Supplemental information for flask data provided from the Global Monitoring Division of the National Oceanic and Atmospheric Administrationís Earth System Research Laboratory (NOAA/ESRL/GMD) as a result of analysis on gas chromatography with mass spectrometry instrumentation.

Measurements of halocarbons and other trace gases from flasks by gas chromatography with mass spectrometry detection.

Principal Investigators:

Data Usage

Follow this link for the ESRL/GMD/HATS data use policy.

Key to NOAA GCMS Flask Data Files:

  • First column:

    Site where the flask sample was collected.
    Code legend for flask sampling locations:
    • South Pole (SPO, 90°S, 2837 m asl)
    • Palmer Station, Antarctica (PSA, 64.6°S, 64.0°W, 10 m asl)
    • Cape Grim, Australia (CGO, 40.682°S, 144.688°E, 164 m asl; inlet is 70 m agl)
    • American Samoa (SMO, 14.247°S, 170.564°W, 77 m asl)
    • Mauna Loa, USA (MLO, 19.5362°N, 155.5763°W, 3397 m asl)
    • Cape Kumukahi, USA (KUM, 19.516°N, 154.811°W, 3 m asl)
    • Niwot Ridge, USA (NWR, 40.1°N, 105.5°W, 3475 m asl)
    • Trinidad Head, USA (THD, 41.0°N, 124.1°W, 120 m asl)
    • Wisconsin, USA (LEF, 45.6°N, 90.27°W, 868 m asl; inlet is 396 m agl)
    • Harvard Forest, USA (HFM, 42.5°N, 72.2°W, 340 m asl; inlet is 29 m agl)
    • Mace Head, Ireland (MHD, 53.3°N, 9.9°W, 42 m asl)
    • Barrow, USA (BRW, 71.3°N, 156.6°W, 8 m asl)
    • Alert, Canada (ALT, 82.5°N, 62.3°W, 210 m asl)
    • Summit, Greenland (SUM, 72.6°N, 38.4°W, 3200 m asl)

    → Where asl = "above sea level" and asg = "above ground level"

  • Second and third columns:

    Sampling date and time expressed as a fraction of the year elapsed before the sample was collected, and, in the third column, expressed as yyyymmdd hhmmss.

    Note that 'SampleDate' includes the exact time of sampling (GMT) ONLY for data after November, 1994 ('SampleDate' for the oldest data has not been updated to include sample time; for example, a flask filled on 10 Feb 1994 at 1000 GMT would be indicated here as a decimal date corresponding to 10 Feb 1994 at 0000 GMT).

  • Fourth and fifth column:

    Wind direction and wind speed recorded at the time of sampling. Values of nd or -99 indicate magnitudes that were not recorded.

  • Sixth and seventh column:

    The dry air mole fraction (in picomol per mol or parts per trillion) determined for the sample and 1 standard deviation of the mean mole fraction derived for the two simultaneously filled flasks. Results are derived from the sampling and analysis of 2 stainless steel or glass flasks filled simultaneously.

Other notes:

Data are reported in this file only if the flask pairs had no statistically discernable difference at the 90-95% confidence level; if the standard deviation of the individual flasks within a pair is larger than the instrument precision determined by replicate injections, those results are not included here. Some additional culling of data is also based on relative magnitudes of flask differences within a pair.

Results for HFC-365mfc were published in Montzka et al. (2015) referenced to an incorrect calibration scale. Results referenced to the correct scale now appear in the posted file that includes measurement and derived emissions provided in that paper (JPhysChem2014 paper) and in web data files from NOAA HATS.

Compound listing:

Data available on ESRL/GMD/HATS website

Global surface mixing ratios, total tropospheric chlorine, bromine and fluorine

Known data issues:

We strive to provide the highest quality data possible for all periods. However, NOAA flask data obtained by the GCMS for some compounds analyzed during the 2008.5-2009.5 period are subject to some small biases owing to instrumental issues during that period. Data obtained for CH3CCl3 during that time period, for example, should not be used for deriving hydroxyl radical concentrations.

