satellite altimetry over oceans and land surfaces
TRANSCRIPT
Satellite Altimetryover Oceans and
Land Surfaces
Detlef Stammer
Anny Cazenave
CRC PressTaylor &Francis GroupBoca Raton London NewYork
CRC Press is an imprint of the
Taylor & Francis Croup, an informa business
Contents
Preface xvii
Editors xxl
Contributors xxiii
Chapter 1 Satellite Radar Altimetry: Principle, Accuracy, and Precision 1
Philippe Escudier, Alexandre Couhert, Flavien Mercier, Alain Mallet,
Pierre Thibaut, Ngan Tran, Laiba Amarouche, Bruno Picard, Loren Carrere,
Gerald Dibarboure, Michael Ablain, Jacques Richard, Nathalie Steunou,
Pierre Dubois, Marie-Helene Rio, and Joel Dorandeu
1.1 Introduction 1
1.1.1 Satellite Altimetry Measurement Principle 1
1.1.2 Satellite Radar Altimetry Historical Perspective 4
1.1.2.1 Satellite Altimetry Missions 4
1.1.2.2 Geographical Perspective and International Cooperation....?1.1.2.3 Altimetry Products: History of Continuous Progress 10
1.1.3 Altimetry System Requirements 11
1.2 Radar Instrument 12
1.2.1 Radar Altimeter Instrument Principles 12
1.2.2 Observation Geometry 12
1.2.3 Radar Operation 13
1.2.4 Transmitted Waveform 13
1.2.5 Instrument Architecture 15
1.2.6 Instrument Example: Poseidon-3 of Jason-2 Mission 16
1.2.6.1 Poseidon-3 Architecture 16
1.2.6.2 Poseidon-3 Main Characteristics 17
1.2.7 Key Instrument Performance 17
1.2.8 Echo Formation 18
1.3 Echo characterization and processing 18
1.3.1 Speckle Noise 21
1.3.2 Analytical and Numerical Models 21
1.3.3 Estimation Strategies 22
1.3.4 New Altimeters 23
1.3.5 Non-Ocean Surfaces 23
1.4 Precise Orbit Determination 25
1.4.1 Orbit Determination Technique 26
1.4.1.1 Performance Requirements 26
1.4.1.2 Radial Error Properties 26
1.4.2 Orbit Determination Measurement Systems 27
1.4.3 Satellite Trajectory Modeling and Parameterization 29
1.4.4 Major Modeling Evolution since the Beginning of the 1990s 30
1.4.5 Long-Term Orbit Error and Stability Budget 32
1.4.6 Foreseen Modeling Improvement 34
1.5 Geophysical Corrections 37
1.5.1 Sea State Bias Correction 38
1.5.1.1 Origins of the Sea State Effects and Correction 38
1.5.1.2 Theoretical Solutions 38
1.5.1.3 Empirical Solutions 39
v\ Contents
1.5.2 Atmospheric Propagation Effect Corrections 40
1.5.2.1 Ionospheric Correction 40
1.5.2.2 Dry Tropospheric Correction 41
1.5.2.3 The Wet Tropospheric Correction 41
1.6 Altiraetry Product Auxiliary Information: Reference Surfaces, Tides,
and High-Frequency Signal 49
1.6.1 Reference Surfaces 50
1.6.2 Tides, High-Frequency Signals 51
1.6.2.1 The Tide Correction 51
1.6.2.2 The High-Frequency Correction 52
1.6.2.3 SI and S2 Atmospheric and Ocean Signals , 54
1.7 Altimetry Time and Space Sampling: Orbit Selection and Virtual
Constellation Approach 54
1.7.1 Sampling Properties of a Single Altimeter Orbit 54
1.7.2 Orbit Sub-Cycles and Sampling Properties 56
1.7.3 Altimeter Virtual Constellation and Phasing 57
1.8 Altimetry Error Budget 58
1.8.1 Error Budget for Mesoscale Oceanography 58
1.8.2 Error Budget for Mean Sea Level Trend Monitoring 60
1.8.3 Error Budget for Sub-Mesoscale 60
