The purpose of the CryoSat SARIn mode is to directly determine the across-track angle offset of the returning echo (by using the phase difference between the 2 antennas). In the Level 2 SARIn data, the 20 Hz latitude and longitude values provide the estimated position of the return (as computed from the phase difference) and not the nadir. The nadir location is only present in the Level 2 data at 1 Hz.

However, it is important to note that over areas of rough terrain and steep surface slopes, when the across-track offset is large, it is common for phase wrapping to occur. This will cause the echo to appear to come from the other side of the ground track and will produce erroneous surface height measurements. In L2 SARIn products the X-track angle error flag (one of the L2 Quality Flags (flag_quality_20_ku)) is used to detect these erroneous measurements by comparing the computed surface measurements to the DEM. The error flag is set when the difference between the computed surface elevation and the DEM is greater than 50m, and therefore phase-wrapping is assumed to have occurred. However, DEMs are only available for Greenland and Antarctica. For data in other locations, where a sequence of records shows an increasing across-track offset and then an abrupt switch to the other side of the track, it is likely that phase-wrapping has occurred. On the contrary, if the records cluster to one side of the track, they are likely to be good returns without phase-wrapping.

In L2I SARIn products the Ambiguity Indicator flags are also used to indicate where the interferometric angle may be ambiguous due to phase wrapping.