Inorganic carbon and total alkalinity at the Western Channel Observatory from the L4 site from 2008 to 2022

Dissolved inorganic carbon and total alkalinity measurements sampled from station L4, part of the Western Channel Observatory, and analysed at Plymouth Marine Laboratory, 2008 to 2022. These measurements, together with temperature and salinity (Fishwick, 2018), total phosphate and silicate (Woodward & Harris 2023), (all available on the WCO website https://www.westernchannelobservatory.org.uk/data/), are used to calculate additional carbonate system parameters (pH, pCO2, saturation states of calcite and aragonite, HCO3- and CO32-) using the programme CO2sys [Lewis & Wallace, 1998], with dissociation constants from Lueker et al. [2000] and for KHSO4 from Dickson [1990]. Standard deviations on the values were propagated through to the calculated parameters following Orr et al. [2018]. Measurements are made as part of NERC National Capability time-series monitoring at the Western Channel Observatory (WCO).