Comparative Climatology of Northeastern China Cold Vortices With and Without Accompanying Extratropical Cyclones

This study classifies northeastern China cold vortices (NCCVs) into two types—those accompanied by extratropical cyclones (ECs) and those without—and compares their climatological characteristics and evolutionary dynamics. Using 6-hourly NCEP_FNL reanalysis data (2000–2023, 1.0° × 1.0°), NCCVs were identified from 500-hPa geopotential height and ECs from sea level pressure. An NCCV was considered EC-accompanied if the distance between their centers was <500 km or, under strong baroclinicity, < 1500 km with a relative radius ratio < 0.6. Results show that EC-accompanied NCCVs occur most frequently in May–June and November, exhibiting an east–west seasonal oscillation tied to the position and strength of the upper-level jet stream. Compared to non-EC NCCVs, they are significantly more intense (16.4 vs. 11.9 dagpm), larger (672 vs. 541 km radius), and longer-lived (4.2 vs. 4.0 days), with a deeper vertical structure and a more organized life cycle characterized by westward tilt with height during intensification and a barotropic structure during decay. Critically, in 93.5% of the cases, the initial NCCV–EC co-occurrence precedes the NCCV intensity peak; the lead time ( \Delta duration) is positively correlated with peak intensity and system radius, suggesting that early EC coupling favors enhanced baroclinic energy release and subsequent NCCV growth. These findings clarify the two-way interaction between NCCVs and ECs and provide a potential predictor for NCCV intensity evolution in operational forecasting.