AGAGE measurements of atmospheric trace gases from archived air samples.

AGAGE Air Archive Jens Mühle1, Ben Adam2, Benjamin R. Miller3,4, Diane J. Ivy5, Tim Arnold6, Martin K. Vollmer7, Ray F. Weiss1, Luke M. Western2, M. Rigby2, Paul B. Krummel8, Paul J. Fraser8, L. Paul Steele8, Ray L. Langenfelds8 1.       Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, USA 2.       School of Chemistry, University of Bristol, Bristol, UK 3.       Formerly at Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA 4.       Formerly at Global Monitoring Division, ESRL, NOAA, Boulder, Colorado, USA 5.       Formerly at Center for Global Change Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA 6.       Formerly at Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USA, now at Department of Physical Geography and Ecosystem Science, Lund University, Lund 223 62, Sweden 7.       Laboratory for Air Pollution/Environmental Technology, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland 8.       CSIRO Environment, Aspendale, Victoria, Australia   Measurements of stored air samples from the Southern and Northern Hemisphere have been used to reconstruct the abundance of atmospheric trace gases before in-situ instrumentation at sites of the Advanced Global Atmospheric Gases Experiment (AGAGE) and its predecessors (ALE/GAGE) became operational.   For the Southern Hemisphere (SH), air collection and archiving began in 1978 with the Cape Grim Air Archive (CGAA), where air samples were taken at Kennaook/Cape Grim (CGO, Tasmania, Australia) during clean air conditions. Stainless steel tanks were filled cryogenically with the intention of reconstructing the historical composition of ambient air once suitable analytical instruments and calibration scales were developed (Fraser et al., 1991; Francey et al., 1996; Fraser et al., 2018). Here, we use archived air measurements made with Medusa GC-MS (gas chromatography-mass spectrometry) systems (Miller et al., 2008; Arnold et al., 2012) in 2007 by Ben Miller, Paul Steele and colleagues (e.g., Miller et al., 2010) and in 2011 by Diane Ivy, Paul Steele, Jens Mühle, Tim Arnold and colleagues (e.g., Ivy et al., 2012), which were used in many subsequent studies (e.g., Mühle et al., 2009; O’Doherty et al., 2009; Rigby et al., 2010; O’Doherty et al., 2014) as listed below. These Medusa GC-MS measurements were mostly performed at the CSIRO (Commonwealth Scientific and Industrial Research Organisation) Aspendale laboratory in Australia, but also at the Scripps Institution of Oceanography (SIO), in La Jolla, California USA. The frequency of available CGAA air samples varies with time, with one or two samples per year typically available before 1994, and up to nine samples available per year between 1994-1999. Good agreement between the measurements at SIO and CSIRO of identical air samples and air samples with the same or similar fill dates has been demonstrated in previous publications (Mühle et al., 2008; O'Doherty et al., 2009; Miller et al., 2010).   