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

Using daily precipitation records from Northeast China (NEC), monthly mean atmospheric circulation reanalysis data from the National Centers for Environmental Prediction/National Center for Atmospheric Research, and reconstructed monthly mean sea surface temperature (SST) data from the National Oceanic and Atmospheric Administration, this study examined the spatiotemporal evolution of Northeast China cold vortex (NCCV) precipitation and its proportion of total precipitation during 1961–2023. Abrupt interdecadal changes in NCCV precipitation are identified, and potential drivers of seasonal shifts are analyzed in relation to concurrent atmospheric circulation and preceding SST (pre-SST). Results indicate pronounced interannual variability in NCCV precipitation. Spring, summer, and winter NCCV precipitation showed increasing trends, with significant rises in spring and summer, while autumn exhibits a declining trend. The proportion of NCCV precipitation increases significantly in spring and summer, but decreases in autumn and winter. Spring NCCV precipitation exhibited an interdecadal shift from lower to higher values, accompanied by strengthened NCCV activity, enhanced coordination between the blocking high and NCCV, and a vanished North Atlantic tripolar pattern. Summer NCCV precipitation exhibited an interdecadal increase. After this shift, closer interaction between the western Pacific subtropical (WPSH), blocking high, and NCCV is observed, with expanded correlations in the Indian and Pacific pre-SST regions, while the North Atlantic exhibits a tripolar "positive-negative-positive" pattern. In contrast, autumn NCCV precipitation displayed an interdecadal shift, with weakened WPSH and NCCV influences, with circulation over NEC transitioning from cyclonic to easterlies, and Pacific pre-SST correlation displaying a "positive-negative-positive" latitudinal pattern. Winter NCCV precipitation revealed no significant circulation changes over NEC before or after the abrupt interdecadal shift, despite significant Pacific pre-SST correlations expansion and North Atlantic tripole influence decline.