Abstract
AbstractSpatial distribution of evapotranspiration (ET) over a complex terrain is estimated using a new approach of the conventional two‐source energy balance (TSEB) model by considering the effect of topography (difference in slope and aspect). We name this approach topography considered two‐source energy balance (T2SEB) model. The novelty of this model is the estimation of incoming shortwave solar radiation considering slope, aspect, altitude, latitude, longitude, and the day of calculation in the TSEB model, so that the new model should have wider applicability than existing models over topographically complex areas. In this study, high spatial resolution Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and meteorological data are used. ET over a complex terrain of Nagoya, Japan, on three different dates, 4 November 2005, 25 May 2004 and 30 October 2003, is estimated using both TSEB and T2SEB models. To validate both models, estimated results are compared with ground observation data at the flux tower site. Moreover, estimated results from TSEB and T2SEB models are compared in five different locations of different topography within the study area. Variation of net radiation absorbed by the surface (Rn) with topographical variables is also studied with the help of scatter plots. Estimated results for all three dates agreed within ±75 W m−2 with calculated values from both models at the flux tower site. TSEB underestimated/overestimated ET in sunlit/shaded areas in hilly areas. The T2SEB model estimated ET in hilly areas better than the TSEB model. Copyright © 2009 John Wiley & Sons, Ltd.
Published Version
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