Earth System Science Data Discussions www.earth-syst-sci-data-discuss.net 1866-3591 2 1 2009 10.5194/essdd-2-421-2009 http://www.earth-syst-sci-data-discuss.net/2/421/2009/ http://www.earth-syst-sci-data-discuss.net/2/421/2009/essdd-2-421-2009.html http://www.earth-syst-sci-data-discuss.net/2/421/2009/essdd-2-421-2009.pdf 421 475 2009-10-13 CARINA data synthesis project: pH data scale unification and cruise adjustments A. Velo avelo@iim.csic.es F. F. Pérez X. Lin R. M. Key T. Tanhua M. de la Paz S. van Heuven S. Jutterström A. F. Ríos Instituto de Investigaciones Marinas, CSIC, Eduardo Cabello, 6, 36208 Vigo, Spain Atmospheric and Oceanic Sciences Program, Princeton University, Princeton, NJ, USA Leibniz-Institute für Meereswissenschaften, Marine Biogeochemie, Kiel, Germany Netherlands Institute for Sea Research, Texel, The Netherlands Institutionen för kemi, Göteborgs universitet, Göteborg, Sweden Data on carbon and carbon-relevant hydrographic and hydrochemical parameters from previously non-publicly available cruise data sets in the Artic Mediterranean Seas (AMS), Atlantic and Southern Ocean have been retrieved and merged to a new database: CARINA (CARbon IN the Atlantic). <br><br> These data have gone through rigorous quality control (QC) procedures to assure the highest possible quality and consistency. The data for most of the measured parameters in the CARINA database were objectively examined in order to quantify systematic differences in the reported values, i.e. secondary quality control. Systematic biases found in the data have been corrected in the data products, i.e. three merged data files with measured, calculated and interpolated data for each of the three CARINA regions; AMS, Atlantic and Southern Ocean. Out of a total of 188 cruise entries in the CARINA database, 59 reported pH measured values. <br><br> Here we present details of the secondary QC on pH for the CARINA database. Procedures of quality control, including crossover analysis between cruises and inversion analysis of all crossover data are briefly described. Adjustments were applied to the pH values for 21 of the cruises in the CARINA dataset. With these adjustments the CARINA database is consistent both internally as well as with GLODAP data, an oceanographic data set based on the World Hydrographic Program in the 1990s. Based on our analysis we estimate the internal accuracy of the CARINA pH data to be 0.005 pH units. 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