Spring Barents Sea ice loss enhances tropical cyclone genesis over the eastern North Pacific

Arctic amplification caused by the rapid loss of Arctic sea ice has emerged as a crucial factor in affecting global weather and climate in recent decades. However, it remains unknown whether this rapid loss has exerted a specific impact on tropical cyclone (TC) activity over the eastern North Pacific (ENP). Here, we examine the influence of springtime (March-May) sea ice concentration (SIC) in the Barents Sea (SIC-BS), a key region for Arctic SIC changes, on TC genesis frequency over the ENP during the TC season (June-October) during 1970-2021. Results show that the reduced SIC-BS was favorable for more TC geneses over the ENP in terms of interannual variability. Further analyses based on dynamical diagnosis demonstrate that the rapid loss of SIC-BS leads to an upward transport of turbulent heat fluxes, facilitating the propagation of the Rossby wave train from the Barents Sea to the ENP via the western United States. This process subsequently leads to increase in upper-level divergence, mid-level upward motion, and lower-level vorticity, thereby accounting for the formation of more TCs over the ENP. This mechanism is further substantiated by the Coupled Model Intercomparison Project phase 6 (CMIP6). These results not only establish a possible connection between Arctic sea ice and tropical climate, but also hold important implications for understanding future changes in TC activity over the ENP.