Currently, the effect of the vertical resolution on the brightness temperature (BT) has not been examined in depth. The uncertainty of the freezing level (FL) retrieved using two different satellites' data is large. Various radiative transfer (RT) codes yield different BTs in strong scattering conditions. The purposes of this research were: 1) to understand the uncertainty of the BT contributed by the vertical resolution numerically and analytically; 2) to reduce the uncertainty of the FL retrieval using new thermodynamic observations; and 3) to investigate the characteristics of four different RT codes. Firstly, a plane-parallel RT Model (RTM) of n layers in light rainfall was used for the analytical and computational derivation of the vertical resolution effect on the BT. Secondly, a new temperature profile based on observations was absorbed in the Texas A&M University (TAMU) algorithm. The Precipitation Radar (PR) and Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) data were utilized for the improved FL retrieval. Thirdly, the TAMU, Eddington approximation (EDD), Discrete Ordinate, and backward Monte Carlo codes were compared under various view angles, rain rates, FLs, frequencies, and surface properties. The uncertainty of the BT decreased as the number of layers increased. The uncertainty was due to the optical thickness rather than due to relative humidity, pressure distribution, water vapor, and temperature profile. The mean TMI FL showed a good agreement with mean bright band height. A new temperature profile reduced the uncertainty of the TMI FL by about 10%. The differences of the BTs among the four different RT codes were within 1 K at the current sensor view angle over the entire dynamic rain rate range of 10-37 GHz. The differences between the TAMU and EDD solutions were less than 0.5 K for the specular surface. In conclusion, this research suggested the vertical resolution should be considered as a parameter in the forward model. A new temperature profile improved the TMI FL in the tropics, but the uncertainty still exists with low FL. Generally, the four RT codes agreed with each other, except at nadir, near limb or in heavy rainfall. The TAMU and the EDD codes had better agreement than other RT codes.

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.

Laser-Induced Breakdown spectroscopy (LIBS) and Laser-Induced Thermal Emission (LITE) emission based laser remote sensing were investigated with the application to the remote measurements of trace chemical species. In particular, UVvisible LIBS and Mid-IR LITE systems were developed and measurements of remote targets and chemical surfaces were studied. The propagation through the atmosphere of the multi-wavelength backscattered LIBS and LITE optical spectrum with atmospheric absorption effects on the returned lidar signal was investigated. An enhanced model of the atmospheric effects on emission-based laser-remote sensing was developed and found to be consistent and in agreement with our experimental results. LITE measurements were performed which involved heating a remote hard target and recording the vibrational band emission spectra produced. Sample heating was carried out using a 1.5W cw-CO2 10.6 μm wavelength laser, and a 9W cw-diode laser operating at 809nm. The emission spectra over the wavelength range of 8 to 14 μm was observed which can be potentially used to detect and identify chemical composition of the target. LITE spectra of DMMP and DIMP (chemical agent simulants), paints, and energetic materials on various substrates were measured for the first time. A LIBS study was carried out with a 1.064 μm Nd:YAG laser (10 ns pulses, 50mJ per pulse) and remote LIBS measurements were performed for aluminum, copper, steel and plastics over the spectral range of 200 – 1000nm. LIBS measurements as a function of range were studied, and compared to a modified lidar equation suitable for emission based lidar remote sensing. A computer simulation model was developed for emission-based LIDAR remote sensing such as LIBS and LITE. This involved the development and modification of atmospheric transmission modeling programs which use the HITRAN, PNNL and other atmospheric spectral databases to model the transmission of the atmosphere over a wide range of wavelengths from the deep-UV near 200 nm to the mid-IR near 14 microns. A comparison of HITRAN simulations with the PNNL database calculated spectra was carried out and used for the first time for improvements of the HITRAN database line intensities. In addition, a Principal Component Analysis (PCA) of the LIBS and LITE lidar return signal as a function of range was performed. This PCA analysis showed, for the first time, the degradation of the chemical selectivity (i.e. identification capability) of the emission lidar system as the range was increased and the effect of atmospheric absorption spectral lines on the propagated LIBS and LITE lidar multi-wavelength spectral signal.

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Three aspects of the Habitability of the Northern Plains of Mars to organics and terrestrial-like microbial life were assessed. (1) Protection offered by small surface features and (2) the breakdown of rocks to form soils were examined using a radiative transfer computer model. Two separate sublimation experiments provided a basis to improve (3) estimates of the amount of available water today and in the past by determining the fractionation of HDO between present-day reservoirs.(1) UV radiation sterilizes the hardiest of terrestrial organisms within minutes on the Martian surface. Small surface features including pits, trenches, flat faces and overhangs may create "safe havens" for organisms by blocking much of the UV flux. In the most favorable cases, this flux is sufficiently reduced such that organic in-fall could accumulate beneath overhanging surfaces and in pits and cracks while terrestrial microorganisms could persist for several tens of martian years.(2) The production of soils on the surface is considered by analogy with the arid US Southwest. Here differential insolation of incipient cracks of random orientations predicts crack orientation distributions consistent with field observations by assuming that only crack orientations which shield their interiors, minimizing their water loss, can grow, eventually disrupting the clast.(3) Disaggregated water ice to simulate the polar caps was produced by flash freezing in liquid nitrogen and crushing. When dust was added to the mixtures, the D/H ratio of the sublimate gas was seen to decrease with time from the bulk ratio. The more dust was added to the mixture, the more pronounced was this effect. The largest fractionation factor observed during these experiments was 2.5. Clean ice was also prepared and overlain by dust to simulate ground ice. Here, the movement of water vapor was modeled using an effective diffusivity that incorporated both adsorption on grains and diffusion. For low temperatures (<-55°C) a significant difference between the diffusivities of H2O and HDO was observed. This suggests adsorptive-control within the regolith as energies of interaction are 60-70kJmol-1. This ability of the martian regolith to preferentially adsorb HDO decouples the ice table and polar caps from the atmosphere and allows for geographic variations in the D/H ratio on Mars.

Thesis (Ph. D.)--University of Washington, 1989. / Vita. Includes bibliographical references (leaves [118]-122).

Thesis (Ph.D.(Metallurgical Engineering))--University of Pretoria, 2007. / Summaries in Afrikaans and English. Includes bibliographical references.

Mémoire (M.Sc.A.)--Université du Québec à Chicoutimi, 1991. / Document électronique également accessible en format PDF. CaQCU

Thesis (M.S.)--Florida State University, 2004. / Advisor: Dr. Xiaolei Zou, Florida State University, College of Arts and Sciences, Dept. of Meteorology. Title and description from dissertation home page (viewed Jan. 12, 2005). Includes bibliographical references.