The Quadrupole Precipitation Pattern over Eastern China and Its Associated Atmospheric Circulations and Ocean Conditions

The diversity of summer precipitation regimes over eastern China has raised concerns. Its variations during different warming periods and the relevant mechanisms remain unclear. In this study, the decadal precipitation changes and the associated atmospheric circulations, ocean conditions, and warming over Northern Hemisphere were investigated. The results indicated a quadrupole precipitation pattern over eastern China in the boreal summer, with a significant shift around 1998. From 1985-98 to 1999-2014, two wet anomalies were over North China (NC) and South China (SC), while two dry anomalies were over the Yangtze-Huaihe River basin (YHRB) and northeastern China (NEC). This quadrupole pattern is associated with the circumglobal teleconnection (CGT), the negative phase of the interdecadal Pacific oscillation ("2IPO"), the warming over the high latitudes of North Atlantic ("1HNA"), and the warming rate over the Northern Hemisphere (NWR). The CGT would induce the weakened polar front jet (PJ), southward shift of the PJ, and northward shift of the entire subtropical jet (SJ), which decreased the meridional distance between the PJ and SJ, and therefore resulted in the NC-wet-YHRB-dry-SC-wet variation. As well, the dry NEC was attributed to the enhanced PJ, weakened Iranian Plateau subtropical jet (IPSJ), and northward movement of the PJ and Tibetan Plateau subtropical jet (TPSJ), which were accompanied by 2IPO and 1HNA. Moreover, the NWR led to the weakened PJ and SJ, as well as the southward shift of PJ, also contributed to the dry YHRB, and wet anomalies over NC and SC. Particularly, the 1HNA plays an important role in this quadrupole precipitation variation. Our findings have highlighted the role of jet streams in complex precipitation patterns, which will contribute to understanding the diverse variations in precipitation regimes over eastern China under global warming.