Gravity, Geoid and Earth Observation (eBook)

Preface 6
Contents 9
Contributors 18
Part I Gravimetry (Terrestrial, Shipborne, Airborne) and Gravity Networks 34
Chapter 
35 
1.1 Introduction 35
1.2 Setup of the Airborne Experiment 36
1.2.1 Instrumentation 36
1.2.2 Test Area and Trajectory 36
1.2.3 Precise Point Positioning 37
1.3 Observational Model 37
1.4 Data Processing 38
1.5 Preliminary Results 38
1.6 Summary and Outlook 40
References 41
Chapter 
42 
2.1 Introduction 42
2.2 Dislocation Theory Applicable in Satellite Data 43
2.3 Co-seismic Gravity Changes on the Deformed Earth Surface 44
2.4 Co-seismic Gravity Changes at Space-Fixed Point 45
2.5 Co-seismic Gravity Changes by Damping High-Frequency Part 46
2.6 Are Co-seismic Gravity Changes Detectable for a M8.4 Earthquake? 46
2.7 Summary 47
References 47
Chapter 
49 
3.1 Anomalous Gravity Gravity Anomaly and Disturbance 49
3.2 Topographically Corrected Anomalous Gravity 50
3.3 Bouguer Anomaly Ambiguous Definitions 51
3.4 Gravity Data Geophysical Versus Geodetic Applications 52
3.5 Conclusion 53
References 53
Chapter 
55 
4.1 Gravity Data Inversion/Interpretation 55
4.2 Regions of Negative Heights 56
4.3 RQE Approach 57
4.4 Reverting from RQE to RE Approach 58
4.5 Case Study 58

59 
References 59
Chapter 
61 
5.1 Introduction 61
5.2 Protocol 63
5.3 Data Processing 63
5.4 Adjustment of the Data 63
5.5 Conclusions 65
References 65
Chapter 
66 
6.1 Introduction 66
6.2 The Aerogravity System 67
6.3 System Installation 68
6.4 Aerogravity Survey of the German Bight 68
6.5 Data Processing 68
6.6 Data Accuracy 71
6.7 Map of the Free-Air Gravity Anomalies 71
6.8 Summary and Further Work 73
References 75
Chapter 7 Results of the Seventh International Comparison of Absolute Gravimeters ICAG-20050at the Bureau International des Poids et Mesures, Sevres 76
7.1 Introduction 76
7.2 Absolute Measurements 77
7.3 Results of ICAG-2005 77
7.4 Conclusions 81
References 82
Chapter 
83 
8.1 Introduction 83
8.2 Mathematical Definitions 83
8.3.1 The World Function 83
8.2.2 
84 
8.3 Model Assumptions 84
8.4 Measurement Formulation for the Relative Distance 84
8.4.1 
85 
8.5 Gravimetric Interpretation 85
8.6 Conclusions 86
References 86
Chapter 
87 
9.1 Introduction 87
9.2 Least Squares Adjustment 88
9.3 Robust Estimates 88
9.4 Robust and Efficient Estimation 89
9.4.1 
89 
9.4.2 
89 
9.5 Results and Comparison 90
9.6 Conclusions 92
References 93
Chapter 
94 
10.1 Introduction 94
10.2 Processing of GPS Derived SSH Data 96
10.2.1 
96 
10.2.2 
96 
10.2.3 
97 
10.2.4 
97 
10.3 Comparisons with JASON-1 and ICESat Altimetry Data 97
10.4 Comparisons with Global and Local Geoid Models 99
10.5 Conclusions 99
References 100
Chapter 
101 
11.1 Introduction 101
11.2 Setup 101
11.3 Experimental Results 103
11.3.1 
103 
11.3.2 
103 
11.3.3 
104 
11.4 Specifications and Terminology 105
11.5 Conclusions 106
References 107
Chapter 12 Absolute Gravimetry at BIPM, Sevres (France), at the Time of Dr. Akihiko Sakuma 108
