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

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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, third, and fourth 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 and the fourth column is GMT time of date as HH:MM.

  • Fifth and sixth columns:

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

  • Seventh and eighth columns:

    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.

  • Ninth column:

    Flagging. All mole fraction data have been filtered to require: a) two aliquots per flask with differences <= 0.2 ppt (95% confidence interval), and b) flask pair differences <= 0.2 ppt (95% confidence interval).

    All known analytical and/or sampling problem data have been omitted. Data which appear anomalously high or low, but for which we do not know of any analytical or sampling issues, have been given a '>' or '<' flag symbol, respectively, in an effort to produce our best guess as to the background values, which are denoted with flag '–'.

  • Tenth column:

    Instrument code. PR1 = GCMS PERSEUS instrument, M2 = GCMS M2 instrument.

Compound listing:

Data available on ESRL/GMD/HATS website

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