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A Parameterization Of Intermittent Turbulence In The Stable Boundary Layer
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Book Synopsis A Parameterization of Intermittent Turbulence in the Stable Boundary Layer by :
Download or read book A Parameterization of Intermittent Turbulence in the Stable Boundary Layer written by and published by . This book was released on 2003 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: The atmospheric boundary layer is of special interest due to its direct impact and interaction with the surface of the earth where most human activity occurs. The daytime boundary layer is dominated by convective turbulence, and thus is modeled easily. However, sources of turbulence at night are multiple and varied, making the flow more difficult to predict. And yet it is important to predict nocturnal dynamics because of its influences on aviation, the dispersion of pollutants, and fog formation.
Book Synopsis An Examination of Structure and Parameterization of Turbulence in the Stably-stratified Atmospheric Boundary Layer by : Paul Harold Ruscher
Download or read book An Examination of Structure and Parameterization of Turbulence in the Stably-stratified Atmospheric Boundary Layer written by Paul Harold Ruscher and published by . This book was released on 1987 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: The very stable boundary layer is a region of the atmosphere typified by large vertical gradients of temperature and momentum. Analysis of very stable atmospheric flows is complicated by the presence of nonlinear interactions among gravity waves, shear-driven overturning circulations, two-dimensional vortical modes and intermittent turbulence in various stages of development. This study examines the horizontal structure of a very stable atmospheric boundary layer, using data obtained primarily from terrain-following aircraft flights over central Oklahoma. Several diagnostic procedures are applied to the aircraft data, including classical and rotary spectral analysis, principal component analysis, and structure functions. Coherent structures with sharp boundaries are examined with a new conditional sampling technique which requires little a priori specification of sampling criteria. Because the flows involve sharp boundaries, spectral techniques do not provide as much useful information as other more localized procedures. The edges of the coherent structures are regions of significant vertical heat transport, a feature not often emphasized in studies of gravity waves and vortical modes in the stable boundary layer. The presence of significant turbulence even for large stability has implications for modelling of the very stable boundary layer. Forecasts of minimum temperature, boundary layer height, inversion characteristics, and pollutant dispersal are all significantly affected by turbulent mixing. Many models of the stable boundary layer artificially arrest the mixing under stable conditions, resulting in, for example, overestimates of nocturnal cooling. A new parameterization of the stable boundary layer is studied here by incorporating it into an existing model of the planetary boundary layer. The model is then run with one-dimensional sensitivity tests for an idealized atmosphere and with data from Wangara day 33. A simulation over snow cover is also examined. The tests substantiate the role of vertical mixing in ameliorating nocturnal cooling. An additional improvement is a more realistic boundary layer height for moderate wind speeds.
Book Synopsis Surface Layer Flux Sources and Parameterization Failure in Stable Conditions from CASES-99 Data Analysis: Impacts of Intermittent Turbulence Its Sources and a Proposed Solution by :
Download or read book Surface Layer Flux Sources and Parameterization Failure in Stable Conditions from CASES-99 Data Analysis: Impacts of Intermittent Turbulence Its Sources and a Proposed Solution written by and published by . This book was released on 2003 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work is comprised of a comprehensive investigation of the evolution and stability of and the turbulent mixing and fluxes within, the stable nocturnal boundary layer (NBL) using the Cooperative Atmosphere-Surface Exchange Study (CASES) instrumented site in south central Kansas and the greatly enhanced in-situ instrumentation to be deployed during CASES-99. It was motivated by the need to establish the role of the NBL and phenomena within the NBL in surface and boundary layer heat and momentum fluxes. We have used the correlative high-resolution measurements of turbulence generation and mixing during CASE S-99 to 1) understand the dynamics and characteristics of turbulence in the NBL, 2) identify the dominant sources of turbulence, and 3) quantify the heat and momentum fluxes, for the improvement of existing parameterization. During the 2 year period of the contract we completed extensive observational analyses and quantification of NBL flux, including data analysis from the Intensive Observational Periods (IOPs). Our research has been extensive and significantly progressed the atmospheric science field's knowledge of the processes contributing to turbulent mixing and transport in the stable NBL and has specifically enabled their more quantitative parameterization, with direct future impacts on the improved numerical simulation of severe dispersion periods.
