Estimativa da evapotranspiração atual a partir de produtos de sensoriamento remoto usando o método do triângulo

Abstract

The objective of this study was to estimate actual evapotranspiration (ET) using a modeling that associates the surface temperature (Ts) with the Normal Difference Vegetation Index (NDVI), which is known as the method of the triangle or Ts-The triangle method was applied to NDVI and LST products (Land Surface Temperature) of the MODIS/TERRA satellite and to a combination of products NDVI of the SPOT-Vegetation satellite with the LST product of the Meteosat satellite. Results of evapotranspiration were compared with 3 different situations found in the state of Minas Gerais: Sites of conventional meteorological stations of INMET, areas irrigated by central pivots and areas comprising the municipalities. Values of evapotranspiration obtained from MODIS products and SPOT/MSG products were similar for all areas of the study, ranging between 3.09 mm d-1 and 3.35 mm d-1 . The major difference found among estimated actual evapotranspirations was 0.26 mm d-1 when the areas of the municipalities were considered. Actual evapotranspirations by the triangle method based on MODIS products and on the combination of SPOT/MSG products were similar. The sites related to the areas of INMET meteorological stations had the best correlations in the estimates of evapotranspirations, as they correspond to the points that have actual values of meteorological variables of surface used in the models, which allows better adjustments.