Journal articles: 'CFC-11'

1

McDaniel, Anthony H., Chris A. Cantrell, James A. Davidson, Richard E. Shetter, and Jack G. Calvert. "The temperature dependent, infrared absorption cross-sections for the chlorofluorocarbons: CFC-11, CFC-12, CFC-13, CFC-14, CFC-22, CFC-113, CFC-114, and CFC-115." Journal of Atmospheric Chemistry 12, no. 3 (April 1991): 211–27. http://dx.doi.org/10.1007/bf00048074.

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2

Benjamin Plackett, special to C&EN. "CFC-11 emissions fall again." C&EN Global Enterprise 99, no. 6 (February 22, 2021): 9. http://dx.doi.org/10.1021/cen-09906-scicon6.

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3

Thomas, Max, Johannes C. Laube, Jan Kaiser, Samuel Allin, Patricia Martinerie, Robert Mulvaney, Anna Ridley, Thomas Röckmann, William T. Sturges, and Emmanuel Witrant. "Stratospheric carbon isotope fractionation and tropospheric histories of CFC-11, CFC-12, and CFC-113 isotopologues." Atmospheric Chemistry and Physics 21, no. 9 (May 5, 2021): 6857–73. http://dx.doi.org/10.5194/acp-21-6857-2021.

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Abstract. We present novel measurements of the carbon isotope composition of CFC-11 (CCl3F), CFC-12 (CCl2F2), and CFC-113 (CF2ClCFCl2), three atmospheric trace gases that are important for both stratospheric ozone depletion and global warming. These measurements were carried out on air samples collected in the stratosphere – the main sink region for these gases – and on air extracted from deep polar firn snow. We quantify, for the first time, the apparent isotopic fractionation, ϵapp(13C), for these gases as they are destroyed in the high- and mid-latitude stratosphere: ϵapp(CFC-12, high-latitude) =(-20.2±4.4) ‰, and ϵapp(CFC-113, high-latitude) =(-9.4±4.4) ‰, ϵapp(CFC-12, mid-latitude) =(-30.3±10.7) ‰, and ϵapp(CFC-113, mid-latitude) =(-34.4±9.8) ‰. Our CFC-11 measurements were not sufficient to calculate ϵapp(CFC-11), so we instead used previously reported photolytic fractionation for CFC-11 and CFC-12 to scale our ϵapp(CFC-12), resulting in ϵapp(CFC-11, high-latitude) =(-7.8±1.7) ‰ and ϵapp(CFC-11, mid-latitude) =(-11.7±4.2) ‰. Measurements of firn air were used to construct histories of the tropospheric isotopic composition, δT(13C), for CFC-11 (1950s to 2009), CFC-12 (1950s to 2009), and CFC-113 (1970s to 2009), with δT(13C) increasing for each gas. We used ϵapp(high-latitude), which was derived from more data, and a constant isotopic composition of emissions, δE(13C), to model δT(13C, CFC-11), δT(13C, CFC-12), and δT(13C, CFC-113). For CFC-11 and CFC-12, modelled δT(13C) was consistent with measured δT(13C) for the entire period covered by the measurements, suggesting that no dramatic change in δE(13C, CFC-11) or δE(13C, CFC-12) has occurred since the 1950s. For CFC-113, our modelled δT(13C, CFC-113) did not agree with our measurements earlier than 1980. This discrepancy may be indicative of a change in δE(13C, CFC-113). However, this conclusion is based largely on a single sample and only just significant outside the 95 % confidence interval. Therefore more work is needed to independently verify this temporal trend in the global tropospheric 13C isotopic composition of CFC-113. Our modelling predicts increasing δT(13C, CFC-11), δT(13C, CFC-12), and δT(13C, CFC-113) into the future. We investigated the effect of recently reported new CFC-11 emissions on background δT(13C, CFC-11) by fixing model emissions after 2012 and comparing δT(13C, CFC-11) in this scenario to the model base case. The difference in δT(13C, CFC-11) between these scenarios was 1.4 ‰ in 2050. This difference is smaller than our model uncertainty envelope and would therefore require improved modelling and measurement precision as well as better quantified isotopic source compositions to detect.

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4

Katherine Bourzac. "Oceans will become CFC-11 source." C&EN Global Enterprise 99, no. 10 (March 22, 2021): 9. http://dx.doi.org/10.1021/cen-09910-scicon5.

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5

Wang, Peidong, Jeffery R. Scott, Susan Solomon, John Marshall, Andrew R. Babbin, Megan Lickley, David W. J. Thompson, Timothy DeVries, Qing Liang, and Ronald G. Prinn. "On the effects of the ocean on atmospheric CFC-11 lifetimes and emissions." Proceedings of the National Academy of Sciences 118, no. 12 (March 15, 2021): e2021528118. http://dx.doi.org/10.1073/pnas.2021528118.

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The ocean is a reservoir for CFC-11, a major ozone-depleting chemical. Anthropogenic production of CFC-11 dramatically decreased in the 1990s under the Montreal Protocol, which stipulated a global phase out of production by 2010. However, studies raise questions about current overall emission levels and indicate unexpected increases of CFC-11 emissions of about 10 Gg ⋅ yr−1 after 2013 (based upon measured atmospheric concentrations and an assumed atmospheric lifetime). These findings heighten the need to understand processes that could affect the CFC-11 lifetime, including ocean fluxes. We evaluate how ocean uptake and release through 2300 affects CFC-11 lifetimes, emission estimates, and the long-term return of CFC-11 from the ocean reservoir. We show that ocean uptake yields a shorter total lifetime and larger inferred emission of atmospheric CFC-11 from 1930 to 2075 compared to estimates using only atmospheric processes. Ocean flux changes over time result in small but not completely negligible effects on the calculated unexpected emissions change (decreasing it by 0.4 ± 0.3 Gg ⋅ yr−1). Moreover, it is expected that the ocean will eventually become a source of CFC-11, increasing its total lifetime thereafter. Ocean outgassing should produce detectable increases in global atmospheric CFC-11 abundances by the mid-2100s, with emission of around 0.5 Gg ⋅ yr−1; this should not be confused with illicit production at that time. An illustrative model projection suggests that climate change is expected to make the ocean a weaker reservoir for CFC-11, advancing the detectable change in the global atmospheric mixing ratio by about 5 yr.

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6

Hoffmann, L., C. M. Hoppe, R. Müller, G. S. Dutton, J. C. Gille, S. Griessbach, A. Jones, et al. "Stratospheric lifetime ratio of CFC-11 and CFC-12 from satellite and model climatologies." Atmospheric Chemistry and Physics Discussions 14, no. 11 (June 25, 2014): 16865–906. http://dx.doi.org/10.5194/acpd-14-16865-2014.

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Abstract. Chlorofluorocarbons (CFCs) play a key role in stratospheric ozone loss and are strong infrared absorbers that contribute to global warming. The stratospheric lifetimes of CFCs are a measure of their global loss rates that are needed to determine global warming and ozone depletion potentials. We applied the tracer-tracer correlation approach to zonal mean climatologies from satellite measurements and model data to assess the lifetimes of CFCl3 (CFC-11) and CF2Cl2 (CFC-12). We present estimates of the CFC-11/CFC-12 lifetime ratio and the absolute lifetime of CFC-12, based on a reference lifetime of 52 yr for CFC-11. We analyzed climatologies from three satellite missions, the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS), the HIgh Resolution Dynamics Limb Sounder (HIRDLS), and the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). We found a CFC-11/CFC-12 lifetime ratio of 0.47±0.08 and a CFC-12 lifetime of 111(96–132) yr for ACE-FTS, a ratio of 0.46±0.07 and a lifetime of 112(97–133) yr for HIRDLS, and a ratio of 0.46±0.08 and a lifetime of 112(96–135) yr for MIPAS. The error-weighted, combined CFC-11/CFC-12 lifetime ratio is 0.47±0.04 and the CFC-12 lifetime estimate is 112(102–123) yr. These results agree with the recent Stratosphere-troposphere Processes And their Role in Climate (SPARC) reassessment, which recommends lifetimes of 52(43–67) yr and 102(88–122) yr, respectively. Having smaller uncertainties than the results from other recent studies, our estimates can help to better constrain CFC-11 and CFC-12 lifetime recommendations in future scientific studies and assessments. Furthermore, the satellite observations were used to validate first simulation results from a new coupled model system, which integrates a Lagrangian chemistry transport model into a climate model. For the coupled model we found a CFC-11/CFC-12 lifetime ratio of 0.48±0.07 and a CFC-12 lifetime of 110(95–129) yr, based on a ten-year perpetual run. Closely reproducing the satellite observations, the new model system will likely become a useful tool to assess the impact of advective transport, mixing, and photochemistry as well as climatological variability on the stratospheric lifetimes of long-lived tracers.

