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Atmospheric CO2 from Flask Air Samples at Alert, Canada

graphics Graphics   data Data

C.D. Keeling and T.P. Whorf

Carbon Dioxide Research Group, Scripps Institution of Oceanography, University of California, La Jolla, California 92093-0444, U.S.A.

Period of Record



Atmospheric CO2 samples have been collected approximately weekly since 1985. Samples are collected in 5-L evacuated gas flasks, and then returned to the Scripps Institution of Oceanography (SIO) where CO2 concentrations have been determined using an Applied Physics Corporation (APC) nondispersive infrared gas analyzer. Further information on measurements, calibration procedures, and analysis is available in the references listed below.

Map showing location of Alert, Northwest Territories, Canada

Alert, Northwest Territories, Canada
Tundra (snow covered for almost
three quarters of the year)
82°28' N, 62°30' W
210 m above MSL


The average of unflagged data for the first year of measurements (1986) was 348.9 ppmv; 2001 values averaged 372.4 ppmv for an upward trend of 1.57 ppmv/year. Graphics here show the first and last year of data to display the change in mean over time and the annual amplitudes. Long term trend curves are better displayed using SIO's PDF monthly averaged data.


CITE 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.