The suppression of deep convection in the southwest Caribbean

Abstract

The following results were obtained from radiosondes released from the ship Justo Sierra in July of 2001 as part of the ECAC 3 (Climate Experiment in the Warm Pools of the Americas) campaign. The region of interest for our study was the southwestern Caribbean (off the coast of Nicaragua).

The atmospheric conditions present at the time of the experiment (strong winds, high sea surface temperatures) should have been favorable for the development of deep convection but this is not what our observations revealed. A possible explanation for this phenomenon is the entrainment of dry air. In steady state the growth of the boundary layer is controlled by the subsidence of the overlying air. We applied a steady state balance model for the moist entropy in the boundary layer and found the subsidence necessary to sustain such an extreme case. Our results showed that the downward velocities for this case are considerable when compared with normal radiatively induced subsidence velocities.