Estimation of daily evapotranspiration in the Yellow River Basin by using MODIS data

It is significant and necessary to estimate regional evapotranspiration (ET) in the hydrology and water resource research. Remotely sensed data conjunct with ground observed data supply us a convenient approach to estimate ET. A Surface Energy Balance System (SEBS) model was used to estimate daily evapotranspiration in the Yellow River basin, China. SEBS is an aerodynamics-resistance model, which is based on the surface energy balance index (SEBI) estimated from radiometric surface temperature, and it calculates the latent heat flux or ET as the residual of net solar radiation, soil heat flux, and sensible heat flux. The MODIS data including surface temperature, NDVI, emissivity and albedo were used. SEBS also requires wind speed, potential temperature and humidity of air at an appropriate reference height. The reference height was taken as being the height of the planetary boundary layer (PBL) and the data used were generated and interpolated from observed meteorological data and NCEP/NCAR Reanalysis data. The results show that the SEBS model and MODIS data can he effectively used to estimate daily ET.