Publications

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Book Chapter
Forster, P, Ramaswamy V, Artaxo P, Berntsen J, Betts R, Fahey DW, Haywood J, Lean J, Lowe DC, Myhre G, Nganga J, Prinn R, Raga G, Schulz M, van Dorland R, Bodeker G, Boucher O, Collins WD, Conway TJ, Dlugokencky E, Elkins JW, Etheridge D, Foukal P, Fraser P, Geller M, Joos F, Keeling CD, Keeling R, Kinne S, Lassey K, Lohmann U, Manning AC, Montzka SA, Oram D, O'Shaughnessy K, Piper SC, Plattner GK, Ponater M, Ramankutty N, Reid GC, Rind D, Rosenlof KH, Sausen R, Schwarzkopf D, Solanki SK, Stenchikov G, Stuber N, Takemura T, Textor C, Wang R, Weiss R, Whorf T.  2007.  Changes in atmospheric constituents and in radiative forcing. Climate Change 2007 : The Physical Science Basis : Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. ( Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt K, Tignor M, Miller H, Eds.).:129-234., Cambridge; New York: Cambridge University Press Abstract

For policymakers -- Technical summary -- Historical overview of climate change science -- Changes in atmospheric constituents and radiative forcing -- Observations: atmospheric surface and climate change -- Observations: changes in snow, ice, and frozen ground -- Observations: ocean climate change and sea level -- Paleoclimate -- Coupling between changes in the climate system and biogeochemistry -- Climate models and their evaluation -- Understanding and attributing climate change -- Global climate projections -- Regional climate projections -- Annex I: Glossary -- Annex II: Contributors to the IPCC WGI Fourth Assessment Report -- Annex III: Reviewers of the IPCC WGI Fourth Assessment Report -- Annex IV: Acronyms.

Montzka, SA, Fraser PJ, Butler JH, Connell PS, Cunnold DM, Daniel JS, Derwent RG, Lal S, McCulloch A, Oram D, Reeves CE, Sanhueza E, Steele LP, Velders GJM, Weiss RF, Zander R.  2003.  Controlled substances and other source gases. Scientific assessment of ozone depletion, 2002 (World Meteorological Organization, Global Ozone Research and Monitoring Project, Report 47). :83., Washington, DC: National Oceanic and Atmospheric Administration Abstract
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Carmack, EC, Weiss RF.  1991.  Convection in Lake Baikal: an example of thermobaric instability. Deep Convection and Deep Water Formation in the Oceans. ( Chu PC, Gascard JC, Eds.).:215-228., Burlington: Elsevier Abstract

This book contains articles presenting current knowledge about the formation and renewal of deep waters in the ocean. These articles were presented at an international workshop at the Naval Postgraduate School in Monterey in March 1990.

Weiss, RF.  1969.  Dissolved argon, nitrogen and total carbonate in the Red Sea brines. Hot brines and recent heavy metal deposits in the Red Sea; a geochemical and geophysical account. ( Degens ET, Ross DA, Eds.).:254-260., New York: Springer-Verlag Abstract
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Clerbaux, C, Cunnold DM, Anderson J, Engel AEJ, Fraser PJ, Mahieu E, Manning A, Miller J, Montzka SA, Nassar R, Prinn R, Reimann S, Rinsland CP, Simmonds P, Verdonik D, Weiss R, Wuebbles D, Yokouchi K.  2007.  Long-lived compounds. Scientific assessment of ozone depletion, 2006 (World Meteorological Organization, Global Ozone Research and Monitoring Project, Report 50). :83., Geneva, Switzerland: World Meteorological Organization Abstract
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Prinn, RG, Zander R, Cunnold DM, Elkins JW, Engel A, Fraser PJ, Gunson MR, Ko MKW, Mahieu E, Midgley PM, Russel III JM, Volk CM, Weiss RF.  1999.  Long-lived ozone-related compounds. Scientific assessment of ozone depletion, 1998 (World Meteorological Organization, Global Ozone Research and Monitoring Project Report 44). :54., Washington, DC: National Oceanic and Atmospheric Administration Abstract
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Penkett, SA, Butler JH, Kurylo MJ, Reeves CE, Rodriguez JM, Singh H, Toohey D, Weiss R.  1995.  Methyl bromide. Scientific assessment of ozone depletion: 1994 (World Meterological Organization, Global Ozone Research and Monitoring Report). ( World Meteorological O, Ed.).:26., Geneva, Switzerland; Nairobi, Kenya; Washington, DC, USA: World Meteorological Organization Abstract
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Kurylo, MJ, Rodriguez JM, Andreae MO, Atlas EL, Blake DR, Butler JH, Lal S, Lary DJ, Midgley PM, Montzka SA, Novelli PC, Reeves CE, Simmonds PG, Steele LP, Sturges WT, Weiss RF, Yokouchi Y.  1999.  Short-lived ozone-related compounds. Scientific assessment of ozone depletion, 1998 (World Meteorological Organization, Global Ozone Research and Monitoring Project Report 44). :56., Washington, DC: National Oceanic and Atmospheric Administration Abstract
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Vollmer, MK, Weiss RF, Bootsma HA.  2002.  Ventilation of Lake Malawi/Nyasa. The East African great lakes limnology, palaeolimnology, and biodiversity. ( Odada EO, Olago DO, Eds.).:209-233., Dordrecht; Boston, MA: Kluwer Academic Publishers Abstract
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Conference Proceedings
Weiss, RF, Kirsten OH, Ackermann R, Ramo S.  1977.  Free vehicle instrumentation for the in-situ measurement of processes controlling the formation of deep-sea ferromanganese nodules. OCEANS '77 Conference Record. , New York, N.Y., United States (USA): Inst. Electric. and Electron. Eng., New York, N.Y.   10.1109/OCEANS.1977.1154352   Abstract

