A numerical study of the 15 December 1992 TOGA COARE mesoscale convective system

A 16-h real data numerical simulation of the growing and mature stages of the 15 December 1992 TOGA COARE mesoscale convective system is performed. One of the objectives of this study is to obtain a realistic simulation of the lifecycle and to determine the factors that regulated the convective onsets. Another objective is to document the impact of the mesoscale convective system and its embedded mesoscale precipitation features on the atmospheric heat and moisture budgets over the warm pool and the surface energy balance of the underlying ocean. The lifecycle of the mesoscale convective system was characterized by the initiation at 0530 UTC of two entities S₁ and S₂, which underwent development and eventually merged to form a large anvil cloud by 1830 UTC. To obtain a realistic simulation of the lifecycle, improvements to the initial moisture field, the convective and surface flux processes in the model were undertaken.; The lifecycle of the mesoscale convective system was realistically simulated, The growing stage was composed of three convective onsets at 0600, 1100, and 1400 UTC. The onsets were governed by three factors: occurrence of convective available potential energy, large scale ascent and a favorable surface potential temperature dropoff.; The calculated heat and moisture budgets of the mesoscale convective system were characterized by two heating and drying peaks (300 hPa and 925 hPa) with cooling and moistening occurring at midlevels (45–700 hPa).; The surface energy balance was not affected by solar radiation because the system evolved nocturnally. Latent heat flux and the net longwave radiation were the two largest components in the surface energy budget. During the second and third convective onsets, the net longwave radiation remained essentially unchanged but the latent and sensible heat fluxes increased. The enhanced surface fluxes during the onsets increased the residual ocean fluxes, particularly over the region occupied by the third convective onset. (Abstract shortened by UMI.)...