Dissertations / Theses on the topic 'Stratospheric ozone depletion'
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1
Rae, Cameron Davies. "The downward influence of ozone depletion in the Arctic lower stratosphere." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/271796.
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Severe ozone depletion in the polar lower stratosphere has been linked to significant changes in tropospheric circulation patterns in the both hemispheres. Observed Southern Hemisphere circulation changes are easily reproduced in climate models and may be achieved by either increasing ozone depleting substances in a chemistry-climate model(CCM) or by imposing observed ozone losses as a zonally-symmetric perturbation in a prescribed-ozone global circulation model (GCM). In the Northern Hemisphere however, only the CCM method produces a circulation response in agreement with analysis of observations, while the GCM method is unable to produce any significant tropospheric circulation changes from imposing observed zonal-mean Arctic ozone losses. Confidence in a mechanistic link between Arctic stratospheric ozone change and changes in tropospheric circulation is greatly increased if the change can be reproduced using a GCM in addition to being reproducible in a CCM. This thesis demonstrates that by allowing ozone to vary along longitude, and by imposing ozone depletion during a realistic timeframe, the GCM method can produce circulation changes compatible with both the CCM method and observations. An equivalent-latitude coordinate allows the prescribed ozone field, and imposed ozone losses, to follow the polar vortex as it is systematically disturbed or displaced off the pole throughout the winter, producing a realistic circulation response in the troposphere in contrast to when ozone and its imposed losses are zonally-symmetric. Timing the imposed ozone depletion with the breakup of the polar vortex reveals that the appearance of the circulation response is very sensitive to the relative timing of these events and to the pre-existing dynamical state of the polar vortex. These results demonstrate that prescribing ozone as a zonally symmetric climatology within a GCM, as has been recent practice in the literature, is only representative of the Southern Hemisphere and is inappropriate for accurately representing processes within the Arctic stratosphere. Moreover this work demonstrates that these dynamically-evolving zonal asymmetries in ozone, which are not present in zonally-symmetric ozone schemes, play a crucial role in allowing perturbations in the Arctic stratosphere to influence the troposphere and surface conditions.
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Fish, Deborah Jane. "Measurement of stratospheric composition using ultraviolet and visible spectroscopy." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360887.
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Vlachogiannis, Diamando. "The impact of solar proton events on stratospheric zone." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264972.
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Spencer, Darryl Day. "The importance of aluminum oxide aerosols to stratospheric ozone depletion." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41371.
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Kim, Judy E. (Judy Eunhee). "Physical chemistry of acid systems relevant to stratospheric ozone depletion." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/54401.
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Lipson, Jennifer Beth 1972. "Experimental kinetics studies of gas phase halogen reactions involved in stratospheric ozone depletion." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/85291.
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Mantz, Yves André 1974. "Theoretical and experimental studies of heterogeneous chemical processes leading to stratospheric ozone depletion." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/16806.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2002.Vita.
Includes bibliographical references.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
The microscopic chemical mechanisms of heterogeneous reactions involving HC on crystalline ice and nitric acid trihydrate (NAT) are of fundamental interest to physical chemists, because such reactions yield "active" chlorine compounds that are readily photolyzed to yield radicals responsible for the annual destruction of polar stratospheric ozone. Using molecular-orbital and density-functional-based computational methods that are extensively validated, partial dissociation of HCl is shown to be kinetically rapid and thermodynamically favorable on an extended ice Ih surface model with two dangling OH groups in close proximity to adsorbed HCl at a binding site on the surface. Additionally, surface disordering of this ice model is observed at polar stratospheric temperatures when HCl is adsorbed at this site. The partial dissociation of HCl on/atop ice will compete with other proposed mechanisms only if the local density of surface dangling OH groups is high. This alternative mechanism of chlorine activation is not important on NAT, based on the theoretical study of HCl interacting with various low index NAT faces. This is due to the fact that the NAT (001) face (which may be the most prevalent in the polar stratosphere) possesses a low surface density of dangling OH groups. In addition, other selected defect-free low-index NAT faces do not have their dangling OH groups situated favorably for effective partial solvation of HCl. The efficiency of aluminum oxide particulate, which is emitted by solid rocket motors (SRMs), as a catalyst for "activating" chlorine involved in the less dramatic, but still consequential,
(cont.) depletion of ozone at mid-latitudes in the lower stratosphere is also of interest. The pseudo-first-order rate constants for the heterogeneous reaction of ClONO2 + HCl on laboratory a-alumina and actual SRM emissions are measured experimentally using a narrow-bore capillary tube interfaced to a chemical ionization mass spectrometer under reactant partial pressure and temperature conditions typically encountered in the mid-latitude lower stratosphere. Preliminary results indicate that the rate constants are the same. It is likely that the global atmospheric models that employ a reaction probability of 0.02 for ClONO2 + HCl previously measured on laboratory [alpha]-alumina do not need to be revised.
bt Yves André Mantz.
