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Donald J Wuebbles - One of the best experts on this subject based on the ideXlab platform.
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oh reaction rate constant ir absorption spectrum ozone depletion potentials and global warming potentials of 2 bromo 3 3 3 trifluoropropene
Journal of Geophysical Research, 2011Co-Authors: Kenneth O Patten, Vladimir L Orkin, Victor G Khamaganov, Steven L Baughcum, Donald J WuebblesAbstract:[1] The rate constant for the gas phase reaction of OH radicals with BTP (2-bromo-3,3,3-trifluoropropene, CH2 = CBrCF3) was measured using a flash photolysis resonance-fluorescence technique over the temperature range 220 K to 370 K. The Arrhenius plot was found to exhibit noticeable curvature. The temperature dependence of the rate constant can be represented askBTP(220 − 370 K) = 4.85 × 10−13 × (T/298)0.92 × exp{+613/T} cm3 molecule−1 s−1. For Atmospheric modeling purposes, kBTP(T) can be equally well represented by the standard Arrhenius expression kBTP(220 − 298 K) = 1.05 × 10−12 × exp{+381/T} cm3 molecule−1 s−1. The IR absorption cross-sections of BTP were also measured between 450 cm−1 and 1900 cm−1. BTP Atmospheric Lifetime, Ozone Depletion Potential (ODP), and Global Warming Potential (GWP) were evaluated in the Whole Atmosphere Community Climate Model for land emissions from 30 to 60°N and from 60°S to 60°N. The global, annual average Atmospheric Lifetime of BTP in the former scenario was 7.0 days, its ODP was 0.0028, and its GWP (100-yr time horizon) was 0.0050; in the latter scenario, the global, annual average BTP Lifetime was 4.3 days, ODP was 0.0052, and 100-yr GWP was 0.0028. The short Lifetime, low ODP, and low GWP indicate that BTP should have minimal effects on ozone and climate. Little BTP reaches the stratosphere in either emission scenario, but 27% of the ozone loss in the 30 to 60°N scenario and 46% of the ozone loss in the 60°S to 60°N scenario occurs above the tropopause due to Bry from BTP.
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Atmospheric Lifetimes and ozone depletion potentials of trans-1-chloro-3,3,3-trifluoropropylene and trans-1,2-dichloroethylene in a three-dimensional model
Atmospheric Chemistry and Physics, 2010Co-Authors: Kenneth O Patten, Donald J WuebblesAbstract:Abstract. The chloroalkenes trans-1-chloro-3,3,3-trifluoropropylene (tCFP) and trans-1,2-dichloroethylene (tDCE) have been proposed as candidate replacements for other compounds in current use that cause concerns regarding potential environmental effects including destruction of stratospheric ozone. Because tCFP and tDCE contain chlorine atoms, the effects of these short-lived compounds on stratospheric ozone must be established. In this study, we derive the Atmospheric Lifetimes and Ozone Depletion Potentials (ODPs) for tCFP and for tDCE assuming emissions from land surfaces at latitudes 30° N to 60° N using the MOZART 3 three-dimensional model of Atmospheric chemistry and physics. 53% of the ozone loss due to tCFP and 98% of the ozone loss due to tDCE take place in the troposphere, rather than in the stratosphere as generally expected from longer-lived chlorocarbons. The Atmospheric Lifetime of tCFP against chemical reaction is 40.4 days, and its ODP is quite small at 0.00034. The tDCE Atmospheric Lifetime is 12.7 days, and its ODP is 0.00024, which is the lowest ODP found for any chlorocarbon we have studied. Our study suggests that chlorine from tCFP and tDCE are unlikely to affect ozone at quantities likely to be emitted to the atmosphere.
