Análise comparativa dos componentes do saldo de radiação em áreas de pastagem e floresta na Amazônia.

Abstract

The main objective of this study was to analyze in a comparative way the estimate of the surface radiation balance (Rn) through orbital images and measured surface data, as well as the components of Rn, for two types of different vegetable covering (pasture and forest) and also to evaluate the operation of the SEBAL algorithm when applied for an area of tropical-humid atmospheric conditions. This study was accomplished in the state of Rondônia, in the northwest of Brazil. To accomplish the analyses through remote sensing techniques seven orbital images of sensor MODIS/Aqua, four images of TM/Landsat-5 for the application of the algorithm were used and the measured surface data for two micrometeorological towers, being an implanted in pasture area and the other in the forest area. The principal results obtained from the images Modis (low resolution) show maximum and minimum Mean Percentual Error (MPE) coherent for Rn of 3% and 0.02% for the forest area and 10% and 0.7% for the pasture area, respectively. For the TM/Landsat-5 images (high resolution) the values and maximum and minimum MPE were of 16% and 7% for the forest and 12% and 4% for the pasture area, respectively. Those results show the SEBAL as an important and effective tool in environmental and hydrological studies, showing its good application for the obtaining of spatial distribution of surface parameters.