The CARINA data synthesis project: introduction and overview

Abstract

Abstract. The original goal of the CARINA (Carbon in Atlantic Ocean) data synthesis project was to create a merged calibrated data set from open ocean subsurface measurements by European scientists that would be generally useful for biogeochemical investigations in the North Atlantic and in particular, studies involving the carbon system. Over time the geographic extent expanded to include the entire Atlantic, the Arctic and the Southern Ocean and the international collaboration broadened significantly. In this paper we give a brief history of the project, a general overview of data included and an outline of the procedures used during the synthesis. The end result of this project was a set of 3 data products, one for each of the listed ocean regions. It is critical that anyone who uses any of the CARINA data products recognize that the data products are not simply concatenations of the originally measured values. Rather, the data have been through an extensive calibration procedure designed to remove measurement bias and bad data. Also a significant fraction of the individual values in the data products were derived either by direct calculation or some means of approximation. These data products were constructed for basin scale biogeochemical investigations and may be inappropriate for investigations involving small areal extent or similar detailed analyses. More information on specific parts of this project can be found in companion articles in this issue. In particular, Tanhua et al. (2009) and Tanhua (2009) describe the procedures and software used to remove measurement bias from the original data. The three data products and a significant volume of supporting information are available from the CARINA web site hosted by the Carbon Dioxide Information Analysis Center (CDIAC: http://cdiac.esd.ornl.gov/oceans/CARINA/Carina_inv.html). Anyone wanting to use the data is advised to get the highest version number of each data product. Incremental versions represent either corrections or additions. The web site documents specifics of the changes.

Nordic seas transit time distributions and anthropogenic CO2

“…This requires estimates of preformed alkalinity, Alk 0 , and these were obtained from salinity using the relationships specifically determined for the Nordic seas by Nondal et al [2009]. Preformed silicate and phosphate was set to 8 and 1 mmol kg −1 , respectively, typical concentrations of Nordic seas surface water in winter as determined from the CARINA data set [Key et al, 2010;Olafsson and Olsen, 2009]. The CO 2 system calculations were carried out using CO2sys [Lewis and Wallace, 1998] for Matlab [van Heuven et al, 2009] using the constants of Mehrbach et al [1973] refit by Dickson and Millero [1987].…”

“…Oxygen and CFC data were all obtained with a precision of ∼1% . The data from the three cruises are included in the CARINA data synthesis product [Key et al, 2010] and they have been found to be internally consistent [Falck and Olsen, 2010;Jeansson et al, 2010;Olsen et al, 2009;Olsen, 2009aOlsen, , 2009b, except the CFC-12 data obtained at the G.O. Sars cruise, which should be adjusted by a factor of 0.95 [Jeansson et al, 2010].…”

Nordic Seas dissolved oxygen data in CARINA

“…Calculated or interpolated values have been given the quality flag "0". A more comprehensive description of the complete CARINA database can be found in Key et al (2010), as well as in the other, more specialised, papers in this special issue, which includes the paper describing the oxygen data from the Atlantic Ocean region of CARINA (Stendardo et al, 2009). …”

Atlantic CFC data in CARINA

“…During the project, both primary and secondary quality control (QC) of the data has been performed. A comprehensive description of the complete CARINA data base can be found in Key et al (2009) as well as the other, more specialized, papers in this special issue. An overview of the Atlantic Ocean part of CARINA (CARINA-ATL) is given by Tanhua et al (2009).…”

“…The second part of CARINA is the merged data files. These are files with all the CARINA data and include: Interpolated values for nutrients, oxygen and salinity if those data are missing and if interpolation can be made according to criteria described in Key et al (2009); Calculated carbon parameters (e.g. if TCO 2 and alkalinity was measured, pH can be calculated).…”