Browsing by Author "Lee, Jeffrey A."
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Item A geographical analysis of the western Texas college service area(2017-08) Holder, Floyd William; Elbow, Gary; Lee, Jeffrey A.; Beebe, BarbaraThis thesis geographically analyzes the Western Texas College District Service Area. Chapter 1 introduces how this specific thesis began. Chapter 2 evaluates the reasons that are important to students in general when selecting a college in which to enroll and also considers factors that influence them to enroll at a specific institution. Chapter 3 evaluates the history of Western Texas College. It shows that much has been done to develop a student body after overcoming many obstacles to building up the institution. The Chapter 4 confirms the presence of a minimal population for the institution to draw upon for a student body and confirms that the institution is at a disadvantage when compared to the neighboring institutions in regard to the service area from which it draws students. The remaining chapters present how this thesis fits into the literature by offering a new approach, geographical analysis and methodology, and the findings of the analysis. The findings indicate that those from a home located near the institution will primarily enroll due to financial concerns and geographic proximity while those from farther away primarily enroll due to athletic programs offered by the institution. Those findings are robust across all age, race, sex, and grade classifications in addition to comparable parts of the prior literature. Finally, in light of the findings, recommendations for future research and suggestions for how the institution in question might address the limitations of its Designated Service Area are presented.Item A geospatial contextualization of archaic Greek epigram on Thasos(2016-05) Levine, Evan Isak; Elbow, Gary; Cao, Guofeng; Lavigne, Donald E.; Lee, Jeffrey A.; Witmore, ChristopherThis project explores the avenues by which contemporary scholars encounter Archaic Greek inscribed text. It is proposed that the standard method of recording and presenting information on this topic has played a critical part in creating voids within epigraphic scholarship, namely through a disassociation of the text from its spatial and monumental properties. Analysis of ancient accounts of epigraphic interaction highlights an experience that was much more nuanced than can be replicated through traditional philological or archaeological examination and interpretation, and one that emphasizes the spatial and contextual relationships of these inscriptions to one another. Therefore, modern epigraphic scholarship would be strengthened through the implementation of a geospatial contextualization and novel presentation. To support these claims, a case study for the geospatial contextualization of archaic Greek epigram is presented in this thesis. All extant and recorded instances of Archaic epigram on the Greek isle of Thasos are documented both spatially and visually, regardless of their present location. A methodology is proposed for the identification of potential original loci of placement for these monuments. This information is collated in a GIS and exhibited through a series of interactive maps and photogrammetric reconstructions of the original depositions of these inscriptions, all of which are displayed through a fully searchable database. This method allows for the analysis of any observable patterns in the spatial placement of grave and dedicatory inscriptions, uncovering aspects of archaic epigraphy that have been neglected in traditional scholastic examinations.Item A wind tunnel investigation to examine the role of air humidity in controlling the threshold shear velocity of a surface and in controlling the mass flux of material from a surface(2013-05) Massey, Joe; Lee, Jeffrey A.; Zobeck, Ted M.; Perry, Gad; Bateman, MarkAeolian erosion, the wind-forced movement of soil particles, is a dominant process in arid regions. The impacts of wind-driven dust emissions are numerous and can have both localized effects and far reaching impacts. The susceptibility of a soil surface to wind erosion is gauged using the threshold friction velocity (u*t), which is related to the wind speed needed for the erosion of surface material to commence. This threshold varies for every surface and depends on numerous variables, including surface soil moisture. In arid regions, which contain air-dry soils, soil moisture is the driving factor controlling changes in the threshold shear velocity of a surface at short, diurnal timescales (Ravi and D’Odorico, 2005). Therefore, an understanding of these varying moisture conditions, and the associated changes in soil erodibility, is vital in understanding and modeling aeolian soil erosion (Ravi et al., 2006). In such regions, where rainless periods are common and there is a lack of moisture provided by precipitation or capillary rise, the humidity of the overlying air is particularly influential in controlling soil moisture content at the surface (Ravi and D’Odorico, 2005). Through wind tunnel tests, this study analysed the control relative humidity had on the threshold shear velocity for three soils: a loamy fine sand, a clay loam and a sandy muck. The loamy fine sand and the clay loam material were previously studied and the results found here agreed with those from other studies (e.g., Ravi et al., 2006). The relationship found is made up of a high and low section of humidity, where the threshold