Light Backscattering by Horizontally Oriented Ice “Plate,” “Column,” and “Hollow Column” Particles of Cirrus Clouds

Abstract

Cirrus clouds play an important part in the formation of our planet’s climate due to their influence on its radiation balance. Their study requires solving the problem of interpreting atmospheric laser sounding data, which is implemented differently for clouds consisting of randomly oriented ice crystals and clouds containing layers of horizontally oriented crystals. In this paper, within the framework of the physical optics method, properties of light backscattering by horizontally oriented cirrus cloud ice particles of the “plate,” “column,” and “hollow column” types are numerically simulated. The simulations are carried out for particles ranging in size from 10 to 316 µm for wavelengths of 0.532 and 1.064 μm; the complex refractive index of ice is 1.3116 + i1.48 × 10⁻⁹ and 1.3004 + i1.9 × 10⁻⁶, respectively. The solution is obtained for typical lidar tilt angles of 0°, 0.3°, 3°, and 5°. The results are of interest for developing an optical model of cirrus clouds in problems of interpreting atmospheric laser sounding data in the presence of clouds containing ice crystals of the abovementioned shapes.