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Keir, RS, Michel RL, Weiss RF.  1992.  Ocean mixing versus gas-exchange in Antarctic Shelf Waters near 150°E. Deep-Sea Research Part a-Oceanographic Research Papers. 39:97-119. AbstractWebsite

In February 1985, chlorofluoromethanes (CFMs), tritium and radiocarbon were measured in Antarctic continental shelf waters near 150-degrees-E. These distributions are used to evaluate (1) the transport of Warm Deep Water (WDW) and Antarctic Surface Water onto the shelf, and (2) the gas exchange rates across the sea surface. The time varying response of these tracers to atmospheric forcing is simulated with a box model of the water masses in this region. In the model, horizontal mixing of surface waters strongly affects the shelf radiocarbon level, but the CFMs and tritium are not affected. The observed low tritium concentrations (< 0.2 TU) in the shelf waters provide a lower limit to the transport of tritium deficient Warm Deep Water into the region, which is equivalent to a vertical flux of about 75 m y-1. This implies a maximum residence time of WDW in the basin of about 8 years. The transport of subsurface water out of the basin at the shelf break is estimated to be approximately 0.2 to 0.4 x 10(6) m3 s-1. The average annual CFM piston velocity for gas exchange is estimated to be about 200 m y-1.

Jacobs, SS, Weiss RF.  1998.  Ocean, ice, and atmosphere : interactions at the Antarctic continental margin. Antarctic Research Series. :380., Washington, D.C.: American Geophysical Union Abstract
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Xiao, X, Prinn RG, Simmonds PG, Steele LP, Novelli PC, Huang J, Langenfelds RL, O'Doherty S, Krummel PB, Fraser PJ, Porter LW, Weiss RF, Salameh P, Wang RHJ.  2007.  Optimal estimation of the soil uptake rate of molecular hydrogen from the Advanced Global Atmospheric Gases Experiment and other measurements. Journal of Geophysical Research-Atmospheres. 112   10.1029/2006jd007241   AbstractWebsite

[1] Hydrogen (H(2)), a proposed clean energy alternative, warrants detailed investigation of its global budget and future environmental impacts. The magnitudes and seasonal cycles of the major ( presumably microbial) soil sink of hydrogen have been estimated from high-frequency in situ AGAGE H(2) observations and also from more geographically extensive but low-frequency flask measurements from CSIRO and NOAA-GMD using the Kalman filter in a two-dimensional (2-D) global transport model. Hydrogen mole fractions exhibit well-defined seasonal cycles in each hemisphere with their phase difference being only about 3 months. The global production rate of H(2) is estimated to be 103 +/- 10 Tg yr(-1) with only a small estimated interannual variation. Soil uptake ( 84 +/- 8 Tg yr(-1)) represents the major loss process for H(2) and accounts for 81% of the total destruction. Strong seasonal cycles are deduced for the soil uptake of H(2). The soil sink is a maximum over the northern extratropics in summer and peaks only 2 to 3 months earlier in the Northern Hemisphere than in the Southern Hemisphere. Oxidation by tropospheric OH (18 +/- 3 Tg yr(-1)) accounts for 17% of the destruction, with the remainder due to destruction in the stratosphere. The calculated global burden is 191 +/- 29 Tg, indicating an overall atmospheric lifetime of 1.8 +/- 0.3 years. Hydrogen in the troposphere ( 149 +/- 23 Tg burden) has a lifetime of 1.4 +/- 0.2 years.

Xiao, X, Prinn RG, Fraser PJ, Simmonds PG, Weiss RF, O'Doherty S, Miller BR, Salameh PK, Harth CM, Krummel PB, Porter LW, Muhle J, Greally BR, Cunnold D, Wang R, Montzka SA, Elkins JW, Dutton GS, Thompson TM, Butler JH, Hall BD, Reimann S, Vollmer MK, Stordal F, Lunder C, Maione M, Arduini J, Yokouchi Y.  2010.  Optimal estimation of the surface fluxes of methyl chloride using a 3-D global chemical transport model. Atmospheric Chemistry and Physics. 10:5515-5533.   10.5194/acp-10-5515-2010   AbstractWebsite