12.1 Introduction 108
12.2 Absolute Gravity Measurementsat BIPM First Stage: 1888-1960 109
12.2.1 
109 
12.2.2 
110 
12.2.2.1 
110 
12.2.2.2 
110 
12.3 Absolute Gravity at BIPM:Dr. Sakumas Work 1960-1996 111
12.3.1 
111 
12.3.1.1 
111 
12.3.1.2 
111 
12.3.2 
113 
12.3.2.1 
113 
12.3.2.2 
114 
12.4 Absolute Gravity at BIPM: Present and Future 115
References 116
Chapter 
117 
13.1 Introduction 117
13.2 Methodology 118
13.2.1 
118 
13.2.2 
118 
13.2.3 
119 
13.3 Simulation Study 120
13.3.1 
120 
13.3.2 
120 
13.4 Test Flight 120
13.5 Summary and Outlook 122
References 124
Chapter 
125 
14.1 Introduction 125
14.2 The IMGC-02 Transportable Absolute Gravimeter 125
14.3 Logistics and Environmental Conditions 126
14.4 Results 128
14.5 Conclusion 129
References 129
Chapter 
130 
15.1 Introduction 130
15.2 Site Description 130
15.3 Gravimeter Installation 131
15.3.1 
132 
15.4 GPS and SLR Analysis 133
15.5 Discussion 133
15.6 Conclusions 135
References 136
Chapter 
137 
16.1 Introduction 137
16.2 Experimental Set Up 138
16.3 Vibration Correction 139
16.3.1 
139 
16.3.2 
140 
16.4 Measurements Without Isolation 140
16.4.1 
140 
16.4.2 
140 
16.4.3 
141 
16.5 Conclusion 143
References 143
Chapter 
144 
17.1 Introduction 144
17.2 Basic Theory 144
17.3 Data Comparisons 146
17.4 Conclusion 147
References 148
Part II Space-Borne Gravimetry: Present and Future 149
Chapter 
150 
18.1 Introduction 150
18.2 Mission Scenarios 151
18.3 Retrieval Experiments 152
18.3.1 
153 
18.3.2 
154 
18.4 Conclusions and Outlook 156
References 156
Chapter 
158 
19.1 Introduction 158
19.2 Data Processing 159
19.2.1 
160 
19.2.2 
161 
19.2.3 
161 
19.2.4 
162 
19.3 Results 163
19.3.1 
163 
19.3.2 
163 
19.4 Conclusions 165
References 165
Chapter 
166 
20.1 Principles 166
20.2 The Inverse Calibration Matrix 167
20.3 Functional Models 167
20.3.1 
168 
20.3.2 
168 
20.3.3 
169 
20.4 Calibration Results 169
20.4.1 
169 
20.4.2 
170 
20.5 Conclusions 172
References 172
Chapter 
174 
21.1 Introduction 174
21.2 Mathematical Formulation 174
21.3 Test Data Sets 176
21.4 Gravity Field Recovery 177
21.4.1 
177 
21.4.2 
177 
21.5 Conclusion 179
References 179
Chapter 
181 
22.1 Introduction 181
22.2 Spatio-Temporal Sampling and the Heisenberg Sampling Rule 182
22.2.1 
182 
22.2.2 
183 
22.3 Simulations 183
22.4 Results 184
22.5 Discussion 187
References 187
Chapter 
189 
23.1 Introduction 189
23.2 Closed Loop Simulation 190
23.3 Observation Noise 191
23.4 Model Errors 192
23.5 Conclusions 193
References 194
Chapter 24 GRACE Gravity Field Determination Using the Celestial Mechanics Approach - First Results 195
24.1 Introduction 195
24.2 Celestial Mechanics Approach 196
24.2.1 
196 
24.2.2 
196 
24.2.3 
197 
24.2.4 
197 
24.3 Error-Free Simulation 197
24.4 Processing Real Data 198
24.4.1 
198 
24.4.2 
199 
24.4.2.1 
199 
24.4.2.2 
200 
24.4.2.3 
200 
24.5 Validation with External Data 200
24.6 Conclusions 201
References 201
Chapter 
203 
25.1 Introduction 203
