A systematic and global re-occupation of select hydrographic sections will be conducted with the objective of quantifying changes in storage and transport of heat, fresh water, carbon dioxide (CO2) and related parameters. The program is in support of the CLImate VARiability and predictability (CLIVAR) and Carbon Science Programs, and is a component of a global observing system for the physical climate and carbon system. By integrating the scientific needs of the carbon and hydrography/tracer communities, major synergies and cost savings will be achieved. In addition to efficiency, a coordinated approach will produce scientific advances that exceed those of having individual programs. These advances will contribute to the following overlapping scientific objectives: Data for Model Calibration, Validation and Model Based Synthesis; Carbon System Studies; Heat and Freshwater Storage and Flux Studies; Deep and Shallow Water Mass and Ventilation Studies; and Calibration of Autonomous Sensors. A joint study of the ocean carbon cycle and circulation will help identify critical areas where potential changes in ocean circulation could have serious consequences for future anthropogenic uptake. Global warming-induced changes in the ocean's transport of heat and freshwater, which could affect the circulation, can be followed through long-term measurements. The sections proposed consist of approximately two meridional and two zonal lines in each ocean, for a total of 10 sections over 6 field years. The core measurements include hydrography (CTD, salinity, oxygen, nutrients, L/ADCP, Underway T, S, pCO2, bathymetry, navigation), carbon system (DIC, pCO2. TAlk, pH, DOC, DON), and transient tracers (CFCs, tritium/3He). In addition to the collection of the data, quality control measures will be routinely carried out by providers of reference-quality data. Post-cruise data updates, distribution, and archive will be managed by groups with separate funding. The field work will be integrated with a larger international effort to monitor the ocean's response to climate change.
Broader Impacts: The results will be disseminated broadly to enhance scientific and technological understanding. The program is based on the fundamental concept that data collected belong to the community, and are available to the community at large rather than being proprietary for the investigators involved in the project. The data policy proposed will be stringent and geared towards rapid and open dissemination, and with a clear structure for all data to undergo thorough quality control. Such an ambitious goal requiring this degree of openness has not been tried on a large scale before. The program benefits to society include the collection of a high quality data set, and use of the data to assess climate change. The global program will provide full water column data of climatically significant parameters with decadal coverage. These data will be used to assess climate change by quantifying the uptake and storage of anthropogenic CO2 by the ocean, and contributing to an understanding and models of the processes that control the uptake and transport of CO2 into the ocean's interior. Since these are likely to be the only systematic observations below 2000 m, they will be used to document long term trends in ocean warming, and heat and freshwater fluxes. The data will be a resource for model calibration of the climate system. The proposed program will promote training and learning. It will serve as a community resource for training and entraining graduate students, postdoctoral scientists, and new scientists. Funds are budgeted in the lead proposal for graduate students, post-docs, and young, non-seagoing scientists to participate in each cruise.