Glossary 62
References 62
Chapter 2 Wide-Swath Altimetry: A Review 71
Ernesto Rodriguez, Daniel Esteban Fernandez, Eva Peral, Curtis W. Chen,
Jan-Willem De Bleser, and Brent Williams
2.1 Introduction 71
2.2 Ocean and Hydrology Sampling Requirements 72
2.3 Approaches to Wide-Swath Altimetry 76
2.3.1 From Nadir Altimetry to Wide-Swath Altimetry: Three-
Dimensional Geolocation 76
2.3.2 Wide-Swath Altimetry Using Waveform Tracking 79
2.3.3 Wide-Swath Altimetry Using Radar Interferometry 79
2.4 The Interferometric Error Budget 82
2.4.1 Roll Errors 82
2.4.2 Phase Errors 83
2.4.3 Range Errors 85
2.4.4 Baseline Errors 85
2.4.5 Finite Azimuth Footprint Biases 86
2.4.6 Radial Velocity Errors 86
2.4.7 Calibration Methods 88
2.5 Wide-Swath Altimetry Phenomenology 91
2.5.1 Water Brightness 91
2.5.2 Wave Effects 91
2.5.2.1 The "Surfboard Effect" 92
2.5.2.2 Temporal Correlation Effects 93
2.5.2.3 Wave Bunching 95
2.5.2.4 The EM Bias 97
2.5.3 Layover and Vegetation Effects 98
2.6 Wide-Swath Altimetry Mission Design 102
Contents vii
2.7 Summary and Prospects 107
Acknowledgments 108
References 108
Chapter 3 In Situ Observations Needed to Complement, Validate, and InterpretSatellite Altimetry 113
Dean Roemmich, Philip Woodworth, Svetlana Jevrejeva, Sarah Purkey,Matthias Lankhorst, Uwe Send, and Nikolai Maximenko
3.1 Introduction 113
3.2 Sea Surface Heights Obtained from Tide Gauge/GNSS Networks 115
3.2.1 Sea Level Measurements before the Altimeter Era 115
3.2.2 Tide Gauge and Altimeter Data Complementarity 115
3.2.3 Tide Gauges Used for Altimeter Calibration 116
3.2.4 Tide Gauge and Altimeter Data in Combination in Studies of
Long-Term Sea Level Change 117
3.2.5 GNSS Equipment at Tide Gauges 118
3.2.6 New Developments in Tide Gauges and Data Availability 120
3.2.7 Tide Gauges and Altimetry in the Future 120
3.3 Upper-Ocean (0 to 2000 decibars) Steric Variability: The XBT and
Argo Networks 121
3.3.1 The Relationship of SSH Variability with Subsurface T and
S—Steric Height 121
3.3.2 A Brief History of Systematic Ocean Sampling by the XBT
and Argo Networks 122
3.3.3 Ocean Heat Content and Steric Sea Level 125
3.3.4 The Global Pattern of SSH and Upper-Ocean Steric Height 125
3.3.5 Geostrophic Ocean Circulation 126
3.3.6 Horizontal Scales of Variability in the Ocean: The Challengeof Resolution 127
3.4 Deep-Ocean (greater than 2000 m) Steric Variability:
Repeat Hydrography and Deep Argo 128
3.4.1 Ventilating the Deep Ocean: Deep Water Production and
the Global MOC 128
3.4.2 Monitoring Deep Steric Variability through Repeat Hydrography 129
3.4.3 The Deep Ocean Contribution to Steric Sea Level 129
3.4.4 Future of Deep Observing: Deep Argo 130
3.5 Geostrophic Transports and Bottom Pressure Observations 130
3.5.1 Complementarity among Altimetry, Water Column Density,and Bottom Pressure 130
3.5.2 Volume Transports from End Points, and Accuracy Requirements.... 130
3.5.3 Upper-Layer Transports 132
3.5.4 Complementarity of Altimetry and Seafloor Pressure in
Accuracy and Timescales 134
3.5.5 Constraining Transports in Two-Mode Systems with Altimetryand Bottom Pressure 135