25.2 VCE as Part of an Iterative Solver 205
25.3 Effect of Inaccuracies in the Weights 205
25.3.1 
205 
25.3.2 
207 
25.3.3 
207 
25.4 Numerical Simulations 207
25.4.1 
208 
25.4.2 
209 
25.4.3 
209 
25.4.4 
210 
25.5 Summary and Outlook 210
References 211
Chapter 
212 
26.1 Introduction 212
26.2 Study on the Structure of the Error Covariance Matrix 213
26.2.1 
213 
26.2.2 
214 
26.3 Study of Optimal Model Combinations 215
26.3.1 
215 
26.3.2 
216 
26.3.3 
217 
26.3.4 
218 
26.3.5 
218 
26.4 Conclusions 218
References 219
Part III Earth Observation by Satellite Altimetry and InSAR 220
Chapter 
221 
27.1 Introduction 221
27.2 Data 221
27.3 Sigma0 Variation from Envisat Ku Band 221
27.4 Creation of Empirical Sigma0 Models 223
27.5 The Simpson Desert 24-28S, 135-139E 224
27.6 The Congo 4S-4N, 16-26E 224
27.7 Understanding Sigma0 224
27.8 Modelling Moisture Response for Western Australia (22-32S116-128E) 226
27.9 Discussion 226
References 228
Chapter 
229 
28.1 Introduction 229
28.2 Waveform Shape Analysis 229
28.3 Retracking 233
28.4 Regional Study 234
28.5 Burst Echoes 234
28.6 Discussion 236
References 236
Chapter 
237 
29.1 Introduction 237
29.2 Global Analysis 237
29.3 Example Systems and Analysis 239
29.3.1 
239 
29.3.2 
240 
29.4 Near-Real-Time Measurements 240
29.4.1 
241 
29.4.2 
242 
29.5 Burst Echoes 243
29.6 Discussion 244
References 245
Chapter 
246 
30.1 Introduction 246
30.2 Topography 246
30.3 Global Comparison 247
30.4 Data Fusion 250
30.5 ACE2 Characteristics 250
30.5 ACE2 Characteristics 251
30.6 Discussion 251
References 251
Chapter 
253 
31.1 Introduction 253
31.2 GPS Observations of Ocean Dynamic Topography 254
31.3 GPS Antenna Height Determination 254
31.4 Determining the Mean Dynamic Topography 255
31.5 First Results 257
31.6 Outlook 258
References 258
Chapter 
260 
32.1 Introduction 260
32.2 Generation of a 
261 
32.2.1 
262 
32.2.2 
262 
32.3 Filtering 262
32.4 Numerical Results 263
32.5 Conclusions 264
References 264
Chapter 
266 
33.1 Introduction 266
33.2 Data and Methods 266
33.3 Results 267
33.3.1 
267 
33.3.2 
267 
33.3.3 
267 
33.3.4 
270 
33.4 Conclusions 270
References 273
Chapter 
275 
34.1 Introduction 275
34.2 GRACE-Only Gravity Field Models 276
34.3 Satellite Altimetry Profiling the Sea Surface 277
34.4 The Profile Approach 277
34.5 Results 278
34.6 Validation 279
34.7 Conclusion 280
References 280
Part IV Geoid Modeling and Vertical Datums 282
Chapter 
283 
35.1 Introduction 283
35.2 Gravimetric Reduction Method 284
35.2.1 
284 
35.2.2 
286 
35.3 Comparison and Results 289
35.3.1 
289 
35.3.2 
289 
35.4 Conclusions 291
References 291
Chapter 
292 
36.1 Introduction 292
36.2 Used Data 292
36.3 HVRS71 and TRIESTE Height Datum 293
36.4 HRG2000 National Geoid Model 293
36.5 Global Geopotential Models 294
36.6 Results 295
36.7 Conclusions 296
References 297
Chapter 
298 
37.1 Introduction 298
37.2 Study Area 299
37.3 SCM vs. SRTM Data Comparisons 299
37.4 ICESat vs. SRTM Data Comparisons 300
37.5 Conclusions 302
