Towards an Integrated Observing System for Ocean Carbon and Biogeochemistry at a Time of Change

Abstract

Ocean biogeochemical cycles are currently undergoing fundamental changes -largely as a consequence of the addition of greenhouse gases to the atmosphere. The oceans are getting warmer, and their pH and oxygen levels are decreasing. Further changes may arise as a consequence of the perturbation of the global nitrogen cycle, leading to higher inputs of fixed nitrogen to the ocean by rivers and enhanced deposition of nitrogen to the surface ocean. These biogeochemical changes plus the concomitant changes in ocean circulation will have profound effects on some of the ocean's key services, i.e. its capability to mitigate climate change by removing anthropogenic CO 2 from the atmosphere, and its provision of important ecosystem services such as food and biodiversity. Documenting, understanding, and predicting these biogeochemical changes require a concerted and sustained observational effort that includes both the continuation of well-tested approaches and the development and implementation of novel systems. Of particular importance for the first set of approaches are the sustaining and extension of (i) a surface ocean volunteer ocean ship-based observing system primarily focusing on the determination of the air-sea exchange of CO 2 and upper ocean changes in carbonate chemistry, of (ii) an interior ocean researchship based system focusing on large-scale interior changes of the ocean's biogeochemistry (carbon, oxygen, nutrients, etc), and of (iii) ship-based and moored time-series observations at key sites, including the coastal ocean. Of particular importance for the second set of approaches are (i) the accelerated improvement, development and implementation of new observational elements on the Argo (Array for Realtime Geostrophic Oceanography) array (especially oxygen, but also nutrient and bio-optical sensors), and (ii) the development, testing, and deployment of novel sensors for the ocean's carbon system. Concerted synthesis efforts involving also novel approaches for merging observations with biogeochemical models will ensure that these observational elements realize their synergistic potential.

Air-Sea Interactions of Natural Long-Lived Greenhouse Gases (CO2, N2O, CH4) in a Changing Climate

“…In addition the rigorous standardisation of data collection and quality control procedures will be essential. Such technical developments will require substantial and sustained funding Byrne et al 2010;Feely et al 2010;Gruber et al 2010;Monteiro et al 2010). Encouragingly, the marine CO 2 community is already making good progress towards coordinated data collection and synthesis.…”

“…Remotely controlled floats and other moving platforms, such as gliders, would provide additional process information; -The development of data storage, data reduction, data synthesis, data assimilation and visualisation techniques, as well as continuation, automation and expansion of ongoing data synthesis efforts; -The development of models that can be validated by data; Byrne et al 2010;Feely et al 2010;Gruber et al 2010;Monteiro et al 2010). …”

Estimates of Water-Column Nutrient Concentrations and Carbonate System Parameters in the Global Ocean: A Novel Approach Based on Neural Networks

“…Given this context of a rapidly changing ocean, it is crucial to reinforce the observation capability of biogeochemical variables and develop ways of measuring or estimating new ones (Claustre et al, 2010;Gruber et al, 2010b). This is required not only for monitoring ongoing changes, but also to gain a better understanding of key biogeochemical processes and for reducing uncertainties in budgets of major elements (e.g., carbon, oxygen, nitrogen, phosphorus, and silicium).…”

Towards an Integrated Observing System: In Situ Observations

“…Underway observations from commercial ships along fixed routes have become a cost-effective way to analyze surface water properties from the vessel's water intake(s), or to deploy XBT (expendable bathythermograph) probes (as well as surface drifters and Argo floats), to tow simple sampling systems, or to . The traditional quantities analyzed from continuously pumped surface water are temperature and salinity (thermosalinograph, TSG), however more complicated automated chemical analysis systems can now be installed in a similar way, most notably for pCO 2 [9]. The resulting global sampling network is impressive, as shown in the maps (Fig.…”