Ph.D.
8
Nebgen, Gilbert Bernard. "Automated Low-cost Instrument for Measuring Total Column Ozone." Thesis, University of North Texas, 2006. https://digital.library.unt.edu/ark:/67531/metadc5792/.
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Networks of ground-based and satellite borne instruments to measure ultraviolet (UV) sunlight and total column ozone have greatly contributed to an understanding of increased amounts of UV reaching the surface of the Earth caused by stratospheric ozone depletion. Increased UV radiation has important potential effects on human health, and agricultural and ecological systems. Observations from these networks make it possible to monitor total ozone decreases and to predict ozone recovery trends due to global efforts to curb the use of products releasing chemicals harmful to the ozone layer. Thus, continued and expanded global monitoring of ozone and UV is needed. However, existing automatic stratospheric ozone monitors are complex and expensive instruments. The main objective of this research was the development of a low-cost fully automated total column ozone monitoring instrument which, because of its affordability, will increase the number of instruments available for ground-based observations. The new instrument is based on a high-resolution fiber optic spectrometer, coupled with fiber optics that are precisely aimed by a pan and tilt positioning mechanism and with controlling programs written in commonly available software platforms which run on a personal computer. This project makes use of novel low-cost fiber optic spectrometer technology. A cost advantage is gained over available units by placing one end of the fiber outdoors to collect sunlight and convey it indoors, thereby allowing the spectrometer and computer to be placed in a controlled environment. This reduces the cost of weatherproofing and thermal compensation. Cost savings also result from a simplified sun targeting system, because only a small pan and tilt device is required to aim the lightweight fiber optic ends. Precision sun-targeting algorithms, optical filter selection, and software to derive ozone from spectral measurements by the spectrometer are a major contribution of this project. This system is a flexible platform which may be adapted to study other atmospheric constituents such as sulfur dioxide, nitrous oxides, and haze.
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Robson, Thomas Matthew. "Response of a peatland ecosystem to stratospheric ozone reduction in Tierra del Fuego." DigitalCommons@USU, 2004. https://digitalcommons.usu.edu/etd/6605.
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Tierra del Fuego, at the southernmost tip of South America, is influenced by ozone depletion. The landscape of southern and western Tierra de! Fuego is dominated by peatlands; they are important locally and in the context of global climate change, because they store large quantities of organic carbon.
To determine the influence of solar ultraviolet-B radiation (UV-B) on a Tierra de! Fuego peatland, we selectively filtered solar UV-Bin ten pairs of plots. Polyfluorine filters were used to create the Near-Ambient-UV-B Treatment ( 90% solar UV-B), and polyester filters to create the Reduced-UV-B Treatment ( 17% solar UV-B). These filters were first installed in October 1996, and were maintained, September-March, for six years. Following previous plant growth measurements and samples of selected microorganisms under the two UV-B treatments (1996-1999), this dissertation is an account of the more detailed measurements made during the second three-year period of treatments (1999-2001 ). Seasonal sampling of the plant community, microfungi, microfauna, and biogeochemistry of the water and nutrients held by the Sphagnum capitulum was introduced, in an attempt to better understand ecosystem function.
Solar UV-B reduced Sphagnum height growth, but this was compensated by more compressed and densely packed Sphagnum capitula. Emergent vascular plants, Nothofagus, Empetrum, and Tetroncium, were more affected than Sphagnum by nearambient UV-B. Solar UV-B altered the Sphagnum-capitulum microenvironment, resulting in: more dissolved organic carbon and phosphorous, higher electrical conductivity, and greater acidity under near-ambient UV-B. Additionally, the populations of testate amoebae and some species of fungi were consistently increased; however, microfungal diversity and rotifer, nematode, and mite populations decreased under near-ambient UV-B.