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7

Hoffmann, L., C. M. Hoppe, R. Müller, G. S. Dutton, J. C. Gille, S. Griessbach, A. Jones, et al. "Stratospheric lifetime ratio of CFC-11 and CFC-12 from satellite and model climatologies." Atmospheric Chemistry and Physics 14, no. 22 (November 27, 2014): 12479–97. http://dx.doi.org/10.5194/acp-14-12479-2014.

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Abstract. Chlorofluorocarbons (CFCs) play a key role in stratospheric ozone loss and are strong infrared absorbers that contribute to global warming. The stratospheric lifetimes of CFCs are a measure of their stratospheric loss rates that are needed to determine global warming and ozone depletion potentials. We applied the tracer–tracer correlation approach to zonal mean climatologies from satellite measurements and model data to assess the lifetimes of CFCl3 (CFC-11) and CF2Cl2 (CFC-12). We present estimates of the CFC-11/CFC-12 lifetime ratio and the absolute lifetime of CFC-12, based on a reference lifetime of 52 years for CFC-11. We analyzed climatologies from three satellite missions, the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS), the HIgh Resolution Dynamics Limb Sounder (HIRDLS), and the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). We found a CFC-11/CFC-12 lifetime ratio of 0.47±0.08 and a CFC-12 lifetime of 112(96–133) years for ACE-FTS, a ratio of 0.46±0.07 and a lifetime of 113(97–134) years for HIRDLS, and a ratio of 0.46±0.08 and a lifetime of 114(98–136) years for MIPAS. The error-weighted, combined CFC-11/CFC-12 lifetime ratio is 0.46±0.04 and the CFC-12 lifetime estimate is 113(103–124) years. These results agree with the recent Stratosphere-troposphere Processes And their Role in Climate (SPARC) reassessment, which recommends lifetimes of 52(43–67) years and 102(88–122) years, respectively. Having smaller uncertainties than the results from other recent studies, our estimates can help to better constrain CFC-11 and CFC-12 lifetime recommendations in future scientific studies and assessments. Furthermore, the satellite observations were used to validate first simulation results from a new coupled model system, which integrates a Lagrangian chemistry transport model into a climate model. For the coupled model we found a CFC-11/CFC-12 lifetime ratio of 0.48±0.07 and a CFC-12 lifetime of 110(95–129) years, based on a 10-year perpetual run. Closely reproducing the satellite observations, the new model system will likely become a useful tool to assess the impact of advective transport, mixing, and photochemistry as well as climatological variability on the stratospheric lifetimes of long-lived tracers.

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8

Hofer, Markus, and Dieter M. Imboden. "Simultaneous Determination of CFC-11, CFC-12, N2, and Ar in Water." Analytical Chemistry 70, no. 4 (February 1998): 724–29. http://dx.doi.org/10.1021/ac970499o.

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9

Christidis, N., M. D. Hurley, S. Pinnock, K. P. Shine, and T. J. Wallington. "Radiative forcing of climate change by CFC-11 and possible CFC replacements." Journal of Geophysical Research: Atmospheres 102, no. D16 (August 1, 1997): 19597–609. http://dx.doi.org/10.1029/97jd01137.

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10

Cheung, H. Michael, and Shreekumar Kurup. "Sonochemical Destruction of CFC 11 and CFC 113 in Dilute Aqueous Solution." Environmental Science & Technology 28, no. 9 (September 1994): 1619–22. http://dx.doi.org/10.1021/es00058a014.

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11

Horneman, A., M. Stute, P. Schlosser, W. Smethie, N. Santella, D. T. Ho, B. Mailloux, E. Gorman, Y. Zheng, and A. van Geen. "Degradation rates of CFC-11, CFC-12 and CFC-113 in anoxic shallow aquifers of Araihazar, Bangladesh." Journal of Contaminant Hydrology 97, no. 1-2 (April 2008): 27–41. http://dx.doi.org/10.1016/j.jconhyd.2007.12.001.

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12

Zhou, Minqiang, Corinne Vigouroux, Bavo Langerock, Pucai Wang, Geoff Dutton, Christian Hermans, Nicolas Kumps, Jean-Marc Metzger, Geoff Toon, and Martine De Mazière. "CFC-11, CFC-12 and HCFC-22 ground-based remote sensing FTIR measurements at Réunion Island and comparisons with MIPAS/ENVISAT data." Atmospheric Measurement Techniques 9, no. 11 (November 25, 2016): 5621–36. http://dx.doi.org/10.5194/amt-9-5621-2016.

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Abstract. Profiles of CFC-11 (CCl3F), CFC-12 (CCl2F2) and HCFC-22 (CHF2Cl) have been obtained from Fourier transform infrared (FTIR) solar absorption measurements above the Saint-Denis (St Denis) and Maïdo sites at Réunion Island (21° S, 55° E) with low vertical resolution. FTIR profile retrievals are performed by the well-established SFIT4 program and the detail retrieval strategies along with the systematic/random uncertainties of CFC-11, CFC-12 and HCFC-22 are discussed in this study. The FTIR data of all three species are sensitive to the whole troposphere and the lowermost stratosphere, with the peak sensitivity between 5 and 10 km. The ground-based FTIR data have been compared with the collocated Michelson Interferometer for Passive Atmospheric Sounding (MIPAS/ENVISAT) data and found to be in good agreement: the observed mean relative biases and standard deviations of the differences between the smoothed MIPAS and FTIR partial columns (6–30 km) are (−4.3 and 4.4 %), (−2.9 and 4.6 %) and (−0.7 and 4.8 %) for CFC-11, CFC-12 and HCFC-22, respectively, which are within the combined error budgets from both measurements. The season cycles of CFC-11, CFC-12 and HCFC-22 from FTIR measurements and MIPAS data show a similar variation: concentration is highest in February–April and lowest in August–October. The trends derived from the combined St Denis and Maïdo FTIR time series are −0.86 ± 0.12 and 2.84 ± 0.06 % year−1 for CFC-11 and HCFC-22, respectively, for the period 2004 to 2016, and −0.76 ± 0.05 % year−1 for CFC-12 for 2009 to 2016. These measurements are consistent with the trends observed by the National Oceanic and Atmospheric Administration (NOAA) Global Monitoring Division's (GMD) Halocarbons & other Atmospheric Trace Species Group (HATS) measurements at Samoa (14.2° S, 170.5° W) for CFC-11 (−0.87 ± 0.04 % year−1), but slightly weaker for HCFC-22 (3.46 ± 0.05 %) year−1 and stronger for CFC-12 (−0.60 ± 0.02 % year−1).

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13

Lovley, Derek R., and Joan C. Woodward. "Consumption of Freons CFC-11 and CFC-12 by anaerobic sediments and soils." Environmental Science & Technology 26, no. 5 (May 1992): 925–29. http://dx.doi.org/10.1021/es00029a009.

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14

Beining, Peter, and Wolfgang Roether. "Temporal evolution of CFC 11 and CFC 12 concentrations in the ocean interior." Journal of Geophysical Research: Oceans 101, no. C7 (July 15, 1996): 16455–64. http://dx.doi.org/10.1029/96jc00987.