3.6 Dynamic Topography and Surface Velocity 136
3.6.1 Eulerian Velocity Measurements 136
3.6.2 Lagrangian Velocity Measurements 136
3.6.3 Geostrophic Currents and Mean Dynamic Topography 137
3.6.4 Ageostrophic Motions 139
viii Contents
3.7 The Technology Revolution and the Future of Ocean Observations 140
3.8 Outlook 140
Acknowledgments 140
References 141
Chapter 4 Auxiliary Space-Based Systems for Interpreting Satellite Altimetry:Satellite Gravity 149
Don Chambers, Ole B. Andersen, Srinivas Bettadpur, Marie-Helene Rio,
Reiner Rummel, and David Wiese
4.1 Introduction 149
4.2 Measurements: Mean Geoid and Sea Surface 150
4.2.1 Parameterizing Gravity and the Geoid 151
4.2.2 GRACE and GOCE 154
4.2.3 Surface Gravity Data and Combination Geoids 158
4.2.4 Mean Sea Surface Models 159
4.3 Measurements: Time-Variable Gravity 161
4.4 Applications: Dynamic Ocean Topography 164
4.4.1 Importance of Consistency between Geoid and MSS 165
4.4.2 Improvements in MDT with GRACE and GOCE Geoids 168
4.4.3 Toward a Higher Spatial Resolution MDT 172
4.5 Applications: Global and Regional Ocean Mass Variations 173
4.6 Conclusions and Future Prospects 178
References 180
Chapter 5 A 25-Year Satellite Altimetry-Based Global Mean Sea Level Record:
Closure of the Sea Level Budget and Missing Components 187
R. Steven Nerem, Michael Ablain, Anny Cazenave, John Church,
and Eric Leuliette
5.1 Introduction 187
5.2 The Altimeter Mean Sea Level Record 189
5.2.1 Computing Global and Regional Mean Sea Level Time Series 189
5.2.2 Altimeter Missions 189
5.2.3 Altimeter Corrections 189
5.2.4 Intermission Biases 190
5.2.5 Averaging Process 190
5.2.6 Validation ofthe GMSL Record with Tide Gauge Measurements 191
5.2.7 Mean Sea Level Variation and Uncertainties 192
5.2.7.1 Global Scale Uncertainty 192
5.2.7.2 Regional Scales 194
5.3 Interpreting the Altimeter GMSL Record 194
5.3.1 Steric Sea Level Contribution 195
5.3.2 The Cryosphere Contributions to GMSL 198
5.3.3 The Land Water Storage Contributions to GMSL 199
5.3.3.1 Interannual Variations 200
5.3.3.2 Long-Term Variations 201
5.4 Closing the Sea Level Budget and Uncertainties 201
5.4.1 Glacial Isostatic Adjustment 202
5.4.2 Ocean Mass/Barystatic Sea Level from GRACE 202
5.4.3 Closure and Missing Components 203
Contents lx
5.5 How Altimetry Informs Us About the Future 204
References 204
Chapter 6 Monitoring and Interpreting Mid-Latitude Oceans by Satellite Altimetry 211
Kathryn A. Kelly, Joshua K. Willis, Gilles Reverdin, Shenfu Dong,and LuAnne Thompson6.1 Introduction: Role of Mid-Latitude Oceans 211
6.2 Western Boundary Currents 212
6.3 Meridional Circulation and Interbasin Exchanges 217
6.4 Climate Change 221
6.5 Summary and Future Research 226
Acknowledgments 226
References 226
Chapter 7 Monitoring and Interpreting the Tropical Oceans by Satellite Altimetry 231
Tong Lee, J. Thomas Farrar, Sabine Arnault, Benoit Meyssignac,
Weiqing Han, and Theodore Durland
7.1 Introduction 231
7.2 Tropical Atlantic Ocean 232
7.2.1 Intraseasonal and Eddy Activities 232
7.2.1.1 Eddy Structures 232
7.2.1.2 Tropical Instability Waves 233
