Meteorology of Tropical West Africa (eBook)
John Wiley & Sons (Verlag)
978-1-118-39127-3 (ISBN)
Meteorology of tropical West Africa: the Forecasters' Handbook presents the science and practice of weather forecasting for an important region of the tropics. Connecting basic theory with forecasting practice, the book provides a unique training volume for operational weather forecasters, and is also suitable for students of tropical meteorology.
The West African region contains a number of archetypal climatic zones, meaning that the science of its weather and climate applies to many other tropical regions. West Africa also exhibits some of the world's most remarkable weather systems, making it an inspiring region for students to investigate.
The weather of West Africa affects human livelihoods on a daily basis, and can contribute to hardship, poverty and mortality. Therefore, the ability to understand and predict the weather has the potential to deliver significant benefits to both society and economies.
The book includes comprehensive background material alongside documentation of weather forecasting methods. Many examples taken from observations of West African weather systems are included and online case-studies are referenced widely.
Douglas J Parker is the Met Office Professor of Meteorology at the University of Leeds.
Mariane Diop-Kane heads the Research and Development Department in the Senegalese weather service (ANACIM).
Meteorology of tropical West Africa: the Forecasters Handbook presents the science and practice of weather forecasting for an important region of the tropics. Connecting basic theory with forecasting practice, the book provides a unique training volume for operational weather forecasters, and is also suitable for students of tropical meteorology. The West African region contains a number of archetypal climatic zones, meaning that the science of its weather and climate applies to many other tropical regions. West Africa also exhibits some of the world s most remarkable weather systems, making it an inspiring region for students to investigate. The weather of West Africa affects human livelihoods on a daily basis, and can contribute to hardship, poverty and mortality. Therefore, the ability to understand and predict the weather has the potential to deliver significant benefits to both society and economies. The book includes comprehensive background material alongside documentation of weather forecasting methods. Many examples taken from observations of West African weather systems are included and online case-studies are referenced widely.
Douglas J Parker is the Met Office Professor of Meteorology at the University of Leeds. Mariane Diop-Kane heads the Research and Development Department in the Senegalese weather service (ANACIM).
Title Page 5
Copyright Page 6
Contents 7
Contributors 15
Preface 17
Acknowledgements 19
Acronyms 20
Chapter 1 Mean Climate and Seasonal Cycle 25
1.1 Introduction 25
1.2 Rainfall and Evaporation Climatologies 27
1.3 Water Vapour and Clouds 36
1.4 Radiation, Dust, Sunshine Duration, Vegetation and Soil Water 38
1.5 Pressure, Temperature, Humidity and Wind at the Surface 42
1.6 Upper Air Wind, Mass and Humidity Fields 46
