This is the final version of the article. Available from Wiley via the DOI in this record. ; The accumulation of carbon within the Weddell Gyre and its exchanges across the gyre boundaries are investigated with three recent full-depth oceanographic sections enclosing this climatically important region. The combination of carbon measurements with ocean circulation transport estimates from a box inverse analysis reveals that deepwater transports associated with Warm Deep Water (WDW) and Weddell Sea Deep Water dominate the gyre's carbon budget, while a dual-cell vertical overturning circulation leads to both upwelling and the delivery of large quantities of carbon to the deep ocean. Historical sea surface pCO2 observations, interpolated using a neural network technique, confirm the net summertime sink of 0.044 to 0.058±0.010PgCyr-1 derived from the inversion. However, a wintertime outgassing signal similar in size results in a statistically insignificant annual air-to-sea CO2 flux of 0.002±0.007PgCyr-1 (mean 1998-2011) to 0.012±0.024PgCyr-1 (mean 2008-2010) to be diagnosed for the Weddell Gyre. A surface layer carbon balance, independently derived from in situ biogeochemical measurements, reveals that freshwater inputs and biological drawdown decrease surface ocean inorganic carbon levels more than they are increased by WDW entrainment, resulting in an estimated annual carbon sink of 0.033±0.021PgCyr-1. Although relatively less efficient for carbon uptake than the global oceans, the summertime Weddell Gyre suppresses the winter outgassing signal, while its biological pump and deepwater formation act as key conduits for transporting natural and anthropogenic carbon to the deep ocean where they can reside for long time scales. ; NERC ; European Union CarboOcean ; CarboChange
This is the final version of the article. Available from the publisher via the DOI in this record. ; The Surface Ocean CO2 Atlas (SOCAT) is a synthesis of quality-controlled fCO2 (fugacity of carbon dioxide) values for the global surface oceans and coastal seas with regular updates. Version 3 of SOCAT has 14.7 million fCO2 values from 3646 data sets covering the years 1957 to 2014. This latest version has an additional 4.6 million fCO2 values relative to version 2 and extends the record from 2011 to 2014. Version 3 also significantly increases the data availability for 2005 to 2013. SOCAT has an average of approximately 1.2 million surface water fCO2 values per year for the years 2006 to 2012. Quality and documentation of the data has improved. A new feature is the data set quality control (QC) flag of E for data from alternative sensors and platforms. The accuracy of surface water fCO2 has been defined for all data set QC flags. Automated range checking has been carried out for all data sets during their upload into SOCAT. The upgrade of the interactive Data Set Viewer (previously known as the Cruise Data Viewer) allows better interrogation of the SOCAT data collection and rapid creation of high-quality figures for scientific presentations. Automated data upload has been launched for version 4 and will enable more frequent SOCAT releases in the future. Highprofile scientific applications of SOCAT include quantification of the ocean sink for atmospheric carbon dioxide and its long-term variation, detection of ocean acidification, as well as evaluation of coupled-climate and ocean-only biogeochemical models. Users of SOCAT data products are urged to acknowledge the contribution of data providers, as stated in the SOCAT Fair Data Use Statement. This ESSD (Earth System Science Data) "living data" publication documents the methods and data sets used for the assembly of this new version of the SOCAT data collection and compares these with those used for earlier versions of the data collection (Pfeil et al., 2013; Sabine et al., 2013; Bakker et al., 2014). Individual data set files, included in the synthesis product, can be downloaded here: doi:10.1594/PANGAEA.849770. The gridded products are available here: doi:10.3334/CDIAC/OTG.SOCAT-V3-GRID. ; Research vessel Tiglax in Columbia Bay, Alaska, is shown on the website for SOCAT version 3. The Columbia Glacier can be seen at the head of the bay, as well as calved ice from the glacier. The photo was taken by Wiley Evans. Pete Brown (National Oceanography Centre Southampton, UK) designed the SOCAT logo. IOCCP (via a US National Science Foundation grant (OCE-124 3377) to the Scientific Committee on Oceanic Research), IOC-UNESCO (International Oceanographic Commission of the United Nations Educational, Scientific and Cultural Organization), SOLAS and IMBER provided travel and meeting support. Funding was received from the University of East Anglia (UK), the Bjerknes Centre for Climate Research (Norway), the Geophysical Institute at the University of Bergen (Norway) and the University of Washington (US). The US National Oceanic and Atmospheric Administration (NOAA) made important financial contributions via the Climate Observation Division of the Climate Program Office, the NOAA Ocean Acidification Program, the NOAA Pacific Marine Environmental Laboratory (PMEL), the NOAA Atlantic Oceanographic and Meteorological Laboratory (AOML) and the NOAA Earth System Research Laboratory. Funding was also received from Oak Ridge National Laboratory (US), PANGAEA® Data Publisher for Earth and Environmental Science (Germany), the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (Germany), the Antarctic Climate and Ecosystems Cooperative Research Centre (Australia), the National Institute for Environmental Studies (Japan) and Uni Research (Norway). Research projects making SOCAT possible included the European Union projects CarboChange (FP7 264879), GEOCARBON (FP7 283080) and AtlantOS (633211), the UK Ocean Acidification Research Programme (NE/H017046/1; funded by the Natural Environment Research Council (NERC) and the Departments for Energy and Climate Change and for Environment, Food and Rural Affairs (Defra)) and the UK Shelf Sea Biogeochemistry Blue Carbon project (NE/K00168X/1; funded by NERC and Defra). Numerous government and funding agencies financially supported SOCAT, notably the Australian International Marine Observing System, the U.S. Geological Survey, the National Aeronautics and Space Administration (NASA) (US), the European Space Agency, the German Federal Ministry of Education and Research (BMBF projects 01LK1224J, 01LK1101C, 01LK1101E, ICOS-D), the Japanese Ministry of the Environment, the Royal Society of New Zealand via the New Zealand–Germany Science and Technology Programme, the Norwegian Research Council (SNACS, 229752), the Swedish Research Council (project 2004-4034) and the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (Formas, project 2004- 797). This is PMEL contribution number 4441. Finally, we thank the two anonymous reviewers for their thoughtful, constructive and insightful reviews
