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Browsing by Author "Anderson, Georgiana Brooke, committee member"

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    Development and validation of an outdoor low-cost smoke monitor
    (Colorado State University. Libraries, 2017) Kelleher, Scott, author; Volckens, John, advisor; Jathar, Shantanu, committee member; Anderson, Georgiana Brooke, committee member; Pierce, Jeffrey, committee member
    Wildfires and prescribed fires produce emissions that are harmful to human health. These health effects, however, are difficult to quantify, likely in part due to sparse data on exposure. The ability to measure fire emissions as they reach sensitive areas is critical to ensuring the protection of public health. Ground level quantification of smoke from wildfires and prescribed fires has proven to be a difficult task. The state of the art for monitoring outdoor air quality has long relied upon expensive, cumbersome equipment that generally requires line power. Few ground-based measurements are typically made during fire events, which limits our ability to quantify and assess the impact of smoke from fire events. The objective of this work was to develop and validate a new type of outdoor air quality monitor, the Outdoor Aerosol Sampler (OAS). The OAS is an active, filter-based air sampler that has been miniaturized and weatherproofed. The OAS represents and attempt to address the technical limitations of field sampling with a device that is relatively inexpensive and independently powered. Prototype development of the OAS was made possible through low-cost electronics, open-source programming platforms, and in house fabrication methods. An online PM2.5 sensor was selected and integrated with the OAS. A Monte Carlo simulation aided in the selection of battery and solar power necessary to independently power the OAS, while keeping cost and size to a minimum. Cellular communications established via Short Message Service (SMS) technology were utilized in transmitting online sensor readings and controlling the OAS remotely. Numerous OAS were deployed to monitor smoke concentrations downwind from a large prescribed fire. Mass concentrations sampled from the burn were interpolated to depict smoke concentration gradients downwind of the fire. Field tests found OAS solar charging efficiency (6.7%) to be slightly less than model input efficiency (7.5%). Outdoor urban testing of the OAS demonstrates moderate agreement with equivalent federal reference method samplers for gravimetric analysis of PM2.5.
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    Effects of fuel moisture content on pollutant emissions from a rocket-elbow cookstove
    (Colorado State University. Libraries, 2018) van Zyl, Lizette, author; Volckens, John, advisor; Jathar, Shantanu, committee member; Anderson, Georgiana Brooke, committee member
    Cookstoves have been studied in recent decades for their health- and environment-relevant emissions. Many pollutants, stoves, and burning parameters have been investigated across these studies, including fuel moisture content, which is believed to have substantial impact on stove emissions. Yet, the effects of fuel moisture content on emissions remain poorly characterized. To address this gap in knowledge, this study characterized particle and gas-phase pollutant emissions during a laboratory experiment exploring three levels of fuel moisture from a single tree sample. Moisture levels tested here varied from 5% to 30% water content, by weight. A novel technique for re-moisturizing the fuel samples was developed and employed to expedite the experimental duration and to ensure consistency across tests. Results from the study demonstrate strong trends in emissions related to changes in moisture content. Results also suggest there are benefits to drying wood to below 10% moisture content as compared to burning wood that is slightly above the 20% level recommended by the U.S. Environmental Protection Agency. When wood was dried to 5% instead of 25%, modified combustion efficiency improved and average mass-based emissions factors decreased for all pollutant species (formaldehyde, acetaldehyde, benzene, toluene, ethylbenzene, m+p-xylenes, o-xylenes, PM2.5, methane, carbon monoxide, and organic carbon) save black carbon. Dry fuel generated less smoke and higher temperatures than wet fuel. Wet fuel was also difficult to keep lit and burned much slower than dry fuel. Efficiency, burn rate, and stove temperature all affect the way people use their stoves for heating or cooking. Since moisture content impacted efficiency, burn rate, and temperature during this study, as well as multiple gas and particle-phase pollutants, moisture content should be accounted for in future stoves studies, both in the lab and in the field.