To complement the CGAA, archived air samples from the Northern Hemisphere (NH) were gathered from several laboratories, mainly the C. D. Keeling, R. F. Keeling, and R. F. Weiss laboratories at SIO, the Global Monitoring Laboratory (GML) at the National Oceanic and Atmospheric Administration (NOAA) in Boulder, the Norwegian Institute for Air Research (NILU) in Oslo, Norway, CSIRO and the University of California at Berkeley (UCB). These samples were mostly measured on Medusa GC-MS systems at SIO. Many of these tanks had been filled at Trinidad Head (THD, California, USA) or SIO (La Jolla, California, USA), some at other northern hemispheric locations in the USA (such as Cape Meares in Oregon, Point Barrow in Alaska, and Niwot Ridge in Colorado) between 1973 and 2016 (Mühle et al., 2009, 2010). Unlike the CGAA, many of these samples were not originally intended for future atmospheric archive measurements and required more stringent quality control. For inert and/or highly volatile or very abundant compounds (such as CF4, SF6, NF3, many HFCs and HCFCs) the resulting measurements were suitable to reconstruct historic northern hemispheric abundances. More outliers had to be removed for other compounds (e.g., for several minor CFCs, H-2402, HCFC-22, -124, HFC-43-10mee, and PFC-218) during data processing using an iterative filtering process, resulting in more uncertain northern hemispheric historic abundances. Some archived air samples from the Northern Hemisphere were also measured at CSIRO (Arnold et al., 2012; Ivy et al., 2012; Mühle et al., 2010, 2009), again generally confirming that measurements from the instruments at SIO and CSIRO can be combined.   This archive contains reprocessed results from these measurements with updated calibrations and iterative filtering applied. Earlier versions of many of these trace gas records have been published but the data were not always provided in numerical format and not in one consistent format or in one place.   Before using these data in any way, first contact Jens Mühle ([email protected]) and Paul B. Krummel ([email protected]) (or, if not available, other appropriate AGAGE and CSIRO contacts).   The code for processing and standardising these data is at https://github.com/qq23840/agage-air-archive, which uses code from https://github.com/AGAGE-atmosphere/agage-archive. These libraries are currently maintained by the University of Bristol. Please contact [email protected] or [email protected] (or other appropriate AGAGE or University of Bristol contacts) with errors and questions.   For questions regarding individual data sources, please contact Jens Mühle ([email protected]) and the relevant AGAGE PIs (contact details are contained in file metadata). Raw and processed data The raw data stem from the records of archive measurements maintained by Jens Mühle at the Scripps Institution of Oceanography (SIO), La Jolla, CA. They are based in part on the original data files provided by Ben Miller and Diane Ivy as well as raw data processing routines provided by Diane Ivy (Bash, Matlab). The iterative filtering process (Matlab) ingests these archive measurements and the pollution free monthly mean abundance of all available in-situ ALE/GAGE/AGAGE measurements (pre-ADS-GC-MS, ADS-GC-MS, pre-GC-MD, GC-MD, and Medusa-GC systems). For questions regarding the measurement, archival process and filtering process, contact Jens Mühle ([email protected]). These data have been updated by applying any new calibration tank values and updated iterative filtering, but largely reflect the mixing ratio used in previous studies. The studies are cited in the metadata of each file and listed below. After this, studies describing the ALE/GAGE/AGAGE network, the Cape Grim Air Archive (CGAA), the Medusa instrument, and the CGAA measurements are provided. 