Intraseasonal variability in the southwestern and central tropical Atlantic Ocean
Various kinds of intraseasonal variability (ISV) exist in the oceans which have recently been observed in many locations surrounding the tropical Atlantic Ocean. In this study, current measurements from mooring sites close to the western boundary in the southern hemisphere and at the equator in the central basin are analyzed which reveal signals at intraseasonal periods. Basinwide altimeter measurements as well as results from two numerical model simulations with varying surface wind forcing are applied in order to clarify the dynamic processes essential for the observed intraseasonal signals. It is shown that in the tropical Atlantic two key processes lead to the generation of fluctuative energy at intraseasonal periods: barotropic and baroclinic instability.