This paper describes the free vehicle instrumentation under development for the Manganese Nodule Program (MANOP) of the International Decade for Ocean Exploration (IDOE). Principal emphasis is being placed on the MANOP Bottom Lander, a device designed to carry out in situ chemical flux experiments at the seawater-sediment interface at depths up to 6 km. This device will collect time-series water samples from three separate bottom chamber experiments, each of which can be spiked with various chemical and radioisotopic tracers. The device will also make oxygen and pH measurements in each chamber and will take box core samples under each chamber before returning to the surface. All operations will be microprocessor-controlled with data storage capability and with an acoustic data-link to the surface. Deployments will be for periods of up to 1 year.

Journal Article
Petrenko, VV, Smith AM, Brook EJ, Lowe D, Riedel K, Brailsford G, Hua Q, Schaefer H, Reeh N, Weiss RF, Etheridge D, Severinghaus JP.  2009.  14CH4 measurements in Greenland ice: investigating last glacial termination CH4 sources. Science. 324:506-508.   10.1126/science.1168909   AbstractWebsite

The cause of a large increase of atmospheric methane concentration during the Younger Dryas-Preboreal abrupt climatic transition (similar to 11,600 years ago) has been the subject of much debate. The carbon-14 (C-14) content of methane ((CH4)-C-14) should distinguish between wetland and clathrate contributions to this increase. We present measurements of (CH4)-C-14 in glacial ice, targeting this transition, performed by using ice samples obtained from an ablation site in west Greenland. Measured (CH4)-C-14 values were higher than predicted under any scenario. Sample (CH4)-C-14 appears to be elevated by direct cosmogenic C-14 production in ice. C-14 of CO was measured to better understand this process and correct the sample (CH4)-C-14. Corrected results suggest that wetland sources were likely responsible for the majority of the Younger Dryas-Preboreal CH4 rise.

Simmonds, PG, Derwent RG, Manning AJ, Fraser PJ, Krummel PB, O'Doherty S, Prinn RG, Cunnold DM, Miller BR, Wang HJ, Ryall DB, Porter LW, Weiss RF, Salameh PK.  2004.  AGAGE observations of methyl bromide and methyl chloride at Mace Head, Ireland, and Cape Grim, Tasmania, 1998-2001. Journal of Atmospheric Chemistry. 47:243-269.   10.1023/B:JOCH.0000021136.52340.9c   AbstractWebsite

In situ AGAGE GC-MS measurements of methyl bromide (CH3Br) and methyl chloride (CH3Cl) at Mace Head, Ireland and Cape Grim, Tasmania (1998-2001) reveal a complex pattern of sources. At Mace Head both gases have well-defined seasonal cycles with similar average annual decreases of 3.0% yr(-1) (CH3Br) and 2.6% yr(-1) (CH3Cl), and mean northern hemisphere baseline mole fractions of 10.37 +/- 0.05 ppt and 535.7 +/- 2.2 ppt, respectively. We have used a Lagrangian dispersion model and local meteorological data to segregate the Mace Head observations into different source regions, and interpret the results in terms of the known sources and sinks of these two key halocarbons. At Cape Grim CH3Br and CH3Cl also show annual decreases in their baseline mixing ratios of 2.5% yr(-1) and 1.5% yr(-1), respectively. Mean baseline mole fractions were 7.94 +/- 0.03 ppt (CH3Br) and 541.3 +/- 1.1 ppt (CH3Cl). Although CH3Cl has a strong seasonal cycle there is no well-defined seasonal cycle in the Cape Grim CH3Br record. The fact that both gases are steadily decreasing in the atmosphere at both locations implies that a change has occurred which is affecting a common, major source of both gases (possibly biomass burning) and/or their major sink process (destruction by hydroxyl radical).