Book Synopsis Intermittent Turbulence in the Very Stable Ekman Layer by :
Download or read book Intermittent Turbulence in the Very Stable Ekman Layer written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: INTERMITTENT TURBULENCE IN THE VERY STABLE EKMAN LAYER This study describes a Direct Numerical Simulation (DNS) of a very stable Ekman layer in which a constant downward heat flux is applied at the lower boundary, thus cooling the fluid above. Numerical experiments were performed in which the strength of the imposed heat flux was varied. For downward heat fluxes above a certain critical value the turbulence becomes intermittent and, as the heat flux increases beyond this value, the flow tends to relaminarize because of the very strong ambient stratification. We adopt Mahrt?s (1999) definition of the very stable boundary layer as a boundary layer in which intermittent, rather than continuous turbulence, is observed. Numerical experiments were used to test various hypothesis of where in?stability parameter space? the very stable boundary layer is found. These experiments support the findings of Howell and Sun (1999) that the boundary layer will exhibit intermittency and therefore be categorized as?very stable?, when the stability parameter, z/L, exceeds unity. Another marker for the very stable boundary layer, Derbyshire?s (1990) maximum heat flux criterion, was also examined. Using a case study drawn from the simulations where turbulence intermittency was observed, the mechanism that causes the intermittence was investigated. It was found that patchy turbulence originates from a vigorous inflectional, Ekman-like instability -- a roll cell -- that lifts colder air over warmer air. The resulting convective instability causes an intense burst of turbulence. This turbulence is short-lived because the lifting motion of the roll cell, as well as the roll cell itself, is partially destroyed after the patchy turbulence is generated. Examples of intermittent turbulence obtained from the simulations appear to be consistent with observations of intermittency even though the Reynolds number of the DNS is relatively low (400).
Book Synopsis Intermittent Turbulence and Oscillations in the Stable Boundary Layer Over Land by : Bas van de Wiel
Download or read book Intermittent Turbulence and Oscillations in the Stable Boundary Layer Over Land written by Bas van de Wiel and published by . This book was released on 2002 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Atmospheric Boundary Layer by : J. R. Garratt
Download or read book The Atmospheric Boundary Layer written by J. R. Garratt and published by Cambridge University Press. This book was released on 1994-04-21 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book gives a comprehensive and lucid account of the science of the atmospheric boundary layer (ABL). There is an emphasis on the application of the ABL to numerical modelling of the climate. The book comprises nine chapters, several appendices (data tables, information sources, physical constants) and an extensive reference list. Chapter 1 serves as an introduction, with chapters 2 and 3 dealing with the development of mean and turbulence equations, and the many scaling laws and theories that are the cornerstone of any serious ABL treatment. Modelling of the ABL is crucially dependent for its realism on the surface boundary conditions, and chapters 4 and 5 deal with aerodynamic and energy considerations, with attention to both dry and wet land surfaces and sea. The structure of the clear-sky, thermally stratified ABL is treated in chapter 6, including the convective and stable cases over homogeneous land, the marine ABL and the internal boundary layer at the coastline. Chapter 7 then extends the discussion to the cloudy ABL. This is seen as particularly relevant, since the extensive stratocumulus regions over the subtropical oceans and stratus regions over the Arctic are now identified as key players in the climate system. Finally, chapters 8 and 9 bring much of the book's material together in a discussion of appropriate ABL and surface parameterization schemes in general circulation models of the atmosphere that are being used for climate simulation.
