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Title: Scaling the Mixing Efficiency of Sediment‐Stratified Turbulence

The flux Richardson numberRf, also called the mixing efficiency of stratified turbulence, is important in determining geophysical flow phenomena such as ocean circulation and air‐sea transports. MeasuringRfin the field is usually difficult, thus parameterization ofRfbased on readily observed properties is essential. Here, estimates ofRfin a strongly turbulent, sediment‐stratified estuarine flow are obtained from measurements of covariance‐derived turbulent buoyancy fluxes (B) and spectrally fitted values of the dissipation rate of turbulent kinetic energy (ε). We test scalings forRfin terms of the buoyancy Reynolds number (Reb), the gradient Richardson number (Ri), and turbulent Froude number (Frt). Neither theReb‐based nor theRi‐based scheme is able to describe the observed variations inRf, but theFrt‐based parameterization works well. These findings support further use of theFrt‐ based parameterization in turbulent oceanic and estuarine environments.

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DOI PREFIX: 10.1029
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Journal Name:
Geophysical Research Letters
Medium: X
Sponsoring Org:
National Science Foundation
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