objective is to understand the feedbacks between freshwater discharge and atmospheric and ocean circulation in ETA. The first stage of the study was performed on observations. Results indicate that feedback processes between sea surface temperature (SST), precipitation and river discharge play a role in affecting the interannual variability in the ETA region. Afterwards the same processes were investigated through numerical experiments, in order to evaluate their capability to reproduce the observed processes. Given the large biases affecting coupled general circulation models (GCMs), a restoring of the temperature profile along the coast was necessary to create improved ocean initial condition.