Air-sea interaction in the tropical Atlantic

Sea surface temperatures (SST) in the tropical Atlantic ocean influence weather and climate patterns on the bordering continents and beyond. SST patterns are related to the West African Monsoon, and rainfall and drought over South America. Accurate simulation of oceanic processes with state-of-the-art coupled general circulation models (CGCMs) could enable prediction of societally relevant events, such as drought seasons. However, CGCMs are limited by long-standing biases in the tropical Atlantic, specifically by excessively warm SST in the south-east. In this thesis we investigate sources of variability in the tropical Atlantic, and how their representation in CGCMs lead to biases. We investigate basin wide air-sea interaction pathways as well as local mechanism, which contribute to the build-up of warm SST biases. Our results point to the importance of correct parameterisation of upper ocean vertical mixing for accurate climate model simulations.