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2016
Chipperfield, MP, Liang Q, Rigby M, Hossaini R, Montzka SA, Dhomse S, Feng WH, Prinn RG, Weiss RF, Harth CM, Salameh PK, Muhle J, O'Doherty S, Young D, Simmonds PG, Krummel PB, Fraser PJ, Steele LP, Happell JD, Rhew RC, Butler J, Yvon-Lewis SA, Hall B, Nance D, Moore F, Miller BR, Elkins J, Harrison JJ, Boone CD, Atlas EL, Mahieu E.  2016.  Model sensitivity studies of the decrease in atmospheric carbon tetrachloride. Atmospheric Chemistry and Physics. 16:15741-15754.   10.5194/acp-16-15741-2016   AbstractWebsite

Carbon tetrachloride (CCl4) is an ozone-depleting substance, which is controlled by the Montreal Protocol and for which the atmospheric abundance is decreasing. However, the current observed rate of this decrease is known to be slower than expected based on reported CCl4 emissions and its estimated overall atmospheric lifetime. Here we use a three-dimensional (3-D) chemical transport model to investigate the impact on its predicted decay of uncertainties in the rates at which CCl4 is removed from the atmosphere by photolysis, by ocean uptake and by degradation in soils. The largest sink is atmospheric photolysis (74% of total), but a reported 10% uncertainty in its combined photolysis cross section and quantum yield has only a modest impact on the modelled rate of CCl4 decay. This is partly due to the limiting effect of the rate of transport of CCl4 from the main tropospheric reservoir to the stratosphere, where photolytic loss occurs. The model suggests large interannual variability in the magnitude of this stratospheric photolysis sink caused by variations in transport. The impact of uncertainty in the minor soil sink (9% of total) is also relatively small. In contrast, the model shows that uncertainty in ocean loss (17% of total) has the largest impact on modelled CCl4 decay due to its sizeable contribution to CCl4 loss and large lifetime uncertainty range (147 to 241 years). With an assumed CCl4 emission rate of 39 Gg year(-1), the reference simulation with the best estimate of loss processes still underestimates the observed CCl4 (overestimates the decay) over the past 2 decades but to a smaller extent than previous studies. Changes to the rate of CCl4 loss processes, in line with known uncertainties, could bring the model into agreement with in situ surface and remote-sensing measurements, as could an increase in emissions to around 47 Gg year(-1). Further progress in constraining the CCl4 budget is partly limited by systematic biases between observational datasets. For example, surface observations from the National Oceanic and Atmospheric Administration (NOAA) network are larger than from the Advanced Global Atmospheric Gases Experiment (AGAGE) network but have shown a steeper decreasing trend over the past 2 decades. These differences imply a difference in emissions which is significant relative to uncertainties in the magnitudes of the CCl4 sinks.

Vollmer, MK, Muhle J, Trudinger CM, Rigby M, Montzka SA, Harth CM, Miller BR, Henne S, Krummel PB, Hall BD, Young D, Kim J, Arduini J, Wenger A, Yao B, Reimann S, O'Doherty S, Maione M, Etheridge DM, Li SL, Verdonik DP, Park S, Dutton G, Steele LP, Lunder CR, Rhee TS, Hermansen O, Schmidbauer N, Wang RHJ, Hill M, Salameh PK, Langenfelds RL, Zhou LX, Blunier T, Schwander J, Elkins JW, Butler JH, Simmonds PG, Weiss RF, Prinn RG, Fraser PJ.  2016.  Atmospheric histories and global emissions of halons H-1211 (CBrClF2), H-1301 (CBrF3), and H-2402 (CBrF2CBrF2). Journal of Geophysical Research-Atmospheres. 121:3663-3686.   10.1002/2015jd024488   AbstractWebsite

