Jullian C.B. Williams , Stephen F. Ackley , Alberto Mestas-Nunez, Grant Macdonald, Stefanie Arndt

During the summer months in the Antarctic, perennial and seasonal sea ice floes flood. Flooding is caused by snow at the surface weighing down the ice, causing a negative freeboard and flooding the basal snow layer with seawater. This creates a brine-slush layer. Alternatively, or simultaneously, meltwater can percolate through the snow and flood the surface of the ice floe. The appearance of these flooded ice floes changes dramatically in synthetic aperture radar (SAR) scenes with season and as the dielectric constant changes with brine content. In addition to this, the incident look angle of the radar imager affects the returned backscatter intensity across the scene.
The Sentinel-1 instrument began collecting data with its S1A instrument in 2014 and later S1B in 2016 and continues to acquire SAR data across the globe. Sentinel-1 supplies an unprecedented, dual-band look at sea ice in the North and South poles to understand the dynamics of sea ice processes during polar nighttime. The satellite instrument provides a unique opportunity to study the signal attenuations and the subsequent backscatter intensities in the SAR scene that change with seasonal ice flooding. This paper uses the Sentinel-1 radar data to understand the changes in backscatter intensity in flooded floes in the Amundsen, whose changes in floe flooding show spatial and spectral changes throughout the seasons.