A global terrestrial evapotranspiration product based on the three-Temperature model with fewer input parameters and no calibration requirement

Abstract

Accurate global terrestrial evapotranspiration (ET) estimation is essential to better understand Earth's energy and water cycles. Although several global ET products exist, recent studies indicate that ET estimates exhibit high uncertainty. With the increasing trend of extreme climate hazards (e.g., droughts and heat waves), accurate ET estimation under extreme conditions remains challenging. To overcome these challenges, we used 3g h and 0.25g Global Land Data Assimilation System (GLDAS) datasets (net radiation, land surface temperature (LST), and air temperature) and a three-Temperature (3T) model, without resistance and parameter calibration, in global terrestrial ET product development. The results demonstrated that the 3T model-based ET product agreed well with both global eddy covariance (EC) observations at daily (root mean square error (RMSE)g Combining double low lineg 1.1g mmg d-1, NCombining double low line294058) and monthly (RMSE Combining double low lineg 24.9g mmg month-1, NCombining double low line9632) scales and basin-scale water balance observations (RMSEg Combining double low lineg 116.0g mmg yr-1, NCombining double low line34). The 3T model-based global terrestrial ET product was comparable to other common ET products, i.e., MOD16, P-LSH, PML, GLEAM, GLDAS, and Fluxcom, retrieved from various models, but the 3T model performed better under extreme weather conditions in croplands than did the GLDAS, attaining 9.0g %-20g % RMSE reduction. The proposed daily and 0.25g ET product covering the period of 2001-2020 could provide periodic and large-scale information to support water-cycle-related studies. The dataset is freely available at the Science Data Bank (10.57760/sciencedb.o00014.00001, Xiong et al., 2022).