Modelling of Atmospheric Flow Fields

The following sections are included:

• Foreword

• Introduction

• Contents

The following sections are included:

• The energy budget in the atmosphere
  • Solar and terrestrial radiation
  • The thermal structure of the atmosphere
  • Interaction between radiation and atmosphere
  • The role of sensible and latent heat
  • The phase changes of water
  • The different behaviour of land and sea

• The temperature in the low atmosphere
  • The daily cycle of the energy balance
  • Vertical motions of air
  • The temperature lapse rate
  • The air stability

• The forces affecting the wind field
  • The pressure gradient force
  • The Coriolis force
  • The geostrophic and the gradient wind
  • The effect of friction on the wind
  • Wind around high and low pressure systems

• The Atmospheric Boundary Layer
  • Definition of the ABL
  • The ABL sublayers

• References

The following sections are included:

• Basic Considerations

• Surface energy balance

• Temperature variations in the ABL

• Wind variations in the ABL

• The nocturnal low level jet

• Spatial variations in the ABL

• Roughness changes in the surface layer

• References

The following sections are included:

• Introduction

• Averaged equations

• First–order closure methods

• Turbulent fluxes in the surface layer

• Empirical relations in the Ekman layer

• Mixing length approach

• Influence of thermal stratification on the mixing length

• Equation for the turbulent kinetic energy

• Subgrid length scale and mixing length

• The E–ε turbulence model

• Second order closure models

• References

The following sections are included:

• Introduction

• Surface layer
  • Neutral surface layer
  • Diabatic surface layer

• Boundary layer
  • Neutral boundary layer
  • Convective boundary layer
  • Stable boundary layer

• References

The following sections are included:

• Introduction

• Turbulence parameters
  • The surface layer
  • The free convection layer
  • The mixing layer

• In–situ turbulence measurement sensors
  • Description of the system

• Probe performance on a fixed support

• References

The following sections are included:

• Introduction

• Remote sensing with different techniques: similarities and differences

• General principles of remote sensing

• Acoustic scattering theory

• Radioacoustic scattering theory

• Optical wave scattering theory

• Sodar applications in the PBL

• RASS applications in the PBL

• Lidar applications in the PBL
  • Aerosol loading, plume trajectories, smoke dispersion
  • Gas detection
  • Wind profiles
  • Temperature

• Conclusions

• References

The following sections are included:

• Introduction

• Atmospheric Acoustic Sounders
  • Acoustic Sounder Design
  • The Acoustic Sounder Antenna
  • Thermal Plumes
  • Inversions
  • Diurnal Variation of the Convective Boundary Layer
  • Stable Conditions and Waves
  • Acoustic Sounding of Clouds
  • Acoustic Sounding of Radiation Fog
  • Measurement of Structure Parameters and Turbulence Dissipation Rate

• References

The following sections are included:

• Introduction

• Experimental set-up and data analysis

• Determination of the surface roughness

• Model description

• Comparison between model and data

• Large scale roughness length

• Equilibrium height for the internal boundary layer

• Conclusion and discussion

• Acknowledgements

• References

The following sections are included:

• Introduction

• Atmospheric Data

• Formulae

• Comparison of Formulae and Atmospheric Data

• Comparison of Formulae in the Longer Range

• Summary and Conclusion

• References

The following sections are included:

• Introduction

• The Mean Flow Over A Low Hill

• Turbulence structure in flow over a low hill

• Separated Flows

• Turbulence in complex terrain with flow separation

• The influence of static–stability

• References

The following sections are included:

• Introduction

• The vertical scales of the oncoming flow

• Modification in the boundary layer encountering an isolated topographic obstacle
  • Stratification Effects in the Outer Region of Flow
  • The Inner Viscous Region
  • Shear Effects in the Bulk of the Boundary Layer

• Turbulence perturbations in the flow over obstacles
  • The Turbulence in the Inner Region
  • Distortion of Turbulence in the Main Part of the Boundary Layer

