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.

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.

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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.

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

The coldness of outer space is a huge thermodynamic resource that can be utilized as an infinite heat sink that helps in cooling terrestrial objects without the need for electrical energy through a phenomenon known as radiative sky cooling. In the last decade, radiative cooling has seen an increasing attention as a sustainable and clean cooling method and many researchers made smart use of it as a thermal management method. One example in the literature is the radiative cooling of solar cells. Like solar cells, Light Emitting Diodes (LEDs) are semiconductor devices that deteriorate because of high temperatures. Specifically, the high temperature in LEDs lowers their efficiency and lifetime. Therefore, reducing the temperature by increasing heat dissipation can help in optimizing the efficiency of the LED. In this work, I investigate a novel low-cost solution that can help in reducing the temperature of outdoor LEDs through radiative cooling. The suggested solution utilizes the coldness of outer space to radiatively cool the LED by using a layer of a visible-reflective-infrared-transparent material, nanoporous polyethylene (nanoPE), as a cover to reflect the visible light back to earth while transmitting infrared radiation to outer space. I theoretically discuss the potential cooling performance of LEDs in the suggested design and estimate a cooling power enhancement by 128 W/m2 in ideal conditions compared to current designs. In addition, I study the fabrication and characteristics of nanoPE and show how it can be used as a reflective/diffusive cover for LEDs. Lastly, I experimentally demonstrate the use of nanoPE as a cover for LEDs and show an LED temperature reduction of 15 ⁰C in the laboratory environment and 4 ⁰C outdoor and calculate a relative LED efficiency increase of 28% in the indoor scenario and 4% in the outdoor scenario. This efficiency increase can result in an energy saving of 2.2 TWh in the United States corresponding to at least 0.44 MMT CO2 emission reduction making this cooling solution attractive due to its low cost and high impact.