Light Scattering Problem and its Application in Atmospheric Science

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2011-02-22

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The light scattering problem and its application in atmospheric science is studied in this thesis. In the first part of this thesis, light scattering theory of single irregular particles is investigated. We first introduce the basic concepts of the light scattering problem. T-matrix ansatz, as well as the null-field technique, are introduced in the following sections. Three geometries, including sphere, cylinder and hexagonal column, are defined subsequently. Corresponding light scattering properties (i.e., T-matrix and Mueller Matrix) of those models with arbitrary sizes are simulated via the T-matrix method. In order to improve the efficiency for the algorithms of single-light scattering, we present a user-friendly database software package of the single-scattering properties of individual dust-like aerosol particles. The second part of this thesis describes this database in detail. Its application to radiative transfer calculations in a spectral region from ultraviolet (UV) to far-infrared (far-IR) is introduced as well. To expand the degree of morphological freedom of the commonly used spheroidal and spherical models, triaxial ellipsoids were assumed to be the overall shape of dust-like aerosol particles. The software package allows for the derivation of the bulk optical properties for a given distribution of particle microphysical parameters (i.e., refractive index, size parameter and two aspect ratios). The array-oriented single-scattering property data sets are stored in the NetCDF format. The third part of this thesis examines the applicability of the tri-axial ellipsoidal dust model. In this part, the newly built database is equipped in the study. The precomputed optical properties of tri-axial models are imported to a polarized addingdoubling radiative transfer (RT) model. The radiative transfer property of a well-defined atmosphere layer is consequently simulated. Furthermore, several trial retrieval procedures are taken based on a combination of intensity and polarization in the results of RT simulation. The retrieval results show a high precision and indicate a further application in realistic studies.

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