We report ground-based atmospheric measurements and emission estimates for the halons H-1211 (CBrClF2), H-1301 (CBrF3), and H-2402 (CBrF2CBrF2) from the AGAGE (Advanced Global Atmospheric Gases Experiment) and the National Oceanic and Atmospheric Administration global networks. We also include results from archived air samples in canisters and from polar firn in both hemispheres, thereby deriving an atmospheric record of nearly nine decades (1930s to present). All three halons were absent from the atmosphere until approximate to 1970, when their atmospheric burdens started to increase rapidly. In recent years H-1211 and H-2402 mole fractions have been declining, but H-1301 has continued to grow. High-frequency observations show continuing emissions of H-1211 and H-1301 near most AGAGE sites. For H-2402 the only emissions detected were derived from the region surrounding the Sea of Japan/East Sea. Based on our observations, we derive global emissions using two different inversion approaches. Emissions for H-1211 declined from a peak of 11ktyr(-1) (late 1990s) to 3.9ktyr(-1) at the end of our record (mean of 2013-2015), for H-1301 from 5.4ktyr(-1) (late 1980s) to 1.6ktyr(-1), and for H-2402 from 1.8ktyr(-1) (late 1980s) to 0.38ktyr(-1). Yearly summed halon emissions have decreased substantially; nevertheless, since 2000 they have accounted for approximate to 30% of the emissions of all major anthropogenic ozone depletion substances, when weighted by ozone depletion potentials.

Trudinger, CM, Fraser PJ, Etheridge DM, Sturges WT, Vollmer MK, Rigby M, Martinerie P, Mühle J, Worton DR, Krummel PB, Steele LP, Miller BR, Laube J, Mani FS, Rayner PJ, Harth CM, Witrant E, Blunier T, Schwander J, O'Doherty S, Battle M.  2016.  Atmospheric abundance and global emissions of perfluorocarbons CF4, C2F6 and C3F8 since 1800 inferred from ice core, firn, air archive and in situ measurements. Atmospheric Chemistry and Physics. 16:11733-11754.: Copernicus Publications   10.5194/acp-16-11733-2016   AbstractWebsite
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Simmonds, PG, Rigby M, Manning AJ, Lunt MF, O'Doherty S, McCulloch A, Fraser PJ, Henne S, Vollmer MK, Mühle J, Weiss RF, Salameh PK, Young D, Reimann S, Wenger A, Arnold T, Harth CM, Krummel PB, Steele LP, Dunse BL, Miller BR, Lunder CR, Hermansen O, Schmidbauer N, Saito T, Yokouchi Y, Park S, Li S, Yao B, Zhou LX, Arduini J, Maione M, Wang RHJ, Ivy D, Prinn RG.  2016.  Global and regional emissions estimates of 1,1-difluoroethane (HFC-152a, CH3CHF2) from in situ and air archive observations. Atmospheric Chemistry and Physics. 16:365-382.: Copernicus Publications   10.5194/acp-16-365-2016   AbstractWebsite
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Chirkov, M, Stiller GP, Laeng A, Kellmann S, von Clarmann T, Boone CD, Elkins JW, Engel A, Glatthor N, Grabowski U, Harth CM, Kiefer M, Kolonjari F, Krummel PB, Linden A, Lunder CR, Miller BR, Montzka SA, Mühle J, O'Doherty S, Orphal J, Prinn RG, Toon G, Vollmer MK, Walker KA, Weiss RF, Wiegele A, Young D.  2016.  Global HCFC-22 measurements with MIPAS: retrieval, validation, global distribution and its evolution over 2005–2012. Atmospheric Chemistry and Physics. 16:3345-3368.: Copernicus Publications   10.5194/acp-16-3345-2016   AbstractWebsite
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2015
Lunt, MF, Rigby M, Ganesan AL, Manning AJ, Prinn RG, O’Doherty S, Mühle J, Harth CM, Salameh PK, Arnold T, Weiss RF, Saito T, Yokouchi Y, Krummel PB, Steele PL, Fraser PJ, Li S, Park S, Reimann S, Vollmer MK, Lunder C, Hermansen O, Schmidbauer N, Maione M, Arduini J, Young D, Simmonds PG.  2015.  Reconciling reported and unreported HFC emissions with atmospheric observations. Proceedings of the National Academy of Sciences. 112(9):5927-5931.   10.1073/pnas.1420247112   AbstractWebsite

