In the context of the EU AtlantOS Project, IOCCP started it's work towards defining quantifiable targets for the biogeochemical observing system. As with development of Essential Ocean Variables we hope for a wide community input over time. The first step of this effort is to focus on the Atlanic Ocean before expanding the process to other basins.

With ongoing advances in observing technology, and a set of Biogeochemical Essential Ocean Variables (EOVs) already in place, priorities for designing an optimum observing system for marine biogeochemistry are now shifting towards a system-wide definition of a set of accepted observing targets for biogeochemical phenomena and EOVs developed in a process driven by relevant scientific and societal requirements.

The goal of the workshop on "Setting Observing Targets for Biogeochemical Observing System in the Atlantic" was to respond to the challenge of setting observing targets while simultaneously taking into account the myriad of spatio-temporal scales of the distinct biogeochemical phenomena of interest and the complex array of corresponding observing elements.

The workshop, held on 29 November – 1 December 2016 at the Institute of Oceanology of the Polish Academy of Sciences (IO PAN) in Sopot, Poland, brought together 15 experts (and two remote participants) in biogeochemical observations and modelling from several countries around the Atlantic: Brazil, United States, Norway, Ireland, United Kingdom, Belgium, France, Germany and Poland. During three days of hard work the workshop participants managed to fulfil the following goals:

• Define what an observing target is in the context of the biogeochemistry observing system
• Decide on phenomena for which to set observing targets (based on the list of phenomena developed by AtlantOS WP1)
• Set observing targets for biogeochemical phenomena (described by relevant EOVs)

Comparing the targets developed during this workshop with the current observing capabilities will enable a comprehensive gap analysis aimed at providing recommendations for designing optimized and enhanced Atlantic Ocean observing system. The outcomes of the workshop will be published as AtlantOS deliverable and will be further socialized with the community for input and expansion to other basins.