TY - BOOK TI - An Introduction to Dynamic Meteorology SN - 9780123848666 U1 - 551.515 PY - 2013/// CY - Amsterdam PB - Elsevier N1 - 1. Introduction 1.1 Dynamic Meteorology 1 1.2 Conservation of Momentum 4 1.2.1 Pressure Gradient Force 5 1.2.2 Viscous Force 6 1.2.3 Gravitational Force 8 1.3 Noninertial Reference Frames and "Apparent" Forces 9 1.3.1 Centripetal Acceleration and Centrifugal Force 10 1.3.2 Gravity Revisited 11 1.3.3 The Coriolis Force and the Curvature Effect 14 1.3.4 Constant Angular Momentum Oscillations 17 1.4 Structure of the Static Atmosphere 18 1.4.1 The Hydrostatic Equation 18 1.4.2 Pressure as a Vertical Coordinate 20 1.4.3 A Generalized Vertical Coordinate 22 1.5 Kinematics 23 1.6 Scale Analysis 25 Suggested References 26 Problems 26 Matlab Exercises 28 2. Basic Conservation Laws 2.1 Total Differentiation 31 2.1.1 Total Differentiation ofa Vector in a Rotating System 33 2.2 TheVectorial Form of the Momentum Equation In Rotating Coordinates 35 2.3 Component Equations in Spherical Coordinates 37 2.4 Scale Analysis of the Equations of Motion 41 2.4.1 Geostrophic Approximation and Geostrophic Wind 42 2.4.2 Approximate Prognostic Equations: The Rossby Number 43 2.4.3 The Hydrostatic Approximation 44 2.5 The Continuity Equation 45 2.5.1 A Eulerian Derivation 46 2.5.2 A Lagrangian Derivation 47 2.5.3 Scale Analysis of the Continuity Equation 48 2.6 The Thermodynamic Energy Equation 50 VII (TnT) 2.7 Thermodynamics of the Dry Atmosphere 53 2.7.1 Potential Temperature 53 2.7.2 The Adiabatic Lapse Rate 54 2.7.3 Static Stability 54 2.7.4 Scale Analysis of the Thermodynamic Energy Equation 56 2.8 The Boussinesq Approximation 57 2.9 Thermodynamics of the Moist Atmosphere 58 2.9.1 Equivalent Potential Temperature 59 2.9.2 The Pseudoadiabatic Lapse Rate 61 2.9.3 Conditional Instability 52 Suggested References 54 Problems 55 Matlab Exercises 55 3. Elementary Applications of the Basic Equations 3.1 Basic Equations In Isobaric Coordinates 67 3.1.1 The Horizontal Momentum Equation 67 3.1.2 The Continuity Equation 53 3.1.3 The Thermodynamic Energy Equation 69 3.2 Balanced Flow 3.2.1 Natural Coordinates 70 3.2.2 Geostrophic Flow 71 3.2.3 Inertial Flow 72 3.2.4 Cyclostrophic Flow 73 3.2.5 The Gradient Wind Approximation 74 3.3 Trajectories and Streamlines 78 3.4 The Thermal Wind 81 3.4.1 Barotropic and Baroclinic Atmospheres 84 3.5 Vertical Motion 84 3.5.1 The Kinematic Method 85 3.5.2 The Adiabatic Method 87 3.6 Surface Pressure Tendency 87 Problems gg Matlab Exercises 92 4. Circulation, Vorticity, and Potential Vorticity 4.1 The Circulation Theorem 95 4.2 Vorticity 100 4.2.1 Vorticity in Natural Coordinates 102 4.3 The Vorticity Equation 104 4.3.1 Cartesian Coordinate Form 104 4.3.2 The Vorticity Equation in Isobaric Coordinates 106 4.3.3 Scale Analysis ofthe Vorticity Equation 107 4.4 Potential Vorticity 110 4.5 Shallow Water Equations 115 4.5.1 Barotropic Potential Vorticity 118 Contents Contents 4.6 Ertel Potential Vorticity in Isentropic Coordinates 4.6.1 Equations of Motion in Isentropic Coordinates 4.6.2 The Potential Vorticity Equation 4.6.3 Integral Constraints on Isentropic Vorticity Suggested References ^22 Problems Matlab Exercises 5. Atmospheric Oscillations 5.1 The Perturbation Method 5.2 Properties of Waves 5.2.1 Fourier