Finely resolved along-track wave attenuation estimates in the Antarctic marginal ice zone from ICESat-2

Abstract. Advances in our modelling capacity of wave–ice interactions are hindered by the limited availability of wave observations in sea ice and, specifically, under a broad range of wave and sea ice conditions. Satellite remote sensing provides opportunities to vastly expand the observational dataset of waves in sea ice and the study of wave–ice interactions. Specifically, Brouwer et al. (2022) demonstrated a clear reduction in observed wave energy into the Antarctic Marginal Ice Zone (MIZ) as derived from ICESat-2 observations. Here, we build upon the work of Brouwer et al. (2022) to estimate the wave attenuation rate in the Antarctic MIZ under a wide variety of sea ice conditions. Overall statistics of the observations reveal a linear increase in the wave attenuation rate with relative distance into the MIZ, implying that the wave energy in the MIZ scales as ∼exp (βx2…), where β is a frequency-dependent attenuation coefficient. Attenuation rates are well sorted with wave frequency, where the highest attenuation rates are observed for the shortest waves. We find that both the magnitude and the frequency dependence of the ICESat-2-estimated wave attenuation rates are consistent with in situ observations. We further highlight that the misalignment between the incident wave direction and the measurement transect, as well as the inhomogeneity of the ice pack, may lead to significant local fluctuations and negative values in the estimated wave attenuation rate when evaluating individual transects. The strong dependence of the overall statistics of the wave attenuation rate on the wave frequency and the relative distance into the MIZ alone provides significant opportunities in modelling wave–ice interactions in the Antarctic environment at global and climate scales, as it does not depend on system variables that are not straightforward to measure, retrieve, or simulate at such large scales. However, independent parameterization of the MIZ width will be required to do so.