7.2.2 The Seasonal Cycle 233
7.2.3 Equatorial Waves 234
7.2.4 Interannual Variability 235
7.3 Tropical Indo-Pacific Ocean 236
7.3.1 Tropical Pacific 236
7.3.1.1 Intraseasonal Variability 236
7.3.1.2 Seasonal Variability 239
7.3.1.3 Interannual and Decadal Variability 244
7.3.2 Tropical Indian Ocean 249
7.3.2.1 Intraseasonal Variability 249
7.3.2.2 Seasonal Cycle 252
7.3.2.3 Interannual Variability 253
7.3.2.4 Decadal and Multidecadal Changes 255
7.3.3 Indo-Pacific Linkage and Indonesian Throughflow 256
7.4 Summary 257
Acknowledgments 258
References 258
Chapter 8 The High Latitude Seas and Arctic Ocean 271
Johnny A. Johannessen and Ole B. Andersen
8.1 Introduction 271
8.1.1 Satellite Altimetry in the High Latitude and Arctic Ocean 273
8.2 Mapping the Sea Ice Thickness in the Arctic Ocean 275
8.3 Sea Level Change 276
8.3.1 The Seasonal Cycle 278
8.3.2 Secular and Long-Term Sea Level Changes 279
X Contents
8.3.3 Arctic Sea Level Budget 282
8.3.4 The Polar Gap and Accuracy Estimates 283
8.4 Mean Dynamic Topography 284
8.5 Ocean Circulation and Volume Transport 285
8.5.1 Surface Circulation 285
8.5.2 Volume Transport 289
8.6 Summary and Outlook 290
Acknowledgment 291
References 291
Chapter 9 The Southern Ocean 297
Sarah T. Gille and Michael P. Meredith
9.1 Introduction 297
9.2 Characterizing Spatial Variability of the Antarctic CircumpolarCurrent from Altimetry 297
9.3 Mapping the Time-Varying, Three-Dimensional Structure of
the Southern Ocean 299
9.4 ACC Transport From Altimetry 301
9.5 Eddy Variability 306
9.6 Summary and Conclusions 309
Acknowledgments 310
References 310
Chapter 10 Ocean Eddies and Mesoscale Variability 315
Rosemary Morrow, Lee-Lueng Fu, J. Thomas Farrar, Hyodae Seo,
and Pierre-Yves he Traon
10.1 Introduction 315
10.2 Improvements in Along-Track Data and Mapping Capabilities 316
10.2.1 Reprocessing of Along-Track Data 317
10.2.2 Multi-Mission Mapping 317
10.3 Observed Mesoscale Eddies and Jets 319
10.4 Spectral Analyses of Along-Track SSH 321
10.5 Resolving Higher-Order Dynamical Processes 325
10.5.1 Toward Two-Dimensional Spectral Energy Fluxes 325
10.5.2 Lagrangian Fine-Scale Ocean Dynamics from Altimetry 325
10.6 Understanding Three-Dimensional Vertical Structure of Eddy and
Sub-Mesoscale Processes 326
10.7 Understanding Coupled Mesoscale Processes 329
10.8 Effects of Internal Waves at Smaller Spatial Scales 332
10.9 Summary and Perspectives 333
Acknowledgments 335
References 335
Chapter 11 Satellite Altimetry in Coastal Regions 343
Paolo Cipollini, Jerome Benveniste, Florence Birol, M. Joana Fernandes,
Estelle Obligis, Marcello Passaro, P. Ted Strub, Guillaume Valladeau,
Stefano Vignudelli, and John Wilkin
Glossary 343
11.1 Introduction and Rationale 344
Contents xi
11.2 Dealing with Coastal Waveforms 346
11.2.1 Pulse-Limited Waveforms 346
11.2.2 SAR Waveforms 349
11.3 Improvements in Range and Geophysical Corrections 350
11.3.1 Dry Troposphere 350
11.3.2 Wet Troposphere 351
11.3.3 Recent Improvements in Coastal Tides and Dynamic
Atmospheric Correction 356
11.4 Data Available for Coastal Altimetry 356