shear velocity increases with humidity, and a mid-range section of humidity, where the threshold shear velocity decreases with increased humidity. The previously unstudied sandy muck also showed this relationship. The results were explained using the theory of equilibrium between the surface soil moisture and the humidity of the overlying atmosphere. In such studies, an accurate measurement of the threshold shear velocity is vital and this study compared the sensitivity of two particles sensors (Wenglor YH03PCT8 and Sensit model H10) in determining the threshold shear velocity of a soil surface. It was found that the newer Wenglor sensor recorded the threshold at considerably lower wind speeds throughout the test and for each soil. This, however, did not significantly change the relationship seen between the threshold shear velocity and relative humidity. For the first time, this study aimed to investigate the effect humidity has on the erodibility of a surface over a sustained period of time. This was done by analysing the mass flux of PM10 from each soil at a range of humidities. It was found that the initial threshold shear velocity of the surface had no control over the average mass flux of material from the surface. For the clay loam and sandy muck, the humidity also had no control over the average mass flux of material from the surface. The loamy fine sand, however, exhibited a strong, linear relationship between the humidity and the total mass removed. This was explained using a theory suggesting that the higher percentage of larger grains in this soil preferentially absorbed water from the atmosphere when compared to smaller grains, meaning smaller grains are less affected by the threshold. Finally, this study analysed the control of humidity on the time it takes for mass flux to reach its peak value. It was found that the threshold shear velocity had a substantial control over the time to mass flux. This showed that the overlying humidity of the air only affected the grains at the surface (≈top 2mm) and, under prolonged wind erosion, the initial threshold of the surface was no longer apparent at the surface and a new threshold was developed.Item An Intercomparison of the Aerosol Sensors Used in the Aerosol Research Observation Station (AEROS)(2023-08) Voelker, Stephanie; Ardon-Dryer, Karin; Lee, Jeffrey A.; Henderson, JenParticulate matter (PM) is a mixture of microscopic solid and liquid particles suspended in the atmosphere. Despite the health and safety concerns associated with PM, insufficient air quality monitoring stations exist in many areas worldwide. One region in the United States that experiences elevated PM levels, but maintains insufficient monitoring is the Southern High Plains (SHP) region of West Texas. For decades, the occurrence of high PM concentrations in the SHP has been observed due to its semi-arid environment. The exposure to elevated PM concentrations emphasizes the need for localized air quality understanding, but there is a lack of continuously operating PM monitors and data on PM measurements within the region. In 2019, there were only three air quality monitor stations in the SHP. The three stations, which are still in operation, are part of the Texas Commission of Environmental Quality (TCEQ) monitor network. The three TCEQ stations are sparsely located in Amarillo, Lubbock, and Odessa and operate off a beta attenuation method that only provides information on hourly PM2.5 concentration. The Aerosol Research Observation Station (AEROS) is an aerosol monitoring station that was implemented in March 2019 to fill PM data gaps in the SHP. Located at Texas Tech University in Lubbock, TX, AEROS provides continuous aerosol measurements of particle size distribution, total particle concentration, and concentrations of different PM sizes (PM1, PM2.5, PM4, and PM10). The AEROS aerosol measurement unit houses three aerosol sensors including the Optical Particle Sizer (OPS) 3300, the DustTrak DRX 8533EP, and the Grimm 11-D Portable Aerosol Spectrometer. These sensors are mid-cost, optically based sensors that operate using the principle of single particle scattering. In this study, intercomparisons of total particle and mass concentrations collected by the three sensors were performed for one year from March 2019 to March 2020. Similarities and differences of each sensor and their PM measurements were identified using R-squared (R2), root-mean-square error (RMSE), and mean absolute error (MAE) values as well as best-fit information. Additionally, temporal patterns of the Grimm 11-D were analyzed. Intercomparisons in this study will allow for a deeper understanding of local aerosol concentrations and aid in future air quality studies.Item An investigation of social vulnerability and storm resource availability for tornado hazards in Lubbock, Texas(2016-10-24) Morris, Ashley Elizabeth; Cao, Guofeng; Liang, Daan; Lee, Jeffrey A.The United States has the most tornado activity on the globe. These storms cause many losses of lives and property each year. Despite importance, there has been little research completed on the preparedness of a city prior to a tornado event. There are also gaps in research regarding storm resource access (storm shelter, warning technology, and educational outreach access) and social vulnerability. The goal of this study was to determine if sufficient storm resources are in place for a future tornado event in Lubbock, Texas and to offer suggestions and recommendations for improving preparedness if