This thesis describes an investigation of, and improvements to, the microphysical modelling of aerosols in the Oxford-Rutherford Appleton Laboratory Aerosol and Clouds retrieval (ORAC), which is used to obtain aerosol properties from measurements by the Advanced Along Track Scanning Radiometer (AATSR). Modelling decisions determine the light scattering properties of the aerosol classes which in turn alter the retrieved aerosol properties: aerosol optical depth, and effective radius. The maritime, mineral dust, urban, and biomass burning aerosol classes were first investigated, and then improvements implemented. Major additions to the scheme include the ability to model non-spherical dust as spheroids, soot as fractal aggregates, and to coat spherical particles with an extra layer of differing refractive index (whose thickness can be modified by ambient relative humidity where necessary). Output from aerosol retrievals containing these new models is presented. Modelling of marine aerosol was found to be adequate, but an improvement in the relative humidity assumptions led to an average 5 % increase in aerosol optical depth (AOD). Modelling of mineral dust aerosols has been dramatically altered by the addition of non-spherical dust and hygroscopic particles, leading to increases in measured AOD of over 100 % during dust events, compared to the previous model. Measurement of biomass burning aerosol has been tested with an `ageing' aerosol scheme, leading to increases in over-land measured AOD of 0.14 (~50 % increase). With such significant changes in AOD, representation of aerosol light scattering properties is seen to be important factor in the accuracy of the ORAC scheme. Finally, a method of optimising the placement of detectors in an aerosol measurement device is presented.

Aerosol particles, especially in the high Arctic are still not very well represented in climate models. Particle size and number concentrations are strongly under-predicted and temporal variations of aerosol composition and size are still not very well understood, mainly due to the sparsity of observations. The main objective of this thesis is the characterization of the high Arctic summer aerosol by means of electron microscopy in order to extend the existing data set from previous expeditions by size resolved data on aerosol number, morphology and chemical composition and to gain a better understanding of the evolution of the aerosol in the atmosphere. Ambient aerosol was collected over the pack ice during the Arctic Summer Cloud and Ocean (ASCOS) campaign to the high Arctic in summer 2008. Aerosol particles were evaluated with scanning electron microscopy and subsequent digital image processing to assess particle size and morphology. More than 3900 aerosol particles from 9 sampling events were imaged with scanning electron microscopy and merged into groups of similar morphology which contributed to different degrees to the total aerosol: single particles (82%), gel particles (11%) and halo particles (7%). Single particles were observed over the whole size range with a maximum at 64 nm in diameter, gel particles appeared &gt; 45 nm with a maximum in number at 174 nm, halo particles appeared &gt; 75 nm with a maximum in number at 161 nm. The majority of particles showed the morphology of marine gels, no sea salt or otherwise crystalline particles were observed. Transmission electron microscopy enabled more subtle insights into particle morphology and allowed further subdivision of gel particles into aggregates, aggregates with film and mucus-like particles. Energy dispersive X-ray spectroscopy of individual particles revealed a gradual transition in the content of Na+/K+ and Ca2+/Mg2+ between particle morphologies. Single particles and aggregate particles preferentially contained Na+/K+ whereas aggregate with film particles and mucus-like particles mainly contained Ca2+/Mg2+ suggesting a connection between particle morphology and ion content. Back-trajectory analysis was used to identify aerosol sources and to understand the evolution of the aerosol as a function of the synoptic weather situation. Particle numbers, size and morphology changed with the days the air mass spent over the pack-ice. A morphological descriptor applied to gel particles showed a clear trend suggesting that the contour of the particles becomes sharper and more distinct with increased time spent over the pack-ice. For a very long time over the pack-ice, however, we observed