Variability of surface solar radiation under clear skies over Qinghai-Tibet Plateau: Role of aerosols and water vapor

Abstract

Surface solar radiation (SSR) plays a vital role in the global energy cycle and the interaction between the earth and atmosphere. It has a significant impact on climate change. Aerosols and water vapor are important factors affecting the variations in clear-sky SSR. This study analyzed the effects of aerosols and water vapor on clear-sky SSR in the Qinghai-Tibet Plateau (QTP), one of the most sensitive areas to global climate change, over the past 20 years. The results show that the 87.0% of the monthly clear-sky SSR over QTP can be explained by the monthly aerosols and water vapor. The aerosol direct radiative effect (ADRE) value in most QTP areas (93.35%) is lower than −10 W m−2. The effect of water vapor on the monthly value of clear-sky SSR is greater than that of aerosols. The reduced clear-sky SSR (about 61.36% of QTP areas) in the past 20 years is mainly concentrated at the south–north boundary. The significant increases in sulfate and carbonaceous aerosols from India have contributed to the decrease in clear-sky SSR in the South. Moreover, the increasing water vapor influx from the southern boundary is also an important reason for the reduction in clear-sky SSR in the South and North. The results also indicate that the decrease in dust aerosols, originating from the Taklamakan and Qaidam Deserts, results in the increase in clear-sky SSR in the Northeast.