Atmospheric Boundary Layers and Air Pollution Modelling

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Lecture Notes Course at ETHZ Mathias W. Rotach

IDEAL AND FLAT

BOUNDARY LAYER VISBLE FROM A FOREST FIRE

IN COMPLEX TOPOGRAPHY

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Real and Ideal

Content

1 Introduction

1.1 The Atmospheric Boundary Layer 1.2 Phenomenological Overview 1.3 Daily Cycle

Part I Ideal Boundary Layers

2 A Brief Introduction to Atmospheric Turbulence 2.1 The Turbulence Syndrome

2.2 The Reynolds Number 2.3 Laminar vs. Turbulent Flows 3 Statistical Treatment of Turbulence

3.1 Averaging, Stationarity and Homogeneity 3.2 Taylor Hypothesis

3.3 Reynolds Decomposition

3.4 Co-Variances and their Physical Meaning 3.5 Other Turbulence Variables

4 Similarity Theory 4.1 Motivation

4.2 Scaling and similarity 4.3 Practical Approach

4.4 Monin-Obukhov Similarity Theory for the Surface Layer 4.5 Scaling Regimes

5 Conservation Equations for Turbulent Flows

5.1 Conservation Equations for Mean Variables in a Turbulent Flow 5.2 Closure Problem and Closures

5.3 An Idealised Solution: The Ekman spiral 6 Turbulent Kinetic Energy and Dynamical Stability

6.1 TKE-Equation 6.2 Stability Measures 7 Turbulence Spectra

7.1 Introduction to spectral analysis 7.2 Energy Cascade

7.3 Kolmogorov Hypotheses 7.4 Spectra and Co-spectra

7.5 Application of Spectral Information

Part II Modifications in Real Boundary Layers 8 Non-ideal boundary layers

8.1 Overview

8.2 Non-horizontally homogeneous surfaces 8.3 Large roughness elements

8.4 Influence of topography 9 Horizontal heterogeneity

9.1 Simple two-surface systems 9.2 Heterogeneous surfaces

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10 Flow over Rough Surfaces 10.1 General considerations 10.2 Mean profiles

10.3 Higher order turbulence statistics 10.4 Coherent structures

11 Boundary Layers over Topography 11.1 Flow over Gentle Hills 11.2 Valley Boundary Layers Part III Air Pollution Modelling

12 Atmospheric Dispersion Modelling 12.1 Overview

12.2 Statistical Theory of Taylor

12.3 Semi-empirical Methods for the Plume Characteristics