KELVIN WAVES ACTIVITY IN THE EASTERN TROPICAL ATLANTIC

摘要

Tropical Atlantic intraseasonal variability is investigated in the framework of propagation of sea surface height anomalies along the equator and the West-African coastlines. We present a climatological analysis of the observed intraseasonal equatorial Kelvin wave activity and its coastally trapped extension signals. A OGCM simulation is used to provide the subsurface activity. The analysis focuses then on the wind activity that trigger the signal in the west equator and modulates it along the whole trajectories. An about two months periodicity is found for the Kelvin wave signals and the winter season presents more activity The equatorial Kelvin wave propagates eastward along the equator until the African coast where the wave splits and travels polewards, coastally trapped. The propagation is clear until about 12 degree of latitude North and South where it encounters the oceanic fronts of the Mauritanian and Benguela upwelling regions. Beyond, local wind effects become predominant and control largely the ssha.