Prolonged Lifetime and Atypical Westward Propagation of Mesoscale Convective Systems in the Cold-Core Vicinity of the Northeast China Cold Vortex 

The Northeast China Cold Vortex (NCCV), especially the uniform cold environment near the NCCV core, is a favorable background for initiation of mesoscale convective systems (MCSs), but prior research lacks analysis of the attributes of such MCSs. Based on Himawari-8 satellite infrared brightness temperature and NCCV positioning data, this study investigated and compared the characteristics of ordinary MCSs (Ord-MCSs) and MCSs accompanied by the NCCV (CV-MCSs) over Northeast China and its vicinity during April–September of 2018–2022. By using an improved label-inheritance method, a total of 1707 Ord-MCSs and 229 CV-MCSs were identified, with the occurrence of both types of MCSs peaking from June to August. Key findings reveal that, compared with Ord-MCSs, CV-MCSs exhibit a notably extended lifecycle duration, broader convective shield and precipitation areas, but a similar maximum convective core area. Moreover, CV-MCSs form in environments with lower convective available potential energy, lower 500-hPa temperature, and higher relative humidity throughout the mid–lower troposphere. Consequently, CV-MCSs have a smaller lifetime maximum convective core area but a larger lifetime maximum convective shield area and greater lifetime maximum precipitation coverage, together with notably longer life duration. Additionally, CV-MCSs show stronger tendency to move westward, follow longer trajectories and attain higher average speeds than Ord-MCSs moving in the same direction. These results highlight that the cold, humid, and stable environment near the NCCV core favors the development of extensive, long-lived, but not necessarily most intensely convective MCSs, offering new insights for refining regional forecasts of convective system evolution under cold vortex conditions.