Different effects of eastern and central Pacific El Niño events on the surface shortwave radiation over southern China in winter

This study investigates the distinct impacts of eastern Pacific (EP) and central Pacific (CP) El Niño events on winter shortwave solar radiation (SSR) in southern China, revealing different spatial distributions and underlying mechanisms. The results show that, during the developing winter of EP El Niño, significant SSR reductions occur in southwestern China and the east coast of southern China due to a strong, zonally extended Northwest Pacific anticyclone that transports moisture from the tropical Northwest Pacific and North Indian Ocean, while the northeast of southern China experiences a weak increase in SSR. In contrast, during the developing winter of CP El Niño, SSR decreases in the east of southern China with a significant decrease in the lower basin of the Yangtze River but an increase in the west of southern China with a remarkable increase in eastern Yunnan. The pronounced east–west dipole pattern in SSR anomalies is driven by a meridionally elongated Northwest Pacific anticyclone, which enhances northward moisture transport to the east of southern China while leaving western areas drier. Further research reveals that distinct moisture anomalies during the developing winter of EP and CP events result in divergent SSR distributions across southern China, primarily through modulating the total cloud cover. These findings highlight the critical need to differentiate between El Niño types when predicting medium and long-term variability of radiation in southern China. 东部型(EP)和中部型(CP)厄尔尼诺发展年冬季中国南方地区地表太阳短波辐射(SSR)的空间分布特征存在明显差异.在EP厄尔尼诺发展年冬季, 受西北太平洋反气旋异常西伸的影响, 来自热带西北太平洋和北印度洋的水汽输送增强, 导致中国西南和华南沿海SSR明显减少, 中国南方东北部SSR微弱增加;在CP厄尔尼诺事件发展年冬季, 中国南方东部SSR减少(长江下游流域尤为显著), 而西部SSR增加(滇东地区增幅突出), 该偶极型异常分布与经向延伸的西北太平洋反气旋加强了中国南方东部的水汽北向输送有关.研究指出, 两类厄尔尼诺事件发展年冬季水汽异常存在明显差异, 并通过调控总云量导致中国南方SSR空间分布的差异.