Zhang, G, Yao B, Vollmer MK, Montzka SA, Mühle J, Weiss RF, O'Doherty S, Li Y, Fang S, Reimann S.  2017.  Ambient mixing ratios of atmospheric halogenated compounds at five background stations in China. Atmospheric Environment. 160:55-69.   10.1016/j.atmosenv.2017.04.017   AbstractWebsite

High precision measurements of three chlorofluorocarbons (CFCs), three hydrochlorofluorocarbons (HCFCs), six hydrofluorocarbons (HFCs), three perfluorocarbons (PFCs), and sulfur hexafluoride (SF6) were made at five Chinese background stations from January 2011 to December 2012. Their station means in the background air were 239.5 ± 0.69 parts-per-trillion dry-air mole fraction mixing ratios (ppt) for CFC-11, 536.5 ± 1.49 ppt for CFC-12, 74.66 ± 0.09 ppt for CFC-113, 232.1 ± 4.77 ppt for HCFC-22, 23.78 ± 0.29 ppt for HCFC-141b, 22.92 ± 0.42 ppt for HCFC-142b, 11.75 ± 0.43 ppt for HFC-125, 71.32 ± 1.35 ppt for HFC-134a, 13.62 ± 0.43 ppt for HFC-143a, 9.10 ± 1.26 ppt for HFC-152a, 25.45 ± 0.1 ppt for HFC-23, 7.28 ± 0.48 ppt for HFC-32, 4.32 ± 0.03 ppt for PFC-116, 0.63 ± 0.04 ppt for PFC-218, 1.36 ± 0.01 ppt for PFC-318, and 7.67 ± 0.03 ppt for SF6, respectively, which were comparable with those measured at the two Northern Hemisphere (NH) AGAGE stations: Mace Head, Ireland (MHD) and Trinidad Head, California, USA (THD). Compared with our results for earlier years from in-situ measurement at SDZ, background-air mixing ratios of CFCs are now declining, while those for HCFCs, HFCs, PFCs, and SF6 are still increasing. The ratios of the number of sampling events in which measured mixing ratios were elevated above background (pollution events) relative to the total sample frequency (POL/SUM) for CFCs, HCFCs, and HFCs were found to be station dependent, generally LAN > SDZ > LFS > XGL > WLG. The enhancement (△, polluted mixing ratios minus background mixing ratios) generally show distinct patterns, with HCFCs (40.7–175.4 ppt) > HFCs (15.8–66.3 ppt)> CFCs (15.8–33.8 ppt)> PFCs (0.1–0.9 ppt) at five stations, especially for HCFC-22 ranging from 36.9 ppt to 138.2 ppt. Combining with the molecular weights, our findings imply biggest emissions of HCFCs in the regions around these Chinese sites compared to HFCs and CFCs, while the smallest of PFCs, consistent with CFCs being phased out and replaced with HCFCs in China. In addition, relative emission strengths (emission was expressed by mole fractions) of these halocarbons in China were inferred as HCFC-22 > HCFC-141b > HFC-134a > HCFC-142b for the Yangtze River Delta (YRD) and as HCFC-22 > HCFC-142b > HCFC-141b ≈ HFC-134a in the North China Plain (NCP).

Stohl, A, Seibert P, Arduini J, Eckhardt S, Fraser P, Greally BR, Lunder C, Maione M, Muhle J, O'Doherty S, Prinn RG, Reimann S, Saito T, Schmidbauer N, Simmonds PG, Vollmer MK, Weiss RF, Yokouchi Y.  2009.  An analytical inversion method for determining regional and global emissions of greenhouse gases: Sensitivity studies and application to halocarbons. Atmospheric Chemistry and Physics. 9:1597-1620.   10.5194/acp-9-1597-2009   AbstractWebsite

