Variational Estimation of Wave-Affected Parameters in a Two-Equation Turbulence Model
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Authors
Zhang, Xuefeng
Han, Guijun
Li, Dong
Wu, Xinrong
Li, Wei
Chu, Peter C.
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Date of Issue
2015-05
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Abstract
A variational method is used to estimate wave-affected parameters in a two-equation turbulence model
with assimilation of temperature data into an ocean boundary layer model. Enhancement of turbulent kinetic
energy dissipation due to breaking waves is considered. The Mellor–Yamada level 2.5 turbulence closure
scheme (MY2.5) with the two uncertain wave-affected parameters (wave energy factor a and Charnock
coefficient b) is selected as the two-equation turbulence model for this study. Two types of experiments are
conducted. First,within an identical synthetic experiment framework, the upper-layer temperature ‘‘observations’’
in summer generated by a ‘‘truth’’ model are assimilated into a biased simulation model to investigate if (a, b) can
be successfully estimated using the variational method. Second, real temperature profiles from Ocean Weather
Station Papa are assimilated into the biased simulation model to obtain the optimal wave-affected parameters.
With the optimally estimated parameters, the upper-layer temperature can be well predicted. Furthermore,
the horizontal distribution of the wave-affected parameters employed in a high-order turbulence
closure scheme can be estimated optimally by using the four-dimensional variational method that assimilates
the upper-layer available temperature data into an ocean general circulation model.
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The article of record as published may be found at http://dx.doi.org/10.1175/JTECH-D-14-00087.1
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Oceanography
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Journal of Atmospheric and Oceanic Technology, Volume 32, pp. 528-546.
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.