a morphology comparable to freshly emitted particles suggesting aerosol sources over the inner pack-ice. Size resolved aerosol chemical composition measurements were utilized to investigate the inorganic composition of laboratory generated nascent sea spray aerosol particles and ambient aerosol samples collected during ASCOS. A significant enrichment of Ca2+ was observed in submicrometer particles in either case with a tendency for increasing Ca2+ enrichment with decreasing particle size. This has strong implications for the alkalinity of sea spray aerosol particles with consequences for the sulfur chemistry in the marine boundary layer, the hygroscopicity and thus the potential of sea spray aerosol particles to act as cloud condensation nuclei. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.</p>

Organic aerosol (OA) is a ubiquitous component of atmospheric particulate that influences both human health and global climate. A large fraction of OA is secondary in nature (SOA), being produced by oxidation of volatile organic compounds (VOCs) emitted by biogenic and anthropogenic sources. Despite the integral role of SOA in atmospheric processes, there remains a limited scientific understanding of the chemical and physical changes induced in SOA as it ages in the atmosphere. This thesis describes work done to increase the knowledge of processes and properties of atmospherically relevant SOA. In the work presented in this thesis, I have worked on improving an existing innovative, soft ionization aerosol mass spectrometer and utilized it to establish chemical mechanisms for oxidation of atmospherically relevant organic precursors (i.e., Green Leaf Volatiles). I discovered that SOA formation from cis-3-hexen-1-ol is dominated by oligomer and higher molecular weight products, whereas the acetate functionality in cis-3-hexenylacetate inhibited oligomer formation, resulting in SOA that is dominated by low molecular weight products. One of the most important factors contributing to uncertainties in our estimations of SOA mass in the atmosphere, remains our basic assumption that atmospheric SOA is liquid-like, which we have found to be untrue. Hence, I developed a methodology to estimate the phase state of SOA and identified new parameters that can have significant influence on the phase state of atmospheric aerosol. This simplified method eliminates the need for a Scanning Mobility Particle Sizer (SMPS) and directly measures Bounce Factor (BF) of polydisperse SOA using only one multi-stage cascade Electrostatic Low Pressure Impactor (ELPI). The novel method allows for the real time determination of SOA phase state, permitting studies of the relationship between SOA phase, oxidative formation and chemical aging in the atmosphere. I demonstrated that SOA mass loading (CSOA) influences the phase state significantly. Results show that under nominally identical conditions, the maximum BF decreases by approximately 30% at higher CSOA and suggests that extrapolation of experiments not conducted at atmospherically relevant SOA levels to simulate the chemical properties may not yield results that are relevant to our natural environment. My work has provided a better understanding of the mechanisms of aerosol formation at atmospheric concentrations, which is necessary to understand its physical properties. This improved understanding is fundamental to accurately model aerosol formation in the atmosphere, and subsequently evaluate their large-scale effect on human health and environment.

Approved for public release, distribution is unlimited / This thesis assesses the performance of the Naval Postgraduate School Aerosol Optical Depth (NPS AOD) model utilizing very high spatial resolution QuickBird (QB) satellite data. QuickBird derived AOD results are compared to other satellite and ground based AOD results, specifically, AErosol RObotic NETwork (AERONET), MODerate resolution Imaging Spectroradiometer (MODIS), Multi-angle Imaging SpectroRadiometer (MISR), and Advanced Very High Resolution Radiometer (AVHRR). Data is collected around Sir Bu Nuair Island, United Arab Emirates in September 2004 as part of the UAE2 Campaign. Satellite measured radiances are calibrated and due to spatial resolution differences between sensors, modal radiances are calculated for areas matching the highest resolution sensor. The AOD model is based on AVHRR wavelengths; hence, the modal satellite measured radiances are linearly extrapolated to the effective wavelengths of AVHRR. Results show application of the NPS AOD model to QuickBird data yields findings that are consistent with other satellite and ground based retrievals. In general, the NPS AOD model works well for nadir and near-nadir view angles, but not for high zenith angles. / Lieutenant Commander, United States Navy

