La qualité de l’air est un enjeu environnemental majeur de notre société. Cette thèse se focalise sur l’observation depuis l’espace du polluant gazeux majeur, l’ozone troposphérique. Les instruments satellitaires de nouvelle génération permettent de le mesurer journalièrement aux échelles régionales à globale. Cependant, les mesures d’un seul domaine spectral n’amène pas d’information suffisante pour quantifier les concentrations de l’ozone dans la couche limite atmosphérique, où se situe l’air que nous respirons. Le couplage des mesures de multiples domaines spectraux offre un fort potentiel pour mieux caractériser la pollution à l’ozone. La première approche multispectrale à 2 bandes combinant les mesures de l’infrarouge (IR) de IASI et l’ultraviolet (UV) de GOME-2 a été développée au laboratoire LISA, que j’ai intégré dans le cadre de ma thèse. L’objectif de mon travail de thèse est de franchir un pas supplémentaire dans la quantification de la pollution à l’ozone en incluant la bande visible (VIS) de Chappuis, afin de développer un couplage multispectral inédit à trois bandes spectrales UV+VIS+IR. Premièrement, j’ai mis au point une approche pour extraire l’information sur l’ozone des spectres VIS de GOME-2, en sélectionnant les longueurs d’onde affectées majoritairement par l’absorption à l’ozone et rejetant celles avec des absorptions d’autres gaz, ainsi que déterminant les variables d’ajustement conjoint de l’approche (profil vertical d’ozone, albédo de surface, shifts spectraux, etc) et les bases de données nécessaires pour simuler les spectres VIS (albédo de surface, spectroscopie).Ensuite, j’ai mis en œuvre la méthode multispectrale à trois bandes UV+VIS+IR, premièrement sur des observations simulées défilantes de IASI et GOME-2 et géostationnaires de MAGEAQ afin d’estimer l’amélioration en terme de sensibilité et précision, par rapport aux méthodes existantes. Dernièrement, j’ai appliqué l’approche multispectrale à 3 bandes à des observations satellitaires réelles de IASI et GOME-2. Des comparaisons avec d’autres données montrent des meilleures performances des nouvelles observations UV+VIS+IR pour caractériser des évènements de pollution à l’ozone, par rapport à l’approche à 2 bandes / Air quality is a major environmental issue for our society. This PhD thesis focuses on space borne observation of the major gaseous pollutant. Tropospheric ozone. New generation satellite instruments allow measuring it daily at regional to global scales. However, single spectral domain measurements do not provide enough information for quantifying ozone concentrations at the atmospheric boundary layer, where the air we breathe is located. Synergism of measurements from multiple spectral domains offers a great potential for better characterizing ozone pollution. The first 2-band multispectral approach combining infrared (IR) measurements of IASI and the ultraviolet (UV) of GOME-2 was developed at LISA laboratory, where I conducted my thesis. The goal of my thesis is to go a step further in the quantification of ozone pollution by including the visible (VIS) Chappuis band, in order to develop an unprecedented 3-band multispectral synergism UV+VIS+IR. First, I developed a approach for extracting ozone information from GOME-2 VIS spectra, by selecting the wavelengths mostly affected by ozone absorption and rejecting those with absorptions from other gases, as well as determining the joint adjustment variables of the approach (vertical ozone profile, surface albedo, spectral shifts, etc) and the databases needed to simulate the spectra VIS (surface albedo, spectroscopy).Then, I implemented the multispectral method with three bands UV+VIS+IR, first on simulated low-orbit and geostationary observations from respectively IASI and GOME-2 and MAGEAQ to estimate the improvement in terms of sensitivity and precision, as compared to existing methods. Last, I applied the 3-band multispectral approach to real satellite observations of IASI and GOME-2. Comparisons with other data shows enhanced performances of the new UV+VIS+IR observations to characterize ozone pollution events, with respect to the 2-band approach

