Simulation of bomb ~(14)C distribution in North Pacific

A general basin-wide ocean circulation model with an open boundary condition is used to study the uptake and distribution of bomb ~(14)C in the North Pacific.To study the differences between the models with a close boundary condition and with an open boundary condition,and the effects of different isopycnal diffusivities in the open boundary model,three numerical experiments were performed. Simulated results show that opening the southern boundary of the model can improve the distribution of bomb ~(14)C in the region south of equator dramatically,and that increasing the isopycnal diffusivity can strengthen the formation of the North Pacific Intermediate Water.As a result,the water with a high bomb ~(14)C concentration at the sections,including the section along 165°E in the western North Pacific,has a stronger transport southwards and downwards,which improves the simulated distributions of bomb ~(14)C.Larger isopycnal diffusivity can well reproduce the longitudinal gradients of the bomb ~(14)C column inventory,which coincides with the observations.