Study of Distinctive Regional Features of Surface Solar Radiation in North and East China

Solar radiation is an important energy source for plants on the earth and also a major component of the global energy balance. Variations in solar radiation incident at the earth's surface profoundly affect the human and terrestrial environment, including the climate change. To provide useful information for predicting the future climate change in China, distinctive regional features in spatial and temporal variations of the surface solar radiation (SSR) and corresponding attributions (such as cloud and aerosol) are analyzed based on SSR observations and other meteorological measurements in North and East China from 1961 to 2007. Multiple models, such as the plane-parallel radiative transfer model, empirical and statistical models, and correlation and regression analysis methods are used in the study. The results are given as follows. (1) During 1961-2007, the total SSR in North China went through a process from quickly "dimming" to slowly "dimming", while in East China, a significant transition from "dimming" to "brightening" occurred. Although there are some differences between the two regional variation trends, long-term variations in SSR in the two regions are basically consistent with the observation worldwide. (2) Between the 1960s and 1980s, in both North and East China, aerosols played a critical role in the radiation dimming. However, after 1989, different variation trends of SSR occurred in North and East China, indicating that aerosols were not the dominant factor. (3) Cloud cover contributed less to the variation of SSR in North China, but was the major attribution in East China and played a promoting role in the reversal of SSR from dimming to brightening, especially in the "remarkable brightening" period, with its contribution as high as 70%.