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Full-Text Articles in Engineering

Nineteenth Century North American And Pacific Tidal Data: Lost Or Just Forgotten?, Stefan A. Talke, David A. Jay Nov 2013

Nineteenth Century North American And Pacific Tidal Data: Lost Or Just Forgotten?, Stefan A. Talke, David A. Jay

Civil and Environmental Engineering Faculty Publications and Presentations

Tide data are the oldest and longest oceanographic records and comprise one of the few tools for understanding, quantifying, and separating century-scale human and climate impacts on the coastal zone. Our archival research indicates that continuous measurements of tides began in 1844 in the western Atlantic, 1853 in the Eastern Pacific, and 1858 in the Western Pacific. At least 50 multiyear tide series existed by the year 1900. With few exceptions, however, these 19th and early 20th century measurements have not been analyzed in more than a century and have been forgotten and neglected by the scientific community. This article …


Characterization Of Secondary Organic Aerosol Precursors Using Two-Dimensional Gas Chromatography With Time Of Flight Mass Spectrometry (Gc×Gc/Tofms), Melissa Jordan Roskamp Sep 2013

Characterization Of Secondary Organic Aerosol Precursors Using Two-Dimensional Gas Chromatography With Time Of Flight Mass Spectrometry (Gc×Gc/Tofms), Melissa Jordan Roskamp

Dissertations and Theses

The oxidation of volatile organic compounds (VOCs) plays a role in both regional and global air quality through the formation of secondary organic aerosols (SOA). More than 1000TgC/yr of non-methane VOCs are emitted from biogenic sources (significantly greater than from anthropogenic sources). Despite this magnitude and potential importance for air quality, the body of knowledge around the identities, quantities and oxidation processes of these compounds is still incomplete (e.g., Goldstein & Galbally, 2007; Robinson et al., 2009). Two-dimensional gas chromatography paired with time-of-flight mass spectrometry (GC×GC/TOFMS) is a powerful analytical technique which is explored here for its role in better …


Incorporating Chemical Activity And Relative Humidity Effects In Regional Air Quality Modeling Of Organic Aerosol Formation, Marguerite Colasurdo Marks Aug 2013

Incorporating Chemical Activity And Relative Humidity Effects In Regional Air Quality Modeling Of Organic Aerosol Formation, Marguerite Colasurdo Marks

Dissertations and Theses

Atmospheric particulate matter is known to have significant effects on human health, visibility, and global climate. The magnitudes of these effects, however, depend in complex ways on chemical composition, relative humidity, temperature, phase state, and other parameters. Current regional air quality models such as CMAQ (Community Multiscale Air Quality model) ignore many of these considerations, and consider that the formation of secondary organic aerosol (SOA) can be calculated by assuming thermodynamic ideality in the organic particulate matter (OPM) phase as well as negligible uptake of water into the OPM phase. Theoretical predictions and model simulations considering non-ideality and water uptake …


Climate Change Impact On The Spatio-Temporal Variability Of Hydro-Climate Extremes, Mohammad Reza Najafi Jun 2013

Climate Change Impact On The Spatio-Temporal Variability Of Hydro-Climate Extremes, Mohammad Reza Najafi

Dissertations and Theses

The rising temperature of the earth due to climate change has shown to alter the variations of hydro-climate variables, including their intensities, frequencies and durations. Extreme events such as floods are, in particular, susceptible to any disturbances in climate cycles. As such it is important to provide policymakers with sufficient knowledge about the probable impacts of climate change on hydrologic extremes and most importantly on floods, which have the highest impacts on the societies. For this reason analysis of hydro-climate extremes is commonly performed using data at each site (or grid cell), however due to the limited number of extreme …


Effects Of Molecular Structure Of The Oxidation Products Of Reactive Atmospheric Hydrocarbons On The Formation Of Secondary Organic Particulate Matter, Including The Effects Of Water, Negar Niakan Jan 2013

Effects Of Molecular Structure Of The Oxidation Products Of Reactive Atmospheric Hydrocarbons On The Formation Of Secondary Organic Particulate Matter, Including The Effects Of Water, Negar Niakan

Dissertations and Theses

Organic aerosols have significant effects on human health, air quality and climate. Secondary organic aerosols (SOA) are produced by the oxidation of primary-volatile organic compounds (VOC). For example, α-pinene reacts with oxidants such as hydroxyl radical (OH), ozone (O3), and nitrate radical (NO3), accounting for a significant portion of total organic aerosol in the atmosphere. Experimental studies have shown that the oxidation process between α-pinene and ozone has the most significant impact in the formation of SOA (Hoffmann et al., 1997). Most of the models used to predict SOA formation, however, are limited in that they …


Analyzing Experimental Data And Model Parameters: Implications For Predictions Of Soa Using Chemical Transport Models, Kelley Barsanti, Annmarie G. Carlton, Serena H. Chung Jan 2013

Analyzing Experimental Data And Model Parameters: Implications For Predictions Of Soa Using Chemical Transport Models, Kelley Barsanti, Annmarie G. Carlton, Serena H. Chung

Civil and Environmental Engineering Faculty Publications and Presentations

Despite critical importance for air quality and climate predictions, accurate representation of secondary organic aerosol (SOA) formation remains elusive. An essential addition to the ongoing discussion of improving model predictions is an acknowledgement of the linkages between experimental conditions, parameter optimization and model output, as well as the linkage between empirically-derived partitioning parameters and the physicochemical properties of SOA they represent in models. In this work, a "best available" set of SOA modeling parameters is selected by comparing predicted SOA yields and mass concentrations with observed yields and mass concentrations from a comprehensive list of published smog chamber studies. Evaluated …