found. The methods involved the creation of a social vulnerability scale, citizen surveys, and regression analysis in order to assess numerous interactions between social vulnerability and resource access. As a result, it was shown that the variable of income plays a large role in readiness and resource access. It was also shown that the high vulnerability regions are located in north and east Lubbock and also feature the worst scores of preparedness and readiness. It was recommended that emergency management officials attempt to administer more shelter, technology, and educational outreach access in these communities to improve the city’s ability to withstand and recovery from a tornado event looming in the future.Item Analysis of dune morphology within the Rub’ al Khali using geospatial technology(2017-12) Almutlaq, Fahad; Mulligan, Kevin; Lee, Jeffrey A.; Cao, GuofengThe Rub’ al Khali desert (or Empty Quarter) is the largest and perhaps most significant sand sea in the world. Located on the southern Arabian Peninsula, the dune field has remained largely unexplored owing to the harsh clime and difficult terrain. While several studies have mapped the different dunes forms within the Rub’ al Khali, most of this research is based on field expeditions, the visual interpretation of air photos or the visual interpretation of satellite imagery. To build upon this previous work, this study takes advantage of geospatial technology to extract information from the data contained in global DEMs, satellite imagery and weather forecast models. The main objective here is to: 1) identify and map the different dune forms within the sand sea, 2) estimate the volume of sand and explore probable sources of sand, and 3) relate the different dune forms to the prevailing wind regime. The results from this study are very enlightening. In the first part of the study, new maps are generated showing shaded relief, the spatial variability in dune height, the spatial variability in dune texture, and profile graphs are created to examine the dune surface in cross-section. In the second part of this study, satellite imagery is analyzed to highlight differences in the color of the sand, and digital elevation models are analyzed to map the paleodrainage system, the desert floor beneath the dunes, and calculate the volume of sand. Lastly, in the third part of this study, the output from weather forecast models is used map the spatial and temporal variability in wind speed, the pathways of sand movement through the dune field and the directional variability in sand transport.Item Analysis of Dust Emission Point Sources in the Middle East(2023-05) Al Zubi, Ruba; Lee, Jeffrey A.; Ardon-Dryer, Karin; Gill, Thomas E.; Bhattachan, AbinashDust storms, also known as sandstorms or haboobs, are common natural phenomena in arid and semi-arid regions like the Middle East and pose significant challenges to the region. Moreover, the past decade has witnessed severe dust storms in Iraq, Jordan, and Syria. One of the main reasons for the increased magnitude of dust storms can be drought. This dissertation is composed of two chapters attempting to identify and analyze dust point sources in Syria, Iraq, and Jordan from the year 2010 to 2021. The first chapter is titled “Land Cover Effect on Dust Storms in the Middle East by Detecting Dust Point Sources between 2010 and 2021”. In this chapter, MODIS true color satellite images of dust storms in Iraq, Jordan, and Syria for the period 2010 - 2021 were analyzed for dust point sources detection. A total of 4923 dust point sources were visually detected from MODIS images. Results showed that the Tigris-Euphrates Basin contains ~ 90% of the points within its boundary. A significant cluster of dust source point sources in the Tigris-Euphrates Basin is confirmed by the Nearest Neighbor Ratio (NNR) of 0.41 at р < 0.001. Land cover maps were created to investigate the dust point sources of land cover and to calculate the dust emission ratio (DER). Bare land is the main land cover in the Middle East, and its DER is 1.34. The DER values for cropland, grassland, and shrubland are 0.1, 0.41, and 0.41, respectively. It was found that wetlands (occupying 1% of the total study area) have the highest DER (1.70). Wetlands contain dry lakes, parts of marshes, and drying lakes in the Tigris-Euphrates Basin area. The results of this chapter also show that, generally, no matter what the land cover class is, the DER is higher inside the Tigris-Euphrates Basin than outside of it. The second chapter of this dissertation is titled “Using NDVI as a Tool to Observe the Number of Dust Point Sources in the Middle East/ Effect of Drought and Vegetation on Dust Emission.” In this chapter, NDVI maps were produced to estimate drought conditions. The NDVI value for each dust point source was extracted through overlay analysis. Overlay analysis of dust point sources and NDVI maps revealed that 77 % of the NDVI values for the dust point sources are less than 0.1, and 99 % are 0.2 or less. Moreover, the one-way analysis of variance (ANOVA), Tukey HSD, and statistical test were performed, and the results show a statistically significant difference in the NDVI values between the different land cover types except for urban lands; where NDVI values are not statistically different from NDVI values of shrubland and bare lands (p < 0.05). In other words, results indicate that if there were a drought or insufficient precipitation in a particular year, the correlation between the NDVI value and land