Book Synopsis Improved Parameterization of Stably Stratified Boundary Layer Turbulence in Atmospheric Models by :
Download or read book Improved Parameterization of Stably Stratified Boundary Layer Turbulence in Atmospheric Models written by and published by . This book was released on 2005 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the course of the project, our research has spanned over several areas encompassing theoretical, numerical and phenomenological aspects of stably stratified atmospheric boundary layers (SBLs). We have laid a solid foundation for studying stably stratified turbulence in the framework of a Quasi-Normal Scale Elimination theory (QNSE) developed by us. We consider the QNSE theory as a major breakthrough in this field. Being maximally proximate to the first principles, the theory penetrates very deeply into the physics of anisotropic turbulence and turbulence-wave interaction yet its calculations can be carried out analytically almost to the final results. We have performed initial analytical exploration of the new theory and implemented it in Reynolds-averaged, Navier-Stokes (RANS) models whose predictions agree well with data collected in BASE and SHEBA campaigns. In addition, we investigated non-local features of stable planetary boundary layers (PBLs) caused by semi-organized structures overlooked in traditional boundary-layer meteorology and in PBL schemes currently used in atmospheric models. Theoretical developments focused on basic length scales characterizing semi-organized structures and corresponding revision of classical similarity theory, PBL depth equations, and bulk resistance and heat/mass transfers laws.
Book Synopsis Overview and First Results from Project STABLE (STAble Boundary Layer Experiment). by :
Download or read book Overview and First Results from Project STABLE (STAble Boundary Layer Experiment). written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The STABLE project (STAble Boundary Layer Experiment) is a multiyear research effort conceived in 1984 by the Savannah River Laboratory (SRL) and planned by several research groups to study turbulence and diffusion in the stable boundary layer (SBL). The program was jointly planned by Department of Energy (DOE) affiliated laboratories and universities including SRL, Atmospheric Turbulence and Diffusion Division (ATDD) of the National Oceanic and Atmospheric Administration (NOAA), Argonne National Laboratory (ANL), North Carolina State University (NCSU), and The Pennsylvania State University. STABLE's goals are to determine the spatial and temporal distribution of turbulent events during the nighttime, to determine the validity of present models and theories in describing the structure and evolution of the SBL, to determine the role of waves and intermittent turbulence in dispersing chemicals, and to determine better parameterization for describing the mean state and intermittent events in the SBL. By taking advantage of special facility, the program seeks to economize effort and cost. 1 ref., 7 figs.
Book Synopsis Practical Meteorology by : Roland Stull
Download or read book Practical Meteorology written by Roland Stull and published by Sundog Publishing, LLC. This book was released on 2018 with total page 942 pages. Available in PDF, EPUB and Kindle. Book excerpt: A quantitative introduction to atmospheric science for students and professionals who want to understand and apply basic meteorological concepts but who are not ready for calculus.
Book Synopsis Boundary Layer Parameterization for a Global Spectral Model by : Larry Mahrt
Download or read book Boundary Layer Parameterization for a Global Spectral Model written by Larry Mahrt and published by . This book was released on 1987 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: Much of the work has concentrated on interactions between the soil model and the model of the atmospheric boundary layer and the behavior of the boundary-layer package within the Air Force Global Spectral Model. Such studies have underscored the importance of the formulation of surface properties and transport within the underlying soil. Work during the contract period also focussed on elimination of several inadequacies of boundary-layer modelling. The inclusion of the statistical impact of subgrid variations of surface properties leads to a surface exchange coefficient which varies more smoothly with stability and does not decrease as rapidly with very stable conditions. Such modifications reduce the nocturnal cooling which is usually overestimated in boundary-layer models. Other improvements of the boundary-layer model in stable conditions have resulted from increasing the critical Richardson number in the boundary-layer depth formulation and adopting the Kondo formulation for the eddy diffusivity. The development of a formulation for boundary-layer cumulus has allowed inclusion of cloud-induced drying. Although this formulation leads to significant improvement of the boundary-layer predictions in cloudy situations, the general problem is far from solved. Keywords: Atmospheric boundary layer; Surface energy balance; Soil model; Stable layer parameterization; Surface fluxes. (jhd).
