Parameterization of basic optical radiation scattering properties of ice crystal particles

Alexander G. Petrushin

doi:10.1117/12.617512

17 March 2005 Parameterization of basic optical radiation scattering properties of ice crystal particles

Alexander G. Petrushin

Proceedings Volume 5829, 13th International Workshop on Lidar Multiple Scattering Experiments; (2005) https://doi.org/10.1117/12.617512
Event: 13th International Workshop on Lidar Multiple Scattering Experiments, 2004, St. Petersburg, Russian Federation

Abstract

With the use of the expressions obtained by us earlier the extinction efficiency K_ex, absorption efficiency K_a, single scattering albedo A and phase scattering function P(θ)/4π for optical radiation of a crystalline cloud medium were calculated. The optical characteristics mentioned are necessary for calculation of crystalline and mixed-phase clouds radiation properties used in different climate models. The crystalline cloud microstructure model included the ice hexagonal plates and columns cna be arbitrarily oriented in space. Two possible cases of ice crystal orientation in space were considered -- a chaotic orientation and an arbitrary orientation of the prisms main axis and the plates maximum surfaces in the horizontal plane. The hexagonal prism shape factor is c = 2a/l (where 2a is prism diameter and l is its length), 0.05 ≤ c ≤ 10.0. Theoretically estimated values of K_ex for a crystalline medium microstructure were compared with the experimental values K_ex obtained at the IEM. For execution of K_e calculations by hexagonal prisms with a chaotic orientation in space which sizes are comparable with wavelength of incident radiation can be used Mie-Lorentz theory for spherical particles with the same refractive index and effective radius R₃₂. The absorption efficiency K_a by hexagonal prisms with different orientation in space can be calculated using with the suggested expressions for K_a in view effective size R₃₂. For small (diffraction) scattering angles the phase scattering function P(θ)/4π for ice crystals which sizes are more than wavelength with the high precision may be described by the phase scattering function P(θ)/4π for spherical particles with the effective radius R₂ the same as the effective size R₂ for ice crystals.

Citation Download Citation

Alexander G. Petrushin "Parameterization of basic optical radiation scattering properties of ice crystal particles", Proc. SPIE 5829, 13th International Workshop on Lidar Multiple Scattering Experiments, (17 March 2005); https://doi.org/10.1117/12.617512

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