Dual-polarization radars typically transmit horizontally and vertically polarized electromagnetic waves and receive polarized backscattered signals. Because illuminated hydrometeors are not exactly spherical, their radar backscatter cross-sections are not the same for the different polarizations. The propagating waves are subject to scattering, differential attenuation, differential phase shifts, and depolarization. Signal properties change continuously as the waves propagate yielding information that can be used to estimate particle size, shape, orientation, and thermodynamic phase.

Polarization measurements obtained with NCAR s S-band, dual-polarization radar during a number of field programs will be used to describe efforts to detect rain-snow boundaries, designate freezing levels, and quantify winter precipitation. Results have import for the detection of icing hazards and airport deicing activities.