Study of an Automated Doppler Radar Velocity Dealiasing Scheme

An automated Doppler radar velocity dealiasing scheme is developed. The velocity dealiasing algorithm is based on the horizontal and vertical continuity of velocity fields. The algorithm first determines a set of initial reference radials and gates by finding the weakest wind region, where, the constraint of orientation continuity between adjacent elevation initial reference radials is used. Then from these initial reference radials and gates, the algorithm checks continuities among adjacent gates and corrects for the velocity values with large differences that are larger than given threshold. After the dealiasing process using the first set of initial reference radials, the algorithm checks if there are strong wind shears in velocity field. If strong wind shears exist, the algorithm second determines a set of initial reference radials and gates by finding the weak wind shear radial with the most nonmissing velocity gates, then the dealiasing procedures are repeated one time. A multipass dealiasing procedure is employed in the algorithm that use very strict criteria in earlier passes and relaxed criteria in later passes to ensure a good reference for dealiasing in the later passes. The dealiasing algorithm is tested and evaluated across more than 1000 volume scans of S-band Doppler weather radar encompassing events of tornadoes, squall lines, isolated strong storms, and typhoons with first and second velocity ambiguity. The results show that the algorithm is very robust, it can correct for aliased Doppler velocity data properly in more than 99.5%.