A new analytical inversion method has been developed to determine the regional and global emissions of long-lived atmospheric trace gases. It exploits in situ measurement data from three global networks and builds on backward simulations with a Lagrangian particle dispersion model. The emission information is extracted from the observed concentration increases over a baseline that is itself objectively determined by the inversion algorithm. The method was applied to two hydrofluorocarbons (HFC-134a, HFC-152a) and a hydrochlorofluorocarbon (HCFC-22) for the period January 2005 until March 2007. Detailed sensitivity studies with synthetic as well as with real measurement data were done to quantify the influence on the results of the a priori emissions and their uncertainties as well as of the observation and model errors. It was found that the global a posteriori emissions of HFC-134a, HFC-152a and HCFC-22 all increased from 2005 to 2006. Large increases (21%, 16%, 18%, respectively) from 2005 to 2006 were found for China, whereas the emission changes in North America (-9%, 23%, 17%, respectively) and Europe (11%, 11%,-4%, respectively) were mostly smaller and less systematic. For Europe, the a posteriori emissions of HFC-134a and HFC-152a were slightly higher than the a priori emissions reported to the United Nations Framework Convention on Climate Change (UNFCCC). For HCFC-22, the a posteriori emissions for Europe were substantially (by almost a factor 2) higher than the a priori emissions used, which were based on HCFC consumption data reported to the United Nations Environment Programme (UNEP). Combined with the reported strongly decreasing HCFC consumption in Europe, this suggests a substantial time lag between the reported time of the HCFC-22 consumption and the actual time of the HCFC-22 emission. Conversely, in China where HCFC consumption is increasing rapidly according to the UNEP data, the a posteriori emissions are only about 40% of the a priori emissions. This reveals a substantial storage of HCFC-22 and potential for future emissions in China. Deficiencies in the geographical distribution of stations measuring halocarbons in relation to estimating regional emissions are also discussed in the paper. Applications of the inversion algorithm to other greenhouse gases such as methane, nitrous oxide or carbon dioxide are foreseen for the future.

Min, DH, Bullister JL, Weiss RF.  2002.  Anomalous chlorofluorocarbons in the Southern California Borderland Basins. Geophysical Research Letters. 29   10.1029/2002gl015408   AbstractWebsite

During the past two decades, unexpectedly high concentrations of chlorofluorocarbons (CFCs) have been observed in the bottom waters of the Southern California Borderland Basins (SCBB), with relatively constant spatial distribution patterns. In contrast to offshore waters in this region, CFC concentrations below the oxygen minimum layer (OML) in the deep SCBB increase with depth. The uniformity of the bottom-enhanced CFC signals and the near-zero levels of tritium suggest that this feature is likely maintained by release of CFCs from sediments and vertical mixing, and not by dumped CFC-bearing materials or an intrusion of recently ventilated waters. We hypothesize that CFC scavenging processes, either on particulate organic matter or hydrocarbon residues from the adjacent natural seeps, occur in these high-productivity near-surface coastal waters. The subsequent release of CFCs at the bottom boundary layer during the degradation of particulate material may cause the anomalous CFC distributions in the SCBB.

Bullister, JL, Weiss RF.  1983.  Anthropogenic chlorofluoromethanes in the Greenland and Norwegian Seas. Science. 221:265-268.   10.1126/science.221.4607.265   AbstractWebsite

The concentrations of two industrially produced chlorofluoromethanes, CCl3F(F-11) and CCl2F2(F-12), have been measured in the water column and in the marine atmosphere of the Greenland and Norwegian seas. Measurable concentrations of these two chlorofluoromethanes have penetrated to the deep basins of both of these regions, and the general characteristics of their vertical distributions are similar to those of the bomb-produced radioisotopes injected into the atmosphere on a similar time scale. The data have been fitted to a time-dependent box model based on deep convective mixing in the Greenland Sea and lateral exchange between the deep basins. The model calculations for the two chlorofluoromethanes in the Greenland Sea give similar results, with a time scale for deep convection of about 40 years. The time scale for lateral mixing between the deep Greenland Sea and the deep Norwegian Sea is estimated to be 20 to 30 years, although the agreement between the calculations for the two chlorofluoromethanes is limited by analytical uncertainties at the low concentrations found in the deep Norwegian Sea and by uncertainties in the model assumptions.

Craig, H, Weiss RF.  1968.  Argon concentrations in the ocean: A discussion. Earth and Planetary Science Letters. 5:175-&.   10.1016/s0012-821x(68)80036-6   AbstractWebsite

Because of the importance of argon as a conservative gas tracer in the oceans and as the only rare gas measured both by mass spectrometry and gas chromatography, critical evaluation and comparison of data measured by the two methods is essential. The use of isotope dilution methods in the mass-spectrometric analyses has produced essentially identical precision and accuracy as have been obtained by gas chromatography and the latest Pacific data are in good agreement, especially below 1000 meters depth. The recent data of Bieri et al. provide significant new evidence for the processes we have proposed as responsible for extrema in the saturation anomalies. The data are also consistent with calculations of diffusional losses of the rare gases in northward flowing bottom water in the Pacific.