1.  Mühle, J., A. L. Ganesan, B. R. Miller, P. K. Salameh, C. M. Harth, B. R. Greally, M. Rigby, L. W. Porter, L. P. Steele, C. M. Trudinger, P. B. Krummel, S. O'Doherty, P. J. Fraser, P. G. Simmonds, R. G. Prinn, and R. F. Weiss, Perfluorocarbons in the global atmosphere: tetrafluoromethane, hexafluoroethane, and octafluoropropane, Atmos. Chem. Phys., 10(11), 5145-5164, 10.5194/acp-10-5145-2010, 2010. 2.  Trudinger, C. M., P. J. Fraser, D. M. Etheridge, W. T. Sturges, M. K. Vollmer, M. Rigby, P. Martinerie, J. Mühle, D. R. Worton, P. B. Krummel, L. P. Steele, B. R. Miller, J. Laube, F. S. Mani, P. J. Rayner, C. M. Harth, E. Witrant, T. Blunier, J. Schwander, S. O'Doherty, and M. Battle, Atmospheric abundance and global emissions of perfluorocarbons CF4, C2F6 and C3F8 since 1800 inferred from ice core, firn, air archive and in situ measurements, Atmos. Chem. Phys., 16(18), 11733-11754, 10.5194/acp-16-11733-2016, 2016. 3.  Mühle, J., J. Huang, R. F. Weiss, R. G. Prinn, B. R. Miller, P. K. Salameh, C. M. Harth, P. J. Fraser, L. W. Porter, B. R. Greally, S. O'Doherty, P. G. Simmonds, P. B. Krummel, and L. P. Steele, Sulfuryl Fluoride in the Global Atmosphere, J. Geophys. Res., 114(D5), D05306, 10.1029/2008JD011162, 2009. 4.  Rigby, M., J. Mühle, B. R. Miller, R. G. Prinn, P. B. Krummel, L. P. Steele, P. J. Fraser, P. K. Salameh, C. M. Harth, R. F. Weiss, B. R. Greally, S. O'Doherty, P. G. Simmonds, M. K. Vollmer, S. Reimann, J. Kim, K. R. Kim, H. J. Wang, J. G. J. Olivier, E. J. Dlugokencky, G. S. Dutton, B. D. Hall, and J. W. Elkins, History of atmospheric SF6 from 1973 to 2008, Atmos. Chem. Phys., 10(21), 10305-10320, 10.5194/acp-10-10305-2010, 2010. 5.  Simmonds, P. G., M. Rigby, A. J. Manning, S. Park, K. M. Stanley, A. McCulloch, S. Henne, F. Graziosi, M. Maione, J. Arduini, S. Reimann, M. K. Vollmer, J. Mühle, S. O'Doherty, D. Young, P. B. Krummel, P. J. Fraser, R. F. Weiss, P. K. Salameh, C. M. Harth, M. K. Park, H. Park, T. Arnold, C. Rennick, L. P. Steele, B. Mitrevski, R. H. J. Wang, and R. G. Prinn, The increasing atmospheric burden of the greenhouse gas sulfur hexafluoride (SF6), Atmos. Chem. Phys., 20(12), 7271-7290, 10.5194/acp-20-7271-2020, 2020. 6.  Arnold, T., C. M. Harth, J. Mühle, A. J. Manning, P. K. Salameh, J. Kim, D. J. Ivy, L. P. Steele, V. V. Petrenko, J. P. Severinghaus, D. Baggenstos, and R. F. Weiss, Nitrogen trifluoride global emissions estimated from updated atmospheric measurements, Proc. Natl. Acad. Sci., 110(6), 2029-2034, 10.1073/pnas.1212346110, 2013. 7.  