CryoSat SAR-Mode Looks Revisited

The precision of sea-surface (or ice-surface) height measurements by radar altimetry improves in direct proportion to the square root of the number of statistically independent waveforms contributing to the measurement average. The closed-burst strategy used on CryoSat constrains the amount of averaging to be less than the theoretical limit by a factor of approximately three. Open-burst operation would allow the capture of nearly all available looks. Optimal performance requires that the radar pulse-repetition frequency be less than the usual Nyquist lower bound, which is acceptable for an altimeter viewing surfaces that have relatively small topographic relief.