This dataset comprises two time series derived from partial pressure of CO₂ (pCO₂) data recorded at 30-minute intervals by the ASTAN cardinal buoy, located 3.1 km offshore from Roscoff in the western English Channel (France). The original pCO₂ dataset was developed by Gac et al. (2020, DOI:10.3389/fmars.2020.00712). The version of this dataset used in Robache and Schmitt (2025, doi: 10.5194/egusphere-2025-972) is publicly available via Bozec et a [...]