Evaluating European ECOSTRESS Hub Evapotranspiration Products Retrieved
from Three Structurally Contrasting SEB Models over Europe
Abstract
The ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station
(ECOSTRESS) is a scientific mission that collects high spatio-temporal
resolution (~70 m, 1-5 days average revisit time)
thermal images since its launch on 29 June 2018. As a predecessor of
future missions, one of the main objectives of ECOSTRESS is to retrieve
and understand the spatio-temporal variations in terrestrial
evapotranspiration (ET) and its responses to soil water availability. In
the European ECOSTRESS Hub (EEH), by taking advantage of land surface
temperature retrievals, we generated ECOSTRESS ET products over Europe
and Africa using three structurally contrasting models, namely Surface
Energy Balance System (SEBS) and Two Source Energy Balance (TSEB)
parametric models, as well as the non-parametric Surface Temperature
Initiated Closure (STIC) model. A comprehensive evaluation of the EEH ET
products was conducted with respect to flux measurements from 19 eddy
covariance sites over 6 different biomes with diverse aridity levels.
Results revealed comparable performances of STIC and SEBS (RMSE of
~70 W m-2). However, the relatively
complex TSEB model produced a higher RMSE of ~90 W
m-2. Comparison between STIC ET estimate and the
operational ECOSTRESS ET product from NASA PT-JPL model showed a
difference in RMSE between the two ET products around 50 W
m-2. Substantial overestimation (>80 W
m-2) was noted in PT-JPL ET estimates over shrublands
and savannas presumably due to the weak constraint of LST in the model.
Overall, the EEH is promising to serve as a support to the Land Surface
Temperature Monitoring (LSTM) mission.