11.4.1 PEACHI Expertise Prototype 356
11.4.1.1 SARAL/AltiKa 358
11.4.1.2 Implementation on Jason-2 and Jason-3 359
11.4.1.3 Data Availability and Delivery Mode 359
11.4.2 ALES '. 359
11.4.2.1 ALES Data Set: Availability and Reliability 359
11.4.2.2 ALES Data Set Improves Coastal Sea Level Research.... 360
11.4.2.3 Examples of Usage of the ALES Data Set 362
11.4.3 X-TRACK Regional Altimetry Products 362
11.5 Applications Using Observations Alone 364
11.6 Integration of Coastal Altimetry in Coastal Observing Systems 370
11.7 Conclusions 372
Acknowledgment 373
References 373
Chapter 12 Monitoring Waves and Surface Winds by Satellite Altimetry: Applications 381
Saleh Abdalla and Peter A. E. M. Janssen
12.1 Introduction 381
12.2 The Altimeter and Its Ocean Measurements 383
12.3 Altimeter Surface Wind Speed 386
12.3.1 Principle of Wind Speed Measurement 386
12.3.2 Quality of Altimeter Wind Speed Observations 388
12.3.3 Benefits of Altimeter Wind Speed Observations 392
12.3.4 Altimeter Wind Speed Data and Problems 394
12.3.4.1 Effect of Slicks 397
12.3.4.2 Neutral versus 10-m Winds 397
12.3.4.3 Sea State Effects 398
12.3.5 Backscatter versus Mean Square Slope 399
12.3.6 Extreme Winds 400
12.4 Significant Wave Height 402
12.4.1 Principle of SWH Measurement 402
12.4.2 Quality of Altimeter SWH Data 402
12.5 Applications 406
12.5.1 Data Assimilation 406
12.5.2 Estimation of Effective Model Resolution 413
12.5.3 Sea State Climatology 414
12.6 New Developments 417
12.6.1 SAR (Delay-Doppler) Altimetry 417
12.6.2 CFOSAT 418
12.7 Concluding Remarks 420
References 420
xii Contents
Chapter 13 Tides and Satellite Altimetry 427
Richard D. Ray and Gary D. Egbert13.1 Introduction 427
13.2 Tidal Aliasing 428
13.3 Barotropic Tidal Models for and from Satellite Altimetry 431
13.4 Barotropic Tidal Energetics 436
13.5 Baroclinic Tides 444
13.5.1 Stationary Baroclinic Tides 445
13.5.2 Nonstationary Baroclinic Tides 448
13.6 Outstanding Issues 453
Acknowledgments 454
References 454
Chapter 14 Hydrological Applications of Satellite Altimetry: Rivers, Lakes, Man-Made
Reservoirs, Inundated Areas 459
Jean-Francois Cretaux, Karina Nielsen, Frederic Frappart, Fabrice Papa,
Stephane Calmant, and Jerome Benveniste
14.1 Introduction 459
14.1.1 Past, Present, and Future of Satellite Altimetry 460
14.1.2 Short History of Past Applications of Satellite Altimetry on
Surface Water 462
14.1.3 Objectives of This Chapter 463
14.2 Satellite Altimetry: Measurement and Interpretation 463
14.2.1 General Principle of Satellite Altimetry 463
14.2.2 Jason-2 DIODE/DEM Tracker 465
14.2.3 Review of the Different Modes (LRM, SAR, and SARIn) 465
14.2.4 Review of the Geophysical Corrections 466
14.2.4.1 Dry Tropospheric Correction 466
14.2.4.2 Wet Tropospheric Correction 466
14.2.4.3 Ionospheric Correction 466
14.2.4.4 Sea State Bias Correction 467
14.2.4.5 Tidal Corrections 467
14.2.5 Review of the Biases and Their Determination 467
14.3 Satellite Altimetry for Hydrology: Some Basics 468
14.3.1 Review of the Retracking and Height Retrieval 468
14.3.1.1 Ocean and Ice-2 Retrackers 470
