Multi-frequency radar observations of the melting layer

A multi-frequency radar that combines millimeter-wave (MMW) and microwave signals provides additional hydrometeor microphysical information that is not available from a single frequency system. The additional information is contained in the Mie scattering and signal extinction experienced by the MMW signal. These effects can be quantified by comparing MMW data, with measurements simultaneously collected at a second, usually lower, frequency. This technique has been used previously to estimate particle size distributions in rain and in deep ice clouds. Unfortunately, entire precipitating cloud columns cannot yet be characterized using these methods because scattering and extinction from melting particles is not well understood at millimeter-wave frequencies.