First high-resolution surface spectral clear-sky ultraviolet radiation dataset across China (1981–2023): development, validation, and variability

Abstract. Solar ultraviolet radiation (UV) plays a fundamental role in the Earth's energy balance, influencing a wide range of processes, including material degradation, biophysical reactions, ecological dynamics, or public health. In this context, the first high-resolution (10×10 km) hourly dataset of surface solar UV under clear-sky conditions over mainland China from 1981 to 2023 is introduced, derived from ERA5 and MERRA2 reanalysis data and a reconstruction based on the SMARTS (Simple Model of the Atmospheric Radiative Transfer of Sunshine) spectral model. Leveraging the SMARTS model's accuracy and capabilities, this dataset provides UV data at 0.5 nm intervals between 280 and 400 nm, offering enhanced granularity for wavelength-specific analysis, thus filling a key gap in high-resolution hourly UV data for China. Validation of the UV dataset against ground observations at 37 stations of the Chinese Ecosystem Research Network (CERN) demonstrates strong performance, with a correlation coefficient (R), root mean square error (RMSE), and mean bias error (MBE) of 0.919, 5.07 W m−2 and −0.07 W m−2, respectively. Compared with the Clouds and the Earth's Radiant Energy System (CERES) UV product, this dataset offers higher spatial and temporal resolution as well as higher accuracy in comparison with observations, thus enhancing data quality for a wide range of applications. The spatial and temporal distribution of clear-sky UV radiation exhibits distinct regional and seasonal variations, with higher values in the west and south, and lower values in the east and north. Over the past 43 years, the annual mean clear-sky broadband UV radiation averaged over China was 20.05 W m−2, showing a slightly increasing trend (+0.0237 W m−2 yr−1). This dataset is now available at https://doi.org/10.6084/m9.figshare.28234298 (Qi et al., 2025), offering a valuable resource for addressing regional challenges related to UV radiation.