----------------------------------------------------------------------------- Readme file to accompany AGAGE continuous tower data sets 2000-2009 v20100728 ----------------------------------------------------------------------------- TERMS AND CONDITIONS (Adapted from NOAA and NACP data policy) ----------------------------------------------------------------------------- CITATION INFORMATION 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 AGAGE continuous tower data sets should be cited as follows: (i) General reference for all species: instrumentation, calibration and measurements Prinn, R.G., R.F. Weiss, P.J. Fraser, P.G. Simmonds, D.M. Cunnold, F.N. Alyea, S. O'Doherty, P. Salameh, B.R. Miller, J. Huang, R.H.J. Wang, D.E. Hartley, C. Harth, L.P. Steele, G. Sturrock, P.M. Midgley, and A. McCulloch, A History of Chemically and Radiatively Important Gases in Air deduced from ALE/GAGE/AGAGE, J. Geophys. Res., 105, 17,751-17,792, 2000. (ii) Species from GCMD measurements CFC-11, CFC-12 -------------- Cunnold, D.M., R. F. Weiss, R. G. Prinn, D. E. Hartley, P. G. Simmonds, P.J. Fraser, B. R. Miller, F. N. Alyea, and L. Porter, GAGE/AGAGE measurements indicating reduction in global emissions of CCl3F and CCl2F2 in 1992-1994, J. Geophys. Res., 102, 1259-1269, 1997 CH3CCl3: ---------- (a) all stations: Prinn, R.G., J. Huang, R.F. Weiss, D.M. Cunnold, P.J. Fraser, P.G. Simmonds, A. McCulloch, C. Harth, S. Reimann, P. Salameh, S. O'Doherty, R.H.J. Wang, L. Porter, B.R. Miller, and P.B. Krummel, Evidence for variability of atmospheric hydroxyl radicals over the past quarter century, Geophys. Res. Lett., 32, L07809, 10.1029/2004GL022228, 2005. Prinn, R.G., J. Huang, R.F. Weiss, D.M. Cunnold, P.J. Fraser, P.G. Simmonds, A. McCulloch, C.Harth, P. Salameh, S. O'Doherty, R.H.J. Wang, L. Porter, and B.R. Miller, Evidence for significant variations of atmospheric hydroxyl radicals in the last two decades, Science, 292. 1882-1888, 2001 CCl4 ------- Simmonds, P.G., D. M. Cunnold, R.F. Weiss, R.G. Prinn, P.J. Fraser, A. McCulloch, F.N. Alyea, and S. O'Doherty, Global trends and emissions of CCl4 from in-situ background observations from July 1978 to June 1996, J. Geophys. Res., 103, 16017-16027, 1998. N2O ----- Prinn, R.G., D.M. Cunnold, R. Rasmussen, P.G. Simmonds, F.N. Alyea, A. Crawford, P.J. Fraser, and R. Rosen, Atmospheric emissions and trends of nitrous oxide deduced from ten years of ALE-GAGE data, J. Geophys. Res., 95, 18369-18385, 1990. CFC-113 --------- Fraser, P., D. Cunnold, F. Alyea, R. Weiss, R. Prinn, P. Simmonds, B. Miller, and R. Langenfelds, Lifetime and emission estimates of 1,1,2-trichlorotrifluorethane (CFC- 113) from daily global background observations June 1982- June 1994., J. Geophys. Res., 101, 12,585-12,599, 1996. CH4: ------ Cunnold, D.M., L.P. Steele, P.J. Fraser, P.G. Simmonds, R.G. Prinn, R.F. Weiss, L.W. Porter, R.L. Langenfelds, H.J. Wang, L. Emmons, X.X. Tie, and E.J. Dlugokencky, In situ measurements of atmospheric methane at GAGE/AGAGE sites during 1985-2000 and resulting source inferences. J. Geophys. Res., 107, D14, doi: 10.1029/2001JD001226, 2002. CHCl3: -------- O'Doherty, S., D. Cunnold, G.A. Sturrock, D. Ryall, R.G. Derwent, H.J. Wang, P. Simmonds, P.J. Fraser, R.F. Weiss, P. Salameh, B.R. Miller, and R.G. Prinn, In-situ chloroform measurements at AGAGE atmospheric