The CryoSat interferometer: End-to-end calibration and achievable performance

Exploiting the interferometric capability of CryoSat, the interferometric phase related to the first arrival of the echo is used to retrieve the angle of arrival of the scattering in the across-track direction. This paper presents an assessment of the achievable end-to-end performance for the across-track angle that is retrieved by the CryoSat SARin acquisitions. In orbit calibration campaigns are periodically performed to monitor the performance and to calibrate the interferometer. We started from the analysis of the data acquired during the interferometer calibrations campaigns to verify if the current performance of CryoSat is in line with the system requirements. The analysis revealed that the interferometric measurements of CryoSat are exceeding the expected performance and that, by proper processing, it is possible to achieve further improvements for the accuracy on the retrieved across-track angle.