GEOPHYSICAL RESEARCH LETTERS, VOL. 38, L10504, 6 PP., 2011
doi:10.1029/2011GL047109
doi:10.1029/2011GL047109
Antarctic grounding line mapping from differential satellite radar interferometry
Key Points
- Prior mapping techniques yield large uncertainties
- Antarctic coastline completely redefined along nearly all its outlet glaciers
- Underlines critical need for direct mapping of ice sheet grounding lines
Department of Earth System Science, University of California, Irvine, California, USA
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
Department of Earth System Science, University of California, Irvine, California, USA
Department of Earth System Science, University of California, Irvine, California, USA
Abstract
The delineation of an ice sheet grounding line, i.e., the transition boundary where ice detaches from the bed and becomes afloat in the ocean, is critical to ice sheet mass budget calculations, numerical modeling of ice sheet dynamics, ice-ocean interactions, oceanic tides, and subglacial environments. Here, we present 15 years of comprehensive, high-resolution mapping of grounding lines in Antarctica using differential satellite synthetic-aperture radar interferometry (DInSAR) data from the Earth Remote Sensing Satellites 1–2 (ERS-1/2), RADARSAT-1 and 2, and the Advanced Land Observing System (ALOS) PALSAR for years 1994 to 2009. DInSAR directly measures the vertical motion of floating ice shelves in response to tidal oceanic forcing with millimeter precision, at a sample spacing better than 50 m, simultaneously over areas several 100 km wide; in contrast with earlier methods that detect abrupt changes in surface slope in satellite visible imagery or altimetry data. On stagnant and slow-moving areas, we find that breaks in surface slope are reliable indicators of grounding lines; but on most fast-moving glaciers and ice streams, our DInSAR results reveal that prior mappings have positioning errors ranging from a few km to over 100 km. A better agreement is found with ICESat's data, also based on measurements of vertical motion, but with a detection noise one order of magnitude larger than with DInSAR. Overall, the DInSAR mapping of Antarctic grounding lines completely redefines the coastline of Antarctica.
Received 15 February 2011; accepted 6 April 2011; published 26 May 2011.
Citation: (2011), Antarctic grounding line mapping from differential satellite radar interferometry, Geophys. Res. Lett., 38, L10504, doi:10.1029/2011GL047109.
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