During this time period, PPI scans in azimuth were done at zenith, i.e. elevation was 90
degrees. This data is similar to vertically pointing data. However, if there is any
small unintended off-zenith radar misalignment, scanning in azimuth could impact the measured
mean Doppler velocity due to variations in the horizontal velocity component sampled as
part of the radial velocity measurement. In fact, the velocity data from these scans can
be used to diagnose any off-zenith component in the 'vertical' elevation.