A synthesis of ocean total alkalinity and dissolved inorganic carbon measurements from 1993 to 2022: the SNAPO-CO2-v1 dataset

Since 2004, the Service facility SNAPO-CO2 (Service National d’Analyse des Paramètres Océaniques du CO2) housed by the LOCEAN laboratory (Paris, France) has been in charge for the analysis of Total Alkalinity (AT) and Total dissolved inorganic carbon (CT) of seawater samples on a series of cruises or ships of opportunity conducted in different regions in the frame of French projects. More than 44000 observations are synthetized in this work. Sampling was performed either from CTD-Rosette casts (Niskin bottles) or collected from the ship’s seawater supply (intake at about 5m depth). After completion of each cruise, discrete samples were returned back at LOCEAN laboratory and stored in a dark room at 4 °C before analysis generally within 2-3 months after sampling (sometimes within a week).  AT and CT were analyzed simultaneously by potentiometric titration using a closed cell (Edmond, 1970). Certified Reference Materials (CRMs) provided by Pr. A. Dickson (Scripps Institution of Oceanography, San Diego, USA) were used to calibrate the measurements. The same instrumentation was used for underway measurements during OISO cruises (https://doi.org/10.18142/228) and OISO AT-CT data for 1998-2018 in the South Indian Ocean added in this synthesis.

The synthesis is organized in two files (one for Global ocean and the Coastal Zones, one for the Mediterranean Sea) with the same format:

Cruise name, Ship name, day, month, year, hour, minute, second, latitude, longitude, depth, AT (µmol/kg), Flag-AT, CT (µmol/kg), Flag-CT, Temperature (°C), Flag-Temp, Salinity (PSU), Flag-Salinity, nsample/cruise, nsample on file, sampling method.

Since 2004, the Service facility SNAPO-CO2 (Service National d’Analyse des Paramètres Océaniques du CO2) housed by the LOCEAN laboratory (Paris, France) has been in charge for the analysis of Total Alkalinity (AT) and Total dissolved inorganic carbon (CT) of seawater samples on a series of cruises or ships of opportunity conducted in different regions in the frame of French projects. More than 44000 observations are synthetized in this work. Sampling was performed either from CTD-Rosette casts (Niskin bottles) or collected from the ship’s seawater supply (intake at about 5m depth). After completion of each cruise, discrete samples were returned back at LOCEAN laboratory and stored in a dark room at 4 °C before analysis generally within 2-3 months after sampling (sometimes within a week).  AT and CT were analyzed simultaneously by potentiometric titration using a closed cell (Edmond, 1970). Certified Reference Materials (CRMs) provided by Pr. A. Dickson (Scripps Institution of Oceanography, San Diego, USA) were used to calibrate the measurements. The same instrumentation was used for underway measurements during OISO cruises (https://doi.org/10.18142/228) and OISO AT-CT data for 1998-2018 in the South Indian Ocean added in this synthesis.

The synthesis is organized in two files (one for Global ocean and the Coastal Zones, one for the Mediterranean Sea) with the same format:

Cruise name, Ship name, day, month, year, hour, minute, second, latitude, longitude, depth, AT (µmol/kg), Flag-AT, CT (µmol/kg), Flag-CT, Temperature (°C), Flag-Temp, Salinity (PSU), Flag-Salinity, nsample/cruise, nsample on file, sampling method.

Disciplines

Chemical oceanography, Physical oceanography

Keywords

Ocean, total alkalinity, total dissolved inorganic carbon, temperature, salinity

Location

79N, -73S, 180E, -180W

Devices

For each seawater sample, AT and CT were analyzed simultaneously by potentiometric titration using a closed cell (Edmond, 1970); concentrations calculated following Dickson et al (2007). https://doi.org/10.1016/0011-7471(70)90038-0

Edmond, J. M.: High precision determination of titration alkalinity and total carbon dioxide content of sea water by potentiometric titration, Deep-Sea Res., 17, 737–750, https://doi.org/10.1016/0011-7471(70)90038-0, 1970.

Dickson, A.G., Sabine, C.L., Christian, J.R.: Guide to Best Practices for Ocean CO2 Measurements. PICES Special, Publication 3, p. 191, 2007. https://www.ncei.noaa.gov/access/ocean-carbon-acidification-data-system/oceans/Handbook_2007.html

Data

FileSizeFormatProcessingAccess
AT-CT for the Mediterranean Sea (1998-2021 data)
1 MoXLS, XLSXQuality controlled data
AT-CT for the Global Ocean (1993-2022 data)
4 MoXLS, XLSXQuality controlled data
How to cite
Metzl Nicolas, Fin Jonathan, Lo Monaco Claire, Mignon Claude, Alliouane Samir, Antoine David, Bourdin Guillaume, Boutin Jacqueline, Bozec Yann, Conan Pascal, Coppola Laurent, Douville Eric, Durrieu de Madron Xavier, Gattuso Jean-Pierre, Gazeau Frédéric, Golbol  Melek, Lansard Bruno, Lefèvre Dominique, Lefèvre Nathalie, Lombard Fabien, Louanchi Férial, Merlivat Liliane, Olivier Léa, Petrenko Anne, Petton Sébastien, Pujo-Pay Mireille, Rabouille Christophe, Reverdin Gilles, Ridame Céline, Tribollet Aline, Vellucci Vincenzo, Wagener Thibaut, Wimart-Rousseau Cathy (2023). A synthesis of ocean total alkalinity and dissolved inorganic carbon measurements from 1993 to 2022: the SNAPO-CO2-v1 dataset. SEANOE. https://doi.org/10.17882/95414
In addition to properly cite this dataset, it would be appreciated that the following work(s) be cited too, when using this dataset in a publication :
Metzl Nicolas, Fin Jonathan, Lo Monaco Claire, Mignon Claude, Alliouane Samir, Antoine David, Bourdin Guillaume, Boutin Jacqueline, Bozec Yann, Conan Pascal, Coppola Laurent, Diaz Frédéric, Douville Eric, Durrieu de Madron Xavier, Gattuso Jean-Pierre, Gazeau Frédéric, Golbol Melek, Lansard Bruno, Lefèvre Dominique, Lefèvre Nathalie, Lombard Fabien, Louanchi Férial, Merlivat Liliane, Olivier Léa, Petrenko Anne, Petton Sébastien, Pujo-Pay Mireille, Rabouille Christophe, Reverdin Gilles, Ridame Céline, Tribollet Aline, Vellucci Vincenzo, Wagener Thibaut, Wimart-Rousseau Cathy (2024). A synthesis of ocean total alkalinity and dissolved inorganic carbon measurements from 1993 to 2022: the SNAPO-CO2-v1 dataset. Earth System Science Data, 16 (1). https://doi.org/10.5194/essd-16-89-2024

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