Monopulse radar has been widely used in military application for tracking hard target such as airplanes. The angular location of the target can be determined with accuracy much finer than the radar beamwidth by processing the sum and difference of signals from spatially separated antennas. In this work, the monopulse processing is exploited for distributed targets of weather. As a result, angular distribution of radial velocities in both azimuth and elevation directions can be obtained at sub-beamwidth resolution, while a conventional weather radar cannot resolve them. This is especially important if the region of interest is located far from the radar such that the smoothing effect of radar volume is significant. For example, the tornado vortex signature (TVS), which is manifested by strong and localized azimuthal shears, deteriorates with increasing distance between the tornado vortex and the radar. The monopulse processing has the potential to enhance TVS to improve tornado detection at far ranges.

In this work, a sophisticated radar simulator is modified according to the configuration of the Phased Array Radar (PAR) at the National Weather Radar Testbed (NWRT) in Norman, Oklahoma. The SPY-1A antenna of the PAR was designed for monopulse tracking of hard targets. Preliminary results have shown that velocity distribution within a radar volume can be reconstructed in both azimuth and elevation directions using monopulse processing. This technique will be first demonstrated using numerical simulation. Moreover, a comprehensive statistical analysis will be conducted to assess and quantify the performance of the technique under various meteorological conditions.