GO-SHIP A13.5

The U.S. Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP) is part of the international GO-SHIP program , which carries out a systematic and global re-occupation of select hydrographic sections to quantify changes in storage and transport of heat, fresh water, carbon dioxide (CO2), and related parameters. By integrating the scientific needs of the carbon and hydrography/tracer communities, major synergies and cost savings are achieved. In addition to efficiency, the coordinated approach produces scientific advances that exceed those of individual programs. These advances contribute to the following overlapping scientific objectives: i) Data for Model Calibration and Validation; 2) Carbon System Studies; 3) Heat and Freshwater Storage and Flux Studies; 4) Deep and Shallow Water Mass and Ventilation Studies; and 5) Calibration of Autonomous Sensors. The most important and basic climate system components are the heat, freshwater, and carbon content and transport of the oceans, which directly interact with other essential components of the climate system in the atmosphere and cryosphere. In turn, the associated variability and trends in the ocean's carbon content, carbonate saturation state, oxygen, and nutrients impact its internal biological environment, with notable large-scale regional changes. This joint study of the ocean carbon cycle and circulation is critical to identify critical areas where changes in ocean circulation could have serious consequences for future anthropogenic carbon uptake. Global warming-induced changes in the ocean's transport of heat and freshwater, which could affect the circulation, are being followed through these long-term measurements. Results to date have shown that the abyssal ocean is warming, taking up to 30% of the excess heat in the entire Earth system, leading to changes in circulation patterns and ventilation rates in the upper ocean. The uptake of anthropogenic carbon from the atmosphere to the ocean has been mapped and shows that the oceans are acidifying. Oxygen concentrations are declining in the ocean thermocline, and tropical oxygen minimum zones are expanding. The project is based on the fundamental concept that data collected belong to the community and need to be made quickly and freely available to the community at large through a recognized international data center. The project will continue to promote training and learning for graduate students, postdoctoral scientists, and new scientists in sea-going work. Outreach activities will continue as opportunities arise. By integrating the scientific needs of the carbon, tracer and hydrographic communities, major scientific synergies and cost savings will continue to be achieved. In addition to efficiency, the coordinated approach produces scientific advances that exceed those of having individual programs. The measurements made on this section include hydrography (full-depth vertical profiles of salinity, temperature, oxygen, nutrients, currents), Underway surface temperature, salinity, partial pressure of carbon dioxide (pCO2), air-sea fluxes, bathymetry, navigation), carbon system (dissolved inorganic carbon, pCO2. Total Alkalinity, pH, dissolved organic carbon and nitrogen), and transient tracers. This project will collect the data and perform the quality control measures routinely carried out by providers of reference-quality data. Post-cruise data updates, distribution, and archive will continue to be managed by groups with separate funding. This ongoing project is integrated with a larger international effort to monitor the ocean's response to climate change. The focus of this particular cruise is to determine the changes in anthropogenic CO2, distributions and fluxes in the South Atlantic since the last occupation in 2010 as part of the GO-SHIP program. Decadal variations of CO2 tracer, oxygen, and temperature distributions are strongly influenced by climate change and natural processes. The GO-SHIP cruises are the only means to obtain climate quality data to study changes and impacts in the ocean. This research is co-sponsored by NOAA and NSF.