List of Figures s3

LIST OF FIGURES PAGE Figures follow at the end of each chapter.

Figure 1.1: Site maps...... 7 Figure 3.1: The electromagnetic spectrum...... 13 Figure 3.2: Operating principle of a SAR...... 15 Figure 3.3: Real antenna positions forming a synthetic aperture...... 17 Figure 3.4: Effect of pulse length...... 19 Figure 3.5: Slant and ground range...... 22 Figure 3.6: SAR geometric distortions...... 22 Figure 3.7: Diffuse, specular, corner, and volume reflection...... 24 Figure 3.8: Benson's generalized cross-section of glacier facies...... 34 Figure 4.1: ERS-2 and Radarsat look angles...... 38 Figure 4.2: Optical depth vs. actual depth...... 38 Figure 4.3: Snow stakes on Commonwealth and Howard Glaciers...... 39 Figure 4.4: Digital Elevation Model (DEM) of Southern Victoria Land...... 43 Figure 4.5: Ray diagrams of the reflections in a dihedral and a triangular trihedral corner reflector...... 45 Figure 4.6: Inclination angle...... 45 Figure 4.7: A trihedral corner reflector...... 47 viii

Figure 4.8: Ice surface roughness measured from a 2 m bar to the ice surface...... 51 Figure 5.1: ERS-2 uncorrected SAR...... 54 Figure 5.2: Radarsat uncorrected SAR...... 55 Figure 5.3: The portion of Taylor Valley that was imaged by ERS-2...... 57 Figure 5.4: Surface characteristics along the transect on Commonwealth Glacier...... 59 Figure 5.5: Photographs of Commonwealth and Howard Glaciers...... 60 Figure 5.6: Cryoconite hole...... 61 Figure 5.7: Snow depths along the transect on Commonwealth Glacier...... 63 Figure 5.8: Sky and Water I...... 63 Figure 5.9: Snow stakes, radar reflectors, transect route, and sample sites on Commonwealth Glacier...... 63 Figure 5.10: Snow layers graph...... 64 Figure 5.11: Averaged snow depths along the transect on Howard Glacier..66 Figure 6.1: Effect of a SAR beam scattering off specular surfaces of different incidence angles...... 70

Figure 6.2: Intermediate Terrcorr images of Commonwealth Glacier...... 73 Figure 6.3: Auto and un-corrected ERS-2 SAR of Commonwealth Glacier.74 Figure 6.4: Terrain and un-terrain corrected Radarsat ScanSAR...... 76 Figure 6.5: ERS-2 terrain corrected SAR...... 77 Figure 6.6: Radarsat terrain corrected SAR...... 79 Figure 6.7: Auto- and manual-correlation terrain correction of Commonwealth Glacier and surrounding area...... 82 Figure 6.8: ERS-2 SAR of Commonwealth Glacier and surrounding area...86 ix

Figure 6.9: Slope and elevations (from DEM) of Commonwealth Glacier...87 Figure 6.10: ERS-2 SAR of Commonwealth Glacier with elevation contours...... 88 Figure 6.11: Manually-correlated and uncorrected ERS-2 SAR of Commonwealth Glacier...... 90 Figure 6.12: Terrain and un-corrected Radarsat ScanSAR of Howard Glacier...... 94 Figure 6.13: SAR local incidence angles...... 95 Figure 7.1: Corrected SAR brightness and surface measurements along the transect...... 98 Figure 7.2: SAR image brightness relative to surface elevation...... 99 Figure 7.3: Commonwealth Glacier ERS-2 SAR 1/15/1999 snow measurement locations...... 99 Figure 7.4: ERS-2 brightness to snow depth graph...... 100 Figure 7.5: Commonwealth Glacier ERS-2 SAR snowline classification maps...... 102 Figure 7.6: Comparison of Commonwealth Glacier...... 105

Figure 7.7: Detail of snowline on Commonwealth Glacier ERS-2 SAR...... 108 Figure 7.8: Enhanced volume backscatter...... 111 Figure 7.9: Commonwealth Glacier snow stratigraphy...... 112 Figure 7.10: Reflections and primary refractions of the SAR beam at stake 12...... 115 Figure 7.11: Uncorrected brightness comparison (along the transect) between Radarsat and ERS-2...... 118 Figure 7.12: Terrain corrected SAR image transect locations...... 119 x

Figure 7.13: Comparison of corrected and uncorrected brightness values along the transect...... 120 Figure 7.14: Corrected brightness comparison (along the transect) between Radarsat and ERS-2...... 122 Figure 7.15: Howard Glacier snow layers graph...... 125 Figure 7.16: Landsat and Radarsat comparison of Howard Glacier snowline...... 127 Figure 7.17: Six SAR views of Commonwealth Glacier...... 129 Figure 7.18: The terminus of Canada Glacier as represented by six SAR images...... 131 Figure 7.19: Aerial photo of Canada Glacier taken November 1993...... 132 Figure 7.20: Images of Taylor Glacier...... 134 Figure 7.21: Ripples on the upper Taylor Glacier as represented by four SAR images and one Landsat...... 135 Figure 7.22: Lower Taylor Glacier as represented by five SAR images...... 136 Figure 7.23: Radarsat ScanSAR image transect of the centerline of Taylor Glacier...... 137

Figure 7.24: Comparison of backscatter of lake surfaces by season...... 139