Modelagem dos processos meteorológicos de meso e micro-escala na região da floresta de Caxiuanã-Pa

Abstract

Meteorological data and high resolution numerical simulations were used to produce spatial fields in the eastern Amazonia where lies the Forest and the Bay of Caxiuanã near the site of the Project PPBIO, during the COBRA-PARA field experiment. Analysis of the MODIS sensor satellite images show the occurrence of various phenomena such as local cloud streets, formation of convection and an important influence of the interfaces between the forest and water surfaces. The numerical simulations show that the model represented well some meteorological variables for 07 November, 2006, but failed to properly represent the evolution of the atmosphere for to the next day. The model simulates well the temperature of the forest canopy, which is an important variable of interest to other research branches of the PPBIO project. The results show that the Caxiuanã Bay causes significant impact on adjacent meteorological fields mainly through advection by the northeast winds that induce to colder temperatures of the canopy to the west of the bay. Simulations with high resolution with capability of simulating the Large Eddies (LES) show spatial patterns of temperature and humidity aligned with the winds during the daytime, and at nighttime changes are caused mainly by the presence of the bay. The simulation produced a convective system with high resolution showing significant influence of downward gust fronts in the surface fluxes. The sensitivity experiments showed that stronger low level jets caused greater latent heat flux in the early hours of the day. Correlations between the jets and the latent heat fluxes showed that there is a change from negative correlations for the early hours into positive correlations for the afternoon and early evening. This shows that the downdrafts associated gust fronts have important influences on the spatial distribution of surface fluxes. Moreover the replacement of surface water by forest showed an increase in precipitation suggesting that the forest plays a fundamental role in local recycling of water.