Scripps O2 Program Data

This archive presents time-series measurements of atmospheric O2/N2 ratio and CO2 mole fraction from flask samples collected by the Scripps O2 program at twelve fixed land stations. Ten of these stations form an active network from nearly Pole to Pole along a Pacific transect. The earliest results in this network (from La Jolla) date from 1989. The remaining two stations are “legacy stations”, where flasks are no longer collected. Flasks are collected under atmospheric conditions designed to minimize the impact of any local process such as fuel burning that might impact atmospheric O2 or CO2. The sampling frequency is typically ~ 2 weeks. The O2/N2 ratio is reported as relative deviation from reference in δ units: δ = ((O2/N2)_samp /(O2/N2)_ref ) – 1, where (O2/N2)_samp is the O2/N2 mole ratio of the sample, (O2/N2)_ref is the ratio of a long-term reference. The quantity δ is multiplied by 10^6 and expressed in “per meg” units. Changes in CO2 are reported in “ppm” units, i.e. µmol CO2 per mole of H2O -free air. The Scripps O2 program has been directed throughout its history by Prof. Ralph Keeling. The program began while R. Keeling was a postdoc at the National Center for Atmospheric Research in Boulder, Colorado, and was moved to the Scripps Institution of Oceanography in 1993. The O2/N2 measurements are made on a custom interferometric analyzer, while the CO2 data use a Siemens non-dispersive infrared analyzer. Sampling, analysis, and calibration methods are described in Keeling et al (2007) and Keeling et al (1998). The Scripps O2 program is operationally independent from the Scripps CO2 program in using different flasks and analysis systems. The CO2 records of these two programs are therefore substantially independent, even though the flasks for both programs are collected at many of the same stations.