Contributions of Driving Factors to Variations in Global Surface Solar Radiation

Observations have recorded significant decadal changes in the global surface solar radiation (SSR) over the past, a phenomenon known as the ‘global dimming’ and ‘brightening’. Many studies suggest that changes of SSR are dominated by aerosols, clouds, and other influences at the atmosphere. However, due to the lack of suitable data and methodology, there are few global evaluations and quantitative work that reveal the relative importance of impacting factors on the SSR trends. In this study, a linear regression method is used to investigate the driving factors of global SSR and to quantify their contributions to the long-term change and distribution of SSR. Based on a reanalysis dataset, from 2000 to 2023, the distributions and trends of SSR can be well explained by the linear regression model, with crucial variables such as aerosol optical depth (AOD), cloud radiative effect and water vapor as predictors. The model performs particularly well at low and middle latitudes. We find that under all sky condition, cloud radiative effect causes approximately 70% of the variation in SSR, which has the strongest influence on SSR among the other predictors. In addition, all-sky SSR also shows very high sensitivity to water vapor and AOD.