Processing and Interpretation of Coherent Dual-Polarized Radar Measurements

Abstract

Dual-polarized coherent radar measurements are used to estimate the differential propagation phase or ?DP between horizontal and vertical polarization states. The slope of ?DP is an estimate of the specific differential phase KDP. This process is complicated due to differential phase on backscatter δ between horizontal and vertical polarization states, which can be significant at C band. Filtering techniques are presented for separating δ from propagation phase and then estimating KDP and δ. Also discussed are procedures for the estimation and interpretation of other radar measurables such as conventional radar reflectivity, differential reflectivity ZDP, the magnitude of the copolar correlation coefficient ?HV(0), and Doppler spectrum width σ?. A low noise level is essential for accurate estimation of these parameters. A spectral domain technique that can eliminate some of the noise contained in radar time series data is presented. The techniques are applied to data collected by Poldirad, the German Aerospace Research Establishment's polarimetric C-band radar.