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 29 for “"Cloud Condensation Nuclei"”.
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Cloud condensation nuclei in western Colorado: observations and model predictions
Variations in the warm cloud‐active portion of atmospheric aerosols, or cloud condensation nuclei (CCN), have been shown to impact cloud droplet number concentration and subsequently cloud and precipitation processes. This issue carries special significance in western Colorado where a significant …
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Hygroscopic growth and cloud condensation nuclei activity of fresh and chemically-aged biomass-pyrolyzed organic aerosol
… prominent contributors of organic aerosols and cloud condensation nuclei (CCN) in the atmosphere. Aerosol-cloud interactions contribute to uncertainties in estimates of climate forcing, not only because of the complexities in their initial size and chemical composition, but also because of …
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Sub-grid process analysis of the sensitivity of black carbon aging to particle microphysical properties at emission
… altering their radiative properties and cloud condensation nuclei activity. Understanding these aging processes is essential in assessing black carbon’s direct and indirect climate forcing. The initial black carbon becomes a complex distribution of distinct multi-component particles, …
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Cloud condensation nucleus activity comparison of dry- and wet-generated mineral dust aerosol : the significance of soluble material
… vapor to determine the conditions required for cloud droplet formation. Droplet formation conditions are investigated for two common clay minerals, illite and sodium-rich montmorillonite, and an industrially derived sample, Arizona Test Dust. Using wet and dry particle generation coupled to a …
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Improving model representations of black carbon using a particle-resolved aerosol model
… absorbing solar radiation, by interacting with clouds, and by decreasing the albedo of ice and snow. Each of these climate effects depends on the properties of individual BC-containing particles and their atmospheric residence time. The dominant removal mechanism of BC mass from the atmosphere …
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Atmospheric organic aerosol - water interactions
… they can also indirectly affect by serving as cloud condensation nuclei (CCN). While the chemistry and physical properties of the inorganic components of the aerosols are more or less known, the same does not stand for the organic components. Hygroscopic water soluble organic material can …
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An ensemble modeling approach to examining the impact of the Saharan air layer on the evolution of an idealized tropical cyclone
… is whether TC evolution depends on increases in cloud condensation nuclei, thought to occur in the SAL, in a predictable manner. In this study, the Regional Atmospheric Modeling System (RAMS) was used to test if a systematic dependence of the evolution of TC intensity on cloud condensation nuclei …
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Investigating the impacts of entrainment on nucleation scavenging of black carbon particles through particle-resolved simulations
… to a positive radiative forcing. The optical and cloud condensation nuclei properties of the aerosol depend on the per-particle chemical species composition, or mixing state. Challenges arise in determining black carbon climate effects because the mixing state changes during the particles’ …
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Surfactant Behavior in Atmospheric Aerosols
… in the Earth climate system due to their role in cloud formation and the global radiation budget. However, there are still many unanswered questions about how the composition of the aerosol varies and how this composition affects the climate system. While aerosols contain a mix of organic and …
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Quantification of Airborne Fungal Spores Comparing Molecular Tracers via Ion Chromatography and UV-LIF Methods
… also have been shown to act as effective ice nuclei and giant cloud condensation nuclei in some cases. This has implications on the hydrological cycle on local and regional scales by impacting the formation and evolution of clouds and precipitation. The quantification of fungal spores has been …
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Role of Water in the Formation, Transformation and Fate of Secondary Organic Aerosol
… in SOA formation, chemical aging and fate as cloud condensation nuclei. The formation of SOA from the photooxidation of isoprene in the presence of various sulfate seed particles was investigated using a flow tube reactor. Under constant environmental conditions, particle-phase water was found …
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Studies towards assessing the effects of aviation on climate
… affect the amount and characteristics of cirrus clouds. Soot and sulfate particles can also change the cloudiness by acting as cloud condensation nuclei. Due to the high growth in air traffic that is projected to continue, it is important to understand the effects of aviation on air quality and …
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Investigation into the mechanisms of size-resolved particle dry deposition across three environments
… light - and indirect effects- acting as cloud condensation nuclei and altering the lifetime of clouds. The magnitude of these effects is largely determined by particle lifetime, which is defined by their rate of removal through wet and dry deposition. Dry deposition, specifically of …
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Simulating and quantifying land-surface biogeochemical, hydrological, and biogeophysical processes using the Community Land Model version 4
… surface radiation/energy balance, and may act as cloud condensation nuclei to modify precipitation rates and eventually the hydrological cycle. Therefore, we were motivated to investigate these processes in different ecosystems. Specifically, this research aims to 1) to elucidate the carbon- and …
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Fluorescent Biological Aerosol Particles in Coastal Canada and the Link to Atmospheric Ice Nuclei
… of the global climate through their role as nuclei for cloud droplet formation. Several types of biological organisms (e.g., fungi and bacteria) have been shown to be effective ice nuclei (IN) and cloud condensation nuclei (CCN).</p> <p>During 21 days in August 2013 we participated in a …
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Simulating the sources of organic aerosol in the atmosphere
… they can reduce the visibility and they act as cloud condensation nuclei. Through the absorption and the scattering they can have a big influence on the energy balance of the planet. The organic components of particulate matter contribute more than 50% to their total mass. Organic aerosols (OA) …
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Particle-resolved modeling for evaluating assumptions in aerosol studies
… of the size distribution, gas partitioning, and cloud condensation nuclei (CCN) concentrations. The objective of my study is to assess the interactions between the coarse mode with other particle size ranges and determine the conditions where it is acceptable to treat the coarse mode as …
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Particle-resolved aerosol modeling on the regional scale – insights into importance of capturing aerosol mixing state
… solar radiation, and indirectly by forming clouds. These macroscale climate effects depend on the size and composition of individual particles. Simulating the evolution of aerosols and predicting their impacts remains a challenge due to the multiscale nature of the system. Various methods …
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Idealized particle-resolved large-eddy simulations to evaluate the impact of emissions spatial heterogeneity on CCN activity
Aerosol-cloud interactions remain a large source of uncertainty in climate models due to complex, nonlinear processes that alter aerosol properties and the inability to represent the full compositional complexity of aerosol populations within large-scale modeling frameworks. The spatial resolution …
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Development, uncertainty quantification, and reduction of a dimethyl sulfide oxidation mechanism
… acid and sulfuric acid, can contribute to cloud condensation nuclei. Studying the oxidation mechanism of DMS will help improve our modelling of the natural processes that contribute to the Earth's radiative balance. In the past decade, the discovery of a major new pathway in DMS oxidation …
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