Similarity theory of diffusion and the observed vertical spread in the diabatic surface layer

1973 ◽  
Vol 3 (4) ◽  
pp. 405-415 ◽  
Author(s):  
F. H. Chaudhry ◽  
R. N. Meroney
Keyword(s):  
Surface Layer ◽  
Similarity Theory

scholarly journals Atmospheric surface layer characteristics of turbulence above the Pantanal wetland regarding the similarity theory

2008 ◽  
Vol 148 (6-7) ◽  
pp. 883-892 ◽  
Author(s):  
E.P. Marques Filho ◽  
L.D.A. Sá ◽  
H.A. Karam ◽  
R.C.S. Alvalá ◽  
A. Souza ◽  
...  
Keyword(s):  
Surface Layer ◽  
Atmospheric Surface Layer ◽  
Similarity Theory ◽  
Pantanal Wetland

scholarly journals Evaluating Monin-Obukhov Scaling in the Unstable Oceanic Surface Layer

2020 ◽  
Author(s):  
Zhihua Zheng ◽  
Ramsey R. Harcourt ◽  
Eric A. D’Asaro
Keyword(s):  
Surface Layer ◽  
Surface Waves ◽  
Scaling Laws ◽  
Similarity Theory ◽  
Vertical Mixing ◽  
Temperature Gradients ◽  
Langmuir Turbulence ◽  
Near Surface ◽  
Oceanic Surface ◽  
Using Data

AbstractMonin-Obukhov Similarity Theory (MOST) provides important scaling laws for flow properties in the surface layer of the atmosphere and has contributed to most of our understanding of the near-surface turbulence. The prediction of near-surface vertical mixing in most operational ocean models is largely built upon this theory. However, the validity of MOST in the upper ocean is questionable due to the demonstrated importance of surface waves in the region. Here we examine the validity of MOST in the statically unstable oceanic surface layer, using data collected from two open ocean sites with different wave conditions. The observed vertical temperature gradients are found to be about half of those predicted by MOST. We hypothesize this is attributable to either the breaking of surface waves, or Langmuir turbulence generated by the wave-current interaction. Existing turbulence closure models for surface wave breaking and for Langmuir turbulence are simplified to test these two hypotheses. Although both models predict reduced temperature gradients, the simplified Langmuir turbulence model matches observations more closely, when appropriately tuned.

Evaluating turbulent length scales from local MOST extension with different stability functions in first order closures for stably stratified boundary layer

2021 ◽  
Author(s):  
Andrey Debolskiy ◽  
Evgeny Mortikov ◽  
Andrey Glazunov ◽  
Christof Lüpkes
Keyword(s):  
Boundary Layer ◽  
Asymptotic Behavior ◽  
Surface Layer ◽  
Similarity Theory ◽  
Functional Dependence ◽  
Stability Parameter ◽  
Turbulent Length Scale ◽  
First Order ◽  
Stability Functions ◽  
The Stability

<p>According to the Monin-Obukhov similarity theory (MOST), in the stratified surface layer of the atmosphere, the mean vertical velocity and scalars gradients are related to the turbulent fluxes of these quantities and to the distance z from the surface in a universal manner. The stability parameter ζ=z/L, where L is the Obukhov turbulent length scale, is the only dimensionless parameter that determines the flux-gradient relationships. This imposes a dependency of the dimensionless velocity and buoyancy gradients on ζ in form of universal nondimensional stability functions for  the surface layer. Over the decades a number of them were proposed and derived mostly from extensive field campaigns of measurements in the ABL. The stability functions differ from each other by both open coefficients and functional dependence on  ζ.  They have a limited range of applicability, which is often extended by incorporating the assumption about their asymptotic behavior.</p><p>           A generalization of MOST by considering the dependence of the dimensionless gradients on the local stability parameter z/Λ  in the framework of first order closures allows the extension of  the universal stability functions from the surface layer to most of the ABL. However, because of applicability constraints, differences in the asymptotic behavior and in other implied assumptions, it is not immediately obvious, which set of stability functions will perform best. In this study we analyze a set of stability functions which are implemented in a uniform manner into a one-dimensional first-order closure.  The latter applies a turbulent mixing length with generalized local MOST scaling which fits to a surface schemes employing corresponding functions for consistency. We use two numerical experiment setups accompanied with LES data for validation which correspond to the weakly stable GABLES1 case and to LES simulations of the very stable ABL based on measurements at the Antarctic station DOME-C (van der Linden et al. 2019). We also focus on the sensitivity of the 1D model results to coarser grids with respect to both the used  surface flux schemes and  the ABL turbulence closures since their are meant to be used in climate models because of numerical efficiency.</p><p>Authors want to aknowledge partial funding by Russian Foundation for Basic Research (RFBR project N 20-05-00776), sensitivity analysis and closure development were performed with support  of Russian Science Foundation (RSF No 20-17-00190). Steven van der Linden for providing LES data of DOME-C based experiments.</p><p>References:</p><p>van der Linden S.J. et al. Large-Eddy Simulations of the Steady Wintertime Antarctic Boundary Layer // Boundary Layer Meteorology 173.2 (2019): 165-192.</p>

