Estimates of dissipation of wave energy by sea ice for a field experiment in the Southern Ocean, using model/data inversion

A model-data inversion is applied to a very large observational dataset collected in the Southern Ocean north of the Ross Sea during late autumn to early winter, producing estimates of the frequency-dependent rate of dissipation by sea ice. The modeling platform is WAVEWATCH III (R) which accounts for non-stationarity, advection, wave generation, and other relevant processes. The treatment of wave generation by wind in partial ice cover is, however, a major source of uncertainty, so the inversion is run using two assumptions, bounding the unknown optimal representation. The resulting dissipation profiles (9477 for each inversion) are co-located with other variables such as ice thickness to quantify correlations which might be exploited in later studies to improve predictions. The mean dissipation profile from each inversion is fitted to a simple polynomial. Variability about these mean profiles is not small, but they show remarkable qualitative similarity to prior observation-based estimates of dissipation, and are consistent with at least two theoretical models, one of which assumes that dissipation is dominated by turbulence generated by shear at the ice-water interface.