Differential Reflectivity Calibration for the WSR-88D

The Radar Operations Center (ROC) is supporting the development and deployment of a polarimetric upgrade to the Nation's WSR-88D Doppler weather radar network. This deployment should be completed in 2013. A key technical challenge has been providing for accurate differential reflectivity calibration. The uncertainty of this calibration must be held to within 0.1 dB to obtain maximum benefits from dual polarization. ROC engineers have been working with scientists and engineers at the National Center for Atmospheric Research (NCAR) to develop and implement an end-to-end calibration method based on the concept of cross polarization power (CPP). NCAR has shown the CPP method to be equivalent to the classical vertical pointing (VP) method, which has long been considered the standard. This paper presents a technical explanation and current status of the CPP method as it is adapted to the WSR-88D.