PM2.5 plays a key role in the solar radiation budget and air quality assessments, but observations and historical data are relatively rare for Beijing. Based on the synchronous monitoring of PM2.5 and broadband solar radiation (Rs), a logarithmic function was developed to describe the quantitative relationship between these parameters. This empirical parameterization was employed to calculate Rsn from PM2.5 with normalized mean bias (NMB) −0.09 and calculate PM2.5 concentration from Rsn with NMB −0.12. Our results indicate that this parameterization provides an efficient and straightforward method for estimating PM2.5 from Rs or Rs from PM2.5.

Ultraviolet (UV) radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization's measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes. The dataset consists of two compressed files, with the file names "observed uv radiation.zip" and "reconstructed uv radiation.zip". 1. The file "observed uv radiation.zip" contains the in situ-measured UV radiation dataset and comprises 40Excel worksheets. Each file contains the data collected at a single station. 2. The file "reconstructed uv radiation.zip" contains the reconstructed UV radiation dataset, which consists of 725 .txt files. The file named "station information.txt" contains information on the site locations, and the other 724 file names correspond to the station codes.

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The aim of this study was to reveal the long‐term variation properties of photosynthetically active radiation (PAR) over China. A series of reliable empirical PAR estimation equations suitable for all‐sky conditions were developed using data measured in situ from 2005 to 2014, which were obtained from the Chinese Ecosystem Research Network (CERN). These equations were then combined with a hybrid model to reconstruct the PAR from 1961 to 2014 for 724 weather stations belonging to the China Meteorological Administration (CMA). There was a decreasing linear trend in the PAR (with an amplitude of −0.009 mol m−2 day−1 year−1) from 1961 to 1981 and a steady low level of −0.003 mol m−2 day−1 year−1 during 1981–2014 for all of China. The PAR over the Tibetan Plateau (TP) region increased from 1961 to 1984; then, this linear trend slightly changed. The breakpoint years for the northwest China (NWC), southwest China (SWC), north China (NC), northeast China (NEC) and east China (EC) regions were 1985, 1981, 1996, 1998 and 1979, respectively. In addition, the aerosol optical depth, ozone column concentration, cloud cover and water vapour content attenuated the PAR that would otherwise have reached the earth’s surface by approximately 7.59, 1.12, 18.13 and 6.20%, respectively.