Series 5.2.2 Dispersion and Group Velocity 5.2.3 Wave Properties in Two and Three Dimensions 5.2.4 AWave Solution Strategy 5.3 Simple WaveTypes 5.3.1 Acoustic or SoundWaves 5.3.2 Shallow Water Waves 5.4 Internal Gravity (Buoyancy) Waves 5.4.1 Pure Internal Gravity Waves 5.5 Linear Waves of a Rotating Stratified Atmosphere 5.5.1 Pure Inertial Oscillations 5.5.2 Rossby and Inertia-Gravity Waves 5.6 Adjustment to Geostrophic Balance 5.7 Rossby Waves ' 5.7.1 Free Barotropic Rossby Waves 5.7.2 Forced Topographic Rossby Waves Suggested References ^ Problems Matlab Exercises 6. Quasi-geostrophic Analysis 6.1 The Observed Structure ofExtratroplcal Circulations 6.2 Derivation ofthe Quasi-Geostrophic Equations 6.2.1 Preliminaries 6.3 Potential Vorticity Derivation ofthe QG Equations 6.4 Potential Vorticity Thinking . • ia« 6.4.1 PV Inversion, Induced Flow, and Piecewise nversion 6.4.2 PV Conservation and the QG "Height Tendency" Equation 194 6.5 Vertical Motion (w) Thinking 6.6 Idealized Model of a Baroclinic Disturbance 6.7 Isobaric Form of the QG Equations Suggested References Problems Matlab Exercises QD 120 120 121 121 122 124 127 128 130 131 133 135 136 136 139 144 145 150 150 152 156 159 171 178 181 183 187 197 204 206 208 210 CZ) Contents 7. Baroclinic Development 7.1 Hydrodynamic Instability 213 7.2 Normal Mode Baroclinic Instability; ATwo-Layer Model 215 7.2.1 Linear Perturbation Analysis 217 7.2.2 Vertical Motion in Baroclinic Waves 223 7.3 The Energetics of Baroclinic Waves 227 7.3.1 Available Potential Energy 227 7.3.2 Energy Equations for the Two-Layer Model 229 7.4 Baroclinic Instability of a Continuously Stratified Atmosphere 234 7.4.1 Log-Pressure Coordinates 235 7.4.2 Baroclinic Instability: The Rayleigh Theorem 237 7.4.3 The Eady Stability Problem 241 7.5 Growth and Propagation of Neutral Modes 245 7.5.1 Transient Growth of Neutral Waves 247 7.5.2 Downstream Development 250 Suggested References 251 Problems 251 Matlab Exercises 253 8. The Planetary Boundary Layer 8.1 Atmospheric Turbulence 256 8.1.1 Reynolds Averaging 256 8.2 Turbulent Kinetic Energy 259 8.3 Planetary Boundary Layer Momentum Equations 261 8.3.1 Well-Mixed Boundary Layer 262 8.3.2 The Flux-Gradient Theory 264 8.3.3 The Mixing Length Hypothesis 264 8.3.4 The Ekman Layer 266 8.3.5 The Surface Layer 268 8.3.6 The Modified Ekman Layer 269 8.4 Secondary Circulations and Spin Down 270 Suggested References 275 Problems 275 Matlab Exercises 276 9. Mesoscale Circulations 9.1 Energy Sources for Mesoscale Circulations 279 9.2 Fronts and Frontogenesis 280 9.2.1 The Kinematics of Frontogenesis 281 9.2.2 Semigeostrophic Theory 285 9.2.3 Cross-Frontal Circulation 287 9.3 Symmetric Baroclinic Instability 290 9.4 Mountain Waves 294 9.4.1 Wavesover Sinusoidal Topography 294 9.4.2 Flow over Isolated Ridges 297 Contents 9.4.3 Lee Waves 9.4.4 Downslope Windstorms 299 9.5 Cumulus Convection 9.5.1 Convective Available Potential Energy 302 9.5.2 Entrainment 9.6 Convective Storms 9.6.1 Development of Rotation in Supercell Thunderstorms 306 9.6.2 The Right-Moving Storm 310 9.7 Hurricanes 9.7.1 Dynamics of Mature Hurricanes 314 9.7.2 Hurricane Development 318 Suggested References Problems ^22 Matlab Exercises 10. The General Circulation 10.1 The Nature of the Problem 326 10.2 The Zonally Averaged