SAR Observation of Waves under Ice in the Marginal Ice Zone

The marginal ice zone (MIZ) connects the open ocean and the pack ice, playing significant roles in shaping the ice edge and wave-ice interaction. Spaceborne synthetic aperture radar (SAR) has been demonstrated to be one of the most advantageous sensors for MIZ exploration given its capability to collect images under all weather conditions during day and night. In this study, we take advantage of the Sentinel-1 wave mode vignettes acquired around the Antarctic to quantify the image properties over MIZ. A data set of SAR images covering the ice edge with both open water and sea ice present in the same scene was created by manual inspection. It is found that the radar return over sea ice decreases by an average of approximately 1.78 dB in comparison to its adjacent open water, which is roughly independent of the polarizations and incidence angles. The long ocean waves are barely attenuated right across the ice edge in terms of their comparable azimuth cutoff. Further inside the ice from the edge, the waves are gradually dampened out at distances associated with their wavelengths. The results obtained in this study shall help interpret the radar scattering model validation as well as the wave-ice interaction.