Attenuation correction in dual-wavelength analyses

It is pointed out that erroneous positive hail signals can be produced by dual-wavelength radar systems for detecting hail owing to the stronger attenuation of the shorter wavelength radar beam. A simple technique is presented here for correcting for attenuation in dual-wavelength analyses. The technique makes use of an equation that gives the attenuation in terms of the S-band reflectivity. In situations where rays of radar data contain a mixture of rain and hail, however, the attenuation-correction scheme outlined here can erroneously assign more of the attenuation to hail regions than to rain regions. The scheme is therefore modified so as to account for such situations. The scheme is easy to use and entails relatively little extra computing time (20 percent) in the dual-wavelength processing.