scholarly journals Atmospheric lifetimes and ozone depletion potentials of trans-1-chloro-3,3,3-trifluoropropylene and trans-1,2-dichloroethylene in a three-dimensional model

2010 ◽  
Vol 10 (7) ◽  
pp. 16637-16657 ◽  
Author(s):  
K. O. Patten ◽  
D. J. Wuebbles

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. Both tCFP and tDCE are shown to primarily affect ozone 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 significantly affect ozone at quantities likely to be emitted to the atmosphere.

2010 ◽  
Vol 10 (22) ◽  
pp. 10867-10874 ◽  
Author(s):  
K. O. Patten ◽  
D. J. Wuebbles

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.


2011 ◽  
Vol 11 (5) ◽  
pp. 2371-2380 ◽  
Author(s):  
D. J. Wuebbles ◽  
K. O. Patten ◽  
D. Wang ◽  
D. Youn ◽  
M. Martínez-Avilés ◽  
...  

Abstract. The existing solvents trichloroethylene (TCE) and perchloroethylene (PCE) and proposed solvent n-propyl bromide (nPB) have atmospheric lifetimes from days to a few months, but contain chlorine or bromine that could affect stratospheric ozone. Several previous studies estimated the Ozone Depletion Potentials (ODPs) for various assumptions of nPB emissions location, but these studies used simplified modeling treatments. The primary purpose of this study is to reevaluate the ODP for n-propyl bromide (nPB) using a current-generation chemistry-transport model of the troposphere and stratosphere. For the first time, ODPs for TCE and PCE are also evaluated in a three-dimensional, global atmospheric chemistry-transport model. Emissions representing industrial use of each compound are incorporated on land surfaces from 30° N to 60° N. The atmospheric chemical lifetime obtained for nPB is 24.7 days, similar to past literature, but the ODP is 0.0049, lower than in our past study of nPB. The derived atmospheric lifetime for TCE is 13.0 days and for PCE is 111 days. The corresponding ODPs are 0.00037 and 0.0050, respectively.


2010 ◽  
Vol 10 (7) ◽  
pp. 17889-17910 ◽  
Author(s):  
D. J. Wuebbles ◽  
K. O. Patten ◽  
D. Wang ◽  
D. Youn ◽  
M. Martínez-Avilés ◽  
...  

Abstract. The existing solvents trichloroethylene (TCE) and perchloroethylene (PCE) and proposed solvent n-propyl bromide (nPB) have atmospheric lifetimes from days to a few months, but contain chlorine or bromine that could affect stratospheric ozone. Several previous studies estimated the Ozone Depletion Potentials (ODPs) for various assumptions for location of nPB emissions, but these studies used simplified modeling treatments. The primary purpose of this study is to reevaluate the ODP for nPB using a current-generation chemistry-transport model of the troposphere and stratosphere. For the first time, ODPs for TCE and PCE are also evaluated. Emissions representing industrial use of each compound are incorporated on land surfaces from 30° N to 60° N. The atmospheric chemical lifetime obtained for nPB is 24.7 days, similar to past literature, but the ODP is 0.0049, lower than in past studies. The derived atmospheric lifetime for TCE is 13.0 days and for PCE is 111 days. The corresponding ODPs are 0.00035 and 0.0060, respectively.


2010 ◽  
Vol 10 (7) ◽  
pp. 16659-16690
Author(s):  
◽  
K. O. Patten ◽  
D. J. Wuebbles ◽  
◽  

Abstract. The concept of Ozone Depletion Potentials (ODPs) is extensively used in policy considerations related to concerns about the effects of various halocarbons and other gases on stratospheric ozone. Many of the recent candidate replacement compounds have atmospheric lifetimes shorter than one year in order to limit their environmental effects, especially on stratospheric ozone. Using a three-dimensional global chemistry-transport model (CTM) of the troposphere and the stratosphere, the purpose of this study is to evaluate the potential effects of several very short-lived iodinated substances, namely iodotrifluoromethane (CF3I) and methyl iodide (CH3I), on atmospheric ozone. Like other chemicals with extremely short lifetimes, the stratospheric halogen loading and resulting ozone effects from these compounds are strongly dependent on the location of emissions. For CF3I, a possible replacement candidate for bromotrifluoromethane (CF3Br), ODPs derived by the three-dimensional model are 0.008 with chemical lifetime of 5.03 days and 0.016 with a lifetime of 1.13 days for emissions assumed to be evenly distributed over land surfaces at mid-latitudes and the tropics, respectively. While this is the first time the ODPs have been evaluated with a three-dimensional model, these values are in good agreement with those derived previously. The model calculations suggest that tropical convection could deliver a larger portion of the gas and their breakdown products to the upper troposphere and lower stratosphere if emission source is located in the tropics. The resulting ODP for CH3I, emitted from mid-latitudes, is 0.017 with lifetime of 13.59 days. The validity of our model iodine chemistry to evaluate ODPs of the iodine species is guaranteed with good qualitative agreement between the model derived distribution of background CH3I, based on global source emission fluxes from previous studies, and available observations especially in vertical profiles.


