In recent years, new technologies have been evolving with a whole new generation of sensors and instruments measuring pCO₂ in both the ocean surface and sub-surface entering the market.  These include «classical» equilibrator based systems with new CO₂ detectors to membrane based sensors that can be submerged.

The aim of this exercise is

• to compare the performance of instruments and sensors that are (or will be) used within the ICOS community over a range of temperatures and pCO₂ levels.
• to engage instrument suppliers and manufacturers to work together with the observational community to reach a high level of standardization in operating pCO₂ sensors and instruments.
• to give answers to the community of choosing the appropriate sensor for their application.

The ICOS Ocean Thematic Centre (OTC) invites all interested parties to participate in this exercise.

The aim is not only to compare different instrumentation, but also to improve the handling of instrumentation and of data, in order to achieve the best possible measurement quality being delivered. Below follows a tentative description of the inter-comparison, which will be amended through community input:

• Until summer 2020,
  • the OTC is gathering information about interested groups and what instrumentation they have expertise with and/or can provide for the exercise
  • the OTC is contacting manufacturers of instruments to raise their interest in participating in the exercise
• In the first half of 2020,
  • the OTC will identify  groups with expertise in specific instrumentation, users and manufacturers,  and bring them together
  • the groups are asked to develop “standard operation procedures” (SOP) – that describe the necessary steps that are needed for the specific instrument to achieve highest quality measurement. The SOP should be not longer than 2 pages and are meant to complement but not replace the user manual.
  • the OTC will distribute detailed information about the facility.
• The inter-comparison
  • will run for 2 weeks in summer 2021
  • can host max. 30 persons at a time
  • will have a daily data discussion to give the chance for adjustments to the deployed instruments
  •  will have the necessary infrastructure for the inter-comparison (server space, network, power supplies, pumps, temperature sensors, compressed gas standards, …)
• After the inter-comparison
  • the results will be published preferable in a data paper (e.g. ESSD) with actual instrumentation names