cover class suggests that dust point sources may be significantly generated from land cover classes such as shrubland, grassland, and cropland. This dissertation shows that poor agricultural practices (e.g., fallow practices) combined with drought (primarily in 2009 -2012) may have contributed to dust emissions from agricultural lands in Iraq, Syria, and Jordan. Therefore, it is essential to have a professional land management strategy; for instance, establishing windbreaks and vegetation barriers is recommended in the region. Additionally, regional cooperation is crucial in addressing dust issues, since dust emission, particularly from the Tigris-Euphrates Basin, can pass the borders to neighboring countries.Item Analysis of marine stratus surges in the Pacific Northwest(2014-05) Lambert, Tiffany; Lee, Jeffrey A.; Cao, Guofeng; Delahunty, TinaThis study examines the long-term trends of marine stratus surges in the Pacific Northwest and corresponding temperature changes across a local study area. Temperature change data for the Seattle Tacoma International Airport was used to assemble a dataset of marine stratus surge events from 1948-2012. The surge count data was then compared to the Pacific Decadal Oscillation Index and the Northern Oscillation Index using a Zero-Inflated Poisson regression model to analyze any relationships between the decadal climate patterns and the occurrence of surges. While there is no correlation between either the PDO or NOI and surge counts, there is a statistically significant correlation between zero counts in the surge data and the NOI monthly index value. A subset of -10°C temperature drops at SeaTac for 2003-2012 was used to compare temperature change on these surge dates with temperature change at various weather stations across a local study area. Descriptive statistics on the area temperature changes were calculated, and a bubble chart and kriging maps were generated to show how this temperature change is experienced across the study area. Analysis of this data shows that a temperature change associated with SeaTac surge events is varied across the study area, and previously stated definition of a marine stratus surge is not appropriate for use at stations other than SeaTac.Item Analysis of percipitation and saturated thickness of the Texas Ogallala Aquifer(2010-08) Warren, Ada R.; Mulligan, Kevin; Lee, Jeffrey A.; Johnson, JeffThe Ogallala Aquifer is an important source of groundwater for agricultural and municipal supplies on the Texas High Plains. It is widely recognized that water levels in the aquifer are declining at an average rate of about one foot per year. Declining aquifer water levels are a result of water extraction occurring faster than aquifer recharge. Although the water levels of the aquifer are declining, the rate of decline fluctuates year-to-year and it seems reasonable to assume that variations in annual or seasonal precipitation contribute to the variability in the rate of decline. The precipitation rates affect the amount of water extracted by producers for irrigating crops. To address this problem, the objective of this thesis was to determine if precipitation has an effect on the rate of water extraction from the Ogallala Aquifer. This study compares the annual change in saturated thickness with precipitation data for the study area to determine the relationship between aquifer drawdown and precipitation. Well data for the Ogallala Aquifer were acquired for 1990 to 2008 for 10 counties on the Southern High Plains. The well data were used to calculate saturated thickness and rate of decline for each year. The saturated thickness was compared with annual and seasonal precipitation totals for each year. The results from this study found that annual precipitation amount has a statistically significant effect on the rate of decline of saturated thickness of the Ogallala Aquifer in Texas. Furthermore, seasonal precipitation will have a greater effect on the rate of decline of saturated thickness than annual precipitation.Item Analysis of the wind regime and dune morphology within the Namib Sand Sea(2022-05) Hamelwright, Bryce; Lee, Jeffrey A.; Mulligan, Kevin R.This study examines the relationship between the wind regime of the Namib Desert and the morphology of the sand dunes found within the Namib. Typically, research in dune morphology involves gathering wind data from wind stations found in the study area. However, in the Namib Desert there are only a few weather stations. To address this problem, this study follows the previous work of Almutlaq (217) using the Global Ensemble Forecast System (GEFS) to create virtual wind stations. With these virtual wind stations, Fryberger’s (1979) methods of calculating the drift potential (DP), resultant drift potential (RDP), and the RDP/DP ratio are used to quantify the effective wind regime of the sand sea. The main objectives are to: 1) visually classify and map the main dunes types of found within the desert, 2) use wind data from the GEFS model to calculate and map the monthly RDP and RDP/DP ratios at a 0.5º spatial resolution, 3) aggregate and map these monthly RDP and RDP/DP ratios to characterize the annual wind regime and 4) relate these RDP and RDP/DP ratios to the varied dune morphology. The results from this study are presented in a map categorizing the different dune types found in the Namib, a map of dune height, and monthly and annual maps showing the effective wind regime as represented by the RDP and RDP/DP ratios. Overall, the types of dunes found in the Namib are consistent with the expected nature of the wind regime. The transverse dunes in the western part of the sand sea are formed by unidirectional winds, the linear dunes in the central part of the sand sea are formed in by acute bimodal winds, and the star dunes in the eastern part of the sand seas are formed by multidirectional winds.Item Complex classification of singularities of reducible septic curves(2016-05) Gonzalez, Elias; Weinberg, David A.; Lee, Jeffrey A.; Gelca, RazvanThere are 163 types of quadruple points, 139 types of quintuple points, and 25 types of sextuple points for complex reducible septic curves. 