Abstract:
This study used daily observed rainfall data in China, atmospheric reanalysis, monthly sea surface temperature (SST) data, Pacific decadal oscillation (PDO) and Niño3.4 index during 1981–2022, revealed the interannual variability of summer rainfall anomaly in Qinhuangdao and Tangshan (Qin–Tang region) and the large-scale circulation regimes and SST anomalies influence on it based on the Empirical Orthogonal Function and correlation and composite analyses. Our results show that the dominant mode of summer rainfall in the Qin–Tang region exhibits consistent variation on the interannual time scale, with rainfall anomalies decreasing from north to south. The Mongolian cyclone (MC) and the Sea of Japan High (SJH) are dominant circulations, both showing a significant positive correlation with the summer rainfall anomaly in the Qin–Tang region on the interannual time scale. Stronger MC and SJH are conducive to moisture transport, enhance the interaction of warm and cold air mess, and cause extreme summer rainfall anomalies. When SJH is weak, summer rainfall in this region is extremely lower than normal due to a decrease in moisture transport. The negative (positive) phase of the Niño3.4 index observed in winter and spring is usually followed by cold (warm) and warm (cold) SST in the Indian and northwest Pacific Ocean in summer, respectively, which results in stronger (weaker) SJH and more (less) rainfall in this region. The positive phase of PDO noticed in spring is often followed by warmer (colder) SST in the north (south) of the northwest Pacific Ocean in summer, which increases MC and summer rainfall in this region or vice versa. Therefore, the phases of the PDO and Niño3.4 index observed from winter to spring possibly provide a useful signal for the accurate seasonal prediction of following summer rainfall in this region. These results are applicable to the whole of North China, which possibly benefit for the spatially accurate seasonal forecasting of summer rainfall.