research stations from 1994-1998, J. Geophys. Res., 106, 20,429-20,444, 2001. (iii) Species from GCMS measurements CH3Br, CH3Cl -------------- Simmonds, P.G., S. O'Doherty, R.G. Derwent, A.J. Manning, D.B. Ryall, P. Fraser, L. Porter, P. Krummel, R. Weiss, B. Miller, P. Salameh, D. Cunnold, R. Wang, and R. Prinn, AGAGE observations of methyl bromide and methyl chloride at the Mace Head, Ireland and Cape Grim, Tasmania, 1998-2001, J. Atmos. Chem., 47, 243-269, 2004. Cox. M.L. G.A. Sturrock, P.J. Fraser, S.T. Siems, P.B. Krummel, and S. O'Doherty, Regional sources of methyl chloride, chloroform and dichloromethane identified from AGAGE observations at Cape Grim, Tasmania, 1998-2000., J. Atmos. Chem., 45, 79-99, 2003. HFC-134a, HCFC-141b, -142b, -22 --------------------------------- O'Doherty, S., D.M. Cunnold, P.G. Simmonds, G. Sturrock, J. Huang, R.G. Prinn, L.W. Porter, P.J. Fraser, P.B. Krummel, B.R. Miller, P. Salameh, R.F. Weiss, R.H.J. Wang, A. McCulloch, S. Montzka, A. Manning, D. Ryall, and R.G. Derwent, Rapid growth of hydrofluorocarbon 134a and hydrochlorofluorocarbons 141b, 142b, and 22 from Advanced Global Atmospheric Gases Experiment (AGAGE) observations at Cape Grim, Tasmania, and Mace Head, Ireland, J. Geophys. Res., 109, D06310, doi: 10.1029/2003JD004277, 2004. Miller, B.R., J. Huang, R.F. Weiss, R.G. Prinn and P.J. Fraser, Atmospheric trend and lifetime of chlorodifluoromethane (HCFC-22) and the global tropospheric OH concentrations, J. Geophys. Res., 103, 13,237-13,248, 1998. see AGAGE web site "http://agage.eas.gatech.edu" for more references. 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. PROJECT PURPOSE AND BACKGROUND ------------------------------ Advanced Global Atmospheric Gases Experiment (AGAGE), and its predecessors (the Atmospheric Life Experiment, ALE, and the Global Atmospheric Gases Experiment, GAGE) have been measuring the composition of the global atmosphere continuously since 1978. The AGAGE is distinguished by its capability to measure over the globe at high frequency almost all of the important gases species in the Montreal Protocol (e.g. CFCs and HCFCs) to protect the ozone layer and almost all of the significant non-CO2 gases in the Kyoto Protocol (e.g. HFCs, methane, and nitrous oxide) to mitigate climate change. AGAGE is part of the powerful global observing system that is measuring halocarbons, including bromocarbons, in the Earth's atmosphere. The ALE/GAGE/AGAGE stations occupy coastal sites around the world chosen to provide accurate measurements of trace gases whose lifetimes are long compared to global atmospheric circulation times. The scientific objectives of the ALE/GAGE/AGAGE programs are several in number and of considerable importance in furthering our understanding of a number of important global chemical and climatic phenomena. They are: 1. To optimally determine from observations, the rate of emission and/or chemical destruction (i.e. lifetime) of the anthropogenic chemicals (e.g. chlorocarbons, chlorofluorocarbons (CFCs), and bromocarbons) that contribute most of the reactive chlorine and bromine released into the stratosphere and/or are strong infrared absorbers. 2. To accurately document the global distributions and temporal behavior of the biogenic/anthropogenic gases N2O, CH4, CO, H2, CH3Cl, CH3Br, CH2Cl2, and CHCl3. 