Mühle, J., C. M. Trudinger, L. M. Western, M. Rigby, M. K. Vollmer, S. Park, A. J. Manning, D. Say, A. Ganesan, L. P. Steele, D. J. Ivy, T. Arnold, S. Li, A. Stohl, C. M. Harth, P. K. Salameh, A. McCulloch, S. O'Doherty, M. K. Park, C. O. Jo, D. Young, K. M. Stanley, P. B. Krummel, B. Mitrevski, O. Hermansen, C. Lunder, N. Evangeliou, B. Yao, J. Kim, B. Hmiel, C. Buizert, V. V. Petrenko, J. Arduini, M. Maione, D. M. Etheridge, E. Michalopoulou, M. Czerniak, J. P. Severinghaus, S. Reimann, P. G. Simmonds, P. J. Fraser, R. G. Prinn, and R. F. Weiss, Perfluorocyclobutane (PFC-318, c-C4F8) in the global atmosphere, Atmos. Chem. Phys., 19(15), 10335-10359, 10.5194/acp-19-10335-2019, 2019. 8.  Miller, B. R., M. Rigby, L. J. M. Kuijpers, P. B. Krummel, L. P. Steele, M. Leist, P. J. Fraser, A. McCulloch, C. Harth, P. Salameh, J. Mühle, R. F. Weiss, R. G. Prinn, R. H. J. Wang, S. O'Doherty, B. R. Greally, and P. G. Simmonds, HFC-23 (CHF3) emission trend response to HCFC-22 (CHClF2) production and recent HFC-23 emission abatement measures, Atmos. Chem. Phys., 10(16), 7875-7890, 10.5194/acp-10-7875-2010, 2010. 9.  Simmonds, P. G., M. Rigby, A. McCulloch, M. K. Vollmer, S. Henne, J. Mühle, S. O'Doherty, A. J. Manning, P. B. Krummel, P. J. Fraser, D. Young, R. F. Weiss, P. K. Salameh, C. M. Harth, S. Reimann, C. M. Trudinger, P. Steele, R. H. J. Wang, D. J. Ivy, R. G. Prinn, B. Mitrevski, and D. M. Etheridge, Recent increases in the atmospheric growth rate and emissions of HFC-23 (CHF3) and the link to HCFC-22 (CHClF2) production, Atmos. Chem. Phys., 18(6), 4153-4169, 10.5194/acp-18-4153-2018, 2018. 10. Stanley, K. M., D. Say, J. Mühle, C. M. Harth, P. B. Krummel, D. Young, S. J. O’Doherty, P. K. Salameh, P. G. Simmonds, R. F. Weiss, R. G. Prinn, P. J. Fraser, and M. Rigby, Increase in global emissions of HFC-23 despite near-total expected reductions, Nature Commun., 11(1), 397, 10.1038/s41467-019-13899-4, 2020. 11. O'Doherty, S., M. Rigby, J. Mühle, D. J. Ivy, B. R. Miller, D. Young, P. G. Simmonds, S. Reimann, M. K. Vollmer, P. B. Krummel, P. J. Fraser, L. P. Steele, B. Dunse, P. K. Salameh, C. M. Harth, T. Arnold, R. F. Weiss, J. Kim, S. Park, S. Li, C. Lunder, O. Hermansen, N. Schmidbauer, L. X. Zhou, B. Yao, R. H. J. Wang, A. J. Manning, and R. G. Prinn, Global emissions of HFC-143a (CH3CF3) and HFC-32 (CH2F2) from in situ and air archive atmospheric observations, Atmos. 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Montzka, 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, J. Geophys. Res., 109(D6), D06310, 10.1029/2003jd004277, 2004. 14. M. Rigby, R.G. Prinn, S. O'Doherty, B.R. Miller, D. Ivy, J. Mühle, C.M. Harth, P.K. Salameh, T. Arnold, R.F. Weiss, P.B. Krummel, L.P. Steele, P.J. Fraser, D. Young, and P.G. Simmonds: Recent and future trends in synthetic greenhouse gas radiative forcing, Geophys. Res. Lett., 41(7), 2623-2630, 10.1002/2013GL059099, 2014 15. Simmonds, P. G., M. Rigby, A. J. Manning, M. F. Lunt, S. O'Doherty, A. McCulloch, P. J. Fraser, S. Henne, M. K. Vollmer, J. Mühle, R. F. Weiss, P. K. Salameh, D. Young, S. Reimann, A. Wenger, T. Arnold, C. M. Harth, P. B. Krummel, L. P. Steele, B. L. Dunse, B. R. Miller, C. R. Lunder, O. Hermansen, N. Schmidbauer, T. Saito, Y. Yokouchi, S. Park, S. Li, B. Yao, L. X. Zhou, J. Arduini, M. Maione, R. H. J. Wang, D. Ivy, and R. G. Prinn, Global and regional emissions estimates of 1,1-difluoroethane (HFC-152a, CH3CHF2) from in situ and air archive observations, Atmos. Chem. Phys., 16(1), 365-382, 10.5194/acp-16-365-2016, 2016. 