Atmospheric mass is transported in and out of the stratospheric polar cap region by a wave-driven meridional circulation. Using composites of polar cap pressure anomalies, defined as deviations from the average annual cycle, it is shown that this stratospheric mass flux is accompanied by a similar mass flux near the surface. This 'tropospheric amplification' of the stratospheric signal is introduced as a new way to quantify stratosphere-troposphere coupling. Regression analysis is used to create a vertical profile of atmospheric pressure during a tropospheric amplification event, and the regression slope profile is used as a tool to quantify the amplification. Using data from 5 reanalysis datasets and 11 climate models, it is shown that high-top models, with a model lid of above 1 hPa, are significantly better at reproducing tropospheric amplification than low-top models, due to having more detailed parameterisations of stratospheric processes. However, the regression slope profiles of all models, bar one, are significantly different to the profile of reanalysis data at a 95% confidence level. Tropospheric amplification is also investigated in historical and future simulations from these models, and it is concluded that there is not expected to be a large change in the phenomenon over the next 100 years. The processes needed to reproduce tropospheric amplification can be identified by comparing idealised models of different complexity. A simple dry-core model is not able to reproduce tropospheric amplification, while a model with a comprehensive radiation scheme does produce the basic regression slope profile under certain configurations. The associations between pressure change and mass flux are further investigated using primitive equations. It is found that vertical and horizontal contributions to mass flux act to mostly cancel each other out, leaving a poorly-conditioned residual, and that the horizontal mass flux across the polar cap boundary has both geostrophic and ageostrophic components.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O presente estudo teve como objetivo quantificar as emissões de Compostos Orgânicos Voláteis do Aterro Controlado Morro do Céu localizado na cidade de Niterói, Rio de Janeiro, Brasil. Para tanto, vinte amostras foram coletadas, usando uma bomba de ar operada a bateria durante dois dias de dezembro de 2009. Uma câmara de fluxo cilíndrica de PVC de 30L foi inserida 5 cm no solo do aterro, e as amostras foram coletadas através de uma válvula na parte superior da câmera. Os resultados indicaram um valor de 1.980 Kg Km-2 h-1. O modelo Gaussiano de dispersão atmosférica ISCST3 foi utilizado para calcular a difusão e transporte dos poluentes a fim de estimar as concentrações de COV no bairro, usando dados topográficos, meteorológicos e de emissões. Valores de 525 μg m-3 de COV foram encontrados a 500 metros do aterro. As emissões do aterro foram usadas em conjunto com dados meteorológicos, utilizando o modelo de trajetória OZIPR e o mecanismo químico SAPRC para demonstrar o impacto na formação do ozônio troposférico na região. É conhecido que o ozônio é formado pela reação entre COV, NOx e luz solar. A contribuição de valores elevados de COV provenientes das emissões do aterro conduzirá a uma nova situação com valores mais elevados de ozônio na região. Os resultados da modelagem indicaram um aumento maior que 1000% nos níveis de ozônio na região do aterro, se comparado com a modelagem do ozônio para a região metropolitana do Rio de Janeiro. Os resultados mostram ser necessário que maior atenção seja dada à política de gerenciamento de RSU no Brasil, incluindo a escolha adequada para o local de instalação, o monitoramento da área durante e após o período de operação e técnicas mais adequadas de disposição dos resíduos sólidos urbanos / The purpose of this work was to quantify the Volatile Organic Compounds emissions by a landfill (Morro do Céu), located in Niterói, Rio de Janeiro State, Brazil. Twenty 10-minute samples were collected using a battery-operated air pump operated at 500 mL min-1, over a period of four days in May and December, 2009. A cylindrical 30 L PVC flux chamber was used, the open, bottom side of which was inserted into the landfill soil to a depth of 5 cm. The samples were collected using a valve at the upper, closed side of the chamber. The results indicated an elevated value of 1,980 kg km-2 h-1. A Gaussian plume dispersion model, implemented by Aermod software, was used to calculate the diffusion and transport of pollutants, and the pollutant concentrations in the surroundings were estimated using the emission, meteorological, and topographical data. Maximum values of 525 μg m-3 for VOC were found at approximately 500 m from the landfill. The landfill emissions were also compiled with meteorological data, using the OZIPR trajectory model coupled with SAPRC chemical mechanism, to demonstrate their impact on the formation of tropospheric ozone. It is well known that ozone is formed by the reactions of VOC, NOx and sunlight. The contribution of high VOC levels from the landfill emissions was expected to lead to higher ozone values. The results indicated a 1000% increase in ozone in the region of the landfill, compared to the ozone values for the metropolitan region of Rio de Janeiro. The results show that it is both necessary and desirable that greater attention be given to the political management of municipal solid waste in the Brazil, including the location choice, the monitoring of landfill areas during and after their period of operation and techniques more appropriate of disposition of municipal solid waste