20 types of double points and 69 types of triple points are constructed for complex reducible septic curves. Thus, 417 types of singularities are exhibited.Item Cyclicity, Dune Migration, and Wind Velocity in Lower Permian Eolian Strata, Manitou Springs, CO(2017-06-07) Pike, James Daniel; Sweet, Dustin E.; Lee, Jeffrey A.; Lehman, ThomasThe Permian of western North America is characterized by a long-term drying trend, due in part to supermonsoonal conditions related to the assembly on Pangea. This trend is reflected in the gradational contact of the Pennsylvanian alluvial-fluvial Fountain Formation and the early Permian eolian Ingleside Formation. The Ingleside Formation at Manitou Springs is characterized by two major eolian depositional intervals, punctuated by fluvial-alluvial facies. The shift from eolian to alluvial-fluvial depositional systems represents a major pulse of humidity during an otherwise arid period. Eolian facies are moderately-sorted, subrounded, fine-grained, sub-arkosic sandstone. Cross stratification is up to 9 meters, and strata exhibits internal ripple laminae. Eolian cross-strata are periodically truncated by parallel to sub-parallel zones consisting of laterally continuous massive to weakly planar stratified muddy sandstones. Rhizoliths are locally present within these zones, and zones demonstrate abundant clay and carbonate cementation in thin section. Zone thicknesses range from true surfaces with no thickness up to 1.7 meters. These zones are highest-order present in the stratigraphy, and are inferred to be Super Bounding Surfaces (SBS), which likely reflect deflation of the erg field to an elevated water table due to changes in sedimentary flux, aerodynamic and/or environmental conditions. Following erosion to an elevated water table, deposition occurred in a stabilized and/or wet sand flat system. Fourteen SBS zones were identified in the eolian strata at Red Rock Canyon Open Space. SBS zones separate distinct intervals of eolian migration and deposition. Mean paleowind directions for the measured intervals range from 230 to 254 degrees, indicating northeasterly to easterly winds. Wind directions are consistent with an equatorial circulation pattern, and are likely influenced by the lack of highlands to the west (Woodland Park Trough). Paleowind threshold velocities range from 24.1 Km/hr to 32.4 Km/hr using D10 grain sizes and a height of 1.5 meters above bedding surfaces. As SBS are low porosity, low permeability zones, they likely act as fluid baffles and partition reservoir intervals from one another. Additionally, these zones can act as pathways along which fluids can flow.Item Detection of black-tailed prairie dogs through the use of high resolution aerial imagery and LiDAR data(2018-12) Jost, Ryan; Lee, Jeffrey A.; Portillo, Carlos; Zhu, ZheIn this study, remote sensing and landcover classification were utilized to detect black-tailed prairie dog towns throughout the city of Lubbock without the use of field visits. Using eight high resolution (0.5 meters) aerial images covering roughly 374 square kilometers, training data identifying the location of prairie dog towns, alongside training sites for other basic landcover types, were used to highlight the areas containing black-tailed prairie dogs. Intensity values found within freely acquired LiDAR data were also used in conjunction with the aerial imagery, to potentially improve accuracy. In addition to random-point accuracy analyses, a region-based accuracy assessment—in which large cell clusters were highlighted within classified imagery—was completed. This enabled me to easily mark detected areas, as well as assess the quality of training data. Overall accuracy with just the aerial imagery was 37%, which was later improved to 46% with the inclusion of the LiDAR intensity data. Accuracy was further improved to the range of 62-68% after examining the regions created through classification. Although accuracy throughout the study was not necessarily high, the methods used can potentially reduce field work in conservation or habitat research for large areas and highlighted many previously unknown prairie dog towns.Item Effect of soil texture and calcium carbonate on laboratory-generated dust emissions from SW North America(2013-05) Mockford, Tom; Lee, Jeffrey A.; Perry, Gad; Zobeck, Ted M.; Bateman, MarkUnderstanding the controls of mineral dust emissions and their particle size distributions during wind-erosion events is critical as dust particles play a significant impact in shaping the earth’s climate. It has been suggested that emission rates and particle size distributions are independent of soil chemistry and soil texture. In this study, 37 samples of wind-erodible surface soils from the High Plains regions of Texas, New Mexico and Colorado were analyzed by the Lubbock Dust Generation, Analysis and Sampling System (LDGASS) and a