Estudo numérico do impacto do realce de fluxo à superfície por rajadas de nuvens convectivas sobre a precipitação.

Abstract

The objective of this work was to study the influence of the flux enhancement by gustiness in a one-month simulation in the rainy season of Northeast Brazil using two grid resolutions. A parameterization scheme for surface-flux enhancement due to gustiness associated with convective clouds was implemented in the BRAMS model. Eight sensitivity experiments were conducted using some of the model’s options of convection parameterization. Results showed a significant impact on the precipitation field. The impact is more pronounced in the region of the Intertropical Convergence Zone (ITCZ) where the synoptic wind is weaker. Grell convective parameterization produced a better simulation of the precipitation amount, compared to Kuo convective parameterization. However, Grell convective parameterization tends to overestimate the observed accumulated precipitation. The experiment using the Kuo scheme showed a negative correlation between flux enhancement and precipitation. On the other hand the experiments with the Grell’s mass-flux convective scheme showed an increase in precipitation as a consequence of the flux surface enhancement.