Methyl chloride (CH(3)Cl) is a chlorine-containing trace gas in the atmosphere contributing significantly to stratospheric ozone depletion. Large uncertainties in estimates of its source and sink magnitudes and temporal and spatial variations currently exist. GEIA inventories and other bottom-up emission estimates are used to construct a priori maps of the surface fluxes of CH(3)Cl. The Model of Atmospheric Transport and Chemistry (MATCH), driven by NCEP interannually varying meteorological data, is then used to simulate CH(3)Cl mole fractions and quantify the time series of sensitivities of the mole fractions at each measurement site to the surface fluxes of various regional and global sources and sinks. We then implement the Kalman filter (with the unit pulse response method) to estimate the surface fluxes on regional/global scales with monthly resolution from January 2000 to December 2004. High frequency observations from the AGAGE, SOGE, NIES, and NOAA/ESRL HATS in situ networks and low frequency observations from the NOAA/ESRL HATS flask network are used to constrain the source and sink magnitudes. The inversion results indicate global total emissions around 4100 +/- 470 Ggyr(-1) with very large emissions of 2200 +/- 390 Gg yr(-1) from tropical plants, which turn out to be the largest single source in the CH(3)Cl budget. Relative to their a priori annual estimates, the inversion increases global annual fungal and tropical emissions, and reduces the global oceanic source. The inversion implies greater seasonal and interannual oscillations of the natural sources and sink of CH(3)Cl compared to the a priori. The inversion also reflects the strong effects of the 2002/2003 globally widespread heat waves and droughts on global emissions from tropical plants, biomass burning and salt marshes, and on the soil sink.

Bender, M, Jahnke R, Weiss R, Martin W, Heggie DT, Orchardo J, Sowers T.  1989.  Organic carbon oxidation and benthic nitrogen and silica dynamics in San Clemente Basin, a continental borderland site. Geochimica Et Cosmochimica Acta. 53:685-697.   10.1016/0016-7037(89)90011-2   AbstractWebsite

Organic carbon oxidation rates in San Clemente Basin were determined by benthic chamber experiments using the Bottom Lander, along with studies of pore water chemistry. Non-steady-state diagenetic models are developed for interpreting concentration-time data from the benthic chamber experiments. O2, NO3−, and SO42− are all important oxidants for organic carbon at our study site. Regenerated fixed nitrogen was consumed by NO3− reduction. There is a flux of NO3− into the sediments, and the benthic flux of NH4+ is undetectable. The total rate at which fixed nitrogen is removed from the oceans at this site is about twice the flux of PON to the sea floor. SiO2 fluxes calculated from interfacial pore water gradients are in satisfactory agreement with those determined using the Lander. Most silica dissolution must therefore occur within the sediments, although interstitial profiles show that little dissolution occurs below 1 cm depth.

Kim, J, Li S, Muhle J, Stohl A, Kim SK, Park S, Park MK, Weiss RF, Kim KR.  2012.  Overview of the findings from measurements of halogenated compounds at Gosan (Jeju Island, Korea) quantifying emissions in East Asia. Journal of Integrative Environmental Sciences. 9:71-80.   10.1080/1943815x.2012.696548   AbstractWebsite

With increased economic growth in East Asia, regional emissions of many anthropogenic halogenated compounds now constitute a substantial fraction of the global totals. Here, we summarize recently reported findings from measurements of a wide range of chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6), and other halogenated compounds at Gosan (Jeju Island, Korea) within the advanced global atmospheric gases experiment (AGAGE). General wind patterns at Gosan bring air masses from the surrounding areas, allowing the monitoring of both clean baseline and polluted air masses. We have analyzed our measurements since November 2007 both with an interspecies correlation method and with an inversion method based on the FLEXPART Lagrangian particle dispersion model to estimate these regional emissions. The results show that emissions of halogenated compounds in East Asia account for over 20% of global emissions, both in terms of ozone depletion potential (ODP) and global warming potential (GWP), and emphasize the importance of atmospheric measurements for quantifying emissions of these compounds in this region.

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Muhle, J, Ganesan AL, Miller BR, Salameh PK, Harth CM, Greally BR, Rigby M, Porter LW, Steele LP, Trudinger CM, Krummel PB, O'Doherty S, Fraser PJ, Simmonds PG, Prinn RG, Weiss RF.  2010.  Perfluorocarbons in the global atmosphere: tetrafluoromethane, hexafluoroethane, and octafluoropropane. Atmospheric Chemistry and Physics. 10:5145-5164.   10.5194/acp-10-5145-2010   AbstractWebsite

