Balanço de energia à superfície em caatinga: estudo observacional e de simulação com o BRAMS.

Abstract

In this work, we analyzed the aspects of the energy balance at the surface, with emphasis on the latent and sensitive heat flux. The used data was observed in the location of Petrolina (a city in the state of Pernambuco, Brazil), and simulations were made using the Brazilian Regional Atmospheric Modeling System — BRAMS, for two domains of 50 by 50 points of grid with resolutions of 30 and 5 km, centered in the coordinates 9°S and 40.5°W. Three periods of five days in relatively dry soil, and in wet soil were chosen for the investigation. The analyses were limited to the higher resolution. The largest limitations in the simulations were the impossibility of using the moisture of the soil in a non-homogenous way, and the absence of micrometeorological measurements for a raining period. The results proved that the most part of available energy is used as latent heat flux for wet soil, and as sensitive heat flux for dry soil. The observed values of the latent and sensitive heat fluxes were well represented in the simulations. In the simulations for relatively dry soil, we observed indications of the physiographic effects in the region, with prominence for the Sobradinho Dam, the São Francisco River, and the orography. A more intense evaporation was observed in the Sobradinho dam and along the São Francisco River. Local circulations of the lacustre type and the mountain-valley type were detected by the advection fields of moisture and temperature analyzed.