Numerical Simulations of Uptake of Anthropogenic Co2 in the North Pacific

Abstract

AbstractA basin‐wide ocean general circulation model with the open southern boundary condition is employed to study the uptake and distribution of anthropogenic CO2in the North Pacific, which is compared with the simulated results from the rigid southern boundary model. Simulated results show that the both western North Pacific and eastern equatorial Pacific are two important sinks of anthropogenic CO2. Larger isopycnal diffusivity produces larger exchange fluxes of anthropogenic CO2in the western North Pacific but smaller fluxes in the equatorial region. Compared with the results from the rigid boundary model, the air‐sea exchange flux of anthropogenic CO2 is larger in these two regions in the open boundary model. During the period 1800~1997, the North Pacific has taken up 23.75 GtC of anthropogenic CO2 in RUN1. The subpolar region is an important export region of the absorbed anthropogenic CO2, where 38%~54% of the absorbed anthropogenic CO2 is transported to other regions, whereas the region of 20°N~30°N is an important storing region, which amounts to 24% of the total storage in the North Pacific. The open boundary has a significant impact on the uptake and storage of anthropogenic CO2 in the area south of 10°N. Compared with the data‐based estimate, although the model underestimates the penetration of anthropogenic CO2 in the western North Pacific and overestimates the penetration in the eastern North Pacific, the model generally well estimates the storage of anthropogenic CO2 in the North Pacific.