Abstract:
This paper applied daily observed rainfall data in China, JRA-55 atmospheric reanalysis, ERSST monthly sea surface temperature (SST) data, Pacific decadal oscillation (PDO) and Ni?o3.4 index during 1981–2022, and revealed the dominant circulation regimes and large-scale SST anomalies of summer rainfall anomaly in Qinhuangdao and Tangshan (Qin-Tang region) on interannual time scale based on the EOF, correlation and composite analysis. Our results show the dominant mode of summer rainfall in Qin-Tang region exhibits a consistent variation on the interannual time scale with decreasing rainfall anomalies from north to south. The Mongolian cyclone (MC) and Sea of Japan high (SJH) are the dominant circulation, they both show significantly positive correlation with the summer rainfall anomaly in Qin-Tang region on the interannual time scale. The stronger MC and SJH are conducive to moisture transport, enhance the interaction of warm and cold air mess and extreme summer rainfall anomalies. When SJH is weak, the summer rainfall in this region is extremely less than normal due to the decrease of moisture transport. The negative (positive) phase of Ni?o3.4 index in winter and spring is usually followed by cold (warm) and warm (cold) SST in Indian and northwest Pacific Ocean in summer, which results in the stronger (weaker) SJH and more (less) rainfall in this region. While the positive phase of PDO in spring is often followed by warmer (colder) SST in north (south) of northwest Pacific Ocean in summer, which enhances the MC and the summer rainfall in this region, or vice versa. Therefore, the phase of PDO and Ni?o3.4 in winter to spring possibly provide a useful signal for the following summer rainfall forecast in this region. The results are applicable to the whole North China, which possibly benefits the seasonal forecast of summer rainfall in North China.