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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Lagrangian methods for climatological analysis of regional atmospheric transport with an emphasis on Texas ozone exceedances

Dexheimer, Darielle Nicole 15 November 2004 (has links)
A quantitative climatology of atmospheric transport in Texas is developed using previously described Lagrangian trajectory methods (Rogers and Bowman, 2001; Bowman and Carrie, 2002). The trajectories are computed using winds from 1979-2001 from the National Center for Environmental Prediction (NCEP) Reanalysis Project data set. Probability distributions are created for particle transport using trajectories from urban areas, making six-hourly particle distributions available from four urban areas in Texas. These probability distributions represent a quantitative understanding of regional air transport. Time-dependent Green's functions are calculated given initial conditions such as urban areas weighted with respect to population. The Green's functions describe how air from urban areas is transported through the atmosphere as a function of time. Summertime backward Lagrangian trajectories initialized at 5 Texas Commission on Environmental Quality (TCEQ) monitoring stations are grouped according to the ozone value recorded at the station at the initialization time of the trajectory. The directions of the trajectories in each group are used to determine the relationship between the transport characteristics of the circulation over Texas and regional-scale observations of pollutants. Synoptic conditions occurring at the time of summertime ozone exceedances at the 5 TCEQ stations are investigated in order to resolve what conditions are likely to coincide with ozone exceedances.
82

Experimantal and theoretical studies of isoprene oxidation initiated by hydroxyl radical

Park, Ji Ho 17 February 2005 (has links)
Isoprene (2-methyl-1,3-butadiene) is the most abundant non-methane hydrocarbon mostly emitted from the trees and its oxidation by hydroxyl radical contributes significantly to the tropospheric ozone production. We investigate the development of a detailed predictive mechanism for isoprene oxidation using both theory and experiment. We have identified a novel cyclization pathway for the radicals formed by hydroxy radical (OH) addition to the inner carbons of isoprene. The pathway predicted that C5 carbonyl compounds are produced, and it may also provide information on the preference of sites for OH addition. The nitrite/nitrate isomerization is directly related to the competition between ozone production and radical termination and was investigated using variational RRKM theory coupled with the master equation. We find that the dominant fate of the β-hydroxy alkoxy radicals produced from the dissociation reaction of nitrite is a prompt dissociation, whereas δ-hydroxy radicals isomerize to form dihydroxy radicals. We have performed experiments using laser photolysis (LP)/ laserinduced fluorescence (LIF) spectroscopy to study the initial addition reaction of the hydroxyl radical to isoprene. The overall reaction rates were estimated from experiments conducted at various pressures and temperatures. The determined Arrhenius rates are k∞(T) = (3.49±0.46)x10-11exp(366±40)/T molecule-1 cm3 s-1 and k∞(T) = (3.58±0.18)x10- 11exp(356±18)/T molecule-1 cm3 s-1, for the OH and OD addition reactions, respectively. Isoprene oxidation in the presence of O2 and NO was studied and, based on simulations to OH cycling curves, we determined a value of (9.0±3.0)x10-12 molecule-1 cm3 s-1 for the overall reaction rate constant of hydroxy peroxy radical with NO at 298 K. We report a rate constant for O2 addition to the hydroxy alkyl radical of (2.3±2.0)x10-12 molecule-1 cm3 s-1 at 298 K. We find little generation of OH from the OD initiated oxidation of isoprene, and no significant differences in OH and OD cycling, which suggests that the H-shift isomerization is the major pathway for δ-hydroxy alkoxy radicals in agreement with theoretical predictions.
83

Analyse par modélisation tridimentionnelle des processus physico-chimiques déterminant la production d'ozone

Lasry, Fanny Bergametti, Gilles. Coll, Isabelle. January 2006 (has links) (PDF)
Thèse de doctorat : Chimie de la pollution atmosphérique et physique de l'environnement : Paris 12 : 2006. / Titre provenant de l'écran-titre. Bibliogr. : 188 réf.
84

Direct sensitivity analysis in air quality models

Hakami, Amir, January 2003 (has links) (PDF)
Thesis (Ph. D.)--School of Civil and Environmental Engineering, Georgia Institute of Technology, 2004. Directed by Armistead Russell. / Vita. Includes bibliographical references (leaves 216-220).
85

Electrochemical generation of green oxidants

Zhou, Haihui., 周海辉. January 2010 (has links)
published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy
86

Environmental impact of green house gases on Nigeria

Douglas, Boma January 2000 (has links)
An analysis of climate change in Nigeria has been carried out. The aim was to investigate the environmental impact of Green house gases. The three zones of the country namely the extreme North, the middle zone and the extreme South have all been separately examined with respect to changes in solar radiation, temperature, precipitation and evaporation. The agricultural productivity for each zone was compiled, and trend plots over time carried out. Correlation tests were done between productivity and climatic changes and it was found that each zonal area reacted differently to changes in climate. The emission of carbon dioxide, methane and the oxides of nitrogen in Nigeria were calculated and trends plotted. A correlation test was also carried out between carbon dioxide emission and temperature change for each zone. The relationship between temperature change and productivity was shown in a regression model. An economic appraisal for Nigeria involving the GDP, pollution and population was examined in terms of the productivity- pollution index. This was also extended to some of the Western countries
87

DETERMINATION OF VERTICAL OZONE PROFILES FROM HIGH-ALTITUDE ULTRAVIOLET SPECTROSCOPY

Rabinoff, Robert Andrew, 1948- January 1975 (has links)
No description available.
88

Investigation of the feasibility of determining the Ozone distribution in a Rayleigh atmosphere by solution of a Fredholm integral equation

Ramos, James Rose, 1936- January 1967 (has links)
No description available.
89

Meteorological investigation of ozone anomalies during the arctic boundary layer experiment (ABLE 3A)

Smarsh, David Anthony 08 1900 (has links)
No description available.
90

A discussion of ozone trends based on sage, SBUV and MLS measurements

Wang, Hsiang-Jui 12 1900 (has links)
No description available.

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