Quantification of aerosol and cloud effects on solar energy over China using WRF-Chem

The promotion of renewable energy as a substitute for fossil fuels is the key solution to achieve the goals established during the United Nations Climate Change Conference in Glasgow (COP26) based on which member countries agreed to phase down coal power and achieve net-zero carbon emissions. Among various renewable energy sources, solar energy is an attractive option that will have a significant effect on the future energy supply and energy use. Therefore, we selected the period of 2016–2020 during which the aerosol concentration gradually decreased due to strict pollutant control measures to evaluate solar energy simulations based on the Weather Research Forecast-Chemistry (WRF-Chem) model. We also analyzed the contributions of the aerosol direct effect (ADE), aerosol indirect effect (AIE), and cloud radiation effect (CRE) to solar energy trends by conducting sensitivity experiments. The results show that the WRF-Chem model performs well for the 2 m temperature (T2), cloud fraction, PM2.5, solar energy trends during 2016–2020. There are regional and seasonal differences in the contributions of ADE, AIE, and CRE to solar energy trends, with a decrease in ADE contributions and an increase in CRE contributions from north to south in China, and the AIE contribution being relatively slight. On an annual scale, ADE is the main contributor to the increase in solar energy trends in the Beijing-Tianjin-Hebei (89%) and Fenwei Plains (83.9%) from 2016 to 2020, which is related to the horizontal distribution of PM2.5. In the Yangtze River Delta and other regions, ADE and CRE contributed equally to the increase in solar energy trends, about 40%. In the Pearl River Delta and Sichuan Basin, the contribution of CRE is larger than that of AIE and ADE, the Pearl River Delta region is the largest contributor of CRE to the annual solar energy trends among the five major urban agglomerations, with a contribution of 78.4%, and Sichuan basin is the only region where CRE has a negative contribution to the annual solar energy trends (−59.1%). On the seasonal scale, the contribution of CRE is dominant except for the greater positive contribution of ADE to the solar energy trends in spring, summer, and autumn in Beijing-Tianjin-Hebei and in autumn in Fenwei Plain.