References 303
Chapter 
304 
38.1 Introduction 304
38.2 Methodology 305
38.3 Description of Data 306
38.4 Analysis of Results 307
38.4.1 
307 
38.4.2 
307 
38.5 Conclusions and Recommendations 308
References 310
Chapter 
312 
39.1 Introduction 312
39.2 GPS/Levelling Data 312
39.3 Comparisons 313
39.3.1 
313 
References 315
Chapter 
317 
40.1 Introduction 317
40.2 The Integrated Approach 317
40.3 The Model Function Approach 318
40.4 A Hybrid Interpolation Approach 319
40.5 System Theory in Gravity Field Modeling 320
40.6 Conclusions 322
References 322
Chapter 
323 
41.1 Introduction 323
41.2 EUVNDA: Densification of EUVN 324
41.3 Analysis of the GPS/Leveling Data 325
41.4 Towards the Combined European Height Reference Surface 326
41.5 Summary and Outlook 327
References 328
Chapter 
329 
42.1 Introduction 329
42.2 A General View of Vertical Datums Connection 330
42.3 A Test Approach for SST Determination at the BVD 330
42.4 Mean Lagoon Level (MLL) 331
42.5 Data Analysis 332
42.5.1 
332 
42.5.2 
334 
42.6 Final Remarks 334
References 335
Chapter 
336 
43.1 Introduction 336
43.2 Normal Heights and Height Anomalies 337
43.3 Interpolation Techniques 337
43.3.1 
338 
43.3.2 
338 
43.3.3 
338 
43.4.4 
338 
43.4 Analysis and Conclusions 339
References 339
Chapter 
340 
44.1 Introduction 340
44.2 Mathematical Formulations 340
44.3 Practical Solutions 342
44.4 Conclusion 344
References 344

346 
Chapter 
347 
45.1 Introduction 347
45.2 The Used Data 348
45.2.1 
348 
45.2.2 
348 
45.2.3 
349 
45.2.4 
349 
45.3 Overview on the Gravimetric Geoid Models of Algeria 350
45.4 High-Resolution Geoid Computation 350
45.5 Comparison of All Gravimetric Geoid Models with GPS/Levelling Data 351
45.6 Conclusion 353
References 353
Chapter 
354 
46.1 Introduction 354
46.2 Numerical Realization 355
46.2.1 
355 
46.2.2 
355 
46.2.3 
357 
46.3 Summary and Conclusions 358
References 358
Chapter 47 Effect of the Long-Wavelength Topographical Correction on the Low-Degree Earth's Gravity Field 360
47.1 Long-Wavelength Gravitational Field Generated by the Topography 360
47.2 Numerical Experiment 361
47.3 Conclusions 361
Appendix 364
References 365
Chapter 
366 
48.1 Introduction 366
48.2 Integration Methods 366
48.2.1 
367 
48.2.2 
367 
48.2.3 
367 
48.2.4 
368 
48.2.5 
368 
48.3 Numerical Experiment 368
48.4 Conclusions 371
References 372
Chapter 
374 
49.1 Introduction 374
49.2 Computation Strategy and Results 375
49.3 Geoid Model Validation 377
49.4 Combined Solution 378
49.5 Conclusions-Future Plans 379
References 379
Chapter 
381 
50.1 Introduction 381
50.2 Topographic-Isostatic Effect 382
50.3 Downward Continuation 383
50.4 Results 383
50.5 Conclusions 385
References 385
Appendix 386
Chapter 
387 
51.1 1 Introduction 387
51.2 Study Area 387
51.3 Data Description 388
51.3.1 
388 
51.3.2 
388 
51.4 Models Evaluation 389
51.5 Conclusions 390
References 392
Chapter 
393 
52.1 Introduction 393
52.2 Problem of Negative Terrain Correction in Spherical Approach 394
