Coastal Altimetry (eBook)

Coastal Altimetry 2
Copyright Page 3
Preface 4
Editorial Note and Acknowledgements 8
Contents 10
1: Radar Altimetry: Past, Present and Future 12
1.1 The Principle of Radar Altimetry 14
1.2 The Pioneering Era 15
1.3 The Historical Era 15
1.4 The Present Epoch 17
1.5 The Future 18
1.5.1 CryoSat-2 Mission Data Sheet 20
1.5.2 Sentinel-3 Mission Data Sheet 20
1.5.3 SARAL Radar Altimeter Mission Data Sheet 20
1.5.4 HY-2 Radar Altimeter Mission 24
1.6 Conclusions and Perspectives 25
References 26
2: From Research to Operations: The USDA Global Reservoir and Lake Monitor 29
2.1 The USDA/FAS Decision Support System 31
2.2 Satellite Radar Altimetry 32
2.3 The Creation and Implementation of the GRLM 34
2.4 Satellite Data Sets 34
2.5 Technique 35
2.6 Jason-1 Data Loss 38
2.7 Preliminary Benchmarking and Product Validation 39
2.8 T/P and Jason-1 Product Revision 42
2.9 GFO Products and Further Validation 43
2.10 Program Limitations 47
2.11 Products and Applications 48
2.12 Current Status 52
2.13 Phase IV Tasks 53
2.14 Anticipated Phase IV Results 54
2.15 Summary, Recommendations and Future Outlook 56
References 58
3: User Requirements in the Coastal Ocean for Satellite Altimetry 61
3.1 Introduction 62
3.2 Methodology to Infer the User Requirements 63
3.3 Coastal Altimetry Users’ Profile 64
3.4 Physical Requirements 65
3.5 Requirements in Accuracy and Precision 67
3.6 Requirements in Data Format and Delivery Mode 68
3.7 Conclusion 68
References 70
4: Retracking Altimeter Waveforms Near the Coasts 71
4.1 Introduction 73
4.2 A Brief Introduction to Satellite Altimetry, On-board Trackers and Waveform Retracking 74
4.2.1 Basic Principles of Altimetry 74
4.2.2 Trackers and Retrackers 77
4.3 The Shape of Altimeter Waveforms in the Coastal Zone 78
4.3.1 The Effect of Land on Coastal Waveforms 78
4.3.2 Envisat RA-2 Waveforms in Coastal Areas 79
4.3.3 Jason-1 and Jason-2 Waveforms in Coastal Areas 81
4.3.4 ERS-2 Waveform Shapes Over Australian Coasts 82
4.3.5 Coastal Waveform Classification 82
4.4 Empirical Retrackers 85
4.4.1 Offset Centre of Gravity Retracker (OCOG) 85
4.4.2Threshold Retracker 86
4.4.3Improved Threshold Retracker 87
4.4.4The b-parameter Retracker 89
4.5Physically-based Retrackers 91
4.5.1The Brown-Hayne Theoretical Ocean Model 91
4.5.2The NOCS Non-linear Ocean Retracker 93
4.5.3Practical Implementations of the Brown-Hayne Ocean Retracker 95
4.6Statistical Methods of Function Fitting 95
4.6.1Maximum Likelihood Estimator (MLE) 96
4.6.2Weighted Least Square Estimator (WLS) 96
4.6.3Unweighted Least Square Estimator 97
4.7Applications of Waveform Retracking to Coastal Waveforms 98
4.7.1The CNES/PISTACH Coastal Processing System for Jason-2 98
4.7.2The COASTALT Processing System for Envisat RA-2 100
4.7.3Coastal Retracking Around Australia 101
4.7.3.1Iteratively Reweighted Least-squares Procedure 101
4.7.3.2Application of Iteratively Reweighted Least-squares Fitting to ERS-2 and Jason-1 Coastal Waveforms 103
4.7.4Application of Empirical Retrackers to Envisat RA-2 in the Mediterranean Sea 104
4.8Innovative Retracking Techniques 104
4.8.1Iterative Retracking 106
4.8.2Multiple-waveform Retracking 106
4.9Conclusions 107
References 109
5: Range and Geophysical Corrections in Coastal Regions: And Implications for Mean Sea Surface Determination 112
5.1 Introduction 113
5.2 Sea Level Anomalies 117
5.3 Altimetric Sea Level Corrections 118
5.4 Dry Troposphere Refraction 120
5.5 Wet Troposphere Refraction 122
5.6 Ionosphere Refraction 125
5.7 Sea-State Bias Correction 130
5.8 Tide Corrections 133
5.8.1 Ocean Tide 134
5.8.2 Solid Earth Tide Correction 137
5.8.3 Pole Tide Correction 137
5.9 Dynamic Atmosphere Correction 138
5.10 Geoid and Mean Sea Surface Models 141
5.11 Reference Frame Offsets 143
5.12 Range Corrections and Mean Sea Surface Determination 143
