Improving precipitation estimates from dual-wavelength radars

Dual-wavelength radars can, in principle, provide extra information to help in the estimation of precipitation. One method would be to use the differential attenuation measured between the two frequencies of the radar as an indication of the rain rate. Microwave attenuation is widely regarded as a good estimator of the intensity of precipitation. The theory of microwave attenuation is presented, as well as an estimation of the error sources involved in the measurement of attenuation with dual-wavelength radars. Two long-time datasets of disdrometer data are used to test the feasibility of tuning the radar Z - R relationship by measuring the relation between reflectivity and X-band attenuation. As an interesting fact, a surprising proportionality between these two variables is found for higher intensities of precipitation (Z > 40 dBZ). This finding limits the capabilities of dual-wavelength radars to use attenuation as a second parameter, since at higher reflectivities X-band attenuation is almost equivalent to reflectivity