New Variation Characteristics of the Northeast China Cold Vortex Precipitation and Their Atmospheric Circulations and Sea Surface Temperature Backgrounds

In this study, based on the daily precipitation observations in Northeast China (NEC) , the monthly mean atmospheric circulation reanalysis data obtained from the National Centers for Environmental Prediction/National Center for Atmospheric Research, and the reconstructed monthly mean sea surface temperature (SST) data from the National Oceanic and Atmospheric Administration, we analyze the spatio-temporal evolution characteristics of Northeast China Cold Vortex (NCCV) precipitation and its percentage to the total precipitation from 1961 to 2023. Additionally, the abrupt change in the interdecadal NCCV precipitation is investigated, and the possible causes of the interdecadal shifts in the seasonal NCCV precipitation are examined from the perspectives of concurrent atmospheric circulations and preceding SST (pre-SST). The results reveal distinct interannual variations in the NCCV precipitation during 1961–2023. Except autumn NCCV precipitation, which displays a decreasing trend, spring, summer and winter NCCV precipitation show increasing trends, among which the increasing trends in spring and summer are statistically significant. The NCCV precipitation percentages increase significantly in spring and summer but decrease in autumn and winter. During 1961–2023, the spring NCCV precipitation exhibit an interdecadal shift from less to more, linked to the noticeable strengthening of the influence from the NCCV. Corresponding to the combined pattern of the blocking high and the NCCV, the cyclonic circulation over the NEC becomes more pronounced. Meanwhile, the positive correlation of the pre-SST key area in the Pacific expands, and the North Atlantic tripolar pattern disappears. Summer NCCV precipitation shows an interdecadal shift from less to more, with a strengthened NCCV influence. After the shift, the western Pacific subtropical high (WPSH) and the blocking high cooperate more closely with the NCCV, the NCCV intensifies, and the significant correlation of the pre-SST key area in the Indian and Pacific Oceans expands, while the North Atlantic exhibits a tripolar “positive-negative-positive” pattern. In contrast, autumn NCCV precipitation displays an interdecadal shift from more to less, with weakened influences of both the WPSH and NCCV. In addition, the circulation over the NEC shifts from cyclonic flows to easterlies, and the correlation of the pre-SST key area in the Pacific shows a “positive-negative- positive” correlation from low to high latitudes. In terms of winter NCCV precipitation, no significant change in circulation patterns over the NEC is observed before and after the interdecadal abrupt shift. However, there is an expansion in the significant correlation of the pre-SST key area in the Pacific, while the influence of the North Atlantic tripole weakens after the abrupt shift.