Introduction to the Dynamics of El Nino and the Southern Oscillation (eBook)

Cover 1
Table of Contents 8
Preface 14
Chapter 1 Introduction 18
References 24
Chapter 2 ENSO in the Tropical Pacific 28
2.1. Overview 28
2.2. Spatial Patterns of ENSO in the Tropical Pacific 28
2.2.1. The western equatorial Pacific region 150°E–150°W where ocean–atmosphere coupling is strongest 31
2.2.2. ENSO effects in the eastern Pacific 34
2.2.3. ENSO effects in the far western Pacific (120°E–140°E) 37
2.2.4. ENSO effects in the upper atmosphere 37
2.3. Time Series Structure of the ENSO Variables 41
2.4. A Physical Explanation for El Niño 45
References 48
Chapter 3 Equatorial Ocean Waves 50
3.1. Overview 50
3.2. The Linear Stratified Ocean Model 51
3.3. The Description of the Constant Depth Ocean Dynamics in Terms of Vertical Modes 54
3.3.1. The continuously stratified case 54
3.3.2. The two-layer stratification case 56
3.4. Equatorial Waves 63
3.4.1. The equatorial Kelvin wave 63
3.4.2. Other equatorial waves 65
3.4.3. Low-frequency equatorial waves 71
3.4.4. Energy flux and group velocity 72
References 73
Chapter 4 Equatorial Wave Reflection from Pacific Ocean Boundaries 74
4.1. Overview 74
4.2. Wave Reflection at the Western Pacific Boundary 75
4.2.1. Reflection from a solid meridional western boundary 75
4.2.2. Low-frequency reflection from a solid non-meridional western boundary 76
4.2.3. ENSO frequency reflection from the gappy western Pacific boundary 78
4.2.4. Interannual surface flow between the Pacific and Indian Oceans 82
4.3. Wave Reflection at the Eastern Pacific Ocean Boundary 84
4.3.1. Moore’s solution for the reflection of an equatorial Kelvin wave from a meridional eastern ocean boundary 85
4.3.2. The coastal Kelvin wave 87
4.3.3. Solution for ß-plane motions near the eastern boundary 89
4.3.4. Limiting forms of the near-boundary low-frequency solution 93
4.3.5. Eastern ocean near-boundary physics 95
4.3.6. Linking the coastal and equatorial low-frequency variability 95
4.3.7. Low-frequency reflection from non-meridional eastern ocean boundaries 97
4.3.8. Reflection of ENSO energy at the eastern Pacific Ocean boundary 100
References 102
Chapter 5 Wind-Forced Equatorial Wave Theory and the Equatorial Ocean Response to ENSO Wind Forcing 106
5.1. Overview 106
5.2. The Forced Wave Model 107
5.3. Solutions for General Low-Frequency Large-Scale Wind Forcing 112
5.4. Solutions for Idealized Forcing 114
5.4.1. Unbounded ocean, spatially constant wind – the Yoshida equatorial jet 114
5.4.2. The steady ocean response when the wind stress has no curl 115
5.5. Observed Low-Frequency Behavior of the Equatorial Pacific Sea Level and Thermocline 118
5.6. ENSO Equatorial Ocean Response due to the Wind Stress Curl 122
5.7. El Niño and Equatorial Kelvin Waves 126
5.8. Conclusion 127
References 128
Chapter 6 Sea Surface Temperature, Deep Atmospheric Convection and ENSO Surface Winds 130
6.1. Overview 130
6.2. Some Preliminaries 131
6.3. Equation of State 132
6.3.1. ‘Ideal’ gas 132
6.3.2. Dry air 132
6.3.3. Moist air 133
6.4. The First Law of Thermodynamics and Moist Static Energy 134
6.5. Sea Surface Temperature and Deep Atmospheric Convection 137
6.6. Heating and Vertical Velocity 140
6.7. Geopotential, Pressure Coordinates and the Continuity Equation 142
6.7.1. Geopotential and geopotential height 142
6.7.2. Horizontal gradients of F 144
6.7.3. The continuity equation in pressure coordinates 145
6.8. A Model of the Near-Surface Tropical Atmosphere’s Response to Large-Scale Convective Heating 146
6.8.1. Model formulation 147
6.8.2. Forced, damped equatorial long wave theory 150
6.8.3. ENSO wind anomalies and forced wave physics 152
6.8.4. Caveat 153
References 153
Chapter 7 ENSO Coupled Ocean–Atmosphere Models 156
7.1. Overview 156
7.2. Delayed Oscillator Theory 158
7.2.1. Introduction 158
7.2.2. Formulation of a warm pool displacement/delayed oscillator model of ENSO 159
7.2.3. Model solutions 161
7.2.4. The influence of other negative feedbacks 164
7.2.5. Non-constant . 165
7.3. Discharge–Recharge Oscillator Theory 166
7.3.1. Introduction 166
7.3.2. The atmosphere drives the ocean 166
7.3.3. Ocean dynamics and thermodynamics drive Tcen and the atmosphere 167
7.3.4. Mathematical solution and coupled physics 168
7.4. Intermediate Coupled Models 170
7.5. Conclusion 172
References 173
Chapter 8 Phase-Locking of ENSO to the Calendar Year 176
8.1. Overview 176
8.2. The Composite Warm ENSO Event 177
