THE INFLUENCE OF THE MADDEN-JULIAN OSCILLATION ON OCEAN SURFACE HEAT FLUXES AND SEA-SURFACE TEMPERATURE

The Madden-Julian oscillation (MJO) involves pronounced variations in convection and large-scale circulation throughout the tropical troposp here. In addition, the MJO is also related to dynamic and thermodynami c variability near the surface and the upper ocean. This study uses ob servational data to characterize the changes in surface heat fluxes an d sea surface temperature (SST) during the life cycle of the MJO. Vari ations in convective activity are described with outgoing longwave rad iation (OLR) during the period January 1985 through September 1994. In ternational Satellite Cloud Climatology Project data (January 1985-Apr il 1991) and European Centre for Medium-Range Weather Forecasts surfac e analyses (January 1985-December 1994) are used to derive surface flu xes of net shortwave radiation (SW), latent heat (E), their difference (Q = SW - E), and SST. The spatial patterns of OLR, SW, E, Q, and SST anomalies reveal that the region of positive OLR anomalies that prece de the occurrence of enhanced convection is associated with positive S W and negative E anomalies, which result in positive Q anomalies. The prevailing conditions in the region of positive Q anomalies favor the development of positive SST anomalies, which lead to variations of enh anced convection. In contrast the region of negative OLR anomalies is associated with negative SW and positive E anomalies. These conditions induce negative Q anomalies, which favor the formation of negative SS T anomalies. The above results suggest a possible feedback between the oscillation and intraseasonal variations in SST and this may be an im portant mechanism for numerical simulations:of the life cycle of the M JO.