Saturday, August 29, 2015

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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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The Alaska Ocean Acidification Buoy Network- April 8th, 2013

Scientists at Pacific Marine Environmental Laboratory (PMEL) and the Ocean Acidification Center at University of Alaska Fairbanks maintain four buoys in the Gulf of Alaska and Bering Sea that comprise a network to monitor ocean chemistry in sub-arctic waters.  These high latitude waters are of much interest and concern because cold waters more readily absorb CO2, which causes a decrease pH and saturation state.  Additionally, the  predicted reduction of sea ice in this region can increase the uptake of CO2 due to 1) increased freshwater input from melt-water and rivers 2) more seawater being exposed to the atmosphere to absorb CO2 and 3) alteration of the production and decomposition of organic carbon due to increased surface area of ocean water.  

The effort, led by Jeremy Mathis (PMEL), has successfully deployed three of the four OA monitoring buoys, with only buoy "M2" remaining to be deployed in the Bering Sea. Natalie Monacci and Dan Naber at the University of Alaska have been on the ground and in the water for the past month preparing these instruments for sea.  Pictures above display the scenic view from the platforms deployed thus far.  "GAKOA" is just outside of Resurrection Bay in the Northern Gulf of Alaska.  "SEAK" is in the eastern Gulf of Alaska near Port Conclusion. Finally, "Chiniak" is just south of Kodiak Island.  All three moorings  are streaming real-time data at PMEL, along with all of the other coastal moorings from around the world.

The final buoy in the network, "M2" will be deployed very shortly.  Wishing them the best of luck as the Alaska Ocean Acidification Buoy Network becomes a reality!

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