Beckman-Coulter particle multisizer. The LDGASS created dust emissions in a controlled laboratory setting using a rotating arm, which allows particle collisions. The emitted dust was transferred to a chamber where particulate matter concentration was recorded using a DataRam and MiniVol filter and dust particle size distribution was recorded using a GRIMM particle analyzer. Particle size analysis was also determined from samples deposited on the Mini-Vol filters using a Beckman-Coulter particle multisizer. Soil textures of source samples ranged from sands and sandy loams to clays and silts. Results suggest that total dust emissions increased with increasing soil clay and silt content and decreased with increasing sand content. Particle size distribution analysis showed a similar relationship; soils with high silt content produced the widest range of dust particle sizes and the smallest dust particles. Sand grains produce the largest dust particles. The chemical control on dust emissions by calcium carbonate content is also discussed.Item Exploring the character of place in Lubbock through interviews, mental maps, and the place histories of local musicians(2013-05) Grann, Caitlin; Elbow, Gary; Lee, Jeffrey A.; Tomlinson, Susan L.This research utilizes interviews with local musicians, mental maps collected from them, and the words of their music to construct the spatial character of Lubbock, Texas as expressed by its musicians. It answers three questions: Do the methods used answer the following two questions? How do musicians interact with this distinctive cultural and physical environment? To what extent is this an example of Edward Soja’s concept of Thirdspace? The trialectic framework provided by Soja’s theory of Thirdspace recognizes the spatiality of relationships not just between individuals and their landscapes, but individuals within their community. Further, it demonstrates the influence these relationships have on socially constructed space.Item Hearing the deaf community: Miscommunication of medical accommodations(2019-12) Glaeser, Emily; Carter, Perry L.; Wagner, Brandon; Lee, Jeffrey A.Most people in the Deaf community do not see themselves as damaged or helpless, but accommodations allow them to live and experience life on their own terms. Making accommodations accessible gives them the choice of how to live their life. The purpose of this paper is to identify areas of miscommunication and accommodation service accessibility in Austin and Lubbock, Texas for individuals who are Deaf/deaf or hard-of-hearing. The Deaf and hard-of-hearing community will fill out a survey about accommodations and communication preferences throughout Austin and Lubbock. This data will be analyzed to show which services are being met by the community and which ones can be improved. Expecting to see that patients are not being properly accommodated which causes communication issues, as well as finding what accommodations are preferred and effective.Item High-resolution mapping of ground-level fine particulate matter and the associated human health risks(2018-08) Liu, Ying; Cao, Guofeng; Vanos, Jennifer; Lee, Jeffrey A.; Mulligan, KevinFine particulate matter with aerosol dynamic diameters equal to or less than 2.5 micrometers (PM2.5) is a major component of air pollutants widely threatening public health. To control and mitigate its adverse effects on human health, it is essentially important to explore the potential factors influencing ground-level PM2.5 concentrations and the associations between long-term PM2.5 exposure and its health outcomes. In my dissertation, I incorporate the spatial synoptic classification weather type data to investigate the impacts of meteorological factors on ground-level PM2.5 concentrations in a holistic fashion rather than individual meteorological variables separately. It was found that tropical (polar) weather types have positive (negative) effects on the ground-level PM2.5 concentrations and these positive (negative) effects varied seasonally and geographically. Accurate mapping of ground-level PM2.5 concentrations is the prerequisite for investigating the adverse effect of PM2.5 exposure on human health. However, the current PM2.5 monitoring networks leave many people unmonitored. Satellite-derived gridded PM2.5 images from chemical transport models (CTM) have demonstrated unique attractiveness in terms of their geographic and temporal coverage but often yield results with a coarse spatial resolution and tend to ignore or simplify the impact of geographic and socioeconomic factors on PM2.5 concentrations. In the second part of my dissertation, a random forests-based regression kriging (RFRK) approach was developed to improve the spatial resolution of a CTM-derived PM2.5 dataset from 0.1° to 0.01° with a combined use of in situ PM2.5 observations, brightness of nighttime lights, vegetation index, and elevation. The accuracy and advantages of the proposed approach are demonstrated by comparing the results with an existing PM2.5 dataset with the same spatial resolution. The effectiveness of the geographical variables in long-term PM2.5 mapping were highlighted and the contribution of each variable to the spatial distribution of PM2.5 concentrations was discussed. The third part of my dissertation targets on mapping the distribution of PM2.5-attributable mortality for detecting the potential benefits of PM2.5 control. To highlight the impact of geographic scales and variations of geospatial datasets on the estimation of PM2.5-attributable