In many areas of the country, particularly in the west, the quality of the data from the WSR-88D radars is significantly impacted by terrain features in the vicinity of the radar. These impacts fall into two general categories: ground clutter returns, and obscured radar coverage. Ground clutter returns occur when terrain features are high enough with respect to the radar to protrude into the radar beam propagation path. Although the WSR-88D radar has clutter suppression capabilities, there are many cases where ground clutter returns appear in WSR-88D radar products. A secondary problem that results from applying clutter filters to the radar data is that some low-velocity weather returns may be suppressed by the clutter filters. Obscured radar coverage is also a direct result of the terrain features that cause the ground clutter returns. Down-range of these terrain features radar coverage is either partially or completely obscured due to the effects of terrain blockage of the beam. Significant weather can occur undetected in these obscured areas.

This paper will describe the results of a study being conducted by Unisys Weather Information Services to investigate techniques for using terrain elevation information to identify regions of the radar coverage area where ground clutter returns can occur, and to identify obscured radar coverage areas. The primary objective of this study is to develop a set of automated techniques for generating radar mosaic products that utilize terrain elevation information in assigning confidence levels to individual radar contributors in regions where mosaic bins fall within the coverage areas of multiple radars.