{
  "title": "Reproduction of NOAA Analysis of Methane in Air, Table A1",
  "source": {
    "id": "2015_NOAA_CH4_Analysis",
    "title": "Analysis of Methane in Air",
    "institution": "NOAA ESRL Global Monitoring Division",
    "version": "1.2.1",
    "date": "2015-09-22",
    "url": "https://gml.noaa.gov/ccl/docs/TP_analysis_CH4_v1.2.1.pdf",
    "printed_page": 8,
    "pdf_page": 9,
    "sha256": "2d7f81ea8a9fbe196643f415509d58d78befd2d1c9e2ccaf008a29be037b16f3"
  },
  "accessed": "2026-10-19",
  "measurement_date": "2015-07-23",
  "selection": "All 41 records in Table A1: 20 unknown-sample injections and 21 bracketing reference injections. No filtering or invented inputs.",
  "table": {
    "file": "noaa-table-a1.csv",
    "type": "Transcription, not raw chromatograms",
    "sha256_lf": "0245856c991380749b86c2c91d78a79ee7fa8193c974464f96ee38f2b67952a9",
    "columns": {
      "date": "Date as printed",
      "time": "Time as printed, time zone unspecified",
      "port": "S = unknown sample, R = reference",
      "baseline_code": "BB copied unchanged, not interpreted or used in the calculation",
      "area": "Peak area in the instrument units of the original table, physical unit not specified",
      "reported_ratio": "NOAA response ratio, printed to nine decimal places",
      "reported_ch4_ppb": "NOAA calibrated dry-air mole fraction in ppb, input to the mean calculation"
    }
  },
  "calibration_scale": "WMO CH4 X2004A, as specified by the technical procedure",
  "calculation": "For each S row divide its area by the arithmetic mean of the immediately preceding and following R areas. Compare with published ratios. Compute the arithmetic mean and sample standard deviation (N-1 denominator) of the 20 published ppb values.",
  "scope": "Original chromatograms and numerical calibration coefficients are not provided in Table A1. The ratio-to-ppb conversion is not reproduced or inferred by fitting the rounded outputs.",
  "result": {
    "reference_mean_first": 8224596.5,
    "ratio_first": 0.9987438289525814,
    "sum_ppb": 37035.83,
    "mean_ppb": 1851.7915,
    "published_mean_ppb": 1851.79,
    "published_sample_sd_ppb": 0.74,
    "n": 20
  },
  "license": "Public Domain",
  "license_url": "https://gml.noaa.gov/about/disclaimer.html",
  "credit": "Data provided by NOAA Global Monitoring Laboratory, Boulder, Colorado, USA. Transcription, calculation and figure by Klimatologie.eu."
}