Mapping evapotranspiration using MODIS and GRACE data

The MODerate resolution Imaging Spectroradiometer (MODIS) data were widely used to estimate land surface evapotranspiration (ET). However, the MODIS ET estimates may not close the land surface water budget. A MODIS ET estimation approach was implemented in the Yellow River Basin of China from 2002 to 2004. The MODIS ET estimates were compared with the estimates from a water budget approach that inferred ET from the Gravity Recovery and Climate Experiment (GRACE) water storage variations, precipitation and streamflow observations. The results showed that the MODIS ET estimates had systematic bias in the monthly mean. The ET estimates from the water budget approach were used to adjust the MODIS ET estimates. The adjusted MODIS ET data have the MODIS spatiotemporal resolution and can fit better with the land surface water budget. It suggests that the MODIS ET estimates may be improved by the use of the GRACE water storage variations.