GLOBAL OCEAN DATA ANALYSIS PROJECT   www.glodap.info    Latest product release    Background and history		SURFACE OCEAN CO2 ATLAS   www.socat.info    Latest product release    Background and history

SOCATv2025 released on 5 June 2025

SOCAT version 2025 has quality-controlled in situ surface ocean fCO₂ (fugacity of CO₂₎ measurements made on ships, moorings, autonomous and drifting surface platforms for the global ocean and coastal seas from 1957 to 2024. The latest update of the community-led Surface Ocean CO2 Atlas (www.socat.info), version 2025, contains 41.4 million, quality-controlled, in situ surface ocean fCO2 measurements with an estimated uncertainty of better than 5 μatm collected between 1957 and 2024, which constitute the main SOCAT synthesis and gridded products (Fig. 1b, 2a, 2b).

We want to thank all >100 data contributors, quality controllers and other contributors who made SOCAT version 2025 possible, and acknowledge the continued leadership of Dorothee Bakker (UEA, UK) in producing the annual SOCAT release.

Click here to download the SOCAT version 2025 release poster

GLODAPv2.2023 released in October 2023

The Global Ocean Data Analysis Project (GLODAP) data product provides access to quality controlled surface to bottom ocean biogeochemical data, with an emphasis on seawater inorganic carbon. GLODAPv2.2023 is an update of the previous version, with 23 additional cruises and includes measurements from more than 1.4 million water samples from the global oceans collected on 1108 cruises. The data for the 13 core variables have undergone extensive quality control, especially systematic evaluation of bias. The data are available in two formats: (i) as submitted by the data originator but updated to WOCE exchange format and (ii) as a merged data product with adjustments applied to minimize bias.

The original data, their documentation and doi codes are available at the Ocean Carbon Data System of NOAA NCEI. This site also provides access to the merged data product, which is provided as a single global file and as four regional ones, and access to the GLODAPv2.2023 ODV collection.

GLODAP: Background and history

Synthesis of ocean interior carbon and carbon-relevant data has been supported by IOCCP since the beginning of the project. Such data are of fundamental importance for accurate assessments of oceanic carbon inventories and uptake rates and for model validation. Over time, three efforts were initiated: GLODAP(v1.1), CARINA and PACIFICA.

All follow rigorous and ever-improving data quality control (QC) procedures to assure the highest possible internal data quality and consistency with other efforts. Key members of the international marine CO₂ community over the past 4 years were assembling the new global carbon data product, Global Ocean Data Analysis v2 (GLODAPv2). This product assembles all past carbon and carbon-relevant data products covering interior ocean into one harmonized data package. Specifically the data from the previously assembled products CARINA, GLODAP v1.1 and PACIFICA. Additionally data from almost two hundred ”new” cruises were added to this collection. IOCCP continues to support this challenging effort. 

GLOBAL OCEAN DATA ANALYSIS PROJECT

The GLobal Ocean Data Analysis Project (GLODAP) is a cooperative effort to coordinate global synthesis projects funded through the U.S. National Oceanic and Atmospheric Administration (NOAA), the U.S. Department of Energy (DOE), and the National Science Foundation (NSF) as part of the Joint Global Ocean Flux Study - Synthesis and Modeling Project (JGOFS-SMP). Cruises conducted as part of the World Ocean Circulation Experiment (WOCE), JGOFS, and the NOAA Ocean-Atmosphere Exchange Study (OACES) over the decade of the 1990s have created an oceanographic database of unparalleled quality and quantity. These data provide an important asset to the scientific community investigating carbon cycling in the oceans. The central objective of this project is to generate a unified data set to help determine the global distributions of both natural and anthropogenic inorganic carbon, including radiocarbon. These estimates provide an important benchmark against which future observational studies will be compared. They also provide tools for the direct evaluation of numerical ocean carbon models.