• Summary of the problem of flow over an isolated, small slope obstacle

• Separation

• The boundary layer over complex terrain

• Conclusions

• References

The following sections are included:

• Introduction

• Economics Of Wind Energy Production

• The Importance of siting

• Siting requirements

• Wind Prospecting and Siting

• Siting Methods

• Future needs

• References

The following sections are included:

• Introduction

• Measurements
  • Siting of Small Turbines
  • Siting of Larger Turbines

• Numerical Modeling
  • Description of Models
  • Diagnostic Models
  • Prognostic Models
  • Description of Data Sets
  • Results And Remarks
  • Recent Research

• The Models At Askervein Hill

• The Models in Altamont Pass

• Siting of Two or More Turbines

• Concluding remarks

• Acknowledgments

• References

The following sections are included:

• Introduction

• The general approach
  • The inizialization and the adjustment steps
  • Continuity equation

• The variational technique
  • Sasaki's method
  • Boundary conditions

• Parametrization of stability

• Discretization of the domain
  • The 3-D grid
  • The Cartesian coordinate system
  • Terrain conformal coordinate system
  • Height of the domain
  • Horizontal spacing
  • Vertical spacing
  • Typical grid dimensions and spacings

• The initialization process
  • General considerations
  • Vertical extrapolation
  • Horizontal interpolation

• Numerical solution of differential equations

• Model testing

• Conclusions

• References

The following sections are included:

• Introduction

• Objective analysis/time dependent numerical modeling combined procedure
  • The time dependent PBL model
  • Initial and boundary conditions for the PBL model
  • Diagnostic model
  • Linearity of the NOABL equations

• Verification methodology
  • Field experiment
  • Numerical simulation

• Results and discussions

• References

The following sections are included:

• Model description

• Parameterization of α²

• Summary

• References

The following sections are included:

• Introduction

• Windfield initialization
  • NOABL initialization
  • AIOLOS initialization
  • WINDS initialization
  • Wind profiles used in AIOLOS
  • Wind profiles used in WlNDS

• Observed profiles

• Applications

• References

The following sections are included:

• Introduction

• The physical basis

• The W A^sP model

• The application model

• The orographic model

• References

The following sections are included:

• Introduction

• Limitations of Linearized Models

• The MS3DJH/3R code

• Acknowledgements

• References

The following sections are included:

• Introduction
  • MS–Micro/2
  • Background to MS–Micro

• Background
  • History
  • Background Material and Brief Description

• Hardware
  • Microcomputer
  • Graphics Card and Monitor
  • Printer
  • Plotter
  • Digitizer

• Software
  • Introduction
  • Software Overview
  • Operating System Considerations
  • Core Programs

• References

The following sections are included:

• Introduction

• Jackson and Hunt models

• Mass consistent Models

• Conclusions

• References

The following sections are included:

• Introduction

• Field Experiment

• Model Descriptions
  • Mason–King model D
  • MS–Micro
  • BZ-WASP
  • NOABL*
  • Guidelines estimates

• Topographic Data

• Comparison of Results
  • Contour plots
  • Cross–sections
  • Wind profiles
  • Comparisons at site C
  • Azimuthal plots

• Conclusions

• Acknowledgements

• References

The following sections are included:

• Physics of the atmospheric boundary layer

• Structure of prognostic mesoscale models

• Description of a fully vectorized prognostic mesoscale model
  • Model equations
  • Transformation to terrain–following coordinates
  • Numerical solution of the equation system
  • Parameterizations
  • Initial and boundary conditions

• Simulation of the steady–state inviscid flow over a single mountain

• Simulation of the sea breeze circulation in Athens

• Summary

• References

The following sections are included:

• Introduction

• Model description
  • Horizontal grid and horizontal coordinates
  • Vertical coordinate, orography and vertical resolution
  • Prognostic variables and basic equations
  • Time and space differencing
  • Treatment of physical processes

• Model orography, initial and boundary conditions

• Model results

• Conclusion

• Acknowledgments

• References

The following sections are included:

