Attenuation of ocean surface waves in pancake and frazil sea ice along the coast of the Chukchi Sea

Hosekova, L., Malila, M. P., Rogers, W. E., Roach, L. A., Eidam, E., Rainville, L., Kumar, N. and Thomson, J. (2020) Attenuation of ocean surface waves in pancake and frazil sea ice along the coast of the Chukchi Sea. Journal of Geophysical Research: Oceans, 125 (12). e2020JC016746. ISSN 2169-9275 doi: 10.1029/2020JC016746

Abstract/Summary

Alaskan Arctic coastlines are protected seasonally from ocean waves by the presence of coastal and shorefast sea ice. This study presents field observations collected during the autumn 2019 freeze up near Icy Cape, a coastal headland in the Chukchi Sea of the Western Arctic. The evolution of the coupled air-ice-ocean-wave system during a four-day wave event was monitored using drifting wave buoys, a cross-shore mooring array, and ship-based measurements. The incident wave field with peak period of 2.5 s was attenuated by coastal pancake and frazil sea ice, reducing significant wave height by 40\% over less than 5 km of cross-shelf distance spanning water depths from 13 to 30 m. Spectral attenuation coefficients are evaluated with respect to wave and ice conditions and the proximity to the ice edge. Attenuation rates are found to be three times higher within 500 m of the ice edge, relative to values farther in the ice cover. Attenuation coefficients are in the range of $\langle 2.3,2.7\rangle$ \si{\meter^{-1}}, and follow a power-law dependence on frequency.