2001 ◽  
Vol 19 (9) ◽  
pp. 1163-1181 ◽  
Author(s):  
J. Hendricks ◽  
F. Baier ◽  
G. Günther ◽  
B. C. Krüger ◽  
A. Ebel

Abstract. The sensitivity of modelled ozone depletion in the winter Arctic stratosphere to different assumptions of prevalent PSC types and PSC formation mechanisms is investigated. Three-dimensional simulations of the winter 1995/96 are performed with the COlogne Model of the Middle Atmosphere (COMMA) by applying different PSC microphysical schemes. Model runs are carried out considering either liquid or solid PSC particles or a combined microphysical scheme. These simulations are then compared to a model run which only takes into account binary sulfate aerosols. The results obtained with the three-dimensional model agree with trajectory-box simulations performed in previous studies. The simulations suggest that conditions appropriate for type Ia PSC existence (T < TNAT ) occur over longer periods and cover larger areas when compared to conditions of potential type Ib PSC existence. Significant differences in chlorine activation and ozone depletion occur between the simulations including only either liquid or solid PSC particles. The largest differences, occurring over large spatial scales and during prolonged time periods, are modelled first, when the stratospheric temperatures stay below TNAT , but above the threshold of effective liquid particle growth and second, in the case of the stratospheric temperatures remaining below this threshold, but not falling below the ice frost point. It can be generally concluded from the present study that differences in PSC microphysical schemes can cause significant fluctuations in ozone depletion modelled for the winter Arctic stratosphere.Key words. Atmospheric composition and structure (aerosols and particles; cloud physics and chemistry; middle atmosphere composition and chemistry)


The use of numerical models in understanding the budgets of atmospheric trace gases is discussed. The budget of methane is calculated in a two-dimensional model. The contrasting behaviour of the Northern and Southern Hemisphere reflects changes in the relative importance of emissions, transport and chemistry. Models can also be used to test hypotheses. An example of such a study is presented in which it is shown that changes in stratospheric ozone could have played a significant role in the dramatic change in methane trend observed in the early 1990s. Finally, use of a three-dimensional model to study tropospheric trace gases is introduced.


2018 ◽  
Vol 179 ◽  
pp. 250-259 ◽  
Author(s):  
Mads P. Sulbaek Andersen ◽  
Johan A. Schmidt ◽  
Aleksandra Volkova ◽  
Donald J. Wuebbles

2010 ◽  
Vol 10 (20) ◽  
pp. 10129-10144 ◽  
Author(s):  
D. Youn ◽  
K. O. Patten ◽  
D. J. Wuebbles ◽  
H. Lee ◽  
C.-W. So

Abstract. The concept of Ozone Depletion Potentials (ODPs) is extensively used in policy considerations related to concerns about the effects of various halocarbons and other gases on stratospheric ozone. Many of the recent candidate replacement compounds have atmospheric lifetimes shorter than one year in order to limit their environmental effects, especially on stratospheric ozone. Using a three-dimensional global chemistry-transport model (CTM) of the troposphere and the stratosphere, the purpose of this study is to evaluate the potential effects of several very short-lived iodinated substances, namely iodotrifluoromethane (CF3I) and methyl iodide (CH3I), on atmospheric ozone. Like other chemicals with extremely short lifetimes, the stratospheric halogen loading and resulting ozone effects from these compounds are strongly dependent on the location of emissions. For CF3I, a possible replacement candidate for bromotrifluoromethane (CF3Br), ODPs derived by the three-dimensional model are 0.008 with chemical lifetime of 5.03 days and 0.016 with a lifetime of 1.13 days for emissions assumed to be evenly distributed over land surfaces at mid-latitudes and the tropics, respectively. While this is the first time the ODPs have been evaluated with a three-dimensional model, these values are in good agreement with those derived previously. The model calculations suggest that tropical convection could deliver a larger portion of the gas and their breakdown products to the upper troposphere and lower stratosphere if emission source is located in the tropics. The resulting ODP for CH3I, emitted from mid-latitudes, is 0.017 with lifetime of 13.59 days. Valid simulations of convective transport, vertical mixing and degradation chemistry of CH3I are shown that have good qualitative agreement between the model derived distribution of background CH3I, based on global source emission fluxes from previous studies, and available observations especially in vertical profiles.


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