The Terminal Doppler Weather Radar (TDWR) velocity dealiasing routine has failed repeatedly when the squall-line wind opposed the ambient wind. Consequently, gust fronts are not detected in these cases, which also pose an aviation safety hazard. Several problems with the TDWR velocity dealiasing routine have been identified and corrected using a suite of four data cases from Memphis (MEM), Chicago (ORD), and Oklahoma City (Program Support Facility).
Modifications to the TDWR velocity dealiasing algorithm include: (1) lowering the Velocity Azimuth-Display (VAD) symmetry fit parameter from 10 to 0.1, (2) for a given sample volume, requiring valid radial velocities for the dual PRF scans (scans 2 and 3) to produce a valid fully conditioned radial velocity on scan 3, and (3) reinitializing the wind field model every volume scan.
Lowering the VAD symmetry fit parameter from 10 to 0.1 enables a VAD fit in a uniform wind environment while disabling the VAD fit when squall-line winds oppose environmental winds.
Requiring valid radial velocities for the dual PRF scans (scans 2 and 3) to produce a valid fully conditioned radial velocity on scan 3 reduces the amount of radial velocity aliasing. This eliminates one radial velocity that may be aliased from scan 2 or 3, from being copied to the fully conditioned radial velocity field.
Reinitializing the wind field model every volume scan better represents a quickly changing wind field. An accurate wind field model is important because the wind field model is used as a dealiasing reference in data sparse regions.
These changes will improve the gust front detection performance, which enhances aviation safety
The 8th Conference on Aviation, Range, and Aerospace Meteorology