Simulated effects of a snow layer on retrieval of CryoSat-2 sea ice freeboard

The impact of a snow layer on the location of the tracking point (RP) for ranging to the sea ice surface in CryoSat-2 synthetic aperture interferometric radar altimeter waveforms is simulated. With a range resolution of similar to 47 cm, the response of the air-snow (a-s) interface broadens the response of the snow-ice (s-i) interface and displaces the RP toward the altimeter. This effect is largest when the strengths of their returns are comparable and when snow thicknesses are > 20 cm. On the other hand, the RP is displaced away from the altimeter when the reduced propagation speed in the snow layer is not accounted for. This analysis examines the dependence of these competing corrections on snow thickness and the relative scattering strengths of the interfaces and the sensitivity of two different tracking approaches (leading edge and centroid) to these snow parameters. Expected errors depend on a better understanding of the relative scattering strengths of the interfaces and snow layer.