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Ozone

Description: The term "ozone depletion" means more than just the natural destruction of ozone, it means that ozone loss is exceeding ozone creation.
Date: 2002
Creator: NASA Earth Observatory
Partner: UNT Libraries

Ozone

Description: The amount and distribution of ozone molecules in the stratosphere varies greatly over the globe. Ozone molecules are transported around the stratosphere much as water clouds are transported in the troposphere. Therefore, scientists observing ozone fluctuations over just one spot could not know whether a change in local ozone levels meant an alteration in global ozone levels, or simply a fluctuation in the concentration over that particular spot. Satellites have given scientists the ability to overcome this problem because they provide a picture of what is happening daily over the entire Earth.
Date: 2002
Creator: NASA Earth Observatory
Partner: UNT Libraries

Ozone

Description: In the stratosphere, ozone is created primarily by ultraviolet radiation. When high-energy ultraviolet rays strike ordinary oxygen molecules (O2), they split the molecule into two single oxygen atoms, known as atomic oxygen. A freed oxygen atom then combines with another oxygen molecule to form a molecule of ozone. There is so much oxygen in our atmosphere, that these high-energy ultraviolet rays are completely absorbed in the stratosphere.
Date: 2002
Creator: NASA Earth Observatory
Partner: UNT Libraries

Automated Low-cost Instrument for Measuring Total Column Ozone

Description: Networks of ground-based and satellite borne instruments to measure ultraviolet (UV) sunlight and total column ozone have greatly contributed to an understanding of increased amounts of UV reaching the surface of the Earth caused by stratospheric ozone depletion. Increased UV radiation has important potential effects on human health, and agricultural and ecological systems. Observations from these networks make it possible to monitor total ozone decreases and to predict ozone recovery trends due to global efforts to curb the use of products releasing chemicals harmful to the ozone layer. Thus, continued and expanded global monitoring of ozone and UV is needed. However, existing automatic stratospheric ozone monitors are complex and expensive instruments. The main objective of this research was the development of a low-cost fully automated total column ozone monitoring instrument which, because of its affordability, will increase the number of instruments available for ground-based observations. The new instrument is based on a high-resolution fiber optic spectrometer, coupled with fiber optics that are precisely aimed by a pan and tilt positioning mechanism and with controlling programs written in commonly available software platforms which run on a personal computer. This project makes use of novel low-cost fiber optic spectrometer technology. A cost advantage is gained over available units by placing one end of the fiber outdoors to collect sunlight and convey it indoors, thereby allowing the spectrometer and computer to be placed in a controlled environment. This reduces the cost of weatherproofing and thermal compensation. Cost savings also result from a simplified sun targeting system, because only a small pan and tilt device is required to aim the lightweight fiber optic ends. Precision sun-targeting algorithms, optical filter selection, and software to derive ozone from spectral measurements by the spectrometer are a major contribution of this project. This system is a flexible platform ...
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Date: May 2006
Creator: Nebgen, Gilbert Bernard
Partner: UNT Libraries

A study of the impact of unconventional sources within a large urban area: Evidence from spatio-temporal assessment of volatile organic compounds.

Description: Conventional sources of emissions have been a prime target for policymakers in designing pollution control strategies. However, the evolution of shale gas activities is a growing concern over the impact of unconventional sources on urban and regional air quality. Owing to the development of Barnett Shale production, the fast-growing Dallas-Fort Worth (DFW) metroplex has encountered both types of these emissions. Oil and gas activities result in emissions of ozone precursors, notably volatile organic compounds (VOC). The major objective of this study was to evaluate the spatio-temporal distribution of VOC in order to highlight the influence of unconventional emissions. The study utilized measurements from automated gas chromatography (AutoGC) monitors to analyze the patterns of the total non-methane organic compounds (TNMOC) and relative contributions from marker species of traffic versus oil and gas activities. In this study, data from 2001-2014 was obtained from the Texas Commission on Environmental Quality (TCEQ) for fifteen monitoring sites within the North Texas region. With over a thousand wells in a 10 mile radius, two of the rural sites measured twice as much TNMOC as compared to the urban site in Dallas. Source apportionment analysis was conducted using Positive Matrix Factorization (PMF) technique. The target site located in the urban zone resolved an eight factor model. Natural gas signature was the dominant source of emission with a 52% contribution followed by 31% from two separate traffic-related sources. Considering ethane to be the dominant species in oil and gas emissions, it was observed that the rising ethane/NOx ratio correlated with increasing annual average ozone post-2007. In this period, higher concentration of ozone was found to be associated with stronger winds from the Barnett Shale area – a region that did not seem to contribute to high ozone during 2001-2007. With traffic emissions having flattened over the years, the ...
Date: May 2016
Creator: Matin, Maleeha
Partner: UNT Libraries