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15

Kratz, David P., and Prasad Varanasi. "A reexamination of the greenhouse effect due to CFC-11 and CFC-12." Journal of Quantitative Spectroscopy and Radiative Transfer 48, no. 3 (September 1992): 245–54. http://dx.doi.org/10.1016/0022-4073(92)90014-u.

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16

Krone, Ute E., and Rudolf K. Thauer. "Dehalogenation of trichlorofluoromethane (CFC-11) byMethanosarcina barkeri." FEMS Microbiology Letters 90, no. 2 (January 1992): 201–4. http://dx.doi.org/10.1111/j.1574-6968.1992.tb05152.x.

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17

Allin, S. J., J. C. Laube, E. Witrant, J. Kaiser, E. McKenna, P. Dennis, R. Mulvaney, et al. "Chlorine isotope composition in chlorofluorocarbons CFC-11, CFC-12 and CFC-113 in firn, stratospheric and tropospheric air." Atmospheric Chemistry and Physics Discussions 14, no. 23 (December 17, 2014): 31813–41. http://dx.doi.org/10.5194/acpd-14-31813-2014.

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Abstract. The stratospheric degradation of chlorofluorocarbons (CFCs) releases chlorine, which is a major contributor to the destruction of stratospheric ozone (O3). A recent study reported strong chlorine isotope fractionation during the breakdown of the most abundant CFC (CFC-12, CCl2F2), similar to effects seen in nitrous oxide (N2O). Using air archives to obtain a long-term record of chlorine isotope ratios in CFCs could help to identify and quantify their sources and sinks. We analyse the three most abundant CFCs and show that CFC-11 (CCl3F) and CFC-113 (CClF2CCl2F) exhibit significant stratospheric chlorine isotope fractionation, in common with CFC-12. The apparent isotope fractionation (&varepsilon;app) for mid- and high-latitude stratospheric samples are (−2.4 ± 0.5) and (−2.3 ± 0.4)‰ for CFC-11, (−12.2 ± 1.6) and (−6.8 ± 0.8)‰ for CFC-12 and (−3.5 ± 1.5) and (−3.3 ± 1.2)‰ for CFC-113, respectively. Assuming a constant source isotope composition, we estimate the expected trends in the tropospheric isotope signature of these gases due to their stratospheric 37Cl enrichment and stratosphere–troposphere exchange. We compare these model results to the long-term δ(37Cl) trends of all three CFCs, measured on background tropospheric samples from the Cape Grim air archive (Tasmania, 1978–2010) and tropospheric firn air samples from Greenland (NEEM site) and Antarctica (Fletcher Promontory site). Model trends agree with tropospheric measurements within analytical uncertainties. From 1970 to the present-day, we find no evidence for variations in chlorine isotope ratios associated with changes in CFC manufacturing processes. Our study increases the suite of trace gases amenable to direct isotope ratio measurements in small air volumes, using a single-detector gas chromatography-mass spectrometry system.

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18

Allin, S. J., J. C. Laube, E. Witrant, J. Kaiser, E. McKenna, P. Dennis, R. Mulvaney, et al. "Chlorine isotope composition in chlorofluorocarbons CFC-11, CFC-12 and CFC-113 in firn, stratospheric and tropospheric air." Atmospheric Chemistry and Physics 15, no. 12 (June 23, 2015): 6867–77. http://dx.doi.org/10.5194/acp-15-6867-2015.

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Abstract. The stratospheric degradation of chlorofluorocarbons (CFCs) releases chlorine, which is a major contributor to the destruction of stratospheric ozone (O3). A recent study reported strong chlorine isotope fractionation during the breakdown of the most abundant CFC (CFC-12, CCl2F2, Laube et al., 2010a), similar to effects seen in nitrous oxide (N2O). Using air archives to obtain a long-term record of chlorine isotope ratios in CFCs could help to identify and quantify their sources and sinks. We analyse the three most abundant CFCs and show that CFC-11 (CCl3F) and CFC-113 (CClF2CCl2F) exhibit significant stratospheric chlorine isotope fractionation, in common with CFC-12. The apparent isotope fractionation (&varepsilon;app) for mid- and high-latitude stratospheric samples are respectively −2.4 (0.5) and −2.3 (0.4) ‰ for CFC-11, −12.2 (1.6) and −6.8 (0.8) ‰ for CFC-12 and −3.5 (1.5) and −3.3 (1.2) ‰ for CFC-113, where the number in parentheses is the numerical value of the standard uncertainty expressed in per mil. Assuming a constant isotope composition of emissions, we calculate the expected trends in the tropospheric isotope signature of these gases based on their stratospheric 37Cl enrichment and stratosphere–troposphere exchange. We compare these projections to the long-term δ (37Cl) trends of all three CFCs, measured on background tropospheric samples from the Cape Grim air archive (Tasmania, 1978–2010) and tropospheric firn air samples from Greenland (North Greenland Eemian Ice Drilling (NEEM) site) and Antarctica (Fletcher Promontory site). From 1970 to the present day, projected trends agree with tropospheric measurements, suggesting that within analytical uncertainties, a constant average emission isotope delta (δ) is a compatible scenario. The measurement uncertainty is too high to determine whether the average emission isotope δ has been affected by changes in CFC manufacturing processes or not. Our study increases the suite of trace gases amenable to direct isotope ratio measurements in small air volumes (approximately 200 mL), using a single-detector gas chromatography–mass spectrometry (GC–MS) system.

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19

Keeble, James, N. Luke Abraham, Alexander T. Archibald, Martyn P. Chipperfield, Sandip Dhomse, Paul T. Griffiths, and John A. Pyle. "Modelling the potential impacts of the recent, unexpected increase in CFC-11 emissions on total column ozone recovery." Atmospheric Chemistry and Physics 20, no. 12 (June 19, 2020): 7153–66. http://dx.doi.org/10.5194/acp-20-7153-2020.

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Abstract. The temporal evolution of the abundance of long-lived, anthropogenic chlorofluorocarbons in the atmosphere is a major factor in determining the timing of total column ozone (TCO) recovery. Recent observations have shown that the atmospheric mixing ratio of CFC-11 is not declining as rapidly as expected under full compliance with the Montreal Protocol and indicate a new source of CFC-11 emissions. In this study, the impact of a number of potential future CFC-11 emissions scenarios on the timing of the TCO return to the 1960–1980 mean (an important milestone on the road to recovery) is investigated using the Met Office's Unified Model (Hewitt et al., 2011) coupled with the United Kingdom Chemistry and Aerosol scheme (UM-UKCA). Key uncertainties related to this new CFC-11 source and their impact on the timing of the TCO return date are explored, including the duration of new CFC-11 production and emissions; the impact of any newly created CFC-11 bank; and the effects of co-production of CFC-12. Scenario-independent relationships are identified between cumulative CFC emissions and the timing of the TCO return date, which can be used to establish the impact of future CFC emissions pathways on ozone recovery in the real world. It is found that, for every 200 Gg Cl (∼258 Gg CFC-11) emitted, the timing of the global TCO return to 1960–1980 averaged values is delayed by ∼0.56 years. However, a marked hemispheric asymmetry in the latitudinal impacts of cumulative Cl emissions on the timing of the TCO return date is identified, with longer delays in the Southern Hemisphere than the Northern Hemisphere for the same emission. Together, these results indicate that, if rapid action is taken to curb recently identified CFC-11 production, then no significant delay in the timing of the TCO return to the 1960–1980 mean is expected, highlighting the importance of ongoing, long-term measurement efforts to inform the accountability phase of the Montreal Protocol. However, if the emissions are allowed to continue into the future and are associated with the creation of large banks, then significant delays in the timing of the TCO return date may occur.

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20

Zuiderweg, A., J. Kaiser, J. C. Laube, T. Röckmann, and R. Holzinger. "Stable carbon isotope fractionation in the UV photolysis of CFC-11 and CFC-12." Atmospheric Chemistry and Physics Discussions 11, no. 12 (December 16, 2011): 33173–89. http://dx.doi.org/10.5194/acpd-11-33173-2011.

