Testes dos esquemas de parametrização de cúmulos no modelo BRAMS: sensibilidade à resolução horizontal.

Abstract

This study investigates the sensitivity of the model "Brazilian Regional Atmospheric Modeling System" - BRAMS to the several different kinds of closure associated to the convective parameterization of Grell and to the standard BRAMS convective parameterization, a Kuo-type cumulus parameterization scheme. The purpose is to evaluate which scheme gives BRAMS a better performance in the tropical region. The sensitivity of each closure to horizontal resolution is also studied through experiments with resolutions of 80 and 20 km. The results are based on 96-hour simulations starting at 00 UTC of 20 January 1999 for Rondonia (Brazil). The data are from the Large-Scale Biosphere Atmosphere (LBA), It is shown that the convective parameterizations resulted in a wide variety of rainfall behaviors during the simulation and that the Kuo scheme showed much smaller values of precipitation than those observed. The Arakawa-Schubert closure showed good agreement with the observed values of the surface latent heat flux. Finally the moisture convergence and Grell closures showed the best results (smaller sensitivity) when the model's horizontal resolution varies.