We present atmospheric baseline growth rates from the 1970s to the present for the long-lived, strongly infrared-absorbing perfluorocarbons (PFCs) tetrafluoromethane (CF(4)), hexafluoroethane (C(2)F(6)), and octafluoropropane (C(3)F(8)) in both hemispheres, measured with improved accuracies (similar to 1-2%) and precisions (<0.3%, or <0.2 ppt (parts per trillion dry air mole fraction), for CF(4); <1.5%, or <0.06 ppt, for C(2)F(6); <4.5%, or <0.02 ppt, for C3F8) within the Advanced Global Atmospheric Gases Experiment (AGAGE). Pre-industrial background values of 34.7 +/- 0.2 ppt CF(4) and 0.1 +/- 0.02 ppt C(2)F(6) were measured in air extracted from Greenland ice and Antarctic firn. Anthropogenic sources are thought to be primary aluminum production (CF(4), C(2)F(6), C(3)F(8)), semiconductor production (C(2)F(6), CF(4), C(3)F(8)) and refrigeration use (C(3)F(8)). Global emissions calculated with the AGAGE 2-D 12-box model are significantly higher than most previous emission estimates. The sum of CF(4) and C(2)F(6) emissions estimated from aluminum production and non-metal production are lower than observed global top-down emissions, with gaps of similar to 6 Gg/yr CF(4) in recent years. The significant discrepancies between previous CF(4), C(2)F(6), and C(3)F(8) emission estimates and observed global top-down emissions estimated from AGAGE measurements emphasize the need for more accurate, transparent, and complete emission reporting, and for verification with atmospheric measurements to assess the emission sources of these long-lived and potent greenhouse gases, which alter the radiative budget of the atmosphere, essentially permanently, once emitted.

Mühle, J, Trudinger CM, Western LM, Rigby M, Vollmer MK, Park S, Manning AJ, Say D, Ganesan A, Steele LP, Ivy DJ, Arnold T, Li S, Stohl A, Harth CM, Salameh PK, McCulloch A, O'Doherty S, Park MK, Jo CO, Young D, Stanley KM, Krummel PB, Mitrevski B, Hermansen O, Lunder C, Evangeliou N, Yao B, Kim J, Hmiel B, Buizert C, Petrenko VV, Arduini J, Maione M, Etheridge DM, Michalopoulou E, Czerniak M, Severinghaus JP, Reimann S, Simmonds PG, Fraser PJ, Prinn RG, Weiss RF.  2019.  Perfluorocyclobutane (PFC-318, c-C4F8) in the global atmosphere. Atmos. Chem. Phys.. 19:10335-10359.: Copernicus Publications   10.5194/acp-19-10335-2019   Abstract

We reconstruct atmospheric abundances of the potent greenhouse gas c-C4F8 (perfluorocyclobutane, perfluorocarbon PFC-318) from measurements of in situ, archived, firn, and aircraft air samples with precisions of ∼1 %–2 % reported on the SIO-14 gravimetric calibration scale. Combined with inverse methods, we found near-zero atmospheric abundances from the early 1900s to the early 1960s, after which they rose sharply, reaching 1.66 ppt (parts per trillion dry-air mole fraction) in 2017. Global c-C4F8 emissions rose from near zero in the 1960s to 1.2±0.1 (1σ) Gg yr−1 in the late 1970s to late 1980s, then declined to 0.77±0.03 Gg yr−1 in the mid-1990s to early 2000s, followed by a rise since the early 2000s to 2.20±0.05 Gg yr−1 in 2017. These emissions are significantly larger than inventory-based emission estimates. Estimated emissions from eastern Asia rose from 0.36 Gg yr−1 in 2010 to 0.73 Gg yr−1 in 2016 and 2017, 31 % of global emissions, mostly from eastern China. We estimate emissions of 0.14 Gg yr−1 from northern and central India in 2016 and find evidence for significant emissions from Russia. In contrast, recent emissions from northwestern Europe and Australia are estimated to be small (≤1 % each). We suggest that emissions from China, India, and Russia are likely related to production of polytetrafluoroethylene (PTFE, “Teflon”) and other fluoropolymers and fluorochemicals that are based on the pyrolysis of hydrochlorofluorocarbon HCFC-22 (CHClF2) in which c-C4F8 is a known by-product. The semiconductor sector, where c-C4F8 is used, is estimated to be a small source, at least in South Korea, Japan, Taiwan, and Europe. Without an obvious correlation with population density, incineration of waste-containing fluoropolymers is probably a minor source, and we find no evidence of emissions from electrolytic production of aluminum in Australia. While many possible emissive uses of c-C4F8 are known and though we cannot categorically exclude unknown sources, the start of significant emissions may well be related to the advent of commercial PTFE production in 1947. Process controls or abatement to reduce the c-C4F8 by-product were probably not in place in the early decades, explaining the increase in emissions in the 1960s and 1970s. With the advent of by-product reporting requirements to the United Nations Framework Convention on Climate Change (UNFCCC) in the 1990s, concern about climate change and product stewardship, abatement, and perhaps the collection of c-C4F8 by-product for use in the semiconductor industry where it can be easily abated, it is conceivable that emissions in developed countries were stabilized and then reduced, explaining the observed emission reduction in the 1980s and 1990s. Concurrently, production of PTFE in China began to increase rapidly. Without emission reduction requirements, it is plausible that global emissions today are dominated by China and other developing countries. We predict that c-C4F8 emissions will continue to rise and that c-C4F8 will become the second most important emitted PFC in terms of CO2-equivalent emissions within a year or two. The 2017 radiative forcing of c-C4F8 (0.52 mW m−2) is small but emissions of c-C4F8 and other PFCs, due to their very long atmospheric lifetimes, essentially permanently alter Earth's radiative budget and should be reduced. Significant emissions inferred outside of the investigated regions clearly show that observational capabilities and reporting requirements need to be improved to understand global and country-scale emissions of PFCs and other synthetic greenhouse gases and ozone-depleting substances.

