Development and evaluation of a simple hydrologically based model for terrestrial evapotranspiration simulations

Following the scheme of the groundwater-soil-plant-atmosphere continuum (GSPAC), a simple process-based model (SiTH; Simple Terrestrial Hydrosphere) was developed to estimate the dynamics of terrestrial evapotranspiration (ET) at the daily step. The input data include net radiation, air temperature, precipitation, leaf area index, vegetation type and soil data, most of which are readily available. Locally, the model performed well in simulating the dynamics of ET and soil moisture over selected FLUXNET sites. Globally, the daily 0.25 degrees ET and groundwater table depth estimations in year 2005 were determined using available gridded datasets. The spatial pattern was reasonable and the range of values corresponded well with other global ET and groundwater table depth products. In future studies, we will produce a long-term daily 0.25 degrees global ET and groundwater table depth products that spans from 1984 to present by using different input datasets.