mortalities, I compared the estimations derived from PM2.5 concentration datasets at different spatial resolutions (i.e., 0.01° and 0.1°) and mortality statistics at different geographic scales (i.e., sub-regional and county-level). Using ischemic heart diseases (IHD) in the contiguous United States (U.S.) as a case study, it was found that the estimated PM2.5-IHD mortalities from the 0.1° PM2.5 dataset tend to be smaller than the estimations from the 0.01° PM2.5 datasets, while the estimated PM2.5-IHD mortalities from the sub-regional-level mortality rates tend to be larger than the estimations from the county-level ones. Simultaneously, the spatiotemporal change of PM2.5-attributable IHD mortality were extracted during 2000 and 2015 and it showed the PM2.5-IHD deaths decreased approximate 50%. A scenario analysis indicated up to 90% deaths could be avoided with the PM2.5 concentration decreased by 4 μg/m3 throughout the country. Influences of long-term PM2.5 exposure on public health have been investigated by many previous studies. However, reliability of those studies may be affected by limited measurements or inaccurate PM2.5 estimations. The last part of my dissertation linked the RFRK-refined PM2.5 dataset with fine spatial resolution and high accuracy to the hospital admission databases for Arizona. Relative risks (RRs) of PM2.5-attributable morbidity were calculated for all-cause, skin cancer, asthma, cerebrovascular, chronic respiratory, and heart diseases. Logarithmic risk functions for all-cause, skin cancer, asthma, and heart diseases and polynomial risk functions for respiratory and cerebrovascular diseases are developed for the total population. I also examined whether long-term PM2.5 exposure had varied intensities on human health among different subpopulations. Female had significantly higher risk of PM2.5-attributable morbidity than those of male for all-cause and heart diseases. African Americans are more vulnerable than Whites and Hispanics for all-cause, heart, and respiratory diseases. Hispanics more easily suffer from skin cancer than Whites from PM2.5 exposure, while Whites’ RRs for cerebrovascular diseases are apparently higher than those of Hispanics.Item Human Interactions with the Aquatic Ecosystems of The Los Angeles River: The Creation of the LA River as a Human Landscape and the Effect of Exotic Fish on Human Activity(2017-11-29) Post, Jason M.; Carter, Perry L.; Cao, Guofeng; Lee, Jeffrey A.; Mulligan, KevinThe Los Angeles River is a complex dynamic human landscape. Humans have interacted with, and modified the LA River for their convenience since prehistory (Gumprecht 2001). Situated within the human-environment interactions literature, this project works from a critical paradigm stance to explore the Los Angeles River as a human landscape. Prior works focus merely on quantifying fish community assemblages on the LA River, and neglect to view these fish as artifacts of a diverse city. The LA River is a novel ecology, an example of a natural place that exists in a state altered by human activity. Recent movements in the literature argue for the acceptance of novel ecologies as "nature". First, this project evaluates current exotic fish assemblages on the LA River. Fish surveys establish a recent update to prior studies evaluating exotic fish on the Los Angeles River. Through the innovative application of side imaging (SI) sonar, aquatic habitats are mapped. An overlay analysis compared patterns of habitat use on the LA River to the natural history literature describing these fish species' patters of habitat use expressed in native ranges. Lastly, this project combines physical habitat data, with ecological data to establish in analysis of similarity, comparing the traits of an exotic species’ home range distribution to those of the Los Angeles River. This provides a preliminary assessment of the human dimensions of the River as well as ecological adaptations of fishes that allow them to thrive. This study found that native ranges were statistically similar to the LA River. Moreover, exotic fish from ecoregions with a greater human footprint were found to do better as exotics in another human landscape (LA River) than those from areas with less human disturbance. Next, a qualitative study of LA River angler internet videos showed that anglers' behavior and tactics vary along demographic lines. The complex social and cultural issues of the surrounding city translate to the LA River as evidenced by fishing activities. Sustenance fishing was discovered, as was underlying issues of race and class, all evident in angler behavior. Since nature is a social construction (Cronon 1996), a product of one's cultural upbringing and social discourse, understanding who interacts with the river, and how interactions vary along demographic lines, provide a basis to critique current restoration and revitalization efforts. The river should arguably reflect the reality of those who use and interact with it, not those with the most power or money. Many people currently still view the Los Angeles River is as “natural” despite the presence of exotic and introduced fish species, and a concrete edifice. A long standing stigma has plagued the LA River, causing people to view it as a dirty, dystopian landscape. This study, however, shows that in many ways, it is still a “natural” and thriving ecosystem. Human activity has created the modern incarnation of the Los Angeles River, and human activity is responsible for creating the River as it