Dual polarization radars - Attenuation prediction

The paper reports the radar measurements of rain, using fast switching between vertically and horizontally polarized waves to determine the ratio of the reflectivities of raindrops at the two polarizations, and hence the oblateness and size of the drops. The measurements were made with a 10-cm radar on a 25-cm diameter antenna in southern England. They are compared with a theoretical statistical model of the scattering process. The results show that the cross correlation of pulse-to-pulse returns on vertical and horizontal polarizations is consistently high, and that the ratio may be determined with a standard error less than 0.2 dB. Preliminary results also show that the technique presented may be used to distinguish ice crystals from water drops.