----------------------------------------------------------------- Readme file to accompany Stanley C. Tyler UCI flask data v20040101 ----------------------------------------------------------------- TERMS AND CONDITIONS (Adapted from NOAA and NACP data policy) ------------------------------------------------------------- Use of these data in any part implies an agreement on the part of the user that individuals and/or institutions responsible for contributing to data sets used must be specifically cited in addition to a general citation of the NACP greenhouse gas database. CO and CH4 data can be cited as: Tyler, S.C., Mixing Ratios of CO, CO2, CH4, and Isotope Ratios of Associated 13C, 18O, and 2H in Air Samples from Niwot Ridge, Colorado, and Montana de Oro, California, USA (January 2004), DOI: 10.3334/CDIAC/atg.db1022 NACP investigators will include an acknowledgement in each publication or presentation arising from participation in NACP. The wording shall be similar to the following: "This study was part of the North American Carbon Program." Data providers and funding agencies may request additional acknowledgements. Upon publication of results, investigators should send the NACP Office an electronic copy of the publication. USE OF DATA These data are made freely available to the public and the scientific community in the belief that their wide dissemination will lead to a greater understanding and new scientific insights. The availability of these data does not constitute publication of the data. We rely on the ethics and integrity of the user to assure that the source(s) receive fair credit for their work. If the data are obtained for potential use in a publication or presentation, the source(s) should be informed at the outset of the nature of this work. If the source's data are essential to the work, or if an important result or conclusion depends on their data, co-authorship may be appropriate. This should be discussed at an early stage in the work. Manuscripts using the source's data should be sent to the source(s) for review before they are submitted for publication so we can ensure that the quality and limitations of the data are accurately represented. RECIPROCITY AGREEMENT Use of these data implies an agreement to reciprocate. Laboratories making similar measurements agree to make their own data available to the general public and to the scientific community in an equally complete and easily accessible form. Modelers are encouraged to make available to the community, upon request, their own tools used in the interpretation of the source data, namely well documented model code, transport fields, and additional information necessary for other scientists to repeat the work and to run modified versions. Model availability includes collaborative support for new users of the models. TYLER UCI FLASK DATA PROJECT PURPOSE & DESCRIPTION -------------------------------------------------- The PI for this project is: Stanley C. Tyler, University of California Irvine Department of Earth System Science, styler@uci.edu I. Introduction This project records flask data from two North American sites, Niwot Ridge, CO (NWR) and Montana de Oro National Park (MDO). The sampling sites are at (40.05, -105.58) and (35, -121) respectively. Air samples have been collected from both sites since the mid 1990's at semi-monthly to monthly intervals in order to provide time series. Such time series can provide information about: (1) seasonal cycling of CO, CO2, and CH4 sources and sinks in background air, (2) trends in atmospheric concentrations of CO2 and CH4 and their stable carbon, oxygen, and hydrogen isotopes, (3) the distribution of the hydroxyl (OH) radical in the atmosphere, and (4) the role of the terrestrial biosphere as a source or sink of atmospheric CO2. The data presented here are discussed in detail by Tyler et al., (1999). Samples at Niwot Ridge were collected before noon in order to increase the likelihood of sampling when the prevailing wind was from the west, so as to represent well-mixed background air from over the western United States without interference from regional contamination. Samples from Montana de Oro were collected in late afternoon or early evening during periods when prevailing winds were from the west or northwest (i.e., from the Pacific Ocean). Air from Niwot Ridge was collected into passivated aluminum high-pressure cylinders using a RIX model SA-3 compressor; air from Montana de Oro was collected into electro-polished 32-liter stainless steel canisters using a portable battery- operated piston pump (Model 415CDC30/12B, Thomas Co., Sheboygan WI). Samples were then analyzed by gas chromatography at University of California-Irvine (see methods section for details). II. Methods Parameter Method PI a. CO Shimadzu Model 14A Gas S. Tyler, UCI Chromatograph (GC) with a Model RGD2 reduction gas analyzer detector (HgO) b. CH4 Hewlett Packard 5880A GC with flame ionization detector (FID) c. d13CH4 carbon isotopes were measured on a Finnigan MAT Model 252 Isotope-Ratio Mass Spectrometer (IRMS) d. d13CO Finnigan MAT IRMS e. dDCH4 The dD-CH4 analyses were performed using a cf-Gas- Chromatography/IRMS coupled to a custom-designed CH4 gas preconcentrator (Rice et al., 2001). A pyrolysis oven converts CH4 to H2 after its separation from the air stream and before its detection by the mass spectrometer. VARIABLE NAMES -------------- YYYYMMDD : Year, month, and day of sampling doy : Absolute day of year UTC : Universal Coordinated Time, in seconds from midnight station : NOAA 3-letter station code at Niwot Ridge (NWR). Montana de Oro is not a NOAA site and is given the code MDO. latitude : Latitude, in degrees longitude : Longitude, in degrees altitude : Altitude, in meters above sea level wind.m : Wind speed, in m/s wind.d : Wind direction, in degrees CH3D_UCI : Isotopic ratio of CH3D versus CH4 standard, in per mil SD.CH3D_UCI : Standard deviation of isotope ratio of CH3D versus CH4, in per mil CH4_UCI : CH4 mixing ratio via GC/FID, in ppbv SD.CH4_UCI : Standard deviation of CH4 mixing ratio, in ppbv CH4C13_UCI : Isotopic ratio of 13CH4 versus CH4 standard, in per mil SD.CH4C13_UCI : Standard deviation error of isotope ratio of 13C in CH4, in per mil CO_UCI : CO mixing ratio via GC/HgO, in ppbv SD.CO_UCI : Standard deviation of CO mixing ratio, in ppbv COC13_UCI : Isotopic ratio of 13CO versus CO standard, in per mil SD.COC13_UCI : Standard deviation of isotope ratio of 13CO versus CO standard, in per mil MISSING VALUES -------------- For files in .RData format, missing values are represented by "NA". For files in .csv format, missing values are represented by "NaN".