An Argo-Derived Background Diffusivity Parameterization for Improved Ocean Simulations in the Tropical Pacific

Model biases are substantial in ocean and coupled ocean-atmosphere simulations in the tropical Pacific Ocean, including a too cold tongue and too diffuse thermocline. These biases can be partly attributed to vertical mixing parameterizations in which the background diffusivity depiction has great un...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Zhu, Yuchao, Zhang, Rong-Hua
Format: Report
Language:English
Published: AMER GEOPHYSICAL UNION 2018
Subjects:
fine-scale parameterizations
diapycnal diffusivity
MOM5
Geology
Geosciences
Multidisciplinary
COUPLED CLIMATE MODEL
TURBULENT DISSIPATION
FINESCALE PARAMETERIZATIONS
GENERAL-CIRCULATION
EQUATORIAL PACIFIC
INTERNAL WAVES
SOUTHERN-OCEAN
FINE-STRUCTURE
COLD-TONGUE
BIASES
Pacific
Southern Ocean
Online Access:http://ir.qdio.ac.cn/handle/337002/158099
https://doi.org/10.1002/2017GL076269
Description
Summary:Model biases are substantial in ocean and coupled ocean-atmosphere simulations in the tropical Pacific Ocean, including a too cold tongue and too diffuse thermocline. These biases can be partly attributed to vertical mixing parameterizations in which the background diffusivity depiction has great uncertainties. Here based on the fine-scale parameterization, the Argo data are used to derive the spatially varying background diffusivity, with a magnitude of O(10(-6) m(2) s(-1)) in the most area of tropical Pacific. This new scheme is then employed into the version 5.1 of the Modular Ocean Model-based ocean-only and coupled models, resulting in substantial improvements in ocean simulations, including a more realistic cold tongue and equatorial thermocline. The improved simulations can be attributed to the reduced cooling effects induced by weakened equatorial upwelling. Additionally, the subsurface cooling effect is attributed to the reduced heat transfer from the upper layer to the subsurface layer and the convergence of the colder water from off the equator.

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