Estimates of wave attenuation from ICESat-2 observations

Energetic waves originating from the Southern Ocean can propagate great distances into the Antarctic ice pack. Along the way, they can significantly alter the composition of the ice whilst, at the same time, sea ice can significantly alter the characteristics of the wave field. Importantly, sea ice attenuates wave energy, thereby reducing their capacity to break the ice. Understanding of the rate of attenuation of wave energy in sea ice is thus critical to achieve accurate representation of sea ice in operational forecasting models. Observations of wave attenuation are, however, sparse as logistics to the harsh and remote Antarctic Marginal Ice Zone are limited. To this end, satellite remote sensing provides significant opportunities as it can cover large spatial areas, albeit at relatively low temporal resolution. Recent studies have shown the capabilities of ICESat-2 to not only measure surface height over land, ocean and sea ice at high accuracy, but also to distill wave field properties from these observations. Here, we use the quality-controlled data of Brouwer et al. (2022) to estimate the wave attenuation rate from ICESat-2 observations. We show that the magnitude of the estimated attenuation rates from ICESat-2 observations are largely consistent with those observed by others. As ICESat-2 provides a near-instantaneous snapshot of waves in sea ice, the data reveals unique spatial resolution of the attenuation rates across the Marginal ice Zone that cannot easily be obtained with surface buoys. Spatial variability of the estimated attenuation rates appears to be correlated with sea ice properties obtained from satellite derived products, such as sea ice thickness and sea ice concentration.