CMDL Hourly Average Surface Carbon Dioxide is historical data set DSI-3273, archived at the National Climatic Data Center (NCDC). Data were provided by the Climate Monitoring and Diagnostics Laboratory (CMDL), which is currently a part of the Office of Oceanic and Atmospheric Research (OAR) of the US National Oceanic and Atmospheric Administration (NOAA). The four observatories that provided data ... were maintained and operated by CMDL in locations where pollution and anthropogenic influences are frequently non-existent. The stations and periods of record were: Point Barrow, Alaska, USA Jul 1973-Dec 1992 Mauna Loa Observatory, Hawaii, USA May 1974-Dec 1992 Cape Matutula, American Samoa Jan 1976-Dec 1992 Amundsen-Scott (South Pole), Antarctica Mar 1975-Dec 1992 Station identifier, hourly average mixing ratio in parts per million (ppm), and date and time of observation were the major parameters of this data set. This historical data set is archived at NCDC in an element type format that is typical of the NCDC DS-32xx family of data sets. CMDL uses a distinctly different format for its own archival of this data. This data set is supplemented by DSI-3274, Meteorological Data from Four NOAA/OAR/CMDL Observatories.