1. Mass Deficit of Glaciers at the Northern
Antarctic Peninsula derived from Satellite-
borne SAR and Altimeter Measurements
Helmut Rott1,2, Florian Müller1, Thomas Nagler1
Dana Floricioiu3, Michael Eineder3
1 ENVEO IT GmbH, Innsbruck, Austria
2 Institute for Meteorology & Geophysics, Univ. Innsbruck
3 DLR-IMF, Oberpfaffenhofen
H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula

2. Contents of Presentation
• The Scientific Question: Glacier contributions to sea level rise after
ice shelf disintegration
• Data sources and method
• Overview on Collapse of Larsen-A and-B Ice Shelf
• Example for acceleration of glaciers after collapse: Crane Glacier
• Dynamic thinning by ICESat altimetry and mass continuity
• The contribution to sea level rise
H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula

3. The Mass Balance of Grounded Ice is relevant for
Sea Level Rise
The main export of
Antarctic ice is routed
through ice shelves and
lost by iceberg calving.
BC
The contribution to sea level rise is determined by the imbalance of net
accumulation, BA, on grounded ice minus the export through a cross
section at the grounding line or calving front, BC: BN = BA – BC
Satellite observations provide key input for computing BC:
• The ice velocity at the cross section, v(y) Bc v ( y) H ( y) dy
• The surface elevation at the front (by altimetry, SAR) Y
enabling to estimate ice thickness H
H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula

4. Investigation of Mass Imbalance of Glaciers
• The Question:
The response and mass imbalance of glaciers after disintegration of
northern LIS: Prince Gustav Channel (PCG), Larsen-A, Larsen-B
• Data sources:
Precise maps of ice velocity for all glaciers:
- Pre-collapse ERS-1/ERS-2 tandem interferometry (1day repeat) 1995-99
- TerraSAR-X (2m res.) incoherent amplitude correlation 2007-2010
ICESat profiles (repeat pass) near grounding line for a few glaciers
Ice thickness of Crane Glacier: Bathymetry in fjord and airborne sounder
(CReSIS, Univ. Kansas) 2002, 2004, 2009, 2010 (ambiguous signals)
Bathymetry in front of Crane Glacier 2006 (Zgur et al.)
Approach:
Compute fluxes across gate near 2008 ice front
Pre-collapse state of glaciers close to balance V(1999) = V(1995)
Pre-collapse net balance from flux Fy (1995,1999)
Post-collapse Fy refers to 2008-09, taking into account thinning
H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula

5. Retreat of Grounded Ice after Ice Shelf Collapse
Hektoria - Evans – Green
Glacier Larsen IS, AA
ASAR WSM
22 March 07
H. Rott, T. Nagler
H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula

6. Deformation Pattern of Hektoria-Green-Evans Glaciers
TerraSAR-X 28 March 2008
H. Rott, T. Nagler
H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula

7. Mass fluxes for
glaciers in Larsen-B
embayment
Drainage basins and
calving gates
Landsat
March 1986
H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula

8. TerraSAR-X Data Set for Ice Velocities of Larsen Glaciers
Method:
Motion mapping by
incoherent amplitude
correlation
• Provides 2 components
of velocity Vector
• Requires persistent
features
• Does not require
coherence
• Accuracy < 5 cm/day (with
11- day repeat pass)
• Apply multiple pairs: 11-,
22-, 33- , ….. days
70 Stripmap Scenes, June 2007 – Jan. 2010, 11-day repeat pass (multiple)
H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula

9. Ice Motion Retrieval – Example for Crane Glacier
Frontal Velocity 1995 1.7 m/d ERS InSAR
2007 7.2 m/d TerraSAR-X
TerraSAR-X 18-29/10/2008
Decorrelates on fast glacier
ERS Tandem 1995/10/31-1995/11/01
Amplitude correlation for V
1 day repeat pass – good coherence
H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula

10. TerraSAR-X Crane Glacier,
H. Rott IGARSS 2011 Oct. 2008 – Nov. 2009
Mass Deficit Glaciers Antarctic Peninsula

11. TerraSAR-X Velocity Profiles – Crane Glacier
P1 P2
Profiles for computing calving flux (P1) and dynamic thinning (P2, P1).
H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula

12. Ice Thickness and Dynamic Thinning
v1
h1
w1
P1
v2
h2
Surface lowering at P2 observed by ICESat P2
w2
Flux divergence between 2 cross
2008 sections Surface lowering (mass
continuity)
1999
h u v h h
b h u v
t x y x y
Cross section at P1, base extrapolated from
bathymetry(Zgur et al., 2007)
H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula

13. Discharge of Glaciers in Larsen-B Embayment
Glacier Gate Area Vc (m/yr) Discharge (Gt/yr)
km2
1995/99 2008 1995/99 2008 Mass Deficit
Hektoria- H1, 1091 387 1545 1.186 2.878 1.692 0.641
Green G1
Evans E1 E2 210 93 474 0.144 0.459 0.315 0.099
Punchbowl PU1 102 65 183 0.058 0.155 0.097 0.034
Jorum N J2 56 68 146 0.042 0.082 0.040 0.019
Jorum S J1 318 475 865 0.346 0.534 0.188 0.131
Crane C1 1057 548 1882 1.149 2.919 1.770 0.614
Mapple MA1 165 46 82 0.061 0.109 0.048 0.026
Melville ME1 218 73 201 0.076 0.198 0.122 0.044
Pequod PE1 212 66 135 0.074 0.145 0.071 0.034
Sum 3327 3.136 7.479 4.343
0.537 1.542 1.642
H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula

14. Glaciers of Northern LIS – Contribution to Sea Level Rise
Retreat of Grounded Ice since 1995 Total
:
Glacier/Region Area [km²] Area [km²] Area [km²] 1995- Decrease in Ice Shelf
1999 2003 2004 2008 Area Northern LIS
Röhss Bay - 8 8 35 1995-2007
S-B Gl. 24 54 54 67
13 000 km2
D-B-E Gl. 34 39 35 46
Gl. N. CW - 23 23 33
Drygalski Gl. 24 32 32 35 S-B Sjögren-Boydell
H-G-E Gl. - 57 41 119 D-B-E Dinsmoor-Bombardier-Edgeworth
Crane-JorumGl. - 3 22 31 H-G-E Hektoria-Green-Evans
Total Retreat of Grounded Ice Area 1995 -2008: 360 km2
Retreat of Grounded Ice March 2002 to 2008: 250 km²
g 0.06 mm SLE (sea level equivalent, assuming 80 m height above buoyancy)
Sea level equivalent contribution due to export at glacier fronts 2002 – 2008,
Larsen A and B: 0.03 mm/a.
Total SLE (2002-2008) 0.04 0.01 mm/a (ca. 3% of eustatic SLR)
H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula

15. • The rapid disintegration of Northern Larsen Ice Shelf demonstrates the
high sensitivity of polar ice masses to climate change – the retreat
proceeding faster than predicted by models.
• Repeat-pass SAR data offer unique capabilities to study flow dynamics of
glaciers and ice streams with great detail. In synergy with precise surface
topography (altimetry, TanDEM-X) mass balance can be retrieved.
• The sea level contribution of the glaciers above Larsen-A and -B is not
very significant, but the studies are important for predicting the dynamic
response of large ice masses if warming spreads further south.
H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula