Tropical cyclone activity over western North Pacific favors Arctic sea ice increase

Teleconnections between the tropics and the Arctic are of great interest, yet the mechanisms by which tropical synoptic-scale systems influence Arctic sea ice variability remain unclear. This study highlights the impact of tropical cyclone (TC) activity over the western North Pacific (WNP) on Arctic Sea Ice Concentration (SIC) using observations and climate model experiments. Significant positive correlations are found between Accumulated Cyclone Energy (ACE) in the WNP and SIC in the Arctic-Pacific Sector (APS), especially with a 30‑day lag. WNP TC activity induces Rossby wave trains that propagate poleward, establishing anomalous cyclonic circulation over the upper troposphere of the APS. This deepens the Arctic polar vortex and reduces adiabatic warming, cooling and drying the lower Arctic air, decreasing downward longwave radiation, and promoting an increase in September APS SIC. The anomalous cyclone also hinders sea ice export and melting through the Fram Strait. These results advance understanding of tropics–Arctic teleconnections.