Vollmer, MK, Weiss RF, Williams RT, Falkner KK, Qiu X, Ralph EA, Romanovsky VV.  2002.  Physical and chemical properties of the waters of saline lakes and their importance for deep-water renewal: Lake Issyk-Kul, Kyrgyzstan. Geochimica Et Cosmochimica Acta. 66:4235-4246.   10.1016/s0016-7037(02)01052-9   AbstractWebsite

The relationships between electrical conductivity, temperature, salinity, and density are studied for brackish Lake Issyk-Kul. These studies are based on a newly determined major ion composition, which for the open lake shows a mean absolute salinity of 6.06 g kg(-1). The conductivity-temperature relationship of the lake water was determined experimentally showing that the lake water is about 1.25 times less conductive than seawater diluted to the same absolute salinity as that of the lake water. Based on these results, an algorithm is presented to calculate salinity from in-situ conductivity measurements. Applied to the field data, this shows small but important vertical salinity variations in the lake with a salinity maximum at 200 m and a freshening of the surface water with increasing proximity to the shores. The algorithm we adopt to calculate density agrees well with earlier measurements and shows that at 20degreesC and I atm Lake Issyk-Kul water is about 530 g m(-3) denser than seawater at the same salinity. The temperature of maximum density at I atm is about 0.15degreesC lower than that for seawater diluted to the same salinity. Despite its small variations, salinity plays an important role, together with temperature changes, in the static stability and in the production of deep-water in this lake. Changes in salinity may have had important consequences on the mixing regime and the fate of inflowing river water over geological time. Uncharged silicic acid is negligible for the stability of the water column except near an similar to15 m thick nepheloid layer observed at the bottom of the deep basin. Copyright (C) 2002 Elsevier Science Ltd.

Weiss, RF.  1968.  Piggyback sampler for dissolved gas studies on sealed water samples. Deep-Sea Research. 15:695-699.   10.1016/0011-7471(68)90082-x   AbstractWebsite

A sampler which obtains leak-proof sealed water samples from any depth has been developed for the study of dissolved gases. Closing of the sampler is activated by the tripping of the Nansen bottle to which it is attached. The water collected by the sampler is thus taken at the same time and place at which the Nansen bottle measures thermometric depth and temperature and collects water for measurement of salinity and other properties. Other advantages include ease of operation and low cost. The sampler has been tested at sea under a wide range of conditions.

Weiss, RF, Craig H.  1973.  Precise shipboard determination of dissolved nitrogen, oxygen, argon, and total inorganic carbon by gas chromatography. Deep-Sea Research. 20:291-303.   10.1016/0011-7471(73)90054-5   AbstractWebsite

A seagoing gas chromatographic system for the rapid and precise determination of dissolved gases in sea water is described. Separate instruments are employed for total inorganic carbon, and for nitrogen, oxygen, and argon analyses. Factors affecting the design, calibration, and shipboard operation of the system are discussed in detail. Results of intercomparisons with other analytical techniques confirm the accuracy of the gas chromatographic method. Profiles of ΣCO2, O2, and N2 measured aboard ship are presented and discussed.

