Molecular dissipation of turbulent fluctuations in the convective mixed layer part I: Height variations of dissipation rates

1983 ◽  
Vol 27 (2) ◽  
pp. 141-162 ◽  
Author(s):  
B. Guillemet ◽  
H. Isaka ◽  
P. Mascart
Keyword(s):  
Mixed Layer ◽  
Turbulent Fluctuations ◽  
Dissipation Rates ◽  
Convective Mixed Layer

An Observational Study of Wind Profiles in the Baroclinic Convective Mixed Layer

1999 ◽  
Vol 90 (1) ◽  
pp. 47-82 ◽  
Author(s):  
Margaret a. Lemone ◽  
Mingyu Zhou ◽  
Chin-Hoh Moeng ◽  
Donald H. Lenschow ◽  
L. Jay Miller ◽  
...  
Keyword(s):  
Observational Study ◽  
Mixed Layer ◽  
Convective Mixed Layer ◽  
Wind Profiles

Turbulence in an oceanic convective mixed layer

Nature ◽  
1984 ◽  
Vol 310 (5975) ◽  
pp. 282-285 ◽  
Author(s):  
Thomas J. Shay ◽  
Michael C. Gregg
Keyword(s):  
Mixed Layer ◽  
Convective Mixed Layer

scholarly journals Turbulence in an oceanic convective mixed layer—Corrigendum

Nature ◽  
1984 ◽  
Vol 311 (5981) ◽  
pp. 84-84 ◽  
Author(s):  
T. J. Shay ◽  
M. C. Greg
Keyword(s):  
Mixed Layer ◽  
Convective Mixed Layer

scholarly journals Investigating microscale patchiness of motile microbes driven by the interaction of turbulence and gyrotaxis in a 3D simulated convective mixed layer.

2021 ◽  
Author(s):  
Alexander Christensen ◽  
Matthew Piggott ◽  
Erik van Sebille ◽  
Maarten van Reeuwijk ◽  
Samraat Pawar
Keyword(s):  
Mixed Layer ◽  
Fluid Model ◽  
Spatial Dynamics ◽  
Critical Factor ◽  
Trophic Levels ◽  
Small Scale ◽  
Swimming Velocity ◽  
Primary Role ◽  
Fluid Surface ◽  
Convective Mixed Layer

Abstract Microbes play a primary role in aquatic ecosystems and biogeochemical cycles. Spatial patchiness is a critical factor underlying these activities, influencing biological productivity, nutrient cycling and dynamics across trophic levels. Incorporating spatial dynamics into microbial models is a long-standing challenge, particularly where small-scale turbulence is involved. Here, we combine a fully 3D direct numerical simulation of convective mixed layer turbulence, with an individual-based microbial model to test the key hypothesis that the coupling of gyrotactic motility and turbulence drives intense microscale patchiness. The fluid model simulates turbulent convection caused by heat loss through the fluid surface, for example during the night, during autumnal or winter cooling or during a cold-air outbreak. We find that under such conditions, turbulence-driven patchiness is depth-structured and requires high motility: Near the fluid surface, intense convective turbulence overpowers motility, homogenising motile and non-motile microbes approximately equally. At greater depth, in conditions analogous to a thermocline, highly motile microbes can be over twice as patch-concentrated as non-motile microbes, and can substantially amplify their swimming velocity by efficiently exploiting fast-moving packets of fluid. Our results substantiate the predictions of earlier studies, and demonstrate that turbulence-driven patchiness is not a ubiquitous consequence of motility but rather a delicate balance of motility and turbulent intensity.

Horizontal turbulent diffusion in a convective mixed layer

2014 ◽  
Vol 758 ◽  
pp. 553-564 ◽  
Author(s):  
Junshi Ito ◽  
Hiroshi Niino ◽  
Mikio Nakanishi
Keyword(s):  
Scalar Field ◽  
Mixed Layer ◽  
Turbulent Diffusion ◽  
Passive Scalar ◽  
Rate Of Change ◽  
Horizontal Gradient ◽  
Scalar Flux ◽  
Turbulent Diffusion Coefficient ◽  
Convective Mixed Layer ◽  
Convergence Zones

AbstractA large eddy simulation (LES) is used to estimate a reliable horizontal turbulent diffusion coefficient, $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}K_{{h}}$, in a convective mixed layer (CML). The introduction of a passive scalar field with a fixed horizontal gradient at a given time enables $K_{{h}}$ estimation as a function of height, based on the simulated turbulent horizontal scalar flux. Here $K_{{h}}$ is found to be of the order of $100\ {\mathrm{m}}^2\ {\mathrm{s}}^{-1}$ for a typical terrestrial atmospheric CML. It is shown to scale by the product of the CML convective velocity, $w_{*}$, and its depth, $h$. Here $K_{{h}}$ is characterized by a vertical profile in the CML: it is large near both the bottom and top of the CML, where horizontal flows associated with convection are large. The equation pertaining to the temporal rate of change of a horizontal scalar flux suggests that $K_{{h}}$ is determined by a balance between production and pressure correlation at a fully developed stage. Pressure correlation near the bottom of the CML is localized in convergence zones near the boundaries of convective cells and becomes large within an eddy turnover time, $h/w_{*}$, after the introduction of the passive scalar field.

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