Delta 13C isotopic ratios: oceanic carbon cycle model analysis of global oceanic carbon, 2004 (U.S. JGOFS Synthesis & Modeling Phase project results)

<p>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 CO₂and 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 We propose to develop and use this large, as yet unpublished data set to make direct comparisons between observations and model predictions and to render our entire body of sea water data in a form usable by other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.</p>