We infer global and regional emissions of five of the most abundant hydrofluorocarbons (HFCs) using atmospheric measurements from the Advanced Global Atmospheric Gases Experiment and the National Institute for Environmental Studies, Japan, networks. We find that the total CO2-equivalent emissions of the five HFCs from countries that are required to provide detailed, annual reports to the United Nations Framework Convention on Climate Change (UNFCCC) increased from 198 (175–221) Tg-CO2-eq⋅y–1 in 2007 to 275 (246–304) Tg-CO2-eq⋅y–1 in 2012. These global warming potential-weighted aggregated emissions agree well with those reported to the UNFCCC throughout this period and indicate that the gap between reported emissions and global HFC emissions derived from atmospheric trends is almost entirely due to emissions from nonreporting countries. However, our measurement-based estimates of individual HFC species suggest that emissions, from reporting countries, of the most abundant HFC, HFC-134a, were only 79% (63–95%) of the UNFCCC inventory total, while other HFC emissions were significantly greater than the reported values. These results suggest that there are inaccuracies in the reporting methods for individual HFCs, which appear to cancel when aggregated together.

Hossaini, R, Chipperfield MP, Saiz-Lopez A, Harrison JJ, von Glasow R, Sommariva R, Atlas E, Navarro M, Montzka SA, Feng W, Dhomse S, Harth C, Mühle J, Lunder C, O'Doherty S, Young D, Reimann S, Vollmer MK, Krummel PB, Bernath GPFC.  2015.  Growth in stratospheric chlorine from short-lived chemicals not controlled by the Montreal Protocol. Geophysical Research Letters. 42(11):4573-4580.   10.1002/2015gl063783   AbstractWebsite

We have developed a chemical mechanism describing the tropospheric degradation of chlorine-containing very short-lived substances (VSLS). The scheme was included in a global atmospheric model and used to quantify the stratospheric injection of chlorine from anthropogenic VSLS (ClyVSLS) between 2005 to 2013. By constraining the model with surface measurements of chloroform (CHCl3), dichloromethane (CH2Cl2), tetrachloroethene (C2Cl4), trichloroethene (C2HCL3) and 1,2-dichloroethane (CH2ClCH2Cl), we infer a 2013 ClyVSLS mixing ratio of 123 parts per trillion (ppt). Stratospheric injection of source gases dominates this supply, accounting for ~83% of the total. The remainder comes from VSLS-derived organic products, phosgene (COCl2, 7%) and formyl chloride (CHClO, 2%), and also hydrogen chloride (HCl, 8%). Stratospheric ClyVSLS increased by ~52% between 2005-2013, with a mean growth rate of 3.7 ppt Cl/yr. This increase is due to recent and ongoing growth in anthropogenic CH – the most abundant chlorinated VSLS not controlled by the Montreal Protocol.

Rhoderick, GC, Hall BD, Harth CM, Kim JS, Lee J, Montzka SA, Mühle J, Reimann S, Vollmer MK, Weiss RF.  2015.  Comparison of halocarbon measurements in an atmospheric dry whole air sample. Elementa: Science of the Anthropocene. 3:1-13.   10.12952/journal.elementa.000075   Abstract

