2018-2019 measurement data for the characteristics of the Monin-Obukhov similarity theory in the mountain boundary layer of the atmosphere

2021 ◽  
Author(s):  
Victor V. Nosov ◽  
Vladimir P. Lukin ◽  
Eugene V. Nosov ◽  
Andrey V. Torgaev
Keyword(s):  
Boundary Layer ◽  
Similarity Theory ◽  
Measurement Data

Evaluation of Boundary Layer Similarity Theory for Stable Conditions in CASES-99

2007 ◽  
Vol 135 (10) ◽  
pp. 3474-3483 ◽  
Author(s):  
Kyung-Ja Ha ◽  
Yu-Kyung Hyun ◽  
Hyun-Mi Oh ◽  
Kyung-Eak Kim ◽  
Larry Mahrt
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Similarity Theory ◽  
Unknown Origin ◽  
Strong Stability ◽  
Surface Exchange ◽  
Stability Functions ◽  
Stable Conditions ◽  
Mean Wind Speed ◽  
Strong Winds

Abstract The Monin–Obukhov similarity theory and a generalized formulation of the mixing length for the stable boundary layer are evaluated using the Cooperative Atmosphere–Surface Exchange Study-1999 (CASES-99) data. The large-scale wind forcing is classified into weak, intermediate, and strong winds. Although the stability parameter, z/L, is inversely dependent on the mean wind speed, the speed of the large-scale flow includes independent influences on the flux–gradient relationship. The dimensionless mean wind shear is found to obey existing stability functions when z/L is less than unity, particularly for the strong and intermediate wind classes. For weak mean winds and/or strong stability (z/L > 1), this similarity theory breaks down. Deviations from similarity theory are examined in terms of intermittency. A case study of a weak-wind night indicates important modulation of the turbulence flux by mesoscale motions of unknown origin.

scholarly journals A New Value of the von Kármán Constant: Implications and Implementation

2009 ◽  
Vol 48 (5) ◽  
pp. 923-944 ◽  
Author(s):  
Edgar L. Andreas
Keyword(s):  
Boundary Layer ◽  
Similarity Theory ◽  
Stable Stratification ◽  
Transfer Coefficients ◽  
Obukhov Length ◽  
Von Karman ◽  
Roughness Lengths ◽  
Experimental Values ◽  
Definition Of ◽  
Von Kármán

Abstract The von Kármán constant k occurs throughout the mathematics that describe the atmospheric boundary layer. In particular, because k was originally included in the definition of the Obukhov length, its value has both explicit and implicit effects on the functions of Monin–Obukhov similarity theory. Although credible experimental evidence has appeared sporadically that the von Kármán constant is different than the canonical value of 0.40, the mathematics of boundary layer meteorology still retain k = 0.40—probably because the task of revising all of this math to implement a new value of k is so daunting. This study therefore outlines how to make these revisions in the nondimensional flux–gradient relations; in variance, covariance, and dissipation functions; and in structure parameters of Monin–Obukhov similarity theory. It also demonstrates how measured values of the drag coefficient (CD), the transfer coefficients for sensible (CH) and latent (CE) heat, and the roughness lengths for wind speed (z0), temperature (zT), and humidity (zQ) must be modified for a new value of the von Kármán constant. For the range of credible experimental values for k, 0.35–0.436, revised values of CD, CH, CE, z0, zT, and zQ could be quite different from values obtained assuming k = 0.40, especially if the original measurements were made in stable stratification. However, for the value of k recommended here, 0.39, no revisions to the transfer coefficients and roughness lengths should be necessary. Henceforth, use the original measured values of transfer coefficients and roughness lengths but do use similarity functions modified to reflect k = 0.39.

scholarly journals The North Atlantic Marine Boundary Layer Experiment(NAMBLEX). Overview of the campaign held at Mace Head, Ireland, in summer 2002

2006 ◽  
Vol 6 (8) ◽  
pp. 2241-2272 ◽  
Author(s):  
D. E. Heard ◽  
K. A. Read ◽  
J. Methven ◽  
S. Al-Haider ◽  
W. J. Bloss ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
Numerical Models ◽  
Measurement Data ◽  
Air Mass ◽  
The North ◽  
Trace Species ◽  
Wide Range ◽  
The North Atlantic