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Evaluation of the Atmospheric Lifetime and radiative forcing on climate for 1,2,2,2-Tetrafluoroethyl Trifluoromethyl ether (CF3OCHFCF3)
Journal of Geophysical Research: Atmospheres, 2001Co-Authors: Atul K. Jain, Donald J Wuebbles, Vaishali Naik, David A. Good, Jaron C. Hansen, Joseph S. FranciscoAbstract:The compound 1,2,2,2-Tetrafluoroethyl Trifluoromethyl Ether, CF3OCHFCF3 (HFE-227), is currently being considered as a potential replacement for certain halocarbons, particularly for perfluorocarbons (PFCs), as a dry etching gas in the semiconductor industry. For this reason, it is important to determine the potential environmental effects resulting from the use and emissions of this compound. In this paper, the Atmospheric Lifetime, radiative forcing, and Global Warming Potentials (GWPs), an important measure of the potential effects of a gas on climate, are evaluated for this compound using our zonally averaged chemical transport and radiative transfer models of the atmosphere. To our knowledge, this is the first time this compound has been evaluated with such Atmospheric models. In order to calculate the Lifetime and radiative forcing, the rate constants and infrared cross sections of this compound were measured in laboratories at Illinois and Purdue, and results are reported here. The model-evaluated Atmospheric Lifetime is 11.3 years, mainly due to reaction with OH radicals. The model-evaluated instantaneous-clear-sky radiative forcing is 0.38 W m−2 ppbv−1, about 45% lower than previously estimated [Imasu et al., 1995]. However, the model-estimated cloudy-sky adjusted forcing, needed to calculated GWPs, is about 25% lower than the model-estimated instantaneous-clear-sky forcing. The GWPs are calculated to be 3400, 1200, and 370 for 20, 100, and 500 year time horizons, respectively.
James B. Burkholder - One of the best experts on this subject based on the ideXlab platform.
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cbrf3 halon 1301 uv absorption spectrum between 210 and 320k Atmospheric Lifetime and ozone depletion potential
Journal of Photochemistry and Photobiology A-chemistry, 2015Co-Authors: Eric L. Fleming, Max R. Mcgillen, Charles H. Jackman, Francois Bernard, James B. BurkholderAbstract:Abstract CBrF3 (Halon-1301) is a man-made ozone depleting substance that is a major source of bromine in the Earth’s stratosphere. Halon-1301 is predominantly removed from the atmosphere by UV photolysis in the stratosphere at wavelengths between 200 and 225 nm. The existing level of uncertainty in the Halon-1301 UV absorption spectrum temperature-dependence directly impacts the ability to model stratospheric ozone chemistry and climate change. In this work, the UV absorption spectrum of Halon-1301 between 195 and 235 nm was measured over the temperature range 210–320 K. An empirical parameterization of the spectrum and its temperature dependence is presented. The present results are critically compared with results from previous studies and the current recommendation for use in Atmospheric models. A global annually averaged Lifetime for Halon-1301 of 74.6 (73.7–75.5) years was calculated using a 2-D Atmospheric model and the present results. The range of Lifetimes given in parenthesis represents the possible values due solely to the 2σ uncertainty in the Halon-1301 UV spectrum obtained in this work. In addition, the CBrF3 ozone depletion potential was calculated using the 2-D model to be 18.6 (±0.1) using the UV spectrum and 2σ uncertainty from this work.
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CFCI3 (CFC-11): UV Absorption Spectrum Temperature Dependence Measurements and the Impact on Atmospheric Lifetime and Uncertainty
Geophysical Research Letters, 2013Co-Authors: Max R. Mcgillen, Eric L. Fleming, Charles H. Jackman, James B. BurkholderAbstract:[1] CFCl3 (CFC-11) is both an Atmospheric ozone-depleting and potent greenhouse gas that is removed primarily via stratospheric UV photolysis. Uncertainty in the temperature dependence of its UV absorption spectrum is a significant contributing factor to the overall uncertainty in its global Lifetime and, thus, model calculations of stratospheric ozone recovery and climate change. In this work, the CFC-11 UV absorption spectrum was measured over a range of wavelength (184.95–230 nm) and temperature (216–296 K). We report a spectrum temperature dependence that is less than that currently recommended for use in Atmospheric models. The impact on its Atmospheric Lifetime was quantified using a 2-D model and the spectrum parameterization developed in this work. The calculated global annually averaged Lifetime was 58.1 ± 0.7 years (2σ uncertainty due solely to the spectrum uncertainty). The Lifetime is slightly reduced and the uncertainty significantly reduced from that obtained using current UV spectrum recommendations.
