Modeling of Ocean Acidification in the Massachusetts Bay/Boston Harbor and over the US Northeast Shelf

Lu Wang1, Changsheng Chen1, Robert C Beardsley2 and Joseph Salisbury II3, (1)University of Massachusetts Dartmouth, New Bedford, MA, United States, (2)WHOI, Woods Hole, MA, United States, (3)University of New Hampshire, Durham, NH, United States
The U.S. northeast coastal ocean is identified as a region that could be significantly influenced by coastal acidification. The enhanced acidification condition in the region changes with short-term variability caused mainly by the seasonality of lower trophic level biological respiration, precipitation minus evaporation, and changes in coastal river discharge and long-term variability due to climate change-induced interannual-decadal fluctuation of atmospheric CO2 loading and the inflow of the cool and less salty water from the upstream. To examine biophysical mechanism for ocean acidification, we have developed a Northeast Biogeochemistry and Ecosystem Model (NeBEM) under the framework of the FVCOM-based ERSEM. This model was first validated for the Mass Bay and Boston Harbor through 1-D and 3-D experiments. Driven by the assimilated physical field output from the Mass Bay-FVCOM, NeBEM was robust to capture the seasonal variability of nutrients, phytoplankton, DO, pH and other geochemistry variables on both off-shore and near-shore monitoring stations. A comparison was also made with the existing Mass Bay water quality model (UG-RCA). With improved benthic-water interaction processes, NeBEM showed a better performance than UG-RCA in the near-shore region and inside Boston Harbor. We are extending NeBEM to cover the entire northeast coastal region. NeBEM has provided us a scientific tool to distinguish the relative importance of physical, geochemical and biological processes to the change of ocean acidification in the Mass Bay and over the northeast shelf.