16. Vollmer, M. K., B. R. Miller, M. Rigby, S. Reimann, J. Mühle, P. B. Krummel, S. O'Doherty, J. Kim, T. S. Rhee, R. F. Weiss, P. J. Fraser, P. G. Simmonds, P. K. Salameh, C. M. Harth, R. H. J. Wang, L. P. Steele, D. Young, C. R. Lunder, O. Hermansen, D. Ivy, T. Arnold, N. Schmidbauer, K.-R. Kim, B. R. Greally, M. Hill, M. Leist, A. Wenger, and R. G. Prinn, Atmospheric histories and global emissions of the anthropogenic hydrofluorocarbons HFC-365mfc, HFC-245fa, HFC-227ea, and HFC-236fa, J. Geophys. Res., 116(D8), D08304, 10.1029/2010jd015309, 2011. 17. Arnold, T., D. J. Ivy, C. M. Harth, M. K. Vollmer, J. Mühle, P. K. Salameh, L. P. Steele, P. B. Krummel, R. H. J. Wang, D. Young, C. R. Lunder, O. Hermansen, T. S. Rhee, J. Kim, S. Reimann, S. 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Weiss, R. G. Prinn, and S. A. Montzka, A decrease in radiative forcing and equivalent effective chlorine from hydrochlorofluorocarbons, Nature Clim. Change, 14(8), 805-807, 10.1038/s41558-024-02038-7, 2024. 20. Simmonds, P. G., M. Rigby, A. McCulloch, S. O'Doherty, D. Young, J. Mühle, P. B. Krummel, P. Steele, P. J. Fraser, A. J. Manning, R. F. Weiss, P. K. Salameh, C. M. Harth, R. H. J. Wang, and R. G. Prinn, Changing trends and emissions of hydrochlorofluorocarbons (HCFCs) and their hydrofluorocarbon (HFCs) replacements, Atmos. Chem. Phys., 17(7), 4641-4655, 10.5194/acp-17-4641-2017, 2017. 21. Western, L. M., A. L. Redington, A. J. Manning, C. M. Trudinger, L. Hu, S. Henne, X. Fang, L. J. M. Kuijpers, C. Theodoridi, D. S. Godwin, J. Arduini, B. Dunse, A. Engel, P. J. Fraser, C. M. Harth, P. B. Krummel, M. Maione, J. Mühle, S. O'Doherty, H. Park, S. Park, S. Reimann, P. K. Salameh, D. Say, R. Schmidt, T. Schuck, C. Siso, K. M. Stanley, I. Vimont, M. K. Vollmer, D. Young, R. G. Prinn, R. F. Weiss, S. A. Montzka, and M. Rigby, A renewed rise in global HCFC-141b emissions between 2017–2021, Atmos. Chem. Phys., 22(14), 9601-9616, 10.5194/acp-22-9601-2022, 2022. 22. Vollmer, M. K., D. Young, C. M. Trudinger, J. Mühle, S. Henne, M. Rigby, S. Park, S. Li, M. Guillevic, B. Mitrevski, C. M. Harth, B. R. Miller, S. Reimann, B. Yao, L. P. Steele, S. A. Wyss, C. R. Lunder, J. Arduini, A. McCulloch, S. Wu, T. S. Rhee, R. H. J. Wang, P. K. Salameh, O. Hermansen, M. Hill, R. L. Langenfelds, D. Ivy, S. O'Doherty, P. B. Krummel, M. Maione, D. M. Etheridge, L. Zhou, P. J. Fraser, R. G. Prinn, R. F. Weiss, and P. G. Simmonds, Atmospheric histories and emissions of chlorofluorocarbons CFC-13 (CClF3), ΣCFC-114 (C2Cl2F4), and CFC-115 (C2ClF5), Atmos. Chem. Phys., 18(2), 979-1002, 10.5194/acp-18-979-2018, 2018. 23. Fraser, P., D. Cunnold, F. Alyea, R. Weiss, R. Prinn, P. Simmonds, B. Miller, and R. Langenfelds, Lifetime and emission estimates of 1,1,2-trichlorotrifluorethane (CFC-113) from daily global background observations June 1982 June 1994, J. Geophys. Res., 101(D7), 12585-12599, 10.1029/96jd00574, 1996. 24. Fraser, P. J., D. E. Oram, C. E. Reeves, S. A. Penkett, and A. McCulloch, Southern Hemispheric halon trends (1978-1998) and global halon emissions, J. Geophys. Res., 104(D13), 15985-15999, 10.1029/1999jd900113, 1999. 