Study On Light Scattering And Radiative Transfer Properties Of Water Clouds And Ice Clouds

Clouds composed of liquid water droplets or ice cry stals suspended in the air are important components of the atmosphere.Clouds are one of the discrete random mediums,and the study of light scattering and radiative transfer properties involving clouds is of great significance to atmospheric detection,satellite remote sensing,space optical communication and so on.Light scattering and radiative transfer properties of water clouds and ice clouds were studied in this thesis.The main works included;1.The light scattering properties of single spherical liquid water droplet and non-spherical ice crystal were obtained by Mie theory,anomalous diffraction theory,geometric optics method,respectively.Considering liquid water content(LWC)and ice water content(IWC)respectively,combining the light scattering properties of individual cloud particle with gamma distribution model,average single scattering properties of water clouds and ice clouds were calculated numericallu.2.On the foundation of the first part,based on the latest C-code version of DISORT(CDISORT),water clouds and ice clouds transmittance changed with optical thickness,effective radius,LWC/IWC,surface types and so on in plane-parallel atmosphere were simulated.And the differences of atmospheric transmittance under different water clouds and ice clouds scattering models were also compared.3.The differences between plane-parallel atmosphere and spherical atmosphere were analyzed.According to plane-parallel mode and pseudo-spherical mode of CDISORT,the differences of water clouds,ice clouds transmittance and reflectance between the two different atmospheric geometries at different solar zenith angles were compared.Considering spherical atmospheric geometry,water clouds and ice clouds reflectance changed with cloud microphysical properties,cloud scattering model,viewing zenith angle and relative azimuth angle were calculated numerically and analyzed at typical laser wavelengths(0.65?m,1.55?m)by using CDISORT with pseudo-spherical mode.The results show that water clouds and ice clouds transmittance increase first and then decrease with the increase of optical thickness or LWC/IWC.The effective radius of water clouds and ice clouds has different effects on atmospheric transmittance in different wavelength ranges.With the increase of solar zenith angle,the differences of water clouds and ice clouds transmittance and reflectance between the plane-parallel atmosphere and the spherical atmosphere also increase.Water clouds and ice clouds reflectance increase with the increase of optical thickness,but decrease with the increase of effective radius.In addition,the differences of water clouds,ice clouds reflectance and transmittance were great for different cloud scattering models,relative azimuth angle,incident wavelength and so on.