5.13 Summary 150
References 151
6: Tropospheric Corrections for Coastal Altimetry 155
6.1Introduction 156
6.2Combination and Processing of Available Information 157
6.2.1Dynamically Linked Model Approach 158
6.2.2GNSS-derived Path Delay Method 160
6.2.2.1Determination of Tropospheric Path Delays at GNSS Stations 161
6.2.2.2Comparison of GNSS-derived Tropospheric Fields with GDR Corrections 162
6.2.2.3Data Combination Methodology 166
6.3Brightness Temperature Contamination and Correction 170
6.3.1Instrumental Configuration and Reference Field 171
6.3.2An Analytical Correction of TBs: The “erf Method” 172
6.3.2.1Improved Method 172
6.3.2.2Sensitivity to Errors in q or in TBland and TBsea 174
6.3.3Using the Proportion of Land in the Footprint 175
6.3.3.1Description of the Proportion Method 175
6.3.3.2Performance of the Method over Simulated Data 176
6.3.4Performance Analysis over Real Measurements 176
6.3.5Discussion 178
6.4Dry Tropospheric Correction 178
6.5Conclusions and Perspectives 180
References 182
7: Surge Models as Providers of Improved “Inverse Barometer Corrections” for Coastal Altimetry Users 185
7.1 Introduction 186
7.2 Sea Level Variability due to Meteorological Forcing in the Deep Ocean and Coastal Seas 187
7.3 Regional Storm Surge Models 188
7.4 Global Barotropic Models 193
7.5 COASTALT Validation Tests 194
7.6 Conclusions 195
References 196
8: Tide Predictions in Shelf and Coastal Waters: Status and Prospects 198
8.1 Introduction 199
8.2 Tide Prediction in Shallow Water 200
8.2.1 Nonlinearity 201
8.2.2 Temporal Variability 204
8.2.3 Summary 206
8.3 Assessment of Selected Global Models 207
8.3.1 Example Regional Assessment: Gulf of Maine 210
8.4 Along-track Tide Corrections 211
8.5 Data Assimilation: Northern Australia 213
8.6 Prospects 218
8.7 Appendix 219
References 220
9: Post-processing Altimeter Data Towards Coastal Applications and Integration into Coastal Models 224
9.1 Introduction 226
9.2 Post-processing Altimetry in Coastal Zones: Early Developments 227
9.2.1 Redefining Editing Strategies 228
9.2.2 Improving De-aliasing Corrections 229
9.2.3 Improving the Vertical Reference Frame 232
9.3 Latest Upgrades of the X-TRACK Processor 234
9.3.1 Orbit and Large-Scale Error Reduction 235
9.3.2 High Rate Data Stream 236
9.4 Matching Satellite Altimetry with Coastal Circulation Models 237
9.4.1 Rationale 237
9.4.2 Consistency Between Altimeter Measurements and Model Estimates 239
9.4.2.1 Steric Effect Surface Signature 239
9.4.2.2 Steric Height in Coastal Ocean Models 240
9.4.3 Methodologies and Case Studies 241
9.4.3.1 Modelling Approach 242
Strategy 242
Model Data 243
Coastal Altimeter Data 243
Results and Analysis 244
9.4.3.2 Statistical Approach 246
Methodology 246
Case Study 247
9.5 Concluding Remarks and Perspectives 248
References 250
10: Coastal Challenges for Altimeter Data Dissemination and Services 254
10.1 Introduction 255
10.2 Generating Custom Products 257
10.3 Coastal Altimetry Integration in Data Systems 259
10.4 Implications for Data Products and Systems 260
10.4.1 Standard Formats 260
10.4.2 Metadata Tracking 260
10.4.3 Data Distribution Tools 261
10.4.4 Data Service Solutions 261
10.5 A Vision for a Coastal Data Service 262
References 264
11: In situ Absolute Calibration and Validation: A Link from Coastal to Open-Ocean Altimetry 265
11.1 Introduction 267
11.1.1 Overview 267
11.1.2 A Review of Absolute Calibration Experiments 269
11.1.3 Absolute Versus Relative Calibration 270
11.1.4 Outline 271
11.2 Calibration Geometry and Measurements 271
11.2.1 Absolute Calibration Techniques 271
11.2.2 Formation Flying and Tandem Mission Verification 274
11.2.3 In situ Measurements 274
11.2.3.1 Sea Surface Heights 274
11.2.3.2 Significant Wave Height 277
11.2.3.3 Range Comparison 278
11.2.3.4 Wet Tropospheric Correction 278
11.2.3.5 Local Weather Conditions 279