1.6.1 An Eulerian Perspective on the Wind, Circulation and Dynamics 46
1.6.2 A Lagrangian Perspective on the Circulation 53
1.7 Summary Schematics of the January and July West African Monsoon System 57
Acknowledgements 60
Appendix: Acronyms 61
Notes 61
References 62
Chapter 2 Synoptic Systems 64
2.1 Scientific Background 64
2.1.1 Introduction 64
2.1.2 Continental-scale Synoptic Features 65
2.1.2.1 Saharan Heat Low 65
2.1.2.2 The Intertropical Discontinuity or Intertropical Front 67
2.1.2.3 African Easterly Jet 68
2.1.3 African Easterly Waves 69
2.1.3.1 Background 69
2.1.3.2 Observed Synoptic Structure of African Easterly Waves, Analyses and Statistical Composites 69
2.1.3.3 African Easterly Wave Structure 75
2.1.3.4 African Easterly Wave Genesis 79
2.1.3.5 African Easterly Wave Dynamics and Evolution 80
2.1.3.6 Relationship with Deep Convection 83
2.1.3.7 Downstream Transformation 84
2.1.4 Mid-latitude Troughs and Upper-level Troughs 86
2.1.5 Extratropical Dry Air Intrusions 89
2.1.6 Guinea Coast Systems 90
2.1.6.1 Guinea Coast Cloud and Rainfall 90
2.1.6.2 The Little Dry Season 92
2.1.7 Synoptic-scale Land-surface Feedbacks 93
2.2 Operational Methods and Canonical Synoptic Patterns 95
2.2.1 Synoptic Fields and Main Inferences 95
2.2.2 African Easterly Wave Case Studies and Canonical Structures 96
2.2.2.1 An Archetypal African Easterly Wave Event: Case Study CS024, 12–16 August 2012 96
2.2.2.2 African Easterly Wave Breaking Events 97
2.2.2.3 Coastal Development of African Easterly Waves 99
2.2.3 Dry-season Thunderstorms in West Africa 103
Acknowledgements 107
Appendix: Acronyms 107
Notes 108
References 108
Chapter 3 Deep Convection 114
3.1 Scientific Background 114
3.1.1 Introduction 114
3.1.1.1 Is Convection Different over Africa? 115
3.1.1.2 Interaction between convection and the larger scale flow 116
3.1.1.3 Aims of this chapter 118
3.1.2 Processes and Factors Governing Convection 118
3.1.2.1 Convective updraughts 118
3.1.2.2 Downdraughts, Downdraught Available Convective Potential Energy and Density Currents 120
3.1.2.3 Wind Shear 124
3.1.2.4 Discussion 124
3.1.3 Organisation of Deep Convection 126
3.1.3.1 Different Types of Organisation 126
3.1.3.2 The Squall-line Conceptual Model 128
3.1.3.3 Climatology and Classification of Mesoscale Convective Systems 129
3.1.4 Life Cycle and Diurnal Cycle 132
3.1.4.1 Triggering 132
3.1.4.2 The Diurnal Cycle 137
3.1.4.3 Dissipation 138
3.2 Operational Methods 139
3.2.1 Life Cycle of Convection on 12–16 August 2012 (CS02) 141
3.2.1.1 MCS1 141
3.2.1.2 MCS2 141
3.2.1.3 MCS3 141
3.2.1.4 CS1 141
3.2.1.5 CS2 143
3.2.1.6 Suppressed Convection 143
3.2.2 A Cold Pool Case Study, 27 September 2014 (CS14) 143
3.2.3 Forecasting Areas of Storm Initiation or Suppression 146
3.2.3.1 Synoptic Conditions and Stability 146
3.2.3.2 History of Recent Storms 149
3.2.3.3 Use of Numerical Weather Prediction to Forecast Convective Initiation 149
3.2.4 Forecasting Storm Types 149
3.2.4.1 Organisation, Longevity, Speed and Direction 149
3.2.4.2 Weather Phenomena 149
3.2.5 Forecasting Suppression of Convection 150
Acknowledgements 151
Appendix: Acronyms 151
Notes 151
References 151
Chapter 4 Local Weather 154
4.1 Scientific Background 154
