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Abstract Predictability of seasonal sea ice advance in the Chukchi Sea has been investigated in the context of ocean heat transport from the Bering Strait; however, the underlying physical processes have yet to be fully clarified. Using the Pan-Arctic Ice–Ocean Modeling and Assimilation System (PIOMAS) reanalysis product (1979–2016), we examined seasonal predictability of sea ice advance in early winter (November–December) and its source using canonical correlation analysis. It was found that 2-month leading (September–October) surface heat flux and ocean heat advection is the major predictor for interannual variability of sea ice advance. Surface heat flux is related to the atmospheric cooling process, which has influenced sea ice area in the southeastern Chukchi Sea particularly in the 1980s and 1990s. Anomalous surface heat flux is induced by strong northeasterly winds related to the east Pacific/North Pacific teleconnection pattern. Ocean heat advection, which is related to fluctuation of volume transport in the Bering Strait, leads to decrease in the sea ice area in the northwestern Chukchi Sea. Diagnostic analysis revealed that interannual variability of the Bering Strait volume transport is governed by arrested topographic waves (ATWs) forced by southeasterly wind stress along the shelf of the East Siberian Sea. The contribution of ocean heat flux to sea ice advance has increased since the 2000s; therefore, it is suggested that the major factor influencing interannual variability of sea ice advance in early winter has shifted from atmospheric cooling to ocean heat advection processes. Significance Statement Predictability of sea ice advance in the marginal Arctic seas in early winter is a crucial issue regarding future projections of the midlatitude winter climate and marine ecosystem. This study examined seasonal predictability of sea ice advance in the Chukchi Sea in early winter using a statistical technique and historical model simulation data. We identified that atmospheric cooling and ocean heat transport are the two main predictors of sea ice advance, and that the impact of the latter has become amplified since the 2000s. Our new finding suggests that the precise information on wind-driven ocean currents and temperatures is crucial for the skillful prediction of interannual variability of sea ice advance under present and future climatic regimes. 

Seasonal, interannual, and decadal variations in the Arctic ice‐algal productivity for 1980–2009 are investigated using daily outputs from five sea ice‐ocean ecosystem models participating in the Forum for Arctic Modeling and Observational Synthesis project. The models show a shelf‐basin contrast in the spatial distribution of ice‐algal productivity (ice‐PP). The simulated ice‐PP substantially varies among the four subregions (Chukchi Sea, Canada Basin, Eurasian Basin, and Barents Sea) and among the five models, respectively. The simulated annual total ice‐PP has no common decadal trend at least for 1980–2009 among the five models in any of the four subregions, although the simulated snow depth and sea‐ice thickness in spring are mostly declining. The model intercomparison indicates that an appropriate balance of stable ice‐algal habitat (i.e., sea‐ice cover) and enough light availability is necessary to retain the ice‐PP. The multi‐model averages show that the ice‐algal bloom timing shifts to an earlier date and that the bloom duration shortens in the four subregions. However, both the positive and negative decadal trends in the timing and duration are simulated. This difference in trends are attributed to temporal shifts among different types of ice‐algal blooms: long‐massive, short‐massive, long‐gentle, and short‐gentle bloom. The selected value for the maximum growth rate of the ice‐algal photosynthesis term is a key source for the inter‐model spreads. Understanding the simulated uncertainties on the pan‐Arctic and decadal scales is expected to improve coupled sea ice‐ocean ecosystem models. This step will be a baseline for further modeling/field studies and future projections.