EPA's 20115 Ozone Air Quality Standards

Description: This report discusses the EPA's standard-setting process for National Ambient Air Quality Standards (NAAQS), the specifics of the most recent reviews, and issues raised by the 2015 rulemaking, which lowered the allowed levels of ozone pollution in the air, and its implementation.
Date: August 15, 2017
Creator: McCarthy, James E. & Lattanzio, Richard K.
Partner: UNT Libraries Government Documents Department

Ozone

Description: Although it represents only a tiny fraction of the atmosphere, ozone is crucial for life on Earth. Depending on where ozone resides, it can protect or harm life on Earth.
Date: 2002
Creator: NASA Earth Observatory
Partner: UNT Libraries

Safeguarding the Ozone Layer and the Global Climate System: Issues related to hydrofluorocarbons and perfluorocarbons

Description: This Special Report on Safeguarding the Ozone and the Global Climate System has been developed in response to invitations from Parties to the UNFCCC and the Montreal Protocol. It provides information relevant to decision-making in regard to safeguarding the ozone layer and the global climate system: two global environmental issues involving complex scientific and technical considerations.
Date: 2005
Creator: Intergovernmental Panel on Climate Change
Partner: UNT Libraries

Reconstruction and Prediction of Variations of Total Ozone and Associated Variations of UV-B Solar Radiation for Subarctic Regions Based of Dendrochronologic Data

Description: Variations of dendrochronologic parameters, especially annual ring density, significantly reflect the physiological tree response to systematic variations of solar UV-B radiation, taking place on monthly and longer timescales during growing season. Such variations of UV-B radiation are totally governed by variations of total ozone (TO). Thus, in any dendrochronologic signal, especially for coniferous trees, there is also a recorded response to TO variations, characterizing variations of UV-B radiation. Because a monitoring of global TO distribution is regularly performed since 1979 using TOMS satellite instrumentation, there appears a possibility to reconstruct TO behavior in the past practically at any point of dendrochronologic monitoring network. The reconstruction is performed by the method of linear regression, based on significant correlation of annual ring density of coniferous trees and TO for coordinates of denrochronologic signal. The present report considers the Subarctic latitudes, which are characterized by considerable TO variations in the second half of twentieth century.
Date: March 18, 2005
Creator: Zuev, V.V. & Bondarenko, S.L.
Partner: UNT Libraries Government Documents Department

Modeling analysis of the impact of anthropogenic emission sources on ozone concentration over selected urban areas in Texas

Description: This article discusses a regional photochemical modeling experiment set up to simulate a high ozone episode of September 11-14, 2002 to evaluate the impact of various anthropogenic emissions sources on ozone concentrations.
Date: September 9, 2012
Creator: Farooqui, Zuber M.; John, Kuruvilla; Biswas, Jhumoor & Sule, Neelesh
Partner: UNT College of Engineering

Air Quality and the New Ozone NAAQS: The OTAG Process

Description: The Ozone Transport Assessment Group (OTAG) represented a cooperative effort between states, the Environmental Protection Agency (EPA), and numerous stakeholders to address teh complex issue of ozone transport. However, opponents of the new ozone National Ambient Air Quality Standard (NAAQS) argue that the OTAG recommendations are far too vague and ambiguous to be cited by EPA as a basis for implementation. This report provides background on the effort, and summarizes OTAG's assessment and recommendations.
Date: July 30, 1998
Creator: Parker, Larry & Blodgett, John E.
Partner: UNT Libraries Government Documents Department

Ozone Reactions in Aqueous Solutions: a Bibliography

Description: Abstract: A reaction oriented list of references is provided for published papers and reports containing rate data or information on mechanism for reactions of ozone with various substrates in aqueous solutions. Catalyzed, as well as uncatalyzed, reactions are included. One hundred and sixty-four papers are listed. The period covered extends from 1913 to 1981.
Date: August 1983
Creator: Westley, Francis
Partner: UNT Libraries Government Documents Department

