INTRASEASONAL AIR-SEA INTERACTION IN THE TROPICAL INDIAN AND PACIFIC OCEANS

The relationships between intraseasonal (periods <100 days) variations of convection, sea surface temperature (SST), surface wind stress, an d surface fluxes of latent heat and radiation in the warm pool of the equatorial Indian and western Pacific Oceans are examined using 7 yr o f gridded outgoing longwave radiation (OLR), SST, and surface stress a nd latent heat flux based on European Centre for Medium-Range Weather Forecasts analyses. In the warm pool region enhanced evaporation, whic h results from enhanced surface westerlies, lags enhanced convection b y similar to 1 week. Intraseasonal SST fluctuations lag decreased evap oration by similar to 1 week and decreased convection (which implies i ncreased insolation) by similar to 2 weeks, suggesting that anomalous latent heat flux and surface insolation drive SST changes on intraseas onal timescale. The relationship between anomalous SST, surface wind s tress and surface fluxes of latent heat and shortwave radiation for th e Madden-Julian oscillation (MJO), which dominates the intraseasonal v ariability of convection and surface winds over the warm pool, is deve loped. Spatially coherent SST anomalies, with amplitude of similar to 113 degrees C, develop in the Indian Ocean and propagate eastward alon g with the large-scale convective anomaly, but with 1/4 cycle lag. The SST anomalies in the Indian Ocean are postulated to be driven predomi nantly by surface insolation anomalies associated with the anomalous l arge-scale convection. The SST anomalies in the western Pacific are po stulated to be driven by a combination of anomalous latent heat flux a nd insolation. The differing behavior in each ocean reflects structura l changes of the MJO as it evolves through its life cycle. Data collec ted during TOGA COARE are used to quantify the role of surface heat fl ux anomalies for driving the SST changes in the western Pacific.