Abstract
Abstract. Ground-based radio echo sounding data acquired along the 1700 km US-ITASE traverse have been used to determine ice attenuation and relative basal reflectivity across the major catchments funneling ice from East Antarctica to the Ross Ice Shelf. We find that basal reflectivity varies locally by up to 40 dB which we interpret as due to changes in the phase state at the bed. Some, though not all, areas of high local reflectivity are observed to have flat-lying bed reflections indicative of sub-glacial lakes. We compare basal reflectivity to ice balance velocity and find a general association of higher flow speeds with high radar reflection strength. This set of observations from two independent remotely sensed geophysical data sets extends the range of field observations to the interior of East Antarctica and confirms the importance of basal lubrication on modulating the ice dynamics of the largest ice sheet on the planet.
Highlights
The discovery of numerous lakes beneath the Antarctic Ice Sheets (e.g. Siegert et al, 2000) and the observation that in some cases lakes drain and refill on annual to sub-annual time scales (e.g. Smith et al, 2009; Carter et al, 2009; Fricker et al, 2007; Wingham et al, 2006) indicates that a pervasive sub-glacial hydrological network extends beneath large swathes of the ice in Antarctica
We have acquired 1700 km of ground-based radio echo sounding data along the 2006–2008 US-ITASE traverse from Taylor Dome to South Pole (Mayewski et al, 2003)
Surface ice velocities were derived from a combination of tandem phase ERS-1 interferometric SAR (InSAR) and longer repeat ERS-1 (35 day) and RADARSAT (24 day) InSAR and speckle tracking data sets produced by several different groups at the University of Washington, Jet Propulsion Laboratory and Ohio State University (Edwards, 2009)
Summary
The discovery of numerous lakes beneath the Antarctic Ice Sheets (e.g. Siegert et al, 2000) and the observation that in some cases lakes drain and refill on annual to sub-annual time scales (e.g. Smith et al, 2009; Carter et al, 2009; Fricker et al, 2007; Wingham et al, 2006) indicates that a pervasive sub-glacial hydrological network extends beneath large swathes of the ice in Antarctica. The discovery of numerous lakes beneath the Antarctic Ice Sheets (e.g. Siegert et al, 2000) and the observation that in some cases lakes drain and refill on annual to sub-annual time scales Smith et al, 2009; Carter et al, 2009; Fricker et al, 2007; Wingham et al, 2006) indicates that a pervasive sub-glacial hydrological network extends beneath large swathes of the ice in Antarctica. Basal melting, supporting till deformation of West Antarctic ice streams, is responsible for ∼ 90% or more of the velocity (Blankenship et al, 2001). In East Antarctica, where a pervasive, thick layer of deformable sediment is less likely, the role of subglacial
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