Association Analysis on the Seasonal Surface Solar Radiation Anomaly in China and Major Atmospheric Circulation Indices

The association between the seasonal major atmospheric circulation indices and the surface solar radiation anomaly (SSRA) in China is investigated using ERA5 SSR downwards data from 1989 to 2018. The results show that (1) in spring, the location of the East Asian trough has a consistent influence on the SSRA in the large areas of central-eastern China, and the SSRA is significantly less when the location of the East Asian trough is eastward. The intensity of the East Asian winter monsoon affects the SSRA inversely in the southern and northern Yangtze river basins, whereas El Niño–Southern Oscillation (ENSO) affects the SSRA inversely in the eastern and western parts of south China. (2) In summer, the influencing factors are complicated. The North Atlantic Oscillation (NAO) and summer monsoon are important. The NAO has a significant influence on the SSRA in many parts of north China, and the summer monsoon is associated with the SSRA in the Yangtze–Huaihe River basin. When the NAO index is higher (lower), the SSRA in large parts of north China is less (more). When the summer monsoon index is higher (lower), the SSRA in the Yangtze–Huaihe River basin is significantly less (more). (3) In autumn, the SSRA is connected with the location of the East Asian trough, winter monsoon, and NAO. The SSRA in north China is primarily influenced by the winter monsoon and the location of the East Asian trough. The SSRA in large parts of north China except for Northeast China appears more when accompanied by the western East Asian trough or strong winter monsoon. Moreover, when associated with the SSRA in western China, the higher NAO index can lead to less SSRA in the northern part of western China and more SSRA in the large southern parts of western China. (4) In addition, ENSO and winter monsoon are two important factors affecting the SSRA in winter, but their significant influencing areas are asymmetric. Negative ENSO phases or intense winter monsoon can cause more SSRA significantly in most parts of northern China, and positive ENSO phases or weak winter monsoon are most favorable to the less SSRA in southern China, but on a small significant scale.