Lefevre, N, Watson AJ, Cooper DJ, Weiss RF, Takahashi T, Sutherland SC.  1999.  Assessing the seasonality of the oceanic sink for CO2 in the northern hemisphere. Global Biogeochemical Cycles. 13:273-286.   10.1029/1999gb900001   AbstractWebsite

Seasonal CO2 fluxes are estimated from quarterly maps of Delta pCO(2) (difference between the oceanic and atmospheric partial pressure of CO2) and associated error maps. Delta pCO(2) maps were interpolated from pCO(2) measurements in the North Atlantic and the North Pacific Oceans using an objective mapping technique. Negative values correspond to an uptake of CO2 by the ocean. The CO2 flux for the North Atlantic Ocean, between 10 degrees N and 80 degrees N, ranges from -0.69 GtC/yr, for the first quarter (January-March), to -0.19 GtC/yr for the third quarter (July-September) using the gas exchange coefficient of Tans et al. [1990], satellite wind speeds, and a correction for the skin effect. On annual average, the North Atlantic ocean (north of 10 degrees N) is a sink of CO2 ranging from -0.23 +/- 0.08 GtC/yr (gas exchange coefficient of Liss and Merlivat [1986] with Esbensen and Kushnir [1981] wind field) to -0.48 +/- 0.17 GtC/yr (gas exchange coefficient of Tans et al. with satellite wind field). The CO2 flux for the North Pacific, between 15 degrees N and 65 degrees N, ranges from -0.66 GtC/yr from April to June to zero from July to September. For the Atlantic, the errors are generally small, that is, less than 0.19 GtC/yr, but for the Pacific considerably larger uncertainties are generated due to the less extensive data coverage. The northern hemisphere ocean (north of 10 degrees N) is a net sink of CO2 to the atmosphere which is stronger in spring (April-June), due to the biological activity, with an estimate of -1.23 +/- 0.40 GtC/yr averaged over this period. The annual mean northern hemisphere ocean flux is -0.86 +/- 0.61 GtC/yr.

Weiss, RF, Bullister JL, Gammon RH, Warner MJ.  1985.  Atmospheric chlorofluoromethanes in the deep equatorial Atlantic. Nature. 314:608-610.   10.1038/314608a0   AbstractWebsite

Waters that leave the surface of the ocean and enter the subsurface circulation contain concentrations of CCl3F (fluorocarbon-11) and CCl2F2 (fluorocarbon-12), which reflects the temporal increases of these industrially produced compounds in the atmosphere. These chlorofluoromethanes (CFMs) are extremely stable in the troposphere and in natural waters, they have no known natural sources, and their histories of release to the atmosphere are fairly well known1. The atmospheric distributions of CCl3F and CCl2F2 are not strongly dependent on latitude2,3, and their surface water concentrations can be expected to come into relatively rapid solubility equilibrium with the atmosphere4. Recent advances in analytical techniques5,6 have made possible the routine use of these CFMs as oceanic tracers on a decadal timescale. The results we report here are from the first detailed surveys of CCl3F and CCl2F2 distributions in the northern and tropical Atlantic Ocean. They show that CFM-bearing waters originating in the region of the Labrador Sea have reached the Equator in a well-defined western-boundary undercurrent located at a depth of about 1.6 km, in the Upper North Atlantic Deep Water. Using a simple dilution model, we calculate that this water has taken about 23 yr to reach the equatorial region, and has been diluted about five-fold by CFM-free waters.

Vollmer, MK, Young D, Trudinger CM, Muhle J, Henne S, Rigby M, Park S, Li S, Guillevic M, Mitrevski B, Harth CM, Miller BR, Reimann S, Yao B, Steele LP, Wyss SA, Lunder CR, Arduini J, McCulloch A, Wu S, Rhee TS, Wang RHJ, Salameh PK, Hermansen O, Hill M, Langenfelds RL, Ivy D, O'Doherty S, Krummel PB, Maione M, Etheridge DM, Zhou LX, Fraser PJ, Prinn RG, Weiss RF, Simmonds PG.  2018.  Atmospheric histories and emissions of chlorofluorocarbons CFC-13 (CClF3), Sigma CFC-114 (C2Cl2F4), and CFC-115 (C2ClF5). Atmospheric Chemistry and Physics. 18:979-1002.   10.5194/acp-18-979-2018   AbstractWebsite