52.3 Convergence of the Terrain Correction with Growing Distance from the Computation Point 396
52.4 Conclusions 398
References 399
Chapter 
400 
53.1 Introduction 400
53.2 Numerical Experiment 400
53.3 Conclusions 408
References 408
Chapter 
409 
54.1 Introduction 409
54.2 Geoid Determination Based on the Least-Squares Modification of Stokes Formula 410
54.2.1 
410 
54.2.2 
411 
54.2.3 
412 
54.3 Geoid Computation 412
54.4 Evaluation of the Gravimetric Geoid Model 414
54.5 Concluding Remarks 415
References 415
Chapter 
416 
55.1 Introduction 416
55.2 Getting the VDCs 417
55.2.1 
417 
55.2.2 
417 
55.2.3 
418 
55.2.4 
418 
55.3 Test Results 419
55.4 Conclusions 419
References 420
Chapter 
422 
56.1 Introduction 422
56.2 Formulation of the Mixed GBVP 422
56.3 Solution of the Mixed GBVP by FEM 423
56.4 Numerical Experiments by FEM 424
56.5 Solution of the Mixed GBVP by FVM 424
56.5.1 
426 
56.6 Numerical Experiments by FVM 426
56.7 Conclusions 427
References 427
Chapter 
428 
57.1 Introduction 428
57.2 Preparation and Validation of Gravity Data 429
57.2.1 
429 
57.2.2 
430 
57.2.3 
430 
57.3 Computation of Quasi-Geoid 431
57.3.1 
431 
57.3.2 
431 
57.3.3 
432 
57.3.4 
433 
57.4 Analysing the Difference Between the Geoid and the Mean Sea Level Measured at Tide Gauges 435
57.4.1 
435 
57.4.2 
435 
57.4.3 
435 
57.5 Conclusion 436
References 436
Chapter 
437 
58.1 Introduction 437
58.2 Algorithm 438
58.3 Assessment 439
58.3.1 
440 
58.3.2 
441 
58.3.3 
441 
58.4 Conclusions 442
References 443
Chapter 
444 
59.1 Motivation 444
59.2 Survey Description 445
59.3 Data Processing and Validation 445
59.4 Results and Discussion 447
59.5 Conclusions 449
References 449
Chapter 
450 
60.1 The Problem and Proposed Solution 450
60.2 Results of Numerical Experiments 452
60.3 Conclusions and Future Works 454
References 455
Part VI Global Gravity Field Modeling and EGMO8 456
Chapter 
457 
61.1 Introduction 457
61.2 Global Geopotential Model 458
61.3 Data Used 458
61.3.1 
458 
61.3.2 
459 
61.3.3 
459 
61.4 Evaluation of the EGM2008 460
61.4.1 
460 
61.4.2 
461 
61.4.3 
461 
61.5 Comparisons Up to Degree 2,190 and Order 2,159 461
61.6 Conclusion 463
References 463
Chapter 
465 
62.1 Introduction 465
62.2 Direct BEM for the Linearized FGBVP 465
62.3 Numerical Experiment 466
62.4 Results and Discussion 467
References 470
Chapter 
471 
63.1 Introduction 471
63.2 Description of Australian Data 471
63.2.1 
471 
63.2.2 
472 
63.2.3 
472 
63.2.4 
472 
63.3 Results 472
63.3.1 
472 
63.3.2 
473 
63.3.3 
475 
63.3.4 
476 
63.4 Conclusion 477
References 477
Chapter 
478 
64.1 Introduction 478
64.2 Data Sets 479
64.2.1 
479 
64.2.2 
480 
64.2.3 
480 
64.2.4 
480 
64.2.5 
481 
64.3 Pointwise Tests 482
64.4 Baseline Tests 484
64.5 Conclusions 485
References 485
Chapter 
486 
65.1 Introduction 486
65.2 Target Area 487
65.3 Comparisons with a Regional High-Resolution Geoid Model BALTgeoid-04 487
65.3.1 
487 
65.3.2 
488 
65.3.3 
488 
65.3.4 
489 
