12 years of continuous atmospheric O2, CO2 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 CO 2 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 CO 2 , 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 CO 2. The time series shows average long-term trends of 2.40 ppm yr -1 (2.38 to 2.42) for CO 2 , -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 CO 2 , 134 per meg for O 2 and 68 per meg for APO. The diurnal cycles of CO 2 and O 2 vary considerably between seasons. The datasets are publicly available at 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 CO 2 and O 2 and top-down quantification of fossil fuel CO 2. [ABSTRACT FROM AUTHOR]