Weiss, RF, Craig H.  1976.  Production of atmospheric nitrous oxide by combustion. Geophysical Research Letters. 3:751-753.   10.1029/GL003i012p00751   AbstractWebsite

Measurements of N2O in the effluent gases from the burning of coal and fuel oil show that these are significant anthropogenic sources of atmospheric N2O. We estimate that the present global production of N2O from these sources is 1.6 Mtons N2O(N) per year and is increasing at a rate of ∼ 3.5% per year. Catalytic converters for the reduction of NO emissions also represent a major potential source of atmospheric N2O.

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Kim, J, Fraser PJ, Li S, Muhle J, Ganesan AL, Krummel PB, Steele LP, Park S, Kim SK, Park MK, Arnold T, Harth CM, Salameh PK, Prinn RG, Weiss RF, Kim KR.  2014.  Quantifying aluminum and semiconductor industry perfluorocarbon emissions from atmospheric measurements. Geophysical Research Letters. 41:4787-4794.   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.

Weiss, RF, Prinn RG.  2011.  Quantifying greenhouse-gas emissions from atmospheric measurements: a critical reality check for climate legislation. Philosophical Transactions of the Royal Society a-Mathematical Physical and Engineering Sciences. 369:1925-1942.   10.1098/rsta.2011.0006   AbstractWebsite

Emissions reduction legislation relies upon 'bottom-up' accounting of industrial and biogenic greenhouse-gas (GHG) emissions at their sources. Yet, even for relatively well-constrained industrial GHGs, global emissions based on 'top-down' methods that use atmospheric measurements often agree poorly with the reported bottom-up emissions. For emissions reduction legislation to be effective, it is essential that these discrepancies be resolved. Because emissions are regulated nationally or regionally, not globally, top-down estimates must also be determined at these scales. High-frequency atmospheric GHG measurements at well-chosen station locations record 'pollution events' above the background values that result from regional emissions. By combining such measurements with inverse methods and atmospheric transport and chemistry models, it is possible to map and quantify regional emissions. Even with the sparse current network of measurement stations and current inverse-modelling techniques, it is possible to rival the accuracies of regional 'bottom-up' emission estimates for some GHGs. But meeting the verification goals of emissions reduction legislation will require major increases in the density and types of atmospheric observations, as well as expanded inverse-modelling capabilities. The cost of this effort would be minor when compared with current investments in carbon-equivalent trading, and would reduce the volatility of that market and increase investment in emissions reduction.

Nevison, CD, Lueker TJ, Weiss RF.  2004.  Quantifying the nitrous oxide source from coastal upwelling. Global Biogeochemical Cycles. 18   10.1029/2003gb002110   AbstractWebsite

A continuous record of atmospheric N2O measured from a tower in northern California captures strong pulses of N2O released by coastal upwelling events. The atmospheric record offers a unique, observation-based method for quantifying the coastal N2O source. A coastal upwelling model is developed and compared to the constraints imposed by the atmospheric record in the Pacific Northwest coastal region. The upwelling model is based on Ekman theory and driven by high-resolution wind and SST data and by relationships between subsurface N2O and temperature. A simplified version of the upwelling model is extended to the world's major eastern boundary regions to estimate a total coastal upwelling source of similar to0.2 +/- >70% Tg N2O-N/yr. This flux represents similar to5% of the total ocean source, estimated here at similar to4 Tg N2O-N/yr using traditional gas-transfer methods, and is probably largely neglected in current N2O budgets.

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Chan, LH, Edmond JM, Stallard RF, Broecker WS, Chung YC, Weiss RF, Ku TL.  1976.  Radium and barium at Geosecs stations in Atlantic and Pacific. Earth and Planetary Science Letters. 32:258-267.   10.1016/0012-821x(76)90066-2   AbstractWebsite

Ra and Ba show a general linear correlation in the oceanic water column within the uncertainties of the data: the slope of the line is about 4.6 nanomoles (nmoles) Ra/mole Ba, the intercept being at about 4 nmoles Ba/kg. This demonstrates the usefulness of Ba as a “chemical analogue” of Ra. Box-model calculations indicate that the average deep-water excess of Ra over Ba should be about 10% relative to the surface. This is consistent with the observations outside the deep northeast Pacific. However, the uncertainties in the data are such that the regional variation in the primary input cannot be resolved. In the deep waters of the North Pacific there is in fact a large excess of Ra relative to Ba. The one detailed profile presently available (204) can be explained consistently by a simple vertical advection-diffusion model.