65.4 Comparisons with the Terrestrial Data 490
65.5 Comparisons with GPS-Levelling Data 491
65.6 Summary and Conclusions 492
References 493
Chapter 
494 
66.1 Introduction 494
66.2 Data Processing 494
66.2.1 
495 
66.2.2 
496 
66.2.2.1 
496 
66.3.2.2 Proof of Concept 497
66.3 Validation Results 498
66.3.1 
498 
66.3.2 
499 
66.4 Conclusions 500
References 500
Chapter 
502 
67.1 Introduction 502
67.2 Scandinavia and Adjacent Areas 502
67.3 Greenland 504
67.4 Conclusions 506
References 506
Chapter 
507 
68.1 Introduction 507
68.2 LS Approach for Data at Ground Level and Satellite Coefficients 508
68.3 From Least Squares to Galerkin 509
68.4 Comparison with Pull-Back and Downward Continuation Procedures 511
68.5 Some Conclusions and Open Issues 513
References 513
Part VII Temporal Gravity Changes and Geodynamics 514
Chapter 
515 
69.1 Introduction 515
69.2 The HYDROGRAV Project 516
69.3 Preliminary Results for the Okavango Delta 516
69.3.1 
517 
69.3.2 
518 
69.4 Summary 518
References 519
Chapter 
521 
70.1 Introduction 521
70.2 Data and Methods 522
70.2.1 
522 
70.2.2 
522 
70.2.3 
523 
70.3 Mass Change Results 524
70.4 Conclusion 525
References 525
Chapter 71 Water Level Temporal Variation Analysis at Solimoes and Amazonas Rivers 527
71.1 Introduction 527
71.2 Ocean-Atmosphere Interactions 528
71.3 Orthometric Height of the Water Surface 529
71.3.1 
529 
71.3.2 
529 
71.4 Results and Discussion 529
71.5 Conclusions 531
References 532
Chapter 
533 
72.1 Introduction 533
72.2 Methodology 533
72.3 Description of Data Sets 534
72.3.1 
534 
72.3.2 
535 
72.4 Analysis of Results 535
72.4.1 
535 
72.4.2 
536 
72.4.3 
537 
72.5 Conclusions 538
References 539
Chapter 
541 
73.1 Introduction 541
73.2 Data and Methodology 542
73.2.1 
542 
73.2.2 
542 
73.3 Interpretation of the Results 543
73.3.1 
543 
73.3.2 
544 
73.4 Conclusions 547
References 549
Chapter 
550 
74.1 Introduction 550
74.2 Estimation of Gravity Residuals 550
74.2.1 
551 
74.2.2 
551 
74.3 Estimation of Gravity Change Associated with Antarctic Ice Sheet Mass Change 551
74.3.1 
551 
74.3.2 
552 
74.4 Comparisons of Observed Gravity Residuals with Expected Gravity Changes 553
74.5 Summary 554
References 555
Chapter 
556 
75.1 Introduction 556
75.2 GRACE 557
75.2.1 
557 
75.2.2 The Influence 
557 
75.2.3 
558 
75.3 
559 
75.3.1 
559 
75.3.2 
560 
75.3.3 
560 
75.4 Mass Change Estimates 561
75.5 Summary 561
References 562
Chapter 
563 
76.1 Introduction 563
76.2 Data and Processing 564
76.2.1 
564 
76.2.2 
564 
76.2.3 
566 
76.3 Results 566
76.4 Discussion 567
References 568
Chapter 
570 
77.1 Introduction 570
77.2 Methodology on the Optimal Filter Design 571
77.3 Procedure 571
77.4 Hydrological Modeling 572
77.5 Results 572
77.6 Conclusions 576
References 576
Chapter 
578 
78.1 Introduction 578
78.2 Data Sets 579
78.2.1 
579 
78.2.2 
579 
78.2.3 
580 
78.3 Analysis Method 581
78.4 Results 581
78.4.1 
581 
78.4.2 
582 
78.4.3 Degree 1 and the C2,0 Coefficient 582
