--------------------------------------------------------------------------------------- Readme file to accompany Irvine Latitude Network flask data 2000-2008 version v20100921 --------------------------------------------------------------------------------------- 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. The Irvine Latitude Network data should be cited as follows: 1) D. Blake. 2005. Methane, Nonmethane Hydrocarbons, Alkyl Nitrates, and Chlorinated Carbon Compounds including 3 Chlorofluorocarbons (CFC-11, CFC-12, and CFC-113) in Whole-air Samples. In Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge Tenn., U.S.A. 2) Donald R. Blake Professor of Chemistry Department of Chemistry 570 Rowland Hall University of California, Irvine Irvine, CA 92697-2025 phone 949-824-4195 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. IRVINE LATITUDE NETWORK PROJECT PURPOSE & DESCRIPTION ----------------------------------------------------- **The attached data set spans the years 2000-2008. Note that the data from 2005-2008, while calibrated, has not been manually QCd for outliers.** The PIs for the project are: Donald R. Blake, UC Irvine, drblake@uci.edu These data were made possible by a continuing grant from NASA. I. Introduction The Irvine Latitude Network investigates the presence of methane, other hydrocarbons, alkyl nitrates, and chlorinated carbon compounds throughout the world. The network has an approximate latitudinal range of ~ -47 to 71 degrees, spanning 45 sampling locations. The network takes roughly 80 samples per season over three-week periods in March, June, September, and December. Whole-air samples are collected in conditioned, evacuated, 2-L stainless steel canisters; each canister is filled to ambient pressure over a period of about 1 minute (approximately 20 seconds to 2 minutes). These canisters are returned to the University of California at Irvine for chromatographic analysis. Analysis for methane includes gas chromatography with flame ionization, as discussed in Simpson, et al(1). Methane concentrations are reported for dry air, and are made relative to a primary standard purchased from the Matheson Gas Company in 1977 and to a National Bureau of Standards standard purchased in August 1982. Analytical precision is better than 2 parts per billion by volume. For additional details for methane measurements, and some discussion about methane trends, see Simpson, et al(1). Analyses for the various other gases is discussed in Colman, et al.(2). Samples were cooled to allow the more volatile components (e.g., argon, nitrogen, and oxygen) to be pumped away; the less volatile components were then revolatilized by immersing the sample loop in hot (80°C) water and subsequently flushed into a helium carrier flow. After chromatographic analysis, air from each sample was subjected to electron-capture analysis to distinguish between organic nitrates and halocarbons, flame ionization which is sensitive to hydrocarbons, and mass spectroscopy for unambiguous compound identification and selected ion monitoring. Signal from electron-capture and flame-ionization detectors was routed to an integrator which produced hard copies of the analog responses, and signals from all systems were routed to computers for further analysis. Each resulting chromatogram was manually modified, and each peak was individually checked, to assure that the large range of compound abundances and potential coelutors did not adversely affect quantification. Multiple standards were employed; working standards were run every 2 hours and calibrated standards were run twice daily. Standard gases used are discussed in Colman, et al(2). For the compounds included in this data set, the precision varies by compound class, and often by compound within a class. The precision of individual NMHCs increases with increasing carbon number, ranging from 0.5% (ethane) to 1% (i-butane). The precision of alkyl nitrates is 1% for ethyl nitrate and 2% for methyl and propyl nitrates. The halocarbon precision also varies by compound, ranging from 0.7% for CFC-12 to 1.2% for C2Cl4. For the compounds listed here the measurement accuracy is 5% for the NMHCs, 2-5% for halocarbons, and 10% for alkyl nitrates. The LOD is 3 pptv for NMHCs, 0.05-10 pptv for halocarbons, and 0.02 pptv for alkyl nitrates. For specific details on measurements of each gas, see Colman, et al(2). Papers cited: (1) Simpson, I.J., D.R.Blake, S.F.Rowland, T.Chen. Implications of the recent fluctuations in the growth rate of tropospheric methane, Geo. Res. Letters, Vol 29, No.10, doi:10.1029/2001GL014521, 2002. (2) Colman J.J., A.L.Swanson , S.Meinardi, B.C.Sive, D.R.Blake, F.S.Rowland. Description of the Analysis of a Wide Range of Volatile Organic Compounds in Whole Air Samples Collected during PEM- Tropics A and B, Anal. Chem. doi:10.1021/ac010027g For more information on the Irvine Latitude Network, visit: http://cdiac.ornl.gov/trends/otheratg/blake/blake.html For data updates, also visit CDIAC at: http://cdiac.ornl.gov/trends/otheratg/blake/data.html II. Methods Parameter Method PIs a. i.butane Gas chromatography D. Blake, UC Irvine with flame ionization detection (GC/FID) b. n.butane GC/FID c. CCl4 Gas chromatography with electron capture detector (GC/ECD) d. C2Cl4 GC/ECD e. cfc11 GC/ECD f. cfc113 GC/ECD g. cfc12 GC/ECD h. CHCl3 GC/ECD i. CH3CCl3 GC/ECD j. CH3ONO2 GC/ECD k. CH4 GC/FID l. ethane GC/FID m. ethyne GC/FID n. EtONO2 GC/ECD o. H1211 GC/ECD p. propane GC/FID q. i.PrONO2 GC/ECD VARIABLE NAMES -------------- YYYYMMDD : Year, month, and day of sampling doy : Absolute day of year flask.ID : Canister identification number location.comment: Description/comment of location latitude : Latitude, in degrees longitude : Longitude, in degrees i.butane_UCI : iso-butane mixing ratio, in pptv n.butane_UCI : butane mixing ratio, in pptv CCl4_UCI : carbon tetrachloride mixing ratio, in pptv C2Cl4_UCI : Tetrachloroethene mixing ratio, in pptv cfc11_UCI : Trichlorofluoromethane (CFC-11) mixing ratio, in pptv cfc113_UCI : 1,1,2-Trichloro-1,2,2-trifluoroethane (CFC-113) mixing ratio, in pptv cfc12_UCI : Dichlorodifluoromethane (CFC-12) mixing ratio, in pptv CHCl3_UCI : Chloroform mixing ratio, in pptv CH3CCl3_UCI : Methyl chloroform mixing ratio, in pptv CH3ONO2_UCI : Methyl nitrate mixing ratio, in pptv CH4_UCI : methane mixing ratio, in ppbv ethane_UCI : Ethane mixing ratio, in pptv ethyne_UCI : Ethyne mixing ratio, in pptv EtONO2_UCI : Ethyl nitrate mixing ratio, in pptv H1211_UCI : Bromochlorodifluoromethane (H-1211) mixing ratio, in pptv propane_UCI : Propane mixing ratio, in pptv i.PrONO2_UCI : isopropylnitrate mixing ratio, in pptv MISSING VALUES --------------- For files in .RData format, missing values are represented by "NA". For files in .csv format, missing values are represented by "NaN"