25. Newland, M. J., C. E. Reeves, D. E. Oram, J. C. Laube, W. T. Sturges, C. Hogan, P. Begley, and P. J. Fraser, Southern hemispheric halon trends and global halon emissions, 1978–2011, Atmos. Chem. Phys., 13(11), 5551-5565, 10.5194/acp-13-5551-2013, 2013. 26. Vollmer, M. K., J. Mühle, C. M. Trudinger, M. Rigby, S. A. Montzka, C. M. Harth, B. R. Miller, S. Henne, P. B. Krummel, B. D. Hall, D. Young, J. Kim, J. Arduini, A. Wenger, B. Yao, S. Reimann, S. O'Doherty, M. Maione, D. M. Etheridge, S. Li, D. P. Verdonik, S. Park, G. Dutton, L. P. Steele, C. R. Lunder, T. S. Rhee, O. Hermansen, N. Schmidbauer, R. H. J. Wang, M. Hill, P. K. Salameh, R. L. Langenfelds, L. Zhou, T. Blunier, J. Schwander, J. W. Elkins, J. H. Butler, P. G. Simmonds, R. F. Weiss, R. G. Prinn, and P. J. C. J. D. Fraser, Atmospheric histories and global emissions of halons H-1211 (CBrClF2), H-1301 (CBrF3), and H-2402 (CBrF2CBrF2), J. Geophys. Res., 121(7), 3663-3686, 10.1002/2015jd024488, 2016. 27. Langenfelds, R. L., P. J. Fraser, R. J. Francey, L. P. Steele, L. W. Porter and C. E. Allison, The Cape Grim Air Archive: the first seventeen years, 1978 – 1995, Baseline Atmospheric Program (Australia) 1994-1995, edited by R. J. Francey, A. L. Dick and N. Derek, Bureau of Meteorology and CSIRO Division of Atmospheric Research, Melbourne, Australia, 53-70, 10.4225/08/5865509fa7a35, 1996. Descriptions of the ALE/GAGE/AGAGE network can be found here: 1.  Prinn, R. G., R. F. Weiss, P. J. Fraser, P. G. Simmonds, D. M. Cunnold, F. N. Alyea, S. O'Doherty, P. Salameh, B. R. Miller, J. Huang, R. H. J. Wang, D. E. Hartley, C. Harth, L. P. Steele, G. Sturrock, P. M. Midgley, and A. McCulloch, A history of chemically and radiatively important gases in air deduced from ALE/GAGE/AGAGE, J. Geophys. Res., 105(D14), 17751-17792, 10.1029/2000jd900141, 2000. 2.  Prinn, R. G., R. F. Weiss, J. Arduini, T. Arnold, H. L. DeWitt, P. J. Fraser, A. L. Ganesan, J. Gasore, C. M. Harth, O. Hermansen, J. Kim, P. B. Krummel, S. Li, Z. M. Loh, C. R. Lunder, M. Maione, A. J. Manning, B. R. Miller, B. Mitrevski, J. Mühle, S. O'Doherty, S. Park, S. Reimann, M. Rigby, T. Saito, P. K. Salameh, R. Schmidt, P. G. Simmonds, L. P. Steele, M. K. Vollmer, R. H. Wang, B. Yao, Y. Yokouchi, D. Young, and L. Zhou, History of chemically and radiatively important atmospheric gases from the Advanced Global Atmospheric Gases Experiment (AGAGE), Earth Syst. Sci. Data, 10(2), 985-1018, 10.5194/essd-10-985-2018, 2018.  Website: agage.mit.edu. Descriptions of the Cape Grim Air Archive (CGAA) can be found here: 1.  Fraser, P. J., R. L. Langenfelds, N. Derek, and L. W. Porter, Studies in air archiving techniques, in Baseline Atmospheric Program (Australia) 1989, Department of the Arts, Sport, the Environment, Tourism and Territories, Bureau of Meteorology and CSIRO Division of Atmospheric Research, Canberra, A.C.T., 16-29, 10.4225/08/585eb98106135, 1991. 2.  