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Abstract. The chlorofluorocarbons CFC-11 (CCl3F) and CFC-12 (CCl2F2) are stable atmospheric compounds that are produced at the earth's surface, but removed only at high altitudes in the stratosphere, where their removal liberates atomic chlorine that then catalytically destroys stratospheric ozone. For such long-lived compounds, isotope effects in the stratospheric removal reactions have a large effect on their global isotope budgets. We have determined the photolytic isotope fractionation for stable carbon isotopes of CFC-11 and CFC-12 in laboratory experiments. 13C/12C isotope fractionations (&varepsilon;) range from (−23.7 ± 0.9) to (−17.5 ± 0.4)‰ for CFC-11 and (−69.2 ± 3.4) to (−49.4 ± 2.3)‰ for CFC-12 between 203 and 288 K, a temperature range relevant to conditions in the troposphere and stratosphere. These results suggest that CFCs should become strongly enriched in 13C with decreasing mixing ratio in the stratosphere, similar to what has been recently observed for CFC chlorine isotopes. In conjunction with the strong variations in CFC emissions before and after the Montréal Protocol, the stratospheric enrichments should also lead to a significant temporal increase in the 13C content of the CFCs at the surface over the past decades, which should be recorded in atmospheric air archives such as firn air.

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21

Zuiderweg, A., J. Kaiser, J. C. Laube, T. Röckmann, and R. Holzinger. "Stable carbon isotope fractionation in the UV photolysis of CFC-11 and CFC-12." Atmospheric Chemistry and Physics 12, no. 10 (May 16, 2012): 4379–85. http://dx.doi.org/10.5194/acp-12-4379-2012.

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Abstract. The chlorofluorocarbons CFC-11 (CFCl3) and CFC-12 (CF2Cl2) are stable atmospheric compounds that are produced at the earth's surface, but removed only at high altitudes in the stratosphere by photolytic reactions. Their removal liberates atomic chlorine that then catalytically destroys stratospheric ozone. For such long-lived compounds, isotope effects in the stratospheric removal reactions have a large effect on their global isotope budgets. We have demonstrated a photolytic isotope fractionation for stable carbon isotopes of CFC-11 and CFC-12 in laboratory experiments using broadband UV-C (190–230 nm) light. 13C/12C isotope fractionations (ε) range from (−23.8±0.9) to (−17.7±0.4) ‰ for CFC-11 and (−66.2±3.1) to (−51.0±2.9) ‰ for CFC-12 between 203 and 288 K, a temperature range relevant to conditions in the troposphere and stratosphere. These results suggest that CFCs should become strongly enriched in 13C with decreasing mixing ratio in the stratosphere, similar to what has been recently observed for CFC chlorine isotopes. In conjunction with the strong variations in CFC emissions before and after the Montréal Protocol, the stratospheric enrichments should also lead to a significant temporal increase in the 13C content of the CFCs at the surface over the past decades, which should be recorded in atmospheric air archives such as firn air.

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22

Mangani, Filippo, Michela Maione, and Luciano Lattanzi. "Significance of selected halocarbons monitoring in air samples collected in the Terra Nova Bay region (northern Victoria Land, Antarctica)." Antarctic Science 11, no. 2 (June 1999): 261–64. http://dx.doi.org/10.1017/s0954102099000322.

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CCl3F (or CFC-11) and CCl2F2 (or CFC-12) were determined in air samples collected, during subsequent summer Antarctic campaigns, in different sampling sites in the Ross Sea Region. The samples were analysed by GC-ECD after enrichment. Data obtained since 1988–89 were plotted to observe the trend of CFCs atmospheric concentration levels. A decrease in the rate of increase of CFC-12 concentration was observed, whilst the concentration of CFC-11 was actually seen to be decreasing.

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23

Zhen, Jiebo, Minmin Yang, Jie Zhou, Fengchun Yang, Tao Li, Hongli Li, Fangfang Cao, Xiaoling Nie, Panyan Li, and Yan Wang. "Monitoring Chlorofluorocarbons in Potential Source Regions in Eastern China." Atmosphere 11, no. 12 (November 30, 2020): 1299. http://dx.doi.org/10.3390/atmos11121299.

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Recent studies have indicated that Eastern China might be a potential source region of increased atmospheric chlorofluorocarbons (CFCs). To investigate this possibility, a field measurement was carried out from October to December 2017 for identifying the ambient concentration levels of representative trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), trifluorotrichloroethane (CFC-113), and tetrafluorodichloroethane (CFC-114) at the residential and municipal solid waste (MSW) landfills and industrial sites in Eastern China. The ambient mixing ratios of CFCs at residential sites were almost within 20% enhancements of the global background sites. The highest levels of CFCs were observed at the MSW landfill sites. Moreover, CFC-11 and CFC-113 concentrations at MSW landfill, which was in service, were two times higher than that at completed MSW landfill. Mean concentrations of 322 pptv for CFC-11, 791 pptv for CFC-12, 91 pptv for CFC-113, and 16 pptv for CFC-114 at various industrial sites were higher than those at residential sites, but they were obviously lower than that at MSW landfill in use. A poor intercorrelation between the CFCs indicated that they did not come from the same source. Higher concentrations measured in this study compared with background sites indicates that MSW landfills could be an unintentional emission source and there are still substantial amounts of CFCs being stored in banks that may discharge CFCs into the atmosphere in Eastern China.

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Hoffmann, L., M. Kaufmann, R. Spang, R. Müller, J. J. Remedios, D. P. Moore, C. M. Volk, T. von Clarmann, and M. Riese. "Envisat MIPAS measurements of CFC-11: retrieval, validation, and climatology." Atmospheric Chemistry and Physics Discussions 8, no. 2 (March 4, 2008): 4561–602. http://dx.doi.org/10.5194/acpd-8-4561-2008.

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Abstract. From July 2002 to March 2004 the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) aboard the European Space Agency's Environmental Satellite (Envisat) measured nearly continuously mid infrared limb radiance spectra. These measurements are utilised to retrieve the global distribution of the chlorofluorocarbon CFC-11 by applying a new fast forward model for Envisat MIPAS and an accompanying optimal estimation retrieval processor. A detailed analysis shows that the total retrieval errors of the individual CFC-11 volume mixing ratios are typically below 10% and that the systematic components are dominating. Contribution of a priori information to the retrieval results are less than 5 to 10%. The vertical resolution of the observations is about 3 to 4 km. The data are successfully validated by comparison with several other space experiments, an air-borne in-situ instrument, measurements from ground-based networks, and independent Envisat MIPAS analyses. The retrieval results from 425 000 Envisat MIPAS limb scans are compiled to provide a new climatological data set of CFC-11. The climatology shows significantly lower CFC-11 abundances in the lower stratosphere compared with the Reference Atmospheres for MIPAS (RAMstan V3.1) climatology. Depending on the atmospheric conditions the differences between the climatologies are up to 30 to 110 ppt (45 to 150%) at 19 to 27 km altitude. Additionally, time series of CFC-11 mean abundance and variability for five latitudinal bands are presented. The observed CFC-11 distributions can be explained by the residual mean circulation and large-scale eddy-transports in the upper troposphere and lower stratosphere. The new CFC-11 data set is well suited for further scientific studies.

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Eckert, E., A. Laeng, S. Lossow, S. Kellmann, G. Stiller, T. von Clarmann, N. Glatthor, et al. "MIPAS IMK/IAA CFC-11 (CCl3F) and CFC-12 (CCl2F2) measurements: accuracy, precision and long-term stability." Atmospheric Measurement Techniques 9, no. 7 (July 28, 2016): 3355–89. http://dx.doi.org/10.5194/amt-9-3355-2016.

