An improved automated velocity dealiasing algorithm for Doppler weather radar

To improve velocity dealiasing performance in strong wind shear zones and distant isolated echo regions as well as to mitigate the impact of velocity noise, an improved velocity dealiasing algorithm has been developed. The key enhancements are as follows. (1) To improve the performance under intense horizontal wind shear, steps utilizing horizontal neighborhood dealiasing and a radial-then-tangential sequence are inserted between the first and second rounds of full-azimuth radial dealiasing (which employs a tangential-then-radial sequence in the original algorithm). (2) For distant isolated echo regions, vertical neighborhood dealiasing is added following horizontal neighborhood dealiasing. (3) A noise filtering process is implemented after all dealiasing steps to mitigate the impact of noise on the identification of small-scale convergence, divergence, and vortex features. The velocity dealiasing performances of both the original and the improved algorithms are analyzed based on four severe weather cases. The improved algorithm is further tested and evaluated using 3519 volume scans of tornadoes, squall lines, isolated severe storms, and typhoons observed by S-band Doppler weather radars. The results indicate that the improved algorithm effectively resolves velocity aliasing in strong wind shear zones and distant isolated echo regions—both challenging scenarios for the original algorithm—and significantly mitigates velocity noise artifacts. The dealiasing accuracy nearly approaches 100%, with residual aliasing or improper corrections occurring only under clutter-contaminated conditions or in small, isolated echoes at long ranges. The enhanced algorithm demonstrates superior performance compared to the original method, robustly handling various velocity aliasing and noise interference.