3. To optimally determine the average concentrations and trends of OH radicals in the troposphere by determining the rates of destruction of atmospheric CH3CCl3 and other hydrohalocarbons from continuous measurements of their concentrations together with industrial estimates of their emissions. 4. To determine optimally, using high frequency trace gas data (and theoretical estimates of their rates of destruction), the magnitudes and distributions by region of the surface sources of these gases. 5. To provide an accurate data base on the rates of accumulation of trace gases over the globe which can be used to test the synoptic-, regional- and global-scale circulation predicted by three dimensional models and/or to determine characteristics of the sources of these gases near the stations. 6. To provide routine measurements of CH4, CO and H2, and estimates of OH levels that can be used to test primary oxidation pathways in the atmosphere. Principal Investigators of AGAGE are Ronald G. Prinn (MIT) and Ray F. Weiss (Scripps). GENERAL ------- All measurements included in the accompanying data files were taken by a GCMD and/or Medusa GCMS system between 2000 and and September 2009 at the stations located in Trinidad Head, California and Ragged Point, Barbados. Station information for the accompanying data sets: Trinidad Head (THD) (41deg 3min N; 124deg 12min W; 140 masl) Ragged Point (RPB) (13deg 10min N; 59deg 25min W; 42 masl). (1) chemical species measured by AGAGE GC-ECD/FID/MRD system are CFC-11, CFC-12, CH3CCl3, CCl4, N2O, CFC-113, CH4, CHCl3, CO, and H2. (2) chemical compounds measured by AGAGE GC-MS (ADS) system are HFC-134a, HCFC-22, HCFC-141b, HCFC-142b, CH3Cl, CH3Br, Halon-1211, Halon-1301, HFC-152a, CH2Cl2, CHClCCl3, and CCl2CCl2. (3) The Medusa GCMS system was installed at Trinidad Head in April 2005. Currently there are 23 compounds measured by Medusa GC-MS instruments available for public archive. Available compounds are following, CFC-113 HCFC-22, HCFC-141b, HCFC-142b HFC-125, HFC-134a, HFC-152a, HFC-365mfc, HFC-23 Halon-1211, Halon-1301 CH3Cl, CH2Cl2, CHCl3, CH3Br CH3CCl3, CHClCCl2, CCl2CCl2 SF6, SO2F2 PFC-14, PFC-116, PFC-218 (4) In general data through Sep. 2009 are included in this update (5) Please be aware that Medusa TCE (CHClCCl2), and PCE (CCl2CCl2) data have not been applied "blank correction". Those data are preliminary and will be updated later (after blank correction is applied). (6) In this update the CH3Br, HFC-23, PFC-14, PFC-116 and PFC-218 data, measured by AGAGE ADS-Medusa instrument, are included. (7) Measured compounds considered to be influenced by pollution condition are labeled by "P" in a flag column immediately following the species concentration column. Those without "P" flags are considered as background (un-polluted) values. (See DATA FLAGS section below). MEASUREMENT SCALES ------------------ 1. All AGAGE data (except N2O, CH4, CHCl3, CO and H2) have been calibrated to the Scripps Institution of Oceanography's SIO-2005 scale since May 2006. The factors (SIO-2005/SIO-1998) for measured species are following, Species factor (SIO-2005/SIO-1998) ======== ========================== CFC-11, 0.9945 CFC-12, 1.000 CH3CCl3, 0.9957 CCl4, 1.000 CFC-113, 1.0042 2. The N2O and CHCl3 are still in SIO-1998 scale. Please see Prinn et al., (2000) paper for detail description of SIO-1998 scale. 