Measuring Atmospheric Ozone and Nitrogen Dioxide Concentration by Differential Optical Absorption Spectroscopy

Description: The main objective was to develop a procedure based on differential optical absorption spectroscopy (DOAS) to measure atmospheric total column of ozone, using the automated instrument developed at the University of North Texas (UNT) by Nebgen in 2006. This project also explored the ability of this instrument to provide measurements of atmospheric total column nitrogen dioxide. The instrument is located on top of UNT’s Environmental Education, Science and Technology Building. It employs a low cost spectrometer coupled with fiber optics, which are aimed at the sun to collect solar radiation. Measurements taken throughout the day with this instrument exhibited a large variability. The DOAS procedure derives total column ozone from the analysis of daily DOAS Langley plots. This plot relates the measured differential column to the airmass factor. The use of such plots is conditioned by the time the concentration of ozone remains constant. Observations of ozone are typically conducted throughout the day. Observations of total column ozone were conducted for 5 months. Values were derived from both DOAS and Nebgen’s procedure and compared to satellite data. Although differences observed from both procedures to satellite data were similar, the variability found in measurements was reduced from 70 Dobson units, with Nebgen’s procedure, to 4 Dobson units, with the DOAS procedure.A methodology to measure atmospheric nitrogen dioxide using DOAS was also investigated. Although a similar approach to ozone measurements could be applied, it was found that such measurements were limited by the amount of solar radiation collected by the instrument. Observations of nitrogen dioxide are typically conducted near sunrise or sunset, when solar radiation experiences most of the atmospheric absorption.
Date: December 2011
Creator: Jerez, Carlos J.
Partner: UNT Libraries

Photodissociation of ozone at 276nm by photofragment imaging and high resolution photofragment translational spectroscopy

Description: The photodissociation of ozone at 276 nm is investigated using both state resolved ion imaging and high-resolution photofragment translational spectroscopy. Ion images from both [3+1] and [2+1] resonance enhanced multiphoton ionization of the O({sup 1}D) photofragment are reported. All images show strong evidence of O({sup 1}D) orbital alignment. Photofragment translation spectroscopy time-of-flight spectra are reported for the O{sub 2} ({sup 1}{Delta}{sub g}) photofragment. Total kinetic energy release distributions determined form these spectra are generally consistent with those distributions determined from imaging data. Observed angular distributions are reported for both detection methods, pointing to some unresolved questions for ozone dissociation in this wavelength region.
Date: November 1, 1996
Creator: Blunt, D.A. & Suits, A.G.
Partner: UNT Libraries Government Documents Department

Carbon Dioxide Analysis Center and World Data Center-A for Atmospheric Trace Gases fiscal year 1997 annual report

Description: Fiscal year (FY) 1997 was another exciting and productive one for the Carbon Dioxide Information Analysis Center (CDIAC) at the Oak Ridge National Laboratory. During FY 1997, CDIAC launched the Quality Systems Science Center for the North American Research Strategy for Tropospheric Ozone (NARSTO). The purpose of NARSTO--a US-Canada-Mexico initiative of government agencies, industry, and the academic research community--is to improve the understanding of the formation and transport of tropospheric ozone.
Date: March 1, 1998
Creator: Burtis, M.D.; Cushman, R.M.; Boden, T.A.; Jones, S.B.; Kaiser, D.P. & Nelson, T.R.
Partner: UNT Libraries Government Documents Department

SAGE II/Umkehr ozone comparisons and aerosols effects: An empirical and theoretical study. Final report

Description: The objectives of this research were to: (1) examine empirically the aerosol effect on Umkehr ozone profiles using SAGE II aerosol and ozone data; (2) examine theoretically the aerosol effect on Umkehr ozone profiles; (3) examine the differences between SAGE II ozone profiles and both old- and new-format Umkehr ozone profiles for ozone-trend information; (4) reexamine SAGE I-Umkehr ozone differences with the most recent version of SAGE I data; and (5) contribute to the SAGE II science team.
Date: September 15, 1997
Creator: Newchurch, M.
Partner: UNT Libraries Government Documents Department