InMotion: Influx of Momentum into the Arctic Ocean - Changes Associated with Sea Ice Reduction

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The PI proposes to study the surface wind based on reanalysis data, weighing theinfluence of the large-scale atmospheric circulation and local atmospheric boundary layer destabilization on its changes. Further, a budget including all variables in the sea ice momentum balance will be calculated using a state-of-the-art ice?ocean model. This enables the estimation of the individual effect of surface wind and ocean stresses, ice thickness, and ice concentration on the recently observed acceleration of the Arctic sea ice motion. Likely changes in the partitioning of air?sea and ice?sea stresses at the ocean surface due to the shrinkage of the ice area will be taken into account. For this purpose the model results will be validated with satellite data of ice concentration and ice drift. These findings will finally be combined into an integrative picture documenting and explaining the changes of the momentum flux into the Arctic Ocean during the past three decades. The proposed research will also aim to predict the future evolution of the momentum flux. Recently, it has been hypothesized that coupled global circulation models are incapable of correctly projecting trends in Arctic sea ice characteristics, perhaps because they lack dynamic feedback processes involving sea ice strength. The proposed work will aim to either disprove the hypothesis or understand the possible deficiencies of common sea ice models to represent such dynamic feedbacks.Increased momentum flux from the atmosphere to the Arctic Ocean can be expected to result in more vertical mixing, possibly bringing warmer waters from depth to near the sea surface where they may contribute to acceleration of the loss of sea ice. This study will enhance our ability to understand and predict the future changes in this momentum flux. Consequently, it contributes to our understanding and management of resource extraction, shipping, and ecosystem change in the Arctic, all of which depend on the evolution of the sea ice cover.