Book Synopsis An Introduction to Boundary Layer Meteorology by : Roland B. Stull
Download or read book An Introduction to Boundary Layer Meteorology written by Roland B. Stull and published by Springer Science & Business Media. This book was released on 1988-07-31 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt: Part of the excitement in boundary-layer meteorology is the challenge associated with turbulent flow - one of the unsolved problems in classical physics. An additional attraction of the filed is the rich diversity of topics and research methods that are collected under the umbrella-term of boundary-layer meteorology. The flavor of the challenges and the excitement associated with the study of the atmospheric boundary layer are captured in this textbook. Fundamental concepts and mathematics are presented prior to their use, physical interpretations of the terms in equations are given, sample data are shown, examples are solved, and exercises are included. The work should also be considered as a major reference and as a review of the literature, since it includes tables of parameterizatlons, procedures, filed experiments, useful constants, and graphs of various phenomena under a variety of conditions. It is assumed that the work will be used at the beginning graduate level for students with an undergraduate background in meteorology, but the author envisions, and has catered for, a heterogeneity in the background and experience of his readers.
Book Synopsis Analyses of Turbulence in the Neutrally and Stably Stratified Planetary Boundary Layer by : Cedrick Ansorge
Download or read book Analyses of Turbulence in the Neutrally and Stably Stratified Planetary Boundary Layer written by Cedrick Ansorge and published by Springer. This book was released on 2016-10-04 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a study of strong stratification and turbulence collapse in the planetary boundary layer, opening a new avenue in this field. It is the first work to study all regimes of stratified turbulence in a unified simulation framework without a break in the paradigms for representation of turbulence. To date, advances in our understanding and the parameterization of turbulence in the stable boundary layer have been hampered by difficulties simulating the strongly stratified regime, and the analysis has primarily been based on field measurements. The content presented here changes that paradigm by demonstrating the ability of direct numerical simulation to address this problem, and by doing so to remove the uncertainty of turbulence models from the analysis. Employing a stably stratified Ekman layer as a simplified physical model of the stable boundary layer, the three stratification regimes observed in nature— weakly, intermediately and strongly stratified—are reproduced, and the data is subsequently used to answer key, long-standing questions. The main part of the book is organized in three sections, namely a comprehensive introduction, numerics, and physics. The thesis ends with a clear and concise conclusion that distills specific implications for the study of the stable boundary layer. This structure emphasizes the physical results, but at the same time gives relevance to the technical aspects of numerical schemes and post-processing tools. The selection of the relevant literature during the introduction, and its use along the work appropriately combines literature from two research communities: fluid dynamics, and boundary-layer meteorology.
Book Synopsis Turbulence Nature and the Inverse Problem by : L. N. Pyatnitsky
Download or read book Turbulence Nature and the Inverse Problem written by L. N. Pyatnitsky and published by Springer Science & Business Media. This book was released on 2009-03-22 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrodynamic equations well describe averaged parameters of turbulent steady flows, at least in pipes where boundary conditions can be estimated. The equations might outline the parameters fluctuations as well, if entry conditions at current boundaries were known. This raises, in addition, the more comprehensive problem of the primary perturbation nature, noted by H.A. Lorentz, which still remains unsolved. Generally, any flow steadiness should be supported by pressure waves emitted by some external source, e.g. a piston or a receiver. The wave plane front in channels quickly takes convex configuration owing to Rayleigh's law of diffraction divergence. The Schlieren technique and pressure wave registration were employed to investigate the wave interaction with boundary layer, while reflecting from the channel wall. The reflection induces boundary-layer local separation and following pressure rapid increase within the perturbation zone. It propagates as an acoustic wave packet of spherical shape, bearing oscillations of hydrodynamic parameters. Superposition of such packets forms a spatio-temporal field of oscillations fading as 1/r. This implies a mechanism of the turbulence. Vorticity existing in the boundary layer does not penetrate in itself into potential main stream. But the wave leaving the boundary layer carries away some part of fluid along with frozen-in vorticity. The vorticity eddies form another field of oscillations fading as 1/r2. This implies a second mechanism of turbulence. Thereupon the oscillation spatio-temporal field and its randomization development are easy computed. Also, normal burning transition into detonation is explained, and the turbulence inverse problem is set and solved as applied to plasma channels created by laser Besselian beams.