Generally, Sphagnum minimizes the leaching of nutrients by effectively holding water at the capitulum. Solar UV-B altered Sphagnum-capitulum morphology, increased the volume of water held, and made this water more acidic and richer in nutrients. Based on these results, if current trends in ozone depletion were to persist over several decades, a reduction in vascular plant growth, and changes in the trophic relationships of the microorganismal community of the Sphagnum capitulum, would be predicted. These responses have the potential to affect peatland carbon storage and nutrient cycling in Tierra del Fuego.
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Rkiouak, Laylla. "Mechanism of ozone depletion on the particle candidates for the stratospheric particle injection for a climate engineering project." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709438.
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Zbacnik, Elizabeth A. "The Sensitivity of the Amundsen - Bellingshausen Seas Low to Changes in Greenhouse Gas Concentrations and Stratospheric Ozone Depletion." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1339704028.
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MacKenzie, Ian Atholl. "Quantifying chemical ozone depletion in the polar stratosphere." Thesis, University of Edinburgh, 1995. http://hdl.handle.net/1842/12515.
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Chemical depletion of polar stratospheric ozone occurring during periods of enhanced reactive chlorine concentration in the winter and spring is investigated using both models and observations. A computationally-cheap and easily initialised photochemical model utilising ClO measurements from the Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite is developed. With this model, ozone destruction rates within the polar vortices due to the ClO + ClO, ClO + BrO and ClO + O catalytic cycles are evaluated. The method involves calculating local reactive chlorine concentrations from individual ClO retrievals, and then inferring the diurnal cycle of ClO from a quadratic expression using the relevant kinetic parameters. In test integrations this simple method is shown to give good agreement with more detailed calculations, but its speed of operation and the ease with which the ClO measurements are assimilated make it highly suited to dealing with the large amounts of data generated by MLS. Application of the method to the 1992-1993 Arctic and 1993 Antarctic winters yields maximum vortex-averaged ozone loss rates at 465 K potential temperature of 1% per day in both hemispheres. Time-integrated ozone destruction in the Arctic is less mainly because the duration of temperatures sufficiently low to sustain polar stratospheric clouds (PSCs) is shorter, and hence enhanced reactive chlorine concentrations are less persistent. The estimated chemical destruction on isentropic surfaces in the lower stratosphere is broadly similar to the observed change in ozone distribution, implying that the ozone change is dominated by chemical destruction, with dynamics playing a lesser role. An Antarctic winter-vortex is simulated in a chemical general circulation model (GCM) for the months of August and September. Chemical and dynamical impacts on the ozone change in the model are resolved by contrasting the temporal evolution of the 'chemical' ozone field with that of an inert tracer having the same initial distribution. It is found that the model results are consistent with the MLS-based chemistry-only calculations in indicating that there is very little dynamical replenishment of ozone on isentropic surfaces lying below 500 K. At higher altitudes the model implies a somewhat greater role for the transport than does the chemistry-only analysis.
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Smith, Steven Escar. "Satellite measurements of dinitrogen pentoxide in the stratosphere." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337541.
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Toumi, Ralf. "On the testing of photochemical theories of the stratosphere." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359816.
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Chipperfield, Martyn Paul. "A numerical study of trace gases in the polar stratosphere." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335682.
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Huck, Petra Ellen. "The Coupling of Dynamics and Chemistry in the Antarctic Stratosphere." Thesis, University of Canterbury. Physics and Astronomy, 2007. http://hdl.handle.net/10092/1410.
