Estimation of Daily Average Shortwave Solar Radiation under Clear-Sky Conditions by the Spatial Downscaling and Temporal Extrapolation of Satellite Products in Mountainous Areas

The downward surface shortwave radiation (DSSR) received by an inclined can be estimated accurately based on the mountain transfer model using digital elevation (DEM) and high-resolution optical remote sensing images. However, it is still challenging to obtain daily average DSSR affected atmosphere local topography in areas. In this study, spatial downscaling temporal extrapolation methods were explored separately estimate under clear-sky conditions Himawari-8, Sentinel-2 satellite products DEM data. upper middle reaches of Heihe River Basin (UM-HRB) Laohugou area Qilian Mountain (LGH) used as study areas because there are many ground observation stations UM-HRB that convenient for studies instantaneous datasets published LHG helpful studies. verification results show both effectively DSSR. A total 3002 measurements from six sites showed 50 m downscaled Himawari-8 10-min 5 km had quite a high correlation with ground-based UM-HRB. coefficient determination (R2) exceeded 0.96. mean bias error (MBE) root-mean-squared (RMSE) about 41.57 W/m2 (or 8.22%) 49.25 9.73%), respectively. fifty-two two indicated extrapolated 10 previously performed well, giving R2, MBE, RMSE values 0.65, 41.06 7.89%) 88.90 17.07%), By comparing estimation LHG, was found although method more finely describe heterogeneity solar complex terrain areas, overall accuracy lower than achieved approach.