Estudo do fluxo convectivo através de simulação de alta resolução.

Abstract

This work studied the convective mass flux associated to shallow cumulus convection with the objective of determining which adjustment was ideal for the parameterization scheme of Souza (1999), through a large-eddy simulation (LES). This study was based on high and low resolution numerical experiments, utilizing the Brazilian Regional Atmospheric Modeling System (BRAMS). An 18-hours integration of the model was performed starting at 06 UTC 23 Janl999 and with three nested grids. The first with a resolution of 32 km, covering the north region of Brazil, the second with a resolution of 4 km and the third with a resolution of 500 m. The three grids are centered on Rondonia state at the coordinates of 11.0 °S and 62.5 °W. In the high-resolution experiment clouds were explicitly modeled. In the lowresolution experiment, the determining of the convective mass flux for the parameterization scheme was done using the principle of convection as a heat engine. The most important conclusion was that, even using high-resolution simulations the surface fluxes are overestimated for the model. However, the shallow convection diurnal cycle is well represented with maximum values above 0,01 kgm s" It was also observed that with an adjustment mat increases the entrainment in the parameterization scheme of Souza, the representation of the convective mass flux was determined within the order of magnitude observed on a variety of studies and confirmed on the high-resolution simulation.