Coupling of Physical and Bio-Geochemical Process and Monitoring Ocean Circulation Using Data Assimilation System

The Subarctic region in the North Pacific is a region of high activity of the ocean ecosystem, so an estimation of the amount of CO2 absorption is very important. It is well known that CO2 is absorbed in spring and summer because of active blooming; however, CO2 is released from ocean in the winter because a deepening of the mixed layer lead the entrainment of CO2 rich water in subsurface layer into the surface layer. To estimate the amount of winter emission, the CO2 distribution of the subsurface layer is necessary through the entrainment process. The data assimilation system is constructed to estimate the subsurface CO2 distribution using an adjoint method. As observation data, surface CO2 pressure data and carbonate is assimilated into a simple ocean model, which includes mixed Coupling of Physical and Bio-Geochemical Process and Monitoring Ocean Circulation Using Data Assimilation System