Doctor of Philosophy / Department of Entomology / James F. Campbell / Kun Yan Zhu / Aerosol applications of reduced risk insecticides such as synergized pyrethrin and insect growth regulators (IGR) are part of food industry integrated pest management programs. Since aerosols cannot penetrate into hidden areas exploited by pests such as the red flour beetle, Tribolium castaneum, the potential for these insecticides to effect beetle populations was evaluated. Because IGRs do not cause immediate mortality, the potential of horizontal transfer for an IGR from treated to untreated individuals was also examined. Results showed that when untreated T. castaneum, larvae or pupae, were added to flour containing methoprene, IGR, treated larvae, pupae or adults, the untreated individuals exhibited evidence of methoprene exposure (external deformities and reduced survival). Evaluation of the different mechanisms of transfer indicated that contact with methoprene treated individuals or flour that had been in contact with treated individuals may be the primary method of methoprene transfer. Since aerosols are often applied as a combination of IGR and pyrethrin with a carrier, the effect of these components was evaluated. Applications of synergized pyrethrin caused knockdown of adults but affected adults recovered and progeny production was not effected. Exposure of eggs to these insecticides reduced egg hatch. Food material accumulations inside food facilities can potentially increase or reduce insecticide efficacy. Evaluation of different flour residue levels, representing different sanitation levels, revealed that sanitation alone reduced immature development. As flour residue depths increased more individuals developed into adults but very few developed in the insecticide treatments. Food facilities that use aerosol insecticides apply them at regular intervals, so the cumulative effects of these treatments were considered. Experiments evaluating repeated insecticide exposures indicated that the direct morality from synergized pyrethrin not the horizontal transfer of methoprene was the primary factor in population reduction. Overall findings suggested that methoprene is highly mobile between different surfaces. Exposure of untreated individual beetle larvae to treated larvae or pupae or to flour that has been in contact with exposed beetles can have detrimental effects on development or survival, but these effects may be highly variable and even in cumulative exposures the overall level of population suppression is limited.

MSc., Faculty of Science, University of the Witwatersrand, 2011 / Atmospheric aerosols have direct and indirect impacts on the earth’s radiation budget and the radiative forcing on the climate system. A large uncertainty exists regarding aerosols and the effect they have on the earth’s radiation budget and global change. The distribution, concentration and types of aerosols are therefore of great importance regarding global warming and climate change. The purpose of this study is to present the atmospheric aerosol characteristics found over the South Atlantic, Southern Ocean and Antarctic continent as well as identify their origin. The aerosol optical properties over the South Atlantic and Southern Ocean region is analysed during the South African National Antarctic Expedition 2007/2008 (SANAE 47) take over cruise on board the M/V S.A. Agulhas. Very low aerosol optical thickness (AOT) values were obtained for the Antarctic Coastal region with a mean AOT500nm of 0.03 and a mean Angstrom exponent of 1.78. The South Atlantic region showed a mean AOT500nm of 0.06 and a mean Angstrom exponent of 0.72. AOT values for the South African coastal region had a mean AOT500nm of 0.07 and a mean Angstrom exponent of 0.76. Data comparisons confirm that the data acquired during the study are consistent with previous research from the study region. Comparisons were made between the dataset and the MODIS satellite aerosol product. A discrepancy was shown to exist between the MODIS aerosol product and the acquired dataset using the Microtops II Sunphotometer. Both MODIS TERRA and AQUA overestimate AOT at 550nm.

