Study on the Scattering Characteristics of Ka Millimeter Wave by Dust Storms

Abstract As to study the scattering characteristics of millimeter wave by sand particles, the integrated detection on dust storms over the Taklimakan Desert was the first time to conduct with the Ka band millimeter wave radar, the Grimm 180, the Laser Particle Size Analyzer and the visibility meter. The complex permittivity of sand particle (em), the probability distribution function of sand particles, the number of sand particles, the attenuation coefficient and the reflectivity factors were calculated by the observations of these instruments; moreover, the power spectrums of the dust storm, sunny day and precipitation were comparatively analyzed. The results showed that: the em of 35 GHz millimeter wave by sand particles is 3.0078-j0.0987. The probability distribution of sand particles conforms to lognormal distribution, with the mean of -2.352 and the standard deviation of 0.422. Furthermore, when the visibility drops from 3000 m to 0 m, the number of sand particles rises from 2  × 105 to 1  × 106 in L • min−1 and the attenuation coefficient increases from 1 to 8 dB • km−1. The peak and the average values of power spectrums in dust storm are lower than those in precipitation, which indicates that the scattering ability of sand particles is less than that of precipitation particles. During the dust storms, the reflectivity factors range between -40 dBZ and 20 dBZ. These findings provide theoretical basis for the further study of the scattering properties of sand particles in the future.