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    Low-cost devices for occupational and environmental exposure assessment
    (Colorado State University. Libraries, 2018) Quinn, Casey, author; Volckens, John, advisor; Henry, Charles, advisor; Magzamen, Sheryl, committee member; Anderson, Georgiana Brooke, committee member; Reynolds, Stephen, committee member
    The measurement of chemical and physical stressors in occupational and environmental settings traditionally requires sophisticated equipment, trained professionals, and laboratory-based analyses. These requirements are cost and time prohibitive and, thus, limit the quantity and frequency of exposure monitoring. This dissertation focuses on the development of low-cost monitoring tools for evaluation of air and water quality. Water Quality Assessment Metal contamination of natural and drinking water systems poses hazards to public and environmental health. Quantifying metal concentrations in water typically requires sample collection in the field followed by expensive laboratory analysis that can take days to weeks to obtain results. The first portion of this was to develop a low-cost, field-deployable method to quantify trace levels of copper in drinking water by coupling solid-phase extraction/preconcentration with a microfluidic paper-based analytical device. This method has the advantages of being hand-powered (instrument-free) and using a simple 'read by eye' quantification motif (based on color distance). Tap water samples collected across Fort Collins, CO were tested with this method and validated against ICP-MS. We demonstrate the ability to quantify the copper content of tap-water within 30% of a reference technique at levels ranging from 20 to 500,000 ppb. The application of this technology, which should be sufficient as a rapid screening tool, can lead to faster, more cost-effective detection of soluble metals in water systems. Air Quality Assessment Personal monitors for air quality are expensive and cumbersome, which hinders epidemiologic and occupational exposure assessments. The Automated Microenvironmental Aerosol Sampler (AMAS) is a low-cost, wearable device containing four filter-pump assemblies designed to measure personal exposure particulate matter air pollution. This novel device collects size-selective samples of particulate matter from within distinct personal microenvironments (i.e. at home, at work, and in transit). The AMAS uses on-board sensors (GPS, light intensity, temperature, pressure, and acceleration) coupled with an algorithm (developed and described in to this work) to determine when an individual enters a given microenvironment and then initiates sampling through one of three filter assemblies. Low-cost devices capable of in-field quantification of pollutant hazards can allow researchers to afford more monitoring and analysis equipment and increase the size of epidemiology and industrial hygiene cohorts.
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    Quantifying and understanding current and future links between tropical convection and the large-scale circulation
    (Colorado State University. Libraries, 2020) Jenney, Andrea M., author; Randall, David A., advisor; Barnes, Elizabeth A., advisor; Maloney, Eric, committee member; Rasmussen, Kristen, committee member; Anderson, Georgiana Brooke, committee member
    Tropical deep convection plays an important role in the variability of the global circulation. The Madden Julian Oscillation (MJO) is a large tropical organized convective system that propagates eastward along the equator. It is a key contributor to weather predictability at extended time scales (10-40 days). For example, variability in the MJO is linked with variability in meteorological phenomena such as landfalling atmospheric rivers, tornado and hail activity over parts of North America, and extreme temperature and rainfall patterns across the Northern Hemisphere. Links between the MJO and atmospheric variability in remote locations are heavily studied. This is in part because the current skill of weather forecasts at extended time scales is mediocre, and because of evidence suggesting that the potential predictability offered by the MJO may not be fully captured in numerical prediction models. In the first part of this dissertation, I develop a tool for these types of studies. The "Sensitivity to the Remote Influence of Periodic Events" (STRIPES) index is a novel index that condenses the information obtained through composite analysis of variables after a periodic event (such as the MJO) into a single number, which includes information about the life cycle of the event, and for a range of lags with respect to each stage of the event. I apply the STRIPES index to surface observations and show that the MJO signal is detectable and significant at the level of individual weather stations over many parts of North America, and that the maximum strength of this signal exhibits regionality and seasonality. Tropical convection affects the extratropics primarily through the excitation of Rossby waves at the places where the upper-tropospheric divergent outflow associated with deep convection interacts with the background wind. In a future warmer climate, the strength of the mean circulation and convective mass flux is expected to weaken. A potential consequence is a weakening of Rossby wave excitation by tropical convective systems such as the MJO. In the second part of this study, I analyze a set of idealized simulations with specified surface warming and superparameterized convection and develop a framework to better understand why the mean circulation weakens with warming. I show that the decrease in the strength of the mean circulation can be explained by the slow rate at which atmospheric radiative cooling intensifies relative to the comparatively fast rate that the tropical dry static stability increases. I also show that despite a decrease in the mean convective mass flux, the warming tendency of the convective mass flux over the most deeply- convecting regions is not constrained to follow that of the global mean. In the final part of this dissertation, I consider how changes in the MJO and of the mean atmospheric state due to warming from increases in greenhouse gas concentrations may lead to changes in the MJO's impact over the North Pacific and North America. Specifically, I show that changes to the atmosphere's mean state dry static energy and winds have a larger impact on the MJO teleconnection than changes to MJO intensity and propagation characteristics.
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    Skillful long-range forecasts of North American heat waves from Pacific storm propagation
    (Colorado State University. Libraries, 2017) Jenney, Andrea, author; Randall, David, advisor; Barnes, Elizabeth, committee member; Anderson, Georgiana Brooke, committee member
    Extreme heat poses major threats to public health and the economy. Long- range predictions of heat waves offer little improvement over climatology despite the continuing improvements of weather forecast models. Previous studies have hinted at possible relationships between tropical West Pacific convection and subsequent anomalous near-surface air temperature and rainfall over the North American Plains. We show that the later stages of propagation of the Boreal Summer Intraseasonal Oscillation (BSISO) can be used to skillfully hindcast a number of Great Plains heat waves between 1948 and 2016 with a three-month lead time. Possible teleconnection mechanisms are investigated, with the most likely being related to a BSISO-induced reduction in Plains spring rainfall and subsequent land-atmosphere feedbacks. Our results are the first to demonstrate that a West Pacific weather event can be used to skillfully forecast US Plains heat waves with a lead time of three months.