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Atmospheric Lifetime of CHF2Br, a Proposed Substitute for Halons.
Science (New York N.Y.), 1991Co-Authors: Ranajit K. Talukdar, Abdelwahid Mellouki, Tomasz Gierczak, James B. Burkholder, Stuart A. Mckeen, A. R. RavishankaraAbstract:The rate coefficients, k{sub 1}, for the reaction of OH with CHF{sub 2}Br have been measured using pulsed photolysis and discharge flow techniques at temperatures (T) between 233 and 432 K to be k{sub 1} = (7.4 {plus minus} 1.6) {times} 10{sup {minus}13} exp({minus}(1,300 {plus minus} 100)/T) cubic centimeters per molecule per second. The ultraviolet absorption cross sections, {sigma}, of this molecule between 190 and 280 nanometers were measured at 296 K. The k{sub 1} and {sigma} values were used in a one-dimensional model to obtain an Atmospheric Lifetime of approximately 7 years for CHF{sub 2}Br. This Lifetime is shorter by approximately factors of 10 and 2 than those for CF{sub 3}Br and CF{sub 2}ClBr, respectively. The ozone depletion potentials of the three compounds will reflect these Lifetimes.
Kenneth O Patten - One of the best experts on this subject based on the ideXlab platform.
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oh reaction rate constant ir absorption spectrum ozone depletion potentials and global warming potentials of 2 bromo 3 3 3 trifluoropropene
Journal of Geophysical Research, 2011Co-Authors: Kenneth O Patten, Vladimir L Orkin, Victor G Khamaganov, Steven L Baughcum, Donald J WuebblesAbstract:[1] The rate constant for the gas phase reaction of OH radicals with BTP (2-bromo-3,3,3-trifluoropropene, CH2 = CBrCF3) was measured using a flash photolysis resonance-fluorescence technique over the temperature range 220 K to 370 K. The Arrhenius plot was found to exhibit noticeable curvature. The temperature dependence of the rate constant can be represented askBTP(220 − 370 K) = 4.85 × 10−13 × (T/298)0.92 × exp{+613/T} cm3 molecule−1 s−1. For Atmospheric modeling purposes, kBTP(T) can be equally well represented by the standard Arrhenius expression kBTP(220 − 298 K) = 1.05 × 10−12 × exp{+381/T} cm3 molecule−1 s−1. The IR absorption cross-sections of BTP were also measured between 450 cm−1 and 1900 cm−1. BTP Atmospheric Lifetime, Ozone Depletion Potential (ODP), and Global Warming Potential (GWP) were evaluated in the Whole Atmosphere Community Climate Model for land emissions from 30 to 60°N and from 60°S to 60°N. The global, annual average Atmospheric Lifetime of BTP in the former scenario was 7.0 days, its ODP was 0.0028, and its GWP (100-yr time horizon) was 0.0050; in the latter scenario, the global, annual average BTP Lifetime was 4.3 days, ODP was 0.0052, and 100-yr GWP was 0.0028. The short Lifetime, low ODP, and low GWP indicate that BTP should have minimal effects on ozone and climate. Little BTP reaches the stratosphere in either emission scenario, but 27% of the ozone loss in the 30 to 60°N scenario and 46% of the ozone loss in the 60°S to 60°N scenario occurs above the tropopause due to Bry from BTP.