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This thesis addresses the parameterisation of chemical and dynamical processes in the Antarctic stratosphere. Statistical models for the inter- and intra-annual variability in Antarctic stratospheric ozone depletion were developed based on theory and an understanding of the coupling of dynamics and chemistry in the atmosphere. It was confirmed that the primary driver of the long-term trend in the severity of the Antarctic ozone hole is halogen loading in the stratosphere. The year-to-year variability in ozone mass deficit, a measure of the severity of Antarctic ozone depletion, could be described by a linear combination of South Pole temperatures and midlatitude wave activity. A time lag of two weeks between wave activity effects and ozone depletion indicates the predictive capability of meteorological parameters for seasonal projections of the severity of the Antarctic ozone hole. The statistical model describing the inter-annual variability in ozone mass deficit was regressed against observations from 1979 to 2004. The resulting regression coefficients were applied to South Pole temperature and wave activity fields from 28 chemistry-climate models. This analysis indicates a slight increase in the year-to-year variability in the severity of Antarctic ozone depletion. As a prelude to analysing the seasonal evolution of Antarctic ozone depletion, an improved ozone mass deficit measure was derived by replacing the constant 220 DU threshold with a seasonal varying pre-ozone hole background which leads to better capturing the true extent of the depleted ozone. Furthermore, it was shown that the new measure represents the chemical ozone loss within the Antarctic vortex provided that no mixing occurs through the vortex boundary. This new measure has many advantages over previous stratospheric ozone depletion indices. The conventional ozone mass deficit omits large amounts of depleted mass of ozone, and the onset of ozone depletion does not coincide with the timing of when sunlight first reaches areas of polar stratospheric clouds as expected from theory. Chemical ozone loss derived with a tracer-tracer correlation technique depends on ozone and passive tracer profile measurements which are not as readily available as the total column ozone fields required for the new ozone mass deficit presented in this thesis. As such, the new ozone depletion measure combines the simplicity of the old ozone mass deficit index with higher accuracy of the actual amount of chemically depleted stratospheric ozone. Furthermore, when applying the new definition of ozone mass deficit to chemistry-climate model outputs, model intercomparisons should become easier to interpret because biases in the models can be avoided. Based on theory and understanding of the coupling of chemistry and dynamics in the Antarctic stratosphere, two semi-empirical models were developed to describe the intra-seasonal evolution of chlorine activation and ozone depletion. Regression of the models against chlorine monoxide and ozone mass deficit from observations results in coefficients that capture key sensitivities in the real atmosphere. The seasonal evolution of ozone mass deficit can be described with these coefficients and readily available meteorological fields (temperature and wind fields). The predictive capability of these models was demonstrated for 2005 and 2006. Given temperature and wind fields, which for example can be obtained from general circulation models, these models can predict the size and depth of the Antarctic ozone hole. Important applications of the semi-empirical models could be chemistry-climate model validation by comparing the sensitivities from observations and models which may provide new insights into potential sources of differences in chemistry-climate model projections of Antarctic ozone depletion. Furthermore, projection of the inter-annual and intra-seasonal evolution of the Antarctic ozone hole into the future can help to assess the potential recovery of the Antarctic ozone hole.
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Ferchichi, Olfa. "Étude des propriétés structurales et spectroscopiques de peroxydes aux niveauxDFT et ab initio." Thesis, Reims, 2020. http://www.theses.fr/2020REIMS017.
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Les travaux présentés dans ce manuscrit sont consacrés à l’étude des paramètres structuraux et des spectres IR et UV des trois peroxydes défiant toute description théorique précise pendant plus que trente ans.Le premier résultat atteint dans cette thèse montre que le désaccord entre les expérimentateurs et les théoriciens concernant l'angle de torsion COOC de diméthyl peroxyde s’explique par une structure dynamique avec un mouvement de torsion très lent. Une deuxième étude a été réalisée sur la molécule FOOF pour laquelle les théoriciens ont échoué pendant des décennies à obtenir la bonne structure d'équilibre. Nous avons alors réussi de montrer que la vraie raison est liée à la planéité de la surface d'énergie potentielle, conduisant à des mouvements de grande amplitude. La structure d'équilibre doit être donc moyennée par la vibration pour obtenir des longueurs de liaison précises. La dernière étude est menée sur le peroxyde de chlore, ClOOCl, l'une des molécules clés contribuant à l'appauvrissement de l'ozone stratosphérique. Le premier résultat montre que la structure de ClOOCl doit être moyennée par la vibration tout en incluant les effets de la corrélation core-valence et les effets relativistes pour améliorer les résultats et avoir plus de précision. Le deuxième résultat prouve que la décomposition de ClOOCl en O2 + 2Cl sur les surfaces de l'état excité ne se produit pas en deux étapes, mais suit un mécanisme concerté. Finalement, nous avons demontré que les isomères ClClOO et ClOClO contribuent également à la destruction catalytique de l'ozone. Ces résultats constituent alors une nouvelle découverte sans précédentThis PhD research is devoted to the study of the structural parameters and the IR and UV spectra of three peroxides which have been challenging scientists for many decades. The first result achieved in this thesis shows that the disagreement between experimentalists and theorists concerning the COOC torsional angle of dimethyl peroxide could be explained by a dynamic structure with a very slow torsional movement. A second study was carried out on the FOOF molecule for which theorists had failed, for decades, to obtain an accurate equilibrium structure. We successfully demonstrated that the true reason is related to the flatness of the potential energy surface, leading to large-amplitude motions. The equilibrium structure must therefore be averaged vibrationally to obtain accurate bond lengths. The last study concerns chlorine peroxide, ClOOCl, one of the key molecules contributing to stratospheric ozone depletion. The first result shows that the structure of ClOOCl not only needs to be averaged vibrationally but that core-valence correlation and relativistic effects must also be accounted for. The second result proves that the decomposition of ClOOCl into O2 + 2Cl on excited state surfaces does not occur in two steps, but follows a concerted mechanism. It has finally been demonstrated that the isomers ClClOO and ClOClO also contribute to the catalytic destruction of ozone. These results represent a completely new and unprecedented discovery
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Zhang, Renyi. "Laboratory investigations of heterogeneous chemistry important to ozone depletion in the stratosphere." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12219.
