Ground clutter mitigation for S-band dual-polarimetric radars

The identification and mitigation of anomalous propagation (AP) and normal propagation (NP) clutter is an ongoing problem in radar meteorology. Scatter from ground clutter targets routinely contaminate radar data and mask weather returns causing poor data quality. To mitigate ground clutter contamination, two fuzzy logic algorithms (single polarization and dual-polarization), referred to as Clutter Mitigation Decision (CMD), have been developed to distinguish between clutter echoes and precipitation echoes. Subsequently a clutter filter is applied to those radar resolution volumes where clutter is present and the radar moments computed from this selectively clutter filtered data. In this way zero velocity weather echoes are preserved while clutter echoes are mitigated. The single polarimetric version of CMD is currently scheduled to be deployed on the National Weather Service operational radar network, Weather Surveillance Radar 1988 Doppler (WSR-88D) beginning in the spring of 2009.

The NEXRAD radar network will be upgraded to include dual-polarimetric data in the future and the dual-polarimetric variables can significantly aid in the identification of ground clutter. However, the quality of dual-polarimetric measurements can be impacted in mixed clutter and weather situations with clutter to signal ratio (CSR) values down to –10 dB. This study examines the performance of the dual-polarimetric CMD algorithm and the input variables in mixed clutter and weather situations and quantifies the performance as a function of CSR using experimental data and data generated by overlaying the time-series of pure weather and pure clutter. Additional time-series variables are examined for their utility in identifying the presence of ground clutter mixed with weather echoes.