Towards an Operational Seasonal Sea Ice Forecast System for the Chukchi Sea

Abstract:

We utilize statistically-modeled ocean heat and volume transports through the Bering Strait along with additional predictors to create skillful predictions of sea ice retreat and advance dates in the Chukchi Sea, a key region for shipping and other growing economic activities in the Arctic. Inter-annual variability of June and September oceanic volume transports through the strait can be captured using along-strait surface winds and modeled Ekman transports in the Bering and East Siberian Seas. Combining the modeled volume transports with sea surface temperatures in the Bering Sea in turn enables skillful representations of June and September ocean heat transport (OHT) variability. These modeled OHTs, along with the linear trend in retreat and advance dates, explain 65% and 74% of retreat and advance date variance in the Chukchi Sea at one-month leads. Addition of the retreat date anomaly into the advance date model improves the explained variance of the model to 82%. Using only variables initialized July or earlier, we can explain 75% of the ice advance date variance. Forecast skill can be further increased by improving parameterizations of Bering Strait water temperatures, especially in spring and early summer. These findings are significant in offering a path towards operational forecasts of sea ice retreat and advance dates in the Chukchi Sea in the absence of direct observations of OHT from moorings in the Bering Strait.