Mechanisms of Short-Term Sea Surface Temperature Regulation: Observations during TOGA COARE

Abstract

Abstract Analyses of ocean–atmosphere data from Tropical Oceans Global Atmosphere Coupled Ocean–Atmosphere Response Experiment indicate that short-term (weekly to monthly) fluctuations of SST in the western Pacific warm pool are closely linked to the alternation of wet and dry spells driven by the Madden–Julian oscillation (MJO). The dry phase is characterized by increased convection over the Indian Ocean, a prolonged period of atmospheric subsidence, and surface easterlies over the western Pacific warm pool. During this phase, increased surface shortwave radiation and reduced evaporation contribute about equally to the warming of the warm pool. Pronounced diurnal variations in SST observed during the dry phase may be instrumental in leading to the prolonged warming. The dry phase is followed by the wet phase, in which the SST warming trend is arrested and a cooling trend initiated by a reduction in surface shortwave radiation accompanying the buildup of organized convection. Subsequently, the continued c...