title: The distribution of basal water between Antarctic subglacial lakes from radar sounding.
abstract: Antarctica's subglacial lakes have two end member geophysical expressions: as hydraulically flat, radar reflective regions highlighted in ice surface topography and radar sounding profiles ('definite lakes'), and as localized sites of elevation change identified from repeat elevation observations ('active lakes') that are often found in fast flowing ice streams or enhanced ice flow tributaries. While 'definite lakes' can be identified readily by high bed reflectivity in radar sounding, the identification and characterization of less distinct subglacial lakes and water systems with radar sounding are complicated by variable radio-wave attenuation in the overlying ice. When relying on repeat elevation observations, the relatively short times series and biased distribution of elevation observations, along with the episodic nature of 'active lake' outflow and replenishment, limit our understanding of how water flows under the ice sheet. Using recently developed methods for quantifying the radar scattering behaviour of the basal interface of the ice, we can avoid the problem of attenuation, and observe the plumbing of the subglacial landscape. In West Antarctica's Ross Sea Embayment, we confirm that extensive distributed water systems underlie these ice streams. Distributed water sheets are upstream in the onset regions of fast flow, while canal systems underly downstream regions of fast flow. In East Antarctica, we use specularity analysis to recover substantial hydraulic connectivity extending beyond previous knowledge, connecting the lakes already delineated by traditional radar sounding or surface elevation transients.
authors.affiliation: Institute for Geophysics, University of Texas at Austin, Austin, TX, USA duncan@ig.utexas.edu.
authors.forename: D A
authors.identifier: http://orcid.org/0000-0002-6866-8176
authors.initials: DA
authors.lastname: Young
authors.affiliation: Institute for Geophysics, University of Texas at Austin, Austin, TX, USA.
authors.forename: D M
authors.identifier: http://orcid.org/0000-0003-1916-3929
authors.initials: DM
authors.lastname: Schroeder
authors.affiliation: Institute for Geophysics, University of Texas at Austin, Austin, TX, USA.
authors.forename: D D
authors.initials: DD
authors.lastname: Blankenship
authors.affiliation: Institute for Geophysics, University of Texas at Austin, Austin, TX, USA.
authors.forename: Scott D
authors.initials: SD
authors.lastname: Kempf
authors.affiliation: Institute for Geophysics, University of Texas at Austin, Austin, TX, USA.
authors.forename: E
authors.identifier: http://orcid.org/0000-0001-7485-543X
authors.initials: E
authors.lastname: Quartini
keywords: Antarctica geophysics; glaciology; remote sensing