The growing awareness of climate change/global warming, and continuing concerns regarding stratospheric ozone depletion, will require continued measurements and standards for many compounds, in particular halocarbons that are linked to these issues. In order to track atmospheric mole fractions and assess the impact of policy on emission rates, it is necessary to demonstrate measurement equivalence at the highest levels of accuracy for assigned values of standards. Precise measurements of these species aid in determining small changes in their atmospheric abundance. A common source of standards/scales and/or well-documented agreement of different scales used to calibrate the measurement instrumentation are key to understanding many sets of data reported by researchers. This report describes the results of a comparison study among National Metrology Institutes and atmospheric research laboratories for the chlorofluorocarbons (CFCs) dichlorodifluoromethane (CFC-12), trichlorofluoromethane (CFC-11), and 1,1,2-trichlorotrifluoroethane (CFC-113); the hydrochlorofluorocarbons (HCFCs) chlorodifluoromethane (HCFC-22) and 1-chloro-1,1-difluoroethane (HCFC-142b); and the hydrofluorocarbon (HFC) 1,1,1,2-tetrafluoroethane (HFC-134a), all in a dried whole air sample. The objective of this study is to compare calibration standards/scales and the measurement capabilities of the participants for these halocarbons at trace atmospheric levels. The results of this study show agreement among four independent calibration scales to better than 2.5% in almost all cases, with many of the reported agreements being better than 1.0%.

Johnson, TL, Brahamsha B, Palenik B, Mühle J.  2015.  Halomethane production by vanadium-dependent bromoperoxidase in marine Synechococcus. Limnology and Oceanography. 60:1823-1835.   10.1002/lno.10135   AbstractWebsite

To investigate the role of vanadium-dependent bromoperoxidase (VBPO) for the production of halogenated methanes in marine prokaryotes, we measured VBPO activity and halomethane production in two strains of Synechococcus; one with VBPO (strain CC9311) and one without VBPO (strain WH8102). A mutant strain of CC9311, VMUT2, in which the gene for VBPO is disrupted, was also tested. A suite of halomethanes was measured in the headspace above cultures as well as in the culture medium with a purge-and-trap method. Monohalomethanes were the most consistently produced molecules among the three strains tested. Additionally, CC9311 produced 301 ± 109 molecules cell−1 d−1 of bromoform (CHBr3) when VBPO activity was detected, while production was not significantly different from zero when VBPO activity was not detected. VBPO activity and CHBr3 production were only detected when cultures of CC9311 were stirred, which may contribute to the often moderate to weak correlations between CHBr3 concentration and biological markers in the ocean. No production was seen by VMUT2 or WH8102. These data show that CHBr3 production rates are dramatically increased with or exclusive to the presence of VBPO, supporting its involvement in CHBr3 synthesis. This study thus provides genetic evidence that certain strains of marine Synechococcus, under particular conditions, can be a natural source of marine CHBr3, which contributes to ozone depletion in the stratosphere.

Deeds, DA, Kulongoski JT, Mühle J, Weiss RF.  2015.  Tectonic activity as a significant source of crustal tetrafluoromethane emissions to the atmosphere: Observations in groundwaters along the San Andreas Fault. Earth and Planetary Science Letters. 412:163-172.   http://dx.doi.org/10.1016/j.epsl.2014.12.016   AbstractWebsite

Abstract Tetrafluoromethane (CF4) concentrations were measured in 14 groundwater samples from the Cuyama Valley, Mil Potrero and Cuddy Valley aquifers along the Big Bend section of the San Andreas Fault System (SAFS) in California to assess whether tectonic activity in this region is a significant source of crustal CF4 to the atmosphere. Dissolved CF4 concentrations in all groundwater samples but one were elevated with respect to estimated recharge concentrations including entrainment of excess air during recharge ( C r e ; ∼30 fmol kg−1 H2O), indicating subsurface addition of CF4 to these groundwaters. Groundwaters in the Cuyama Valley contain small CF4 excesses (0.1–9 times C r e ), which may be attributed to an in situ release from weathering and a minor addition of deep crustal CF4 introduced to the shallow groundwater through nearby faults. CF4 excesses in groundwaters within 200 m of the SAFS are larger (10–980 times C r e ) and indicate the presence of a deep crustal flux of CF4 that is likely associated with the physical alteration of silicate minerals in the shear zone of the SAFS. Extrapolating CF4 flux rates observed in this study to the full extent of the SAFS (1300 km × 20–100 km) suggests that the SAFS potentially emits ( 0.3 – 1 ) × 10 − 1 kg CF4 yr−1 to the Earth's surface. For comparison, the chemical weathering of ∼ 7.5 × 10 4 km 2 of granitic rock in California is estimated to release ( 0.019 – 3.2 ) × 10 − 1 kg CF4 yr−1. Tectonic activity is likely an important, and potentially the dominant, driver of natural emissions of CF4 to the atmosphere. Variations in preindustrial atmospheric CF4 as observed in paleo-archives such as ice cores may therefore represent changes in both continental weathering and tectonic activity, including changes driven by variations in continental ice cover during glacial–interglacial transitions.

