Solar Brightening/Dimming over China's Mainland: Effects of Atmospheric Aerosols, Anthropogenic Emissions, and Meteorological Conditions

Surface solar radiation (SSR) is the main factor affecting the earth's climate and environment and its variations and the reason for these variations are an important part of climate change research. In this research, we investigated the long-term variations of SSR during 1984-2016 and the quantitative influences of atmospheric aerosols, anthropogenic emissions, and meteorological conditions on SSR over China's mainland. The results show the following: (1) The annual average SSR values had a decline trend at a rate of -0.371 Wm(-2) yr(-1) from 1984 to 2016 over China. (2) The aerosol optical depth (AOD) plays the main role in inducing variations in SSR over China, with r values of -0.75. Moreover, there are marked regional differences in the influence of anthropogenic emissions and meteorological conditions on SSR trends. (3) From a regional perspective, AOD is the main influencing factor on SSR in northeast China (NEC), Yunnan Plateau and surrounding regions (YPS), North China (NC), and Loess Plateau (LP), with r values of -0.65, -0.60, -0.89, and -0.50, respectively. However, the main driving factors for SSR in northwest China (NWC) are in cloud optical thickness of all clouds (TAUTOT) (-0.26) and black carbon (BC) anthropogenic emissions (-0.21). TAUTOT (-0.39) and total precipitable water vapor (TQV) (-0.29) are the main influencing factors of SSR in the middle-lower Yangtze Plain (MYP). The main factors that influence SSR in southern China (SC) are surface pressure (PS) (-0.66) and AOD (-0.43). This research provides insights in understanding the variations of SSR and its relationships with anthropogenic conditions and meteorological factors.

Automated summary

Surface solar radiation in China has shown a long-term declining trend, with main influencing factors including meteorological conditions and anthropogenic emissions. Different regions have varying influencing factors, with northeast China, Yunnan Plateau, North China, and Loess Plateau being mainly affected by aerosols, while northwest China is influenced by cloud optical thickness and black carbon emissions.