scholarly journals Detection and variability of combustion-derived vapor in an urban basin

2018 ◽  
Author(s):  
Richard P. Fiorella ◽  
Ryan Bares ◽  
John C. Lin ◽  
James R. Ehleringer ◽  
Gabriel J. Bowen
Keyword(s):  
Water Vapor ◽  
Urban Areas ◽  
Salt Lake ◽  
Atmospheric Stability ◽  
Salt Lake City ◽  
Combustion Products ◽  
Vapor Source ◽  
Excess Value ◽  
Lake City ◽  
Co2 Excess

Abstract. Water emitted during combustion may comprise a significant portion of ambient humidity (> 10 %) in urban areas, where combustion emissions are strongly focused in space and time. Stable water vapor isotopes can be used to apportion measured humidity values between atmospherically transported and combustion-derived water vapor, as combustion vapor possesses an unusually negative deuterium excess value (d-excess, d = δ2H − 8δ18O). We investigated the relationship between d-excess of atmospheric vapor, ambient CO2 concentrations, and atmospheric stability across four winters in Salt Lake City, UT. We found a robust inverse relationship between CO2 excess above background and d-excess on sub-diurnal to seasonal timescales, which was most prominent during periods of strong atmospheric stability that occur during Salt Lake City winter. We developed a framework for partitioning changes in water vapor d-excess between advective changes in vapor and the addition of combustion derived vapor. Using a Keeling-style mixing model approach, we estimated the d-excess of combustion derived vapor in Salt Lake City to be between −125 ‰ and −308 ‰, broadly consistent with theoretical estimates. Moreover, our analysis highlights that changes in the observed d-excess during periods of high atmospheric stability cannot be explained without a vapor source possessing a strongly negative d-excess value. Further refinements in our estimate of the isotopic composition of combustion derived vapor require constraints on valley-scale stoichiometry between CO2 and H2O in combustion products, yet our results demonstrate the utility of stable water vapor isotopes to constrain contributions of combustion to urban humidity and meteorology.

scholarly journals Detection and variability of combustion-derived vapor in an urban basin

2018 ◽  
Vol 18 (12) ◽  
pp. 8529-8547 ◽  
Author(s):  
Richard P. Fiorella ◽  
Ryan Bares ◽  
John C. Lin ◽  
James R. Ehleringer ◽  
Gabriel J. Bowen
Keyword(s):  
Water Vapor ◽  
Fossil Fuel ◽  
Salt Lake ◽  
Atmospheric Stability ◽  
Salt Lake City ◽  
Fuel Combustion ◽  
Fossil Fuel Combustion ◽  
Vapor Source ◽  
Excess Value ◽  
Lake City

Abstract. Water emitted during combustion may comprise a significant portion of ambient humidity (>  10 %) in urban areas, where combustion emissions are strongly focused in space and time. Stable water vapor isotopes can be used to apportion measured humidity values between atmospherically transported and combustion-derived water vapor, as combustion-derived vapor possesses an unusually negative deuterium excess value (d-excess, d  =  δ2H − 8δ18O). We investigated the relationship between the d-excess of atmospheric vapor, ambient CO2 concentrations, and atmospheric stability across four winters in Salt Lake City, Utah. We found a robust inverse relationship between CO2 excess above background and d-excess on sub-diurnal to seasonal timescales, which was most prominent during periods of strong atmospheric stability that occur during Salt Lake City winter. Using a Keeling-style mixing model approach, and assuming a molar ratio of H2O to CO2 in emissions of 1.5, we estimated the d-excess of combustion-derived vapor in Salt Lake City to be −179 ± 17 ‰, consistent with the upper limit of theoretical estimates. Based on this estimate, we calculate that vapor from fossil fuel combustion often represents 5–10 % of total urban humidity, with a maximum estimate of 16.7 %, consistent with prior estimates for Salt Lake City. Moreover, our analysis highlights that changes in the observed d-excess during periods of high atmospheric stability cannot be explained without a vapor source possessing a strongly negative d-excess value. Further refinements in this humidity apportionment method, most notably empirical validation of the d-excess of combustion vapor or improvements in the estimation of the background d-excess value in the absence of combustion, can yield more certain estimates of the impacts of fossil fuel combustion on urban humidity and meteorology.

scholarly journals The Traverse Ridge Paleoseismic Site and Ruptures Crossing the Boundary Between the Provo and Salt Lake City Segments of the Wasatch Fault Zone, Utah, United States

2021 ◽  
Vol 9 ◽  
Author(s):  
Nathan A. Toké ◽  
Joseph Phillips ◽  
Christopher Langevin ◽  
Emily Kleber ◽  
Christopher B. DuRoss ◽  
...  
Keyword(s):  
Fault Zone ◽  
Urban Areas ◽  
Salt Lake ◽  
Salt Lake City ◽  
The Holocene ◽  
Fault Segment ◽  
Segment Boundary ◽  
Lake City ◽  
Fault Trace ◽  
Wasatch Fault

