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© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Elementa Science of the Anthropocene 5 (2017): 55, doi:10.1525/elementa.241., 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. In this study, continuous observations in the Canada Basin from March through December 2014 were used to investigate spatial differences and temporal changes in under-ice roughness and momentum transfer as the ice cover evolved seasonally. Observations of wind, ice, and ocean properties from four clusters of drifting instrument systems were complemented by direct drill-hole measurements and instrumented overhead flights by NASA operation IceBridge in March, as well as satellite remote sensing imagery about the instrument clusters. Spatially, directly estimated ice-ocean drag coefficients varied by a factor of three with rougher ice associated with smaller multi-year ice floe sizes embedded within the first-year-ice/multi-year-ice conglomerate. Temporal differences in the ice-ocean drag coefficient of 20–30% were observed prior to the mixed layer shoaling in summer and were associated with ice concentrations falling below 100%. The ice-ocean drag coefficient parameterization was found to be invalid in September with low ice concentrations and small ice floe sizes. Maximum momentum transfer to the ice occurred for moderate ice concentrations, and transfer to the ocean for the lowest ice concentrations and shallowest stratification. Wind work and ocean work on the ice were the dominant terms in the kinetic energy budget of the ice throughout the melt season, consistent with free drift conditions. Overall, ice topography, ice concentration, and the shallow summer mixed layer all influenced mixed layer currents and the transfer of momentum within the air-ice-ocean system. The observed changes in momentum transfer show that care must be taken to determine appropriate parameterizations of momentum transfer, an, The deployment of the ITP-Vs and the subsequent analysis effort was supported by the Office of Naval Research under grants N00014-12-10140 and N00014-12-10799.

A comprehensive set of autonomous, ice-ocean measurements were collected across the Canada Basin to study the summer evolution of the ice-ocean boundary layer (IOBL) and ocean mixed layer (OML). Evaluation of local heat and freshwater balances and associated turbulent forcing reveals that melt ponds strongly influence the summer IOBL-OML evolution. The areal expansion and drainage of melt ponds resulted in a substantial increase in upper ocean heat storage (39 MJm-2) and development of the summer mixed layer and near-surface temperature maximum (NSTM). 1-D boundary layer model results show that melt pond drainage provided sufficient buoyancy to the summer halocline to prevent subsequent wind events from mixing out the NSTM. Ice Camp observations captured the development of a second shallower NSTM in late summer; however, meltwater contributions were inadequate to sustain this feature when winds increased. In the marginal ice zone (MIZ), thermal heterogeneities in the upper ocean led to large ocean-to-ice heat fluxes (100–200 Wm-2) and enhanced basal ice melt (3–6 cm-day-1). Calculation of the upper ocean heat budget shows that the extensive area of deteriorating sea ice observed away from the ice edge during the 2014 season, termed the thermodynamically forced MIZ, was driven primarily by local solar radiative heat input. .