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Atmospheric Lifetimes and ozone depletion potentials of trans-1-chloro-3,3,3-trifluoropropylene and trans-1,2-dichloroethylene in a three-dimensional model
Atmospheric Chemistry and Physics, 2010Co-Authors: Kenneth O Patten, Donald J WuebblesAbstract:Abstract. The chloroalkenes trans-1-chloro-3,3,3-trifluoropropylene (tCFP) and trans-1,2-dichloroethylene (tDCE) have been proposed as candidate replacements for other compounds in current use that cause concerns regarding potential environmental effects including destruction of stratospheric ozone. Because tCFP and tDCE contain chlorine atoms, the effects of these short-lived compounds on stratospheric ozone must be established. In this study, we derive the Atmospheric Lifetimes and Ozone Depletion Potentials (ODPs) for tCFP and for tDCE assuming emissions from land surfaces at latitudes 30° N to 60° N using the MOZART 3 three-dimensional model of Atmospheric chemistry and physics. 53% of the ozone loss due to tCFP and 98% of the ozone loss due to tDCE take place in the troposphere, rather than in the stratosphere as generally expected from longer-lived chlorocarbons. The Atmospheric Lifetime of tCFP against chemical reaction is 40.4 days, and its ODP is quite small at 0.00034. The tDCE Atmospheric Lifetime is 12.7 days, and its ODP is 0.00024, which is the lowest ODP found for any chlorocarbon we have studied. Our study suggests that chlorine from tCFP and tDCE are unlikely to affect ozone at quantities likely to be emitted to the atmosphere.
Max R. Mcgillen - One of the best experts on this subject based on the ideXlab platform.
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cbrf3 halon 1301 uv absorption spectrum between 210 and 320k Atmospheric Lifetime and ozone depletion potential
Journal of Photochemistry and Photobiology A-chemistry, 2015Co-Authors: Eric L. Fleming, Max R. Mcgillen, Charles H. Jackman, Francois Bernard, James B. BurkholderAbstract:Abstract CBrF3 (Halon-1301) is a man-made ozone depleting substance that is a major source of bromine in the Earth’s stratosphere. Halon-1301 is predominantly removed from the atmosphere by UV photolysis in the stratosphere at wavelengths between 200 and 225 nm. The existing level of uncertainty in the Halon-1301 UV absorption spectrum temperature-dependence directly impacts the ability to model stratospheric ozone chemistry and climate change. In this work, the UV absorption spectrum of Halon-1301 between 195 and 235 nm was measured over the temperature range 210–320 K. An empirical parameterization of the spectrum and its temperature dependence is presented. The present results are critically compared with results from previous studies and the current recommendation for use in Atmospheric models. A global annually averaged Lifetime for Halon-1301 of 74.6 (73.7–75.5) years was calculated using a 2-D Atmospheric model and the present results. The range of Lifetimes given in parenthesis represents the possible values due solely to the 2σ uncertainty in the Halon-1301 UV spectrum obtained in this work. In addition, the CBrF3 ozone depletion potential was calculated using the 2-D model to be 18.6 (±0.1) using the UV spectrum and 2σ uncertainty from this work.
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CFCI3 (CFC-11): UV Absorption Spectrum Temperature Dependence Measurements and the Impact on Atmospheric Lifetime and Uncertainty
Geophysical Research Letters, 2013Co-Authors: Max R. Mcgillen, Eric L. Fleming, Charles H. Jackman, James B. BurkholderAbstract:[1] CFCl3 (CFC-11) is both an Atmospheric ozone-depleting and potent greenhouse gas that is removed primarily via stratospheric UV photolysis. Uncertainty in the temperature dependence of its UV absorption spectrum is a significant contributing factor to the overall uncertainty in its global Lifetime and, thus, model calculations of stratospheric ozone recovery and climate change. In this work, the CFC-11 UV absorption spectrum was measured over a range of wavelength (184.95–230 nm) and temperature (216–296 K). We report a spectrum temperature dependence that is less than that currently recommended for use in Atmospheric models. The impact on its Atmospheric Lifetime was quantified using a 2-D model and the spectrum parameterization developed in this work. The calculated global annually averaged Lifetime was 58.1 ± 0.7 years (2σ uncertainty due solely to the spectrum uncertainty). The Lifetime is slightly reduced and the uncertainty significantly reduced from that obtained using current UV spectrum recommendations.