O'Doherty, S, Cunnold DM, Manning A, Miller BR, Wang RHJ, Krummel PB, Fraser PJ, Simmonds PG, McCulloch A, Weiss RF, Salameh P, Porter LW, Prinn RG, Huang J, Sturrock G, Ryall D, Derwent RG, Montzka SA.  2004.  Rapid growth of hydrofluorocarbon 134a and hydrochlorofluorocarbons 141b, 142b, and 22 from Advanced Global Atmospheric Gases Experiment (AGAGE) observations at Cape Grim, Tasmania, and Mace Head, Ireland. Journal of Geophysical Research-Atmospheres. 109   10.1029/2003jd004277   AbstractWebsite

[1] An update of in situ Advanced Global Atmospheric Gases Experiment (AGAGE) hydrofluorocarbon (HFC)/hydrochlorofluorocarbon ( HCFC) measurements made at Mace Head, Ireland, and Cape Grim, Tasmania, from 1998 to 2002 are reported. HCFC-142b, HCFC-141b, HCFC-22 and HFC-134a show continued rapid growth in the atmosphere at mean rates of 1.1, 1.6, 6.0, and 3.4 ppt/year, respectively. Emissions inferred from measurements are compared to recent estimates from consumption data. Minor updates to the industry estimates of emissions are reported together with a discussion of how to best determine OH concentrations from these trace gas measurements. In addition, AGAGE measurements and derived emissions are compared to those deduced from NOAA-Climate Monitoring and Diagnostics Laboratory flask measurements ( which are mostly made at different locations). European emission estimates obtained from Mace Head pollution events using the Nuclear Accident Model ( NAME) dispersion model and the best fit algorithm ( known as simulated annealing) are presented as 3-year rolling average emissions over Europe for the period 1999-2001. Finally, the measurements of HCFC-141b, HCFC-142b, and HCFC-22 discussed in this paper have been combined with the Atmospheric Lifetime Experiment (ALE)/Global Atmospheric Gases Experiment (GAGE)/AGAGE measurements of CFC-11, CFC-12, CFC-113, CCl4, and CH3CCl3 to produce the evolution of tropospheric chlorine loading.

Fang, XK, Park S, Saito T, Tunnicliffe R, Ganesan AL, Rigby M, Li SL, Yokouchi Y, Fraser PJ, Harth CM, Krummel PB, Muhle J, O'Doherty S, Salameh PK, Simmonds PG, Weiss RF, Young D, Lunt MF, Manning AJ, Gressentl A, Prinn RG.  2019.  Rapid increase in ozone-depleting chloroform emissions from China. Nature Geoscience. 12:89-+.   10.1038/s41561-018-0278-2   AbstractWebsite

Chloroform contributes to the depletion of the stratospheric ozone layer. However, due to its short lifetime and predominantly natural sources, it is not included in the Montreal Protocol that regulates the production and uses of ozone-depleting substances. Atmospheric chloroform mole fractions were relatively stable or slowly decreased during 1990-2010. Here we show that global chloroform mole fractions increased after 2010, based on in situ chloroform measurements at seven stations around the world. We estimate that the global chloroform emissions grew at the rate of 3.5% yr(-1) between 2010 and 2015 based on atmospheric model simulations. We used two regional inverse modelling approaches, combined with observations from East Asia, to show that emissions from eastern China grew by 49 (41-59) Gg between 2010 and 2015, a change that could explain the entire increase in global emissions. We suggest that if chloroform emissions continuously grow at the current rate, the recovery of the stratospheric ozone layer above Antarctica could be delayed by several years.

Rigby, M, Prinn RG, O'Doherty S, Montzka SA, McCulloch A, Harth CM, Muhle J, Salameh PK, Weiss RF, Young D, Simmonds PG, Hall BD, Dutton GS, Nance D, Mondeel DJ, Elkins JW, Krummel PB, Steele LP, Fraser PJ.  2013.  Re-evaluation of the lifetimes of the major CFCs and CH3CCl3 using atmospheric trends. Atmospheric Chemistry and Physics. 13:2691-2702.   10.5194/acp-13-2691-2013   AbstractWebsite

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 usin!

Rigby, M, Prinn RG, O'Doherty S, Miller BR, Ivy D, Muhle 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. 41:2623-2630.   10.1002/2013gl059099   AbstractWebsite

Atmospheric measurements show that emissions of hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons 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 355mWm(-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 240mWm(-2) by 2050 or a cumulative emissions saving equivalent to 0.5 to 2.8years 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.

