A New Second-Order Turbulence Closure Scheme for Modeling the Oceanic Mixed Layer

D’Alessio, S. J. D.; Abdella, Kenzu; McFarlane, N. A.

doi:10.1175/1520-0485(1998)028<1624:ansotc>2.0.co;2

Cited by 54 publications

(35 citation statements)

References 48 publications

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“…Other studies investigated second-moment turbulence closure models by including the CL vortex force in the TKE equation (D'Alessio et al 1998), the dissipation length scale (Kantha and Clayson 2004), and the stability functions (Harcourt 2013(Harcourt , 2015. The additional turbulent flux down the gradient of the Stokes drift is a key component to the modifications presented by Harcourt (2013Harcourt ( , 2015.…”

Section: Geophysical Turbulence Closure Modelsmentioning

confidence: 99%

Langmuir Turbulence Parameterization in Tropical Cyclone Conditions

Reichl

Wei

Hara

et al. 2016

Journal of Physical Oceanography

103

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The Stokes drift of surface waves significantly modifies the upper-ocean turbulence because of the CraikLeibovich vortex force (Langmuir turbulence). Under tropical cyclones the contribution of the surface waves varies significantly depending on complex wind and wave conditions. Therefore, turbulence closure models used in ocean models need to explicitly include the sea state-dependent impacts of the Langmuir turbulence. In this study, the K-profile parameterization (KPP) first-moment turbulence closure model is modified to include the explicit Langmuir turbulence effect, and its performance is tested against equivalent large-eddy simulation (LES) experiments under tropical cyclone conditions. First, the KPP model is retuned to reproduce LES results without Langmuir turbulence to eliminate implicit Langmuir turbulence effects included in the standard KPP model. Next, the Lagrangian currents are used in place of the Eulerian currents in the KPP equations that calculate the bulk Richardson number and the vertical turbulent momentum flux. Finally, an enhancement to the turbulent mixing is introduced as a function of the nondimensional turbulent Langmuir number. The retuned KPP, with the Lagrangian currents replacing the Eulerian currents and the turbulent mixing enhanced, significantly improves prediction of upper-ocean temperature and currents compared to the standard (unmodified) KPP model under tropical cyclones and shows improvements over the standard KPP at constant moderate winds (10 m s 21 ).

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Section: Geophysical Turbulence Closure Modelsmentioning

confidence: 99%

Langmuir Turbulence Parameterization in Tropical Cyclone Conditions

Reichl

Wei

Hara

et al. 2016

Journal of Physical Oceanography

103

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“…A fourth-order low-pass Butterworth filter with a 6 h cutoff period was deployed twice, once forward and once backward, to minimise phase distortion for the measurement errors and high-frequency motion, following Mitchell et al (2005), Jarosz et al (2007) and Teague et al (2007). vertically upwards, and assuming the flow is homogeneous in the horizontal, the rotational hydrodynamic equation and temperature equation can be written as (D'Alessio et al, 1998): where u and v are the velocity components with respect to the x and y directions, θ is potential temperature, K M is eddy viscosity, K H is eddy diffusivity, f is the Coriolis parameter, Q SR is solar shortwave radiation, ρ w is water density and c pw is water heat capacity at constant pressure.…”

Section: Typhoon Megi and Observational Datamentioning

confidence: 99%

Drag coefficients derived from ocean current and temperature profiles at high wind speeds

Zou

Zhao

Tian

et al. 2018

Tellus A: Dynamic Meteorology and Oceanography

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Two bottom-up methods based on the turbulence closure and bulk model were utilised to estimate drag coefficients at high wind speeds based on ocean current and temperature profiles observed by two subsurface buoys during Typhoon Megi in the South China Sea. A numerical experiment was conducted using the turbulence closure model to test the impact of missing measurements in the upper mixed layer on the wind stress estimate and reconstruction of the upper ocean current. The results were sufficiently robust after several time steps. The wind stresses derived from the two methods were consistent with each other. Wind stress increased quickly with increasing wind force, and then was constant. A parametric typhoon wind model was applied to obtain the wind field and estimate the corresponding drag coefficient. The results showed that the drag coefficient increased to a maximum at a critical wind speed of about 30 m s −1 , and then levelled off with increasing wind speed. The uncertainty of the maximum drag coefficient was about ±0.5 due to neglect of nonlinear terms, the uncertainty of the model wind speeds and the drag coefficient. The critical wind speed for the maximum drag coefficient varied by at least ±5 m s −1 . The uncertainty of the drag coefficient parameterisation was about 24% due to wind speed. These results indicate that a bottom-up method can be used to estimate drag coefficients at the forced stage during the passage of typhoons or hurricanes.

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“…In our study, MESO-NH is coupled to a one-dimensional ocean model (Gaspar et al, 1990) that has been shown to represent relatively well the vertical mixed layer structure and the SST evolution (Blanke and Delecluse, 1993;Alexander et al, 2000). Several ocean turbulence models are based on the Gaspar et al (1990) model equations (D'Alessio et al, 1998;Giordani et al, 2006). Using this air-sea coupled modelling system, the aim of the present article is to examine the ocean response to the high-resolution atmospheric forcing imposed during Mediterranean heavy precipitation events.…”

Section: Introductionmentioning

confidence: 99%

Two‐way one‐dimensional high‐resolution air–sea coupled modelling applied to Mediterranean heavy rain events

Brossier

Ducrocq

Giordani

2008

Quart J Royal Meteoro Soc

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South-eastern France is prone to heavy rain events during the autumn. For these extreme precipitation events, the Mediterranean Sea fuels the atmospheric boundary layer in heat and moisture and sometimes contributes to flooding, owing to the large swell and waves produced in these situations. The aim of this study is to examine how the severe atmospheric conditions over the sea associated with these events alter the ocean mixed layer, and what feedback the ocean contributes to the precipitation events.To address these questions, a high-resolution air-sea coupled system is developed between the atmospheric MESO-NH model and a one-dimensional ocean model. It is applied for short range (24 h) and high-resolution (2-3 km) simulations of three representative torrential rainfall events: 12-13 November 1999 (Aude case), 8-9 September 2002 (Gard case) and 3 December 2003 (Hérault case). In those meteorological situations characterized by moderate to intense low-level winds, the Mediterranean Sea globally loses energy, to the benefit of the convective precipitating systems. The result is an overall decrease of the thermal content all along the simulation of the events. Significant cooling and deepening of the ocean mixed layer are found in the areas of intense low-level winds. A notable result of the study concerns the impact of the torrential rainfall on the ocean mixed layer. The most important disturbances of the ocean mixed layer are indeed found underneath the heavy precipitation. The salt content is decreased all along the ocean mixed layer depth, but more significantly in the first ten metres near the air-sea interface, with the formation of a salt barrier.By performing both two-way and one-way coupled simulations, it is found that the interactive coupling tends to moderate both the atmospheric and ocean responses compared with the one-way mode. The differences between the two-way and one-way coupled simulations are, however, found to be relatively small considering the atmospheric short-range forecast.

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A New Second-Order Turbulence Closure Scheme for Modeling the Oceanic Mixed Layer

Cited by 54 publications

References 48 publications

Langmuir Turbulence Parameterization in Tropical Cyclone Conditions

Langmuir Turbulence Parameterization in Tropical Cyclone Conditions

Drag coefficients derived from ocean current and temperature profiles at high wind speeds

Two‐way one‐dimensional high‐resolution air–sea coupled modelling applied to Mediterranean heavy rain events

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