An Autumn Arctic Pacific Sea-ice Dipole as a Source of Predictability for Subsequent Spring Barents-Kara Sea-ice Condition

This study uses observational and reanalysis datasets in 1979-2016 to show a close connection between an autumn sea-ice dipole in the Arctic Pacific sector and sea-ice anomalies in the Barents-Kara Seas (BKS) during the following spring. The September-October Arctic Pacific sea-ice dipole variations are highly correlated with the subsequent April-May BKS sea-ice variations (r=0.75), uncovering a new source of predictability for spring BKS sea-ice forecast at 7-month lead time. The sea-ice dipole, manifested as sea-ice retreat in the Beaufort-Chukchi Seas and expansion in the East Siberian-Laptev Seas, is first produced by preceding shortwave radiation in summer and later relates to a positive polar cap anomaly during autumn and winter with its center slowly moving toward Greenland. The migration of the anomalous stratospheric circulation is followed by a negative North Atlantic Oscillation-like anomaly in the troposphere in mid-winter, leading to reduced heat transport into the BKS region where sea-ice extent increases.