Search for: All records

This dataset includes surface underway chemical, meteorological and physical data collected from Autonomous Surface Vehicle (ASV) Saildrone 1039 (EXPOCODE 316420220901) in the Indian Ocean, Southern Ocean from 2022-09-01 to 2023-04-27. These data include xCO2 SW (wet) - mole fraction of CO2 in air in equilibrium with the seawater at sea surface temperature and measured humidity; H2O SW - Mole fraction of H2O in air from equilibrator; xCO2 Air (wet) - Mole fraction of CO2 in air from airblock, 0.67m (26") above the sea surface at measured humidity; H2O Air - Mole fraction of H2O in air from airblock, 0.67m (26") above the sea surface; Atmospheric pressure at the airblock, 0.67m (26") above the sea surface; Atmospheric pressure at the airblock, 0.67m (26") above the sea surface; Temperature of the Infrared Licor 820 in degrees Celsius; MAPCO2 %O2 - The percent oxygen of the surface seawater divided by the percent oxygen of the atmosphere at 0.67m (26") above the sea surface; Sea Surface Temperature; Sea Surface Salinity; xCO2 SW (dry) - Mole fraction of CO2 in air in equilibrium with the seawater at sea surface temperature (dry air); xCO2 Air (dry) - Mole fraction of CO2 in air at the airblock, 0.67m (26") above the sea surface (dry air); fCO2 SW (sat) - Fugacity of CO2 in air in equilibrium with the seawater at sea surface temperature (100% humidity); fCO2 Air (sat) - Fugacity of CO2 in air at the airblock, 0.67m (26") above the sea surface (100% humidity); dfCO2 - Difference of the fugacity of the CO2 in seawater and the fugacity of the CO2 in air (fCO2 SW - fCO2 Air); pCO2 SW (wet) - Partial Pressure of CO2 in air in equilibrium with the seawater at sea surface temperature (100% humidity); pCO2 Air (wet) - Partial Pressure of CO2 in air at the airblock, 0.67m (26") above the sea surface (100% humidity); dpCO2 - Difference of the partial pressure of CO2 in seawater and air (pCO2 SW - pCO2 Air; pH of Seawater (total scale). The Autonomous Surface Vehicle CO2 (ASVCO2) instruments used to collect these data include Bubble type equilibrator for autonomous carbon dioxide (CO2) measurement, Carbon dioxide (CO2) gas analyzer, Humidity Sensor, and oxygen meter. 

This dataset includes surface underway chemical, meteorological and physical data collected from Autonomous Surface Vehicle (ASV) Saildrone 1038 (EXPOCODE 316420220616) in the Indian Ocean, Southern Ocean from 2022-06-16 to 2022-07-26. These data include xCO2 SW (wet) - mole fraction of CO2 in air in equilibrium with the seawater at sea surface temperature and measured humidity; H2O SW - Mole fraction of H2O in air from equilibrator; xCO2 Air (wet) - Mole fraction of CO2 in air from airblock, 0.67m (26") above the sea surface at measured humidity; H2O Air - Mole fraction of H2O in air from airblock, 0.67m (26") above the sea surface; Atmospheric pressure at the airblock, 0.67m (26") above the sea surface; Atmospheric pressure at the airblock, 0.67m (26") above the sea surface; Temperature of the Infrared Licor 820 in degrees Celsius; MAPCO2 %O2 - The percent oxygen of the surface seawater divided by the percent oxygen of the atmosphere at 0.67m (26") above the sea surface; Sea Surface Temperature; Sea Surface Salinity; xCO2 SW (dry) - Mole fraction of CO2 in air in equilibrium with the seawater at sea surface temperature (dry air); xCO2 Air (dry) - Mole fraction of CO2 in air at the airblock, 0.67m (26") above the sea surface (dry air); fCO2 SW (sat) - Fugacity of CO2 in air in equilibrium with the seawater at sea surface temperature (100% humidity); fCO2 Air (sat) - Fugacity of CO2 in air at the airblock, 0.67m (26") above the sea surface (100% humidity); dfCO2 - Difference of the fugacity of the CO2 in seawater and the fugacity of the CO2 in air (fCO2 SW - fCO2 Air); pCO2 SW (wet) - Partial Pressure of CO2 in air in equilibrium with the seawater at sea surface temperature (100% humidity); pCO2 Air (wet) - Partial Pressure of CO2 in air at the airblock, 0.67m (26") above the sea surface (100% humidity); dpCO2 - Difference of the partial pressure of CO2 in seawater and air (pCO2 SW - pCO2 Air; pH of Seawater (total scale). The Autonomous Surface Vehicle CO2 (ASVCO2) instruments used to collect these data include Bubble type equilibrator for autonomous carbon dioxide (CO2) measurement, Carbon dioxide (CO2) gas analyzer, Humidity Sensor, and oxygen meter. 