• Introduction

• Linearized periodically forced model
  • The scaled basic equations
  • Method of solution
  • Limit of large wavenumbers
  • Vertical variation of diffusivity and stratification

• Numerical Model

• References

The following sections are included:

• Introduction
  • A description of the sea–land breeze wind

• An energy model for the sea–land breeze wind

• The analytical theory of the sea–land breeze

• A numerical approach to the sea–land breeze problem

• References

The following sections are included:

• Introduction

• Wind speed data bases
  • Representativeness of data bases
  • Correction of data bases
  • Transformation of data bases
  • Enucleation of exceptional aeolic phenomena

• Wind speed statistics
  • Bivariate Gaussian and derived distributions
  • Weibull distribution
  • The problem of the wind calms
  • Advanced models

• Conclusions and perspectives

• Acknowledgements

• References

The following sections are included:

• Introduction

• Ordinary aeolic phenomena
  • Process analysis
  • Population analysis
  • Asymptotic analysis
  • Comparison between different procedures

• Extreme wind speed statistics - extraordinary aeolic phenomena
  • Hurricanes
  • Tornadoes
  • Mixed wind statistics

• Conclusions and perspectives

• Acknowledgements

• References

In the following, the expressions in italics within a definition are the subject of a definition themselves.

ADIABATIC LAPSE-RATE – The rate of temperature decrease with height of a parcel displaced vertically in the atmosphere adiabatically. The parcel becomes cooler with lifting as it expands upon encountering less pressure; conversely, the parcel becomes warmer with descent as it is compressed due to higher pressures. The adiabatic lapse rate is a decrease of 0.98 °C per 100 m of ascent, assuming no condensation occurs. See also dry adiabatic and saturated adiabatic lapse rate…

The following sections are included:

• Introduction

• Equations used
  • Input data

• Running the program

• Reference

For computer demonstrations we choose a simple 1-D model for neutrally stratified boundary layer…

This one–dimensional time dependent model simulates the atmospheric boundary layer up to a height of three kilometers (only the lowest two kilometers are displayed). The vertical distributions of temperature, dew point and wind speed are displayed on a color screen, and this display is updated every ten minutes of model time (or every two minutes if desired) to provide a dynamically changing profiles of wind speed, temperature, and dew point. In addition, layers containing liquid water are indicated. An inset panel is provided so that the diurnal course of the terms in the surface heat balance equation can be followed graphically.

The following sections are included:

• Introduction

• Input Data Requirements

• Calculation of the Terrain Elevation Effect
  • Isolated Terrain Feature
  • Rolling Terrain

• Calculation of the Surface Roughness Effect
  • Single Roughness Change
  • Multiple Roughness Changes

• Combined Use of ΔS and ΔR

• Turbulence Intensity Estimates

• Non-Ideal Reference Sites

• More Sophisticated Numerical Models

• Note to Users

• Acknowledgements

• References

The code is designed in order to evaluate the horizontal velocity field induced by a simple isolated topography on an incoming boundary layer.

As input, the code requires some specification of the unperturbed boudary layer and of the shape of the topography. It estimates the perturbation velocity field according th the simplified model described in chapter… To do that, thefourier transform of the topography is computed first, based on an input matrix which specifies the topography height on the domain, at gridded points (the same points where the velocity will be computed)…

The following sections are included:

• I/O File description

• Subroutines used

• Specification of the input parameters

• Definition of additional variables
  • Variables
  • Arrays defining zoning setup
  • Arrays used in the initialization process
  • Flow variable arrays
  • Variables in boundary layer parameterization

The model Breeze solves a system of equations which include the continuity equation, the horizontal equations of motion, the non–hydrostatic non–elastic form of the vertical equation of motion, the thermodynamic equation and a K-theory turbulence scheme. The details of the theory on which the numerical model Breeze is based, are discussed in detail in the corresponding chapter in the main text. Typical results are also presentedx dthere and especially in the figures…

The following sections are included:

• List of lecturers

Please refer to full text.

Note from Publisher: This article contains the errata to pages 250–257 of the above article.