Simmonds, PG, Rigby M, McCulloch A, Vollmer MK, Henne S, Muhle J, O'Doherty S, Manning AJ, Krummel PB, Fraser PJ, Young D, Weiss RF, Salameh PK, Harth CM, Reimann S, Trudinger CM, Steele LP, Wang RHJ, Ivy DJ, Prinn RG, Mitrevski B, Etheridge DM.  2018.  Recent increases in the atmospheric growth rate and emissions of HFC-23 (CHF3) and the link to HCFC-22 (CHClF2) production. Atmospheric Chemistry and Physics. 18:4153-4169.   10.5194/acp-18-4153-2018   AbstractWebsite

High frequency measurements of trifluoromethane (HFC-23, CHF3), a potent hydrofluorocarbon greenhouse gas, largely emitted to the atmosphere as a by-product of the production of the hydrochlorofluorocarbon HCFC-22 (CHClF2), at five core stations of the Advanced Global Atmospheric Gases Experiment (AGAGE) network, combined with measurements on firn air, old Northern Hemisphere air samples and Cape Grim Air Archive (CGAA) air samples, are used to explore the current and historic changes in the atmospheric abundance of HFC-23. These measurements are used in combination with the AGAGE 2-D atmospheric 12-box model and a Bayesian inversion methodology to determine model atmospheric mole fractions and the history of global HFC-23 emissions. The global modelled annual mole fraction of HFC-23 in the background atmosphere was 28.9 +/- 0.6 pmol mol(-1) at the end of 2016, representing a 28% increase from 22.6 +/- 0.4 pmol mol(-1) in 2009. Over the same time frame, the modelled mole fraction of HCFC-22 increased by 19% from 199 +/- 2 to 237 +/- 2 pmol mol(-1). However, unlike HFC-23, the annual average HCFC-22 growth rate slowed from 2009 to 2016 at an annual average rate of -0.5 pmol mol(-1) yr(-2). This slowing atmospheric growth is consistent with HCFC-22 moving from dispersive (high fractional emissions) to feedstock (low fractional emissions) uses, with HFC-23 emissions remaining as a consequence of incomplete mitigation from all HCFC-22 production. Our results demonstrate that, following a minimum in HFC-23 global emissions in 2009 of 9.6 +/- 0.6, emissions increased to a maximum in 2014 of 14.5 +/- 0.6 Gg yr(-1) and then declined to 12.7 +/- 0.6 Gg yr(-1) (157 MtCO(2) eq.yr(-1)) in 2016. The 2009 emissions minimum is consistent with estimates based on national reports and is likely a response to the implementation of the Clean Development Mechanism (CDM) to mitigate HFC-23 emissions by incineration in developing (non-Annex 1) countries under the Kyoto Protocol. Our derived cumulative emissions of HFC-23 during 20102016 were 89 +/- 2 Gg (1.1 +/- 0.2 GtCO(2) eq.), which led to an increase in radiative forcing of 1.0 +/- 0.1mWm(-2) over the same period. Although the CDM had reduced global HFC-23 emissions, it cannot now offset the higher emissions from increasing HCFC-22 production in non-Annex 1 countries, as the CDM was closed to new entrants in 2009. We also find that the cumulative European HFC-23 emissions from 2010 to 2016 were similar to 1.3 Gg, corresponding to just 1.5% of cumulative global HFC-23 emissions over this same period. The majority of the increase in global HFC-23 emissions since 2010 is attributed to a delay in the adoption of mitigation technologies, predominantly in China and East Asia. However, a reduction in emissions is anticipated, when the Kigali 2016 amendment to the Montreal Protocol, requiring HCFC and HFC production facilities to introduce destruction of HFC-23, is fully implemented.

Lunt, MF, Rigby M, Ganesan AL, Manning AJ, Prinn RG, O'Doherty S, Muhle J, Harth CM, Salameh PK, Arnold T, Weiss RF, Saito T, Yokouchi Y, Krummel PB, Steele LP, Fraser PJ, Li SL, 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 of the United States of America. 112:5927-5931.   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.

