12 years of continuous atmospheric O 2, CO 2 and APO data from Weybourne Atmospheric Observatory in the United Kingdom

We present a 12-year time series of continuous atmospheric measurements of O-2 and CO2 at the Weybourne Atmospheric Observatory in the United Kingdom. These measurements are combined into the term atmospheric potential oxygen (APO), a tracer that is invariant to terrestrial biosphere fluxes. The CO2, O-2 and APO datasets discussed are hourly averages between May 2010 and December 2021. We include details of our measurement system and calibration procedures, and describe the main long-term and seasonal features of the time series. The 2 min repeatability of the measurement system is approximately +/- 3 per meg for O-2 and approximately +/- 0.005 ppm for CO2. The time series shows average long-term trends of 2.40 ppm yr(-1) (2.38 to 2.42) for CO2, -24.0 per meg yr(-1) for O-2 (-24.3 to -23.8) and -11.4 per meg yr(-1) (-11.7 to -11.3) for APO, over the 12-year period. The average seasonal cycle peak-to-peak amplitudes are 16 ppm for CO2, 134 per meg for O-2 and 68 per meg for APO. The diurnal cycles of CO2 and O-2 vary considerably between seasons. The datasets are publicly available at https://doi.org/10.18160/Z0GF-MCWH (Adcock et al., 2023) and have many current and potential scientific applications in constraining carbon cycle processes, such as investigating air-sea exchange of CO2 and O-2 and top-down quantification of fossil fuel CO2.