Crustal deformation due to ice mass unloading at Jakobshavn Isbrae, Greenland, measured with ERS/Envisat/Radarsat SAR interferometry

American Geophysical Union, Fall Meeting 2008, abstract #G13B-0656

Crustal deformation due to ice mass unloading at Jakobshavn Isbrae, Greenland, measured with ERS/Envisat/Radarsat SAR interferometry

L. Liu, J. Wahr, I. Howat, A. S. Khan, M. Furuya, and I. Joughin

Abstract

Glaciers are among the most visible indicators of the effects of climate change. Jakobshavn Isbrae, the largest outlet glacier in Greenland, is observed to have been undergoing dramatic thinning and acceleration in speed in recent years. The changes in Jakobshavn Isbrae are likely important indicators of the dynamic response of the Greenland ice sheet to warming temperatures. And the rapid response may have a significant impact on the mass imbalance of the entire Greenland ice sheet. Using InSAR (Interferometric Synthetic Aperture Radar) processing, we study the crustal deformation near Jakobshavn Isbrae, with the goal of placing constraints on the ice mass loss of that glacier and the surrounding region. The biggest challenge of applying InSAR to this unloading problem is to distinguish the deformation signals, which are predominantly long-wavelength in the spatial domain, from the satellite orbit errors (or InSAR baseline errors). By stacking ERS and ENVISAT SAR interferograms, we can reduce the orbit errors and the atmospheric artifacts, since they both vary randomly in the time domain. For RADARSAT- 1 SAR data, whose orbit errors are significantly larger than the deformation signals, we estimate interferogram baselines empirically and study the short-wavelength components instead. Using the Lagrange Multiplier method, we incorporate several ground control points, including observations from one permanent GPS station (KAGA), into the baseline fitting in order to reconstruct some of the longer-wavelength components. We find good agreement between a variety of InSAR estimates of the secular deformation rates at different wavelengths and the corresponding deformation models based on independent ice elevation change measurements from NASA's Airborne Topographic Mapper (ATM).

Link to abstract: http://adsabs.harvard.edu/abs/2008AGUFM.G13B0656L