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Atmospheric CO2 from Flask Air Samples at Cape Kumukahi, Hawaii, U.S.A.

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

March 1979 - December 2001


Atmospheric CO2 samples were collected roughly twice per month until 1981, and at roughly weekly intervals thereafter. Samples are collected in 5-L evacuated glass 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 Cape Kumukahi, Hawaii, U.S.A.
Cape Kumukahi, Hawaii, U.S.A.
Island seashore
19°31' N, 154°49' W
3 m above MSL
Map of Hawaii


The average of unflagged data for the first full year of measurements (1980) was 338.9 ppmv; 2001 values averaged 371.8 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.