O monitoramento dos poluentes atmosféricos é um dos principais itens para a gestão do ar em centros urbanos e rurais atualmente. Entretanto, os altos custos de infraestrutura e de manutenção das estações de monitoramento da qualidade do ar inviabilizam muitos países, estados e municípios de implementarem esse intrumento. No Brasil, a gestão da qualidade do ar é restrita a alguns estados. No caso do monitoramento da qualidade do ar, a medida é restrita a algumas cidades. A fim de contribuir com o entendimento dos níveis de ozônio em uma cidade do interior paulista, foram conduzidas vinte e seis campanhas de amostragem semanal do ozônio tropósférico entre setembro de 2016 e setembro de 2017, em Jundiaí. Foram investigadas algumas características que são determinantes para a ocorrência do poluente ao longo das quatro estações e a variação em sete bairros do município. Com o propósito de avaliar o desempenho dos amostradores passivo frente as medições do monitor automático da CETESB, um dos locais selecionados foi a estação de monitoramento da CETESB. Em relação aos sete bairros, contatou-se diferença estatística (p<0,05) através da aplicação da Análise de Variância (ANOVA), sendo constatada diferença em um local do município com o teste de Dunnett. Nas amostras coletadas na estação da CETESB, observou-se correlação da temperatura e a umidade relativa do ar com o ozônio. Essas variáveis inseridas em um modelo de regressão com as amostragens passivas resultou na explicação de 92% (r2=0,921) das medições realizadas pelo monitor automático da CETESB. Por meio da análise das retrotrajetórias de parcelas de ar foi possível verificar que as concentrações de ozônio em Jundiaí possivelmente sejam influenciadas pelas emissões de outras regiões. Além disso, propôs-se contribuir com o desenvolvimento de novas técnicas de monitoramento de ozônio, montando e validando preliminarmente um dispositivo de baixo custo com um sensor programado no hardware Arduino. Foi feita a calibração indireta do dispositivo de medição de ozônio com o monitor automático da CETESB. Observou-se que os resultados obtidos pelo dispositivo não apresentaram correlação com os do monitor da CETESB (p>0,05), ainda que o primeiro e segundo quartis tenham apresentado correlação (p<0,05). O dispositivo precisa ser mais bem avaliado com calibração em laboratório. / Monitoring of air pollutants is one the main items for air management in urban and rural centers today. However, the high costs of infrastructure and maintenance of air quality monitoring stations manke many countries, states and municipalities unable to implement this instrument. In Brazil air quality management is restrict to some states. In the case of air quality monitoring, the measure is restricted to some cities. In order to contribuite to the understanding of ozone levels in a city in the state of São Paulo, twenty-six weekly sampling campaigns of tropospheric ozone between September 2016 and Sptember 2017 in Jundiaí. It was investigated some characteristics that are determinant for the occurance of the pollutant throughout the four seasons and the variation in seven districts os the Jundiaí. In order to evaluate the performance of the passive samplers against the CETESB automatic monitor measurements, one of the selected sites was the monitoring station of CETESB. About the seven neighborhoods, a statistical difference (p<0.05) was applied through the Analysis of Variace (ANOVA), and a difference was found in one locality of the municipality with the Dunnett test. In the samples collected at the CETESB station, a correlation was observed between temperature and air humidity and ozone. These variables inserted in a regression model with the passive samplings resulted in the explanation of 92% (r²=0.921) of the measurements performed by the CETESB automatic monitor. By analyzing the backward trajectories of air parcels, it was possible to verify that ozone concentrations in Jundiaí are possibly influenced by emissions from other regions. In addition, it was proposed to contribute to the development of new ozone monitoring techniques by assembling and preliminarily validating a low-cost device with a sensor programmed into Arduino hardware. The indirect calibration of the ozone measuring device was done with the CETESB automatic monitor. It was observed that the results obtained by the device did not correlate with those of the CETESB monitor (p>0.05), although the first and second quartiles showed a correlation (p<0.05). The device needs to be better evaluated with laboratory calibration.

