Aplicação do algoritmo SEBAL para a estimativa do saldo de radiação à superfície para diferentes coberturas de solo na região amazônica

Abstract

The surface radiation balance is the balance between radiation that incoming and the radiation radiation outgoing the surface. The same is the one responsible for the regulation of evapotranspiration, sensible heat flux, heat flux in soil and plant photosynthesis. Remote sensing is a tool that has been used for the calculation of the surface radiation balance, because, through it is possible to acquire, process and interpret images and data collected from sensors carried on aircraft or satellites, which capture the interaction between matter and electromagnetic energy. The SEBAL (Surface Energy Balance Algorithm for Land) is an algorithm that uses satellite imagery and a few surface data to estimate the radiative components and has been used widely by the scientific community to estimate several parameters to the surface for different geographical regions. However, there is still little research conducted to evaluate the applicability of this algorithm in regions with high atmospheric humidity. Thus, this study aims at evaluating the use of this algorithm to estimate the radiation balance at the surface, the states of Rondonia and Amazonas, using images of environmental satellite Landsat 5 TM, for the years 2006 to 2010. To carry out the research used data from micrometeorological towers three experimental sites in the LBA, two located in forest regions and in a pasture region, station data and surface EST/UEA, these data were used as input of the algorithm SEBAL and also to validate the estimates. The methodology was divided into stages: georeferencing of images, the algorithm SEBAL to obtain the net radiation at the surface,validating the estimates , andfinally , applicabilityof the algorithm SEBAL to regions with high atmospheric humidity . The results allowed us to evaluate the applicability of the algorithm SEBAL for the Amazon region, indicating that the errors generated at each stage of processing does not imply high errors in the final calculation of the surface radiation balance, since some parameters are larger than the estimates measured data, and other estimates have smaller place so a tradeoff between the errors. Finally, in the absence of instruments to the surface SEBAL algorithm can be used to estimate the various parameters of the surface because it shows errors coming to the errors of measuring devices, even though the parameterization of this algorithm have been developed for semi-arid regions.