Pathways of the North Pacific Intermediate Water identified through the tangent linear and adjoint models of an ocean general circulation model

Abstract A basinwide ocean general circulation model of the North Pacific Ocean is used to study the sensitivity of the simulated distributions of water masses, chlorofluorocarbons (CFCs), and bomb carbon-14 isotope (14C) to parameterizations of mesoscale tracer transports. Five simulations are conducted, including a run with the traditional horizontal mixing scheme and four runs with the isopycnal transport parameterization of Gent and McWilliams (GM). The four GM runs use different values of isopycnal and skew diffusivities. Simulated results show that the GM mixing scheme can help to form North Pacific Intermediate Water (NPIW). Greater isopycnal diffusivity enhances formation of NPIW. Although greater skew diffusivity can also generate NPIW, it makes the subsurface too fresh. Results from simulations of CFC uptake show that greater isopycnal diffusivity generates the best results relative to observations in the western North Pacific. The model generally underestimates the inventories of CFCs in the western North Pacific. The results from simulations of bomb 14C reproduce some observed features. Greater isopycnal diffusivity generates a longitudinal gradient of the inventory of bomb 14C from west to east, whereas greater skew diffusivity makes it reversed. It is considered that the ratio of isopycnal diffusivity to skew diffusivity is important. An increase in isopycnal diffusivity increases storage of passive tracers in the subtropical gyre.

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Formation of North Pacific Intermediate Water in Meteorological Research Institute ocean general circulation model: 1. Subgrid-scale mixing and marginal sea fresh water

Journal of Geophysical Research Atmospheres ◽

10.1029/98jc01663 ◽

1998 ◽

Vol 103 (C13) ◽

pp. 30885-30903 ◽

Cited By ~ 21

Author(s):

Goro Yamanaka ◽

Yoshiteru Kitamura ◽

Masahiro Endoh

Keyword(s):

North Pacific ◽

General Circulation ◽

Circulation Model ◽

Ocean General Circulation Model ◽

Intermediate Water ◽

Subgrid Scale ◽

North Pacific Intermediate Water ◽

Meteorological Research Institute ◽

Marginal Sea ◽

Ocean General Circulation

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Simulation of global distribution of rare earth elements in the ocean using an ocean general circulation model

Journal of Oceanography ◽

10.1007/s10872-021-00600-x ◽

2021 ◽

Author(s):

Akira Oka ◽

Hirofumi Tazoe ◽

Hajime Obata

Keyword(s):

North Pacific ◽

General Circulation ◽

North Pacific Ocean ◽

Circulation Model ◽

Ocean General Circulation Model ◽

Vertical Profiles ◽

Coastal Regions ◽

The North ◽

Ocean General Circulation ◽

The North Pacific

AbstractIn this study, we report our ocean general circulation model simulations of the global distribution of rare earth elements (REEs) in the ocean. As previously reported (Oka et al. in Glob Biogeochem Cycles 23:1–16, 2009), the vertical profiles of REEs in the North Pacific Ocean are strongly controlled by the reversible scavenging process, and the systematic differences between REEs can be reproduced in the model by selecting an appropriate model parameter which controls affinity to particles. We here demonstrate that the external REE input from the coastal regions also plays a role in controlling the vertical profiles of dissolved REE and their inter-basin differences. The role of the external inputs is especially important for light REEs, such as neodymium (Nd). The linear increase in Nd concentration in the North Pacific Ocean cannot be sufficiently reproduced by the reversible scavenging alone; rather, a combination of the reversible scavenging and the external inputs is necessary. On the other hand, the distribution of heavy REEs, such as lutetium (Lu), can be broadly reproduced without the external inputs, suggesting that Lu has similarity with conservative nutrient-like tracer. When compared with REE observations compiled from both the recently obtained GEOTRACES dataset and pre-GEOTRACES reported data, our simulations successfully reproduced the overall features of these observations. Observational data suggested that the vertical profiles of REEs are not the same among the basins; our model simulations demonstrate that this feature can be clearly reproduced by considering both the reversible scavenging and the external REE inputs from the coastal regions.

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