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Park, Sunyoung,Li, Shanlan,Mü,hle, Jens,O&,apos,Doherty, Simon,Weiss, Ray F.,Fang, Xuekun,Reimann, Stefan,Prinn, Ronald G. Copernicus GmbH 2018 Atmospheric chemistry and physics Vol.18 No.16
<P>Abstract. Carbon tetrachloride (CCl4) is a first-generation ozone-depleting substance, and its emissive use and production were globally banned by the Montreal Protocol with a 2010 phase-out; however, production and consumption for non-dispersive use as a chemical feedstock and as a process agent are still allowed. This study uses the high frequency and magnitude of CCl4 pollution events from an 8-year real-time atmospheric measurement record obtained at Gosan station (a regional background monitoring site in East Asia) to present evidence of significant unreported emissions of CCl4. Top-down emissions of CCl4 amounting to 23.6±7.1 Gg yr−1 from 2011 to 2015 are estimated for China, in contrast to the most recently reported, post-2010, Chinese bottom-up emissions of 4.3-5.2 Gg yr−1. The missing emissions (∼19 Gg yr−1) for China contribute to approximately 54 % of global CCl4 emissions. It is also shown that 89 %±6 % of CCl4 enhancements observed at Gosan are related to CCl4 emissions from the production of CH3Cl, CH2Cl2, CHCl3 and C2Cl4 and its usage as a feedstock and process agent in chemical manufacturing industries. Specific sources and processes are identified using statistical methods, and it is considered highly unlikely that CCl4 is emitted by dispersive uses such as old landfills, contaminated soils and solvent usage. It is thus crucial to implement technical improvements and better regulation strategies to reduce evaporative losses of CCl4 occurring at the factory and/or process levels. </P>
Reconciling reported and unreported HFC emissions with atmospheric observations
Lunt, Mark F.,Rigby, Matthew,Ganesan, Anita L.,Manning, Alistair J.,Prinn, Ronald G.,O’Doherty, Simon,Mü,hle, Jens,Harth, Christina M.,Salameh, Peter K.,Arnold, Tim,Weiss, Ray F.,Saito, Takuya,Y National Academy of Sciences 2015 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.112 No.19
<P><B>Significance</B></P><P>Hydrofluorocarbons (HFCs) are among the atmosphere’s fastest growing, and most potent, greenhouse gases. Proposals have been made to phase down their use over the coming decades. Such initiatives may largely be informed by existing emissions inventories, which, we show, are the subject of significant uncertainty. In this work, we use atmospheric models and measurements to examine the accuracy of these inventories for five major HFCs. We show that, when aggregated together, reported emissions of these HFCs from developed countries are consistent with the atmospheric measurements, and almost half of global emissions now originate from nonreporting countries. However, the agreement between our results and the inventory breaks down for individual HFC emissions, suggesting inaccuracies in the reporting methods for individual compounds.</P><P>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 CO<SUB>2</SUB>-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-CO<SUB>2</SUB>-eq⋅y<SUP>–1</SUP> in 2007 to 275 (246–304) Tg-CO<SUB>2</SUB>-eq⋅y<SUP>–1</SUP> 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.</P>
Inverse modelling of CF4 and NF3 emissions in East Asia
Arnold, Tim,Manning, Alistair J.,Kim, Jooil,Li, Shanlan,Webster, Helen,Thomson, David,Mü,hle, Jens,Weiss, Ray F.,Park, Sunyoung,O&,apos,Doherty, Simon Copernicus GmbH 2018 Atmospheric Chemistry and Physics Vol.18 No.18
<P>Abstract. Decadal trends in the atmospheric abundances of carbon tetrafluoride (CF4) and nitrogen trifluoride (NF3) have been well characterised and have provided a time series of global total emissions. Information on locations of emissions contributing to the global total, however, is currently poor. We use a unique set of measurements between 2008 and 2015 from the Gosan station, Jeju Island, South Korea (part of the Advanced Global Atmospheric Gases Experiment network), together with an atmospheric transport model, to make spatially disaggregated emission estimates of these gases in East Asia. Due to the poor availability of good prior information for this study, our emission estimates are largely influenced by the atmospheric measurements. Notably, we are able to highlight emission hotspots of NF3 and CF4 in South Korea due to the measurement location. We calculate emissions of CF4 to be quite constant between the years 2008 and 2015 for both China and South Korea, with 2015 emissions calculated at 4.3±2.7 and 0.36±0.11 Gg yr−1, respectively. Emission estimates of NF3 from South Korea could be made with relatively small uncertainty at 0.6±0.07 Gg yr−1 in 2015, which equates to ∼1.6 % of the country's CO2 emissions. We also apply our method to calculate emissions of CHF3 (HFC-23) between 2008 and 2012, for which our results find good agreement with other studies and which helps support our choice in methodology for CF4 and NF3. </P>
Rapid increase in ozone-depleting chloroform emissions from China
Fang, Xuekun,Park, Sunyoung,Saito, Takuya,Tunnicliffe, Rachel,Ganesan, Anita L.,Rigby, Matthew,Li, Shanlan,Yokouchi, Yoko,Fraser, Paul J.,Harth, Christina M.,Krummel, Paul B.,Mü,hle, Jens,O’Dohert Springer Science and Business Media LLC 2019 Nature geoscience Vol.12 No.2