A regional ocean general circulation model with three different parameterizations of subgrid
mesoscale mixing of tracers is used to study the general circulation and the distributions of water
masses and chlorofluorocarbons (CFCs) in the North Pacific under the forcing conditions of both
annual mean climatology and perpetual wintertime (March) climatology. With horizontal mixing
scheme (HOR), the model cannot well simulate formation of the North Pacific Intermediate Wa
ter (NPIW). The NPIW is well simulated in the model with isopycnal mixing scheme. Changes in
the surface forcing from the annual mean climatology to the perpetual wintertime climatology
generally lead to the improvement of water mass distributions. This study takes CFC-11 as a
representative of passive tracers to discuss the influences of three different parameterizations of
mixing of tracers and of the formation of NPIW on its distribution in the North Pacific. The
simulated results, including the vertical structure and column inventories of CFC-11, from the
perpetual wintertime forcing are better than those from the annual mean forcing, compared with
observations. With HOR, the model underestimates the oceanic uptake of CFCs in the North
Pacific. Under the perpetual wintertime forcing, the isopycnal mixing scheme with and without
eddy-induced transport velocity gives reasonable agreement with observed results. However, a
large difference still exists in some areas, particularly in the western North Pacific, which is
probably an important sink of atmospheric CFCs.
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