1. Multitemporal, Multisensor Fusion for Monitoring Ice Sheet Changes from Altimetry Bea Csatho, Toni Schenk, Sudhagar Nagarajan and Greg Babonis, University at Buffalo, SUNY, Buffalo, NY, USA
2. Motivation: Sea Level Rise and Ice Sheet Mass Balance IGARSS July 2011, Vancouver, Canada The red curve is based on tide gauge measurements . The black curve is the altimetry record (zoomed over the 1993–2009 time span) . (Nicholls and Cazenave, Science 2010) IPCC AR4, A1F1 model Sea level rise estimates, including the effect of ice dynamics
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5. Geodetic Method/Altimetry IGARSS July 2011, Vancouver, Canada Mass balance estimated from change of ice sheet surface elevation Level up, mass balance increase Level down, mass balance decrease
17. Examples of h(t) Computation: Accumulation Zone, h=2566 m IGARSS July 2011, Vancouver, Canada average dh/dt= 0.12 m/yr 2003 2004 2005 2006 2007 2008 -0.7 0 0.4 dh(m)
18. Examples of dh/dt Computation: Ablation Zone: 1241 m average dh/dt= -2.5 m/yr 2003 2004 2005 2006 2007 2008 -5 5 0 dh(m)
19. Examples of dh/dt Computation: Petermann Glacier, Floating Tongue IGARSS July 2011, Vancouver, Canada
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21. Examples of dh/dt Computation: Petermann Glacier, Floating Tongue 500 m
22. Average Thickening/Thinning Rate, North Greenland IGARSS July 2011, Vancouver, Canada Extensive thinning at the onset of Petermann Gl. Thickening bulge at the onset of NE Ice Stream Tributary Recovering surge of Storstrommen Gl. m/yr Thickening bulge on Humboldt Gl.
23. Fusing ICESat Satellite and Airborne Topographic Mapper Airborne Laser Altimetry DATA for Change Detection in Greenland IGARSS July 2011, Vancouver, Canada Principles of operation, ATM conical scanner 400 m altitude 250 m swath width ATM laser scanning trajectories 1993-2009
24. Locations of SERAC solutions, red: ICESat; blue: ICESat/ATM SERAC solution, h(t) curve blue: ICESat, red:: ATM elevations Point ID: 11002118 RMS surface fitting error all laser points: 0.171 m Elevation: 1197 m Surface change rates are computed as derivatives of the fitted polynomial (red curve) Note the good agreement between airborne and spaceborne altimetry!
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26. IGARSS July 2011, Vancouver, Canada L2A 2003 Fall L3K 2008 Fall m/yr Greenland Ice Sheet thickening/thinning rates m/ m
27. Volume Change Rates from ICESat-ATM Observations, Sept 2003-Oct 2009 IGARSS July 2011, Vancouver, Canada (m/yr) Ice sheet mass balance from mass budget method (black) and GRACE (red), Rignot et al., 2011, GRL Average thickening/thinning rates Sept 2003 – Oct 2009 (L2A-L2F)
28. IGARSS July 2011, Vancouver, Canada N NW Jak SW NE E SE Volume change rates of major drainage basins
29. IGARSS July 2011, Vancouver, Canada L2A 2003 Fall L3K 2008 Fall m/yr Greenland Ice Sheet thickening/thinning rates m/ m
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32. NW sector, a closer look: Increasing thinning rates, propagating inland on Upernavik Glacier IGARSS July 2011, Vancouver, Canada (from Khan et al, submitted) Crossover C, 1197 m
There is a large uncertainty in the prediction of sea level rise as temperature increases – and probably the largest uncertainty is due to the uncertainty in predicting losses of ice sheets/glaciers due to ice dynamics, for example due to increase in sliding temperature and resulting calving…. Here are some predictions of sea level rise – note the uncertainties from 50 cm to almost 2 meters in the next 100 years.
A few words about he airborne altimetry. Sketch with aircraft shows the geometry of data acquisition, while the map of Greenland shows the location of point elevation measurements in Greenland.