Francey, R. J., L. P. Steele, R. L. Langenfelds, M. P. Lucarelli, C. E. Allison, D. J. Beardsmore, S. A. Coram, N. Derek, F. R. De Silva, D. M. Etheridge, P. J. Fraser, R. J. Henry, B. Turner, E. D. Welch, D. A. Spencer, and L. N. Cooper, Global Atmospheric Sampling Laboratory (GASLAB): supporting and extending the Cape Grim trace gas programs, in Baseline Atmospheric Program Australia 1993, R. J. Francey, A. L. Dick and N. Derek, Department of the Environment, Sport and Territories, Bureau of Meteorology in cooperation with CSIRO Division of Atmospheric Research, Melbourne, 8-29, 10.4225/08/5862ad5543518, 1996. 3. Langenfelds, R. L., P. J. Fraser, R. J. Francey, L. P. Steele, L. W. Porter and C. E. Allison, The Cape Grim Air Archive: the first seventeen years, 1978 – 1995, Baseline Atmospheric Program (Australia) 1994-1995, edited by R. J. Francey, A. L. Dick and N. Derek, Bureau of Meteorology and CSIRO Division of Atmospheric Research, Melbourne, Australia, 53-70, 10.4225/08/5865509fa7a35, 1996. 4.  Fraser, P. J., G. I. Pearman, and N. Derek, CSIRO Non-carbon Dioxide Greenhouse Gas Research. Part 1: 1975-90, Hist. Rec. Aust. Sci., 29(1), 1-13, 10.1071/HR17016, 2018. Descriptions of the Medusa instrument can be found here: 1.  Miller, B. R., R. F. Weiss, P. K. Salameh, T. Tanhua, B. R. Greally, J. Mühle, and P. G. Simmonds, Medusa: A sample preconcentration and GC/MS detector system for in situ measurements of atmospheric trace halocarbons, hydrocarbons, and sulfur compounds, Anal. Chem., 80(5), 1536-1545, 10.1021/ac702084k, 2008. 2.  Arnold, T., J. Mühle, P. K. Salameh, C. M. Harth, D. J. Ivy, and R. F. Weiss, Automated measurement of nitrogen trifluoride in ambient air, Anal. Chem., 84(11), 4798−4804, 10.1021/ac300373e, 2012. 1.  Descriptions of the CGAA measurements can be found here: Miller, B. R., M. Rigby, L. J. M. Kuijpers, P. B. Krummel, L. P. Steele, M. Leist, P. J. Fraser, A. McCulloch, C. Harth, P. Salameh, J. Mühle, R. F. Weiss, R. G. Prinn, R. H. J. Wang, S. O'Doherty, B. R. Greally, and P. G. Simmonds, HFC-23 (CHF3) emission trend response to HCFC-22 (CHClF2) production and recent HFC-23 emission abatement measures, Atmos. Chem. Phys., 10(16), 7875-7890, 10.5194/acp-10-7875-2010, 2010. 2.  Ivy, D. J., T. Arnold, C. M. Harth, L. P. Steele, J. Mühle, M. Rigby, P. K. Salameh, M. Leist, P. B. Krummel, P. J. Fraser, R. F. Weiss, and R. G. Prinn, Atmospheric histories and growth trends of C4F10, C5F12, C6F14, C7F16 and C8F18, Atmos. Chem. Phys., 12(9), 4313-4325, 10.5194/acp-12-4313-2012, 2012.   Format and Structure This archive consists of a set of netCDF files. For information on the netCDF file format see: https://www.unidata.ucar.edu/software/netcdf/   Filenames follow the convention:   ```network-instrument_sitecode_species_version.nc```   For these files, the network is 'agage-air-archive', and the instrument is 'GCMS-Medusa-flask'. Below is an example of the archive structure showing only CFC-11 and CFC-12 data at seven sites:   ``` ├── README.md └── cfc-11       ├── agage-air-archive-GCMS-Medusa-flask_brw_cfc-11_20250212v1.nc       ├── agage-air-archive-GCMS-Medusa-flask_cgo_cfc-11_20250212v1.nc       ├── agage-air-archive-GCMS-Medusa-flask_cmo_cfc-11_20250212v1.nc       ├── agage-air-archive-GCMS-Medusa-flask_ljo_cfc-11_20250212v1.nc       ├── agage-air-archive-GCMS-Medusa-flask_nwr_cfc-11_20250212v1.nc       ├── agage-air-archive-GCMS-Medusa-flask_spo_cfc-11_20250212v1.nc       └── agage-air-archive-GCMS-Medusa-flask_thd_cfc-11_20250212v1.nc └─── cfc-12       ├── agage-air-archive-GCMS-Medusa-flask_brw_cfc-12_20250212v1.nc       ├── agage-air-archive-GCMS-Medusa-flask_cgo_cfc-12_20250212v1.nc       ├── agage-air-archive-GCMS-Medusa-flask_cmo_cfc-12_20250212v1.nc       ├── agage-air-archive-GCMS-Medusa-flask_ljo_cfc-12_20250212v1.nc       ├── agage-air-archive-GCMS-Medusa-flask_nwr_cfc-12_20250212v1.nc       ├── agage-air-archive-GCMS-Medusa-flask_spo_cfc-12_20250212v1.nc       └── agage-air-archive-GCMS-Medusa-flask_thd_cfc-12_20250212v1.nc   ``` Note on timestamps Many of the archive air tanks have been measured multiple times, particularly tanks that were used as primary or secondary calibration standards for the propagation of calibration scales across the AGAGE network or the re-analysis of the archives for new species. To preserve the individual measurement records, these files contain all measurements made of the archives, without any averaging. As a result, many files will have duplicate timestamps, corresponding to these multiple measurements of tanks. AGAGE Archive Data Availability Statement Before using these data in any way, first contact Jens Mühle ([email protected]) and Paul B. Krummel ([email protected]) (or, if not available, other appropriate AGAGE and CSIRO contacts). The availability of these data does not constitute publication of the data. AGAGE relies on the ethics and integrity of the user to ensure that the AGAGE scientists receive fair credit for their work. If these archive data or other AGAGE data are obtained for potential use in a publication or presentation, AGAGE should be informed at the outset of this work. If these or other AGAGE data are essential to your work, or if an important result or conclusion depends on these or other AGAGE data, co-authorship may be appropriate. This should be discussed at an early stage with AGAGE contacts given above. Manuscripts using these archive data or other AGAGE data should be sent to the AGAGE contacts for review before they are submitted for publication so we can ensure that the quality and limitations of the data are accurately represented. Every effort is made to produce the most accurate and precise measurements possible. However, we reserve the right to make corrections to the data based on recalibration of standard gases, updated filtering algorithm, additional archived air measurements, or for other reasons deemed scientifically justified. We are not responsible for results and conclusions based on use of these data without regard to this warning. Data Reciprocity Agreement Use of these data implies an agreement to reciprocate. Laboratories making similar measurements agree to make their own data available to the general public and to the scientific community in an equally complete and easily accessible form. Acknowledgements Publications using these archive data or other AGAGE data must include proper citations of this data set, the AGAGE network and its major funding agencies, as well as most relevant AGAGE publications. Please contact Jens Mühle ([email protected]) and Paul B. Krummel ([email protected]) (or, if not available, other appropriate AGAGE and CSIRO contacts) for detailed information and any updates.