Impacts and mitigation of ground clutter on S-band dual-polarimetric radar data

Ground clutter contamination is a long term problem in radar meteorology. The case of ground clutter overlaid with weather echoes is particularly difficult to identify and mitigate. Although the advent of dual-polarimetric radar measurements has resulted in improved ground clutter identification, several dual-polarimetric variables are, in fact, more severely impacted by ground clutter. In this study ground clutter mixed with weather echoes resulting in various clutter to signal ratio (CSR) values are simulated over numerous conditions in order to determine the errors in dual-polarimetric variables due to clutter. It turns out that, in certain circumstances, significant errors in differential reflectivity can occur at CSR values as low as -20 dB (i.e. the clutter is 20 dB weaker than the overlying weather echo). Modeling results of the impact of ground clutter and the WSR-88D ground clutter filter will be shown for differential reflectivity and co-polar correlation coefficient.

Further, the dual-polarimetric variables are incorporated into the Clutter Mitigation Decision (CMD) algorithm that currently operates on the WSR-88D network. Improvements in ground clutter mitigation will be shown with the inclusion of the dual-polarimetric variables into CMD. Further it will be shown how well the dual-pol CMD identifies clutter at different CSR values as compared to the conditions the modeling results indicate significant contamination of the weather data by overlying clutter.