Skip to main content
Fachgebiete
Automobil + Motoren Bauwesen + Immobilien Business IT + Informatik Elektrotechnik + Elektronik Energie + Nachhaltigkeit Finance + Banking Management + Führung Marketing + Vertrieb Maschinenbau + Werkstoffe Versicherung + Risiko
DE
EN
Bücher
Zeitschriften
Themenseiten
Organisationspsychologie Projektmanagement Marketing Smart Manufacturing
Weitere Formate
Podcasts Webinare Technik Webinare Wirtschaft Kongresse Veranstaltungskalender Awards
Jetzt Einzelzugang starten
Zugang für Unternehmen
Referenzkunden
SLX-Digitalkonferenz: Zukunftswerkstatt 2024

Mehr Umsatz mit Top-Kontakten

Am 7. Mai erfahren Sie, wie Vertriebsteams Leadgenerierung, Leadnurturing und Leadstrategien effizient steuern können.
Erweiterte Suche
Anmelden
nach oben

1988 | Buch

Mean Boundary Layer Characteristics Kapitel lesen Erstes Kapitel lesen

An Introduction to Boundary Layer Meteorology

herausgegeben von: Roland B. Stull

Verlag: Springer Netherlands

Buchreihe : Atmospheric and Oceanographic Sciences Library

Enthalten in: Professional Book Archive

Einloggen, um Zugang zu erhalten
insite
SUCHEN

Über dieses Buch

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.

