FY 2011

A global sea surface carbon observing system: Assessment of changing sea surface CO₂ and air-sea CO₂ fluxes

Monteiro, P.M.S., U. Schuster, M. Hood, A. Lenton, N. Metzl, A. Olsen, K. Rogers, C. Sabine, T. Takahashi, B. Tilbrook, J. Yoder, R. Wanninkhof, and A.J. Watson

In Proceedings of the "OceanObs'09: Sustained Ocean Observations and Information for Society" Conference (Vol. 2), Venice, Italy, 21–25 September 2009, Hall, J., D.E. Harrison, and D. Stammer, Eds., ESA Publication WPP-306, doi: 10.5270/OceanObs09.cwp.64 (2010)

This paper identifies the important advances of the past decade that have delivered high precision pCO₂ observations from ships of opportunity (SOOP), robust decadal climatologies of air-sea CO₂ fluxes, and uniform data through coordinated quality control and inter comparisons activities, along with standardized instrumentation and procedures. The vision for the coming decade is to build on these successes to deliver an annual assessment and understanding of the regional and global trends in CO₂ exchanges between the ocean and the atmosphere. The core challenges are the maintenance and expansion of the sampling scales and the development of robust high precision in situ sensors.

Highest priorities for the next 10 years for a global sea surface carbon observing system are:

• to deliver seasonally unbiased annual assessments of the regional and global trends in ocean – atmosphere carbon fluxes. These should comprise monthly global flux maps that are used as constraints for atmospheric inversions in order to improve the assessment of the global carbon budget, including the terrestrial component. This will form an important link between the ocean CO₂ community and the global carbon budget assessment activities of the Global Carbon project (GCP) and its inputs to the periodic IPCC assessments. In order to achieve this, the following are necessary:
• to implement an effective and integrated multi-platform pCO₂ observing network that will reduce uncertainty in regional and global CO₂ flux estimates to ± 10 - 15% of the annual mean flux;
• to advance sensor and instrument development, allowing the density of global surface ocean carbon observing networks to be increased by deployment on additional key SOOP lines, moorings, Lagrangian platforms, gliders and profiling floats.
• to understand and resolve the biogeochemical and physical mechanisms driving surface carbon, natural and anthropogenic CO₂ air-sea flux variability and long term trend sand a link to ocean acidification by incorporating a robust set of ancillary observations;
• to strengthen the capabilities of coupled climate-carbon models to forecast changes in the ocean uptake of CO2 and the effectiveness of CO₂ emission mitigation strategies;
• to further strengthen, for instance through SOCAT, the international coordination of the carbon observations, data quality control, data archiving and the development of regular products for global and regional use.