3. The CH4 data are originally in the CSIRO-94 scale (Steele et al., Baseline Atmospheric Program Australia 1994-95, Francey et al., eds., Bureau of Meteorology and CSIRO-DAR, Melbourne, pp. 107-110, 1996). In current update, the CSIRO CH4 standard is multiplied by 1.0119 to converted to the Tohoku University standard, which is developed by T. Nakazawa and co-workers at Tohoku University, Sendai, Japan, in collaboration with the Nippon Sanso company (Aoki et al., 1992). 4. Scales for species measured by Medusa are as follows, CFCs CFC-113 CCl2FCClF2 SIO-2005 HCFCs HCFC-22 CHClF2 SIO-2005 HCFC-141b CH3CCl2F SIO-2005 HCFC-142b CH3CClF2 SIO-2005 HFCs HFC-125 CHF2CF3 UB-98 HFC-134a CH2FCF3 SIO-2005 HFC-152a CH3CHF2 SIO-2005 HFC-365mfc CH3CF2CH2CF3 Empa-2003 Halons H-1211 CBrClF2 SIO-2005 H-1301 CBrF3 SIO-2005 Halomethanes methyl chloride CH3Cl SIO-2005 dichloromethane CH2Cl2 UB-98 chloroform CHCl3 SIO-1998 Chlorinated solvents methyl chloroform CH3CCl3 SIO-2005 trichloroethylene CHClCCl2 UB-98 perchloroethylene CCl2CCl2 NOAA-2003B Sulfur compounds sulfur hexafluoride SF6 SIO-2005 sulfuryl fluoride SO2F2 SIO-2007 VARIABLE NAMES -------------- YYYYMMDD : Year, month, and day of sampling. doy : absolute day of year UTC : Coordinated Universal Time, in seconds from midnight station : Three letter code, based on NOAA station ID system, identifying station where measurements were collected. latitude : Latitude, in degrees longitude : Longitude, in degrees altitude : Altitude, in meters CCl4_G : Carbon tetrachloride mixing ratio measured by GCMD, in ppt CCl4_G.flag : Carbon tetrachloride data flag (see DATA FLAGS section below) cfc11_G : Trichlorofluoromethane (CFC) mixing ratio measured by GCMD, in ppt cfc11_G.flag : Trichlorofluoromethane data flag (see DATA FLAGS section below) cfc113_G : 1,1,2-Trichloro-1,2,2-trifluoroethane (CFC) mixing ratio measured by GCMD, in ppt cfc113_G.flag : 1,1,2-Trichloro-1,2,2-trifluoroethane data flag (see DATA FLAGS section below) cfc113_M : 1,1,2-Trichloro-1,2,2-trifluoroethane (CFC) mixing ratio measured by Medusa, in ppt cfc113_M.flag : 1,1,2-Trichloro-1,2,2-trifluoroethane data flag (see DATA FLAGS section below) cfc12_G : Dichlorodifluoromethane (CFC) mixing ratio measured by GCMD, in ppt cfc12_G.flag : Dichlorodifluoromethane data flag (see DATA FLAGS section below) CHCl3_G : Chloroform mixing ratio measured by GCMD, in ppt CHCl3_G.flag : Chloroform data flag (see DATA FLAGS section below) CHCl3_M : Chloroform mixing ratio measured by Medusa, in ppt CHCl3_M.flag : Chloroform data flag (see DATA FLAGS section below) CH2Cl2_M : Dichloromethane mixing ratio measured by Medusa, in ppt CH2Cl2_M.flag : Dichloromethane data flag (see DATA FLAGS section below) CH3Br_M : Bromoform mixing ratio, measured by Medusa, in ppt CH3Br_M.flag : Bromoform data flag (see DATA FLAGS section below) CH3CCl3_G : Methyl chloroform mixing ratio measured by GCMD, in ppt CH3CCl3_G.flag : Methyl chloroform data flag (see DATA FLAGS section below) CH3CCl3_M : Methyl chloroform mixing ratio measured by Medusa, in ppt CH3CCl3_M.flag : Methyl chloroform data flag (see DATA FLAGS section below) CH3Cl_M : Methyl chloride mixing ratio measured by Medusa, in ppt CH3Cl_M.flag : Methyl chloride data flag (see DATA FLAGS section below) CH4_G : Methane mixing ratio measured by Medusa, in ppb CH4_G.flag : Methane