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Butler, Colin David, and Colin Butler@anu edu au. "Inequality and Sustainability." The Australian National University. National Centre for Epidemiology and Population Health, 2002. http://thesis.anu.edu.au./public/adt-ANU20030324.171924.
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Global civilisation, and therefore population health, is threatened by excessive inequality, weapons of mass destruction, inadequate economic and political theory and adverse global environmental change. The unequal distribution of global foreign exchange adjusted income is both a cause and a reflection of global social characteristics responsible for many aspects of these inter-related crises.
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The global distribution of foreign exchange adjusted income for the period 1964-1999 is examined. Using data for more than 99% of the global population, a substantial divergence in its distribution is found. The global Gini co-efficient, adjusted for national income inequality, increased from an already high value of 71% in 1964 to peak at more than 80% in 1995, before falling, very slightly, to 79% in 1999. The global distribution of purchasing parity power income is also examined, for a similar period. Though also found to be extremely unequal, its trend has not been to increased inequality. Implications of the differences between these two trends are discussed.
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A weighted time series index of global environmental change (IGEC) for the period 1960-1997 was also calculated. This uses nine categories of global time series environmental data, each scaled so that 100% represents the level of each category in nature prior to anthropogenic change; zero represents decline to a critical point. This index fell from 82% in 1960 to 55% in 1997, and will further decline during this century.
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Using evidence from several disciplines, it is argued that the decline in the IGEC correlates with major macro-environmental changes, which, combined with flawed social responses to scarcity and its perception, place at risk the ability of civilisation to function. This could occur because of the interaction of conflict, economically disastrous extreme climatic events, deterioration of other ecosystem services, regional food and water insecurity, and currently unforeseen events. Uncertainty regarding both a safe rate of decline and the tolerable nadir of the IGEC is substantial.
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Substantial reduction in the inequality of foreign exchange adjusted income is vital to enhance the development of policies able to reverse the decline in the environmental goods which underpin civilisation, and to promote the co-operation needed to maximise the chance that civilisation will survive.
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Miller, Harlan Laurence. "Photosynthetic response of Scandinavian kelp forests to stratospheric ozone depletion." Thesis, 2002. http://wwwlib.umi.com/cr/utexas/fullcit?p3110659.
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Huck, Petra E. "The coupling of dynamics and chemistry in the Antarctic stratosphere : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Physics in the University of Canterbury /." 2007. http://library.canterbury.ac.nz/etd/adt-NZCU20070913.111048.
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Freedman, Ryan. "Stratospheric minor species densities from satellite measurements of scattered sunlight /." 2005.
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Thesis (M.Sc.)--York University, 2005. Graduate Programme in Earth and Space Science.Typescript. Includes bibliographical references (leaves 139-147). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR11793
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Litfin, Karen. "Power and knowledge in international environmental politics the case of stratospheric ozone depletion /." 1992. http://catalog.hathitrust.org/api/volumes/oclc/28727250.html.
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Ohi, James M. "Science and global environmental pollution issues a case study of stratospheric ozone depletion by chlorofluorocarbons /." 1985. http://catalog.hathitrust.org/api/volumes/oclc/30791600.html.
