Reconstruction of remotely sensed daily evapotranspiration data in cloudy-sky conditions

The unavailability of thermal infrared satellite observations in cloudy conditions has limited the spatial distribution and temporal coverage remotely sensed evapotranspiration (ET) data. As a result, number approaches have been developed to reconstruct daily ET data cloudy-sky conditions. Despite wide application these approaches, no work conducted compare their performance over variety climatic vegetative In this study, three commonly used reconstruction namely, reference fraction (EToF), land surface temperature (LSTR), variational assimilation (VDA) are obtain under abovementioned applied Heihe River Basin (HRB) northwest China during growing season 2015. HRB covers an area approximately 1,432,000 km2 contains various covers. large aperture scintillometer (LAS) eddy covariance (EC) measurements evaluate methods grassland, cropland, riparian forest sites HRB. results show that EToF approach underestimates at grassland days because negatively biased ET/ETo (where ETo is evapotranspiration) clear-sky days. VDA overestimates overpredicted evaporative values. LSTR due under-reconstructed LST day. mean absolute percentage difference (MAPD) root square error (RMSE) statistical metrics (MAPD = 43.1% RMSE 1.3 mm/day) 46.7% 1.4 slightly outperform 46.6% 1.5 mm/day). RMSEs reconstructed values by EToF, VDA, increase respectively from 1.6, 1.2, (mm/day) 2.2, 1.9, 2.0 as consecutive increases 1 3. These outcomes suggest synergistic use space-borne microwave into remote sensing-based can improve