激光在准球形边界卷云中传输的衰减和透过特性

doi:10.3964/j.issn.1000-0593(2022)01-0316-06

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Abstract An altitude cirrus cloud is mostly composed of ice particles, which affects laser signal transmission over ground to air links. Basing on, the distribution and scattering characteristics of ice crystal particles in high altitude cirrus cloud sand by cirrus clouds considering the spherical curvature of the Earth and multiple scattering, the laser transmission and attenuation characteristics of spherical boundary clouds, are studied in this paper using the spherical model of the discrete ordinate method (CDISORT). The laser transmittance differences between the plane-parallel model and the quasi-spherical model in the ice cloud atmosphere under different solar zenith angles are compared. The laser signal propagation’s attenuation and transmittance characteristics are compared through cirrus clouds at three wavelengths（0.65, 1.06, 3.8 μm）are calculated numerically. The results show that when the solar zenith angle is small, the relative error of the laser transmittance between the two models is very small when the solar zenith angle is less than 80°, the relative error between the two models at the laser wavelength of 0.65 μm is only 1.72% when the radiation transfer equation of the spherical atmosphere is calculated according to the plane-parallel atmosphere model, however, when the solar zenith angle is greater than 80°, the relative error of the laser transmittance between the two models in the ice cloud atmosphere increases, the relative error between the two models at the laser wavelength of 0.65 μm is 69%; The laser attenuation caused by propagation through the clouds is related to the effective radius, transmission distance, and laser wavelength when a single scattering of a cirrus cloud is considered, as the optical thickness increases and the laser transmittance’s change with the cloud layer decreases, the maximum transmittance is achieved at the laser wavelength of 1.06 μm and the minimum transmittance is achieved at the laser wavelength of 3.8 μm; The laser transmittance at the wavelengths of 0.65 and 1.06 μm increases with the effective radius of cloud particles, but at the wavelength of 3.8 μm, it does not increase under the same constraints, the laser transmittance of cloud decreases with the increase of relative azimuth, and different cirrus dispersion models have different effects on the laser transmittance. The results of the characteristics of laser transmission through cirrus clouds presented in this works provide an important theoretical basis for engineering applications, including ground-to-air link satellite-borne, airborne laser communication, laser radar detection, at the same time, it can lay a research foundation for the application of laser remote sensing, guidance and early warning of ground to air link.

Key words：Laser radiation transmission; Cirrus clouds; Cloud transmittance; Multiple scattering

Received: 2020-12-11 Accepted: 2021-04-08

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Corresponding Authors: GAO Ming E-mail: minggao1964xatu@163.com

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2022)01-0316-06 OR https://www.gpxygpfx.com/EN/Y2022/V42/I01/316