Hail Detection with Polarimetric Radar

Dual-polarization radars typically transmit horizontally and vertically polarized waves and receive polarized backscattered signals. Because illuminated hydrometeors are not spherical, their radar backscatter cross sections are not the same for the two polarizations. Hydrometeor size, shape, orientation, and thermodynamic phase can be inferred from returned signals. Polarimetric hail algorithms exploit properties of returned signals, seeking departures from the “rain-only” case. Hail location can be precisely specified. Importantly, the suite of measurements provides redundancy that can be useful for eliminating false alarms and identifying marginal events. Here the more promising proposed detection techniques are reviewed, applied to a severe hail event, and evaluated for operational use.