1) The document analyzes glacier flow measurements of Drygalski Glacier in Antarctica using TerraSAR-X and TanDEM-X satellite radar imagery over multiple years. 2) Velocity mapping found seasonal variations in flow at the glacier terminus, as well as a possible slight deceleration between 2007-2010. 3) Preliminary TanDEM-X DEMs were produced and compared to other data, finding height errors within expectations over the glacier area. The DEMs provide useful data on glacier thickness and roughness.

1. GLACIER FLOW AND TOPOGRAPHY MEASUREMENTS WITH TERRASAR-X AND TANDEM-X M. Eineder 1 ) , W. Abdel Jaber 2) , D. Floricioiu 1) , H. Rott 3) , N. Yague-Martinez 1) 1) German Aerospace Center, 2) Technische Universität München, 3) Universität Innsbruck IGARSS 2011

2. Drygalski Glacier, Antarctica From: Rott et al. EUSAR 2008

3. Drygalski Glacier after Collapse of Larsen A Photo: H. Rott

4. TerraSAR-X and TanDEM-X Observations Preliminary TanDEM-X DEMs TS-X 11 day intervall series TS-X 3 repetitions 11 day intervall Stripmap mode, nominal resolution < 3 m

5. Video of 2007-2008 Time Series (30 Frames) Maybe zooms to different interesting spots

6. Velocity Analysis Method 11 day intervalls Incoherent (amplitude) image correlation technique Use of geocoded standard products, 1.25 m spacing, 1.3 looks 2D shift measurement Absolute displacement  no tie-points, no phase ambiguity Chip size 256 2 pixels (320m) 2 Speckle Feature

7. Velocity Estimation – Systematic Errors (Bias) Orbit error Timing error Atmosphere Solid Earth tides See Eineder et al., Imaging Geodesy—Toward Centimeter-Level Ranging Accuracy With TerraSAR-X, IEEE TGRS 2010

8. Velocity Estimation – Random Errors Feature correlation: DEM error: Total = random + systematic error:

9. Average Three-Year Velocity Map 0.0 6.0 [m/d] 5 km A C

10. Temporal Velocity Profile at Point A (Terminus) Linear fit 2007-2010: -0.166 md -1 a -1 Linear fit 2007/2008: -0.336 md -1 a -1 Summer Winter Summer Winter Summer Winter  Significant seasonal variations and decelleration

11. Temporal Velocity Profile at Point C Summer Winter Summer Winter Summer Winter  Measurements confirm error margin (residuals stdev. < 2 cm d -1 )  slight seasonal variations, maybe decelleration

12. One-Year Deceleration Map A C -0.4 0.4 [md -1 a -1 ]

13. Three-Year Deceleration Map A C -0.4 0.4 [md -1 a -1 ]

14. Average Spatial Correlation Coefficient 0.0 0.7

15. Two Preliminary TanDEM-X DEMs Available Descending 2010-10-21 Beff=180.2 m H/2PI=-46.08 m Ascending 2010-12-11 Beff=26.0 m H/2PI=-323.2  Used both DEMs for height offset determination  Used descending DEM for analysis

16. Shaded DEM and 20 m Contour Lines Terminus

17. Drygalski Glacier Terminus Height Profile (Small Baseline DEM) 70 m  ~460 m

18. Difference TanDEM-X (asc) – GLOBE DEM 300 m -300 m 0 m  1. Height loss (?), 2. Velocity and geocoding errors

19. TanDEM-X DEM Roughness Map Roughnes map 0.0 3.0 σ h [m] Roughness based on 10 x 10 pixel plane residuals (50 x 50 m 2 )  Coincides with correlation map, confirms DEM quality

20. Conclusions Demonstrated multi-year feature tracking on glacier with 3 cmd -1 accuracy over larger areas Acceleration since 1995 confirmed again Detected strong seasonal variations ( ±0.4 md -1 ) at terminus Hints for slight (-0.166 md -1 a -1 ) deceleration 2007-2010 at terminus TanDEM-X DEM height errors within expectations over glacier TanDEM-X DEM roughness predicts feature correlation quality TanDEM-X DEM useful for terminus height / thickness estimation