资源环境科技发展态势分析平台

Increasing energy and food demands require an understanding of not only the availability and variability of total solar radiation (R) but also its partitioning into direct (R-d) and diffuse (R-f) components, which are key elements for solar power generation and plant photosynthesis, respectively. Potential inhomogeneities in surface solar radiation observations, however, add uncertainties to the published patterns and trends of R-d and R-f over China. To exclude inhomogeneous time series and outliers, a data quality control process has been applied to the surface observations of R-d and R-f. The homogeneous data show that, in response to the global dimming and brightening phenomena in R, decadal changes can also be observed in the R-d and R-f trends over China with the actual transition occurring in the mid-2000s. Since the 1960s, R-d dimming has mainly distributed over eastern China with intensive anthropogenic activities, with recoveries especially from 2008 onward over regions with high R-d energy potential. R-f, on the other hand, had further enhanced since the 1960s especially over the high R-f proportion areas but has decreased in the recent decade over the northern region. The summer season shows the most significant decadal trends in R-d and R-f. Under clear-sky conditions, that is, ruling out cloud effects, the transitions in R-d and R-f trends become more remarkable, pointing to atmospheric aerosols as the main driving force. In addition, dramatic R-d and R-f variations are observed in the subsequent years after large volcanic eruptions. The varying R-d and R-f proportions are in line with recent governmental control on SO2 emissions over China.