Air-Sea Interactions at Intraseasonal timescales over the Indian Ocean Region

A potentially important process for the predictability in the tropics is the interaction between the SST and large-scale perturbations of the convective activity at intraseasonal timescales. Above the Indian Ocean, large perturbations of the SST, associated to intraseasonal oscillations of the convection, are observed all along the year. We use the OGCM ORCA, forced by observations (satellite and meteorological analyses) of surface parameters, to study the physical sources of the perturbation of the thermal structure of the ocean mixed layer over different regions of the tropical Indian Ocean. Also, using the LMD/Z AGCM we study the improvement of the representation of intraseasonal oscillations while using high frequency (day-to-day) variation of the SST field instead of a smooth seasonal variation of the SST structure. Implications of these preliminary results for the tropical seasonal predictability are discussed.