14.3.1.2 OCOG Retracker 471
14.3.1.3 Sea Ice Retracker 471
14.3.1.4 Threshold Retracker 471
14.3.2 Hooking Effect 472
14.3.3 Geoid Gradient Correction over Lakes 474
14.3.4 Selection and Editing of Measurements for Hydrology 475
14.3.5 Cross-Track Correction for SARIn and Snagging 480
14.4 Examples of Application 483
14.4.1 Use of Altimetry over Lakes and Reservoirs 483
14.4.1.1 Regional Survey of Lakes (Tibetan Plateau Lakes) 483
14.4.1.2 Case Study on Lakes Using SAR/SARIn 485
14.4.2 Use of Satellite Altimetry over Rivers 489
14.4.3 Use of Satellite Altimetry over Floodplains 491
Contents x"'
14.4 Conclusions and Perspectives 495
References 498
Chapter 15 Applications of Satellite Altimetry to Study the Antarctic Ice Sheet 505
Frederique Remy, Anthony Memin, and Isabella Velicogna15.1 Introduction 505
15.2 The Antarctica Ice Sheet 506
15.2.1 General Characteristics 506
15.2.2 How to Observe the Evolution of the Ice Sheet 508
15.3 Polar Altimetry 508
15.3.1 Some Specifics of Radar Altimetry on Ice Sheets 508
15.3.2 Characteristics of Laser Altimetry on Ice Sheets 510
15.3.3 Methodology for Constructing Height Time Series 510
15.4 Contribution of Altimetry to Studying Antarctic Climate 511
15.5 Main Surface Characteristics of the Antarctic Ice Sheet 511
15.5.1 Surface Topography 512
15.5.2 Constraints for Numerical Models 513
15.6 Temporal Variations 514
15.6.1 Different Times and Signals 514
15.6.2 Lake Drainage 515
15.6.3 Firn Compaction 515
15.6.4 Present-Day Mass Balance 516
15.6.5 Acceleration of Outlet Glaciers 517
15.7 Summary and Perspective 518
References 519
Chapter 16 Advances in Imaging Small-Scale Seafloor and Sub-Seafloor Tectonic
Fabric Using Satellite Altimetry 523
R. Dietmar Miiller, Kara J. Matthews, and David T. Sandwell
16.1 Introduction 523
16.2 Satellite-Derived Gravity for Tectonic Mapping 523
16.2.1 Brief History 523
16.2.2 Methodology and Limitations 524
16.2.3 Improved Radar Technology—Current and Future 526
16.3 Oceanic Microplates 527
16.3.1 Models for Microplate Formation 527
16.3.2 Associated Seafloor Structures 530
16.3.3 Recent Advances in Mapping the Structure and History of
Microplates Using Satellite Altimetry 530
16.3.3.1 Indian Ocean 531
16.3.3.2 Pacific Ocean 532
16.4 Mapping Major Tectonic Events in the Ocean Basins 534
16.4.1 The Enigmatic Mid-Cretaceous Tectonic Event 534
16.4.2 Insights from Combining Satellite Altimetry with Geologicaland Geophysical Ship Data 537
16.4.3 What Caused the 100 Ma Event? 539
16.5 Mapping Sub-Seafloor Tectonic Fabric 539
16.5.1 North Falkland Basin 540
16.5.2 Lord Howe Rise 542
xiv Contents
16.6 Conclusions and Future Outlook 542
Acknowledgments 542
References 544
Chapter 17 Ocean Modeling and Data Assimilation in the Context of Satellite Altimetry 547
Detlef Stammer and Stephen M. Griffies17.1 Introduction 547
17.1.1 Observational Oceanography and Ocean Circulation Modeling 547
17.1.2 The Need for Ocean Data Assimilation 548
17.1.3 Aims for This Chapter 548
17.2 Ocean General Circulation Models 548
17.2.1 The Hydrostatic Primitive Equations 548