Dlugokencky, EJ, Hall BD, Montzka SA, Dutton G, Mühle J, Elkins JW.  2015.  [Global Climate, Atmospheric chemical composition] Long-lived greenhouse gases [in State of the Climate in 2014]. Bulletin of the American Meteorological Society. 96( Blunden J, Arndt DS, Eds.).:S39-S42. Abstract
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2014
Fraser, PJ, Krummel PB, Steele LP, Trudinger C, Etheridge DM, Derek N, O’Doherty S, Simmonds PG, Miller BR, Mühle J, Weiss RF, Oram DE, Prinn RG, Wang RHJ.  2014.  Equivalent effective stratospheric chlorine from Cape Grim Air Archive, Antarctic firn and AGAGE global measurements of ozone depleting substances. Baseline atmospheric program 2009-2010. ( Krummel PB, Derek N, Eds.).:17-23.
O'Doherty, S, Rigby M, Muhle J, Ivy DJ, Miller BR, Young D, Simmonds PG, Reimann S, Vollmer MK, Krummel PB, Fraser PJ, Steele LP, Dunse B, Salameh PK, Harth CM, Arnold T, Weiss RF, Kim J, Park S, Li S, Lunder C, Hermansen O, Schmidbauer N, Zhou LX, Yao B, Wang RHJ, Manning AJ, Prinn RG.  2014.  Global emissions of HFC-143a (CH3CF3) and HFC-32 (CH2F2) from in situ and air archive atmospheric observations. Atmospheric Chemistry and Physics. 14:9249-9258.   10.5194/acp-14-9249-2014   AbstractWebsite

High-frequency, in situ observations from the Advanced Global Atmospheric Gases Experiment (AGAGE), for the period 2003 to 2012, combined with archive flask measurements dating back to 1977, have been used to capture the rapid growth of HFC-143a (CH3CF3) and HFC-32 (CH2F2) mole fractions and emissions into the atmosphere. Here we report the first in situ global measurements of these two gases. HFC-143a and HFC-32 are the third and sixth most abundant hydrofluorocarbons (HFCs) respectively and they currently make an appreciable contribution to the HFCs in terms of atmospheric radiative forcing (1.7 +/- 0.04 and 0.7 +/- 0.02 mW m(-2) in 2012 respectively). In 2012 the global average mole fraction of HFC-143a was 13.4 +/- 0.3 ppt (1 sigma) in the lower troposphere and its growth rate was 1.4 +/- 0.04 ppt yr(-1); HFC-32 had a global mean mole fraction of 6.2 +/- 0.2 ppt and a growth rate of 1.1 +/- 0.04 ppt yr(-1) in 2012. The extensive observations presented in this work have been combined with an atmospheric transport model to simulate global atmospheric abundances and derive global emission estimates. It is estimated that 23 +/- 3 Gg yr(-1) of HFC-143a and 21 +/- 11 Gg yr(-1) of HFC-32 were emitted globally in 2012, and the emission rates are estimated to be increasing by 7 +/- 5% yr(-1) for HFC-143a and 14 +/- 11% yr(-1) for HFC-32.

