PIRAQ Synchronization Error

S-Pol IHOP_2002, Oklahoma Panhandle
May/Jun 2002

In about one-quarter to one-third of all .5° surveillance scans, an artifact exists. This artifact is associated with a limited ability of the S-Pol PIRAQ signal processor to respond quickly to changes in scan parameters. For IHOP particularly, a routine scan sequence included transition from a 0.0° SUR tilt with 64 samples per beam, to a 0.5° tilt with 110 samples per beam. This would cause the signal processor to have trouble synchronizing during the introduction of the new parameters, and you get a set of beams with a "barber pole" pattern, or a "stutter". The problem extends through the active range of the clutter filter (out to 120 km).

In the image shown, the artifact is seen at about 290° azimuth. Parameters shown are reflectivity (dBZ) and velocity (m/s).

Occurrences of the PIRAQ stutter might affect any automated processing of S-Pol data, and should be either removed with an editor prior to running such automated processes, or removed by that automated process. Further work should be done to characterize the nature of the stutter, and select or design a parameter that can be used for "stutter filtering".

--- Bob Rilling --- / NCAR Atmospheric Technology Division
Created: Thu Oct 31 14:21:03 MST 2002
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