How well does wind speed predict airâ€sea gas transfer in the sea ice zone? A synthesis of radon deficit profiles in the upper water column of the Arctic Ocean

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Loose, Brice, Kelly, Roger P., Bigdeli, A., Williams, W., Rutgers van der Loeff, M., Moran, S. B.
• Format: Text
• Language: unknown
• Published: DigitalCommons@URI 2017
• Subjects: Arctic Ocean; Beaufort Sea; Sea ice
• Online Access: https://digitalcommons.uri.edu/gsofacpubs/610; https://doi.org/10.1002/2016JC012460; https://digitalcommons.uri.edu/context/gsofacpubs/article/1575/viewcontent/Loose_etal_HowWellDoes_2017.pdf

We present 34 profiles of radonâ€deficit from the iceâ€ocean boundary layer of the Beaufort Sea. Including these 34, there are presently 58 published radonâ€deficit estimates of airâ€sea gas transfer velocity (k) in the Arctic Ocean; 52 of these estimates were derived from water covered by 10% sea ice or more. The average value of k collected since 2011 is 4.0 ± 1.2 m d−1. This exceeds the quadratic wind speed prediction of weighted kws = 2.85 m d−1 with meanâ€weighted wind speed of 6.4 m s−1. We show how ice cover changes the mixedâ€layer radon budget, and yields an “effective gas transfer velocity.†We use these 58 estimates to statistically evaluate the suitability of a wind speed parameterization for k, when the ocean surface is ice covered. Whereas the six profiles taken from the open ocean indicate a statistically good fit to wind speed parameterizations, the same parameterizations could not reproduce k from the sea ice zone. We conclude that techniques for estimating k in the open ocean cannot be similarly applied to determine k in the presence of sea ice. The magnitude of k through gaps in the ice may reach high values as ice cover increases, possibly as a result of focused turbulence dissipation at openings in the free surface. These 58 profiles are presently the most complete set of estimates of k across seasons and variable ice cover; as dissolved tracer budgets they reflect airâ€sea gas exchange with no impact from airâ€ice gas exchange.