On the drivers of variability and trend of surface solar radiation in Great Beijing area of China

On the drivers of variability and trend of surface solar radiation in Great Beijing area of China

Xiaoling Zhang, Institute of Urban Meteorology, Chinese Meteorology Administration, Beijing, 100089 Xiangao Xia, LAGEO, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China, 100029

Chunyi Xuan, Beijing Municipal Climate Center, Beijing, China, 100089

Abstract: The objective of this study is to further our understanding of variability and trend of surface solar radiation (SSR) in the Great Beijing area of China, and cloud cover and aerosol optical depth (AOD) are compared. This is achieved by a detailed analysis of surface meteorological observation data during 1961-2007 at 20 meteorological sites in this area. As expected, cloud cover is an important factor determining the inter-annual variation of SSR. However, the decadal and long-term trend of SSR can not be attributable to cloud cover. AOD plays an important role in the variability of SSR, more importantly, AOD was observed to increase during this period and this is the major driver of the dimming observed in the Great Beijing area. A high negative correlation between cloud cover and SSR was found, however, long-term behavior of cloud cover and SSR were generally positive correlated, which suggested significant decreasing of SSR could not be attributable to cloud cover changes. There is strong evidence from data analysis that aerosol optical depth is the major driver of variability and trend of SSR, which is supported by the fact that both high frequency and low frequency of SSR are negatively correlated to that of AOD. An increase in AOD during this period is in good accordance with the observed decrease in SSR.

Correspondence to: Zhang Xiaoling (xlzhang@ium.cn)