Repeat hydrographic surveys, ship-based surface observations, and time series stations (mooring and ship-based) in the Atlantic, Pacific, and Indian Oceans, have allowed us to begin to understand the long-term changes in the carbonate chemistry of the oceans in response to ocean acidification. NOAA’s Ocean Acidification Program aims to enhance these activities and increase the mooring-based time series network in order to advance the understanding of the impacts on, and predict changes in, the Earth's environment as a consequence of continued ocean and Great Lakes acidification. This effort is made possible by working with many line offices and programs within NOAA, partnering with federal agencies, and academic and private institutions.
Monitoring for ocean acidification demands high quality observations that allow for full constraint of the carbonic acid system. When people typically think of ocean acidification, they think of pH. However, fully constraining the carbonate system demands not only measuring temperature and salinity, but also knowledge of at least two of four measureable dissolved inorganic carbon parameters: pH, dissolved inorganic carbon (DIC), total alkalinity, and/or the partial pressure of CO2 (pCO2). Our autonomous fixed and underway OA platforms build on a network of moorings which were originally focused on measuring the flux of CO2 into the ocean. pH has been added to these platforms in an effort to estimate the calcium carbonate saturation state of the waters. In addition, dedicated geochemical ship survey efforts are employed to monitor all four parameters from water samples collected in both surface and deep water environments along coastal waters of the U.S.. Dissolved oxygen (O2), is also a common measurement offering insight into the local biogeochemical controls on OA dynamics. Measuring these variables offers insight into the rate of flux of CO2 into the ocean from the atmosphere, and how that flux affects carbonate chemistry, saturation state , and the biological status and feedbacks of various ecosystems.
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Credit: Cathy Cosca, PMEL
The map above depicts current NOAA OA observing efforts currently underway in red circles. Current tracks of volunteer observing ships (VOSs) are shown by green lines. VOSs are ships travelling for commercial or non-scientific purposes that have been equipped with instruments that measure temperature, salinity and pCO2 with automated carbon dioxide analyzers as well as thermosalinographs (TSGs). These greatly enhance the area in which carbon data can be collected. The blue lines depict hydrographic research cruises dedicated to collect OA samples.
There are many approaches and platforms from which these observations can be made. To find out more about the various instruments currently used and being developed by NOAA OA researchers and partners explore the various links to the right.
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