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Taylor, Timothy. "The Role of Science, Engineering, and Technology in the Public Policy Process for Infrastructure and Natural Systems." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-08-7006.
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Interactions between societal, natural, and infrastructure systems can be
beneficial or harmful to society. Society benefits from natural systems by being provided
with the basic necessities of life (air, water, and food). However, events such as
stratospheric ozone depletion demonstrate that society ultimately can be harmed by
societal impacts on natural systems. Domain knowledge is developed from observation
of natural, societal, and infrastructure systems. Domain knowledge is contained within
scientific knowledge and engineering knowledge. Scientific knowledge is gained
through structured observation and rigorous analysis of natural and societal systems.
Engineering knowledge is partially developed from scientific knowledge and is used to
manipulate natural and societal systems. Technology is the application of engineering
knowledge. In the past two centuries scientific and engineering knowledge have
produced technologies that affect the interaction between societal and natural systems.
Although scientists and engineers are in positions to advise on policies to address
problems involving societal/natural system interactions, their contributions are not
always fully utilized. This research examines feedback mechanisms that describe societal, natural, and
infrastructure system interaction to develop an improved understanding of the dynamic
interactions between society, natural systems, infrastructure systems, scientific and
engineering knowledge, technology, and public policy. These interactions are investing
through and opposing case study analysis performed using computer simulation
modeling. The stratospheric ozone depletion study represents a case in which domain
experts successfully influenced public policy. The U.S. civilian nuclear power study
represents a case in which domain experts were less successful in influencing public
policy. The system dynamics methodology is used to construct these two highly
integrated models of societal-natural system interaction. Individual model sectors, based
on existing theory, describe natural/infrastructure systems, knowledge and technology
development, societal risk perception, and public policy.
The work reveals that the influence of scientists and engineers in the public
policy is due in part to their ability to shift dominance between causal feedback
mechanisms that seek to minimize societal risk from natural systems and feedback
mechanisms that seek to minimize the economic risk of increased regulations. The
ability to alter feedback mechanism dominance is not solely dependent upon scientists
and engineers ability to develop knowledge but to a larger extent depends on their ability
to interact with policy makers and society when describing issues involving natural and
infrastructure systems.
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Fraser, Annemarie. "Arctic and Midlatitude Stratospheric Trace Gas Measurements Using Ground-based UV-visible Spectroscopy." Thesis, 2008. http://hdl.handle.net/1807/17301.
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A ground-based, zenith-sky, UV-visible triple grating spectrometer was installed at the Polar Environment Atmospheric Research Laboratory (PEARL) in the Canadian High Arctic during polar springtime from 2004 to 2007 as part of the Canadian Arctic ACE (Atmospheric Chemistry Experiment) Validation Campaigns. From the solar spectra,
ozone, NO2, and BrO vertical column densities (VCDs) have been retrieved using the DOAS (Differential Optical Absorption Spectroscopy) technique. This spectrometer, the UT-GBS (University of Toronto Ground-Based Spectrometer), was also deployed as part of the fourth Middle Atmosphere Nitrogen TRend Assessment (MANTRA) campaign in Vanscoy, Saskatchewan in August and September 2004.
A near-identical spectrometer, the PEARL-GBS, was permanently installed at PEARL
in August 2006 as part of the refurbishment of the laboratory by CANDAC (Canadian
Network for the Detection of Atmospheric Change). Since then, the instrument has been
making continuous measurements, with the exception of during polar night. Vertical
columns of ozone and NO2 can be retrieved year-round. During the 2007 sunrise campaign,
differential slant column densities (DSCDs) of OClO and VCDs of BrO were also
retrieved.
Ozone and NO2 DSCDs and VCDs from the UT-GBS were compared to the DSCDs and VCDs from three other UV-visible, ground-based, grating spectrometers that also participated in the MANTRA and Eureka campaigns. Two methods developed by the UV-visible Working Group of the NDACC (Network for the Detection of Atmospheric Composition Change) were followed. During MANTRA, the instruments were found to partially meet the NDACC standards. The comparisons from Eureka were an improvement on the MANTRA comparisons, and also partially met the NDACC standards. In 2007, the columns from the UT-GBS and PEARL-GBS were compared, and were found to agree within the NDACC standards for both species.