4.1.1 Introduction 154
4.1.2 The Surface Energy Balance and the Atmospheric Surface Layer 155
4.1.2.1 Surface Energy Balance Principles 155
4.1.2.2 Surface?layer Winds 158
4.1.2.3 The Surface Energy Balance over West African Climatic Zones 159
4.1.2.4 Variation of Surface Energy Balance and Surface Temperatures in Response to Physical Processes 159
4.1.3 Boundary Layer over West Africa: Diurnal Cycle 162
4.1.3.1 Daytime Convective Boundary Layer 162
4.1.3.2 Night-time Planetary Boundary Layer 166
4.1.3.3 Fog Formation 170
4.1.3.4 Marine Planetary Boundary Layer 171
4.1.4 Local Winds: Mesoscale Variability and Circulations 171
4.1.4.1 Coherent Structures in the Winds: Convergence Lines and Gravity Currents 172
4.1.4.2 The Sea Breeze and the Land Breeze 175
4.1.4.3 Topographically Forced Winds 178
4.1.4.4 Local Winds and Convergence Associated with Soil Moisture and Vegetation Boundaries 179
4.1.4.5 Trapped Waves, Bores and Solitary Waves 180
4.1.5 Convective Rainfall Distribution on the Local Scale 181
4.1.5.1 Cumulus Congestus Clouds 181
4.1.5.2 Land Surface Controls on Rainfall: Soil Moisture and Vegetation 182
4.1.6 Marine Weather 184
4.2 Operational Methods 184
4.2.1 Forecasting of Maximum and Minimum Temperatures (Tx, Tn) 184
4.2.1.1 Statistically Based Forecasts 185
4.2.1.2 Physical Methods Based on Sounding Data 186
4.2.1.3 Integration with Numerical Weather Prediction Data 188
4.2.1.4 Physical Processes Influencing Daily Temperatures 188
4.2.2 Visibility 188
4.2.2.1 Basic Principles of Visibility Forecasting 188
4.2.2.2 Fog Forecasting 190
4.2.3 Forecasting Wind Shear and Turbulence 192
4.2.4 Forecasting Land, Sea and Lake Breezes 193
4.2.5 Marine Forecasting 193
4.2.5.1 Winds over the Sea 193
4.2.5.2 Ocean Waves 193
4.2.5.3 Visibility over the Sea 194
4.2.6 Marine Services 195
4.2.6.1 Forecasts/Warnings 195
4.2.6.2 Routeing of Ships 195
Acknowledgements 195
Appendix: Acronyms 196
Notes 196
References 196
Chapter 5 Dust 199
5.1 Scientific Background 199
5.1.1 The Dust Cycle 199
5.1.1.1 Emission 199
5.1.1.2 Transport 201
5.1.1.3 Wet and Dry Deposition 201
5.1.2 Meteorological Systems 203
5.1.3 Climatologies 206
5.1.4 Interactions with Weather and Climate 208
5.1.4.1 Direct Radiative Effect 208
5.1.4.2 Impact on Atmospheric Stability 208
5.1.4.3 Impact on Cloud Microphysics 210
5.1.4.4 Fertilisations of Ecosystems by Dust 210
5.2 Operational Methods 212
5.2.1 Introduction and Structure 212
5.2.2 Data 212
5.2.2.1 Surface Station Data 212
5.2.2.2 Surface and Pressure?level Charts 212
5.2.2.3 Remote Sensing 212
5.2.2.4 Numerical Model Predictions of Dust 215
5.2.3 Practical Guidelines for Forecasters 218
5.2.3.1 Introduction 218
5.2.3.2 Forecasting Harmattan Dust Haze 218
5.2.3.3 Forecasting Convective Dust Storms 222
5.2.4 Case Study Examples Online 223
Appendix: Acronyms 223
Notes 224
References 224
Chapter 6 Nowcasting 228
6.1 Scientific Background 228
6.1.1 Introduction 228
6.1.2 Nowcast Process 229
6.1.2.1 Convective Weather Outlook 229
6.1.2.2 Conceptual Models and Climatology 230
6.1.2.3 Stability Analyses 233
6.1.2.4 Storm Type 239
6.1.2.5 Extrapolation of Existing Storms 239
6.1.2.6 Nowcasting Storm Initiation and Evolution 241