How structural segment boundaries modulate earthquake behavior is an important scientific and societal question, especially for the Wasatch fault zone (WFZ) where urban areas lie along multiple fault segments. The extent to which segment boundaries arrest ruptures, host moderate magnitude earthquakes, or transmit ruptures to adjacent fault segments is critical for understanding seismic hazard. To help address this outstanding issue, we conducted a paleoseismic investigation at the Traverse Ridge paleoseismic site (TR site) along the ∼7-km-long Fort Canyon segment boundary, which links the Provo (59 km) and Salt Lake City (40 km) segments of the WFZ. At the TR site, we logged two trenches which were cut across sub-parallel traces of the fault, separated by ∼175 m. Evidence from these exposures leads us to infer that at least 3 to 4 earthquakes have ruptured across the segment boundary in the Holocene. Radiocarbon dating of soil material developed below and above fault scarp colluvial packages and within a filled fissure constrains the age of the events. The most recent event ruptured the southern fault trace between 0.2 and 0.4 ka, the penultimate event ruptured the northern fault trace between 0.6 and 3.4 ka, and two prior events occurred between 1.4 and 6.2 ka (on the southern fault trace) and 7.2 and 8.1 ka (northern fault trace). Colluvial wedge heights of these events ranged from 0.7 to 1.2 m, indicating the segment boundary experiences surface ruptures with more than 1 m of vertical displacement. Given these estimates, we infer that these events were greater than Mw 6.7, with rupture extending across the entire segment boundary and portions of one or both adjacent fault segments. The Holocene recurrence of events at the TR site is lower than the closest paleoseismic sites at the adjacent fault segment endpoints. The contrasts in recurrence rates observed within 15 km of the Fort Canyon fault segment boundary may be explained conceptually by a leaky segment boundary model which permits spillover events, ruptures centered on the segment boundary, and segmented ruptures. The TR site demonstrates the utility of paleoseismology within segment boundaries which, through corroboration of displacement data, can demonstrate rupture connectivity between fault segments and test the validity of rupture models.

scholarly journals Use of Salt Lake City URBAN 2000 Field Data to Evaluate the Urban Hazard Prediction Assessment Capability (HPAC) Dispersion Model

2005 ◽  
Vol 44 (4) ◽  
pp. 485-501 ◽  
Author(s):  
Joseph C. Chang ◽  
Steven R. Hanna ◽  
Zafer Boybeyi ◽  
Pasquale Franzese
Keyword(s):  
Urban Areas ◽  
Salt Lake ◽  
Dispersion Model ◽  
Salt Lake City ◽  
Model Configuration ◽  
Meteorological Input ◽  
The Mean ◽  
Lake City ◽  
Urban Hazard ◽  
Random Scatter

Abstract After the terrorist incidents on 11 September 2001, there is a greatly heightened concern about the potential impacts of acts of terrorism involving the atmospheric release of chemical, biological, radiological, and nuclear (CBRN) materials in urban areas. In response to the need for an urban CBRN model, the Urban Hazard Prediction Assessment Capability (Urban HPAC) transport and dispersion model has been developed. Because HPAC is widely used by the Department of Defense community for planning, training, and operational and tactical purposes, it is of great importance that the new model be adequately evaluated with urban datasets to demonstrate its accuracy. This paper describes evaluations of Urban HPAC using the “URBAN 2000” urban tracer and meteorological field experiment data from Salt Lake City, Utah. Four Urban HPAC model configuration options and five plausible meteorological input data options—ranging from data-sparse to data-rich scenarios—were considered in the study, thus leading to a total of 20 possible model combinations. For the maximum concentrations along each sampling arc for each intensive operating period (IOP), the 20 Urban HPAC model combinations gave consistent mean overpredictions of about 50%, with a range over the 20 model combinations from no overprediction to a factor-of-4 overprediction in the mean. The median of the random scatter for the 20 model combinations was about a factor of 3 of the mean, with a range over the 20 model combinations between a factor of about 2 and 9. These performance measures satisfy previously established acceptance criteria for dispersion models.

