SWOT observations over sea ice: a first look

We present a first examination of observations from the Surface Water and Ocean Topography (SWOT) mission over the polar oceans. In SWOT, bright, quasi-specular leads are associated with lower heights relative to the surrounding ice cover. Surface heights and freeboard from SWOT and ICESat-2 are compared in two near-coincident segments in the Beaufort and the Weddell Seas. Correlations and mean differences between these 30-km ICESat-2 and SWOT height segments are 0.91 (0.02±0.08m) in the Beaufort and 0.65 (0.01±0.09m) in the Weddell. Differences in freeboards using minimum height as a reference sea surface are 0.04±0.08m and -0.01±0.09m; minimum heights are localized within the same lead features of the two segments. The SWOT wide-swath radar altimeter can, for the first time, provide two-dimensional mappings of the spatial variability of freeboard and ice thickness — crucial information that will enhance our understanding of the physical mechanisms driving the decline of sea ice covers.