Important Influence of North Atlantic Oscillation on Interannual Variability of the Boreal Autumn East Siberian-Beaufort Sea Ice

The East Siberia-Beaufort Sea (EsCB) sea ice during boreal autumn has recently been reported to play important roles in the climate over Eurasia and North America. The EsCB sea ice exhibits remarkable year-to-year fluctuations in autumn (August-October), the season in which its minimum extent usually occurs. However, the physical driver of the autumn EsCB sea ice interannual variability remains unclear, impeding the seasonal prediction of local sea ice. Here we find that the autumn EsCB sea ice variability is largely driven by the preceding summer (May-July) dipolar atmospheric anomalies over the North Atlantic, resembling the North Atlantic Oscillation (NAO) pattern. During the negative NAO-like phase, the circumpolar anticyclonic anomalies tend to transport the warm air from Greenland toward the EsCB region, which triggers rapid sea ice melt there. The associated EsCB sea ice anomalies can be maintained or even intensi-fied by the local sea ice-albedo positive feedback until autumn. Therefore, the abnormal signals of Arctic sea ice tend to show significant persistence in summer and autumn. The influence of the summer NAO-like atmospheric circulation on the ensuing autumn EsCB sea ice can be realistically reproduced in the historical simulation of the E3SM-1-0 model, supporting our findings based on the observation. This lagged relationship provides a promising pathway for skillful seasonal prediction of the EsCB sea ice and its related climatic impacts.