Proposal of the Regional Complementary Model for Estimating Actual Evapotranspiration Using Remotely Sensed Data

Brutsaert (1979, 1982) suggested a method for the complementary model taking atmospheric stability into account on the basis of the Monin-Obukhov similarity theory. Katul and Parlange (1992a, 1992b) and the authors (1993) independent ly published the papers on the estimation of latent and sensible heat fluxes including the effects of the atmospheric stabil ity. Parlange and Katul (1992c) actually estimated the latent heat flux using the complementary model suggested by Brutsaert. This paper describes a regional complementary model utilizing the remotely sensed data to estimate the actual evapotranspiration in broad areas. The proposed method is summarized as follows. First, the new method estimated the regional air temperature in the atmospheric surface boundary layer using meteoro logical routine data and surface temperatures derived from the Landsat TM data. Secondly, the authors applied the esti mated air temperatures on the evaluation of the regionally distributed drying power of the air in the Penman potential evaporation composing the complementary relationship. The authors' method enables the complementary model to esti mate the distribution of the actual evapotranspiration in regional areas. The values of the latent heat flux obtained by the proposed method have almost coincided with those by the other method already reported by the authors (1994, 1996).