Attenuation Correction in Dual-Wavelength Analyses

Abstract

In using a dual-wavelength radar system to detect hail, erroneous positive hail signals can result because of the stronger attenuation of the shorter wavelength radar beam. We present a simple technique to correct for attenuation in dual-wavelength analyses. The technique makes use of an attenuation-reflectivity relationship of the form, A = CZxp, where Zx is the S-band reflectivity, C is a coefficient which is determined on a ray-by-ray basis, and p is the exponent, which is assumed to be a constant. In situations where rays of radar data contain a mixture of rain and hail, the attenuation-correction scheme can erroneously apportion more of the attenuation to hail regions rather than to rain regions. The scheme is modified to account for such situations.