The effect of precipitation rate on the phase shift of the electromagnetic wave due to various types of snow

Using oblate spheroidal representation for snowflakes, the phase shift of the electromagnetic waves due to dry, moist, wet, and watery is computed. The results are obtained for two orthogonal polarizations of the incident wave in the forward-scattering direction. The computations are made for various microwave frequencies between 6 and 100 GHZ, and also for precipitation rates between 0.5 and 3 mm/hr. The effect of the precipitation rate, R, on the phase shift for all types of snow is examined. It is found that at a fixed R, the phase shift of both polarizations for each type of snow increases with increasing frequency up to a value, Fmax, beyond which the phase shift decreases with increasing frequency. The value of Fmax is different for each type of snow and it increases with increasing wetness of snow. In addition, it is observed that the values of phase shift of wet and watery snow are very close. It is also observed that at a fixed frequency, greater than Fmax, the phase shift for both polarizations decreases with increasing R for each type of snow. In addition, it is found that the phase shift of both polarizations of snow decreases with snow wetness for fixed precipitation rate and frequency. The differential phase shift of all types of snow is also observed to follow the same trend as the phase shift over the same frequency range and precipitation rates.