The monitoring and study of the earth�s atmosphere is becoming an increasingly important task given the current uncertainties in climate prediction. Areas where lidar has been used to further understanding of the atmosphere include monitoring of greenhouse gases, global warming, stratospheric ozone depletion, photochemical smog and aerosol photochemistry. However, the potentially severe long term effects of anthropogenic aerosols on earth�s biosphere are poorly understood. This project seeks to apply state of the art laser technology to develop an innovative multiwavelength lidar system capable of providing new information and new insights into the field of tropospheric aerosol lidar. Several novel tunable laser and laser-like sources have been investigated and developed for the purpose of tropospheric aerosol lidar at The National Institute of Water and Atmospheric Research (Niwa), Central Otago. Multiwavelength operation in the visible and near infrared portion of the spectrum has been emphasised with the sources developed collectively spanning the wavelength interval of 400-1369 nm. The laser sources investigated were the LiF:F2+ colour centre, Titanium Sapphire (Ti:sapphire) and barium nitrate Raman lasers. In addition to the laser sources, the β-barium borate optical parametric oscillator (BBO OPO) was characterised. For each of the sources, lidar relevant aspects were studied. The results recorded include conversion efficiency with respect to the pump source, linewidth and tuning characteristics, beam quality, temporal behaviour, and device reliability and ruggedness. It was found that the LiF:F2+ laser offered significantly lower threshold, broader tuning and higher output pulse energies than the Ti:sapphire laser in the 900-1000 nm region. The high optical gain of the LiF:F2+ medium facilitated cavity optical alignment and operation of the system. The high gain also resulted in temporal behaviour well suited to the existing Niwa lidar detection scheme. When using a 5 ns pump source, amplified spontaneous emission (ASE) was found to limit the laser tuning range and efficiency. The barium nitrate Raman laser was based on a simple linear cavity arrangement which resulted in a compact and robust device with no moving components. The stimulated Raman scattering process offers relatively narrow linewidth laser operation at the first and second Stokes wavelengths of 1197 nm and 1369 nm respectively. This laser offered efficient operation once the high operation threshold was reached. Second harmonic generation was used to extend the number of potential lidar transmitter lines produced. The barium nitrate Raman laser possessed high beam divergence and a maximum of three discrete transmitter wavelengths. The BBO OPO used a type I collinear signal resonant configuration. A plane-plane cavity configuration with pump reflection was found to provide simplicity of design, low threshold, highly efficient operation and output pointing stability. The BBO OPO signal wavelength could be tuned over the wavelength interval of 400-700 nm. The disadvantage of the plane cavity was high output beam divergence. However, this was successfully brought within the required limits through the use of a 40 mm long cavity in conjunction with an expanding and collimating telescope. As a result of the study, a Tunable lidar Transmitter (TLT) system based on the BBO OPO was designed and constructed at the Physics Department. The TLT was computer-controlled using custom written software and constructed in a self contained modular manner with all required mechanical, electrical and optical components. A user manual was also written to accompany the TLT. The TLT was installed at Niwa and was successfully used to gather preliminary multiwavelength lidar data. The TLT BBO OPO threshold occurred for a pump energy of 5.2 mJ (10.6 MW/cm2) and had a maximum slope efficiency of 53%. Signal efficiency varied from 24-41-35% over the intervals of 410-500-600 nm. A maximum signal energy of 21 mJ was obtained for a signal wavelength of 492 nm when using the maximum available pump energy of 42 mJ. OPO signal linewidth varied from 0.1-1-8 nm over the signal wavelength intervals of 400-600-700 nm. The associated OPO finesse varied between 370 and 100 as the signal wavelength was tuned over the wavelength interval of 400-600 nm. The temporal behaviour of the BBO OPO was a slowly varying function of pump energy and closely followed the temporal behaviour of the pump laser, making it well suited to the existing Italian lidar detection and timing scheme.

