The recent development of satellite observations of limb scattered sunlight at optical wavelengths has afforded a new opportunity to measure the vertical structure of atmospheric composition from the upper troposphere to the mesosphere, on a global scale. The determination of profiles of atmospheric composition from observed limb radiance profiles requires two elements, a forward radiative transfer model and a species specific inversion algorithm. In this work, the development of a new, fully spherical, successive orders radiative transfer model, SASKTRAN, for the analysis of limb scattered sunlight is presented. The model is incorporated into a novel relaxation algorithm that employs spectral ratios to retrieve profiles of stratospheric aerosols from limb radiance measurements collected by the Canadian OSIRIS instrument on the Odin satellite.<p>The SASKTRAN forward model results compare favorably with both OSIRIS observations as well as with other radiative transfer model calculations while remaining computationally practical for the operational inversion of large satellite data sets.<p>The spectral ratio relaxation algorithm is able to retrieve aerosol number density profiles at stratospheric altitudes from limb radiance profiles assuming the height profile of the aerosol particle size distribution is known. The equivalent aerosol extinction derived from the OSIRIS measurements at visible wavelengths agrees with coincident occultation measurements from other satellite instrumentation to within 15% when a size distribution appropriate for background aerosol conditions is used. Finally, it is demonstrated that the incorporation of simultaneous infra-red observations at 1530 nm into the inversion yields a useful proxy for the aerosol size distribution parameters.

In the first part of this dissertation, radiative interactions with single irregular particles are simulated. We first introduce the basic method and techniques of Finite- Difference Time-Domain method(FDTD), which is a powerful method to numerically solve Maxwell's equations with high accuracy. To improve the efficiency of FDTD, we also develop a parallel FDTD code. Since FDTD can simulate light scattering by arbitrary shape and compositions, we study several radiative interaction cases for single particles in an external plane parallel light source: the surface roughness effects on the scattering, electric and magnetic energy density distribution in irregular particles, and backscattered Mueller images. We also develop an innovative and accurate method to simulate the infinitesimal electric dipole radiation from inside a particle with arbitrary shape and composition. Our research and results are very important to study light scattering by irregular particles, Raman scattering and fluorescence. In the second part of the dissertation, we study radiative interactions in an atmosphere-ocean system. By using the so called Matrix operator method, not only the radiance of the radiation field, but also the polarization of the radiation field are obtained. Given the single layer information for the atmosphere, time dependent ocean surface shapes, and the ocean with no interface, the Matrix operator method couples these three layers and provides both the radiance and polarization reaching a certain detector in the time domain, which are essential for atmospheric science and oceanography. Several simple cases are studied by this method to demonstrate its accuracy and robustness. We also show the most difficulties in this method and discuss what one need to do in future research works.

No description available.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 85-87). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1968. / Typescript. Vita. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

No description available.

This thesis is a study of the solutions of the equations of radiative transfer by an invariant imbedding approach.

We describe the implementation and testing of the TREVR (Tree-based REVerse Ray-tracing) radiative transfer algorithm in the ChaNGa (Charm N-body Gravity solver) code. We calculated the optimal values for the source walk opening angle and ray trace walk refinement parameter of θ = 0.5 and τ = 0.01 respectively. We then studied the effects of the merging of sources on the accuracy of the calculated flux in absorbing regions, noting a systematic negative error and an angular dependence across all optical depths. We dubbed this the “Complex Sources Problem” and provide suggestions to mitigate its effects / Thesis / Master of Science (MSc)

It has been shown that the energy exchange between two objects can be greatly enhanced when the separation between the objects is on the order of the wavelength of thermal emission. The earliest theoretical and computational work focused on simple planar and spherical geometries, or they resorted to approximations that separated the object to outside of the thermal wavelength \(\lambda_T = hc/(k_BT)\). Since those original works, the study of near-field energy exchange has expanded to object shapes that can be described by a separable coordinate system using a spectral expansion of the dyadic Green function of the system. The boundary element method has also been used to study arbitrary shapes in thermal equilibrium. Application of these new expansion methods to general shapes out of thermal equilibrium will facilitate in the optimization of nanoscale structures. A three step process is used to investigate the effects of object shape on the total and directionality of the energy exchange between objects. First, a general expression for the energy flux between the objects will be formulated. Second, a computational method to evaluate the expression will be implemented. Finally, the effects of varying the surface geometry will be explored. The computational results demonstrate that the total energy exchange between two bodies is influenced by the surface shape of the objects even when the surface areas are held constant. While the primary increase over the classical blackbody energy exchange \(\sigma T^4 A\) is primarily governed by separation of the surfaces, we show that the view factors from classical far-field radiative transfer can be used to predict the change in the total energy exchange from a reference configuration at the same separation when the surface area of the two objects is comparable. Additionally, we demonstrate that the spatial distribution of the energy exchange can be localized into small spatial region with a peak value increased over \SI{30}{\percent} by using two objects with dramatically different projected areas.