Variabilidad del Atlántico tropicalinteracciones océano-atmósfera e impactos en el clima

Abstract

This study deals with the Tropical Atlantic Variability (TAV), in particular with the role of the ocean-atmosphere interactions: 1) characterizes the Sea Surface Temperature (SST) patterns over the Tropical Atlantic (TA) with a preciting value, which covary with the summer West African rainfall and the winter European precipitation. 2) explains the ocean-atmosphere interactions which are implied in the time-evolution of the modes and evalues the oceanic adjustment throughout oceanic waves. The leading SST pattern which covaries with the winter European precipitation has a center of action over the Subtropical Northe Atlantic (SNA) and has a predictive skill for the precipitation over Iberian Peninsula and North of Africa. The SST over SNA is led by the surface turbulent heat fluxes and by the upwelling processes over the Mauritanian/Senegal system. The leading SST pattern, which covaries with the summer rainfall over West Africa, relates the Equatorial Mode (EM) to the rainfalll over the Gulf of Guinea. The EM has its origin over the Angola/Benguela upwelling system and evolves through oceanic Rossby waves and is damped by latent heat fluxes and a oceanic equatorial Kelvin wave. The EM could be leading a Pacific La Niña six months in advance. There is Kelvin wave activity over the TA with a predominant period of 50 days. These waves travel eastward equatorially trapped from the western equator up to the african coast, from where they propagate poleward coastally trapped as far as 12º latitude. A mechanism is proposed to explain the Kelvin waves generation that implies Ekman pumping InterTropical Convergence Zone shift-induced anomalies. This work highlights the importance of the African coastal upwelling systems and the oceanic waves activity in the TAV.