Turbulence closure: turbulence, waves and the wave-turbulence transition – Part 1: Vanishing mean shear

Baumert, Helmut Z.; Peters, Hartmut

doi:10.5194/os-5-47-2009

Cited by 17 publications

(10 citation statements)

References 44 publications

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“…Once Γ m is known, it can be used to determine the vertical eddy viscosity, A z , to estimate mixing. It has been shown that when Ri > 0.5, turbulence is completely suppressed by stratification and turned into wave energy (Baumert & Peters, ). However, Giddings et al () found this threshold to be as high as 1 in the Snohomish River.…”

Section: Methodsmentioning

confidence: 99%

Intratidal and Fortnightly Variability of Vertical Mixing in a Macrotidal Estuary: The Gironde

2019

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Intratidal and fortnightly variability of turbulence at the mouth of a macrotidal estuary is explored in this study. Profiles of turbulent kinetic energy dissipation were estimated from a Vertical Microstructure Profiler, and velocity shear measurements and current velocities were collected with a vessel‐mounted Acoustic Doppler Current Profiler. Gradient Richardson numbers were quantified using density measurements from a Conductivity, Temperature, Depth profiler and squared vertical shear quantified from current velocities. All measurements were collected over one complete semidiurnal tidal cycle in both neap and spring tide conditions. Vertical eddy viscosity (Az) was quantified from the available data and was used as a proxy for vertical mixing. Results showed intratidal asymmetries in bottom‐generated turbulence during neap with Az larger during ebb tide (∼10−2 m2/s) than flood tide (∼10−3 m2/s) with the opposite occurring during spring tide with larger Az during flood (10−1 m2/s) than ebb (10−2 m2/s). Lateral processes produced elevated near‐surface mixing decoupled from bottom‐generated turbulence at the end of flood and ebb tide during neap and spring. The secondary flows were driven by Coriolis, and these flows either enhanced (neap tide, end of flood) or maintained (spring tide, end of ebb) total shear through slack tides producing near‐surface to midwater column turbulence. These results are the first of their kind to show midwater column mixing from lateral circulation driven by Coriolis in a well‐mixed system, which vary from the lateral processes previously shown to destabilize water columns in estuaries more influenced by stratification.

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Section: Methodsmentioning

confidence: 99%

Intratidal and Fortnightly Variability of Vertical Mixing in a Macrotidal Estuary: The Gironde

2019

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“…When estimating R i , constraints were taken into consideration regarding the limiting value of Ri . Baumert and Peters [] demonstrated that turbulence does not exist when R i > 0.5 because TKE is converted to wave energy. Following the method of Ilicak et al .…”

Section: Methodsmentioning

confidence: 99%

Linkage between lateral circulation and near‐surface vertical mixing in a coastal plain estuary

Huguenard

Valle‐Levinson

et al. 2015

JGR Oceans

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Microstructure and current velocity measurements were collected at a cross-channel transect in the James River under spring and neap tidal conditions in May 2010 to study cross-estuary variations in vertical mixing. Results showed that near-surface mixing was related to lateral circulation during the ebb phase of a tidal cycle, and that the linkage was somewhat similar from neap to spring tides. During neap tides, near-surface mixing was generated by the straining of lateral density gradients influenced by the advection of fresh, riverine water on the right side (looking seaward) of the transect. Spring tide results revealed similar findings on the right side of the cross section. However, on the left side, the straining by velocity shears acted in concert with density straining. Weak along-estuary velocities over the left shoal were connected to faster velocities in the channel via a clockwise lateral circulation (looking seaward). These results provided evidence that in the absence of direct wind forcing, near-surface vertical mixing can occur from mechanisms uncoupled from bottom friction.

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“…The turbulent mixing layer in the lower part of the Earth's atmosphere has an important role in the vertical transport of moisture, small gas constituents, pollutants, and heat from the surface to the upper layers of the atmosphere. The turbulent mixing layer height is usually understood to be the thickness of the layer adjacent to the ground, in which in-coming substances become completely vertically distributed throughout the layer owing to convection or turbulence for an hour (Stull, 1988;Garratt, 1994;Bonin et al, 2018). Among other factors (Garratt, 1994), the mixing layer height strongly depends on the intensity of wind turbulence.…”

Section: Introductionmentioning

confidence: 99%

Estimation of the height of the turbulent mixing layer from data of Doppler lidar measurements using conical scanning by a probe beam

2021

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Abstract. A method is proposed for determining the height of the turbulent mixing layer on the basis of the vertical profiles of the dissipation rate of turbulent energy, which is estimated from lidar measurements of the radial wind velocity using conical scanning by a probe beam around the vertical axis. The accuracy of the proposed method is discussed in detail. It is shown that for the estimation of the mixing layer height (MLH) with the acceptable relative error not exceeding 20 %, the signal-to-noise ratio should be no less than −16 dB, when the relative error of lidar estimation of the dissipation rate does not exceed 30 %. The method was tested in a 6 d experiment in which the wind velocity turbulence was estimated in smog conditions due to forest fires in Siberia in summer 2019. The results of the experiment reveal that the relative error of determination of the MLH time series obtained by this method does not exceed 10 % in the period of turbulence development. The estimates of the turbulent mixing layer height by the proposed method are in a qualitative agreement with the MLH estimated from the distributions of the Richardson number in height and time obtained during the comparison experiment in spring 2020.

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Turbulence closure: turbulence, waves and the wave-turbulence transition – Part 1: Vanishing mean shear

Cited by 17 publications

References 44 publications

Intratidal and Fortnightly Variability of Vertical Mixing in a Macrotidal Estuary: The Gironde

Intratidal and Fortnightly Variability of Vertical Mixing in a Macrotidal Estuary: The Gironde

Linkage between lateral circulation and near‐surface vertical mixing in a coastal plain estuary

Estimation of the height of the turbulent mixing layer from data of Doppler lidar measurements using conical scanning by a probe beam

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