Impact of Receiver Saturation on Surface Doppler Velocity Measurements From the EarthCARE Cloud Profiling Radar

Antenna-pointing techniques that rely on Earth´s surface Doppler velocity measurements are expected to play a crucial role in enabling antenna mispointing corrections in spaceborne radar systems. Here, the impact of the EarthCARE cloud profiling radar (CPR) receiver saturation on the quality of the surface Doppler velocity measurements is discussed. The CPR linear receiver is expected to saturate always from surface echoes. Our results based on an I/Q simulation framework show that for the EarthCARE radar configuration: 1) biases introduced by saturation will be negligible; 2) the standard deviation of the velocity estimates will increase by 30-50% when moving from unsaturated to completely saturated surface return for a corresponding pulse repetition frequency in the range between 6.1 and 7.5 kHz. As a consequence longer integration times will be necessary to achieve the same accuracy in presence of complete saturation.