Walker, SJ, Weiss RF, Salameh PK.  2000.  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. 105:14285-14296.   10.1029/1999jc900273   AbstractWebsite

Annual mean mixing ratios for the halocarbons CFC-11 (CCl3F), CFC-12 (CCl2F2), CFC-113 (CClF2CCl2F), and carbon tetrachloride (CCl4) have been determined from their first year of industrial production through 1998. From the late 1970s (in the case of CFC-11 and CFC-12) or early 1980s tin the case of CFC-113 and carbon tetrachloride) the reported mixing ratios have been determined from experimental observations made by the Atmospheric Lifetime Experiment/Global Atmospheric Gases Experiment/Advanced Global Atmospheric Gases Experiment program. For years prior to these times we have used estimates of industrial emissions and atmospheric lifetimes to calculate historic concentrations. The likely error bounds of the annual mean values are also reported here. Errors in the annual mean mixing ratio may primarily be a result of incorrect industrial emissions data, an incorrect atmospheric lifetime,or uncertainty in the ALE/GAGE/AGAGE observations. Each of these possible sources of error has been considered separately. These results show that atmospheric concentrations for each of these compounds have experienced a rapid rise in the early part of their production. Tt is only within the past decade that rise rates have decreased sharply and (except in the case of CFC-12) in the past few years that atmospheric concentrations have begun to decrease. The uncertainties in the reconstructed histories are a similar proportion for each of the chlorofluorocarbons (<4% for most of the history). However, uncertainty in the history of carbon tetrachloride is much greater (up to 12%, and this is mainly the result of poor knowledge of CCl4 emissions.

Kim, J, Li S, Kim KR, Stohl A, Muhle J, Kim SK, Park MK, Kang DJ, Lee G, Harth CM, Salameh PK, Weiss RF.  2010.  Regional atmospheric emissions determined from measurements at Jeju Island, Korea: Halogenated compounds from China. Geophysical Research Letters. 37   10.1029/2010gl043263   AbstractWebsite

High-frequency in-situ measurements of a wide range of halogenated compounds including chlorofluorocarbons (CFCs), halons, hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), perfluorinated compounds (PFCs), sulfur hexafluoride (SF(6)), and other chlorinated and brominated compounds have been made at Gosan (Jeju Island, Korea). Regional emissions of HCFC-22 (CHClF(2)) calculated from inverse modeling were combined with interspecies correlation methods to estimate national emissions for China, a major emitter of industrial halogenated gases. Our results confirm the signs of successful phase-out of primary ozone-depleting species such as CFCs, halons and many chlorinated or brominated compounds, along with substantial emissions of replacement HCFCs. Emissions derived for HFCs, PFCs, and SF6 were compared to published estimates and found to be a significant fraction of global totals. Overall, Chinese emissions of the halogenated compounds discussed here represent 19(14-17)% and 20(15-26)% of global emissions when evaluated in terms of their Ozone Depletion Potentials and 100-year Global Warming Potentials, respectively. Citation: Kim, J., et al. (2010), Regional atmospheric emissions determined from measurements at Jeju Island, Korea: Halogenated compounds from China, Geophys. Res. Lett., 37, L12801, doi: 10.1029/2010GL043263.

Rigby, M, Prinn RG, Fraser PJ, Simmonds PG, Langenfelds RL, Huang J, Cunnold DM, Steele LP, Krummel PB, Weiss RF, O'Doherty S, Salameh PK, Wang HJ, Harth CM, Muhle J, Porter LW.  2008.  Renewed growth of atmospheric methane. Geophysical Research Letters. 35   10.1029/2008gl036037   AbstractWebsite

Following almost a decade with little change in global atmospheric methane mole fraction, we present measurements from the Advanced Global Atmospheric Gases Experiment (AGAGE) and the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) networks that show renewed growth starting near the beginning of 2007. Remarkably, a similar growth rate is found at all monitoring locations from this time until the latest measurements. We use these data, along with an inverse method applied to a simple model of atmospheric chemistry and transport, to investigate the possible drivers of the rise. Specifically, the relative roles of an increase in emission rate or a decrease in concentration of the hydroxyl radical, the largest methane sink, are examined. We conclude that: 1) if the annual mean hydroxyl radical concentration did not change, a substantial increase in emissions was required simultaneously in both hemispheres between 2006 and 2007; 2) if a small drop in the hydroxyl radical concentration occurred, consistent with AGAGE methyl chloroform measurements, the emission increase is more strongly biased to the Northern Hemisphere. Citation: Rigby, M., et al. (2008), Renewed growth of atmospheric methane, Geophys. Res. Lett., 35, L22805, doi: 10.1029/2008GL036037.