Remote Sensing Retrieval of Daily Evapotranspiration over the Heihe River Basin by Integrating the Penman Method

The estimation of evapotranspiration(ET) over heterogeneous land surface over arid and semi-arid region is quite complicated and significant. In this paper, NOAA/AVHRR remote sensing data, NCEP grid data and the meteorological stations data are used to estimate daily ET over the Heihe river basin by integrating Surface Energy Algorithm for Land model [1,2] and the Penman method[3]. As for clear days, Remote sensing model is used to retrieval the instantaneous ET to daily ET [4]. FAO-17 Penman method is also used to estimate the same day´s reference crop ET by NCEP grid data and the meteorological stations data. The relationship between actual ET and the reference crop ET can be used to calculate the actual ET based on the results from FAO-17 Penman method on the cloudy days. These results are validated by observation data and other study in Heihe River Basin.