87th AMS Annual Meeting

Thursday, 18 January 2007: 11:30 AM
A Method to Reduce the Clutter Filter Induced Data Bias by Improving the Vertical Application of WSR-88D Bypass Maps
217A (Henry B. Gonzalez Convention Center)
Joe N. Chrisman, NOAA/NWS, Norman, OK; and C. A. Ray
The legacy Weather Surveillance Radar-1988, Doppler (WSR-88D) Radar Data Acquisition (RDA) only supported two bypass maps (one for each elevation segment): the Elevation Segment 1 map controlled clutter suppression application for all tilts less than or equal to 1.65 degrees (split cut processing) and the Elevation Segment 2 map was used for all elevations above 1.65 (batch mode and contiguous Doppler elevations up to and including 19.5). This limitation resulted in a bypass map for the particular elevation segment which is dominated by clutter from the lowest elevation of the particular segment (worst clutter coverage). This map is used for all volume coverage pattern tilts in that segment, regardless of how the clutter horizon changed with increasing elevation. By contrast, the newly-deployed Open RDA (ORDA) supports the definition and application of up to five elevation segments, each with its own bypass map. Implementing five elevation segment definitions, with their respective bypass maps, tailors the application of clutter suppression to the changes in the radar's clutter horizon with increasing elevation angle. WSR-88D examples will be used to demonstrate how increasing the number of elevation segment definitions reduces the clutter filter induced data bias caused by over-suppression, especially in the batch mode processing.

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