Merging High-Resolution Satellite Surface Radiation Data with Meteorological Sunshine Duration Observations over China from 1983 to 2017.

Surface solar radiation (R_s) is essential to climate studies. Thanks to long-term records from the Advanced Very High-Resolution Radiometers (AVHRR), the recent release of International Satellite Cloud Climatology Project (ISCCP) HXG cloud products provide a promising opportunity for building long-term R_s data with high resolutions (3 h and 10 km). In this study, we compare three satellite R_s products based on AVHRR cloud products over China from 1983 to 2017 with direct observations of R_s and sunshine duration (SunDu)-derived R_s. The results show that SunDu-derived R_s have higher accuracy than the direct observed R_s at time scales of a month or longer by comparing with the satellite R_s products. SunDu-derived R_s is available from the 1960s at more than 2000 stations over China, which provides reliable decadal estimations of R_s. However, the three AVHRR-based satellite R_s products have significant biases in quantifying the trend of R_s from 1983 to 2016 (−4.28 W/m²/decade to 2.56 W/m²/decade) due to inhomogeneity in satellite cloud products and the lack of information on atmospheric aerosol optical depth. To adjust the inhomogeneity of the satellite R_s products, we propose a geographically weighted regression fusion method (HGWR) to merge ISCCP-HXG R_s with SunDu-derived R_s. The merged R_s product over China from 1983 to 2017 with a spatial resolution of 10 km produces nearly the same trend as that of the SunDu-derived R_s. This study makes a first attempt to adjust the inhomogeneity of satellite R_s products and provides the merged high-resolution R_s product from 1983 to 2017 over China, which can be downloaded freely. [ABSTRACT FROM AUTHOR]