Abstract Ocean heat content (OHC) is key to estimating the energy imbalance of the earth system. Over the past two decades, an increasing number of OHC studies were conducted using oceanic objective analysis (OA) products. Here we perform an intercomparison of OHC from eight OA products with a focus on their robust features and significant differences over the Argo period (2005-2019), when the most reliable global scale oceanic measurements are available. For the global ocean, robust warming in the upper 2000 m is confirmed. The 0-300 m layer shows the highest warming rate but is heavily modulated by interannual variability, particularly the El Niño–Southern Oscillation. The 300-700 m and 700-2000 m layers, on the other hand, show unabated warming. Regionally, the Southern Ocean and mid-latitude North Atlantic show a substantial OHC increase, and the subpolar North Atlantic displays an OHC decrease. A few apparent differences in OHC among the examined OA products were identified. In particular, temporal means of a few OA products that incorporated other ocean measurements besides Argo show a global-scale cooling difference, which is likely related to the baseline climatology fields used to generate those products. Large differences also appear in the interannual variability in the Southern Ocean and in the long-term trends in the subpolar North Atlantic. These differences remind us of the possibility of product-dependent conclusions on OHC variations. Caution is therefore warranted when using merely one OA product to conduct OHC studies, particularly in regions and on timescales that display significant differences. 

Abstract Salinity is one of the fundamental ocean state variables and has been used to infer important information about climate change and variability. Previous studies have found inconsistent salinity variations in various objective ocean analyses that are based on the Argo measurements. However, as far as we are aware, a comprehensive assessment of those inconsistencies, as well as robust spatial and temporal features of salinity variability among the Argo-based products, has not been conducted. Here we compare and evaluate ocean salinity variability from five objective ocean analyses that are solely or primarily based on Argo measurements for their overlapping period from 2005 to 2015. We examine the salinity variability at the sea surface and within two depth intervals (0–700 and 700–2000 m). Our results show that the climatological mean is generally consistent among all examined products, although regional discrepancies are evident in the subsurface ocean. The time evolution, vertical structure, and leading EOF modes of salinity variations show good agreement among most of the examined products, indicating that a number of robust features of the salinity variability can be obtained by examining gridded Argo products. However, significant discrepancies in these variations exist, particularly in the subsurface North Atlantic and Southern Oceans. Also, despite the increasing number of Argo floats deployed in the ocean, the discrepancies were not significantly reduced over time. Our analyses, particularly those of the discrepancies between products, can serve as a useful reference for utilizing and improving the existing objective ocean analyses that are based on Argo measurements. 

