Radiative-Convective Processes in Regulating Tropical Ocean-Atmosphere

Relationship between sea surface temperature (SST) and cloud/water vapor reveals important information about radiative-climate feedbacks. Many previous studies have found that cloud amount and SST are positively correlated for SST between 28-29.5 C, for SST greater than 29.5 C, cloud amount actually decreases with increasing SST. The breakdown of SST-cloud correlation at 29.5 C was suggested to be related to the formation of localized hot spots with very high SST due to increased solar radiation in regions of strong subsidence forced by convection elsewhere. In this study, the breakdown is related to the radiative cooling in the subsidence regime over the cold pool surrounding the warm pool. We show model and observational evidence that radiative cooling over the cold pool limits the strength of SST-induced tropical circulation. As a result, occurrence of convection is also limited when SST contrast between the warm pool and cold pool is large.