Variational Estimation of Wave-affected Parameters in a Two-equation Turbulence Model
NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OCEANOGRAPHY
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A variational method is used to estimate wave-affected parameters in a two-equation turbulence model with assimilating the temperature data into an ocean boundary layer model. Enhancement of turbulent kinetic energy dissipation due to breaking waves is considered. The Mellor-Yamada 2.5 turbulence closure scheme MY-2.5 with the two uncertain wave-affected parameters wave energy factor alpha and Charnock coefficient Beta 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 alpha, Beta can be successfully estimated using the variational method. Second, real temperature profiles from the 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.
- Statistics and Probability
- Fluid Mechanics