A climatological analysis of northward-moving typhoon in environments of the Northeast China cold vortex

This study investigates the influence of the Northeast China cold vortex (NCCV) on the northward-moving typhoons (NTCs) over the western North Pacific (WNP). There is a significant inverse relationship between the NCCV during June–September and simultaneous NTCs during 1981–2021. Fewer (more) NTCs are observed during NCCV active (inactive) year a combination of less (more) NTC genesis, particularly over the central Pacific region of 10°–30° N and 130°–150° E, and fewer (more) NTCs moving northwestward and making landfall in coastal regions of the Yellow Sea and Bohai Sea. These regions are characterized by significantly decreased low-level vorticity and mid-level humidity, which impedes NTC genesis and notably enhances the deep-layer subtropical straight westerly steering flow, thus blocking the northward movement of NTCs. These remarkable environmental changes during different NCCV years are clearly linked with the changes of an anomalous anticyclone in the subtropics (20°–30° N, 120°–160° E). In short, more (less) NCCV activity strengthens (weakens) the anomalous anticyclone, resulting in fewer (more) NTCs.