Dual-Scan and Dual-Polarization Measurements to Detect Ground Clutter mixed with Weather Signals

Ground clutter contamination is a long-standing problem in radar meteorology because of the bias it brings to the weather estimates. In order to avoid the potential bias caused by the ground clutter filter, an efficient way is to first detect the locations of ground clutter and then apply ground clutter filter on those contaminated gates. Polarimetric radars provide additional measurements that allow better characterization of the targeted medium. Because ground clutter has very different polarimetric characteristics from weather echoes, the dual-polarization measurements can be used to distinguish one from the other. The commonly used polarimetric discriminants are the copolar correlation coefficient ρhv, differential reflectivity ZDR, and differential phase ϕDP. The polarimetric discriminants work well in detecting ground clutter, but there are still substantial miss-detections and false alarms. Scan-to-scan correlation of weather radar signals is recently introduced to identify ground clutter. It takes advantage of the fact the correlation time of radar signals from hydrometeors is typically much shorter than that from ground objects. In this work, we combine the I/Q data from the dual-scan and dual-polarization measurements, and use a test statistic obtained from the Generalized Likelihood Ratio Test (GLRT) to determine the existence of ground clutter. Its performance is evaluated using data collected by the WSR-88D KOUN 10-cm polarimetric radar.