Contribution of the Northeast China Cold Vortex to the Persistent Extreme Precipitation Events over the Yangtze–Huaihe River Basin

Abstract Persistent extreme precipitation events (PEPEs) have dramatic socioeconomic impacts in the Yangtze–Huaihe River basin (YHRB). However, the possible role of the Northeast China cold vortex (NEC-CV) in modulating the PEPEs over the YHRB remains unresolved. In this study, the contribution of NEC-CVs to summer precipitation is first examined over central-eastern China, which is characterized by a local and long-distance effect, along with distinct geographic variability. Limited influence is found for the areas outside a threshold of 4× radius of NEC-CV. The YHRB is one of the regions significantly affected by the NEC-CVs, which accounts for about 35%–40% of the total extreme precipitation. During 1961–2022, about 27.7% of the total PEPEs are found to be closely related to the NEC-CVs. In addition, two types of PEPEs (type W/type E) are identified based on the position of corresponding NEC-CV tracks. Significant impacts are found for the opportune configurations of NEC-CVs. The PEPEs are found to be located more westward/eastward for type W/type E, with the anomalous moisture mainly coming from the western North Pacific/South China Sea. The two PEPEs exhibit the anomalous eastward/westward extension of the South Asian high/western North Pacific subtropical high and anomalous southward shift of the upper-level jet with respect to the climatology. Meanwhile, the lower troposphere is dominated by a large-scale low pressure, strong wind shear, and intense moisture transport in the YHRB. The concurrent combinations of the upstream Ural blocking and the downstream Okhotsk blocking are favorable for the development and southward intrusion of NEC-CVs to the YHRB in type W. However, the counterparts in type E are closely associated with the upstream Baikal blocking. The precursor signals of the NEC-CVs can be detected 12/8 days prior to the peak PEPE occurrence at 500 hPa for type W/type E. Significance Statement Persistent extreme precipitation events (PEPEs) can cause catastrophic flooding. This study demonstrates the role of the Northeast China cold vortex (NEC-CV) in influencing such high-impact weather events in the Yangtze–Huaihe River basin (YHRB). Using the latest reanalysis datasets and neural network technology, we quantitatively conclude that the NEC-CVs have contributed to about 35%–40% of the total extreme precipitation and 27.7% of the total PEPEs in the YHRB over the past 60 years. The relevant PEPEs are dominated by the NEC-CVs, with the opportune configuration of the upper and lower circulation systems. These key findings present a new perspective on the meteorology of the PEPEs with implications for the medium-range weather forecasts.