Monitoring the Performance of the Polarimetric WSR-88D–Calibration and Sensitivity

The US NEXRAD WSR-88D (Weather Surveillance Radar – 1988 Doppler) was upgraded for  polarimetric capability in 2013.  Engineers and scientists at the WSR-88D Radar Operations Center (ROC), along with members of the National Center for Atmospheric Research (NCAR) and the National Severe Storms Laboratory (NSSL), have established a program using external targets to monitor system calibration. The team has investigated the variability of the external targets including light rain, dry snow/ice phase, and Bragg scatter. The monitoring program includes extensive use of solar scans for establishing antenna performance metrics and receive path calibration.  This paper discusses the relative accuracy of the various methods used for enhancing the calibration state of the polarimetric data delivered by the WSR-88D.  This paper will also present the ROC team’s assessment of the sensitivity performance of the upgraded radar.