Based on observations of the chlorofluorocarbons CFC-13 (chlorotrifluoromethane), Sigma CFC-114 (combined measurement of both isomers of dichlorotetrafluoroethane), and CFC-115 (chloropentafluoroethane) in atmospheric and firn samples, we reconstruct records of their tropospheric histories spanning nearly 8 decades. These compounds were measured in polar firn air samples, in ambient air archived in canisters, and in situ at the AGAGE (Advanced Global Atmospheric Gases Experiment) network and affiliated sites. Global emissions to the atmosphere are derived from these observations using an inversion based on a 12-box atmospheric transport model. For CFC-13, we provide the first comprehensive global analysis. This compound increased monotonically from its first appearance in the atmosphere in the late 1950s to a mean global abundance of 3.18 ppt (dry-air mole fraction in parts per trillion, pmol mol(-1)) in 2016. Its growth rate has decreased since the mid-1980s but has remained at a surprisingly high mean level of 0.02 ppt yr(-1) since 2000, resulting in a continuing growth of CFC-13 in the atmosphere. Sigma CFC-114 increased from its appearance in the 1950s to a maximum of 16.6 ppt in the early 2000s and has since slightly declined to 16.3 ppt in 2016. CFC-115 increased monotonically from its first appearance in the 1960s and reached a global mean mole fraction of 8.49 ppt in 2016. Growth rates of all three compounds over the past years are significantly larger than would be expected from zero emissions. Under the assumption of unchanging lifetimes and atmospheric transport patterns, we derive global emissions from our measurements, which have remained unexpectedly high in recent years: mean yearly emissions for the last decade (2007-2016) of CFC-13 are at 0.48 +/- 0.15 kt yr(-1) (> 15% of past peak emissions), of 6 CFC-114 at 1.90 +/- 0.84 kt yr(-1) (similar to 10% of peak emissions), and of CFC-115 at 0.80 +/- 0.50 kt yr(-1) (> 5% of peak emissions). Mean yearly emissions of CFC-115 for 2015-2016 are 1.14 +/- 0.50 kt yr(-1) and have doubled compared to the 2007-2010 minimum. We find CFC-13 emissions from aluminum smelters but if extrapolated to global emissions, they cannot account for the lingering global emissions determined from the atmospheric observations. We find impurities of CFC-115 in the refrigerant HFC-125 (CHF2CF3) but if extrapolated to global emissions, they can neither account for the lingering global CFC-115 emissions determined from the atmospheric observations nor for their recent increases. We also conduct regional inversions for the years 2012-2016 for the northeastern Asian area using observations from the Korean AGAGE site at Gosan and find significant emissions for Sigma CFC-114 and CFC-115, suggesting that a large fraction of their global emissions currently occur in northeastern Asia and more specifically on the Chinese mainland.

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.

Vollmer, MK, Miller BR, Rigby M, Reimann S, Muhle J, Krummel PB, O'Doherty S, Kim J, Rhee TS, Weiss RF, Fraser PJ, Simmonds PG, Salameh PK, Harth CM, Wang RHJ, Steele LP, Young D, Lunder CR, Hermansen O, Ivy D, Arnold T, Schmidbauer N, Kim KR, Greally BR, Hill M, Leist M, Wenger A, Prinn RG.  2011.  Atmospheric histories and global emissions of the anthropogenic hydrofluorocarbons HFC-365mfc, HFC-245fa, HFC-227ea, and HFC-236fa. Journal of Geophysical Research-Atmospheres. 116   10.1029/2010jd015309   AbstractWebsite

