Analysis of the Causes and Mechanism of Abnormal Circulation During Heavy Precipitation Events in the Starting Section of the Arctic Northeast Passage

The rapid melting of Arctic sea ice has significantly lengthened the window for Northeast Passage navigation, but the frequent occurrence of accompanying extreme weather events poses severe challenges to shipping safety. Based on 1991–2020 climate data and 2021–2024 NCEP reanalysis data, this study uses wave activity flux diagnosis, composite analysis and statistical test methods to reveal the causes of abnormal circulation and the energy propagation mechanism of heavy precipitation events during the navigation period (July–October) in the starting section of the Arctic Northeast Passage (from the Barents to the Kara Sea). The results show that from 2021 to 2024, there was a high proportion of heavy precipitation events during the navigation period (July–October), with significant temporal and spatial variability; abnormal circulation is triggered by the synergistic effect of the eastward shift in the Ural blocking high and the southward extension of the Arctic polar vortex. The enhanced upper-level westerly jet and the mid-level “tripole-type” teleconnection wave drive jointly drive the northward transport of warm, moist air, and the low-level cyclonic circulation and upper-level divergence trigger a baroclinic lifting mechanism. Rossby wave energy originates from the Mediterranean–Black Sea region, propagating eastward to the study area along the jet axis and enhancing the ascending motion through wave activity flux divergence. The heavy precipitation event in August 2023 is a typical example of the cross-seasonal synergistic sea temperature–sea ice–atmosphere effect. This study reveals the following complete teleconnection chain: “sea temperature anomaly → wave train excitation → sea ice feedback → circulation maintenance”, which will support predicting disastrous weather and developing climate adaptation strategies in the Arctic Passage.