Influence of Raindrop-Size Distribution on the Differential Reflectivity up to Submillimeter Wavelength of 0.96 mm

The rain attenuation was calculated by using the Marshall and Palmer, the gamma and the Weibull raindrop-size distributions. The microwave experimental measurement data from 8.4 GHz (3.75 mm) to 312.5 GHz (0.96 mm) were compared with our calculations. The Weibull distribution has the best agreement with the measurements, especially above 100 GHz. The differential reflectivity Z_DR was also calculated using these three distributions. To this end, we used the horizontal and vertical radar cross sections which were computed from Waterman's T-matrix method. It is shown that Z_DR greatly depends on raindrop-size distributions and has potential for determing drop-size distributions with high accuracy.