The following is a documents of NOAA/CMDL continuous in-situ CO2 data (The README file located in the co2/in-situ directory : accessible via ftp.cmdl.noaa.gov) which explains the flags assigned in the hourly files. ----------------------------------------------------------------------- *************************************************************** CONTINUOUS IN-SITU CO2 DATA FILES 30 Sep 1993 National Oceanic and Atmospheric Administration Climate Monitoring and Diagnostics Laboratory Carbon Cycle Group ************************************************************ These directories contain atmospheric CO2 mixing ratios from the 4 NOAA/CMDL obervatories, brw - Barrow, Alaska, mlo - Mauna Loa, Hawaii, smo - American Samoa, spo - South Pole Observatory. Correspondence concerning this data should be directed to: Dr. Pieter Tans Group Chief, Carbon Cycle Group NOAA/CMDL Mail Code R/E/CG1 Boulder, CO 80303 or Kirk Thoning NOAA/CMDL R/E/CG1 Boulder, CO 80303 or by electronic mail at ptans@cmdl.noaa.gov or kthoning@cmdl.noaa.gov ****************** NOTICE ************************************* When using the CO2 in-situ data in a publication or pre- sentation, you should acknowledge the National Oceanic and Atmospheric Administration (NOAA), Climate Monitoring and Diagnostics Laboratory (CMDL), Carbon Cycle Group. The principal investigators would appreciate being notified of any studies involving the data. We would also like to receive preprints of publications to insure that the quality and limitations of the NOAA/CMDL data are accurately represented. Feedback from users may also help us to improve the quality of the data. Comments regarding the README files and the data files are encouraged. Please send comments to the e-mail address given above. ************************************************************* !!!!!! WARNING !!!!!! Every effort is made to produce the most accurate and precise measurements possible. However, due to the measurement methods used, we reserve the right to make corrections to the data based on recalibration of reference gases and instrumentation. This is especially true for the following time periods, when relatively large corrections are likely: Samoa - September 1, 1991 to present South Pole - January 1, 1991 to present. Also read the 'Update_notes' file for information regarding problems and changes to the data sets. We are not responsible for results and conclusions based on use of this data without regard to this warning. ************************************************************* ------------------------------------------------------------------------------- Site information Site Elevation Code Site Country Lat Long (meters) _______________________________________________________________________________ BRW Point Barrow, Alaska U.S. 71 19'N 156 36'W 11 MLO Mauna Loa, Hawaii U.S. 19 32'N 155 35'W 3397 SMO American Samoa U.S. Territory 14 15'S 170 34'W 30 SPO Amundsen Scott (South Pole) Antarctica 89 59'S 24 48'W 2810 ------------------------------------------------------------------------------- Compressed tar files: In addition to the text files found in each of the directories, there are 4 compressed tar files which contain all the files in the corresponding directory, e.g. brw.in-situ.tar.Z contains all the files in the directory 'brw'. If you want to transfer all the files in a directory, it is much more efficient to take the tar file instead. To transfer these files do the following steps from the ftp prompt: 1. ftp> binary ! set transfer mode to binary 2. ftp> get brw.in-situ.tar.Z ! transfer the file 3. ftp> bye ! leave ftp 4. $ uncompress brw.in-situ.tar.Z ! uncompress your local copy 5. $ tar xvf brw.in-situ.tar ! unpack the file This will create a directory called 'brw' and place each of the files in this directory. Repeat the steps for each tar file. !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!! As of 04 October 1996, the Mauna Loa data files have a !!!! different format from the other sites. !!!! This will be fixed in the next couple of months. !