Patra, PK, Krol MC, Montzka SA, Arnold T, Atlas EL, Lintner BR, Stephens BB, Xiang B, Elkins JW, Fraser PJ, Ghosh A, Hintsa EJ, Hurst DF, Ishijima K, Krummel PB, Miller BR, Miyazaki K, Moore FL, Muhle J, O'Doherty S, Prinn RG, Steele LP, Takigawa M, Wang HJ, Weiss RF, Wofsy SC, Young D.  2014.  Observational evidence for interhemispheric hydroxyl-radical parity. Nature. 513:219-+.   10.1038/nature13721   AbstractWebsite

The hydroxyl radical (OH) is a key oxidant involved in the removal of air pollutants and greenhouse gases from the atmosphere(1-3). The ratio of Northern Hemispheric to Southern Hemispheric (NH/SH) OH concentration is important for our understanding of emission estimates of atmospheric species such as nitrogen oxides and methane(4-6). It remains poorly constrained, however, with a range of estimates from 0.85 to 1.4 (refs 4,7-10). Here we determine the NH/SH ratio of OH with the help of methyl chloroform data (a proxy for OH concentrations) and an atmospheric transport model that accurately describes interhemispheric transport and modelled emissions. We find that for the years 2004-2011 the model predicts an annual mean NH-SH gradient of methyl chloroform that is a tight linear function of the modelled NH/SH ratio in annual mean OH. We estimate a NH/SH OH ratio of 0.97 +/- 0.12 during this time period by optimizing global total emissions and mean OH abundance to fit methyl chloroform data from two surface-measurement networks and aircraft campaigns(11-13). Our findings suggest that top-down emission estimates of reactive species such as nitrogen oxides in key emitting countries in the NH that are based on a NH/SH OH ratio larger than 1 may be overestimated.

Fraser, PJ, Dunse BL, Manning AJ, Walsh S, Wang RHJ, Krummel PB, Steele LP, Porter LW, Allison C, O'Doherty S, Simmonds PG, Mühle J, Weiss RF, Prinn RG.  2014.  Australian carbon tetrachloride emissions in a global context. Environmental Chemistry. 11:77-88.   10.1071/EN13171   AbstractWebsite

Global (1978-2012) and Australian (1996-2011) carbon tetrachloride emissions are estimated from atmospheric observations of CCl4 using data from the Advanced Global Atmospheric Gases Experiment (AGAGE) global network, in particular from Cape Grim, Tasmania. Global and Australian emissions are in decline in response to Montreal Protocol restrictions on CCl4 production and consumption for dispersive uses in the developed and developing world. However, atmospheric data-derived emissions are significantly larger than 'bottom-up' estimates from direct and indirect CCl4 production, CCl4 transportation and use. Australian CCl4 emissions are not a result of these sources, and the identification of the origin of Australian emissions may provide a clue to the origin of some of these 'missing' global sources. Journal compilation © CSIRO 2014.

Ganesan, AL, Rigby M, Zammit-Mangion A, Manning AJ, Prinn RG, Fraser PJ, Harth CM, Kim KR, Krummel PB, Li S, Mühle J, O'Doherty SJ, Park S, Salameh PK, Steele LP, Weiss RF.  2014.  Characterization of uncertainties in atmospheric trace gas inversions using hierarchical Bayesian methods. Atmospheric Chemistry and Physics. 14:3855-3864.: Copernicus Publications   10.5194/acp-14-3855-2014   AbstractWebsite
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Arnold, T, Ivy DJ, Harth CM, Vollmer MK, Mühle J, Salameh PK, Steele PL, Krummel PB, Wang RHJ, Young D, Lunder CR, Hermansen O, Rhee TS, Kim J, Reimann S, O'Doherty S, Fraser PJ, Simmonds PG, Prinn RG, Weiss RF.  2014.  HFC-43-10mee atmospheric abundances and global emission estimates. Geophysical Research Letters. :2013GL059143.   10.1002/2013gl059143   AbstractWebsite

