Comment on essd-2023-129

Abstract

<strong class="journal-contentHeaderColor">Abstract.</strong> We present analyses of a 12-year time series of continuous atmospheric measurements of O₂ 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 conservative with respect to terrestrial biosphere processes. The CO₂, O₂ 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-minute repeatability of the measurement system is approximately &plusmn;3 per meg for O₂ and approximately &plusmn;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 O₂ (-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 O₂, and 68 per meg for APO. The diurnal cycles of CO₂ and O₂ vary considerably between seasons. The datasets are publicly available at <a href="https://doi.org/10.18160/Z0GF-MCWH" target="_blank" rel="noopener">https://doi.org/10.18160/Z0GF-MCWH</a> (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 O₂, and top-down quantification of fossil fuel CO₂.