MeanK-RRelationships: Practical Results for Typical Weather Radar Wavelengths

Abstract
Total attenuation cross sections of raindrops derived from the Mie theory for wavelengths of 3.2, 5.6, and 10 cm and temperatures of −10°, 0°, 10°, and 20°C have been calculated and compared to the results of the Rayleigh approximation. The approximation gives (i) unacceptable systematic underestimation of total attenuation cross sections and (ii) a misrepresentation of the temperature influence for the shortest wavelengths. Experimental raindrop-size distributions (RSD) collected during the French “Cévennes 1986–88” hydrometeorological experiment were subsequently modeled using the classical negative exponential model and a three-parameter gamma model. The exponential model lies between widespread and thunderstorm RSD models proposed elsewhere in the literature, while the gamma model provides a better fit for experimental RSD data for the small diameters. Relationships between the attenuation K (dB km−1) and the rain rate R (mm h−1) are presented for the different wavelengths, temperatures, and ... Abstract Total attenuation cross sections of raindrops derived from the Mie theory for wavelengths of 3.2, 5.6, and 10 cm and temperatures of −10°, 0°, 10°, and 20°C have been calculated and compared to the results of the Rayleigh approximation. The approximation gives (i) unacceptable systematic underestimation of total attenuation cross sections and (ii) a misrepresentation of the temperature influence for the shortest wavelengths. Experimental raindrop-size distributions (RSD) collected during the French “Cévennes 1986–88” hydrometeorological experiment were subsequently modeled using the classical negative exponential model and a three-parameter gamma model. The exponential model lies between widespread and thunderstorm RSD models proposed elsewhere in the literature, while the gamma model provides a better fit for experimental RSD data for the small diameters. Relationships between the attenuation K (dB km−1) and the rain rate R (mm h−1) are presented for the different wavelengths, temperatures, and ...

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