We report in situ atmospheric measurements of HFC-43-10mee (C5H2F10, 1,1,1,2,2,3,4,5,5,5-decafluoropentane) from seven observatories at various latitudes, together with measurements of archived air samples and recent Antarctic flask air samples. The global mean tropospheric abundance was 0.21 ± 0.05 ppt (parts-per-trillion, dry air mole fraction) in 2012, rising from 0.04 ± 0.03 ppt in 2000. We combine the measurements with a model and inverse method to estimate rising global emissions –– from 0.43 ± 0.34 Gg yr-1 in 2000 to 1.13 ± 0.31 Gg yr-1 in 2012 (~1.9 Tg CO2-eq yr-1 based on a 100-yr global warming potential of 1,660). HFC-43-10mee –– a cleaning solvent used in the electronics industry –– is currently a minor contributor to global radiative forcing relative to total HFCs; however, our calculated emissions highlight a significant difference from the available reported figures and projected estimates.

Kim, J, Fraser PJ, Li S, Mühle J, Ganesan AL, Krummel PB, Steele PL, Park S, Kim S-K, Park M-K, Arnold T, Harth CM, Salameh PK, Prinn RG, Weiss RF, Kim K-R.  2014.  Quantifying aluminum and semiconductor industry perfluorocarbon emissions from atmospheric measurements. Geophysical Research Letters. 41:2014GL059783.   10.1002/2014gl059783   AbstractWebsite

The potent anthropogenic perfluorocarbon greenhouse gases tetrafluoromethane (CF4) and hexafluoroethane (C2F6) are emitted to the atmosphere mainly by the aluminum and semiconductor industries. Global emissions of these perfluorocarbons (PFCs) calculated from atmospheric measurements are significantly greater than expected from reported national and industry-based emission inventories. In this study, in situ measurements of the two PFCs in the Advanced Global Atmospheric Gases Experiment network are used to show that their emission ratio varies according to the relative regional presence of these two industries, providing an industry-specific emission “signature” to apportion the observed emissions. Our results suggest that underestimated emissions from the global semiconductor industry during 1990–2010, as well as from China's aluminum industry after 2002, account for the observed differences between emissions based on atmospheric measurements and on inventories. These differences are significant despite the large uncertainties in emissions based on the methodologies used by these industries.

Rigby, M, Prinn RG, O'Doherty S, Miller BR, Ivy D, Mühle J, Harth CM, Salameh PK, Arnold T, Weiss RF, Krummel PB, Steele LP, Fraser PJ, Young D, Simmonds PG.  2014.  Recent and future trends in synthetic greenhouse gas radiative forcing. Geophysical Research Letters. :2013GL059099.   10.1002/2013gl059099   AbstractWebsite

Atmospheric measurements show that emissions of hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) are now the primary drivers of the positive growth in synthetic greenhouse gas (SGHG) radiative forcing. We infer recent SGHG emissions and examine the impact of future emissions scenarios, with a particular focus on proposals to reduce HFC use under the Montreal Protocol. If these proposals are implemented, overall SGHG radiative forcing could peak at around 355 mW m-2 in 2020, before declining by approximately 26% by 2050, despite continued growth of fully fluorinated greenhouse gas emissions. Compared to “no HFC policy” projections, this amounts to a reduction in radiative forcing of between 50 and 240 mW m-2 by 2050, or a cumulative emissions saving equivalent to 0.5 to 2.8 years of CO2 emissions at current levels. However, more complete reporting of global HFC emissions is required, as less than half of global emissions are currently accounted for.

Hall, BD, Engel A, Mühle J, Elkins JW, Artuso F, Atlas E, Aydin M, Blake D, Brunke EG, Chiavarini S, Fraser PJ, Happell J, Krummel PB, Levin I, Loewenstein M, Maione M, Montzka SA, O'Doherty S, Reimann S, Rhoderick G, Saltzman ES, Scheel HE, Steele LP, Vollmer MK, Weiss RF, Worthy D, Yokouchi Y.  2014.  Results from the International Halocarbons in Air Comparison Experiment (IHALACE). Atmos. Meas. Tech.. 7:469-490.: Copernicus Publications   10.5194/amt-7-469-2014   AbstractWebsite
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Li, S, Kim J, Park S, Kim S-K, Park M-K, Muhle J, Lee G, Lee M, Jo CO, Kim K-R.  2014.  Source Identification and Apportionment of Halogenated Compounds Observed at a Remote Site in East Asia. Environmental Science & Technology. 48:491-498.: American Chemical Society   10.1021/es402776w   Abstract

