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.
Follow this link for the ESRL/GMD/HATS data use policy.
→ Where asl = "above sea level" and asg = "above ground level"
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.
Wind direction and wind speed recorded at the time of sampling. Values of nd or -99 indicate magnitudes that were not recorded.
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.
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 '–'.