Assessment of the Himawari-9 downward surface shortwave radiation (DSSR) product in China under different cloud and aerosol scenarios

Advanced Himawari Imager (AHI) aboard Himawari-8/9 can provide downward surface shortwave radiation (DSSR) over China with 5 km and a high temporal resolution of 10 min. In order to assess the applicability of DSSR from satellites for different weather conditions, the performance of Himawari-9 DSSR product in China is evaluated using ground measurements from stations of China Meteorological Administration (CMA) in this study. The quality of the DSSR product will be assessed under different cloud optical depth (COD) as well as different aerosol optical depth (AOD) scenarios. The overall comparison of hourly AHI DSSR and ground DSSR shows a high correlation coefficient (R = 0.88, RMSE = 143.13 W/m²), 84 % of the stations exhibit an R exceeding 0.8, and 70 % show an RPE below 0.4. However, the satellite observational discrepancies grow as cloud cover and aerosol level intensify, with the correlation coefficients dipping from 0.92 (clear sky) to the lowest values of 0.31 (COD > 50) and slightly decreasing from 0.92 (0 ≤ AOD ≤ 0.1) to 0.82 (AOD > 2), respectively. This study offers a scientific foundation for utilizing the DSSR product of Himawari-9, and highlights the limitations of the data quality under specific weather conditions.