Publication Abstracts

Yin 1990

Yin, F., 1990: Numerical Modeling of Ocean Deep Water Circulation. Ph.D. thesis. Columbia University.

A multiple layer ocean model that is physically simple and computationally efficient is developed. The model is essentially geostrophic and hydrostatic in the ocean interior with Rayleigh friction added in boundary layer and equatorial regions. A stably stratified density structure is specified at the static equilibrium, and cross-isopycnal mixing is parameterized as a diffusive flux. The model is forced by latitudinally varying Ekman pumping velocities at the base of the ocean surface Ekman layer and localized deep water sources.

A four layer version of the model has been run in a rectangular basin with 5000 meter depth, extending from 65°S to 65°N latitude and covering 70 degree longitudes. The four layers mimic the major water masses observed in the Atlantic Ocean: thermocline water, intermediate water, North Atlantic Deep Water (NADW) and Antarctic Bottom Water (AABW). For forcing corresponding to the current climate, warm water and cold water circulation routes produced in the model agree with those inferred from observations, e.g., southward flowing NADW overriding northward flowing AABW in the western boundary. A large number of experiments were carried out with the model to test the response of the circulation to climate change. It is shown that subtropical gyres intensify and thermocline depths become shallow when deep water sources increase in intensity, or when more source water is formed from the thermocline water layer than from the intermediate water layer for a fixed formation rate of NADW.

A physical mechanism, of which the NADW source and AABW source interact with each other, is demonstrated. Changes in the formation rate of a deep water source will alter cross-isopycnal flows, especially along the related circulation route, so the extent that the other sources can travel before they detrain completely will also be changed. The model shows a strong interaction between NADW source and AABW source in changing thermocline depth, intensity of subtropical gyres and cross-equatorial transport.

The model illustrates that the creation or reduction of deep water formation rate may decrease or increase the transient response time of the atmosphere because thermocline depths become shallower or deeper, and the poleward meridional heat transport may also increase and decrease to affect the temperature in polar regions.

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BibTeX Citation

@phdthesis{yi06000k,
  author={Yin, F.},
  title={Numerical Modeling of Ocean Deep Water Circulation},
  year={1990},
  school={Columbia University},
  address={New York, N.Y.},
}

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RIS Citation

TY  - THES
ID  - yi06000k
AU  - Yin, F.
PY  - 1990
BT  - Numerical Modeling of Ocean Deep Water Circulation
PB  - Columbia University
CY  - New York, N.Y.
ER  -

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