We report on ground-based atmospheric measurements and emission estimates of the four anthropogenic hydrofluorocarbons (HFCs) HFC-365mfc (CH(3)CF(2)CH(2)CF(3), 1,1,1,3,3-pentafluorobutane), HFC-245fa (CHF(2)CH(2)CF(3), 1,1,1,3,3-pentafluoropropane), HFC-227ea (CF(3)CHFCF(3), 1,1,1,2,3,3,3-heptafluoropropane), and HFC-236fa (CF(3)CH(2)CF(3), 1,1,1,3,3,3-hexafluoropropane). In situ measurements are from the global monitoring sites of the Advanced Global Atmospheric Gases Experiment (AGAGE), the System for Observations of Halogenated Greenhouse Gases in Europe (SOGE), and Gosan (South Korea). We include the first halocarbon flask sample measurements from the Antarctic research stations King Sejong and Troll. We also present measurements of archived air samples from both hemispheres back to the 1970s. We use a two-dimensional atmospheric transport model to simulate global atmospheric abundances and to estimate global emissions. HFC-365mfc and HFC-245fa first appeared in the atmosphere only similar to 1 decade ago; they have grown rapidly to globally averaged dry air mole fractions of 0.53 ppt (in parts per trillion, 10(-12)) and 1.1 ppt, respectively, by the end of 2010. In contrast, HFC-227ea first appeared in the global atmosphere in the 1980s and has since grown to similar to 0.58 ppt. We report the first measurements of HFC-236fa in the atmosphere. This long-lived compound was present in the atmosphere at only 0.074 ppt in 2010. All four substances exhibit yearly growth rates of >8% yr(-1) at the end of 2010. We find rapidly increasing emissions for the foam-blowing compounds HFC-365mfc and HFC-245fa starting in similar to 2002. After peaking in 2006 (HFC-365mfc: 3.2 kt yr(-1), HFC-245fa: 6.5 kt yr(-1)), emissions began to decline. Our results for these two compounds suggest that recent estimates from long-term projections (to the late 21st century) have strongly overestimated emissions for the early years of the projections (similar to 2005-2010). Global HFC-227ea and HFC-236fa emissions have grown to average values of 2.4 kt yr(-1) and 0.18 kt y(r-)1 over the 2008-2010 period, respectively.

Ivy, DJ, Arnold T, Harth CM, Steele LP, Muhle J, Rigby M, Salameh PK, Leist M, Krummel PB, Fraser PJ, Weiss RF, Prinn RG.  2012.  Atmospheric histories and growth trends of C4F10, C5F12, C6F14, C7F16 and C8F18. Atmospheric Chemistry and Physics. 12:4313-4325.   10.5194/acp-12-4313-2012   AbstractWebsite

Atmospheric observations and trends are presented for the high molecular weight perfluorocarbons (PFCs): decafluorobutane (C4F10), dodecafluoropentane (C5F12), tetradecafluorohexane (C6F14), hexadecafluoroheptane (C7F16) and octadecafluorooctane (C8F18). Their atmospheric histories are based on measurements of 36 Northern Hemisphere and 46 Southern Hemisphere archived air samples collected between 1973 to 2011 using the Advanced Global Atmospheric Gases Experiment (AGAGE) 'Medusa' preconcentration gas chromatography-mass spectrometry systems. A new calibration scale was prepared for each PFC, with estimated accuracies of 6.8% for C4F10, 7.8% for C5F12, 4.0% for C6F14, 6.6% for C7F16 and 7.9% for C8F18. Based on our observations the 2011 globally averaged dry air mole fractions of these heavy PFCs are: 0.17 parts-per-trillion (ppt, i.e., parts per 10(12)) for C4F10, 0.12 ppt for C5F12, 0.27 ppt for C6F14, 0.12 ppt for C7F16 and 0.09 ppt for C8F18. These atmospheric mole fractions combine to contribute to a global average radiative forcing of 0.35 mW m(-2), which is 6% of the total anthropogenic PFC radiative forcing (Montzka and Reimann, 2011; Oram et al., 2012). The growth rates of the heavy perfluorocarbons were largest in the late 1990s peaking at 6.2 parts per quadrillion (ppq, i.e., parts per 10(15)) per year (yr) for C4F10, at 5.0 ppq yr(-1) for C5F12 and 16.6 ppq yr(-1) for C6F14 and in the early 1990s for C7F16 at 4.7 ppq yr(-1) and in the mid 1990s for C8F18 at 4.8 ppq yr(-1). The 2011 globally averaged mean atmospheric growth rates of these PFCs are subsequently lower at 2.2 ppq yr(-1) for C4F10, 1.4 ppq yr(-1) for C5F12, 5.0 ppq yr(-1) for C6F14, 3.4 ppq yr(-1) for C7F16 and 0.9 ppq yr(-1) for C8F18. The more recent slowdown in the growth rates suggests that emissions are declining as compared to the 1980s and 1990s.

Li, PY, Muhle J, Montzka SA, Oram DE, Miller BR, Weiss RF, Fraser PJ, Tanhua T.  2019.  Atmospheric histories, growth rates and solubilities in seawater and other natural waters of the potential transient tracers HCFC-22, HCFC-141b, HCFC-142b, HFC-134a, HFC-125, HFC-23, PFC-14 and PFC-116. Ocean Science. 15:33-60.   10.5194/os-15-33-2019   AbstractWebsite

