Evapotranspiration Estimation in Tropical Monsoon Regions Using Improved ETMonitor Algorithm

Thailand is characterized by typical tropical monsoon climate, and is suffering from serious water related problems, including seasonal drought and flooding. It is critical to study the spatiotemporal pattern of evapotranspiration (ET) in Thailand to support the local water resource management. In this study, daily ET was estimated over Thailand by ETMonitor, a process based model, based on mainly satellite earth observation datasets. The original ETMonitor is improved by combing land surface temperature -based method to calibrate the algorithm regionally by parameterizing the constrain of soil moisture. Good agreements were found between the estimated daily ET and flux tower observation with root mean square error from 1.06 to 1.21 mm d
^-1
. The Chi and Mun river basins, located in the Northeast Thailand, were selected to analyze the ET spatiotemporal pattern. The results indicate that the ET had large seasonal variability in these two basins, which is largely influenced by the monsoon climate.