Effects of Snow Cover and Atmospheric Stability on Winter PM2.5 Concentrations in Western U.S. Valleys

2015 ◽  
Vol 54 (6) ◽  
pp. 1191-1201 ◽  
Author(s):  
Mark C. Green ◽  
Judith C. Chow ◽  
John G. Watson ◽  
Kevin Dick ◽  
Daniel Inouye
Keyword(s):  
Snow Cover ◽  
Urban Areas ◽  
Salt Lake ◽  
Atmospheric Stability ◽  
Salt Lake City ◽  
Carbonaceous Aerosol ◽  
Radiosonde Data ◽  
Chemical Components ◽  
Emission Controls ◽  
Heat Deficit

AbstractMany populated valleys in the western United States experience increased concentrations of particulate matter with diameter of less than 2.5 μm (PM2.5) during winter stagnation conditions. Further study into the chemical components composing wintertime PM2.5 and how the composition and level of wintertime PM2.5 are related to meteorological conditions can lead to a better understanding of the causes of high PM2.5 and aid in development and application of emission controls. The results can also aid in short-term air-pollution forecasting and implementation of periodic emission controls such as burning bans. This study examines relationships between PM2.5 concentrations and wintertime atmospheric stability (defined by heat deficit) during snow-covered and snow-free conditions from 2000 to 2013 for five western U.S. urbanizations: Salt Lake City, Utah; Reno, Nevada; Boise, Idaho; Missoula, Montana; and Spokane, Washington. Radiosonde data were used where available to calculate daily heat deficit, which was compared with PM2.5 concentration for days with snow cover and days with no snow cover. Chemically speciated PM2.5 data were compared for snow-cover and snow-free days to see whether the chemical abundances varied by day category. Wintertime PM2.5 levels were highly correlated with heat deficit for all cities except Spokane, where the airport sounding does not represent the urban valley. For a given static stability, snow-cover days experienced higher PM2.5 levels than did snow-free days, mainly because of enhanced ammonium nitrate concentrations. Normalizing average PM2.5 to the heat deficit reduced year-to-year PM2.5 variability, resulting in stronger downward trends, mostly because of reduced carbonaceous aerosol concentrations. The study was limited to western U.S. cities, but similar results are expected for other urban areas in mountainous terrain with cold, snowy winters.

scholarly journals CO2 and Carbon Emissions from Cities: Linkages to Air Quality, Socioeconomic Activity, and Stakeholders in the Salt Lake City Urban Area

2018 ◽  
Vol 99 (11) ◽  
pp. 2325-2339 ◽  
Author(s):  
John C. Lin ◽  
Logan Mitchell ◽  
Erik Crosman ◽  
Daniel L. Mendoza ◽  
Martin Buchert ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Air Quality ◽  
Carbon Emissions ◽  
Urban Areas ◽  
Salt Lake ◽  
Salt Lake City ◽  
The United States ◽  
Metropolitan Region ◽  
The World ◽  
Lake City

AbstractUrban areas are responsible for a substantial proportion of anthropogenic carbon emissions around the world. As global populations increasingly reside in cities, the role of urban emissions in determining the future trajectory of carbon emissions is magnified. Consequently, a number of research efforts have been started in the United States and beyond, focusing on observing atmospheric carbon dioxide (CO2) and relating its variations to carbon emissions in cities. Because carbon emissions are intimately tied to socioeconomic activity through the combustion of fossil fuels, and many cities are actively adopting emission reduction plans, such urban carbon research efforts give rise to opportunities for stakeholder engagement and guidance on other environmental issues, such as air quality.This paper describes a research effort centered in the Salt Lake City, Utah, metropolitan region, which is the locus for one of the longest-running urban CO2 networks in the world. The Salt Lake City area provides a rich environment for studying anthropogenic emissions and for understanding the relationship between emissions and socioeconomic activity when the CO2 observations are enhanced with a) air quality observations, b) novel mobile observations from platforms on light-rail public transit trains and a news helicopter, c) dense meteorological observations, and d) modeling efforts that include atmospheric simulations and high-resolution emission inventories.Carbon dioxide and other atmospheric observations are presented, along with associated modeling work. Examples in which the work benefited from and contributed to the interests of multiple stakeholders (e.g., policymakers, air quality managers, municipal government, urban planners, industry, and the general public) are discussed.

scholarly journals Vapor hydrogen and oxygen isotopes reflect water of combustion in the urban atmosphere

2015 ◽  
Vol 112 (11) ◽  
pp. 3247-3252 ◽  
Author(s):  
Galen Gorski ◽  
Courtenay Strong ◽  
Stephen P. Good ◽  
Ryan Bares ◽  
James R. Ehleringer ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Water Vapor ◽  
Water Cycle ◽  
Salt Lake ◽  
Urban Climate ◽  
Salt Lake City ◽  
Atmospheric Model ◽  
Isotopic Signature ◽  
Urban Atmosphere ◽  
Lake City

