Atmospheric carbon dioxide measurements in the remote global troposphere, 1981-1984

Abstract

The carbon dioxide concentration has been measured in air samples collected approximately once per week at 22 globally distributed sites during 1981-84. All samples were analyzed on the same non-dispersive infrared analyzer apparatus at the NOAA/GMCC laboratory in Boulder. The measured concentrations are directly traceable to the WMO primary C02 standards. Samples which do not contain well-mixed, regionally representative air or which have been contaminated during or subsequent to sampling, have been identified. The selected data have been analyzed using an objective curve fitting method which enables improved estimation of uncertainties associated with derived parameters. The latitudinal distribution of annual mean CO2 concentration at the network sites shows significant interannual variability possibly related to the 1982-83 El Niño/Southern Oscillation event. No evidence was found for significant interannual variations or trends in the phase or amplitude of the seasonal cycle. Significant interannual and interstation variability in the CO2 growth rate was observed. A growth rate minimum during 1982 was followed by a growth rate maximum in 1983, in association with the intense 1982-83 ENS0 event. The mean global growth rate for 1981-84 was 1.22 ppm yr-1.