Inhaltsverzeichnis

Frontmatter
1. Mean Boundary Layer Characteristics
Abstract
From our first breath, we spend most of our lives near the earth’s surface. We feel the warmth of the daytime sun and the chill of the nighttime air. It is here where our crops are grown, our dwellings are constructed, and much of our commerce takes place. We grow familiar with our local breezes and microclimates, and we sense the contrasts when we travel to other places.
Roland B. Stull
2. Some Mathematical & Conceptual Tools: Part 1. Statistics
Abstract
Turbulence is an intrinsic part of the atmospheric boundary layer that must be quantified in order to study it. The randomness of turbulence makes deterministic description difficult. Instead, we are forced to retreat to the use of statistics, where we are limited to average or expected measures of turbulence. In this chapter we review some basic statistical methods and show how measurements of turbulence can be put into a statistical framework. Usually, this involves separating the turbulent from the nonturbulent parts of the flow, followed by averaging to provide the statistical descriptor.
Roland B. Stull
3. Application of the Governing Equations to Turbulent Flow
Abstract
To quantitatively describe and forecast the state of the boundary layer, we turn to the equations of fluid mechanics that describe the dynamics and thermodynamics of the gases in our atmosphere. Motions in the boundary layer are slow enough compared to the speed of light that the Galilean/Newtonian paradigm of classical physics applies. These equations, collectively known as the equations of motion, contain time and space derivatives that require initial and boundary conditions for their solution.
Roland B. Stull
4. Prognostic Equations for Turbulent Fluxes and Variances
Abstract
In the previous chapter, we summarized the equations needed to forecast mean wind, temperature, humidity, and pollutants. The last term in each of equations (3.5.3c) through (3.5.3g) contains a covariance like \( \overline {{u_{j}}^{'}{\theta ^{'}}} \) or \( \overline {{u_{j}}{}^{'}{c^{'}}} \). In order to use those previous equations, we can either evaluate the covariances experimentally, or we can derive additional equations to forecast the covariances.
Roland B. Stull
5. Turbulence Kinetic Energy, Stability and Scaling
Abstract
Turbulence kinetic energy (TKE) is one of the most important variables in micrometeorology, because it is a measure of the intensity of turbulence. It is directly related to the momentum, heat, and moisture transport through the boundary layer. Turbulence kinetic energy is also sometimes used as a starting point for approximations of turbulent diffusion.
Roland B. Stull
6. Turbulence Closure Techniques
Abstract
At first glance, the large number of equations developed in Chapters 3-5 would suggest that we have a fairly complete description of turbulent flow. Unfortunately, a closer examination reveals that there are a large number of unknowns remaining in those equations. These unknowns must be dealt with in order end up with a useful description of turbulence that can be applied to real situations. In this Chapter, the unknowns are identified, and methods to parameterize them are reviewed. Simulation techniques such as large-eddy simulation are discussed in Chapter 10.
Roland B. Stull
7. Boundary Conditions and Surface Forcings
Abstract
Without a bottom boundary on the atmosphere there would be no boundary layer. Friction at the surface slows the wind, and heat and moisture fluxes from the surface modify the state of the boundary layer. The heat and moisture fluxes are driven, in turn, by the external forcings such as radiation from the sun or transpiration from plants. Forcings across the top of the boundary layer also alter mean characteristics within it.
Roland B. Stull
8. Some Mathematical & Conceptual Tools: Part 2. Time Series
Abstract
Spectrum analysis is a statistical tool that we can employ to probe further into the workings of turbulence. By decomposing a series of measurements into frequency or wavenumber components, we can discover how eddies of different time and space scales contribute to the overall turbulence state.
Roland B. Stull
9. Similarity Theory
Abstract
For a number of boundary layer situations, our knowledge of the governing physics is insufficient to derive laws based on first principles. Nevertheless, boundary layer observations frequently show consistent and repeatable characteristics, suggesting that we could develop empirical relationships for the variables of interest. Similarity theory provides a way to organize and group the variables to our maximum advantage, and in turn provides guidelines on how to design experiments to gain the most information.
Roland B. Stull
10. Measurement and Simulation Techniques
Abstract
Our fundamental understanding of the boundary layer comes from measurements. Most measurements are made in the field, some are made in laboratory tank or wind tunnel simulations, and some are samples from numerical simulations. Theories and parameterizations, such as presented in earlier chapters, are valuable only if they describe the observed boundary layer behavior.
Roland B. Stull
11. Convective Mixed Layer
Abstract
Buoyancy is the dominant mechanism driving turbulence in a convective boundary layer. Such turbulence is not completely random, but is often organized into identifiable structures such as thermals and plumes (Young, 1988). Entertainment happens at a variety of scales: lateral entertainment by small eddies into the sides of thermals, and vertical entertainment on the thermal scale into the whole mixed layer. In this chapter we examine the structure and evolution of the convective boundary layer, and study the forcings acting on it.
Roland B. Stull
12. Stable Boundary Layer
Abstract
The boundary layer can become stably stratified whenever the surface is cooler than the air. This stable boundary layer (SBL) often forms at night over land, where it is known as a nocturnal boundary layer (NBL). It can also form by advection of warmer air over a cooler surface.
Roland B. Stull
13. Boundary Layer Clouds
Abstract
Clouds can form at the top of mixed layers, and at the bottom of stable boundary layers. The amount and distribution of short and long-wave radiative flux divergence in the boundary layer are altered by clouds, and these effects are emerging as important aspects of the climate-change problem. In addition, the radiative effects combine with latent heating to modulate BL dynamics, turbulence generation, and evolution. This chapter provides a brief review of cloud thermodynamics, radiative processes, the role of entrainment, and descriptions of fogs, cumulus and stratocumulus clouds.
Roland B. Stull
14. Geographic Effects
Abstract
In most of the previous chapters we assumed a flat, uniform bottom boundary, but in many parts of the world the ground is neither flat nor uniform. Geographic variations can modify the boundary-layer flow, and in some cases generate circulations in conjunction with diurnal heating cycles. We have already touched on a few such flows, such as the drainage winds at night within a stable boundary layer. In this chapter we examine both geographically-generated and geographically-modified flows.
Roland B. Stull
Errata
Roland B. Stull
Backmatter
Metadaten
Titel
An Introduction to Boundary Layer Meteorology
herausgegeben von
Roland B. Stull
Copyright-Jahr
1988
Verlag
Springer Netherlands
Electronic ISBN
978-94-009-3027-8
Print ISBN
978-90-277-2769-5
DOI
https://doi.org/10.1007/978-94-009-3027-8