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

2. H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula 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

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

4. H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula 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 F y (1995,1999) Post-collapse F y refers to 2008-09, taking into account thinning

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

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

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

8. H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula TerraSAR-X Data Set for Ice Velocities of Larsen Glaciers  70 Stripmap Scenes, June 2007 – Jan. 2010, 11-day repeat pass (multiple) 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

9. H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula 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 Amplitude correlation for V Ice Motion Retrieval – Example for Crane Glacier ERS Tandem 1995/10/31-1995/11/01 1 day repeat pass – good coherence

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

11. H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula TerraSAR-X Velocity Profiles – Crane Glacier P1P2 Profiles for computing calving flux (P1) and dynamic thinning (P2, P1).

12. H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula Ice Thickness and Dynamic Thinning Surface lowering at P2 observed by ICESat Flux divergence between 2 cross sections  Surface lowering (mass continuity) Cross section at P1, base extrapolated from bathymetry(Zgur et al., 2007) 2008 1999

13. H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula GlacierGate Area km 2 V c (m/yr)Discharge (Gt/yr) 1995/9920081995/992008 Mass Deficit Hektoria- Green H1, G1 109138715451.1862.878 1.692  0.641 EvansE1 E2210934740.1440.459 0.315  0.099 PunchbowlPU1102651830.0580.155 0.097  0.034 Jorum NJ256681460.0420.082 0.040  0.019 Jorum SJ13184758650.3460.534 0.188  0.131 CraneC1105754818821.1492.919 1.770  0.614 MappleMA116546820.0610.109 0.048  0.026 MelvilleME1218732010.0760.198 0.122  0.044 PequodPE1212661350.0740.145 0.071  0.034 Sum 3327 3.136  0.537 7.479  1.542 4.343  1.642 Discharge of Glaciers in Larsen-B Embayment

14. H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula Retreat of Grounded Ice since 1995 : S-B Sjögren-Boydell D-B-E Dinsmoor-Bombardier-Edgeworth H-G-E Hektoria-Green-Evans Total Retreat of Grounded Ice Area 1995 -2008: 360 km 2 Retreat of Grounded Ice March 2002 to 2008: 250 km²  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) Decrease in Ice Shelf Area Northern LIS 1995-2007 13 000 km 2 Total 1995- 2008 35 67 46 33 35 119 31 Glaciers of Northern LIS – Contribution to Sea Level Rise

15. H. Rott IGARSS 2011 Mass Deficit Glaciers Antarctic Peninsula 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.