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Abstract. Profiles of CFC-11 (CCl3F) and CFC-12 (CCl2F2) of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) aboard the European satellite Envisat have been retrieved from versions MIPAS/4.61 to MIPAS/4.62 and MIPAS/5.02 to MIPAS/5.06 level-1b data using the scientific level-2 processor run by Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research (IMK) and Consejo Superior de Investigaciones Científicas (CSIC), Instituto de Astrofísica de Andalucía (IAA). These profiles have been compared to measurements taken by the balloon-borne cryosampler, Mark IV (MkIV) and MIPAS-Balloon (MIPAS-B), the airborne MIPAS-STRatospheric aircraft (MIPAS-STR), the satellite-borne Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) and the High Resolution Dynamic Limb Sounder (HIRDLS), as well as the ground-based Halocarbon and other Atmospheric Trace Species (HATS) network for the reduced spectral resolution period (RR: January 2005–April 2012) of MIPAS. ACE-FTS, MkIV and HATS also provide measurements during the high spectral resolution period (full resolution, FR: July 2002–March 2004) and were used to validate MIPAS CFC-11 and CFC-12 products during that time, as well as profiles from the Improved Limb Atmospheric Spectrometer, ILAS-II. In general, we find that MIPAS shows slightly higher values for CFC-11 at the lower end of the profiles (below ∼ 15 km) and in a comparison of HATS ground-based data and MIPAS measurements at 3 km below the tropopause. Differences range from approximately 10 to 50 pptv ( ∼ 5–20 %) during the RR period. In general, differences are slightly smaller for the FR period. An indication of a slight high bias at the lower end of the profile exists for CFC-12 as well, but this bias is far less pronounced than for CFC-11 and is not as obvious in the relative differences between MIPAS and any of the comparison instruments. Differences at the lower end of the profile (below ∼ 15 km) and in the comparison of HATS and MIPAS measurements taken at 3 km below the tropopause mainly stay within 10–50 pptv (corresponding to ∼ 2–10 % for CFC-12) for the RR and the FR period. Between ∼ 15 and 30 km, most comparisons agree within 10–20 pptv (10–20 %), apart from ILAS-II, which shows large differences above ∼ 17 km. Overall, relative differences are usually smaller for CFC-12 than for CFC-11. For both species – CFC-11 and CFC-12 – we find that differences at the lower end of the profile tend to be larger at higher latitudes than in tropical and subtropical regions. In addition, MIPAS profiles have a maximum in their mixing ratio around the tropopause, which is most obvious in tropical mean profiles. Comparisons of the standard deviation in a quiescent atmosphere (polar summer) show that only the CFC-12 FR error budget can fully explain the observed variability, while for the other products (CFC-11 FR and RR and CFC-12 RR) only two-thirds to three-quarters can be explained. Investigations regarding the temporal stability show very small negative drifts in MIPAS CFC-11 measurements. These instrument drifts vary between ∼ 1 and 3 % decade−1. For CFC-12, the drifts are also negative and close to zero up to ∼ 30 km. Above that altitude, larger drifts of up to ∼ 50 % decade−1 appear which are negative up to ∼ 35 km and positive, but of a similar magnitude, above.

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26

Marani, Luciano, Plínio Carlos Alvalá, and Volker Walter Johann Heinrich Kirchhoff. "Residual emissions of CFC-11 and CFC-12 in the São Paulo metropolitan area." Revista Brasileira de Geofísica 24, no. 4 (December 2006): 459–66. http://dx.doi.org/10.1590/s0102-261x2006000400001.

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27

Hoffmann, L., M. Kaufmann, R. Spang, R. Müller, J. J. Remedios, D. P. Moore, C. M. Volk, T. von Clarmann, and M. Riese. "Envisat MIPAS measurements of CFC-11: retrieval, validation, and climatology." Atmospheric Chemistry and Physics 8, no. 13 (July 10, 2008): 3671–88. http://dx.doi.org/10.5194/acp-8-3671-2008.

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Abstract. From July 2002 to March 2004 the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) aboard the European Space Agency's Environmental Satellite (Envisat) measured nearly continuously mid infrared limb radiance spectra. These measurements are utilised to retrieve the global distribution of the chlorofluorocarbon CFC-11 by applying a new fast forward model for Envisat MIPAS and an accompanying optimal estimation retrieval processor. A detailed analysis shows that the total retrieval errors of the individual CFC-11 volume mixing ratios are typically below 10% in the altitude range 10 to 25 km and that the systematic components dominate. Contribution of a priori information to the retrieval results are less than 5 to 10% and the vertical resolution of the observations is about 3 to 4 km in the same vertical range. The data are successfully validated by comparison with several other space experiments, an air-borne in-situ instrument, measurements from ground-based networks, and independent Envisat MIPAS analyses. The retrieval results from 425 000 Envisat MIPAS limb scans are compiled to provide a new climatological data set of CFC-11. The climatology shows significantly lower CFC-11 abundances in the lower stratosphere compared with the Reference Atmospheres for MIPAS (RAMstan V3.1) climatology. Depending on the atmospheric conditions the differences between the climatologies are up to 30 to 110 ppt (45 to 150%) at 19 to 27 km altitude. Additionally, time series of CFC-11 mean abundance and variability for five latitudinal bands are presented. The observed CFC-11 distributions can be explained by the residual mean circulation and large-scale eddy-transports in the upper troposphere and lower stratosphere. The new CFC-11 data set is well suited for further scientific studies.

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28

Minschwaner, K., L. Hoffmann, A. Brown, M. Riese, R. Müller, and P. F. Bernath. "Stratospheric loss and atmospheric lifetimes of CFC-11 and CFC-12 derived from satellite observations." Atmospheric Chemistry and Physics Discussions 12, no. 11 (November 5, 2012): 28733–64. http://dx.doi.org/10.5194/acpd-12-28733-2012.

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Abstract. The lifetimes of CFC-11 and CFC-12 have been evaluated using global observations of their stratospheric distributions from satellite-based instruments between the period 1992 and 2010. The CFC data sets are from the Cryogen Limb Array Etalon Spectrometer (CLAES), the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA-1 and CRISTA-2), the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), and the Atmospheric Chemistry Experiment (ACE). Stratospheric loss rates were calculated using an ultraviolet radiative transfer code with updated cross section and solar irradiance data. Mean steady state lifetimes based on these observations are 50.3 ± 16.8 yr for CFC-11 and 106.9 ± 21.7 yr for CFC-12, which are in reasonable agreement with the most recent WMO Ozone Assessment recommendations but are somewhat longer by 12% and 7%, respectively. There are two major sources of error in calculating lifetimes using this method. One error source is due to uncertainties in tropical stratospheric measurements, particularly for CFC-11. Another large contribution to the error arises from uncertainties in the penetration of solar ultraviolet radiation at wavelengths between 185 and 220 nm, primarily in the tropical stratosphere between 20 and 35 km altitude.

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29

Minschwaner, K., L. Hoffmann, A. Brown, M. Riese, R. Müller, and P. F. Bernath. "Stratospheric loss and atmospheric lifetimes of CFC-11 and CFC-12 derived from satellite observations." Atmospheric Chemistry and Physics 13, no. 8 (April 24, 2013): 4253–63. http://dx.doi.org/10.5194/acp-13-4253-2013.

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Abstract. The lifetimes of CFC-11 and CFC-12 have been evaluated using global observations of their stratospheric distributions from satellite-based instruments over the time period from 1992 to 2010. The chlorofluorocarbon (CFC) datasets are from the Cryogen Limb Array Etalon Spectrometer (CLAES), the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA-1 and CRISTA-2), the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), and the Atmospheric Chemistry Experiment (ACE). Stratospheric loss rates were calculated using an ultraviolet radiative transfer code with updated cross section and solar irradiance data. Mean steady-state lifetimes based on these observations are 44.7 (36–58) yr for CFC-11 and 106.6 (90–130) yr for CFC-12, which are in good agreement with the most recent WMO ozone assessment. There are two major sources of error in calculating lifetimes using this method. The first important error arises from uncertainties in tropical stratospheric observations, particularly for CFC-11. Another large contribution to the error is due to uncertainties in the penetration of solar ultraviolet radiation at wavelengths between 185 and 220 nm, primarily in the tropical stratosphere between 20 and 35 km altitude.

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30

Zhang, Fang, Lingxi Zhou, Bo Yao, Martin K. Vollmer, Brian R. Greally, Peter G. Simmonds, Stefan Reimann, Frode Stordal, Michela Maione, and Lin Xu. "Analysis of 3-year observations of CFC-11, CFC-12 and CFC-113 from a semi-rural site in China." Atmospheric Environment 44, no. 35 (November 2010): 4454–62. http://dx.doi.org/10.1016/j.atmosenv.2010.07.041.

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31

Qin, Dajun. "Decline in the concentrations of chlorofluorocarbons (CFC-11, CFC-12 and CFC-113) in an urban area of Beijing, China." Atmospheric Environment 41, no. 38 (December 2007): 8424–30. http://dx.doi.org/10.1016/j.atmosenv.2007.07.005.

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32

Hong, Seong-Uk, and J. Larry Duda. "Diffusion of CFC 11 and hydrofluorocarbons in polyurethane." Journal of Applied Polymer Science 70, no. 10 (December 5, 1998): 2069–73. http://dx.doi.org/10.1002/(sici)1097-4628(19981205)70:10<2069::aid-app23>3.0.co;2-4.

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33

KOBAYASHI-KIRSCHVINK, KOSEKI J., KING-FAI LI, RUN-LIE SHIA, and YUK L. YUNG. "FUNDAMENTAL MODES OF ATMOSPHERIC CFC-11 FROM EMPIRICAL MODE DECOMPOSITION." Advances in Adaptive Data Analysis 04, no. 04 (October 2012): 1250024. http://dx.doi.org/10.1142/s1793536912500240.

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Following an initial growth, the concentrations of chlorofluorocarbon-11 (CFC-11) in the atmosphere started to decline in the 1990's due to world-wide legislative control on emissions. The amplitude of the annual cycle of CFC-11 was much larger in the earlier period compared with that in the later period. We apply here the Ensemble Empirical Mode Decomposition (EEMD) analysis to the CFC-11 data obtained by the U.S. National Oceanic and Atmospheric Administration. The sum of the second and third intrinsic mode functions (IMFs) represents the annual cycle, which shows that the annual cycle of CFC-11 has varied by a factor of 2–3 from the mid-1970's to the present over polar regions. The results provide an illustration of the power of the EEMD method in extracting a variable annual cycle from data dominated by increasing and decreasing trends. Finally, we compare the annual cycle obtained by the EEMD analysis to that obtained using conventional methods such as Fourier transforms and running averages.

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34

Shao, Andrew E., Sabine Mecking, LuAnne Thompson, and Rolf E. Sonnerup. "Mixed layer saturations of CFC-11, CFC-12, and SF6 in a global isopycnal model." Journal of Geophysical Research: Oceans 118, no. 10 (October 2013): 4978–88. http://dx.doi.org/10.1002/jgrc.20370.

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35

Happell, James D., René M. Price, Zafer Top, and Peter K. Swart. "Evidence for the removal of CFC-11, CFC-12, and CFC-113 at the groundwater–surface water interface in the Everglades." Journal of Hydrology 279, no. 1-4 (August 2003): 94–105. http://dx.doi.org/10.1016/s0022-1694(03)00169-0.

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36

Massolo, Serena, Paola Rivaro, and Roberto Frache. "Simultaneous determination of CFC-11, CFC-12 and CFC-113 in seawater samples using a purge and trap gas-chromatographic system." Talanta 80, no. 2 (December 15, 2009): 959–66. http://dx.doi.org/10.1016/j.talanta.2009.08.021.

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37

Walker, S. J., R. F. Weiss, and P. K. Salameh. "Reconstructed histories of the annual mean atmospheric mole fractions for the halocarbons CFC-11 CFC-12, CFC-113, and carbon tetrachloride." Journal of Geophysical Research: Oceans 105, no. C6 (June 15, 2000): 14285–96. http://dx.doi.org/10.1029/1999jc900273.

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38

Chambers, L. A., D. C. Gooddy, and A. M. Binley. "Use and application of CFC-11, CFC-12, CFC-113 and SF6 as environmental tracers of groundwater residence time: A review." Geoscience Frontiers 10, no. 5 (September 2019): 1643–52. http://dx.doi.org/10.1016/j.gsf.2018.02.017.

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39

Rigby, M., R. G. Prinn, S. O'Doherty, S. A. Montzka, A. McCulloch, C. M. Harth, J. Mühle, et al. "Re-evaluation of the lifetimes of the major CFCs and CH3CCl3 using atmospheric trends." Atmospheric Chemistry and Physics Discussions 12, no. 9 (September 18, 2012): 24469–99. http://dx.doi.org/10.5194/acpd-12-24469-2012.

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Abstract. Since the Montreal Protocol on substances that deplete the ozone layer and its amendments came into effect, growth rates of the major ozone depleting substances (ODS), particularly CFC-11, -12 and -113 and CH3CCl3, have declined markedly, paving the way for global stratospheric ozone recovery. Emissions have now fallen to relatively low levels, therefore the rate at which this recovery occurs will depend largely on the atmospheric lifetime of these compounds. The first ODS measurements began in the early 1970s along with the first lifetime estimates calculated by considering their atmospheric trends. We now have global mole fraction records spanning multiple decades, prompting this lifetime re-evaluation. Using surface measurements from the Advanced Global Atmospheric Gases Experiment (AGAGE) and the National Oceanic and Atmospheric Administration Global Monitoring Division (NOAA GMD) from 1978 to 2011, we estimated the lifetime of CFC-11, CFC-12, CFC-113 and CH3CCl3 using a multi-species inverse method. The CFC-11 lifetime of 45 yr, currently recommended in the World Meteorological Organisation (WMO) Scientific Assessment of Ozone Depletion, lies at the lower uncertainty bound of our estimates which are 524066 yr (1-sigma uncertainty) when AGAGE data were used, and 504066 yr when the NOAA network data were used. Our derived lifetime for CFC-113 is higher than the WMO estimates of 85 yr (10488123 using AGAGE, 10387122 using NOAA). Our estimates of the lifetime of CFC-12 and CH3CCl3 agree well with other recent estimates being 10885137 and 10484135 yr (CFC-12, AGAGE and NOAA, respectively) and 5.24.85.6 and 5.24.85.7 yr (CH3CCl3, AGAGE and NOAA, respectively).

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40

Altan, H., B. L. Yu, S. A. Alfano, and R. R. Alfano. "Terahertz (THz) spectroscopy of Freon-11 (CCl3F, CFC-11) at room temperature." Chemical Physics Letters 427, no. 4-6 (August 2006): 241–45. http://dx.doi.org/10.1016/j.cplett.2006.06.064.

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41

Dameris, Martin, Patrick Jöckel, and Matthias Nützel. "Possible implications of enhanced chlorofluorocarbon-11 concentrations on ozone." Atmospheric Chemistry and Physics 19, no. 22 (November 15, 2019): 13759–71. http://dx.doi.org/10.5194/acp-19-13759-2019.

