Summertime atmosphere–ocean preconditionings for the Bering Sea ice retreat and the following severe winters in North America

Atmospheric responses to sea ice retreat in the Bering Sea have been linked to recent extremewinters inNorthAmerica.We investigate the leading factor for the interannual variability of Bering sea ice area (SIA) in early winter (November–December), using canonical correlation analysis based on seasonally resolved atmosphere and ocean data for 1980–2014.We found that the 3-month leading (August–September) geopotential height at 500 hPa (Z500) in theNorthernHemisphere explains 29%of SIA variability. The spatial pattern of Z500 for positive (negative) sea ice anomalies is associated with negative (positive) anomalies over theGulf of Alaska related to the Pacific transition (PT) pattern. The heat budget analysis indicates that summertime atmospheric conditions influence SIA through the ocean temperature anomalies of theAlaskanCoastal Current forced by atmospheric turbulent heatfluxes. The PTpattern highly correlates with convective precipitation in thewestern subtropical Pacific, implying that weakened subtropical forcing is the likely cause for the recent extremewinters in NorthAmerica. Our results present amajor factor for interannual variability in the Bering SIA, and furtherwould contribute to the improvement of forecasting winter climate inNorthAmerica.