Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 20 for “"tropospheric chemistry"”.
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Modelling Climate Changes, Biogenic Emissions and Tropospheric Chemistry in Southeast Asia.
… forcing. Consequently, a tropsopheric chemistry model (CiTTyCAT) was used to investigate the relative impact of climate changes and biogenic emissions on tropospheric chemistry, particularly ozone in both seasons and climate scenarios. A warming across the region occurred, with the …
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An investigation into the tropospheric chemistry of acidic aerosols and ammonia in the laboratory
… presented here are original to the field of tropospheric chemistry. SHO3-; S2O52-; HSO4-; SO42- and H1,3,5C2,3,4O4-;C2,3,4O4 2- were the main components found in the complex inorganic-organic systems investigated here. The introduction of ammonia produced ammonium dicarboxylate as well as …
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Development and Evaluation of a Comprehensive Tropospheric Chemistry Model for Regional and Global Applications
… impact of anthropogenic emissions must employ a tropospheric chemistry model that predicts realistic distributions of aerosols of all types. The need for a such a comprehensive yet computationally efficient tropospheric chemistry model is addressed in this research via systematic development of …
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Sensitivity of tropospheric chemistry to the source of NO x from lightning : sensitivity simulations with the global 3D chemistry model for atmospheric transport and chemistry MATCH-MPIC
… nitrogen oxides is studied using the global chemistry transport model MATCH-MPIC. The responses of NOx, O3, OH, HNO3 and peroxyacetyl-nitrate (PAN) are investigated. A marked sensitivity to both parameters is found. NOx burdens globally can be enhanced up to 100% depending on the vertical …
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Interactions of the Terrestrial Biosphere With Climate and Atmospheric Chemistry
… have been shown to significantly impact global tropospheric chemistry and composition, climate and the global carbon cycle. In the second part of this dissertation, the sensitivity of biogenic isoprene and monoterpene emissions to combined and isolated fluctuations in observed climate and …
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Biofuels & atmospheric chemistry: what can a global model tell us about our future decisions?
… scale biofuel use could have on atmospheric chemistry. I review the current state of biofuels politically and technologically, focusing on ethanol and biodiesel. I discuss the salient features of tropospheric chemistry and in particular the oxidation of isoprene, an important biogenic …
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Modeling of an upper Midwest forest boundary layer and vehicle indoor air quality
<p>The key to understanding tropospheric chemistry begins with the hydroxyl and hydroperoxy radicals. Recent research suggests that there is still considerable uncertainty in our understanding of the sources of these radicals and their role as sinks. The work detailed in this thesis describes a …
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A study of the tropospheric oxidation of volatile organic compounds using chemical ionization mass spectrometry
… spectrometer. The ability to accurately model tropospheric chemistry depends on kinetic and mechanistic information for a wide variety of species. The gas-phase chemistry of the troposphere is dominated by the oxidation of trace species such as methane. One important intermediate in the …
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Direct and Indirect Effects of Elevated Carbon Dioxide and Ozone on the Canopy of a Soybean Agroecosystem
… removal of leaf area, and the changes in leaf chemistry in elevated [CO2] and [O3] may lead to increased herbivory. These predictions were tested using Soy bean F&barbelow;ree-A&barbelow;ir C&barbelow;oncentration E&barbelow;nrichment technology (SoyFACE) with plots exposed to ambient air …
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Turbulent Exchange of Ozone and Nitrogen Oxides between an Amazonian Rain Forest and the Atmosphere
… nitrogen oxides, which are of high relevance for tropospheric chemistry. To asses the effect of land use change on tropospheric chemistry, a good knowledge of the exchange of those trace gases between the primary rain forest ecosystem and the atmosphere is necessary. So far, experimental …
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Applications of Adjoint Modelling in Chemical Composition: Studies of Tropospheric Ozone at Middle and High Northern Latitudes
Ozone is integral to tropospheric chemistry, and understanding the processes controlling its distribution is important in climate and air pollution contexts. The GEOS-Chem global chemical transport model and its adjoint are used to interpret the impacts of midlatitude precursor emissions and …
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Formation of Nitrous Acid on Urban Surfaces
… a significant source of OH-radicals, which drive tropospheric chemistry and ozone-formation. Recently, unexpected high values of HONO have been detected during the day. Despite its importance, sources of HONO are still poorly understood. Direct emission of HONO or homogeneous chemical formation …
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The Changing Role of Reactive Nitrogen in the Troposphere
… Nitrogen oxides play a central role in driving tropospheric chemistry and are a key ingredient of fine particulate matter, acid rain, and ozone. However, despite this long-understood importance of reactive oxidized nitrogen (NOy) species, even modern chemical transport models have struggled to …
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Novel Methods to Characterise Atmospherically Relevant Organic Radicals and Reactive Oxygen Species
… intermediates represent a large uncertainty in tropospheric chemistry, and pose an analytical challenge due to their high reactivity and typically low concentrations. This emphasises the need for the development of new methods to characterise the chemistry of these species. In this thesis, …
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Optical properties of light absorbing organic carbon aerosol and its mixtures at high sub-saturated humidities
… for semi-direct and indirect climate effects and tropospheric chemistry.
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Remote Sensing of the Lower Atmosphere: From Surface Concentration to Mixing Layer Height
… products include near surface concentration, tropospheric column and vertical profile for different trace gases. It addresses an important gap in near surface air quality measurements that is difficult for in-situ, satellite and other remote sensing measurements to address. Different …
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Long term trends of halogenated trace gases, hydrocarbons, alkyl nitrates and of the oxidative capacity of the atmosphere
… Tasmania. A two-dimensional global atmospheric chemistry transport model is used to derive global annual emission histories of these long lived gases. Emissions of the halons are found to have decreased since peaking in the 1990s. There is still some considerable uncertainty in the remaining …
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Improvements to our Understanding of Toronto-area Atmospheric Composition
… events (defined as enhanced O3 or CO lower-tropospheric (0-5 km) columns that coincided with surface O3 exceedances) were found in the TAO dataset between 2002 and 2010. O3 columns over Toronto during pollution events are influenced by urban and industrial anthropogenic NOx emissions, …
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Optimal determination of global tropospheric OH concentrations using multiple trace gases
… hydroxyl radical (OH) plays a decisive role in tropospheric chemistry. Reactions with OH provide the dominant path of removal for a variety of greenhouse gases and trace species that contribute to the destruction of the ozone layer. Accurate determination of global tropospheric OH concentrations …