Progress report on analysis of differential attenuation radar data obtained during WISP-91

Liquid water attenuates radar signals more strongly at shorter wavelengths that at longer ones. In theory, the differential attenuation at two wavelengths offers a new method for obtaining range resolved measurements of cloud liquid water content by remote sensing. A relatively inexpensive dual wavelength system was assembled from existing X band (3.2 cm) and K(a)-band (0.87 cm) radars and operated during the 1991 Winter Icing and Storms Project to experimentally test this technique. Analysis of the data is in early stages. The differential attenuation theory is described, along with experimental procedures and instrumentation, data collection, data processing, and one preliminary case study. The detailed case study of a cloud that produced very light drizzle prompted development of automated editing refinements to the original processing algorithm to remove complications from ground clutter, non-Rayleigh scattering, receiver saturation, and other factors. The overall study had potential applications to aircraft icing (safety).