Principles of Dual-polarization Upgrade and Calibration for the WSR-88D Radars

Since the introduction of the linear dual-polarization measurements of precipitation in the late seventies, these observations have come a long way that the nation wide weather surveillance radars are being upgraded to dual-polarization. While dual-polarization has been around for a while with research radars, only recently it is starting to make way into the operational applications. Some of the processes and techniques used in the maintenance and calibration of the individual research radars may not scale to large number of operational systems.

This paper presents principles associated with the implementation of the dual-polarization upgrade for the weather service surveillance radars. The dual-polarization upgrade also provides some opportunities in the upgrades of the some of the radar subsystems, which are presented. Dual-polarization calibration and maintenance are important aspects of the upgrade. Elaborate and careful procedures have been introduced to calibrate the differential reflectivity to very high accuracy and these procedures are described. Accurate error budget analysis of the reflectivity and differential reflectivity calibration procedures are also presented.