Transitions Toward a Midheavy State of Tropical Convection

Abstract This study analyzes the thermodynamic effects of atmospheric vertical motion recorded in satellite observations to investigate the processes behind the evolution of tropical convection. These processes, difficult to observe directly, are diagnosed from satellite retrievals of precipitation ( P ) and atmospheric cloud radiative effect (ACRE) with the aid of a simple theory. It is found that hourly changes of P and ACRE projected onto the P ‐ACRE plane have a tendency of pointing toward a settling point at LP 700 W and ACRE 75 W , corresponding to a state of midheavy ascent. These physically driven transitions are counteracted largely by inverse transitions ascribed mainly to the stochastic effects due to a sample density gradient, except where samples are very few. The net effect of these mutually competing transitions is an evolutionary path qualitatively reminiscent of the known Lagrangian life cycle of a traveling convective system, whereas the P ‐ACRE trajectory stays in the close vicinity of the settling point when spatially averaged over the system.