Sensitivity of CryoSat-2 Arctic sea-ice freeboard and thickness on radar-waveform interpretation

Abstract. In the context of quantifying Arctic ice-volume de-crease at global scale, the CryoSat-2 satellite was launched in 2010 and is equipped with the Ku band synthetic aper-ture radar altimeter SIRAL (Synthetic Aperture Interfero-metric Radar Altimeter), which we use to derive sea-ice free-board defined as the height of the ice surface above the sea level. Accurate CryoSat-2 range measurements over open water and the ice surface of the order of centimetres are necessary to achieve the required accuracy of the freeboard-to-thickness conversion. Besides uncertainties of the actual sea-surface height and limited knowledge of ice and snow properties, the composition of radar backscatter and there-fore the interpretation of radar echoes is crucial. This has consequences in the selection of retracker algorithms which are used to track the main scattering horizon and assign