This work presents the simulated results about the behavior of sequestered CO_2 in the North Pacific and its impact on atmospheric CO_2 from a regional ocean general circulation model (OGCM) with different parameterizations of subgrid mesoscale mixing of tracers. The model domain is the Pacific Ocean north of 21 deg S, and the resolution is 2 deg by 2 deg in the horizontal with 28 vertical levels. The model is forced at the surface by seasonally varying observed wind stress and ocean surface temperature and salinity. After OGCM is run for 500 years to reach an equilibrium state, the model of sequestered CO_2 is integrated together with OGCM. It is assumed that the artificially injected CO_2 is homogeneously mixed into the given grid cell. Assuming that there is only exchange of sequestered CO_2 between the atmosphere and the model ocean, we choose several injection depths to study the role of injection depth in the sequestration of CO_2. Effectiveness index EI and escape factor EF are used to discuss the effectiveness of the storage of CO_2 at the intermediate water of the North Pacific. The results from GM case show that after continuous injection of CO_2 at the intermediate water of the North Pacific. The results from GM case show that after continuous injection of CO_2 for 50 years at the location of 31 deg N, 145 deg E at the depth of 1000 m, EI decreases from 1 to 0.988 while EF increases from 0 to 0.0448. A total amount of 0.166 GtC is released from the ocean, which is about 1.3
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