--------------------------------------------------------- Readme file to accompany Scripps CO2 Flask data v20041001 --------------------------------------------------------- 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. CO2 data can be cited as: Keeling, C.D. and T.P. Whorf. 2004. Atmospheric CO2 concentrations derived from flask air samples at sites in the SIO network. 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, Tennessee, U.S.A. http://cdiac.ornl.gov/trends/co2/sio-keel.html 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. SCRIPPS CO2 FLASK PROJECT PURPOSE & DESCRIPTION ----------------------------------------------- The PIs for this project are: Charles D. Keeling, Scripps Institution of Oceanography, University of California-San Diego, deceased Timothy P. Whorf, Scripps Institution of Oceanography, University of California-San Diego, twhorf@ucsd.edu Questions about these data should be addressed to T. J. Blasing (blasingtj@ornl.gov). I. Introduction This study presents CO2 concentrations spanning latitudes 82 N to 90 S, although only North American data is included here. The five stations of interest are Barrow, AK (71.32, -156.6, 11 masl), Mauna Loa, HI (19.53, -155.58, 3397 masl), Cape Kumukahi, HI (19.52, -154.49, 3 masl), La Jolla Pier, CA (32.15, -117.05, 10 masl), and Alert, NWT, Canada (82.47, -62,5, 210 masl). The station codes for these sites are BRW, MLO, KUM, LJO, and ALT. Most of the data are based on replicated (collected at the same time and place) flask samples taken at intervals of approximately one week to one month and subsequently subjected to infrared analysis. The study uses 5-liter evacuated glass flasks, which are returned to Scripps Institution of Oceanography (SIO) for analysis. The periods of record begin as early as 1957, but all North American records extend through 2001 (the accompanying data sets encompass the period 2000-2001). Questionable data are flagged with asterisks; the user is accordingly advised to use caution in including them in analysis or in interpreting them without reference to the flag codes that provide the rationale for data rejections. These long-term records of atmospheric CO2 concentration complement the continuous records made by SIO, and also complement the long term flask records of the Climate Monitoring and Diagnostics Laboratory of the National Oceanic and Atmospheric Administration. All these data are useful for characterizing seasonal and geographical variations in atmospheric CO2 over several years, and for assessing results of global carbon models. Flask data provide information about ÒinstantaneousÓ departures from the hourly or multi-hourly averages derived from the continuous data, and at the same time serve as a quality check on those averages. Additionally, flask samples can be archived for future analyses as more refined measuring techniques become available. Annual averages and amplitudes of the annual cycle of atmospheric CO2 concentration both decrease from high northern latitudes to high southern latitudes. Peak annual CO2 concentrations occur in spring, around May in mid latitudes of the Northern Hemisphere. For more information and data updates, visit: http://cdiac.ornl.gov/trends/co2/sio-keel-flask/ For further documentation, visit: http://cdiac.ornl.gov/ftp/ndp001a/ndp001a.pdf II. Methods Parameter Method PI CO2 Nondispersive infrared C. Keeling, T. Whorf, SIO/UCSD gas analyzer manufactured by Applied Physics Corporation. VARIABLE NAMES -------------- YYYYMMDD : Year, month, and day of sampling doy : Absolute day of year UTC : Universal Coordinated Time, in seconds from midnight flask.ID : Canister identification number station : NOAA three-letter station code. Three-letter codes assigned for non-NOAA station LJO latitude : Latitude, in degrees longitude : Longitude, in degrees altitude : Altitude, in meters above sea level CO2_SCRIPPS : CO2 mixing ratio via IR gas analyzer, in ppmv jscale.CO2_SCRIPPS: Index scale, can be I or J. A scale, linearly related to the APC infrared analyzer response, expressed in units close to CO2 mole fraction in ppm. All data are initially recorded on the I index scale. A linear transformation converts the I index scale to the J index scale, established in 1959 on the basis of manometric calibrations. MISSING VALUES --------------- For files in .RData format, missing values are represented by "NA" For files in .csv format, missing values are represented by "NaN"