A. R. Ravishankara - One of the best experts on this subject based on the ideXlab platform.
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Multiphase chemistry of NO3 in the remote troposphere
Journal of Geophysical Research: Atmospheres, 1998Co-Authors: Yinon Rudich, Ranajit K. Talukdar, A. R. RavishankaraAbstract:The effect of NO3 uptake at night into marine aerosol and cloud droplets on (1) sulfur oxidation, (2) NO3 ambient concentrations, and (3) NO3 Atmospheric Lifetime is examined using a simple chemical kinetics model. It is shown that the Atmospheric Lifetime toward multiphase removal of NO3 is < 10 min in presence of cloud droplets. We also show that at low mixing ratios of H2O2 (
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Atmospheric Lifetime, its application and its determination: CFC-substitutes as a case study
Journal of the Chemical Society Faraday Transactions, 1994Co-Authors: A. R. Ravishankara, Edward R. LovejoyAbstract:The concept of Atmospheric Lifetime, its application in Atmospheric chemistry, and its use in defining environmental acceptability indices such as the ozone depletion potential and the global warming potential are described. The determination of the Atmospheric Lifetime from laboratory measured chemical kinetic and photochemical parameters is highlighted. A brief description of the laboratory methods used to determine kinetic parameters and the difficulties encountered in measuring them are given. In all these descriptions and discussions, chlorofluorocarbons (CFCs) and their substitutes are used as examples. The environmental acceptability of the currently proposed CFC substitutes, the hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) are discussed. Lastly, the question is raised: Should Atmospheric Lifetime be used as an index of acceptability?
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Rate coefficients for reactions of several hydrofluorocarbons with hydroxyl and oxygen atom(1D) and their Atmospheric Lifetimes
The Journal of Physical Chemistry, 1993Co-Authors: A. M. Schmoltner, Ranajit K. Talukdar, Abdelwahid Mellouki, Tomasz Gierczak, Stuart A. Mckeen, R. F. Warren, Leah Goldfarb, A. R. RavishankaraAbstract:The rate coefficients for the reaction of OH with CH 3 F, CHF 3 , C 2 H 5 F, C 4 H 2 F 8 , and C 5 H 2 F 10 were measured at temperatures between 232 and 378 K using the pulsed laser photolysis-laser-induced fluorescence technique. The rate coefficients for the reaction of O( 1 D) with the above molecules and CH 2 F 2 were measured at room temperature using time-resolved vacuum-UV atomic resonance fluorescence detection of O( 3 P). The Atmospheric Lifetime needed for the evaluation of global warming potentials were calculated for all six molecules using a one-dimensional Atmospheric model using the kinetic data obtained in the present study
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Atmospheric Lifetime of CHF2Br, a Proposed Substitute for Halons.
Science (New York N.Y.), 1991Co-Authors: Ranajit K. Talukdar, Abdelwahid Mellouki, Tomasz Gierczak, James B. Burkholder, Stuart A. Mckeen, A. R. RavishankaraAbstract:The rate coefficients, k{sub 1}, for the reaction of OH with CHF{sub 2}Br have been measured using pulsed photolysis and discharge flow techniques at temperatures (T) between 233 and 432 K to be k{sub 1} = (7.4 {plus minus} 1.6) {times} 10{sup {minus}13} exp({minus}(1,300 {plus minus} 100)/T) cubic centimeters per molecule per second. The ultraviolet absorption cross sections, {sigma}, of this molecule between 190 and 280 nanometers were measured at 296 K. The k{sub 1} and {sigma} values were used in a one-dimensional model to obtain an Atmospheric Lifetime of approximately 7 years for CHF{sub 2}Br. This Lifetime is shorter by approximately factors of 10 and 2 than those for CF{sub 3}Br and CF{sub 2}ClBr, respectively. The ozone depletion potentials of the three compounds will reflect these Lifetimes.
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new measurement of the rate coefficient for the reaction of oh with methane
Nature, 1991Co-Authors: Ghanshyam L Vaghjiani, A. R. RavishankaraAbstract:METHANE is an important greenhouse gas, whose concentration in the troposphere is steadily increasing. To estimate the flux of methane into the atmosphere and its Atmospheric Lifetime, its rate of removal needs to be accurately determined. The main loss process for Atmospheric methane is the reaction with the hydroxyl radical OH. We have measured the rate coefficient for this reaction in carefully controlled experiments and found it to be smaller than currently accepted values. Our results indicate a longer CH4 Lifetime (by ∼25%) and a correspondingly smaller flux (by ∼100 Tg CH4 yr−1) than previously calculated.