11.2.4 Geophysical Corrections 279
11.2.5 Reference Frames 280
11.2.6 Orbit 281
11.3 Dedicated Calibration Sites 281
11.3.1 Overview 281
11.3.2 Harvest 282
11.3.3 Corsica 284
11.3.4 Bass Strait 287
11.3.5 Data Analysis Comparison 289
11.4 Salient Results 289
11.4.1 Detection of Instruments/Model Problems 289
11.4.1.1 JMR and Orbit impact on Jason-1 GDR-A products 291
11.4.1.2 Radiometer Behavior Close to the Coast 293
11.4.2 Recent Results 295
11.4.3 Revised Error Budget in Altimetry 296
11.5 Conclusion 298
References 299
12: Introduction and Assessment of Improved Coastal Altimetry Strategies: Case Study over the Northwestern Mediterranean Sea 303
12.1 Introduction 305
12.2 Study Area Characteristics 308
12.3 Main Characteristics of Existing Data 310
12.3.1 Standard Data: AVISO Along-track Data 310
12.3.2 Improved Pre-processed Data: RECOSETO Data 310
12.3.3 Improved Post-processed Data: X-TRACK Data 311
12.4 Benefit of Improved Strategies over the Northwestern Mediterranean Sea 312
12.4.1 Improvements from RECOSETO Project 312
12.4.1.1 Methods and Data Used 312
12.4.1.2 Wet tropospheric Correction 313
12.4.1.3 Distance Analysis of T/P and Envisat Measurements 314
12.4.1.4 Improved Retracking 315
12.4.2 Improvements from X-TRACK Processor 316
12.4.2.1 Methods and Data Used 316
12.4.2.2 Improved Space-Time Resolution 317
12.4.2.3 Improved Data Editing and Correction Rebuilding 318
12.4.2.4 Improved de-aliasing corrections by using regional modelling 320
12.4.2.5 Improved Multi-satellite Data Sets 322
12.4.2.6 Improved Mean Sea Level Computation 322
12.5 Intercomparison Experiments: X-TRACK-SLA Versus DT-SLA “Upd” 323
12.5.1 Basin Scale Statistics 323
12.5.1.1 Data Availability in Coastal Area 323
12.5.1.2 Altimetric Data Quality 324
12.5.2 Focus on the Gulf of Lion 326
12.5.2.1 Statistical Intercomparisons 326
12.5.2.2 Application: Monitoring of the LPC Current 329
12.6 Conclusion, Ongoing Work, and Perspectives 331
References 333
13: Satellite Altimetry Applications in the Caspian Sea 337
13.1 Introduction 339
13.2 Caspian Sea Level Variability and Its Observations by Level Gauges 342
13.3 Application of Satellite Radar Altimetry for the Caspian Sea 344
13.3.1 Tides and Atmospheric Forcing 345
13.3.2 Atmospheric Corrections 345
13.3.3 Mean Sea Surface 345
13.3.4 Influence of Ice Cover on Altimetric Measurements 347
13.3.5 Multi-satellite Bias 348
13.3.6 Calibration/Validation (Cal/Val) Activities 348
13.3.7 Existing Datasets 351
13.4 Results 352
13.4.1 Seasonal Variability of the Caspian Sea Level/Volume 352
13.4.2 Storm Surges in Altimetry 354
13.4.3 Volga Water Level from Altimetry 357
13.4.4 Water Budget of the Caspian Sea and the Kara-Bogaz-Gol Bay 358
13.4.5 Wind and Wave Regime 360
13.4.6 Ice Cover Regime 363
13.5 Discussion and Conclusions 366
References 368
14: Satellite Altimetry Applications in the Black Sea 373
14.1 Introduction 374
14.2 Physical Processes in the Coastal Zone 375
14.3 Sea Level Measurements 377
14.3.1 Long-Term Variability of Sea Level 377
14.3.2 Eddy Dynamics 379
14.3.3 Correspondence Between Altimeter-Derived and In situ Data on Sea Level 381
14.4 Wind Speed Measurements 384
14.5 Conclusions 390
References 392
15: Satellite Altimetry Applications in the Barents and White Seas 394
15.1 Introduction 395
15.2 Calibration/Validation of Satellite Altimetry Measurements 400
15.2.1 Wind Speed 401
15.2.2 Sea Surface Height 405
15.2.3 Tidal Models 409
15.3 Long-Term Variability of Sea Level 411
15.4 Interannual Variability of Sea Ice Edge Position 416
15.5 Conclusions 418
References 418
16Satellite Altimetry Applications off the Coasts of North America 421
16.1 Background 422
16.2 East Coast of North America 423
16.2.1 The Labrador Sea and Coastal Eastern Canada 423
16.2.2 The Scotian Shelf and the North Atlantic Bight 425
