Wave Attenuation Through an Arctic Marginal Ice Zone on 12 October 2015: 2. Numerical Modeling of Waves and Associated Ice Breakup
|Author(s)||Ardhuin Fabrice7, Boutin Guillaume1, Stopa Justin1, Girard-Ardhuin Fanny1, Melsheimer Christian2, Thomson Jim3, Kohout Alison4, Doble Martin5, Wadhams Peter6|
|Affiliation(s)||1 : Univ Brest, CNRS, IRD, Lab Oceanog Phys & Spatiale,IUEM,IFREMER, Brest, France.
2 : Univ Bremen, Inst Environm Phys, Bremen, Germany.
3 : Univ Washington, Appl Phys Lab, Seattle, WA 98105 USA.
4 : Natl Inst Water & Atmospher Res, Christchurch, New Zealand.
5 : PolarScientfic Ltd, Appin, Scotland.
6 : Cambridge Polar Consultants Ltd, Cambridge, England.
|Source||Journal Of Geophysical Research-oceans (2169-9275) (Amer Geophysical Union), 2018-08 , Vol. 123 , N. 8 , P. 5652-5668|
|WOS© Times Cited||27|
|Note||This article also appears in: Sea State and Boundary Layer Physics of the Emerging Arctic Ocean|
|Keyword(s)||wind-waves, sea ice, WAVEWATCH III, SAR, Beaufort, Arctic|
|Abstract||Many processes that affect ocean surface gravity waves in sea ice give rise to attenuation rates that vary with both wave frequency and amplitude. Here we particularly test the possible effects of basal friction, scattering by ice floes, and dissipation in the ice layer due to dislocations, and ice breakup by the waves. The possible influence of these processes is evaluated in the marginal ice zone of the Beaufort Sea, where extensive wave measurements were performed. The wave data includes in situ measurements and the first kilometer-scale map of wave heights provided by Sentinel-1 SAR imagery on 12 October 2015, up to 400 km into the ice. We find that viscous friction at the base of an ice layer gives a dissipation rate that may be too large near the ice edge, where ice is mostly in the form of pancakes. Further into the ice, where larger floes are present, basal friction is not sufficient to account for the observed attenuation. In both regions, the observed narrow directional wave spectra are consistent with a parameterization that gives a weak effect of wave scattering by ice floes. For this particular event, with a dominant wave period around 10 s, we propose that wave attenuation is caused by ice flexure combined with basal friction that is reduced when the ice layer is not continuous. This combination gives realistic wave heights, associated with a 100-200 km wide region over which the ice is broken by waves, as observed in SAR imagery.|