Graduation date: 1994

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Over the past 2001~2005 years, the ozone concentration of Kaohsiung county had a rising trend year by year. It¡¦s one of the main reasons that air quality was bad in Kaohsiung and Pingtung Counties. In order to reach the purpose to improve the ozone and air quality effectively, we need to make the whole investigation and of the ozone precursors VOCs and NOx. In addition, the ozone concentration is also influenced by factors, such as intensity of sunshine, temperature, humidity, rainfall, and speed of wind direction, etc. This research mainly investigated the distributing of the ozone precursors of the vertical height and the photochemical ozone formation reactivity with sounding for the 22nd ¡Vthe 25th of November in the Lin-Yuan petrochemical industrial park to discuss the relation of synoptic systems and meteorological parameterization, as the reference used in controlling ozone concentration. It is known the comprehensive synoptic systems are Northeasterly Monsoon Winds type by the analysis of the meteorological parameterization. The station of fishers association was the downwind position and the station of sin-yuan elementary school was the upwind position. The sea-land breeze, that is normally low-latitude (under about 700 meters) regional wind or local circulation, causes the position change of upper and lower wind. The whole trend of ozone and speed of wind of the two stations had negative correlation obviously and the correlation was bad for the height under 500 meters. The whole trend of ozone and NMHC was negative correlation in range of 100m to 300m that was better than above 500 meters. The whole trend of ozone and NOx was negative correlation in the height of 100 meters and had no correlation in above 300 meters. It shows that correlation of O3 and NOx is relatived to source of NOx pollution and is decreased with the altitude height.

Thesis (M. Sc)--York University, 2000. Graduate Programme in Physics and Astronomy. / Typescript. Includes bibliographical references (leaves 128-135). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ59206.

A fast response chemiluminescent ozone sonde originally intended for use as a balloon borne instrument, was deployed on a single engine light aircraft to determine mean ozone concentrations in the boundary layer downwind of a major urban centre. Vancouver is a coastal city at the mouth of a major river delta and valley walled in by mountains to the north and east. Hence, the pollutant distribution during anti-cyclonic conditions is influenced by the thermally induced flows of the sea/land breeze and mountain/valley wind systems. This study focused on ozone concentration in a steep walled, glacial valley near the city, where ozone concentrations had not been previously monitored but were suspected to be high. Measurements confirmed this hypothesis and the mass budget of ozone for the valley was calculated for a period shortly after sunrise when the rate of boundary layer growth was at its maximum. The high levels of ozone found in the valley were partly attributed to residual layer storage of ozone above the nocturnal stable layer. This overnight storage of ozone during sustained anti-cyclonic conditions suggests that the Pitt River valley and possibly other tributary valleys represent an important net sink for ozone emanating from precursor sources in the Lower Fraser Valley.

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Planetary waves are known to play an important role in determining the annual variability in the severity of Antarctic ozone depletion. In this thesis, data obtained from the TOMS experiment on board the Nimbus-7 satellite are used to create global maps of total column ozone for each day from 1979 to 1992. Planetary wave morphology within these distributions is examined using spatial spectral analysis. The wave powers obtained are compared with a measure of the depth and area of the Antarctic ozone hole. A theoretical overview is given of middle atmosphere dynamics and how it influences the global distribution of ozone. Planetary waves play a predominant role in this dynamical distribution as they are responsible for the eddy transport of heat, momentum and long-lived tracers. A discussion of the equations of motion governing planetary wave propagation and their physical interpretation is given. The use of derived meteorological parameters, such as potential vorticity, in the study of planetary waves is developed. The theoretical tools, together with the equations of motion, are used to examine the excitation mechanisms for planetary waves. This theoretical analysis is also used to show that the strength of the westerly jet within the polar vortex determines which planetary wave modes can be expected in the geopotential height fields. In general only wavenumber 1 and 2 propagate during the Southern Hemisphere winter and the strength of these waves strongly modulates the severity of the Antarctic ozone depletion. Furthermore, the timing of the breakdown of the polar vortex is connected with the temporal variation of planetary wave power. A review of the current research in the field of planetary waves and the global distribution of ozone is given. To quantify planetary wave activity, spatial spectral analysis (Fourier Transforms) of midlatitude zonal profiles of total column ozone are used to calculate wave powers in the ozone distribution. Powers at wavenumber 1 to 6 are calculated for each day from 1979 to 1992 for both the Northern and Southern Hemispheres. The powers are seen to decrease with wavenumber throughout the year and the amplitude of wave modes 3 and higher is suppressed during the winter in accordance with the theoretical discussion. Southern Hemisphere wave powers are compared with a daily depleted mass of ozone over the Antarctic from 1979 to 1992. It is found that during years of high (low) planetary wave activity Antarctic ozone depletion is very weak (severe). Finally, the planetary wave morphology observed in the Southern Hemisphere total column ozone distribution is compared with geopotential height waves reported in the literature. Comparison of Northern Hemisphere wave powers and Arctic ozone depletion shows little or no correlation. To examine whether planetary waves may effect the interannual variability in Antarctic vortex temperatures, winter averaged 100 hPa upper air temperatures from SANAE (70°18' S, 2°21' W) are compared with derived planetary wave powers. It is found that during years of high (low) planetary wave activity the SANAE 100 hPa temperatures are above (below) the mean. Analysis of daily total column ozone and upper air temperatures at SANAE, during the winters of 1987 and 1988, shows that wave 1 forcing can significantly influence the day-to-day variation in these quantities. A statistical model of total ozone variation over the entire globe, from 1979 to 1992, has been developed. This model incorporates a long-term linear trend, an annual variation, a quasi-biennial oscillation, a solar cycle variation and a semiannual variation. Since monthly average total column ozone data are used in this model, short term planetary wave influences are masked, and the variations in global ozone are determined primarily by the 5 signals discussed above. However, analysis of the model coefficients indicates that planetary wave activity may significantly contribute to zonal asymmetry in global total ozone trends. Differences between model results and measured data are compared with planetary wave activity. The timing of the breakdown of the Antarctic circumpolar vortex causes large interannual differences in monthly average total column ozone for the months of October and November in the Southern Hemisphere. This analysis is made more specific for South Africa by examining the variation in monthly average total column ozone over the five South African cities of Pretoria, Bloemfontein, Durban, Port Elizabeth and Cape Town for the years 1979 to 1992. A model of surface erythemal irradiance as a function of total column ozone, time of the year and other meteorological parameters is developed. Total ozone data for the 5 cities, used within the context of the statistical model and the DV irradiance model, allows the prediction of future DV levels over South Africa to the year 2000. Planetary wave motion owes its existence to the conservation of potential vor-ticity. However, to make use of this conservation principle as a diagnostic for planetary wave propagation, it is necessary to know the conditions under which it is conserved. A formalism developed by Plumb and Ko (1992) has been used to suggest a technique whereby the 'lifetime' of potential vorticity may be determined. Use was made of data from the NCAR CCM2 model to test this hypothesis. The concentrations of long-lived tracers (CH4 and NzO) extracted from the CCM2 also show the effects of planetary wave breaking on the meridional distribution of these species. This study has important implications for airborne polar chemistry campaigns. / Thesis (Ph.D.)-University of Natal, 1994.

