|Name||Earth System Research Laboratory, NOAA|
|Address 3||325 Broadway Boulder, CO 80305-3337|
|Country/Territory||United States of America|
|Organization name||Earth System Research Laboratory, NOAA|
|Organization country/territory||United States of America|
|Country/territory||United States of America|
|Last updated date||2019-09-10|
9999-12-31 00:00:00 - 9999-12-31 23:59:59: WMO CO X2014A
The air samples were collected on site in evacuated glass flasks or using a portable air sampling pump package. Two air samples were collected in series nearly simultaneously, constituting a pair (Lang et al., 1989 a,b). Quality of the air samples were evaluated by the difference between the two flasks. Until the 2017 data release, if they differed by < three ppb the samples were accepted, otherwise they are flagged and not used in further analysis (Novelli et al., 1998). Given the variability in CO mixing ratio and our measurement noise, we are in the process of revising the CO pair agreement to be 4 ppb. The 2018 data and some of the recent years use this new criteria. If one or both flasks have a sampling or analysis issue, the corresponding data is flagged with N or A in the first column and it should not be used.
The flask data will be reprocessed when the CO calibration scale is updated and uncertainty estimates will be provided.
[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 ESRL 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 INFORMATION 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 assessed.
|The instrument type is not provided as there are multiple analytical techniques used and users are welcome to contact the data PI for more information.|
|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||Gerbig, C., S. Schmitgen et al., An improved fast-response vacuum-UV resonance fluorescence CO instrument, J. Geophys. Res., 104, 1699-1704, 1999.|
|4||Novelli, P.C., J.E. Elkins, and L.P. Steele, The development and evaluation of a gravimetric reference scale for measurements of atmospheric carbon monoxide, J. Geophys. Res., 96, 13,109-13,121, 1991.|
|5||Novelli, P.C., L.P. Steele, and P.P. Tans, Mixing ratios of carbon monoxide in the troposphere, J. Geophys. Res., 97, 20,731-20,750, 1992.|
|6||Novelli, P.C., J.E. Collins, Jr, R.C. Myers, G.W. Sachse, and H.E. Scheel, Reevaluation of the NOAA/CMDL carbon monoxide reference scale and comparisons to CO reference gases at NASA-Langley and the Fraunhofer Institute, 99, 12,833- 12,839, 1994.|
|7||Novelli, P.C., K.A. Masarie, and P.M. Lang, Distributions and recent changes in carbon monoxide in the lower troposphere, J. Geophys. Res., 103, 19,1015- 19,033, 1998.|
|8||Novelli, P.C., K.A. Masarie, P.M. Lang, B.D. Hall, R.C. Myers, and J.W. Elkins, Re-analysis of tropospheric CO trends: Effects of the 1997-1998 wild fires, J. Geophys. Res., 108, D15 : 4464, doi:10.1029/2002JD003031, 2003.|
|9||G. Petron, A.M. Crotwell, E. Dlugokencky, J.W. Mund (2019), Atmospheric Carbon Monoxide Dry Air Mole Fractions from the NOAA ESRL Carbon Cycle Cooperative Global Air Sampling Network, 1988-2018, Version: 2019-08, https://doi.org/10.15138/33bv-s284|