Title: Ice and ocean velocity in the Arctic: near-inertial to seasonal timescales
Abstract: The interplay between sea ice concentration, sea ice roughness, ocean stratification, and momentum transfer to the ice and ocean is subject to seasonal and decadal variations that are crucial to understanding the present and future air-ice-ocean system in the Arctic. Continuous observations in the Canada Basin from March through December 2014 were used to investigate spatial differences and temporal changes in under-ice roughness, low-frequency momentum transfer, and near-inertial motions of the ice and mixed layer as well as the internal wave field. Ice-ocean drag coefficients exhibited spatial differences of a factor of three and temporal differences of 20-30% related to the size of multi-year ice floes and changes in ice concentration. Maximum momentum transfer to the ice occurred for moderate ice concentrations, and transfer to the ocean for the lowest ice concentrations and shallowest stratification. For the internal wave field, three different ice concentration thresholds were important: 1) the initial decrease from 100% ice concentration, 2) the transition to 70-80% ice concentration, and 3) the transition to open water. Ice roughness influenced internal wave properties for ice concentrations greater than approximately 70-80%. The importance of both ice roughness and ice concentration complicates future predictions of ice motion, mixed layer currents, internal wave activity and vertical mixing. Implications for the future Arctic are discussed.
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