Real time mitigation of anomalous propagation clutter

Mitigation of anomalous propagation clutter (AP) is an ongoing problem in radar meteorology. AP clutter routinely contaminates radar data masking weather returns causing poor data quality. The problem is typically mitigated by clutter filtering all radar data but this will also eliminate weather data at zero velocity. With the advent of fast digital receivers capable of real time spectral processing, the real time identification and elimination of AP clutter is now possible. A fuzzy logic algorithm is used to distinguish between clutter echo and precipitation echoes. Based on this classification, clutter filters can be applied to only those radar resolution volumes where clutter is present, in real time. In this way weather echoes are preserved while clutter echoes are mitigated. The clutter filters used in this paper are spectral based, i.e., they are applied in the spectral domain. In many cases, after the clutter echoes are filtered, the underlying weather echo signatures are revealed thereby significantly increasing the visibility of weather echo. This paper describes the Fuzzy Logic algorithm for clutter echo identification and the technique is illustrated with experimental data from S-Pol, NCAR’s (National Center for Atmospheric Research) S-band polarimetric radar.