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Abstract. This numerical model study is motivated by the observed global deviation from assumed emissions of chlorofluorocarbon-11 (CFC-11, CFCl3) in recent years. Montzka et al. (2018) discussed a strong deviation of the assumed emissions of CFC-11 over the past 15 years, which indicates a violation of the Montreal Protocol for the protection of the ozone layer. An investigation is performed which is based on chemistry–climate model (CCM) simulations that analyze the consequences of an enhanced CFC-11 surface mixing ratio. In comparison to a reference simulation (REF-C2), where a decrease of the CFC-11 surface mixing ratio of about 50 % is assumed from the early 2000s to the middle of the century (i.e., a mixing ratio in full compliance with the Montreal Protocol agreement), two sensitivity simulations are carried out. In the first simulation the CFC-11 surface mixing ratio is kept constant after the year 2002 until 2050 (SEN-C2-fCFC11_2050); this allows a qualitative estimate of possible consequences of a high-level stable CFC-11 surface mixing ratio on the ozone layer. In the second sensitivity simulation, which is branched off from the first sensitivity simulation, it is assumed that the Montreal Protocol is fully implemented again starting in the year 2020, which leads to a delayed decrease of CFC-11 in this simulation (SEN-C2-fCFC11_2020) compared with the reference simulation; this enables a rough and most likely upper-limit assessment of how much the unexpected CFC-11 emissions to date have already affected ozone. In all three simulations, the climate evolves under the same greenhouse gas scenario (i.e., RCP6.0) and all other ozone-depleting substances decline (according to this scenario). Differences between the reference (REF-C2) and the two sensitivity simulations (SEN-C2-fCFC11_2050 and SEN-C2-fCFC11_2020) are discussed. In the SEN-C2-fCFC11_2050 simulation, the total column ozone (TCO) in the 2040s (i.e., the years 2041–2050) is particularly affected in both polar regions in winter and spring. Maximum discrepancies in the TCO values are identified with reduced ozone values of up to around 30 Dobson units in the Southern Hemisphere (SH) polar region during SH spring (in the order of 15 %). An analysis of the respective partial column ozone (PCO) for the stratosphere indicates that the strongest ozone changes are calculated for the polar lower stratosphere, where they are mainly driven by the enhanced stratospheric chlorine content and associated heterogeneous chemical processes. Furthermore, it was found that the calculated ozone changes, especially in the upper stratosphere, are surprisingly small. For the first time in such a scenario, we perform a complete ozone budget analysis regarding the production and loss cycles. In the upper stratosphere, the budget analysis shows that the additional ozone depletion due to the catalysis by reactive chlorine is partly compensated for by other processes related to enhanced ozone production or reduced ozone loss, for instance from nitrous oxide (NOx). Based on the analysis of the SEN-C2-fCFC11_2020 simulation, it was found that no major ozone changes can be expected after the year 2050, and that these changes are related to the enhanced CFC-11 emissions in recent years.

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42

Eckert, E., A. Laeng, S. Lossow, S. Kellmann, G. Stiller, T. von Clarmann, N. Glatthor, et al. "MIPAS IMK/IAA CFC-11 (CCl3F) and CFC-12 (CCl2F2) measurements: accuracy, precision and long-term stability." Atmospheric Measurement Techniques Discussions 8, no. 7 (July 23, 2015): 7573–662. http://dx.doi.org/10.5194/amtd-8-7573-2015.

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Abstract. Profiles of CFC-11 (CCl3F) and CFC-12 (CCl2F2) of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) abord the European satellite Envisat have been retrieved from versions MIPAS/4.61–MIPAS/4.62 and MIPAS/5.02–MIPAS/5.06 level-1b data using the scientific level-2 processor run by Karlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research (IMK) and Consejo Superior de Investigaciones Científicas (CSIC), Instituto de Astrofísica de Andalucía (IAA). These profiles have been compared to measurements taken by the balloon borne Cryosampler, Mark IV (MkIV) and MIPAS-Balloon (MIPAS-B), the airborne MIPAS stratospheric aircraft (MIPAS-STR), the satellite borne Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) and the High Resolution Dynamic Limb Sounder (HIRDLS) as well as the ground based Halocarbon and other Atmospheric Trace Species (HATS) network for the reduced spectral resolution period (RR: January 2005–April 2012) of MIPAS Envisat. ACE-FTS, MkIV and HATS also provide measurements during the high spectral resolution period (FR: July 2002–March 2004) and were used to validate MIPAS Envisat CFC-11 and CFC-12 products during that time, as well as ILAS-II profiles. In general, we find that MIPAS Envisat shows slightly higher values for CFC-11 at the lower end of the profiles (below ~ 15 km) and in a comparison of HATS ground-based data and MIPAS Envisat measurements at 3 km below the tropopause. Differences range from approximately 10–50 pptv (~ 5–20 %) during the RR period. In general, differences are slightly smaller for the FR period. An indication of a slight high-bias at the lower end of the profile exists for CFC-12 as well, but this bias is far less pronounced than for CFC-11, so that differences at the lower end of the profile (below ~ 15 km) and in the comparison of HATS and MIPAS Envisat measurements taken at 3 km below the tropopause mainly stay within 10–50 pptv (~ 2–10 %) for the RR and the FR period. Above approximately 15 km, most comparisons are close to excellent, apart from ILAS-II, which shows large differences above ~ 17 km. Overall, percentage differences are usually smaller for CFC-12 than for CFC-11. For both species – CFC-11 and CFC-12 – we find that differences at the lower end of the profile tend to be larger at higher latitudes than in tropical and subtropical regions. In addition, MIPAS Envisat profiles have a maximum in the mixing ratio around the tropopause, which is most obvious in tropical mean profiles. Estimated measurement noise alone can, in most cases, not explain the standard deviation of the differences. This is attributed to error components not considered in the error estimate and also to natural variability which always plays a role when the compared instruments do not measure exactly the same air mass. Investigations concerning the temporal stability show very small negative drifts in MIPAS Envisat CFC-11 measurements. These drifts vary between ~ 1–3 % decade−1. For CFC-12, the drifts are also negative and close to zero up to ~ 30 km. Above that altitude larger drifts of up to ~ 50 % decade−1 appear which are negative up to ~ 35 km and positive, but of a similar magnitude, above.

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43

Rigby, M., R. G. Prinn, S. O'Doherty, S. A. Montzka, A. McCulloch, C. M. Harth, J. Mühle, et al. "Re-evaluation of the lifetimes of the major CFCs and CH3CCl3 using atmospheric trends." Atmospheric Chemistry and Physics 13, no. 5 (March 6, 2013): 2691–702. http://dx.doi.org/10.5194/acp-13-2691-2013.

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Abstract. Since the Montreal Protocol on Substances that Deplete the Ozone Layer and its amendments came into effect, growth rates of the major ozone depleting substances (ODS), particularly CFC-11, -12 and -113 and CH3CCl3, have declined markedly, paving the way for global stratospheric ozone recovery. Emissions have now fallen to relatively low levels, therefore the rate at which this recovery occurs will depend largely on the atmospheric lifetime of these compounds. The first ODS measurements began in the early 1970s along with the first lifetime estimates calculated by considering their atmospheric trends. We now have global mole fraction records spanning multiple decades, prompting this lifetime re-evaluation. Using surface measurements from the Advanced Global Atmospheric Gases Experiment (AGAGE) and the National Oceanic and Atmospheric Administration Global Monitoring Division (NOAA GMD) from 1978 to 2011, we estimated the lifetime of CFC-11, CFC-12, CFC-113 and CH3CCl3 using a multi-species inverse method. A steady-state lifetime of 45 yr for CFC-11, currently recommended in the most recent World Meteorological Organisation (WMO) Scientific Assessments of Ozone Depletion, lies towards the lower uncertainty bound of our estimates, which are 544861 yr (1-sigma uncertainty) when AGAGE data were used and 524561 yr when the NOAA network data were used. Our derived lifetime for CFC-113 is significantly higher than the WMO estimates of 85 yr, being 10999121 (AGAGE) and 10997124 (NOAA). New estimates of the steady-state lifetimes of CFC-12 and CH3CCl3 are consistent with the current WMO recommendations, being 11195132 and 11295136 yr (CFC-12, AGAGE and NOAA respectively) and 5.044.925.20 and 5.044.875.23 yr (CH3CCl3, AGAGE and NOAA respectively).

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44

Martinerie, P., E. Nourtier-Mazauric, J. M. Barnola, W. T. Sturges, D. R. Worton, E. Atlas, L. K. Gohar, K. P. Shine, and G. P. Brasseur. "Long-lived halocarbon trends and budgets from atmospheric chemistry modelling constrained with measurements in polar firn." Atmospheric Chemistry and Physics 9, no. 12 (June 17, 2009): 3911–34. http://dx.doi.org/10.5194/acp-9-3911-2009.

