Nondimensional parameter regimes of Arctic ice keel-ocean flow interactions and internal wave drag

Abstract. Sea ice keels influence momentum transfer between the drifting ice cover and the upper ocean, yet their effects remain difficult to represent in large-scale models. When keels move relative to the stratified ocean, they can generate internal waves that contribute an additional drag and modify upper-ocean energetics. We examine the parameter space governing ice keel–ocean interactions by reformulating an existing internal wave drag framework in terms of four nondimensional parameters that quantify lee wave radiation, flow nonlinearity, stratification strength, and the depth of the keel relative to the mixed layer. Using output from a pan-Arctic coupled sea ice–ocean model, we apply Gaussian Mixture Modeling to these parameters to identify statistically coherent regimes across the Arctic for annual, summer, and winter conditions. The resulting regimes exhibit clear spatial organization and pronounced seasonal variability. To interpret their dynamical significance, we perform idealized numerical simulations for representative parameter combinations and analyze kinetic energy dissipation and propagation of internal waves below the pycnocline. The simulations indicate that deep and steep keels beneath perennial sea ice, in particular in the summer when the mixed layer is shallow, enhance dissipation around and below the pycnocline. Comparison with existing parameterizations further suggests that regimes characterized by strong nonlinearity or shallow mixed layers may be not well-represented. These results provide a framework for constraining physically relevant parameter regimes for ice keel drag and inform future model development and observational studies of ice–ocean coupling.