Multi-peak Retracking of CryoSat-2 SARIn Waveforms Over Arctic Sea Ice

CryoSat-2 (CS2) is the first mission equipped with a pulse-limited radar altimeter capable of operating in Synthetic Aperture Radar (SAR) Interferometric (SARIn) mode. Over ice sheets and caps, CS2 SARIn data have been used to retrieve surface elevations over an across-track ground “swath.” This work demonstrates that retracking multiple coherent peaks waveforms, combination interferometric phase, enables obtain more than one valid height estimate from single waveforms Arctic sea ice. For some scattering at satellite nadir successfully separated returns originating off-nadir leads. An average bias -1.8 cm found for absolute when using 50% threshold retracker. It shown including associated phase difference processing does not introduce any on freeboard heights compared estimates regular SAR schemes, while significantly increasing number retrievals (+55%) coastal domain multi-year regions (~3 times). results ~34% reduction gridded random uncertainty, corresponding ~20% total thickness uncertainty. The this show acquisitions provide improved spatial coverage denser sampling level mode, accuracy being largely driven by algorithm.