Consistency of cruise data of the CARINA database in the Atlantic sector of the Southern Ocean

13 pages, 9 figures, 1 table.-- M. Hoppema ... et al.

Initially a North Atlantic project, the CARINA carbon synthesis was extended to include the Southern Ocean. Carbon and relevant hydrographic and geochemical ancillary data from cruises all across the Arctic Mediterranean Seas, Atlantic and Southern Ocean were released to the public and merged into a new database as part of the CARINA synthesis effort. Of a total of 188 cruises, 37 cruises are part of the Southern Ocean, including 11 from the Atlantic sector. The variables from all Southern Ocean cruises, including dissolved inorganic carbon (TCO2), total alkalinity, oxygen, nitrate, phosphate and silicate, were examined for cruise-to-cruise consistency in one collective effort. Seawater pH and chlorofluorocarbons (CFCs) are also part of the database, but the pH quality control (QC) is described in another Earth System Science Data publication, while the complexity of the Southern Ocean physics and biogeochemistry prevented a proper QC analysis of the CFCs. The area-specific procedures of quality control, including crossover analysis between stations and inversion analysis of all crossover data (i.e. secondary QC), are briefly described here for the Atlantic sector of the Southern Ocean. Data from an existing, quality controlled database (GLODAP) were used as a reference for our computations – however, the reference data were included into the analysis without applying the recommended GLODAP adjustments so the corrections could be independently verified. The outcome of this effort is an internally consistent, high-quality carbon data set for all cruises, including the reference cruises. The suggested corrections by the inversion analysis were allowed to vary within a fixed envelope, thus accounting for natural variability. The percentage of cruises adjusted ranged from 31% (for nitrate) to 54% (for phosphate) depending on the variable.

This work has been done and funded as part of the EU project CARBOOCEAN (no. 511176; GOCE). Additional support from the International Ocean Carbon Coordination Project IOCCP (Maria Hood) and the hospitality of the Hanse Institute for Advanced Study (HWK Delmenhorst, Germany) was gratefully accepted. R. M. Key was supported by NOAA grants NA08OAR4320752 and NA08OAR4310820; X. Lin by NOAA grant NA08OAR4310820; A. Velo, F. F. Perez and A. F. R´ıos by grants: PGIDIT05OXIC40203PM Xunta de Galicia and CTM200627116E/MAR MEC; M. A´ lvarez by grant RYC-2006-001836; R. G. J. Bellerby by IPY project Bipolar Atlantic Thermohaline Circulation (BIAC, IPY Cluster #23) and Southern Ocean Biogeochemistry: Education and research (project no. 180328) from the Norwegian Research Council.

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