We present consistent annual mean atmospheric histories and growth rates for the mainly anthropogenic halogenated compounds HCFC-22, HCFC-141b, HCFC-142b, HFC-134a, HFC-125, HFC-23, PFC-14 and PFC-116, which are all potentially useful oceanic transient tracers (tracers of water transport within the ocean), for the Northern and Southern Hemisphere with the aim of providing input histories of these compounds for the equilibrium between the atmosphere and surface ocean. We use observations of these halogenated compounds made by the Advanced Global Atmospheric Gases Experiment (AGAGE), the Scripps Institution of Oceanography (SIO), the Commonwealth Scientific and Industrial Research Organization (CSIRO), the National Oceanic and Atmospheric Administration (NOAA) and the University of East Anglia (UEA). Prior to the direct observational record, we use archived air measurements, firn air measurements and published model calculations to estimate the atmospheric mole fraction histories. The results show that the atmospheric mole fractions for each species, except HCFC-14 lb and HCFC-142b, have been increasing since they were initially produced. Recently, the atmospheric growth rates have been decreasing for the HCFCs (HCFC-22, HCFC-141b and HCFC-142b), increasing for the HFCs (HFC-134a, HFC-125, HFC-23) and stable with little fluctuation for the PFCs (PFC-14 and PFC-116) investigated here. The atmospheric histories (source functions) and natural background mole fractions show that HCFC-22, HCFC-141b, HCFC-142b, HFC-134a, HFC-125 and HFC-23 have the potential to be oceanic transient tracers for the next few decades only because of the recently imposed bans on production and consumption. When the atmospheric histories of the compounds are not monotonically changing, the equilibrium atmospheric mole fraction (and ultimately the age associated with that mole fraction) calculated from their concentration in the ocean is not unique, reducing their potential as transient tracers. Moreover, HFCs have potential to be oceanic transient tracers for a longer period in the future than HCFCs as the growth rates of HFCs are increasing and those of HCFCs are decreasing in the background atmosphere. PFC-14 and PFC-116, however, have the potential to be tracers for longer periods into the future due to their extremely long lifetimes, steady atmospheric growth rates and no explicit ban on their emissions. In this work, we also derive solubility functions for HCFC-22, HCFC-14 lb, HCFC-142b, HFC-134a, HFC-125, HFC-23, PFC-14 and PFC-116 in water and seawater to facilitate their use as oceanic transient tracers. These functions are based on the Clark-Glew-Weiss (CGW) water solubility function fit and salting-out coefficients estimated by the poly-parameter linear free-energy relationships (pp-LFERs). Here we also provide three methods of seawater solubility estimation for more compounds. Even though our intention is for application in oceanic research, the work described in this paper is potentially useful for tracer studies in a wide range of natural waters, including freshwater and saline lakes, and, for the more stable compounds, groundwaters.

Dalsoren, SB, Myhre CL, Myhre G, Gomez-Pelaez AJ, Sovde OA, Isaksen ISA, Weiss RF, Harth CM.  2016.  Atmospheric methane evolution the last 40 years. Atmospheric Chemistry and Physics. 16:3099-3126.   10.5194/acp-16-3099-2016   AbstractWebsite

Observations at surface sites show an increase in global mean surface methane (CH4) of about 180 parts per billion (ppb) (above 10 %) over the period 1984-2012. Over this period there are large fluctuations in the annual growth rate. In this work, we investigate the atmospheric CH4 evolution over the period 1970-2012 with the Oslo CTM3 global chemical transport model (CTM) in a bottom-up approach. We thoroughly assess data from surface measurement sites in international networks and select a subset suited for comparisons with the output from the CTM. We compare model results and observations to understand causes for both long-term trends and short-term variations. Employing Oslo CTM3 we are able to reproduce the seasonal and year-to-year variations and shifts between years with consecutive growth and stagnation, both at global and regional scales. The overall CH4 trend over the period is reproduced, but for some periods the model fails to reproduce the strength of the growth. The model overestimates the observed growth after 2006 in all regions. This seems to be explained by an overly strong increase in anthropogenic emissions in Asia, having global impact. Our findings confirm other studies questioning the timing or strength of the emission changes in Asia in the EDGAR v4.2 emission inventory over recent decades. The evolution of CH4 is not only controlled by changes in sources, but also by changes in the chemical loss in the atmosphere and soil uptake. The atmospheric CH4 lifetime is an indicator of the CH4 loss. In our simulations, the atmospheric CH4 lifetime decreases by more than 8 % from 1970 to 2012, a significant reduction of the residence time of this important greenhouse gas. Changes in CO and NOx emissions, specific humidity, and ozone column drive most of this, and we provide simple prognostic equations for the relations between those and the CH4 lifetime. The reduced lifetime results in substantial growth in the chemical CH4 loss (relative to its burden) and dampens the CH4 growth.