Circulation 32« 10.2.1 The Conventional Eulerian Mean 3JU 10.2.2 The Transformed Eulerian Mean 337 10^2.3 The Zonal-Mean Potential Vorticity Equation 10.3 The Angular Momentum Budget 10.3.1 Sigma Coordinates 10.3.2 The Zonal-Mean Angular Momentum 10.4 The Lorenz EnergyCycle 10.5 Longitudinally Dependent Time-Averaged Flow 10.5.1 Stationary Rossby Waves 10.5.2 Jet Stream and Storm Tracks 10.6 Low-Frequency Variability 10.6.1 Climate Regimes 10.6.2 Annular Modes 10.6.3 Sea Surface Temperature Anomalies 10.7 Numerical Simulation of the General Circulation 10.7.1 Dynamical Formulation 10.7.2 Physical Processes and Parameterizations 10.8 Climate Sensitivity, Feedbacks, and Uncertainty 11.1.5 The Walker Circulation 389 n .1.6 El Nino and the Southern Oscillation 390 11.1.7 Equatorial Intraseasonal Oscillation 392 11.2 Scale Analysis of Large-Scale Tropical Motions 392 11.3 Condensation Heating 398 11.4 Equatorial Wave Theory 401 11.4.1 Equatorial Rossby and Rossby-Gravity Modes 401 11.4.2 Equatorial Kelvin Waves 404 11.5 Steady Forced Equatorial Motions 406 Suggested References 409 Problems 409 Matlab Exercises 410 12. Middle Atmosphere Dynamics 12.1 Structure and Circulation of the Middle Atmosphere 413 12.2 The Zonal-Mean Circulation of the Middle Atmosphere 417 12.2.1 Lagrangian Motion of Air Parcels 418 12.2.2 The Transformed Eulerian Mean 420 12.2.3 Zonal-Mean Transport 424 12.3 Vertically Propagating Planetary Waves 426 12.3.1 Linear Rossby Waves 426 12.3.2 Rossby Wave Breaking 428 12.4 Sudden Stratospheric Warmings 430 12.5 Waves in the Equatorial Stratosphere 435 12.5.1 Vertically Propagating Kelvin Waves 436 12.5.2 Vertically Propagating Rossby-Gravity Waves 437 12.5.3 Observed Equatorial Waves 438 12.6 The Quasi-Biennial Oscillation 44O 12.7 Trace Constituent Transport 446 12.7.1 Dynamical Tracers 446 12.7.2 Chemical Tracers 447 12.7.3 Transport in the Stratosphere 448 Suggested References 45O Problems 45O Matlab Exercises 452 13. Numerical Modeling and Prediction 13.1 Historical Background 453 13.2 Numerical Approximation of the Equations of Motion 455 13.2.1 Finite Differences 455 13.2.2 Centered Differences: Explicit Time Differencing 457 13.2.3 Computational Stability 458 13.2.4 Implicit Time Differencing 45O 13.2.5 The Semi-Lagrangian Integration Method 462 13.2.6 Truncation Error 453 13.3 The Barotropic Vorticity Equation In Finite Differences 464 Contents GiD 13.4 The Spectral Method 13.4.1 The Barotropic Vorticity Equation in Spherical Coordinates 468 13.4.2 Rossby-Haurwitz Waves 470 13.4.3 The Spectral Transform Method 471 13.5 Primitive Equation Models 472 13.5.1 Spectral Models 473 13.5.2 Physical Parameterizations 474 13.6 Data Assimilation 13.6.1 Data Assimilation for a Single Variable 476 13.6.2 Data Assimilation for Many Variables 479 13.7 Predictability and Ensemble Forecasting 481 Suggested References Problems Matlab Exercises Appendices A. Useful Constants and Parameters 491 B. List of Symbols C. Vector Analysis C.1 Vector Identities ^ C.2 Integral Theorems ^ C.3 Vector Operations in Various Coordinate Systems D. Moisture Variables D.1 Equivalent Potential Temperature D.2 Pseudo Adiabatic Lapse Rate E. Standard Atmosphere Data F. Symmetric Baroclinic Oscillations C. Conditional Probability and Likelihood 511 ER -