Cette thèse s’inscrit dans le projet OxHelease (ANR-TecSan 2011) qui vise à étudier l’impact de l’inhalation de l’hélium-oxygène sur la ventilation, l’oxygénation sanguine, le dépôt d’aérosol dans l’asthme et l’emphysème. Dans ce cadre, ce travail de thèse a consisté à mettre au point des méthodes d’imagerie par résonance magnétique pour quantifier les dépôts d’aérosols chez le rat. L’administration de médicaments par voie inhalée est une approche possible pour le traitement des maladies pulmonaires comme les broncho-pneumopathies chroniques obstructives. C’est également une voie intéressante pour l’administration systémique de médicaments en raison d’un transfert potentiellement rapide dans le sang. Néanmoins, le transport et les dépôts de particules dans les poumons sont complexes et difficiles à prédire, à cause de la dépendance de nombreux paramètres, tels que le protocole d’administration, la morphologie des voies aériennes, le profil respiratoire, ou encore les propriétés aérodynamiques du gaz et des particules. Pour mieux maîtriser cette voie d’administration de médicaments, des outils d’imagerie peuvent être utilisés. L’IRM est moins conventionnelle que d’autres approches pour caractériser le poumon, mais les progrès techniques et les multiples mécanismes de contraste exploitables peuvent être mis à profit pour ce faire.Pour obtenir un signal exploitable du parenchyme pulmonaire chez le rat, une séquence IRM à temps d’écho court a été mise en place sur un système clinique à 1,5 T. Cette technique a été combinée à une administration de courte durée d’un aérosol de chélate de Gadolinium en respiration spontanée. Le mécanisme de contraste principal utilisé est la modification du temps de relaxation longitudinale induisant un rehaussement du signal et qui permet d’estimer la concentration locale avec une résolution spatiale de (0,5 mm)3 et temporelle de 7,5 min permettant également de suivre l’élimination pulmonaire au cours du temps. La sensibilité de cette approche (seuil de détection de l’ordre de 20 µM) a été déterminée et pour cela des méthodes d’analyses spécifiques globales et locales incluant des segmentations, des analyses de distributions et des statistiques ont été développées. Après validation sur des rats sains, pour lesquels un rehaussement moyen de 50%, une distribution homogène de dépôt et une dose totale relativement faible (~1 µmol/kg de poids corporel) ont été observés, cette modalité d’imagerie a pu être appliquée chez des modèles asthmatiques et emphysémateux qui ont montrés des différences significatives de certains paramètres comme l’homogénéité des dépôts ou la cinétique d’élimination. Par ailleurs, des résultats préliminaires de mise en place d’une étude multimodale, où l’IRM est comparée à la tomodensitométrie et à l’imagerie nucléaire sur les mêmes animaux a été effectuée. Enfin, dans une optique d’évaluation de la faisabilité d’approches quantitatives par IRM, un système double noyaux proton-fluor pour déterminer la sensibilité de l’imagerie de gaz et d’aérosols fluorés a été implémenté et testé sur des rats.Ces approches par IRM ouvrent des perspectives pour permettre la caractérisation in vivo des dépôts de particules inhalées dans des conditions d’administration variées et leur sensibilité suggère un transfert potentiel chez l’homme / This PhD thesis is part of the OxHelease project (ANR-TecSan 2011) that aims to study the impact of helium-oxygen inhalation on ventilation, blood oxygenation, and aerosol deposition in chronic obstructive respiratory diseases, such as asthma and emphysema. In this context, this work consisted of developing magnetic resonance imaging methods to quantify aerosol deposition in rat lung.The inhalation of pharmaceutical aerosols is an attractive approach for the treatment of lung diseases such as chronic obstructive pulmonary diseases. This is also an interesting route for the treatment of systemic disorders with the potentially fast drug transfer into circulation. However, the transport and the deposition of particles within the lungs are complex and difficult to predict, since deposition patterns depend on a number of parameters, such as administration protocols, airway geometries, inhalation patterns, and gas and aerosol aerodynamic properties. Thus, understanding drug delivery through the lungs requires imaging methods to quantify particle deposition. MRI is less conventional than other approaches for lung characterization, but the technical advances and the multiple contrast mechanisms render lung imaging more feasible.To obtain