6.2 Operational Methods for Nowcasting Severe Weather 245
6.2.1 Thunderstorms, Hail and Flash Floods 248
6.2.2 Procedure for Nowcasting Thunderstorms, Hail and Flash Floods 248
6.2.3 Wind Shear 258
6.2.4 Procedure for Nowcasting Wind Shear 259
6.2.5 Lightning 270
6.2.6 Procedure for Nowcasting Lightning 272
Appendix A: Acronyms 274
Appendix B: Checklist for Improving Operational Nowcasting Capability 274
Appendix C 275
Appendix D: Online Web Sites Containing Weather-related Training Materials 276
Note 276
References 276
Chapter 7 Subseasonal Forecasting 279
7.1 Scientific Background? 279
7.1.1 Introduction 279
7.1.2 Data 280
7.1.2.1 Precipitation 280
7.1.2.2 Sea Surface Temperature 280
7.1.2.3 Outgoing Longwave Radiation 282
7.1.2.4 Brightness Temperature 282
7.1.2.5 Reanalysis 282
7.1.3 Detection of the Main Modes of Subseasonal Variability of Convection 282
7.1.4 Convectively Coupled Equatorial Waves 284
7.1.4.1 Kelvin Waves 287
7.1.4.2 Equatorial Rossby Waves 287
7.1.4.3 Mixed Rossby–Gravity Waves 288
7.1.5 Other Convectively Coupled Signals and Links with Equatorial Waves 289
7.1.5.1 Signals Between 10 and 25 Days 289
7.1.5.2 Periodicities Between 25 and 90 Days and the Madden–Julian Oscillation 293
7.1.6 Mechanisms for Dry? and Wet?spell Frequency 296
7.1.7 Onset of the Monsoon and Rainfall 299
7.1.7.1 Detection 299
7.1.7.2 Mechanisms 300
7.1.7.3 Applications 300
7.1.7.4 Summary and Outlook 301
7.2 Operational Methods 301
7.2.1 Prediction Tools 303
7.2.1.1 Madden–Julian Oscillation Predictions 303
7.2.1.2 Prediction of Regional Climate Anomalies 304
7.2.2 Guidelines for Operational Forecasting 304
7.2.2.1 State of the Madden–Julian Oscillation 304
7.2.2.2 Consensus Outlooks 307
7.2.2.3 Forecast Verifications 308
Acknowledgements 309
Appendix: Acronyms 309
Note 309
References 310
Chapter 8 Seasonal Forecasting 313
8.1 Scientific Background 313
8.1.1 Introduction 313
8.1.2 Sea Surface temperature teleconnections 315
8.1.3 Statistical forecasts 317
8.1.3.1 Methods 317
8.1.3.2 Representation of predictors: sea surface temperature empirical orthogonal function predictors 321
8.1.3.3 Representation of predictands 324
8.1.3.4 Assessment of statistical methods 327
8.1.3.5 Performance over 1996–2009 328
8.1.4 Dynamical forecasts 329
8.1.4.1 Performance over 1996–2009 329
8.1.4.2 Correction of systematic errors in models 330
8.1.4.3 Future models: potential for improving seasonal forecasts 333
8.1.4.4 Long-lead predictability 335
8.1.5 Combined forecasts 335
8.1.5.1 Performance over 1996–2009 336
8.1.6 Other variables and seasons 337
8.1.6.1 Prediction of outflow from Lake Volta 337
8.1.6.2 Prediction of meningococcal meningitis in the West Africa dry season 337
8.1.6.3 Applying seasonal forecasts to assist agriculture in Sénégal 340
8.2 Operational Methods 340
8.2.1 International seasonal forecast web sites: sources of information 340
8.2.1.1 World Meteorological Organization Lead centre multimodel ensemble web site 340
8.2.1.2 Long-range forecast verifications 341
8.2.1.3 UK Met Office web site 341
8.2.1.4 ECMWF/EUROSIP web site 341
8.2.1.5 NOAA/NCEP web site 341
8.2.1.6 International Research Institute for Climate and Society seasonal forecast web site 341
