Sensoriamento remoto aplicado ao estudo do balanço de energia em áreas de floresta e pastagem em Rondônia no Brasil.

Abstract

This study aimed to estimate the components of the energy balance at the surface and quantify the impact of the replacement of forest by pasture areas in the flow of energy in the state of Rondônia, Brazil. We used the algorithm METRIC (Mapping Evapotranspiration at High Resolution and with Internalized Calibration) and ten MODIS images that are aboard the Terra satellite was used meteorological elements available in Deployed microteorológicas towers in forest and grassland sites , such as wind speed and air temperature. The results showed a good agreement between the values estimated by the satellite images with the measured data in micrometeorological towers to the net radiation Rn, with an average percentage error of 13 % for the region of grasslands and 9% for the forest area. It was found also that during the study period there was an increase in sensible heat flux and soil heat , and a decrease in net radiation , the latent heat flux and hence the instantaneous hourly evapotranspiration, which affects considerably the local atmosphere , making it warmer and drier . The conversion of forests to pasture caused significant changes in the radiation balance. The increase in albedo values, the long-wave radiation emitted to the atmosphere and net longwave radiation, resulted in a reduction of net radiation and evapotranspiration.