Dual-wavelength hail detection with NEXRAD radars

The feasibility of detecting hail by dual-wavelength-ratio radar measurements with the proposed single-transmitter dual-wavelength NEXRAD radars is investigated theoretically, applying the Mie-theory analysis of Tuttle and Rinehart (1983). Simulated radar signals for spherical monodisperse hail of diameter 0.5-10 cm with water coatings from zero to 1 mm thick and for transmitter wavelengths 10.83 and 10.60 or 11.1 and 10.34 cm are presented graphically and discussed. It is found that water-coating thicknesses are difficult to distinguish, but that hail larger than 1.5 cm (for the 10.83-10.60-cm wavelength pair) or 1.3-1.7 cm (for 11.1-10.34 cm) should be detectable at dual-wavelength signal strengths of a few tenths of a dB.