exploitable signal from the lung parenchyma of the rat, an ultra-short echo (UTE) sequence was implemented on a 1.5 T clinical system. This technique was combined with a Gadolinium-based aerosol nebulization of short duration in spontaneously breathing rats. The main contrast mechanism used here is the modification of the longitudinal relaxation time yielding signal enhancement and allowing to assess the local concentration with a spatial resolution of (0.5 mm)3 and a temporal resolution of 7.5 min enabling to quantitatively follow up lung clearance. The sensitivity of this approach (with a detection limit close to 20 µM) was determined. To do so several specific processing methods were developed for local and total lung evaluation, including segmentation, distribution analysis and statistics. After validation in the healthy rats, for which a signal enhancement of 50% on average, a homogenous distribution of deposition and a relatively low total deposited dose (~1 µmol/kg body weight) were observed, this imaging modality could be applied in asthmatic and emphysematous animal models. Significant differences were obtained such as homogeneity of deposition or clearance. Moreover, preliminary results of a multimodal study, in which MRI was compared with computed tomography and with nuclear medicine imaging in the same animals, were obtained. Finally, in order to evaluate the feasibility of other potential quantitative MRI approaches, a dual-nuclei proton/fluorine system was implemented and tested in rats for determining the sensitivity of fluorine-based gas and aerosol imaging.These MRI strategies may be applied for the in vivo characterization of particle deposition inhaled under variable administration conditions. Their sensitivity suggests a feasible translation to human.

Aerosol particles are one of the major pollutants in outdoor and indoor air. Particulate matter (PM) can be harmful for works of art by causing soiling and chemical damage, depending on particle size and chemical composition. This study includes indoor/outdoor monitoring of air quality in five archives in the CR, representing different outdoor environments: Zlatá Koruna (rural), Třeboň (small town), Teplice (industrial area), and two archives (National Library - NL and National Archives - NA) in Prague (large city with traffic). The NL and the archives in Zlatá Koruna, Třeboň and Teplice are only naturally ventilated, while NA in Prague is equipped with ventilation and filtration system. The measurements were performed during 4 intensive campaigns in different seasons of the year at every location. The measurements included particle number/mass concentrations, size distributions and chemical composition. Additional measurements were carried out in 2 museums, a depository, and a church. The aim of this study is to investigate concentrations, sources, and chemical composition of PM in the indoor environment, and to establish the relationship between the indoor and outdoor environment. The results showed that concentrations of fine particles in the indoor environment of the NA in Prague were...

A emissão de poluentes em megacidades e áreas industriais pode ter fortes impactos no clima e na saúde. Nos últimos anos tem sido crescente a preocupação com emissões atmosféricas contendo partículas nanométricas, cuja presença, juntamente com compostos orgânicos voláteis, óxidos de nitrogênio e outros, pode resultar na formação de uma série de substâncias gasosas poluentes e na formação de aerossóis. Medições mais precisas da concentração e distribuição de tamanho de fuligem são importantes, não só do ponto de vista ambiental, mas também para a saúde humana. O objetivo deste trabalho foi determinar a distribuição de tamanho de partículas na chaminé de uma refinaria em Cubatão. Para isso foi utilizada uma abordagem baseada nos métodos de inversão, tradicionalmente usados para calcular parâmetros de aerossóis atmosféricos, ao contexto dos aerossóis de tochas industriais. Os resultados se mostraram consistentes com a literatura científica, sendo possível determinar alguns parâmetros da distribuição do tamanho de partículas provenientes da chama de uma tocha industrial utilizando um sistema lidar de três comprimentos de onda com um nível de discrepância aceitável. Um estudo do expoente de Angström foi realizado com o objetivo de validar o algoritmo de inversão desenvolvido neste trabalho. Os resultados deste estudo mostraram que os dados experimentais corroboram com as curvas teóricas e, portanto, o algoritmo pode ser utilizado como ferramenta para a