Comparison between the Phase Shifts of the Electromagnetic Waves due to Moist Snow and Wet Snow

Based on the point matching technique, the phase shift of the electromagnetic waves due to two types of snow is computed. The analysis is restricted to the forward-scattering direction from oblate spheroidal moist and dry snow. Numerical results are obtained for two orthogonal polarizations of the incident wave. The calculations are made for various microwave frequencies, between 6 and 100 GHz, and also for different precipitation rates, between 0.5 and 3 mm/hr. The effect of the frequency and the precipitation rate on the phase shift for both types of snow is examined. It is found that at a fixed value of the precipitation rate, the phase shift of both polarizations for both types of snow increases with increasing frequency up to a value, f_max , beyond which the phase shift decreases with increasing frequency. The phase shift of moist snow is always greater than the phase shift of wet snow. It is also observed that at a fixed frequency, less than f_max, the phase shift of both polarizations for both types of snow increases with increasing precipitation rate and the phase shift of moist snow is greater than the phase shift of wet snow. The differential phase shift of both types is also observed to follow the same trend as the phase shift over the same frequency range and precipitation rates