Ship-based estimates of momentum transfer coefficient over sea ice and recommendations for its parameterization

Abstract. A major source of uncertainty in both climate projections and seasonal forecasting sea ice is inadequate representation surface–atmosphere exchange processes. The observations needed to improve understanding reduce surface parameterizations are challenging make rare. Here we present a large dataset ship-based measurements momentum (surface drag) the vicinity from Arctic Clouds Summer Experiment (ACSE) July–October 2014, Ocean 2016 experiment (AO2016) August–September 2016. combined provides an extensive record flux over wide range conditions spanning late summer melt early autumn freeze-up periods, atmospheric stabilities. Surface coefficients estimated situ eddy covariance measurements. local sea-ice fraction determined via automated processing imagery ship-mounted cameras. drag coefficient, CD10n, peaks at fractions 0.6–0.8, consistent with recent aircraft-based theory. Two state-of-the-art have been tuned our observations, providing excellent fits