A comprehensive research on the global all-sky surface solar radiation and its driving factors during 1980–2019

Abstract

The study evaluated monthly surface solar radiation (SSR) by the second Modern-Era Retrospective Analysis for Research and Applications (MERRA-2) reanalysis and investigated the long-term trend of SSR in regions with excellent performance of reanalysis worldwide. Overall, MERRA-2 performed well in North America (NA), Europe (EUR), Northern East Asia (NEA) and Oceania (OCE). The results suggest that from 1980 to 2019, there has been a widespread downtrend of SSR in NA, NEA and OCE, at −0.316, −0.001 and − 1.140 W m−2 decade−1, respectively, an uptrend at 0.633 W m−2 decade−1 of EUR. NA showed the strongest brightness by 5.886 W m−2 decade−1 in 1982–1991. This was associated with the decrease of low cloud fraction (−0.024 decade−1), resulting in the weakening (3.164 W m−2 decade−1) of the attenuation effect of cloud on radiation. In EUR, SSR was also affected by cloud changes. The attenuation effect of clouds on SSR was weakened in 1981–1990 and enhanced in 1989–1998, which led to the strongest brightening (4.556 W m−2 decade−1) and dimming (−1.587 W m−2 decade−1), respectively. And in NEA, the reduction of clouds and aerosols dominated the strong brightening by 4.721 W m−2 decade−1 during 1992–2001. In addition, NEA experienced the strongest dimming during 1997–2006, which was mainly related to the increase of aerosols. Finally, in OCE, SSR was primarily affected by the water vapor and cloud together, and the strongest brightening (10.130 W m−2 decade−1) and the strongest dimming (−8.892 W m−2 decade−1) occurred in 2010–2019 and 2001–2011, respectively.