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 Organization

NO 2
Acronym NOAA
Name Earth System Research Laboratory, NOAA
Address 1 R/GMD1
Address 2 NOAA/ESRL
Address 3 325 Broadway Boulder, CO 80305-3337
Country/Territory United States of America
Website https://www.esrl.noaa.gov/gmd/index.html

 Contact(s)

Name Gabrielle Petron
Prefix
Email gabrielle.petron@noaa.gov
Organization No 2
Organization acronym NOAA
Organization name Earth System Research Laboratory, NOAA
Organization country/territory United States of America
Address 1
Address 2
Address 3
Country/territory United States of America
Tel 303 497-4890
Fax
Last updated date 2019-09-10


 Background observation
 UTC
 ppb
 9999-12-31 00:00:00 - 9999-12-31 23:59:59: NOAA 1996
 9999-12-31 00:00:00 - 9999-12-31 23:59:59: Unknown(Gas chromatography (RGD))
 3 weeks
 
 
 [Hourly]
 [Daily]
 [Monthly] Monthly means are produced for each site by first averaging all valid measurement results in the event file with a unique sample date and time. Values are then extracted at weekly intervals from a smooth curve (Thoning et al., 1989) fitted to the averaged data and these weekly values are averaged for each month to give the monthly means recorded in the files. Flagged data are excluded from the curve fitting process. Some sites are excluded from the monthly mean directory because sparse data or a short record does not allow a reasonable curve fit. Also, if there are 3 or more consecutive months without data, monthly means are not calculated for these months.
 NOAA GMD uses a 3-column quality control flag where each column is defined as follows:
column 1 REJECTION flag. An alphanumeric other than a period (.) in the FIRST column indicates a sample with obvious problems during collection or analysis. This measurement should not be interpreted.

column 2 SELECTION flag. An alphanumeric other than a period (.) in the SECOND column indicates a sample that is likely valid but does not meet selection criteria determined by the goals of a particular investigation.

column 3 COMMENT flag. An alphanumeric other than a period (.) in the THIRD column provides additional information about the collection or analysis of the sample.
WARNING: A "P" in the 3rd column of the QC flag indicates the measurement result is preliminary and has not yet been carefully examined by the PI. The "P" flag is removed once the quality of the measurement has been determined.

If both the first and second column contain a period (e.g., "..." and "..I"), the sample is RETAINED.
Since samples are collected in pairs, the pair difference is calculated, and samples with a pair difference greater than 15 ppb are flagged. Retained and rejected flasks are flagged as follows.

(NOTE: If either the first or second of these characters is not a period, the sample has been rejected.)
Flag Description
Retained ... good pair (D <= 15 ppb)
Rejected .X. Not representative of background conditions (> 3 sigma from a fitted curve), may include unidentified sampling/analysis problems.

.N. High/low mixing ratio thought to not represent background condiitons.

P.. Poor flask pair agreement (D > 15 ppb)

Z.. Poor aliquot agreement (D > 7.5 ppb)

*.. off scale result, broken flask or unacceptable analysis

W.. Wrong flask type for H2

S.. Sample was collected through the CO2 intake for the in situ analyzer

..I Flask is one of the pair used in an intercomparison with the cooperating agency

The retained values comprise the data set that we feel best represents the H2 distribution in the remote, well-mixed global troposphere. It is possible, and even likely, that some values flagged as non-background conditions are valid
measurements, but represent poorly mixed air parcels influenced by local anthropogenic sources or strong local biospheric sources or sinks. Users of these data should be aware that data selection is a difficult but necessary aspect of the analysis and interpretation of atmospheric trace gas data sets, and the specific data selection scheme used may be determined by the goals of a of a particular investigation.
 Operational/Reporting
 
1  Lang, P.M., L.P. Steele, R.C. Martin, and K.A. Masarie, Atmospheric methane data for the period 1983-1985 from the NOAA/GMCC global cooperative flask sampling network, NOAA Technical Memorandum ERL CMDL-1, 1990a.
2  Lang, P.M., L.P. Steele, and R.C. Martin, Atmospheric methane data for the period 1986-1988 from the NOAA/CMDL global cooperative flask sampling network, NOAA Technical Memorandum ERL CMDL-2, 1990b.
3  Novelli, P.C., K.A. Masarie, and P.M. Lang, Molecular hydrogen in the troposhere: Global distributions and budget, J. Geophys Res., 104, 30,427-30,444, 1999.
4  Thoning, K.W., P.P. Tans, and W.D. Komhyr, 1989, Atmospheric carbon dioxide at Mauna Loa Observatory 2. Analysis of the NOAA GMCC data, 1974-1985, J. Geophys. Res., 94, 8549-8565.