C-SCOPE: new approaches for marine carbon observations. Part 2: Ocean observation strategies

The German-Brazilian research project C-SCOPE aimed to take marine carbon observations to a new level by combining, perfecting and expanding existing and new observation networks. Here we present our joint findings, based on a three-year long, interdisciplinary collaboration between oceanographers, chemists, data managers, modelers, and social scientists. This abstract focuses on the natural science contribution. A parallel submission focuses on social science-based insights. Activities in C-SCOPE focused on the ocean's CO2 uptake capacity in three key regions: the (i) thermohaline circulation system in the North Atlantic, (ii) Amazon rainforest system in South America and (iii) Baltic Sea, all of which are of highest climatic and/or socio-economic relevance and therefore in need of knowledge-based management. 

As a prerequisite for knowledge-based management, the marine (carbon) science system must become fit-for-purpose across time and space with equitable access to knowledge production. As steps towards an ocean observation strategy, the following lessons can be learnt from our three key regions: 

(i) the pilot study on the synergistic combination of BGC-Argo with existing ship-of-opportunity lines (SOOP) of the SOCONET/ICOS programme in the subpolar North Atlantic highlighted the need for a refined calibration procedure of the float mounted pH sensors. The study also showed the potential of combining different observation strategies to improve our observational capacities for marine carbon dynamics. 

(ii) A newly established SOOP line in the coast of Brazil at the Amazonian region demonstrates the effectiveness of this observational approach to reach traditionally undersampled regions of the coastal ocean. We highlight the challenges setting up this technique and show first novel results at the Brazilian coast. To better understand the carbon sources and sinks in this coastal region, we complement these observations with model simulated carbon fluxes at the Amazon River plume.

(iii) BGC-Argo’s standard pH sensor is incompatible with Baltic Sea biogeochemical conditions. To enable synergistic BGC-Argo and SOCONET/ICOS observations, C-SCOPE implemented a pCO2 sensor instead on a commercially available profiling float. Its pilot deployments in the Baltic Sea were able to show the feasibility of linked BGC-Argo-based profiling pCO2 and SOOP-based surface pCO2 observations in practice in a regional context, serving as a role model for synergy between observation networks for marine carbon observations.