Abstract. The North Atlantic Marine Boundary Layer Experiment (NAMBLEX), involving over 50 scientists from 12 institutions, took place at Mace Head, Ireland (53.32° N, 9.90° W), between 23 July and 4 September 2002. A wide range of state-of-the-art instrumentation enabled detailed measurements of the boundary layer structure and atmospheric composition in the gas and aerosol phase to be made, providing one of the most comprehensive in situ studies of the marine boundary layer to date. This overview paper describes the aims of the NAMBLEX project in the context of previous field campaigns in the Marine Boundary Layer (MBL), the overall layout of the site, a summary of the instrumentation deployed, the temporal coverage of the measurement data, and the numerical models used to interpret the field data. Measurements of some trace species were made for the first time during the campaign, which was characterised by predominantly clean air of marine origin, but more polluted air with higher levels of NOx originating from continental regions was also experienced. This paper provides a summary of the meteorological measurements and Planetary Boundary Layer (PBL) structure measurements, presents time series of some of the longer-lived trace species (O3, CO, H2, DMS, CH4, NMHC, NOx, NOy, PAN) and summarises measurements of other species that are described in more detail in other papers within this special issue, namely oxygenated VOCs, HCHO, peroxides, organo-halogenated species, a range of shorter lived halogen species (I2, OIO, IO, BrO), NO3 radicals, photolysis frequencies, the free radicals OH, HO2 and (HO2+Σ RO2), as well as a summary of the aerosol measurements. NAMBLEX was supported by measurements made in the vicinity of Mace Head using the NERC Dornier-228 aircraft. Using ECMWF wind-fields, calculations were made of the air-mass trajectories arriving at Mace Head during NAMBLEX, and were analysed together with both meteorological and trace-gas measurements. In this paper a chemical climatology for the duration of the campaign is presented to interpret the distribution of air-mass origins and emission sources, and to provide a convenient framework of air-mass classification that is used by other papers in this issue for the interpretation of observed variability in levels of trace gases and aerosols.

Detailed Analysis of Experimental Investigations on Boundary Layer Transition in Wake Disturbed Flow

2006 ◽  
Author(s):  
Andrea Cattanei ◽  
Pietro Zunino ◽  
Thomas Schro¨der ◽  
Bernd Stoffel ◽  
Berthold Matyschok
Keyword(s):  
Boundary Layer ◽  
Measurement Data ◽  
Boundary Layer Transition ◽  
Data Evaluation ◽  
Experimental Investigations ◽  
Layer Transition ◽  
Disturbed Flow ◽  
Time Space ◽  
Separation Bubbles ◽  
Hot Film

In the framework of a co-operation between the University of Genoa and the Darmstadt University of Technology measurement data of a former investigation at Darmstadt, comprising measurements with surface-mounted hot-film sensors on the boundary layer transition in wake disturbed flow, were transferred to Genoa, then re-evaluated and in great detail analyzed, much further than the original data evaluation. In these experimental investigations at Darmstadt, the boundary layer transition with and without transitional separation bubbles was studied on a circular cylinder in cross flow. The comparison of hot-wire traverses with the surface-mounted hot-film distributions clearly indicated that the surface-mounted hot-film technique is a very suitable measurement technique to obtain reliable information on transition and separation phenomena with both high spatial and temporal resolution. The new data evaluation techniques applied to these data at Genoa further enhanced the insight into the details of the boundary layer transition and separation process. The surface-mounted hot-film data were evaluated by means of time-space diagrams for the first three statistical moments (mean, RMS and skewness), with which the origin and the extent of unsteady separation bubbles clearly could be seen. The results obtained from these data analyses on the one hand yield a considerable enhancement of the understanding of the periodically unsteady boundary layer transition process and on the other hand they form the basis for the application of surface-mounted hot-film sensors in more complex flow situations like e.g. in cold flow multistage turbine or compressor test rigs or even in the hostile environment of real aero engine compressors or turbines.

