Antarctic ice core carbon monoxide records and composite spline 1821-1995 CE (Strawson et al., 2024)

Carbon monoxide mixing ratio of air trapped in ice core bubbles. Datasets from three Antarctic ice cores are presented: Jurassic, Bryan Coast and Dyer Plateau. These datasets contain a quasi-annual signal thought to result from the in situ production of carbon monoxide in ice. The composite spline should be used as a reference for the composition of past atmosphere. Ice cores were drilled by the British Antarctic Survey in 2011/12 (Jurassic and Bryan Coast) and Dyer Plateau in 1989. Data were generated via Continuous Flow Analysis (CFA) of 3.4 x 3.4 cm stick of ice core using an Optical Feedback Cavity Enhanced Spectroscopy (OF-CEAS) optical spectrometer across three analytical campaigns between 11/2021 and 01/2023. Data are 10 second averages from an original acquisition rate of 4 Hz. Data are corrected for minor blank and solubility effects and reported on the NOAA WMOX-2014 scale. The composite spline is the average of the 5th percentile records from the three cores. Uncertainty is given as 2 sigma (units of parts per billion (ppb)) and includes uncertainty on blank quantification and long-term reproducibility. Uncertainty on the composite spline is given as 2 sigma (ppb).