Principles and applications of dual-polarization weather radar. Part I: Description of the polarimetric radar variables

The United States Weather Surveillance Radar-1988 Doppler (WSR-88D) radar network has been upgraded to dual-polarization capabilities, providing operational and research meteorologists with a wealth of new information regarding the types and distributions of hydrometeors within precipitating storms, as well as a means for improved radar data quality. In addition to the conventional moments of reflectivity factor at horizontal polarization (Z H ), Doppler velocity (V r ), and Doppler spectrum width (W), the new variables available from upgraded radars are the differential reflectivity (Z DR ), differential propagation phase shift ( DP ), specific differential phase (K DP ), and the co-polar correlation coefficient ( hv or CC). In the first part of this review series, a description of the polarimetric radar variables available from the newly polarimetric WSR-88D radars is provided. An emphasis is made on their physical meaning and interpretation in the context of operational meteorology.