8.3. Phase-Locked ENSO Index Time Series 186
8.4. Phase-Locked Propagating Zonal Equatorial Wind Anomalies 190
8.5. Linking the Pacific Equatorial Wind Stress Anomalies with the SOI and NINO3.4 195
8.5.1. The relationship between the Southern Oscillation and zonal equatorial wind stress anomalies 196
8.5.2. The relationship between El Niño and the zonal equatorial wind stress 197
8.5.3. Phase-locked structure of NINO3.4 and the SOI 198
8.6. Phase-Locking and Biennial Variability 198
8.7. A Phase-Locking Mechanism for the Termination of ENSO Events 199
8.7.1. Basic mechanism 200
8.7.2. Large El Niños 201
8.8. Elements of a Seasonally Phase-Locked ENSO Mechanism 202
8.9. Concluding Remarks 203
References 203
Chapter 9 Upper Air Response to ENSO Heating and Atmospheric Teleconnections 206
9.1. Overview 206
9.2. Observations 207
9.3. Nearly Zonally Asymmetric ENSO Heating Anomalies 212
9.4. An Atmospheric ENSO Model 213
9.4.1. Logarithmic pressure coordinates 214
9.4.2. Equations of motion in logarithmic pressure coordinates 214
9.4.3. Model equations 216
9.4.4. Separation of the governing equations into vertical modes 218
9.4.5. Dominance of the first vertical mode 221
9.5. The Large Zonally Symmetric Air Temperature Response 223
9.6. Mid-latitude Zonally Symmetric Cooling During Warm ENSO Events 225
9.7. Zonally Asymmetric Mid-latitude Teleconnections 227
9.7.1. Introduction 227
9.7.2. Stationary Rossby wave theory 228
References 232
Chapter 10 ENSO Forecasting Using Dynamical Models 234
10.1. Overview 234
10.2. Smoothing, Bias Correction and Nudging 236
10.2.1. Smoothing 236
10.2.2. Bias correction 236
10.2.3. Nudging 238
10.3. The Kalman Filter 239
10.4. Adjoint Data Assimilation 242
10.5. Dynamical Model Forecast Performance 244
Appendix 10.A. Minimization of (10.15) 246
Appendix 10.B. Connecting Pa and Pf 247
References 248
Chapter 11 ENSO Forecasting Using Statistical Models 250
11.1. Overview 250
11.2. The Climatology and Persistence Forecasting Scheme 251
11.3. A Precursor ENSO Prediction Model 253
11.4. Prediction Using Canonical Correlation Analysis 255
11.4.1. The Basic Idea 256
11.4.2. Application of CCA to ENSO prediction 257
11.5. ENSO Prediction Using a Constructed Analogue Method 258
11.6. ENSO Prediction Using Linear Inverse Modeling 259
11.6.1. The basic theory 259
11.6.2. Model performance and ENSO dynamics 263
11.7. Comparison of Statistical and Dynamical ENSO Prediction Models 263
References 263
Chapter 12 ENSO’s Influence on Marine and Bird Life 266
12.1. Overview 266
12.2. El Niño’s Influence in the Eastern Equatorial Pacific 267
12.3. Peruvian Anchovies and Guano Birds 269
12.4. Zooplankton off California 273
12.4.1. Background 273
12.4.2. El Niño and California coastal waters 274
12.4.3. Rossby waves and ENSO currents off the California coast 275
12.4.4. Zooplankton population and El Niño 277
12.5. The Leaky Western Equatorial Pacific Boundary and Australian ‘Salmon’ 279
12.5.1. Physical background 279
12.5.2. The effect of coastal ENSO flow on western Australian salmon 281
12.6. Rock Lobsters and the Leeuwin Current off Western Australia 283
12.6.1. Physical background 283
12.6.2. The life cycle of the western rock lobster 285
12.6.3. Prediction of the rock lobster catch 286
12.6.4. Variations of the rock lobster catch and ENSO 286
12.7. Banana Prawns in the Gulf of Carpentaria 288
12.8. Green Turtles on the Great Barrier Reef 290
12.9. Tuna and the Movement of the Equatorial Pacific Warm Pool 292
12.10. Migration of the Black-Throated Blue Warbler 293
12.11. Concluding Remarks 296
References 296
Appendix A Empirical Orthogonal Function Analysis (Principal Component Analysis) 300
A.1. Basic Idea 300
A.2. The Higher Order EOFs and Their Principal Components 302
A.2.1. The EOFs are orthogonal 302
A.2.2. The principal components are uncorrelated 303
A.2.3. Representation of X(t) in terms of EOFs 303
A.2.4. Fraction of variance of the time series explained by the ith principal component 304
A.2.5. The meaning of the higher order EOFs 304
A.3. Physics and EOFs 305
References 306
Appendix B Canonical Correlation Analysis 308
B.1. Basic Idea 308
B.2. Canonical Correlation Pairs and Their Correlation Properties 311
B.3. The Meaning of the Higher Order Correlation Pairs 314
B.4. Prediction Y(t) from X(t) Using CCA 315
B.5. Use of Empirical Orthogonal Functions in CCA 316
B.6. Predicting Y(t) Using EOFs and CCA 317
Reference 317
Index 318