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Abstract. The budgets of seven halogenated gases (CFC-11, CFC-12, CFC-113, CFC-114, CFC-115, CCl4 and SF6) are studied by comparing measurements in polar firn air from two Arctic and three Antarctic sites, and simulation results of two numerical models: a 2-D atmospheric chemistry model and a 1-D firn diffusion model. The first one is used to calculate atmospheric concentrations from emission trends based on industrial inventories; the calculated concentration trends are used by the second one to produce depth concentration profiles in the firn. The 2-D atmospheric model is validated in the boundary layer by comparison with atmospheric station measurements, and vertically for CFC-12 by comparison with balloon and FTIR measurements. Firn air measurements provide constraints on historical atmospheric concentrations over the last century. Age distributions in the firn are discussed using a Green function approach. Finally, our results are used as input to a radiative model in order to evaluate the radiative forcing of our target gases. Multi-species and multi-site firn air studies allow to better constrain atmospheric trends. The low concentrations of all studied gases at the bottom of the firn, and their consistency with our model results confirm that their natural sources are small. Our results indicate that the emissions, sinks and trends of CFC-11, CFC-12, CFC-113, CFC-115 and SF6 are well constrained, whereas it is not the case for CFC-114 and CCl4. Significant emission-dependent changes in the lifetimes of halocarbons destroyed in the stratosphere were obtained. Those result from the time needed for their transport from the surface where they are emitted to the stratosphere where they are destroyed. Efforts should be made to update and reduce the large uncertainties on CFC lifetimes.

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45

Martinerie, P., E. Nourtier-Mazauric, J. M. Barnola, W. T. Sturges, D. R. Worton, E. Atlas, L. K. Gohar, K. P Shine, and G. P. Brasseur. "Long-lived halocarbon trends and budgets from atmospheric chemistry modelling constrained with measurements in polar firn." Atmospheric Chemistry and Physics Discussions 9, no. 1 (January 13, 2009): 991–1049. http://dx.doi.org/10.5194/acpd-9-991-2009.

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Abstract. The budgets of seven halogenated gases (CFC-11, CFC-12, CFC-113, CFC-114, CFC-115, CCl4 and SF6) are studied by comparing measurements in polar firn air from two Arctic and three Antarctic sites, and simulation results of two numerical models: a 2-D atmospheric chemistry model and a 1-D firn diffusion model. The first one is used to calculate atmospheric concentrations from emission trends based on industrial inventories; the calculated concentration trends are used by the second one to produce depth concentration profiles in the firn. The 2-D atmospheric model is validated in the boundary layer by comparison with atmospheric station measurements, and vertically for CFC-12 by comparison with balloon and FTIR measurements. Firn air measurements provide constraints on historical atmospheric concentrations over the last century. Age distributions in the firn are discussed using a Green function approach. Finally, our results are used as input to a radiative model in order to evaluate the radiative forcing of our target gases. Multi-species and multi-site firn air studies allow to better constrain atmospheric trends. The low concentrations of all studied gases at the bottom of the firn, and their consistency with our model results confirm that their natural sources are insignificant. Our results indicate that the emissions, sinks and trends of CFC-11, CFC-12, CFC-113, CFC-115 and SF6 are well constrained, whereas it is not the case for CFC-114 and CCl4. Significant emission-dependent changes in the lifetimes of halocarbons destroyed in the stratosphere were obtained. Those result from the time needed for their transport from the surface where they are emitted to the stratosphere where they are destroyed. Efforts should be made to update and reduce the large uncertainties on CFC lifetimes.

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46

Zheng, Min, Warren J. De Bruyn, and Eric S. Saltzman. "Measurements of the diffusion coefficients of CFC-11 and CFC-12 in pure water and seawater." Journal of Geophysical Research: Oceans 103, no. C1 (January 15, 1998): 1375–79. http://dx.doi.org/10.1029/97jc02761.

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47

Warner, Mark J., J. L. Bullister, D. P. Wisegarver, R. H. Gammon, and R. F. Weiss. "Basin-wide distributions of chlorofluorocarbons CFC-11 and CFC-12 in the North Pacific: 1985-1989." Journal of Geophysical Research: Oceans 101, no. C9 (September 15, 1996): 20525–42. http://dx.doi.org/10.1029/96jc01849.

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48

Montague, D. C., and R. L. Perrine. "Preliminary assessment of the greenhouse warming implications of halocarbon substitutes for CFC-11 and CFC-12." Atmospheric Environment. Part A. General Topics 24, no. 5 (January 1990): 1331–39. http://dx.doi.org/10.1016/0960-1686(90)90098-8.

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49

Kellmann, S., T. von Clarmann, G. P. Stiller, E. Eckert, N. Glatthor, M. Höpfner, M. Kiefer, et al. "Global CFC-11 (CFCl3) and CFC-12 (CF2Cl2) measurements with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS): retrieval, climatologies and trends." Atmospheric Chemistry and Physics Discussions 12, no. 7 (July 25, 2012): 18325–77. http://dx.doi.org/10.5194/acpd-12-18325-2012.

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Abstract. Vertical profiles of CFC-11 (CFCl3) and CFC-12 (CF2Cl2) have been measured with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) with global coverage under daytime and nighttime conditions. The profile retrieval is based on constrained nonlinear least squares fitting of measured limb spectral radiance to modeled spectra. CFC-11 is measured in its ν4-band at 850 cm−1, and CFC-12 is analyzed in its ν6-band at 922 cm−1. To stabilize the retrievals, a Tikhonov-type smoothing constraint is applied. Main retrieval error sources are measurement noise and elevation pointing uncertainties. The estimated CFC-11 retrieval errors including noise and parameter errors but excluding spectroscopic data uncertainties are below 10 pptv in the middle stratosphere, depending on altitude, the MIPAS measurement mode and the actual atmospheric situation. For CFC-12 the total retrieval errors are below 28 pptv at an altitude resolution varying from 3 to 5 km. Time series of altitude/latitude bins were fitted by a simple parametric approach including constant and linear terms, a quasi-biennial oscillation (QBO) proxy and sine and cosine terms of several periods. In the time series from 2002 to 2011, quasi-biennial and annual oscillations are clearly visible. A decrease of stratospheric CFC mixing ratios in response to the Montreal Protocol is observed for most altitudes and latitudes. However, the trends differ from the trends measured in the troposphere, they are even positive at some latitudes and altitudes, and can in some cases only be explained by decadal changes in atmospheric age of air spectra or vertical mixing patterns.

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50

Kellmann, S., T. von Clarmann, G. P. Stiller, E. Eckert, N. Glatthor, M. Höpfner, M. Kiefer, et al. "Global CFC-11 (CCl3F) and CFC-12 (CCl2F2) measurements with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS): retrieval, climatologies and trends." Atmospheric Chemistry and Physics 12, no. 24 (December 17, 2012): 11857–75. http://dx.doi.org/10.5194/acp-12-11857-2012.

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Abstract. Vertical profiles of CFC-11 (CCl3F) and CFC-12 (CCl2F2) have been measured with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) with global coverage under daytime and nighttime conditions. The profile retrieval is based on constrained nonlinear least squares fitting of measured limb spectral radiance to modeled spectra. CFC-11 is measured in its ν4-band at 850 cm−1, and CFC-12 is analyzed in its ν6-band at 922 cm−1. To stabilize the retrievals, a Tikhonov-type smoothing constraint is applied. Main retrieval error sources are measurement noise and elevation pointing uncertainties. The estimated CFC-11 retrieval errors including noise and parameter errors but excluding spectroscopic data uncertainties are below 10 pptv in the middle stratosphere, depending on altitude, the MIPAS measurement mode and the actual atmospheric situation. For CFC-12 the total retrieval errors are below 28 pptv at an altitude resolution varying from 3 to 5 km. Time series of altitude/latitude bins were fitted by a simple parametric approach including constant and linear terms, a quasi-biennial oscillation (QBO) proxy and sine and cosine terms of several periods. In the time series from 2002 to 2011, quasi-biennial and annual oscillations are clearly visible. A decrease of stratospheric CFC mixing ratios in response to the Montreal Protocol is observed for most altitudes and latitudes. However, the trends differ from the trends measured in the troposphere, they are even positive at some latitudes and altitudes, and can in some cases only be explained by decadal changes in atmospheric age of air spectra or vertical mixing patterns.

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Journal articles on the topic 'CFC-11'

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