Effects of single-layer low clouds on the surface solar radiation in East Asia

Abstract

The earth surface solar radiation is largely influenced by the physical properties of low clouds, which need to be investigated for effectively utilizing the solar energy. In this paper, four different regions in East Asia were selected and NASA CERES (Clouds and the Earth's Radiant Energy System) SSF (Single Satellite Footprint) Aqua Edition 3A data from the year 2003 to 2016 were used to analyze the annual and inter-annual variations in the low cloud coverage, ice water path and liquid water path of the single-layer low clouds. Results showed that these three physical property parameters achieved their maximums in December or January for most regions. For the past 14 years, both the low cloud coverage and liquid water path achieved their highest multi-year averages and largest fluctuation ranges in the southern region, while the ice water path achieved its highest multi-year average and largest fluctuation range in the northwestern region. The cooling effect of single-layer low clouds on the solar radiation depended on the regions and seasons. For the past 14 years, the cooling effect of single-layer low clouds showed an overall weakening tendency in the northwestern region, but an overall strengthening tendency in the other three regions, and especially, in the southern region. Regarding the correlation to the surface shortwave radiation, the liquid water path was a closer factor for most regions, while the ice water path was an insignificant factor, especially in the northwestern region.