Anthropogenic modification of the water cycle involves a diversity of processes, many of which have been studied intensively using models and observations. Effective tools for measuring the contribution and fate of combustion-derived water vapor in the atmosphere are lacking, however, and this flux has received relatively little attention. We provide theoretical estimates and a first set of measurements demonstrating that water of combustion is characterized by a distinctive combination of H and O isotope ratios. We show that during periods of relatively low humidity and/or atmospheric stagnation, this isotopic signature can be used to quantify the concentration of water of combustion in the atmospheric boundary layer over Salt Lake City. Combustion-derived vapor concentrations vary between periods of atmospheric stratification and mixing, both on multiday and diurnal timescales, and respond over periods of hours to variations in surface emissions. Our estimates suggest that up to 13% of the boundary layer vapor during the period of study was derived from combustion sources, and both the temporal pattern and magnitude of this contribution were closely reproduced by an independent atmospheric model forced with a fossil fuel emissions data product. Our findings suggest potential for water vapor isotope ratio measurements to be used in conjunction with other tracers to refine the apportionment of urban emissions, and imply that water vapor emissions associated with combustion may be a significant component of the water budget of the urban boundary layer, with potential implications for urban climate, ecohydrology, and photochemistry.

scholarly journals WRF Simulations of the Urban Circulation in the Salt Lake City Area for CO2 Modeling

2013 ◽  
Vol 52 (2) ◽  
pp. 323-340 ◽  
Author(s):  
Thomas Nehrkorn ◽  
John Henderson ◽  
Mark Leidner ◽  
Marikate Mountain ◽  
Janusz Eluszkiewicz ◽  
...  
Keyword(s):  
Urban Areas ◽  
Atmospheric Transport ◽  
Salt Lake ◽  
Dispersion Model ◽  
Salt Lake City ◽  
National Research Council ◽  
Urban Canopy ◽  
Particle Dispersion ◽  
Near Surface ◽  
Lake City

AbstractA recent National Research Council report highlighted the potential utility of atmospheric observations and models for detecting trends in concentrated emissions from localized regions, such as urban areas. The Salt Lake City (SLC), Utah, area was chosen for a pilot study to determine the feasibility of using ground-based sensors to identify trends in anthropogenic urban emissions over a range of time scales (from days to years). The Weather Research and Forecasting model (WRF) was combined with a Lagrangian particle dispersion model and an emission inventory to model carbon dioxide (CO2) concentrations that can be compared with in situ measurements. An accurate representation of atmospheric transport requires a faithful modeling of the meteorological conditions. This study examines in detail the ability of different configurations of WRF to reproduce the observed local and mesoscale circulations, and the diurnal evolution of the planetary boundary layer (PBL) in the SLC area. Observations from the Vertical Transport and Mixing field experiment in 2000 were used to examine the sensitivity of WRF results to changes in the PBL parameterization and to the inclusion of an urban canopy model (UCM). Results show that for urban locations there is a clear benefit from parameterizing the urban canopy for simulation of the PBL and near-surface conditions, particularly for temperature evolution at night. Simulation of near-surface CO2 concentrations for a 2-week period in October 2006 showed that running WRF at high resolution (1.33 km) and with a UCM also improves the simulation of observed increases in CO2 during the early evening.

scholarly journals Investigation of Indoor and Outdoor Fine Particulate Matter Concentrations in Schools in Salt Lake City, Utah

2022 ◽  
Author(s):  
Daniel L Mendoza ◽  
Tabitha M Benney ◽  
Ryan Bares ◽  
Benjamin Fasoli ◽  
Corbin Anderson ◽  
...  
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
Low Income ◽  
Urban Areas ◽  
Salt Lake ◽  
Fine Particulate Matter ◽  
Salt Lake City ◽  
Outdoor Air ◽  
Lake City ◽  
Indoor And Outdoor

Every day around 93% of children under the age of 15 (1.8 billion children) breathe outdoor air that is so polluted it puts their health and development at serious risk. Due to the pandemic, however, ventilation of buildings using outdoor air has become an important safety technique to prevent the spread of COVID-19. With the mounting ev-idence suggesting that air pollution is impactful to human health and educational out-comes, this contradictory guidance may be problematic in schools with higher air pol-lution levels, but keeping kids COVID-19 free and in school to receive their education is now more pressing than ever. To understand if all schools in an urban area are ex-posed to similar outdoor air quality and if school infrastructure protects children equally indoors, we installed research grade sensors to observe PM2.5 concentrations in indoor and outdoor settings to understand how unequal exposure to indoor and out-door air pollution impacts indoor air quality among high- and low-income schools in Salt Lake City, Utah. Based on this approach, we found that during atmospheric inver-sions and dust events, there was a lag ranging between 35 to 73 minutes for the out-door PM2.5 concentrations to follow a similar temporal pattern as the indoor PM2.5. This lag has policy and health implications and may help to explain the rising concerns re-garding reduced educational outcomes related to air pollution in urban areas. These data and resulting analysis show that poor air quality may impact school settings, and the potential implications with respect to environmental inequality.

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