78.5 Conclusions 583
References 584
Chapter 
585 
79.1 Introduction 585
79.2 Secular Trends 586
79.3 Seasonal Variations 587
79.4 Selected Time Series 589
79.5 Conclusions 591
References 592
Chapter 
593 
80.1 Hydrology and GRACE 593
80.2 Data and Methodology 594
80.2.1 
594 
80.2.2 
595 
80.3 Stochastics of the Data 595
80.4 Results and Discussion 596
80.4.1Hydrology- 
596 
80.4.2 
597 
80.4.3 
598 
80.5.4 Discussion 598
80.5 Summary and Outlook 599
References 599
Chapter 81 Secular Geoid Rate from GRACE for Vertical Datum Modernization 601
81.1 Introduction 601
81.2 Methodology 602
81.3 Tailoring the Filter 604
81.4 Discussion 604
References 606
Chapter 
608 
82.1 Introduction 608
82.2 Processing Strategy 609
82.2.1 
609 
82.2.2 
609 
82.2.3 
609 
82.3 Results 610
82.4 Conclusions 611
References 612
Part VIII Earth Observation and the Global Geodetic Observing System (GGOS) 613
Chapter 
614 
83.1 GGP Stations 614
83.2 A Typical GGP Site 615
83.3 Performance of the SG 615
83.4 How GGP Functions 616
83.5 GGP and GGOS 618
83.5.1 
618 
83.5.2 
619 
83.5.3 
619 
83.5.4 
621 
83.6 Other GGP Projects 621
83.7 Conclusions 622
References 622
Chapter 
623 
84.1 Introduction 623
84.2 Method 624
84.2.1 
624 
84.2.2 
624 
84.3 Results 625
84.3.1 
625 
84.3.2 
626 
84.3.3 
626 
84.4 Conclusions 627
References 627
Chapter 
629 
85.1 Introduction 629
85.2 A Unified Approach 630
85.2.1 
630 
85.2.2 
631 
85.2.3 
631 
85.2.4 
632 
85.3 Discussion and Summary 634
References 634
Chapter 
636 
86.1 Introduction 636
86.2 Modeling Loading Contributions 637
86.2.1 
637 
86.2.2 
639 
86.3 Observations of GPS Sites Positions 639
86.3.1 
639 
86.3.2 
640 
86.4 Integration of the AOH Loading Model: Comparison of Two GPS Solutions 641
86.4.1 
642 
86.4.2 
643 
86.5 Conclusion 643
References 644
Chapter 
645 
87.1 Introduction 645
87.2 Methodology Followed 646
87.2.1 
646 
87.2.2 
646 
87.2.3 
647 
87.3 Data Analysis 648
87.3.1 
648 
87.3.2 
648 
87.4 Conclusions Further Research 652
References 652
Chapter 
653 
88.1 Introduction 653
88.2 Data Processing 654
88.2.1 
654 
88.2.2 
655 
88.2.3C20 
655 
88.2.4 
656 
88.3 Comparisons of .C20 Estimates 656
88.4 Conclusions 657
88.5 Discussion 658
References 660
Part IX Geodetic Monitoring of Natural Hazards and a Changing Environment 661
Chapter 
662 
89.1 Introduction 662
89.2 Data and Processing 662
89.3 Observation Results 663
89.4 Modeling Results and Discussion 663
References 669
Chapter 
671 
90.1 Introduction 671
90.2 Description of Data 672
90.2.1 
672 
90.2.2 
673 
90.3 Assessment of Absolute Vertical Accuracy of LiDAR Data 673
90.4 Assessment of Relative Vertical Accuracy of LiDAR Data 674
90.5 Improving the Interpolation Performance in Areas with Occlusions 675
90.6 Conclusions 676
References 676
Chapter 
678 
91.1 Introduction 678
91.2 Segmentation Approach 678
91.2.1 
678 
91.2.2 
679 
91.2.3 
679 
91.2.3.1 
680 
91.3.3.2 
680 
91.3.3.3 Third Segmentation Level 680
91.3 Conclusions 681
References 682