Title: Carbon isotopes in the ocean: What are we learning from the WOCE/CLIVAR/GO-SHIP Programs?
Abstract: Carbon isotopic analyses of DIC, both stable and radio- carbon (DI 13 C and DI 14 C, respectively), have been made on a global scale since the GEOSECS era (1970’s). Intense sampling and mapping occurred during the initial World Ocean Circulation Experiment (WOCE) hydrographic surveys in the 1990’s and repeated occupations of select WOCE lines have occurred during the Climate and Ocean: Variability, Predictability and Change (CLIVAR) and Global Ocean Ship-Based Hydrographic Investigations Program (GO-SHIP) programs. To date, the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS) has analyzed and reported over 30,000 individual samples that are now available in the Global Ocean Data Analysis Project (GLODAP) database. Studies employing the carbon isotope data are beginning to show the import of these measurements as well as the importance of continuing these surveys in the future. Comparison of measurements made at similar locations decades apart requires that the measurement protocols be robust and reproducible. Evidence of the reliability of the measurements will be presented followed by some examples of what we are learning from the global surveys.