The sources of halogenated compds. in East Asia assocd. with stratospheric ozone depletion and climate change are relatively poorly understood. High-precision in situ measurements of 18 halogenated compds. and carbonyl sulfide (COS) made at Gosan, Jeju Island, Korea, from Nov. 2007 to Dec. 2011 were analyzed by a pos. matrix factorization (PMF). Seven major industrial sources were identified from the enhanced concns. of halogenated compds. obsd. at Gosan and corresponding concn.-based source contributions were also suggested: primary aluminum prodn. explaining 37% of total concn. enhancements, solvent usage of which source apportionment is 25%, fugitive emissions from HCFC/HFC prodn. with 11%, refrigerant replacements (9%), semiconductor/electronics industry (9%), foam blowing agents (6%), and fumigation (3%). Statistical trajectory anal. was applied to specify the potential emission regions for seven sources using back trajectories. Primary aluminum prodn., solvent usage and fugitive emission sources were mainly contributed by China. Semiconductor/electronics sources were dominantly located in Korea. Refrigerant replacement, fumigation and foam blowing agent sources were spread throughout East Asian countries. The specified potential source regions are consistent with country-based consumptions and emission patterns, verifying the PMF anal. results. The industry-based emission sources of halogenated compds. identified in this study help improve our understanding of the East Asian countries' industrial contributions to halogenated compd. emissions. [on SciFinder(R)]

Mahieu, E, Zander R, Toon GC, Vollmer MK, Reimann S, Mühle J, Bader W, Bovy B, Lejeune B, Servais C, Demoulin P, Roland G, Bernath PF, Boone CD, Walker KA, Duchatelet P.  2014.  Spectrometric monitoring of atmospheric carbon tetrafluoride (CF4) above the Jungfraujoch station since 1989: evidence of continued increase but at a slowing rate. Atmos. Meas. Tech.. 7:333-344.: Copernicus Publications   10.5194/amt-7-333-2014   AbstractWebsite
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Carpenter, LJ, Reimann S, Burkholder JB, Clerbaux C, Hall BD, Hossaini R, Laube JC, Yvon-Lewis SA, Blake DR, Dorf M, Dutton GS, Fraser PJ, Froidevaux L, Hendrick F, Hu J, Jones A, Krummel PB, Kuijpers LJM, Kurylo MJ, Liang Q, Mahieu E, Mühle J, O'Doherty S, Ohnishi K, Orkin VL, Pfeilsticker K, Rigby M, Simpson IJ, Yokouchi Y, Engel A, Montzka SA.  2014.  Update on Ozone-Depleting Substances (ODSs) and Other Gases of Interest to the Montreal Protocol (Chapter 1). Scientific Assessment of Ozone Depletion: 2014. , Geneva, Switzerland: Global Ozone Research and Monitoring Project-Report No. 55, World Meteorological Organization Abstract
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2013
Ganesan, AL, Chatterjee A, Prinn RG, Harth CM, Salameh PK, Manning AJ, Hall BD, Mühle J, Meredith LK, Weiss RF, O'Doherty S, Young D.  2013.  The variability of methane, nitrous oxide and sulfur hexafluoride in Northeast India. Atmospheric Chemistry and Physics. 13(21):10633-10644.   10.5194/acp-13-10633-2013  
Hall, BD, Dlugokencky EJ, Montzka SA, Dutton G, Mühle J, Elkins JW.  2013.  [Global Climate, Atmospheric composition, Atmospheric Chemical Composition] Long-lived greenhouse gases. State of the Climate in 2012, Bull. Am. Meteor. Soc., 94(8), S31-33.