Book Synopsis Large-eddy Simulation of the Development of Stably-stratified Atmospheric Boundary Layers Over Cool Flat Surfaces by :
Download or read book Large-eddy Simulation of the Development of Stably-stratified Atmospheric Boundary Layers Over Cool Flat Surfaces written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Shock Wave-Boundary-Layer Interactions by : Holger Babinsky
Download or read book Shock Wave-Boundary-Layer Interactions written by Holger Babinsky and published by Cambridge University Press. This book was released on 2011-09-12 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shock wave-boundary-layer interaction (SBLI) is a fundamental phenomenon in gas dynamics that is observed in many practical situations, ranging from transonic aircraft wings to hypersonic vehicles and engines. SBLIs have the potential to pose serious problems in a flowfield; hence they often prove to be a critical - or even design limiting - issue for many aerospace applications. This is the first book devoted solely to a comprehensive, state-of-the-art explanation of this phenomenon. It includes a description of the basic fluid mechanics of SBLIs plus contributions from leading international experts who share their insight into their physics and the impact they have in practical flow situations. This book is for practitioners and graduate students in aerodynamics who wish to familiarize themselves with all aspects of SBLI flows. It is a valuable resource for specialists because it compiles experimental, computational and theoretical knowledge in one place.
Book Synopsis Atmospheric Boundary Layers by : Alexander Baklanov
Download or read book Atmospheric Boundary Layers written by Alexander Baklanov and published by Springer Science & Business Media. This book was released on 2007-10-30 with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents peer-reviewed papers from the NATO Advanced Research Workshop on Atmospheric Boundary Layers held in April 2006. The papers are divided into thematic sessions: nature and theory of turbulent boundary layers; boundary-layer flows: modeling and applications to environmental security; nature, theory and modeling of boundary-layer flows; air flows within and above urban and other complex canopies: air-sea-ice interaction.
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722425272 Total Pages :28 pages Book Rating :4.4/5 (252 download)
Book Synopsis Numerical Modeling Studies of Wake Vortex Transport and Evolution Within the Planetary Boundary Layer by : National Aeronautics and Space Administration (NASA)
Download or read book Numerical Modeling Studies of Wake Vortex Transport and Evolution Within the Planetary Boundary Layer written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-11 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: In support of the wake vortex effect of the Terminal Area Productivity program, we have put forward four tasks to be accomplished in our proposal. The first task is validation of two-dimensional wake vortex-turbulence interaction. The second task is investigation of three-dimensional interaction between wake vortices and atmospheric boundary layer (ABL) turbulence. The third task is ABL studies. The, fourth task is addition of a Klemp-Durran condition at the top boundary for TASS model. The accomplishment of these tasks will increase our understanding of the dynamics of wake vortex and improve forecasting systems responsible for air safety and efficiency. The first two tasks include following three parts: (a) Determine significant length scale for vortex decay and transport, especially the length scales associated with the onset of Crow instability (Crow, 1970); (b) Study the effects of atmospheric turbulence on the decay of the wake vortices; and (c) Determine the relationships between decay rate, transport properties and atmospheric parameters based on large eddy simulation (LES) results and the observational data. These parameters may include turbulence kinetic energy, dissipation rate, wind shear and atmospheric stratification. The ABL studies cover LES modeling of turbulence structure within planetary boundary layer under transition and stable stratification conditions. Evidences have shown that the turbulence in the stable boundary layer can be highly intermittent and the length scales of eddies are very small compared to those in convective case. We proposed to develop a nesting grid mesh scheme and a modified Klemp-Durran conditions (Klemp and Wilhelmson, 1978) at the top boundary for TASS model to simulate planetary boundary layer under stable stratification conditions. During the past year, our group has made great efforts to carry out the above mentioned four tasks simultaneously. The work accomplished in the last year will be described in the next sectio...