8.2.1.7 African Center of Meteorological Application for Development web site 342
8.2.2 Consensus forecasts 342
8.2.2.1 The PRESAO process 342
8.2.2.2 Assessment of PRESAO forecasts 1998–2007 342
8.2.3 Software and tools 342
8.2.3.1 The Climate Predictability Tool 343
8.2.3.2 International Research Institute for Climate and Society data library 343
8.2.3.3 KNMI Climate Explorer 343
8.2.3.4 NOAA Earth System Research Laboratory interactive web site 343
8.2.4 Other web sites Including Forecast Applications 343
8.2.4.1 FEWS NET 343
8.2.4.2 AGRHYMET, Niger 343
8.2.5 Hints and recommendations 344
Appendix A: Acronyms 344
Appendix B: Empirical Orthogonal Functions 344
Note 345
References 345
Chapter 9 Remote Sensing 347
9.1 Scientific Background 347
9.1.1 The Global Satellite Observing System 347
9.1.1.1 Orbital Geometry 347
9.1.1.2 Advantages and Limitations of Geosynchronous and Low-earth-orbit Satellites 349
9.1.1.3 Scanning and Viewing Geometry 349
9.1.2 Scientific Basis of Remote Sensing 349
9.1.2.1 Electromagnetic Spectrum 349
9.1.2.2 Radiance and Blackbody Radiation 350
9.1.2.3 Radiative Transfer 351
9.1.2.4 Reflectance 354
9.1.2.5 Passive and Active Remote Sensing 355
9.1.3 Spectral Bands or Channels 355
9.1.3.1 Visible and Infrared Channels 355
9.1.3.2 Microwave Channels 355
9.1.4 Multispectral Analysis: Visualised Products 357
9.1.4.1 Classification Using Individual Channels 358
9.1.4.2 Differencing or Ratio of Two Channels 358
9.1.4.3 Quantitative Feature Extraction 358
9.1.4.4 RGB Products 358
9.1.4.5 Blended or ‘Sandwich’ Image Products 366
9.1.5 Satellite Retrieval of Meteorological Parameters 366
9.1.5.1 Water Vapour 367
9.1.5.2 Vertical Structure of Temperature, Humidity and Winds 368
9.1.5.3 Clouds 371
9.1.5.4 Precipitation 376
9.1.5.5 Dust 377
9.1.5.6 Fire, Smoke and Haze 377
9.1.5.7 Volcanic Ash 379
9.1.5.8 Lightning 381
9.1.5.9 Surface Wetness and Vegetation 381
9.1.5.10 Ocean Surface Winds 382
9.1.6 Weather Radar 382
9.1.6.1 Weather Radar Basics 382
9.1.6.2 Ground and Satellite Weather Radar Products 386
9.1.6.3 Wind Profilers 386
9.2 Operational Methods 386
9.2.1 Platforms and Sensors 388
9.2.1.1 Geostationary Satellites and Sensors 388
9.2.1.2 Low-earth-orbiting Satellites 388
9.2.1.3 Satellite Operational Analysis Tools and Products 391
9.2.1.4 Radar Operational Analysis Tools 391
9.2.2 Large-scale Feature Identification 391
9.2.2.1 Intertropical Discontinuity and Intertropical Convergence Zone 391
9.2.2.2 Subseasonal Circulations: Madden–Julian Oscillation, Equatorial Waves 391
9.2.2.3 Synoptic Systems 391
9.2.3 Mesoscale and Local?scale Analysis 391
9.2.3.1 Mesoscale Circulations 391
9.2.3.2 Mesoscale Convective Systems 393
9.2.3.3 Dust and Sand Storms 394
9.2.3.4 Convective Cells, Outflow Boundaries, Cloud Lines 394
9.2.4 Fog and Low Stratus 394
9.2.5 Satellite Soundings 394
9.2.6 Winds 394
9.2.7 Aviation Hazards 394
9.2.8 Marine Analysis 396
9.2.9 Sources of Satellite Products 396
9.3 Case Study, Presentations and Other Resources 397
9.3.1 Radar and Satellite Analysis 397
9.3.1.1 Mesoscale Convective Systems and an African Easterly Wave 397
9.3.1.2 Tropical Cyclone, Undular Bore and Other Cloud Systems 397
9.3.2 Presentations 401