exists today. The "human" and "natural" components of the LA River have become inseparable. Due to the significant role human activity plays in shaping the Los Angeles River and its species, this project upholds the notion that the aquatic habitats of the Los Angeles River are indeed a human landscape.Item Identifying and spatio-temporal analysis of dust point sources in southwestern United States and applying robotics in wind erosion studies(2020-12) Kandakji, Tarek; Lee, Jeffrey A.; Mulligan, Kevin R.; Song, Xiaopeng; Ardon-Dryer, Karin; Gill, Thomas E.; Van Pelt, Robert S.; Zhu, ZheThis dissertation is composed of three studies; two of them were published as scientific articles in two peer-reviewed academic journals. The first study is entitled “Identifying and Characterizing Dust Point Sources in the Southwestern United States using Remote Sensing and GIS” and it is published in Geomorphology. Appendix A is a screenshot of the first page of the published article showing Volume number and the related Digital Object Identifier (DOI). This study aimed to detect dust point sources in the Southern Great Plains and the Chihuahuan Desert of the United States (U.S.) between the years 2001 and 2016 using satellite images. The detected dust points were later characterized based on the geomorphology and the land use/land cover type of their emission source. A total of 1508 dust point sources were detected. The results showed that ephemeral lakes (i.e. playas) geomorphic class produce the most dust sources in proportion to their area. Cultivated croplands enclose 43% of the dust points, while shrublands and grasslands, combined, enclose 45% of the points. Results from this study confirm the importance of playas as a dynamic source of dust in southwestern U.S. Moreover, this study suggests that anthropogenic factors may be playing a major role in dust emission within southwestern U.S. The results of this study highlights the need to perform further spatio-temporal and quantitative analysis on the detected dust point sources to quantify the contribution of different land cover types on dust emission in the region. This suggestion was fulfilled in the second study of this dissertation. The second study is entitled “Drought and Land Use/Land Cover Impact on Dust Sources in Southern Great Plains and Chihuahuan Desert of the US: Inferring Anthropogenic Effect” and it is published in the Science of The Total Environment. Appendix B is a screenshot of the first page of the published manuscript showing the Volume number and the related DOI. The objective of this research was using the dust point sources dataset produced in the first study to test the hypothesis that there is a statistically significant association between drought level and land cover that may contribute to dust emission in the Southern Great Plains and Chihuahuan Desert regions of the U.S. To reach this objective, several analysis were conducted including spatio-temporal analysis and statistical analysis. The chi-square analysis results showed a significant association between land use type and drought level on dust emission (χ2 (6) = 45.54, р < 0.001), thus confirming the proposed hypothesis. Results from this study indicate that human activities in dust-prone regions will worsen the negative impacts of drought by changing land cover and making the soil more erodible in multiple ways. The third study of this dissertation is entitled “In Situ Measurement of Wind Shear Stress using the Rhex Hexapod Robot Platform”. In this work we used the rigid hexapod robot (RHex) to carry 3D sonic anemometers at two near surface heights to collect wind data. The rationale behind using a mobile senor in the field is to model wind and dust emission using a robust technique rather than using the traditional wind tunnels. The real conditions in the field are hard to simulate in a wind tunnel since it utilizes artificial wind stream flow that is restrained by the walls of the wind tunnel. Moreover, wind tunnel experiments fail to replicate air temperature and moisture content that affect momentum flux. Momentum flux within the boundary layer is an important factor in generating shear stress on the surface. Solar radiation in the open field can cause heating of the air at the surface, which will affect convective overturn and increase wind velocity. The robot scanned a 10 m × 10 m study area in an open field and collected wind and shear stress data as affected by four types of artificial roughness elements simulating a solid object like tree trunk and natural shrubs with different porosity and density. The shear stress and the wind speed data collected by the robot appear to be randomly distributed and does not follow any pattern, which reflects the complexity of real world conditions. These conditions are controlled by many factors, like wind gusts, surface heating, and resulting turbulence from convective overturn. However, the shading effect of solid object was observed, and its effect extends up to 0.5 m downwind of the object at 0.2 m height above the ground (midpoint between ground surface and anemometer mounted at 0.4 m). This study provides an important guideline for future studies, and highlights the potential of using RHex in further studies. Researchers in successive studies should try to fix the limitations of using RHex and improve the study design based on this work.Item John Muir and Jeanne Carr: Environmentalism in the Victorian era(1993-12) Stuckey, Harold T.; Lee, Jeffrey A.; Kelley, Karol; Urban, Lloyd V.