Furthermore, flask data for HCFC-142b shows some anomalously low values in recent years and specific seasons that are not yet flagged. Work is ongoing to discern the cause and apply the appropriate flags, but as of 2015, this is not yet completed.

For more information, see the articles in which initial portions of these data are published:

  • S. A. Montzka, J. H. Butler, R. C. Myers, T. M. Thompson, T. H. Swanson, A. D. Clarke, L. T. Lock, and J. W. Elkins, Decline in the tropospheric abundance of halogen from halocarbons: Implications for stratospheric ozone depletion, Science, 272, 1318-1322, 1996.
  • S. A. Montzka, J. H. Butler, J. W. Elkins, T. M. Thompson, A. D. Clarke, and L. T. Lock, Present and Future Trends in the Atmospheric Burden of Ozone-Depleting Halogens, Nature, 398, 690-694, 1999.
  • For brominated gases:

  • Montzka, S.A, J.H. Butler, B.D. Hall, J.W. Elkins, D.J. Mondeel, A decline in tropospheric organic bromine, Geophy. Res. Lett., 30(15), 1826, doi:10.1029/2003GL017745, 2003.
  • Butler, J.H., S.A. Montzka, A.D. Clarke, J.M. Lobert, J.W. Elkins, Growth and distribution of halons in the atmosphere, J. Geophys. Res., 103, 1503-1511, 1998.
  • For methyl chloroform:

  • Montzka, S.A., M. Krol, E. Dlugokencky, B. Hall, P. Jockel, J. Lelieveld, Small interannual variability of global atmospheric hydroxyl, Science, 331, 67-69, 2011.
  • Montzka, S.A., C.M. Spivakovsky, J.H. Butler, J.W. Elkins, L.T. Lock, and D.J. Mondeel, New observational constraints for atmospheric hydroxyl on global and hemispheric scales, Science, 288, 500-503, 2000.
  • For HCFCs and HFCs:

  • Montzka, S.A., B.D. Hall, J.W. Elkins, Accelerated increases observed for hydrochlorofluorocarbons since 2004 in the global atmosphere, Geophys. Res. Lett., 36, L03804, doi:10.1029/2008GL036475, 2009.
  • Montzka, S.A., R.C. Myers, J.H. Butler, and J.W. Elkins, Early trends in the global tropospheric abundance of hydrochlorofluorocarbon-141b and -142b, Geophys. Res. Lett., 21, 2483-2486, 1994.
  • Montzka, S.A., R.C. Myers, J.H. Butler, J.W. Elkins, and S.O. Cummings, Global tropospheric distribution and calibration scale of HCFC-22, Geophys Res. Lett., 20, 703-706, 1993.
  • Montzka, S.A., R.C. Myers, J.H. Butler, J.W. Elkins, L. Lock, A. Clarke, and A.H. Goldstein, Observations of HFC-134a in the remote troposphere, Geophys Res. Lett., 23, 169-172, 1996.
  • Montzka, S.A., M. McFarland, S.O. Andersen, B.R. Miller, D.W. Fahey, B.D. Hall, L. Hu, C. Siso, J.W. Elkins, Recent trends in global emissions of hydrochlorofluorocarbons and hydrofluorocarbonsóReflecting on the 2007 Adjustments to the Montreal Protocol, J. Phys. Chem. A, 119, 4439-4449, doi:10.1021/jp5097376, 2015.
  • For carbonyl sulfide:

  • Montzka, S.A., P. Calvert, B. Hall, J.W. Elkins, P. Tans, and C. Sweeney, On the global distribution, seasonality, and budget of atmospheric carbonyl sulfide (COS) and some similarities to CO2, J. Geophys. Res., 112, D09302, doi:10.1029/2006JD07665, 2007.
  • Montzka, S.A, M. Aydin, M. Battle, J.H. Butler, E.S. Saltzman, B.D. Hall, A.D. Clarke, D. Mondeel, J.W. Elkins, A 350-year atmospheric history for carbonyl sulfide inferred from Antarctic firn air and air trapped in ice, J. Geophys. Res., 109, D22302, doi:10.1029/2004JD004686, 2004.