Synthesis & Modeling Project
Charles D. Keeling
Oceanic carbon cycle model analysis of a new global set of oceanic carbon including extensive del-13C data and supporting measurements

NSF: OCE-9725955 01/98-12/99

PROJECT DESCRIPTION: We propose to use high precision and extensive isotopic ratio measurements of dissolved inorganic carbon (DIC) in sea water to verify aspects of global three-dimensional oceanic carbon cycle models related to the oceanic uptake of anthropogenic CO2 and to physical and biological processes.  The data for this purpose consist of measurements of the C13/C12 isotopic ratio in all the major ocean basins. Much of the data were obtained in expeditions of the World Ocean Circulation Experiment Hydrographic Program (WOCE/HP), but also include compatibly calibrated data from earlier programs,  including Transient Tracers in the Ocean (TTO) observations.  A majority of the measurements are of surface water, but there are also extensive deep water measurements and some vertical profiles.  The C13/C12 measurements are accompanied by DIC measurements of the same water samples, and usually by titration alkalinity (TA) measurements, except for the earliest expeditions.  Almost all measurements of C13/C12, DIC, and TA were made in duplicate on pairs of water samples so that erroneous data, arising from blunders in sampling or analysis, could be eliminated by requiring agreement between the measurements.  Using one or more three-dimensional models of the ocean carbon cycle, we will examine the data and relate it to important oceanic processes.  We propose to develop and use this large, as yet unpublished data set to make direct comparisons between observations and model predictions and to render our entire body of sea water data in a form usable by other modeling programs.


DATA: Results are available via the NCEI Ocean Carbon Data System (OCADS) Ocean Carbon and Acidification Data Portal; search for "Shore Based Carbon Analyses"

Nicolas Gruber, Charles D. Keeling, Robert Bacastow, Peter R. Guenther, Timothy J. Lueker, Martin Wahlen, Harro A. J. Meijer, Willem G. Mook, and Thomas F. Stocker. "Spatiotemporal patterns of carbon-13 in the global surface oceans and the oceanic Suess effect," Global Biogeochemical Cycles, vol. 13 (1999), p. 307.

Nicolas Gruber, Charles D. Keeling, and Thomas F. Stocker, "Carbon-13 constraints on the seasonal inorganic carbon budget at the BATS site in the northwestern Sargasso Sea," Deep-Sea Research Part I, vol. 45 (1998), p. 673.

Nicolas Gruber and Charles D. Keeling, "Seasonal carbon cycling in the Sargass Sea near Bermuda," Bulletin of the Scripps Institution of Oceanography, vol. 30 (1999), p. 1.

Timothy J. Lueker, Andrew G. Dickson, and Charles D. Keeling, "Ocean pCO2 calculated from dissolved inorganic carbon, alkalinity, and equations for K1 and K2: Validation based on laboratory measurements of CO2 in gas and seawater at equilibrium," Marine Chemistry, vol. 70 (2000), p. 105.

Nicolas Gruber, Charles D. Keeling, and Nicholas R. Bates, "Interannual variability in the North Atlantic Ocean carbon Sink," Science, vol. 298 (2002), p. 2374.

RELATED PROJECTS: - no related projects listed -


Charles D. Keeling
Scripps Institution of Oceanography
University of California, San Diego
9500 Gilman Drive
La Jolla, California 92093-0220
tel: (619) 534-4230
fax: (619) 534-8814