Ocean Acidification-Category 1: Does the strength of the carbonate pump change with ocean stratification and acidification and how?

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This project will improve the ability to predict the response of the carbonate pump to ocean acidification and stratification through enhanced understanding of the controlling factors of the export of CaCO3 from the surface and cycling through the water column and sediments. Key questions to be addressed are (i) Does the strength of the carbonate pump change in response to ocean acidification and stratification? (ii) Is the CaCO3 export more closely associated with the tightly recycling picoplankton and nanoplankton ecosystems than the blooming microplankton? (iii) What is the role of interactions between organic particle fluxes and the saturation state of seawater with respect to CaCO3 minerals in the dissolution of CaCO3 in the water column and sediments? The above three questions will be addressed in a unified model-observation framework where a suite of global models of the carbonate pump will be objectively assessed using a wide range of observations. An already assembled and analyzed global database of ocean biogeochemical tracers and sediment traps will be combined with 3-D numerical model frameworks. The work will be done using a time-efficient solver that allows for systematic model optimization and sensitivity analyses. This work will be incorporated into earth system models developed by the NOAA Geophysical Fluid Dynamics Laboratory for assessment of the interactive role of marine ecosystems and ocean acidification in future climate. This work will further help to improve our ability to predict the future role of the ocean in absorbing anthropogenic carbon and also elucidate the oceanic contribution to the glacial/interglacial changes in atmospheric pCO2. This diagnostic study as well as the model sensitivity analyses will benefit the ocean observing system by providing guidance on how to better monitor the ocean's response to ocean acidification and stratification. Results will be made available via Princeton University websites, and will be incorporated in the teaching material at Princeton University.