Variation of Surface Solar Radiation over the Central and East of Southern China

Surface solar radiation is one of most essential variables that influence the climate and environment. Various studies analyzing long-term records of surface radiation measurements suggest a widespread decrease in surface solar radiation between the 1950s and 1980s (global dimming), with a partial recovery more recently at many locations (brightening). To provide reasonable evidence for predicting the future trend of climate changes, the spatial and temporal variation of surface solar radiation and the causes are analyzed comprehensively by using observational solar radiation data together with conventional meteorological data of the central and east of southern China from 1961 to 2007.Solar radiation is obviously declining during 1961—1990 over the central and east of southern China, and a widespread brightening is observed during 1989—1995, but from 1995 to 2007 brightening doesn't persist and the solar radiation tendency tends to moderation. Increase of aerosol may be the main causes of solar radiation from dimming to brightening during 1961—1990, and the difference of cloud cover tendency maybe the main causes of solar radiation dimming.Model simulation shows that in recent 50 years water vapor is rising, which has decreased solar radiation by 0.55 W·m^-2 at the beginning of the 21st Century than that of the 1980s, but it is not main cause of solar radiation from dimming to bighting in recent 50 years. A widespread ascending aerosol optical depth (8.8%) is observed from 1980 to 2007, but the tendency tends to moderation. Due to the joint effect of atmosphere moisture and aerosol optical depth, a variation of aerosol direct radiative forcing is weakened, and the overall trend shows that aerosol direct radiative forcing variation trend to moderation (0.22 W·m^-2 in the country and 0.29 W·m^-2 in the city).Entering the 21st Century, solar radiation tends to moderation. This tendency indicates the cause for solar radiation change of China in the 1990s is different from Europe and America, and aerosol decline is not the major contributor. On the other hand, it also demonstrates if the air quality improves in the future, the solar radiation over the central and east of southern China may rise again.