Implementação de um esquema de convecção rasa baseado em fechamento de primeira ordem no BRAMS.

Abstract

In this work, a parameterization scheme for shallow-cumulus convection is implemented in the BRAMS model. The scheme is based on a first-order closure for turbulence, and the main focus of the study is the nocturnal convection. We performed several experiments varying both the model’s grid resolution and the deep-convection parameterization type in order to test the sensitivity of the new scheme to model resolution and deep-convection. The model was run for a 96-hours period, starting at 00:00 UTC of 23 Mar 2004. Results show a more evident impact in the first three day of simulation. Furthermore the new shallow-convection scheme showed more sensitivity to the deep-convection scheme type than to the model resolution. In general the impact of the nocturnal shallow convection was more remarkable when the Grell scheme was used, in comparison with the Kuo-type scheme. On the other hand, the results suggest that the parameterization shows low sensitivity to the resolution in the 20 to 50 km interval.