Understanding Aerosol Vertical Transport During Heavy Aerosol Pollution Episodes in the North China

2020 ◽  
Author(s):  
Renmin Yuan
Keyword(s):  
Surface Layer ◽  
Mass Flux ◽  
North China ◽  
Similarity Theory ◽  
Rural Site ◽  
Urban Site ◽  
The North ◽  
Aerosol Pollution ◽  
The Mean ◽  
Pollution Episodes

<p>Due to excessive anthropogenic emissions, heavy aerosol pollution episodes (HPEs) often occur during winter in the Beijing-Tianjin-Hebei (BTH) area of the North China Plain. Extensive observational studies have been carried out to understand the causes of HPEs; however, few measurements of vertical aerosol fluxes exist, despite them being the key to understanding vertical aerosol mixing, specifically during weak turbulence stages in HPEs. In the winter of 2016 and the spring of 2017 aerosol vertical mass fluxes were measured by combining large aperture scintillometer (LAS) observations, surface PM<sub>2.5</sub> and PM<sub>10</sub> mass concentrations, and meteorological observations, including temperature, relative humidity (RH), and visibility, at a rural site in Gucheng (GC), Hebei Province, and an urban site at the Chinese Academy of Meteorological Sciences (CAMS) in Beijing located 100 km to the northeast. These are based on the light propagation theory and surface-layer similarity theory. The near-ground aerosol mass flux was generally lower in winter than in spring and weaker in rural GC than in urban Beijing. This finding provides direct observational evidence for a weakened turbulence intensity and low vertical aerosol fluxes in winter and polluted areas such as GC. The HPEs included a transport stage (TS), an accumulative stage (AS), and a removal stage (RS). During the HPEs from 25 January 2017 to January 31, 2017, in Beijing, the mean mass flux decreased by 51% from 0.0049 mg m<sup>-2</sup>s<sup>-1</sup> in RSs to 0.0024 mg m<sup>-2</sup>s<sup>-1</sup> in the TSs. During the ASs, the mean mass flux decreased further to 0.00087 mg m<sup>-2</sup>s<sup>-1</sup>, accounting for approximately 1/3 of the flux in the TSs. A similar reduction from the TSs to ASs was observed in the HPE from 16 December 2016 to 22 December 2016 in GC. It can be seen that from the TS to the AS, the aerosol vertical turbulent flux decreased, but the aerosol particle concentration within surface layer increased, and it is inferred that in addition to the contribution of regional transport from upwind areas during the TS, suppression of vertical turbulence mixing confining aerosols to a shallow boundary layer increased accumulation.</p>

scholarly journals Random Errors in Turbulence Measurements in the Atmospheric Surface Layer: Implications for Monin–Obukhov Similarity Theory

2012 ◽  
Vol 69 (12) ◽  
pp. 3700-3714 ◽  
Author(s):  
Scott T. Salesky ◽  
Marcelo Chamecki
Keyword(s):  
Surface Layer ◽  
Diurnal Variation ◽  
Atmospheric Surface Layer ◽  
Friction Velocity ◽  
Similarity Theory ◽  
Statistical Hypothesis ◽  
Random Errors ◽  
Propagation Analysis ◽  
Error Propagation Analysis ◽  
First Time

Abstract An error propagation analysis is conducted to estimate random errors in the friction velocity u* and the Monin–Obukhov similarity theory (MOST) stability variable z/L from estimated random errors in the turbulent fluxes. Errors in the dimensionless mean wind shear φm and mean temperature gradient φh are also estimated. To the authors’ knowledge, this is the first time that errors in calculated values of z/L, φm, and φh have been systematically analyzed. Random errors in z/L are found to be large for unstable conditions, reaching values of 40% or greater. It is shown through statistical hypothesis tests that random errors cannot explain departures of calculated values of φm and φh from theory. The deviation of calculated values of φm from empirical curves is found to have a strong diurnal variation that increases with height; deviations of φh from theory are not found to have clear diurnal variation. These results support the findings of previous studies, which have suggested that additional dimensionless parameters representing additional physical processes need to be included in the set of governing parameters for surface layer similarity. Implications for atmospheric surface layer turbulence are also discussed.

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