17.2.2 Flux-Form Ocean Equations 550
17.2.3 Basics of Finite Volume Discrete Ocean Equations 551
17.2.4 Oceanic Boussinesq Approximation 551
17.2.5 Ocean Responses to Virtual Salt Fluxes versus Real Water Fluxes....552
17.2.6 Impacts from Changes to the Gravitational Geopotential 553
17.2.7 Fast and Slow Dynamics 553
17.3 Sea Level Tendencies and Spatial Patterns 555
17.3.1 Sea Level Tendencies and Mass Continuity 556
17.3.2 Non-Boussinesq Steric Effect and the Boussinesq Sea Level 556
17.3.3 Evolution of Global Mean Sea Level 557
17.3.3.1 Mass Conserving Non-Boussinesq Fluids 557
17.3.3.2 Volume-Conserving Boussinesq Fluids 558
17.3.4 Sea Level Tendencies and the Hydrostatic Balance 558
17.3.5 Sea Level Tendencies due to Mass Changes 559
17.3.6 Sea Level Tendencies due to Local Steric Changes 560
17.3.7 Sea Level Changes due to Applied Surface Loading 560
17.3.8 Sea Level Gradients and Ocean Circulation 561
17.3.8.1 Surface Ocean 561
17.3.8.2 Full Ocean Column 561
17.3.8.3 Barotropic Geostrophic Balance and Transport
through a Section 562
17.4 Ocean Data Assimilation 562
17.4.1 Elements of Ocean Data Assimilation 563
17.4.2 Some Details for Filtering Methods 565
17.4.3 Smoother Methods 566
17.5 Applications with Respect to Altimetry 567
17.5.1 Process Modeling 567
17.5.2 Assimilation of Sea Level into Models 571
17.6 Summary and Concluding Remarks 574
Acknowledgments 574
References 574
Chapter 18 Use of Satellite Altimetry for Operational Oceanography 581
Pierre-Yves Le Traon, Gerald Dibarboure, Gregg Jacobs, Matt Martin,
Elisabeth Remy, and Andreas Schiller
18.1 Introduction 581
Contents xv
18.2 Operational Oceanography 582
18.2.1 History of Development 582
18.2.2 Operational Oceanography Infrastructure 582
18.2.3 Applications and Users 583
18.3 The Unique Role of Satellite Altimetry for Operational Oceanography 584
18.3.1 The Close Relationships between Operational Oceanographyand Satellite Altimetry 584
18.3.2 Synergies with Other Satellite and In Situ Observations 584
18.3.3 General Requirements/Constellation 585
18.4 Use and Impact of Satellite Altimetry for Operational Oceanography 586
18.4.1 Evolution of the Altimeter Constellation over the Last 25 Years 586
18.4.2 Multiple Altimeter Data Processing for Operational
Oceanography 587
18.4.2.1 Level 2 Data Assembly and Homogenization 589
18.4.2.2 Intercalibration, Orbit, and Large-ScaleError Correction 589
18.4.2.3 Calculation of Sea Level Anomalies 590
18.4.2.4 Strengthening the Links with DataAssimilation Systems.... 591
18.4.2.5 Mapping SLA on Regular Space and Time Grids 591
18.4.2.6 Geoid and Mean Dynamic Topography 592
18.4.3 Assimilation in Ocean Forecasting Models 593
18.4.4 Impact of Multiple Altimeter Data Assimilation in Ocean
Forecasting Models 594
18.5 Future prospects 598
18.5.1 Evolution of Operational Oceanography and New Challenges 598
18.5.2 Evolution of Altimetry Technology and Impact on
Operational Oceanography 602
18.5.2.1 Improving Coverage and Robustness 602
18.5.2.2 Improving Precision and Accuracy 603
18.6 Conclusion 604
References 604
Index 609