Ozone and NO2 VCDs from the ground-based instruments were also compared to
integrated partial columns from the ACE-FTS (ACE-Fourier Transform Spectrometer)
and ACE-MAESTRO (ACE-Measurements of Aerosol Extinction in the Stratosphere
and Troposphere Retrieved by Occultation) on board the ACE satellite. ACE-FTS partial
columns were found to agree with the ground-based total columns, while the ACE-MAESTRO
partial columns were found to be smaller than expected for ozone and larger than expected for NO2.
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Parthiban, S. "Theoretical Studies Of XOClO3 (X-ClO2, ClO3, Cl, F And H) And N2O5 : Implications For Stratospheric Ozone Depletion." Thesis, 1996. http://etd.iisc.ernet.in/handle/2005/1574.
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Combrink, Jane. "Ozone maxima over Southern Africa : characteristics and mechanisms." Thesis, 1995. http://hdl.handle.net/10413/5008.
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This thesis aims to clarify the sources of, and mechanisms associated with,
the generation of ozone maxima over the southern African region. Inasmuch as,
tropospheric ozone concentration is a function of both chemistry and
meteorology, this thesis concentrates on the role of atmospheric dynamics.
Firstly, a statistical analysis of the relationship between total ozone and
meteorological parameters revealed a generally weak negative relationship
between total ozone and the height of the 500, 300 and 100 hPa geopotential
surfaces. The relationship is best expressed by the passage of a mid-latitude
cyclone while anticyclonic conditions exhibited a weak relationship. An
examination of the spatial distribution of total ozone and potential vorticity
(PV), during the passage of westerly troughs, prompted a more thorough
investigation of the exchange of ozone between the stratosphere and
troposphere.
The relationship between tropospheric ozone, and low pressure and
anticyclonic systems is investigated further using data obtained during the
South African Fire-Atmospheric Research Initiative (SAFARI) conducted in 1992.
Ozone concentrations, as expressed by ozonesonde data, reveal different
characteristic profiles for the two scenarios. Explanations for the
differences observed are sought in the observed circulation patterns during
the experiment.
Case studies at Okaukuejo (Namibia), Irene (South Africa) and Brazzaville
(Congo), which were utilised as ground stations during SAFARI, are presented
in an attempt to gain insight into the vertical distribution of ozone over the
entire expanse of the study region. The role of convective systems in the
generation of short-lived upper tropospheric ozone maxima at tropical
latitudes is illustrated while the different vertical ozone signatures,
expressed under cyclonic and anticyclonic systems as described earlier, are
reconfirmed by the Okaukuejo and Irene data.
An attempt is made to investigate dynamic links between the troposphere and
stratosphere and the concomitant exchange of ozone during the passage of
westerly trough systems. Particularly deep troughs or cut off low pressure
systems are identified as important mechanisms in the generation of upper
tropospheric ozone maxima. An examination of the vertical distribution of
ozone at Irene during the passage of a COL, using data obtained from the
SA'ARI 1994 experiment, suggests concurrence with Danielsen's (1968) model of
tropopause folding. The intrusion of high PV and dry stratospheric air,
coupled with downward flow near the tropopause, in the vicinity of the upper
tropospheric disturbance, promotes the transport of ozone-rich air to
tropospheric altitudes.
The limited availability of data has severely hampered the understanding of
tropospheric ozo~e in southern Africa in the past. This study demonstrates the
value of daily vertical ozone data, even for very short periods.Thesis (Ph.D.)-University of Natal, 1995.
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Butler, Colin. "Inequality and Sustainability." Phd thesis, 2002. http://hdl.handle.net/1885/46233.
Full textAbstract:
Global civilisation, and therefore population health, is threatened by excessive inequality, weapons of mass destruction, inadequate economic and political theory and adverse global environmental change. The unequal distribution of global foreign exchange adjusted income is both a cause and a reflection of global social characteristics responsible for many aspects of these inter-related crises. ¶ The global distribution of foreign exchange adjusted income for the period 1964-1999 is examined. Using data for more than 99% of the global population, a substantial divergence in its distribution is found. The global Gini co-efficient, adjusted for national income inequality, increased from an already high value of 71% in 1964 to peak at more than 80% in 1995, before falling, very slightly, to 79% in 1999. The global distribution of purchasing parity power income is also examined, for a similar period. Though also found to be extremely unequal, its trend has not been to increased inequality. Implications of the differences between these two trends are discussed. ...