medição de emissões atmosféricas provenientes de tochas industriais. O desenvolvimento deste projeto representará um passo importante, não somente do ponto de vista tecnológico, mas principalmente como recurso para tratar de problemas de emissões que futuramente poderão surgir, dentre as medidas voltadas ao controle de mudanças climáticas. / The emission of pollutants in megacities and industrial areas can have strong impacts on climate and health. In recent years there has been a growing concern about air emissions containing nanometric particles whose presence, together with volatile organic compounds, nitrogen oxides, and others, can result in the formation of a series of gaseous pollutants and aerosol. More accurate measurements of the concentration and size distribution of soot are important not only from an environmental point of view, but also to human health. The objective of this study was to determine the particle size distribution in the chimney of a refinery in Cubatao. For this it used an approach based on inversion methods traditionally used to calculate parameters of atmospheric aerosols, the context of aerosols of industrial torches. The results were consistent with the scientific literature, it is possible to determine some parameters of size distribution of particles from an industrial torch flame using a system handling three wavelengths with an acceptable level of mismatch. A study by the Angstrom exponent was carried out in order to validate the inversion algorithm developed in this work. The results of this study showed that corroborate experimental data with the theoretical curves and thus the algorithm can be used as a tool for measuring atmospheric emissions from industrial torches. The development of this project will be an important step, not only from a technological point of view, but rather as a resource to address emission problems that may arise in the future, among the measures aimed at controlling climate change.

O sistema climático terrestre é regido pela interação entre o fluxo de radiação solar e diversos elementos presentes na atmosfera e na superfície. Entre esses elementos destacamos o papel que as nuvens desempenham nesse processo devido a sua elevada cobertura terrestre, que chega a média de três quartos de todo o globo. Do total de radiação solar que atinge a atmosfera, as nuvens são responsáveis pela reflexão direta de cerca de 23% da radiação incidente de volta ao espaço evitando, assim, o aquecimento da superfície. Por outro lado, parte da radiação térmica emitida pelo solo é absorvida e reemitida pelas nuvens podendo ocasionar em um aumento de temperatura próximo à superfície dependendo da sua altitude. Todo esse processo está intimamente relacionado a quantidade de nuvens, sua espessura óptica e o comprimento de onda da radiação, podendo a resposta do sistema variar conforme muda-se alguma dessas condições. Outro elemento que influencia tanto nas características das nuvens quanto no balanço radiativo terrestre é o aerossol atmosférico. Sua presença na atmosfera pode tanto aumentar a temperatura em solo quanto diminuí-la, dependendo do tipo de aerossol, sua quantidade, distribuição espacial e da radiação com a qual está interagindo. Ele também participa na formação das nuvens ao atuar como núcleo condensador de nuvens em atmosfera supersaturada, facilitando a aglutinação de vapor de água em torno de si. A presença de elevadas quantidades de aerossóis para uma determinada taxa de umidade do ar, dificulta a formação e o desenvolvimento vertical da nuvem, podendo até mesmo acarretar sua evaporação. Como a variabilidade dos aerossóis na atmosfera, em geral, é muito alta e devido a sua interação com a radiação variar com o comprimento de onda, a determinação precisa do seu efeito no balanço radiativo terrestre é prejudicada. Esses processos citados evidenciam a enorme complexidade no entendimento das relações envolvendo esses dois elementos presentes na atmosfera terrestre. Para diminuir essa lacuna, sobrevoamos uma região próxima a Porto Velho (RO) entre os dias 21 e 28 de setembro de 2012 munidos de um aparato experimental a fim de analisar o perfil vertical das nuvens. Esse aparato continha uma câmera sensível a comprimentos de onda visíveis (aproximadamente de 440nm a 700nm), uma câmera térmica, sensível a comprimentos de onda entre 8 e 14m, e outra sensível a comprimentos de onda no infravermelho próximo, entre 900nm e 2500nm. Esse conjunto de instrumentos permitiu obter medidas da radiação emergente da lateral de nuvens convectivas na região estudada. / none