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

This study classifies Northeast China cold vortices (NCCVs) into two types—those accompanied by extratropical cyclones (ECs) and those without—and compares their climatological characteristics and evolutionary dynamics. On the basis of 6-hourly, 1.0° × 1.0° NCEP Final (FNL) Operational Global Analysis data for 2000–2023, NCCVs and ECs were identified using the 500-hPa geopotential height and sea-level pressure fields, respectively. An NCCV was classified as EC-accompanied if either (a) the distance between the NCCV center and the EC center was less than 500 km, or (b) under strong baroclinicity, this distance was less than 1500 km and the relative radius ratio was below 0.6. The 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-accompanied 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 cases, the initial NCCV–EC co-occurrence precedes the NCCV intensity peak; the lead time 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 potential guidance for NCCV intensity evolution in operational forecasting.