Abstract: FY-4A is a new-generation geostationary meteorological satellite independently developed by China. The Downward Surface Shortwave Radiation (DSSR) products of FY-4A have broad application prospects in hydrology, ecological research, and energy development and utilization. In this study, the accuracy verification and error analysis of FY-4A DSSR products in Heihe River Basin were carried out based on the ground measurements of 12 radiation sites in the Qilian Mountains integrated observatory network from April to December 2018. The verification results showed that the FY-4A DSSR products fitted well with the field observations. Under clear-sky conditions, the FY-4A DSSR had a strong correlation with the observation data of the ground meteorological stations (r=0.95), with a mean bias error (MBE) of 11.74 W·m^-2 and a root mean square error (RMSE) of 59.43 W·m^-2. Under all-sky conditions, the accuracy was lower than that under clear sky conditions (r=0.82, MBE=75.99 W·m^-2, and RMSE=163.80 W·m^-2). The FY-4A products overestimated DSSR in different months. The correlation between FY-4A DSSR and measurements generally decreased with increasing elevation. With a quantitative analysis of the accuracy of FY-4A DSSR products, our results provided a scientific reference for understanding their quality and application.

Key words: DSSR, accuracy validation, spatial scale, cloud mask.