Effects of precipitation, cloud cover, and aerosol on the surface shortwave radiation over northwest China

In this study, the relationship of the surface shortwave radiation (SSR) with the daily precipitation intensity (DPREI), total cloud cover (TCC), and aerosol optical depth (AOD) is analyzed for the five northwestern provinces (Xinjiang, Qinghai, Gansu, Ningxia, Shaanxi) of China. It reveals the influences of the different DPREI levels and different TCC and AOD levels on the SSR diurnal variation. The results show that the average SSR is stronger in Xinjiang and Qinghai, and the seasons with the stronger intensity of SSR and larger variation of diurnal SSR in the provinces of northwest China are summer and spring. Detailed analysis shows that the influence of DPREI, TCC, and AOD on SSR is greater in the eastern region of northwest China than that in the western region. In spring and summer, it is possible to select a factor among DPREI, TCC, and AOD which has the best-fitting relationship with SSR in each province of northwest China. When considering the DPREI, TCC, and AOD simultaneously, the fitting effect of SSR is better than that of the results fitted by the single factor. In particular, the fitting ability of SSR in Xinjiang and Qinghai has been significantly improved. According to the basic meteorological elements such as DPREI, TCC, and AOD, the variation characteristics of regional mean SSR under typical weather conditions can be obtained. It is helpful to assess the SSR simply just based on the weather information from the meteorological office.