scholarly journals Importance of Using Observations of Mixing Depths in order to Avoid Large Prediction Errors by a Transport and Dispersion Model

2009 ◽  
Vol 26 (1) ◽  
pp. 22-32 ◽  
Author(s):  
J. M. White ◽  
J. F. Bowers ◽  
S. R. Hanna ◽  
J. K. Lundquist
Keyword(s):  
Boundary Layer ◽  
Atmospheric Transport ◽  
Similarity Theory ◽  
Dispersion Model ◽  
Heat Fluxes ◽  
Synoptic Situation ◽  
Prediction Errors ◽  
Sensible Heat ◽  
Mixing Depth ◽  
Near Surface

Abstract The mixing depth of the boundary layer is an input to most atmospheric transport and dispersion (ATD) models, which obtain mixing depths in one of four ways: 1) observations by radiosondes, sodars, or other devices; 2) simulations by regional or mesoscale meteorological models; 3) parameterizations based on boundary layer similarity theory; or 4) climatological averages. This paper describes a situation during a field experiment when exceptionally low mixing depths persisted in the morning and led to relatively high observed tracer concentrations. The low mixing depths were caused by synoptic effects associated with a nearby stationary front and the outflow from a mesoscale thunderstorm complex located 20–50 km away. For the same time period, the ATD model-parameterized mixing depth was a factor of 5–10 higher, leading to predicted concentrations that were less than the observations by a factor of 5–10. The synoptic situation is described and local radiosonde and radar observations of mixing depth are presented, including comparisons with other more typical days. Time series of local observations of near-surface sensible heat fluxes are also plotted to demonstrate the suppression of turbulence by negative sensible heat fluxes during the period in question.

scholarly journals The Critical Richardson Number and Limits of Applicability of Local Similarity Theory in the Stable Boundary Layer

2012 ◽  
Vol 147 (1) ◽  
pp. 51-82 ◽  
Author(s):  
Andrey A. Grachev ◽  
Edgar L Andreas ◽  
Christopher W. Fairall ◽  
Peter S. Guest ◽  
P. Ola G. Persson
Keyword(s):  
Boundary Layer ◽  
Stable Boundary Layer ◽  
Richardson Number ◽  
Similarity Theory ◽  
Local Similarity ◽  
Stable Boundary ◽  
Critical Richardson Number ◽  
Local Similarity Theory

scholarly journals Turbulence in a coastal environment: the case of Vindeby

2021 ◽  
Author(s):  
Rieska Mawarni Putri ◽  
Etienne Cheynet ◽  
Charlotte Obhrai ◽  
Jasna Bogunovic Jakobsen
Keyword(s):  
Wind Turbines ◽  
Wind Farm ◽  
Similarity Theory ◽  
Spectral Characteristics ◽  
Measurement Data ◽  
Offshore Wind ◽  
Wind Component ◽  
Neutral Atmosphere ◽  
Strong Wind ◽  
Offshore Wind Turbines

Abstract. Turbulence spectral characteristics for various atmospheric stratifications are studied using the observations from an offshore mast at Vindeby wind farm. Measurement data at 6 m, 18 m and 45 m above the mean sea level are considered. At the lowest height, the normalized power spectral densities of the velocity components show deviations from Monin-Obukhov similarity theory (MOST). A significant co-coherence at the wave spectral peak frequency between the vertical velocity component and the velocity of the sea surface is observed, but only when the significant wave heights exceed 0.9 m. The turbulence spectra at 18 m generally follow MOST and are consistent with the empirical spectra established on the FINO1 offshore platform from an earlier study. The data at 45 m is associated with a high-frequency measurement noise which limits its analysis to strong wind conditions only. The estimated co-coherence of the along-wind component under near-neutral atmosphere matches remarkably well with those at FINO1. The turbulence characteristics estimated from the present dataset are valuable to better understand the structure of turbulence in the marine atmospheric boundary layer and are relevant for load estimations of offshore wind turbines. Yet, a direct application of the results to other offshore or coastal sites should be exercised with caution, since the dataset is collected in shallow waters and at heights lower than the hub height of the current and the future state-of-the-art offshore wind turbines.

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