ATLANTIC OCEAN CARBON SYNTHESIS GROUP

This project was initiated at the IOCCP-CarboOcean Initial Atlantic Ocean Carbon Synthesis Meeting, June 28-30 2006, Laugarvatn, Iceland. The meeting brought together 23 participants from 9 countries with expertise ranging from ship-based hydrography and carbon measurements, physical oceanography, surface pCO2 variability, CFC and tracer measurements, O2 on profiling floats, modeling, and data synthesis and management. During the meeting it was decided that the CARINA (Carbon in the Atlantic) data synthesis should be extended to include the Arctic and Southern Oceans. The Workshop participants developed three coordinated synthesis groups and a common data module:

• North Atlantic working group (lead: Are Olsen, Bjerknes Center for Climate Research, Bergen, Norway)
• Atlantic working group (lead: Toste Tanhua, IFM-GEOMAR, Kiel, Germany)
• South Atlantic / Southern Ocean (lead: Mario Hoppema, AWI, Bremerhaven, Germany)
• Data: Robert Key, Princeton University, USA

These groups met three times after the Iceland meeting; in Kiel, Germany (March 2007), Delmenhorst, Germany (December 2007) and Paris, France (June 2008) to tune the methodology and evaluate the results. Further more, an interactive website was developed that allowed the different investigators to upload and view results of the synthesis. By the end of 2008, the CARINA secondary quality control was finalized. After this the individual cruise data in WOCE exchange format, as well as three merged data products, were published on CDIAC (CARINA at CDIAC) and on CCHDO (CARINA at CCHDO). Working documents, and updates on follow-up activities are also available from the CDIAC website. In addition to these data, an ODV collection and Matlab routines to facilitate reading the data was added to the CIDAC site. The documentation of the CARINA project is primarily done through 20 articles published in a special issue in Earth System Science Data.

NORTH PACIFIC CARBON SYNTHESIS GROUP

This synthesis activity was launched with a workshop entitled “Understanding North Pacific Carbon-Cycle Changes: A Data Synthesis and Modeling Workshop”, held in Seattle in June 2004. This workshop was sponsored by NOAA's Global Carbon Cycle Program with additional support from the North Pacific Marine Science Organization (PICES), The Global Carbon Project (GCP), and the University of Washington Program on Climate Changes (UWPCC). This workshop addressed 3 primary questions:

• 1. How are air-sea CO2 fluxes in the North Pacific affected by different modes of variability?
• 2. How and why are the North Pacific distribution patterns of carbon, nutrients and oxygen in the water column changing with time?
• 3. What are the requirements for detecting a climate change signal in the North Pacific carbon cycle?

A special section of the Journal of Geophysical Research entitled “North Pacific Carbon Cycle Variability and Climate Change” was published in 2006 (C. Sabine and N. Gruber, guest editors, Introduction doi:10.1029/2006JC003532). In 2005 this international collaboration was further formalized with the formation of the PICES Section on Carbon and Climate. A major data synthesis effort subsequently got underway. This project was known as PACIFICA and was coordinated by M. Ishii (Japan) and R. Key (United States). This project has adopted many of the methodologies developed by CARINA in the Atlantic and was expected to be completed in early 2013.

SOCAT: Background and history

Net CO₂ absorption by the world’s oceans is known to benefit human-kind by reducing the concentration of this greenhouse gas in the atmosphere, but the increase in ocean carbon also causes ocean acidification endangering marine organisms. Knowledge of year-to-year and decadal changes in oceanic CO₂ uptake are essential for assessing the feedbacks between climate change and the ocean carbon cycle.

In 2007 the international ocean carbon community led by the IOCCP, SOLAS and IMBER initiated the Surface Ocean CO₂ Atlas (SOCAT) project to ensure long-term access to high quality, regularly updated surface ocean CO₂ data. First public release of SOCAT dataset took place on 14 September 2011 providing unrestricted access to 6.3 million surface water fCO₂ (fugacity of carbon dioxide) measurements taken on 1851 cruises from 1968 to 2007. 

Both the raw input data and the recalculated output data are publicly available and the methods used are fully documented on the SOCAT website. The unique aspect of this dataset is that the observations have been combined into a single uniform format and were quality controlled. To make the dataset user-friendly, it is available on the web through a sophisticated online data visualisation and manipulation tool called the Live Access Server. The LAS provides interactive maps that enable users to interrogate the data. Gridded monthly data are also available. Potential applications include carbon budgets, studies of seasonal, year-to-year and decadal variation in oceanic CO₂ uptake, and research into the processes driving these. For a complete list of SOCAT impacts see here.

Regular updates to SOCAT are planned. The IOCCP continues to strongly support SOCAT efforts to further improve and streamline data submission, quality control and access procedures. The latest version of SOCAT is available from www.socat.info.