9.3.3 Education and Training 402
Appendix: Acronyms 402
References 402
Chapter 10 Numerical Weather Prediction over Africa 404
10.1 Scientific Background 404
10.1.1 Introduction 404
10.1.2 Deterministic Numerical Weather Prediction Systems 406
10.1.2.1 Observations 406
10.1.2.2 Data Assimilation 411
10.1.2.3 Global and Regional Numerical Weather Prediction Models 413
10.1.2.4 Convective-scale Models 418
10.1.2.5 Model Output Statistics 419
10.1.3 Ensemble Prediction and Atmospheric Predictability 419
10.1.4 Summary and Future Capability 420
10.2 Operational Numerical Weather Prediction over Africa 421
10.2.1 Current Capability of Deterministic Numerical Weather Prediction Forecasts 421
10.2.1.1 Precipitation and Moisture Budget in Numerical Weather Prediction Models and Analyses 421
10.2.1.2 Near-surface Temperatures and Humidities 429
10.2.1.3 Low-level Monsoon Flow and Saharan Heat Low 431
10.2.1.4 African Easterly Jet 434
10.2.1.5 African Easterly Waves 434
10.2.2 Predicting Severe Weather and Modelling Uncertainty 437
10.2.2.1 Ensemble Forecasts from Deterministic Predictions 438
10.2.2.2 World Meteorological Organization Severe Weather Forecast Demonstration Project 439
10.2.2.3 Convective (Kilometre)-scale Modelling 440
Acknowledgements 443
Appendix: Acronyms 443
Notes 443
References 443
Chapter 11 West African Synthetic Analysis and Forecast: WASA/F 447
11.1 Introduction 447
11.2 The intertropical discontinuity/ intertropical front, or intertropical boundary in Ghana 449
11.2.1 Main characteristics 450
11.2.2 Drawing Rules 450
11.2.3 Specific Cases 450
11.3 The Heat Low or Thermal Depression 450
11.3.1 Main Characteristics 450
11.3.2 Drawing rules 452
11.4 The Subtropical Jet 453
11.5 Features Associated with Mid?latitudes 454
11.6 Mid-level Dry Air 455
11.6.1 Main Characteristics 455
11.6.2 Drawing Rules 455
11.7 The Tropical Easterly Jet 455
11.7.1 Main Characteristics 455
11.7.2 Drawing Rules 457
11.8 The African Easterly Jet 457
11.8.1 Main Characteristics 457
11.8.2 Drawing Rules 457
11.9 African Easterly Waves and Cyclonic Vortices 459
11.9.1 Main characteristics 459
11.9.2 Drawing rules 461
11.10 The African Monsoon Layer and the Monsoon Trough 465
11.10.1 Main Characteristics 465
11.10.2 Drawing Rules 465
11.11 Dust or sand 468
11.12 Convection 468
11.12.1 Analysis of the convective activity 469
11.12.2 Forecast Rules and Required Diagnostics for Convection 469
Appendix: Acronyms 475
Notes 475
References 475
Index 476
EULA 493
| Erscheint lt. Verlag | 13.2.2017 |
|---|---|
| Sprache | englisch |
| Themenwelt | Naturwissenschaften ► Geowissenschaften ► Meteorologie / Klimatologie |
| Technik | |
| Schlagworte | Acronyms • African • contributors • convection • Deep • earth sciences • Foreword • Geowissenschaften • january • Meteorologie • meteorology • Methods • monsoon • operational methods • operational methods local • Patterns • schematics • sensing • subseasonal • Surface • Synoptic • System • Systems • Weather |
| ISBN-10 | 1-118-39127-6 / 1118391276 |
| ISBN-13 | 978-1-118-39127-3 / 9781118391273 |
| Informationen gemäß Produktsicherheitsverordnung (GPSR) | |
| Haben Sie eine Frage zum Produkt? |
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