Dual-Polarized Radar Coverage in Terminal Airspaces and Its Effect on Interpretation of Winter Weather Signatures: Current Capabilities and Future Recommendations

This is a feasibility study on the use of dual-polarized radars to infer icing in Terminal Air Spaces (TASs) of commercial airports. The amount/quality of radar coverage in each TAS is quantified as a function of its location, traffic, and vulnerability to icing. Though there are some exceptions, most high-traffic or high-icing airports have comparatively good coverage. A major limitation for icing detection is anomalous propagation as most events had an inversion below the top of the TAS. This leads to overestimates in the elevation where icing layers exist and significant contamination from ground clutter. The effects of beam broadening on the radar's ability to resolve key microphysical signatures shows that at most airports dendrite growth and melting can only be resolved in part of the TAS part of the time. Because most airports have coverage from multiple radars, use of a three-dimensional mosaic was investigated. This does partly mitigate some resolution issues, but the maxima within individual layers are somewhat reduced in the interpolation process. Also, there can be a gap in coverage between the ground and the lowest vertical layer in the mosaic leading to an absence of data in the near-ground environment. A series of recommendations are made to address the concerns raised by this investigation. These include using only icing tops (not bottoms) to identify areas of icing, use of data mining to retrieve precipitation echo in the presence of ground clutter, and including the beamwidth in radar mosaics.