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ------------------------------------------------------------ Hourly average data files: (brw, smo, spo only) Hourly average files are text files grouped by year, with one line of data for each hour of the year. The naming convention used for these files is "staxx" where 'sta' is the three letter code designating the station, and xx is the year. Valid station codes are: brw - Barrow, Alaska Observatory smo - American Samoa Observatory spo - South Pole Observatory For example , 'mlo1989' contains hourly averaged data from Mauna Loa for the year 1989. The format for each line is: xxx yyyy mm dd hh ddd.dd aa where: xxx is the station code, yy is the year, mm is the month, dd is the day, hh is the hour, ddd.dd is the CO2 mixing ratio in ppm, aa is a two letter code designating the selection applied to the data. Missing data will have a value of -999.99 for the mixing ratio. Times are specified in Greenwich Mean Time. Hours are specified as the beginning of the hour, for example, hour 5 corresponds to 5 AM to 6 AM GMT. The selection process is done to distinguish "background" mixing ratios, that is, the values that we believe are not contaminated by local sources or sinks of CO2. The selection process depends on the station (see references). There are a large number of possible codes, but the most common codes are: . - No code applied. Data is considered 'background'. C - Weekly calibration of reference gases, no data available I - Instrument malfunction, no data available V - Large variability of CO2 mixing ratio within one hour D - Hour-to-hour difference in mixing ratio > 0.25 ppm A - Automatic selection based on residuals from a spline curve DN - Rejected, diurnal variation (upslope) in CO2 (Mauna Loa only) NC - No analog chart record available, but data considered "background' Other codes may be used, but the main point is that missing data will have a value of -999.99 for the hour, and "background" values will be designated by a lack of a code or with a 'NC' code. See also the 'Update_notes' file for information regarding other codes. ---------------------------------------------------------------- Daily average files: The daily average files are grouped one file per year. The naming convention is "xxxdayyyyy" where sta is the station code and yyyy is the year. There is one line for each day of the year. The format for the lines is xxx yyyy mm dd ddd.dd dd.dd nn where: xxx - station code, yyyy - year, mm - month, dd - day, ddd.dd - daily average CO2 mixing ratio in ppm, dd.dd - standard deviation of hourly averages about daily average, nn - number of hourly averages used to calculate the daily average. Missing data has a value of -999.99 for the mixing ratio, -9.99 for the standard deviation, and 0 for the number of hours. The daily averages are based on only those hourly averages deemed to be "background" values. ---------------------------------------------------------------- Monthly average files: The monthly average files are grouped on file per station containing all monthly values for the record of measurement for that station. The file names are "xxxmm" where xxx is that station code. The format of the lines is xxx yyyy mm ddd.dd dd.dd nn where: xxx - station code, yyyy - year, mm - month, ddd.dd - monthly average CO2 mixing ratio. dd.dd - Standard deviation of daily averages about monthly average. nn - Number of daily averages used to calculate monthly average. Missing data has -999.99 for the mixing ratio. Monthly averages are computed from the daily averages. Missing daily averages are skipped. ---------------------------------------------------------------- References: Peterson, J.T., W.D. Komhyr, L.S. Waterman, R.H. Gammon, K.W. Thoning, and T.J. Conway, Atmospheric CO2 variations at Barrow, Alaska, 1973-1982, J. Atmos. Chem., 4, 491-510, 1986. Herbert, G.A., E.R. Green, J.M. Harris, G.L. Koenig, S.J. Roughton, and K.W. Thaut, Control and monitoring instrumentation for the continuous measurement of atmospheric CO2 and meteorological variables, J. Atmos. Oceanic Technol., 3, 414-421, 1986. Gillette, D.A., W.D. Komhyr, L.S. Waterman, L.P. Steele, and R.H. Gammon, The NOAA/GMCC continuous CO2 record at the South Pole, 1975-1982, J. Geophys. Res., 92, 4231-4240, 1987. Halter, B.C., Harris, J.M., and Conway, T.J., Component signals in the record of atmospheric carbon dioxide concentation at American Samoa, J. Geophys. Res., 93, 15914-15918, 1988. Komhyr, W.D., T.B. Harris, L.S. Waterman, J.F.S. Chin, and K.W. Thoning, Atmospheric carbon dioxide at Mauna Loa Observatory: 1. NOAA Global Monitoring for Climatic Change measurements with a nondispersive infrared analyzer, 1974-1985, J. Geophys. Res., 94, 8533-8547, 1989. Thoning, K.W., P.P. Tans, and W.D. Komhyr, Atmospheric carbon dioxide at Mauna Loa Observatory, 2. Analysis of the NOAA/GMCC data, 1974-1985., J. Geophys. Res. ,94, 8549-8565, 1989. Thoning, K.W. Selection of NOAA/GMCC CO2 data from Mauna Loa Observatory, In The Statistical Treatment of CO2 Data Records, NOAA Tech. Mem. (ERL-ARL-173), Environ. Res. Lab., 131 pp., 1989 Waterman, L.S., D. W. Nelson, W.D. Komhyr, T.B. Harris, and K.W. Thoning, Atmospheric carbon dioxide measurements at Cape Matatula, American Samoa, 1976-1984., J. Geophys. Res. , 94, 14817-14829, 1989.