Abstract: The ocean absorbs one quarter of the global CO2 emissions from human activity. The community-led Surface Ocean CO2 Atlas (www.socat.info) is key for the quantification of ocean CO2 uptake and its variation, now and in the future. SOCAT version 2025 has quality-controlled in situ surface ocean fCO2 (fugacity of CO2) measurements on ships, moorings, sailing yachts, autonomous and drifting surface platforms for the global ocean and coastal seas from 1957 to 2025. The main SOCAT synthesis and gridded products contain fCO2 values with an estimated accuracy of better than 5 μatm. Sensor fCO2 data with an estimated accuracy of better than 10 μatm are separately available. During secondary quality control, marine scientists assign a flag to each data set, as well as WOCE flags of 2 (good), 3 (questionable) or 4 (bad) to individual fCO2 values. Data sets are assigned flags of A and B for an estimated accuracy of better than 2 μatm, flag of C (and D) for an accuracy of better than 5 μatm and a flag of E for an accuracy of better than 10 μatm. Bakker et al. (2016) describe the quality control criteria used from SOCAT version 3 onward. SOCAT quality control cookbooks provide quality control updates (www.socat.info), with (Gkritzalis et al., 2024) used for version 2025. Quality control comments for individual data sets can be accessed via the SOCAT Data Set Viewer (www.socat.info). All data sets, where data quality has been deemed acceptable, have been made public. The main SOCAT synthesis files and the gridded products contain all data sets with an estimated accuracy of better than 5 µatm (data set flags of A to D) and fCO2 values with a WOCE flag of 2. Access to data sets with an estimated accuracy of better than 10 µatm (flag of E) and fCO2 values with flags of 3 and 4 is via additional data products and the Data Set Viewer (Table 8 in Bakker et al., 2016). SOCAT publishes a global gridded product with a 1° longitude by 1° latitude resolution without gap filling. A second product with a higher resolution of 0.25° longitude by 0.25° latitude is available for the coastal seas. The gridded products contain all data sets with an estimated accuracy of better than 5 µatm (data set flags of A to D) and fCO2 values with a WOCE flag of 2. Gridded products are available monthly, per year and per decade. Two powerful, interactive, online viewers, the Data Set Viewer and the Gridded Data Viewer (www.socat.info), enable investigation of the SOCAT synthesis and gridded data products. SOCAT data products can be downloaded. Matlab code is available for reading these files. Ocean Data View also provides access to the SOCAT data products (www.socat.info). SOCAT data products are discoverable, accessible and citable. The SOCAT Data Use Statement (www.socat.info) asks users to generously acknowledge the contribution of SOCAT scientists by invitation to co-authorship, especially for data providers in regional studies, and/or reference to relevant scientific articles. It also asks users to cite the relevant SOCAT data set, the relevant methods paper(s), and to use acknowledgement text (https://socat.info/index.php/citing-socat/). The SOCAT website (www.socat.info) provides a single access point for online viewers, downloadable data sets, the Data Use Statement, a list of contributors and an overview of scientific publications on SOCAT and using SOCAT. Automation of data upload and initial data checks have allowed annual releases of SOCAT from version 4 onwards. Automation of metadata upload is ongoing. SOCAT is used for quantification of ocean CO2 uptake and ocean acidification and for evaluation of earth system models and sensor data. SOCAT products inform on ocean CO2 uptake in the annual Global Carbon Budget since 2013. SOCAT is a key element of the World Meteorological Organization’s (WMO) Global Greenhouse Gas Watch (G3W) program and is a key resource for Copernicus’ evaluations. The annual SOCAT releases by the SOCAT scientific community contribute to United Nations (UN) Sustainable Development Goal (SDG) 13 and SDG 14 (Life Below Water), and to the UN Decade of Ocean Science for Sustainable Development. However, since 2022 SOCAT critically relies on support provided by the Pacific Marine Environmental Laboratory of the National Oceanic and Atmospheric Administration in the US. This has been sufficient to keep the basic operation running, however this limited support has resulted in SOCAT data architecture not being updated, leading to a system with limited resilience that is highly vulnerable to external factors. Hundreds of peer-reviewed scientific publications and high-impact reports cite SOCAT. The SOCAT community-led synthesis product is a key step in the value chain based on in situ surface ocean carbon measurements, which provides policy makers with critical information on ocean CO2 uptake for policy makers. The need for accurate knowledge of global ocean CO2 uptake and its (future) variation makes sustained funding of in situ surface ocean CO2 observations and their synthesis imperative.