Velocity track display - a technique to extract real-time tropical cyclone circulations using a single airborne Doppler radar

The VTD algorithm is a harmonic analysis method similar to the velocity-azimuth display technique for ground-based radars; however, it is designed to deduce the primary circulation properties of atmospheric vortices such as tropical cyclones. When an aircraft, equipped with a Doppler radar scanning in a track-orthogonal plane, penetrates a cyclonic circulation, VTD decomposes Doppler velocities on cylindrical rings into tangential, radial, and the mean cross-track component of the wind velocity. Obtaining estimates of the vortex circulation requires data from only one aircraft flight leg instead of two in the pseudodual Doppler radar method. A version of VTD was run successfully on board a NOAA WP-3D during the 1991 hurricane season. -from Authors