16.3 The Gulf of Mexico and Caribbean Sea 429
16.4 West Coast of North America 433
16.4.1 California Current System 435
16.4.1.1 Ageostrophic Currents in the California Current System 443
16.4.1.2 Numerical Modeling of the Structure and Dynamics of the California Current System 444
16.4.1.3 Numerical Modeling of the Southern California Bight and Comparisons with Satellite Altimetry Data 446
16.5 Alaskan Stream 447
16.6 Tidal Energy in the Bering Sea 451
16.7 Future Work 452
References 452
17: Evaluation of Retracking Algorithms over China and Adjacent Coastal Seas 456
17.1 Introduction 457
17.2 Data Set 460
17.3 Waveform Analysis 461
17.3.1 Ocean to Land 461
17.3.2 Land to Ocean 463
17.4 Retracking Algorithms 464
17.4.1 Inter-comparison of Jason-1 SLA at Crossover Points 464
17.4.2 Jason-1 Ground Comparison of SSH 466
17.4.3 Jason-1 Ground Comparison of SWH 469
17.5 Conclusions and Perspectives 472
References 473
18: Satellite Altimetry for Geodetic, Oceanographic, and Climate Studies in the Australian Region 475
18.1 Introduction 477
18.2 The Coastal Currents Around Australia 477
18.2.1 Surface Geostrophic Currents 478
18.2.1.1 Seasonal Sea Level Anomalies 478
18.2.1.2 Absolute Mean Sea Level Topography 479
18.2.1.3 Surface Current Fields 479
18.2.2 Annual Cycle of Currents Along Southern Australia 481
18.2.3 Transport of the EAC from Altimetry 483
18.2.4 Net Transport 484
18.2.5 Transport Along the Section 484
18.3 Mapping Coastal Ocean Currents Using Altimetry, Tide Gauges, Drifters, and Thermal Imagery 486
18.3.1 Coastal Sea Level Mapping 486
18.3.2 Coastal Dynamics 487
18.4 Sea level Rise 490
18.4.1 Global and Coastal Sea level Rise 490
18.4.1.1 Global Averaged Sea level Rise 490
18.4.1.2 Coastal and Global Averaged Sea level Rise 492
18.4.1.3 Recent Sea level Rise in the Australian Region 492
18.4.2 Implications for Understanding Coastal Sea level Rise 494
18.5 The Role of Satellite Altimetry in Determining the Australian Marine Gravity Field 495
18.5.1 How Accurate are Altimeter Data near the Australian Coast? 496
18.5.1.1 Altimeter Coastal-contaminated Distance Around Australia 496
18.5.1.2 Coastal Retracking System for Altimeter Waveforms 497
18.5.2 Using Altimetry to Detect Ship-track Gravity Data Errors 500
18.5.3 Assessment of AUSGeoid98 offshore of Western Australia 503
18.6 Conclusions and Perspectives 505
References 506
19: Lakes Studies from Satellite Altimetry 511
19.1 Altimetry Over Lakes 512
19.2 Lakes and Climate Change 515
19.3 Andean Lakes 517
19.4 East African Lakes 521
19.4.1 Climate Change and the East African Lakes 521
19.4.2 Lake Victoria 523
19.5 Central Asian Lakes 527
19.6 Conclusions 531
References 532
20: The Future of Coastal Altimetry 536
20.1 Introduction 537
20.1.1 Initial Conditions 538
20.1.2 The Challenge 539
20.1.3 New Technologies 540
20.2 AltiKa 540
20.2.1 Introduction 540
20.2.2 Key Innovations 541
20.2.2.1 Bandwidth 541
20.2.2.2 Beamwidth 542
20.2.2.3 Pulse Repetition Frequency 542
20.2.2.4 Tracking 543
20.2.2.5 High Data Rate Mode 543
20.2.3 Capabilities in Coastal Areas 543
20.2.4 Limitations 544
20.3 SAR Mode (Delay-Doppler) 544
20.3.1 Introduction 545
20.3.2 Key Innovations 545
20.3.3 Capabilities in Coastal Areas 547
20.3.4 Limitations 547
20.4 Wide Swath 548
20.4.1 Introduction 549
20.4.2 Key Innovations 549
20.4.2.1 Swath and Resolution 550
20.4.2.2 Mapping Ocean Surface Elevations 551
20.4.2.3 Elevation Accuracy 552
20.4.3 Capabilities in Coastal Areas 553
20.4.4 Limitations 555
20.5 Closing Comments 556
20.5.1 Commentary 556
20.5.1.1 Orbit Considerations 557
20.5.1.2 Averaging Considerations 557
20.5.1.3 Retrieval Algorithms 557
20.5.1.4 Crossover Considerations 558
20.5.2 Future Outlook 558
20.5.2.1 A Variation on the Wide Swath Theme 558
20.5.2.2 Variations on the Constellation Theme 559
20.5.3 Conclusions 559
References 560
Index 562