In situ deployment of sensors for at least two parameters characterizing the carbonate system

This document is MINKE’s Deliverable D9.11 (2025), “In situ deployment of sensors for at least two parameters characterizing the carbonate system”. It describes the organisation and participation in an inter laboratory comparison (ILC) of pH instruments at Marseille in November 2023. The aim of the ILC was to have constant, controllable tanks representing realistic conditions, giving participants from around Europe the chance to intercompare their instruments and be introduced to metrology concepts. The report presents the results and lessons learnt, with advice for future ILCs. The ILC was also a useful opportunity to discuss carbonate chemistry, to meet and discuss with representatives from industry and to look at the community needs for metrology - summaries of these discussions are presented here with recommendations for the future. This deliverable makes conclusions on the type of measurement methods required for ‘weather’ and ‘climate’ goals in the measurement of pH variability.