GLACIER FLOW AND TOPOGRAPHY MEASUREMENTS WITH TERRASAR-X AND TANDEM-XM. Eineder 1), W. Abdel Jaber2), D. Floricioiu1), H. Rott3), N. Yague-Martinez1)
1)German Aerospace Center, 2)Technische Universität München,3)Universität Innsbruck
IGARSS 2011
Remote Sensing Technology Institute 2
Drygalski Glacier, Antarctica
From: Rott et al. EUSAR 2008
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Drygalski Glacier after Collapse of Larsen A
Photo: H. Rott
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TerraSAR-X and TanDEM-X Observations
-500
-400
-300
-200
-100
0
100
200
300
400
500
06.08.2007 22.02.2008 09.09.2008 28.03.2009 14.10.2009 02.05.2010 18.11.2010
Date (Master of Correlation Pair)
Eff
. b
ase
line
[m
]
TanDEM-X TerraSAR-X
Preliminary TanDEM-X
DEMs
TS-X 11 day intervall series TS-X 3 repetitions11 day intervall
Stripmap mode, nominal resolution < 3 m
Video of 2007-2008 Time Series (30 Frames)
Maybe zooms to different interesting spots
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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 2562 pixels (320m)2
Speckle Feature
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Velocity Estimation – Systematic Errors (Bias)
Orbit error
Timing error
Atmosphere
Solid Earth tides } ( ) 12
, 5.211
202 −=< dcm
d
cmpropvelσ
See Eineder et al., Imaging Geodesy—Toward Centimeter-Level Ranging Accuracy With TerraSAR-X, IEEE TGRS 2010
} ( ) 12
, 64.011
52 −=< dcm
d
cmsystemvelσ
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Velocity Estimation – Random Errors
Feature correlation:
DEM error:
Total = random + systematic error:
) 200, 630, 200(
1sin11
1 1,
mkmRmB
dcmR
B
d
DEM
DEMDEMvel
==<
≈=
⊥
−⊥
σθ
σσ
12
, 11
2
32
11
1 3 −≈
−= dcm
Ndm
effcorrvel γπ
γσ
-12,
2,
2,
2, d cm 9.2=+++ DEMvelcorrvelpropvelsystemvel σσσσ
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Average Three-Year Velocity Map
0.0
6.0
[m/d
]
5 km AC
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5,00
5,20
5,40
5,60
5,80
6,00
6,20
6,40
0,00 0,50 1,00 1,50 2,00 2,50 3,00
Time [years] - 08-OCT-2007
Ve
loci
ty [
m/d
]
Temporal Velocity Profile at Point A (Terminus)
Linear fit 2007-2010: -0.166 md-1a-1
Linear fit 2007/2008: -0.336 md-1a-1
Sum
mer
Winter
Sum
mer
Winter
Sum
mer
Winter
Significant seasonal variations and decelleration
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0,90
0,95
1,00
1,05
1,10
1,15
1,20
0,0 0,5 1,0 1,5 2,0 2,5 3,0
Time [years] - 08-OCT-2007
Vel
ocity
[m/d
]
Temporal Velocity Profile at Point C
Sum
mer
Winter
Sum
mer
Winter
Sum
mer
Winter
Measurements confirm error margin (residuals stdev. < 2 cm d-1) slight seasonal variations, maybe decelleration
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One-Year Deceleration Map
AC
-0.4
0.4
[md
-1a-1
]
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Three-Year Deceleration Map
AC
-0.4
0.4
[md
-1a-1
]
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Average Spatial Correlation Coefficient
0.0
0.7
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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
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Shaded DEM and 20 m Contour Lines
Terminus
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Drygalski Glacier Terminus Height Profile
(Small Baseline DEM)
70 m ~460 m
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Difference TanDEM-X (asc) – GLOBE DEM
300 m
-300 m
0 m
1. Height loss (?), 2. Velocity and geocoding errors
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TanDEM-X DEM Roughness Map
Roughnes map
0.0
3.0
σh [m]
Roughness based on 10 x 10 pixel plane residuals (50 x 50 m2)
Coincides with correlation map, confirms DEM quality
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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-1a-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
