Statistically decreased weakening rate of typhoons in environments of the Northeast China cold vortex

The impact of the Northeast China Cold Vortex (NCCV) on tropical cyclone (TC) intensity change was studied based on statistics, revealing a significant decrease in the rate of TC weakening and a lower probability of rapid weakening (RW) in the environments of NCCVs. This is mainly attributable to the external dynamic forcing induced by the NCCV as the eddy angular momentum import at upper levels increases significantly, which offsets the unfavorable decrease in sea surface temperature and increase in vertical wind shear. The upper-level positive potential vorticity anomaly band from the NCCV involves into the TC circulation from the southwestern quadrant, helping the development of convections triggered in the downshear right side of the TC. These results elucidate a fundamental relationship between TCs and NCCVs, and the findings contribute to a deeper comprehension of TC behavior under the influence of NCCVs, thereby providing guidance for forecasting intensity changes of TCs entering mid-latitude regions.