Understanding the exposure of the nation’s living marine resources to ocean acidification is a primary goal for the observing portfolio supported by the NOAA OAP. 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 works to enhance the nation’s observing capacity in order to better understand the nation’s vulnerability to continued ocean and Great Lakes acidification. This effort is made possible by working with many line offices and programs within NOAA, partnering with federal and state agencies, and academic and private institutions.
Monitoring for ocean acidification demands high quality observations that allow for full characterization of how ocean chemistry is changing in response to ocean acidification. When people typically think of ocean acidification, they think of pH. However, ocean acidification affects several aspects of the carbonic acid system (pH, CO2 partial pressure (pCO2), carbonate ion availability, total dissolved inorganic carbon (DIC) ) each potentially affecting marine life in different ways. Fully constraining the carbonate system demands not only measuring temperature and salinity, but also knowledge of at least two of four measurable dissolved inorganic carbon parameters: pH, DIC, total alkalinity, and/or the pCO2. Our autonomous fixed and underway OA platforms build on a network of moorings which were originally designed to measure the flux of CO2 into the ocean. More recently, 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 throughout most of the coastal U.S. Large Marine Ecosystems. 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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