Abstract ........................................................ 3
Zusammenfassung ................................................. 5
Contents ........................................................ 7
1 Introduction .............................................. 10
1.1 Scientific motivation ..................................... 10
1.2 Research objectives ....................................... 14
1.3 Thesis outline ............................................ 15
2 SAR and InSAR basics ...................................... 17
2.1 Synthetic aperture radar .................................. 17
2.1.1 Backscattering coefficient ......................... 19
2.1.2 SAR images ......................................... 20
2.2 SAR interferometry ........................................ 22
2.2.1 Interferometrie phase .............................. 22
2.2.2 Coherence .......................................... 23
2.2.3 Interferometrie phase statistics ................... 24
3 Glaciology basics ......................................... 26
3.1 Physical properties of snow ............................... 26
3.2 Surface characteristics ................................... 27
3.3 Glacier zones ............................................. 27
3.3.1 Snow to ice transformation and density variation
with depth ......................................... 29
3.4 Glacier flow .............................................. 29
3.5 Glacier mass balance ...................................... 32
3.5.1 Methods to estimate the glacier mass balance ...... 34
4 Microwave properties of snow and ice ...................... 37
4.1 Electromagnetic waves basics .............................. 37
4.2 Scattering ................................................ 39
4.2.1 Reflection and transmission ........................ 39
4.2.2 Surface and volume scattering ...................... 40
4.3 Dielectric propenies of snow .............................. 40
4.4 Extinction coefficient and penetration depth .............. 43
4.5 Microwave backscattering of snow .......................... 44
4.5.1 Remote sensing applications based on snow
backscattering ..................................... 44
4.5.2 Models of backscattering coefficient ............... 45
4.5.3 Experimental observations of backscattering ........ 46
5 The Northern and Southern Patagonian icefields ............ 52
5.1 Geographiсal setting ...................................... 52
5.2 Glacier inventory ......................................... 52
5.3 Climate ................................................... 53
5.4 Areal changes ............................................. 55
5.5 Local ice thickness changes ............................... 56
5.6 Large-scale remote sensing studies ........................ 57
5.7 Other relevant studies .................................... 58
6 Elevation and other datasets .............................. 60
6.1 SRTM ...................................................... 60
6.1.1 SRTM validation and accuracy ....................... 63
6.1.2 SRTM data used ..................................... 65
6.2 TanDEM-X .................................................. 66
6.2.1 The TanDEM-X mission ............................... 66
6.2.2 Integrated TanDEM-X Processor and Raw DEMs ......... 70
6.2.2.1 Bistatic SAR processing ........................ 71
6.2.2.2 Interferometrie processing ..................... 72
6.2.3 TanDEM-X accuracy and validation ................... 75
6.2.3.1 Systematic errors .............................. 76
6.2.3.2 Baseline calibration ........................... 77
6.2.4 TanDEM-X dataset used .............................. 77
6.2.4.1 SPI data ....................................... 77
6.2.4.2 NPI data ....................................... 78
6.3 Glacier outline and additional data ....................... 82
7 Ice elevation change maps ................................. 84
7.1 Dealing with phase unwrapping errors ...................... 84
7.2 Vertical and horizontal coregistration of the DEMs ........ 86
7.2.1 Determination of the Raw DEM height offset and
its accuracy ....................................... 87
7.3 Elevation change maps derivation .......................... 92
7.4 Results and discussion .................................... 92
8 SAR Backscattering and penetration depth ................. 101
8.1 Backscattering analysis of snow .......................... 101
8.2 Surface condition during SRTM ............................ 103
8.2.1 Processing the SRTM backscattering ................ 103
8.2.2 Meteorological conditions during SRTM ............. 105
8.2.3 Interpretation of the SRTM backscattering ......... 106
8.3 Surface condition during TanDEM-X acquisitions ........... 109
8.3.1 Processing the TanDEM-X backscattering ............ 109
8.3.2 Meteorological conditions in NPI during TanDEM-X
acquisitions ...................................... 111
8.3.3 Interpretation of the TanDEM-X backscattering
of NPI ............................................ 112
8.3.4 Analysis of the TanDEM-X backscattering of SPI .... 114
8.4 Seasonal comparison of σ° and surface elevation .......... 117
9 Geodetic mass balance .................................... 121
9.1 Geodetic mass balance state of the art ................... 121
9.1.1 Error budget: general approach and state of the
art .................................................... 123
9.1.1.1 Uncertainty of the elevation difference
sample ........................................ 123
9.1.1.2 Geostatistics and semivariograms .............. 126
9.1.1.3 Uncertainty of the spatially averaged
elevation difference .......................... 129
9.1.1.4 Ice density profile uncertainty ............... 132
9.1.1.5 Extrapolation to unsurveyed areas ............. 134
9.1.1.6 Dealing with radar signal penetration in ice
and snow ...................................... 134
9.1.1.7 Bias due to different resolution of the DEMs .. 137
9.1.1.8 Other sources of uncertainty .................. 138
9.2 Mass balance derivation .................................. 140
9.3 Mass balance uncertainty estimation ...................... 142
9.3.1 Influence of the different resolution of the
DEMs .............................................. 142
9.3.2 Estimation of the uncertainty of the elevation
difference sample ................................. 145
9.3.3 Interferometrie uncertainty: surface type
comparison ........................................ 151
9.3.4 Spatial correlation analysis ...................... 153
9.3.5 Standard error of the spatial average ............. 157
9.3.6 Uncertainty of the DEM registration procedure ..... 158
9.3.7 Error due to seasonal elevation changes and
signal penetration ................................ 158
9.3.8 Crustal uplift due to glacial isostatic
adjustment ........................................ 160
9.3.9 Other error sources and combination of
uncertainties ..................................... 160
9.3.10 Mass balance error budget for NPI and SPI ......... 162
9.4 Frontal and subaqueous ice changes ....................... 162
9.5 Mass balance results ..................................... 167
10 Multitemporal geodetic mass balance of the Jorge Montt
Glacier .................................................. 174
11 Glacier surface velocity ................................. 179
11.1 State of the art X ...................................... 179
11.2 Objectives and data ...................................... 181
11.2.1 TerraSAR-X data ................................... 182
11.2.2 Approach .........................................
11.3 Methodology .............................................. 184
11.3.1 Data selection and cropping ....................... 184
11.3.2 Shift estimation through incoherent cross-
correlation ....................................... 184
11.3.3 Outliers rejection and interpolation .............. 187
11.4 Accuracy ................................................. 189
11.4.1 Accuracy of the differential shift estimation
through cross-correlation ......................... 189
11.4.2 Pixel localization accuracy ....................... 190
11.4.2.1 Error due to the propagation in the
atmosphere .................................... 191
11.4.2.2 Error due to geocoding ........................ 194
11.4.3 Error due to the deformation of the Earth ........ 195
11.5 Results .................................................. 198
11.5.1 NPI and SPI ....................................... 198
11.5.2 Antarctica ........................................ 199
11.5.2.1 Drygalski Glacier ............................. 201
11.5.2.2 Nimrod and Byrd glaciers ...................... 203
11.5.2.3 Glaciers of the Gould and Amundsen Coast ...... 206
11.5.2.4 Thwaites Glacier .............................. 206
11.5.2.5 Recovery Glacier .............................. 209
12 Conclusion ............................................... 211
12.1 Discussion and conclusion ................................ 211
12.2 Outlook X ................................................ 213
Bibliography .................................................. 215
Acknowledgements .............................................. 236
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