data flag (see DATA FLAGS section below) H1211_M : Bromochlorodifluoromethane (Halon 1211) mixing ratio measured by Medusa, in ppt H1211_M.flag : Bromochlorodifluoromethane data flag (see DATA FLAGS section below) H1301_M : Bromotrifluoromethane (Halon 1301) mixing ratio measured by Medusa, in ppt H1301_M.flag : Bromotrifluoromethane data flag (see DATA FLAGS section below) hcfc141b_M : 1,1-Dichloro-1-fluoroethane mixing ratio measured by Medusa, in ppt hcfc141b_M.flag : 1,1-Dichloro-1-fluoroethane data flag (see DATA FLAGS section below) hcfc142b_M : 1-Chloro-1,1-difluoroethane mixing ratio measured by Medusa, in ppt hcfc142b_M.flag : 1-Chloro-1,1-difluoroethane data flag (see DATA FLAGS section below) hcfc22_M : Chlorodifluoromethane mixing ratio measured by Medusa, in ppt hcfc22_M.flag : Chlorodifluoromethane data flag (see DATA FLAGS section below) hfc23_M : Fluoroform mixing ratio, measured by Medusa, in ppt hfc23_M.flag : Fluoroform data flag (see DATA FLAGS section below) hfc125_M : Pentafluoroethane mixing ratio measured by Medusa, in ppt hfc125_M.flag : Pentafluoroethane data flag (see DATA FLAGS section below) hfc134a_M : 1,1,1,2-Tetrafluoroethane mixing ratio measured by Medusa, in ppt hfc134a_M.flag : 1,1,1,2-Tetrafluoroethane data flag (see DATA FLAGS section below) hfc152a_M : 1,1-Difluoroethane mixing ratio measured by Medusa, in ppt hfc152a_M.flag : 1,1-Difluoroethane data flag (see DATA FLAGS section below) hfc365_M : 1,1,1,3,3-pentafluorobutane mixing ratio measured by Medusa, in ppt hfc365_M.flag : 1,1,1,3,3-pentafluorobutane data flag (see DATA FLAGS section below) N2O_G : Nitrous oxide mixing ratio measured by GCMD, in ppb N2O_G.flag : Nitrous oxide data flag (see DATA FLAGS section below) PCE_M : Perchloroethylene mixing ratio measured by Medusa, in ppt PCE_M.flag : Perchloroethylene data flag (see DATA FLAGS section below) pfc14_M : Tetrafluoromethane mixing ratio measured by Medusa, in ppt pfc14_M.flag : Tetrafluoromethane data flag (see DATA FLAGS section below) pfc116_M : Hexafluoromethane mixing ratio measured by Medusa, in ppt pfc116_M.flag : Hexafluoromethane data flag (see DATA FLAGS section below) pfc218_M : Octafluoropropane mixing ratio measured by Medusa, in ppt pfc218_M.flag : Octafluoropropane data flag (see DATA FLAGS section below) SF6_M : Sulfur hexafluoride mixing ratio measured by Medusa, in ppt SF6_M.flag : Sulfur hexafluoride data flag (see DATA FLAGS section below) SO2F2_M : Sulfuryl Fluoride mixing ratio measured by Medusa, in ppt SO2F2_M.flag : Sulfuryl data flag (see DATA FLAGS section below) TCE_M : Trichloroethylene mixing ratio measured by Medusa, in ppt TCE_M.flag : Trichloroethylene data flag (see DATA FLAGS section below) MISSING VALUES -------------- For files in .RData format, missing values are represented by "NA". For files in .csv format, missing values are represented by "NaN" DATA FLAGS ---------- Most species are accompanied by a column titled "species.flag". 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 COMMENT flag. An alphanumeric other than a period (.) in the THIRD column provides additional information about the collection or analysis of the sample. In the AGAGE data sets, a "P" in this third column indicates samples considered to be influenced by a pollution. condition. Samples without "P" flags are considered as background.