With the increasing availability of observational data from different sources at a global level, joint analysis of these data is becoming especially attractive. For such an analysis – oftentimes with little prior knowledge about local and global interactions between the different observational variables at hand – an exploratory, data-driven analysis of the data may be of particular relevance. In the present work we used generalized additive models (GAM) in an exemplary study of spatio-temporal patterns in the tropospheric NO2-distribution derived from GOME satellite observations (1996 to 2001) at global scale. We focused on identifying correlations between NO2 and local wind fields, a quantity which is of particular interest in the analysis of spatio-temporal interactions. Formulating general functional, parametric relationships between the observed NO2 distribution and local wind fields, however, is difficult – if not impossible. So, rather than following a modelbased analysis testing the data for predefined hypotheses (assuming, for example, sinusoidal seasonal trends), we used a GAM with non-parametric model terms to learn this functional relationship between NO2 and wind directly from the data. The NO2 observations showed to be affected by winddominated processes over large areas. We estimated the extent of areas affected by specific NO2 emission sources, and were able to highlight likely atmospheric transport “pathways”. General temporal trends which were also part of our model – weekly, seasonal and linear changes – showed to be in good agreement with previous studies and alternative ways of analysing the time series. Overall, using a non-parametric model provided favorable means for a rapid inspection of this large spatio-temporal NO2 data set, with less bias than parametric approaches, and allowing to visualize dynamical processes of the NO2 distribution at a global scale.

The abatement of ground-level ozone has been a priority of air pollution policy because of its harmful effects on human health, ecosystems, and climate. The responsiveness of ozone to emissions of its principal precursors, nitrogen oxides (NOx) and volatile organic compounds (VOCs), is known to depend nonlinearly on spatially and temporally variable factors. Given this variability, scientific understanding of ozone formation processes can facilitate the development of sensible control policies. This thesis applies a high-order sensitivity analysis technique, the Decoupled Direct Method in Three Dimensions (HDDM-3D), to examine ozone response to precursor emissions during summertime air pollution episodes in the southeastern United States. HDDM-3D is shown to accurately capture ozone response within an underlying air quality model, even over large ranges of emission perturbations. Nonlinearity of response is quantified, and nonlinear terms are applied to examine how estimates of sensitivity and source attribution respond to uncertainty in an emissions inventory. Ozone production regime is assessed using both HDDM-3D and species indicator ratios and found to be primarily NOx-limited outside urban centers. However, ozone response to region-wide emissions does not necessarily correspond to its sensitivity to local controls, hindering the usefulness of bipartite ozone regime classification. Significant heterogeneity of ozone response to NOx is found even over small spatial scales of emission origin, a potential complication often ignored in atmospheric modeling and emissions trading mechanisms. Atmospheric sensitivity analysis is linked with a comprehensive menu of potential control measures to demonstrate potential integration of scientific and economic considerations for control strategy formulation. Cost-optimized strategies are identified for attainment of federal ozone standards in Macon, Georgia, and for minimizing potential population exposure to unhealthful concentrations of ozone.

This study presents airborne measurements of HO2NO2, HCl and SO2 using chemical ionization mass spectrometry (CIMS) during the Intercontinental Chemical Transport Experiment (INTEX) field campaign, an intensive study to characterize the chemical composition of the troposphere in the eastern United States, Mexico City, and the North Pacific which is the outflow region of Asia. The first direct in situ measurements of HO2NO2 were made in the free troposphere over the eastern U.S. during summer 2004. The highest mean mixing ratio of 76 pptv (median = 77 pptv, = 39 pptv) was observed in the altitude range of 8-9 km. Highly constrained steady state calculations of HO2NO2 using measured HOx levels are poorly correlated with observed HO2NO2 in the upper troposphere (8 km < z < 12 km; the median ratio of [HO2NO2]SS-MEA/[HO2NO2]MEA = 2.9). However, steady state HO2NO2 using model-derived HOx shows reasonable agreement with measurements in the free troposphere ([HO2NO2]SS-MEA/[HO2NO2]MEA = 1.3). The vertical distribution of HCl was measured over the north Pacific during May 2006 from the marine boundary layer (MBL) up to lower stratosphere. Recent stratospheric influence in the upper troposphere (8 km < z < 12 km) was efficiently identified from enhanced HCl (up to ~100 pptv) relative to very low background levels (< 2pptv). In the remote MBL, the acidification of seasalt aerosols by HNO3 appeared to be the major source of HCl, with level consistently over 20 pptv (up to 400 pptv). The distribution of SO2 was measured in the outflow region of the eastern U.S. and Asia; two major anthropogenic SO2 source regions. This study presents vertical and horizontal distributions of SO2 and relevant gas phase and aerosol parameters to characterize SO2 transport in the troposphere. SO2 in the boundary layer was efficiently transported to the upper troposphere by deep convection and frontal uplift processes. High SO2 in convective plume in the upper troposphere were strongly correlated with ultrafine aerosols.Conversely, SO2 from frontal uplift shows a strong correlation with non-volatile aerosols. Comparisons of SO2 products from global 3-D chemical transportation models (GEOS-CHEM and MOZART) with observations suggest that sulfur sources are relatively well described but that the oxidation mechanism needs refinement.

