Attenuation of the electromagnetic waves due to moist and wet snow

Abstract

Using oblate spheroidal representation for snowflakes, the attenuation of the electromagnetic waves due to moist and wet snow is computed. The results are obtained for two orthogonal polarizations of the incident wave in the forward-scattering direction. The computations are made for microwave frequencies between 6 and 100 GHz, and also for precipitation rates between 0.5 and 3 mm/hr. It is found that the attenuation of both polarizations for both types increases with increasing frequency at a fixed value of the precipitation rate. In addition, the attenuation of wet snow is greater than the attenuation of moist snow over a range of frequency values. At a fixed frequency, the attenuation of both polarizations for both types of snow is also observed to increase with increasing precipitation rate. In this case, the attenuation of wet snow is also found to be greater than the attenuation of moist snow over a range of precipitation values. This is due to the fact that the attenuation is affected by the imaginary part of the index of refraction which is found to increase with increasing frequency and wetness of snow. The difference between the attenuation of both types and the differential attenuation of both types are observed to follow the same trend as the attenuation over the same range of frequency values and precipitation rates.