The photodissociation of ozone by ultraviolet light has a great impact on the photochemistry of the atmosphere. The relative quantum yield for the production of the singlet atomic fragment O(¹D) has been determined in the wavelength region 306 to 327 nm for four temperatures between 227 K and 300 K. The technique of resonance enhanced multi photon ionisation (REMPI) was used to probe directly the O(¹D) photolysis product. These relative measurements have been placed onto an absolute scale by the selection of a calibration point whose value has been agreed by the scientific community. The yields obtained are in good agreement with others reported during the time of the research reported in this thesis and clearly show that three mechanisms contribute to the final quantum yield. Below 310 nm, O(¹D) is produced by a spin-allowed channel, above 320 nm the primary channel is a spin- forbidden one and at intermediate wavelengths photolysis of vibrationally excited ozone contributes to the O(¹D) yield. Elements of the quantum yield data presented in this thesis are being included in a new recommendation for the temperature dependent O(¹D) quantum yield. Details of the dissociation kinetics, including further evidence confirming the spin-forbidden channel, is presented in time-of-flight studies of the O(¹D) product. Time-of-flight profiles taken between 317 and 321 nm show evidence that, at room temperature, the O(¹D) quantum yield is anti-correlated with the ozone absorption cross section. Excitation of the O₂(a¹Δ_g) co-fragment has been observed at wavelengths below 296 nm by monitoring the energies of the O(¹D) formed. As the channel for the production of O₂(a¹Δ_g,andnbsp;vandnbsp;=andnbsp;1) opens, it is found that energy is preferentially partitioned into rotation of the O₂ fragment rather than into translation. Initial studies on the O(¹D) fragment have shown that the fragment is orbitally aligned and that the choice of REMPI transition can have a significant effect on the time-of-flight profiles and therefore on the measurements that are made from the profiles. The time-of-flight profiles obtained by probing the O₂(a¹Δ_g) photofragment have shown that the O₂(a¹Δ_g) has an angular momentum polarisation that is J dependent, with the even J being strongly polarised and the odd J depolarised. This results in the shape of the time-of-flight profiles being a function of the REMPI laser polarisation; and the study of this behaviour has been used to confirm the assignments in highly perturbed REMPI spectra.