Comparing observations and parameterizations of ice-ocean drag through an annual cycle across the Beaufort Sea

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Brenner, S., Rainville, L., Thomson, J., Cole, S., & Lee, C. Comparing observations and parameterizations of ice-ocean drag through an annual cycle across the Beaufort Sea. Journal of Geophysical Research: Oceans, 126(4), (202): 1e2020JC016977, https://doi.org/10.1029/2020JC016977.Understanding and predicting sea ice dynamics and ice-ocean feedback processes requires accurate descriptions of momentum fluxes across the ice-ocean interface. In this study, we present observations from an array of moorings in the Beaufort Sea. Using a force-balance approach, we determine ice-ocean drag coefficient values over an annual cycle and a range of ice conditions. Statistics from high resolution ice draft measurements are used to calculate expected drag coefficient values from morphology-based parameterization schemes. With both approaches, drag coefficient values ranged from ∼1 to 10 × 10−3, with a minimum in fall and a maximum at the end of spring, consistent with previous observations. The parameterizations do a reasonable job of predicting the observed drag values if the under ice geometry is known, and reveal that keel drag is the primary contributor to the total ice-ocean drag coefficient. When translations of bulk model outputs to ice geometry are included in the parameterizations, they overpredict drag on floe edges, leading to the inverted seasonal cycle seen in prior models. Using these results to investigate the efficiency of total momentum flux across the atmosphere-ice-ocean interface suggests an inter-annual trend of increasing coupling between the atmosphere and the ocean.This work was supported by the Office of Naval Research as part of the Stratified Ocean Dynamics of the Arctic (SODA) research project. Funding was through grant numbers N00014-16-1-2349, N00014-14-1-2377, N00014-18-1-2687, and N00014-16-1-2381