The rapid rising anthropogenic emissions driven by economic growth over China documented by satellite observations and bottom-up inventories have led to severely degraded air quality, and also have been suggested to be linked to the recent upward trends of tropospheric O₃ over the regions downwind of China. Multi-scale modeling analyses facilitated by ground-level, aircraft and satellite observations have been conducted to understand the atmospheric chemistry over China. Analyses using a 1-D photochemical model constrained by measurements at Beijing in August of 2007 suggest that reactive aromatic VOCs are the major source (~75%) of peroxy acetyl nitrate (PAN). Detailed radical budget analyses reveal the very fast ROₓ (OH + HO₂ + RO₂) production, recycling and destruction driven by VOC oxidation and heterogeneous processes. Photoenhanced aerosol surface uptake of NO₂ is found to be the predominant source of nitrous acid (HONO) during daytime (~70%). 3-D regional modeling analyses of tropospheric vertical column densities of glyoxal (CHOCHO) from SCIAMACHY show that anthropogenic emissions of aromatic VOCs are substantially underestimated (by a factor of 5 - 6, regionally varied) over China. Such an underestimation is the main cause of a large missing source of CHOCHO over the region in current global models, and could also partly explain the underestimation of organic aerosols in previous modeling studies.

The Global Positioning System (GPS) has been used for more than a decade for the accurate determination of position on the earth's surface, as well as navigation. The system consists of approximately thirty satellites, managed by the US Department of Defense, orbiting at an altitude of 20 200 kilometres, as well as thousands of stationary ground-based and mobile receivers. It has become apparent from numerous studies that the delay of GPS signals in the atmosphere can also be used to study the amosphere, particularly to determine the precipitable water vapour (PWV) content of the troposphere and the total electron content (TEC) of the ionosphere. This dissertation gives an overview of the mechanisms that contribute to the delay of radio signals between satellites and receivers. The dissertation then focuses on software developed at the Hartebeesthoek Radio Astronomy Observatory's (HartRAO's) Space Geodesy Programme to estimate tropospheric delays (from which PWV is calculated) in near real-time. In addition an application of this technique, namely the improvement of tropospheric delay models used to process satellite laser ranging (SLR) data, is investigated. The dissertation concludes with a discussion of opportunities for future work. / Thesis (M.Sc. (Physics))--North-West University, Potchefstroom Campus, 2004.

The Global Positioning System (GPS) has been used for more than a decade for the accurate determination of position on the earth's surface, as well as navigation. The system consists of approximately thirty satellites, managed by the US Department of Defense, orbiting at an altitude of 20 200 kilometres, as well as thousands of stationary ground-based and mobile receivers. It has become apparent from numerous studies that the delay of GPS signals in the atmosphere can also be used to study the amosphere, particularly to determine the precipitable water vapour (PWV) content of the troposphere and the total electron content (TEC) of the ionosphere. This dissertation gives an overview of the mechanisms that contribute to the delay of radio signals between satellites and receivers. The dissertation then focuses on software developed at the Hartebeesthoek Radio Astronomy Observatory's (HartRAO's) Space Geodesy Programme to estimate tropospheric delays (from which PWV is calculated) in near real-time. In addition an application of this technique, namely the improvement of tropospheric delay models used to process satellite laser ranging (SLR) data, is investigated. The dissertation concludes with a discussion of opportunities for future work. / Thesis (M.Sc. (Physics))--North-West University, Potchefstroom Campus, 2004.