TY  - JOUR
AU  - Xu, Tongren
AU  - Liu, Shaomin
AU  - Xu, Lu
AU  - Chen, Yujie
AU  - Jia, Zhenzhen
AU  - Xu, Ziwei
AU  - Nielson, Jeffrey
PY  - 2015
DA  - 2015//
TI  - Temporal Upscaling and Reconstruction of Thermal Remotely Sensed Instantaneous Evapotranspiration
JO  - Remote Sensing
VL  - 7
IS  - 3
KW  - evapotranspiration;thermal remote sensing;temporal upscaling;continuously daily ET reconstruction;regional ET production
AB  - Currently, thermal remote sensing-based evapotranspiration (ET) models can only calculate instantaneous ET at the time of satellite overpass. Five temporal upscaling methods, namely, constant evaporative fraction (ConEF), corrected ConEF (CorEF), diurnal evaporative fraction (DiEF), constant solar radiation ratio (SolRad), and constant reference evaporative fraction (ConET<sub>r</sub>F), were selected to upscale the instantaneous ET to daily values. Moreover, five temporal reconstruction approaches, namely, data assimilation (ET_EnKF and ET_SCE_UA), surface resistance (ET_SR), reference evapotranspiration (ET_ET<sub>r</sub>F), and harmonic analysis of time series (ET_HANTS), were used to produce continuous daily ET with discrete clear-sky daily ET values. For clear-sky daily ET generation, SolRad and ConET<sub>r</sub>F produced the best estimates. In contrast, ConEF usually underestimated the daily ET. The optimum method, however, was found by combining SolRad and ConET<sub>r</sub>F, which produced the lowest root-mean-square error (RMSE) values. For continuous daily ET production, ET_ET<sub>r</sub>F and ET_SCE_UA performed the best, whereas the ET_SR and ET_HANTS methods had large errors. The annual ET distributions over the Beijing area were calculated with these methods. The spatial ET distributions from ET_ET<sub>r</sub>F and ET_SCE_UA had the same trend as ETWatch products, and had a smaller RMSE when compared with ET observations derived from the water balance method.
ID  - Xu2015
ER  -