On the theoretical relationship between the Monin-Obukhov stability parameter and the bulk Richardson number

1993 ◽  
Vol 16 (1) ◽  
pp. 1-7 ◽  
Author(s):  
N. M. Zoumakis ◽  
A. G. Kelessis
Keyword(s):  
Richardson Number ◽  
Stability Parameter ◽  
Bulk Richardson Number ◽  
Theoretical Relationship

scholarly journals On the computation of planetary boundary-layer height using the bulk Richardson number method

2014 ◽  
Vol 7 (6) ◽  
pp. 2599-2611 ◽  
Author(s):  
Y. Zhang ◽  
Z. Gao ◽  
D. Li ◽  
Y. Li ◽  
N. Zhang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Boundary Layers ◽  
Planetary Boundary Layer ◽  
Richardson Number ◽  
Potential Temperature ◽  
Bulk Richardson Number ◽  
Stable Boundary Layers ◽  
Stable Boundary ◽  
Field Campaigns ◽  
Weakly Stable

Abstract. Experimental data from four field campaigns are used to explore the variability of the bulk Richardson number of the entire planetary boundary layer (PBL), Ribc, which is a key parameter for calculating the PBL height (PBLH) in numerical weather and climate models with the bulk Richardson number method. First, the PBLHs of three different thermally stratified boundary layers (i.e., strongly stable boundary layers, weakly stable boundary layers, and unstable boundary layers) from the four field campaigns are determined using the turbulence method, the potential temperature gradient method, the low-level jet method, and the modified parcel method. Then for each type of boundary layer, an optimal Ribc is obtained through linear fitting and statistical error minimization methods so that the bulk Richardson method with this optimal Ribc yields similar estimates of PBLHs as the methods mentioned above. We find that the optimal Ribc increases as the PBL becomes more unstable: 0.24 for strongly stable boundary layers, 0.31 for weakly stable boundary layers, and 0.39 for unstable boundary layers. Compared with previous schemes that use a single value of Ribc in calculating the PBLH for all types of boundary layers, the new values of Ribc proposed by this study yield more accurate estimates of PBLHs.

Evaluation of methods for estimating atmospheric stability at two coastal sites

2018 ◽  
Vol 42 (6) ◽  
pp. 561-575 ◽  
Author(s):  
Lars Morten Bardal ◽  
Anja Eide Onstad ◽  
Lars Roar Sætran ◽  
John Amund Lund
Keyword(s):  
Surface Layer ◽  
Richardson Number ◽  
Atmospheric Stability ◽  
Stability Conditions ◽  
Bulk Richardson Number ◽  
Wind Speed Profile ◽  
Flux Measurements ◽  
Vertical Wind Speed ◽  
Stability Measurements ◽  
Evaluation Of Methods

Understanding the atmospheric stability conditions is important in order to obtain accurate estimates of the vertical wind speed profile. This work compares and evaluates common methods for estimation of atmospheric stability using standard meteorological mast observations. Atmospheric stability distributions from three different met-masts located at two coastal sites are calculated and compared. The atmospheric stability parameter, L is estimated using the bulk Richardson number, the surface-layer Richardson number, and calculated directly from eddy covariance flux measurements. The resulting distributions vary depending on which method is used. The atmospheric stability measurements from two masts located 3 km apart in similar terrain are compared directly. The highest correlation is found for the surface-layer Richardson number method. This method it also less sensitive to variation of measurement heights than the bulk Richardson number method.

Large Eddy Simulations of a Stratified Shear Layer

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Hieu T. Pham ◽  
Sutanu Sarkar
Keyword(s):  
Reynolds Number ◽  
Shear Layer ◽  
Richardson Number ◽  
Scalar Dissipation ◽  
Momentum Thickness ◽  
Bulk Richardson Number ◽  
Scalar Flux ◽  
Linear Evolution ◽  
Eddy Simulation ◽  
Large Eddy

The performance of the large eddy simulation (LES) approach in predicting the evolution of a shear layer in the presence of stratification is evaluated. The LES uses a dynamic procedure to compute subgrid model coefficients based on filtered velocity and density fields. Two simulations at different Reynolds numbers are simulated on the same computational grid. The fine LES simulated at a low Reynolds number produces excellent agreement with direct numerical simulations (DNS): the linear evolution of momentum thickness and bulk Richardson number followed by an asymptotic approach to constant values is correctly represented and the evolution of the integrated turbulent kinetic energy budget is well captured. The model coefficients computed from the velocity and the density fields are similar and have a value in range of 0.01-0.02. The coarse LES simulated at a higher Reynolds number Re = 50,000 shows acceptable results in terms of the bulk characteristics of the shear layer, such as momentum thickness and bulk Richardson number. Analysis of the turbulent budgets shows that, while the subgrid stress is able to remove sufficient energy from the resolved velocity fields, the subgrid scalar flux and thereby the subgrid scalar dissipation are underestimated by the model.

Sign in / Sign up

Export Citation Format

Share Document