Deep cloud clusters in the tropics

Abstract

The factors which govern the existence of deep cloud clusters (DCC) in both continental and oceanic regions are examined. It is shown that the necessary condition for the existence of DCC in continental (oceanic) regions is that the surface moist static energy must be above 350 kJ/kg (340 kJ/kg). The difference in the moist static energy threshold between the oceans and the continents has been attributed to the differences in the vertical profile of moist static energy. If the mean moist static energy of the troposphere from surface to 400 millibar is used (instead of the surface moist static energy) then the threshold for the existence of DCC is 335 kJ/kg and is the same for both oceans and continents. The total energy convergence in the troposphere has been shown to be an important constraint which could reduce the presence of DCC in the warmest oceans or continent. It is shown that there can be several routes to desertification when vegetation is removed from a continental region.