Ice-bed coupling beneath and beyond ice streams: Byrd Glacier, Antarctica

Abstract

[1] Ice sheet thickness is determined mainly by the strength of ice-bed coupling that controls holistic transitions from slow sheet flow to fast streamflow to buttressing shelf flow. Byrd Glacier has the largest ice drainage system in Antarctica and is the fastest ice stream entering Ross Ice Shelf. In 2004 two large subglacial lakes at the head of Byrd Glacier suddenly drained and increased the terminal ice velocity of Byrd Glacier from 820 m yr −1 to 900 m yr −1 . This resulted in partial ice-bed recoupling above the lakes and partial decoupling along Byrd Glacier. An attempt to quantify this behavior is made using flowband and flowline models in which the controlling variable for ice height above the bed is the floating fraction of ice along the flowband and flowline. Changes in before and after drainage are obtained from available data, but more reliable data in the map plane are required before Byrd Glacier can be modeled adequately. A holistic sliding velocity is derived that depends on , with contributions from ice shearing over coupled beds and ice stretching over uncoupled beds, as is done in state-of-the-art sliding theories.

Glaciation in the Late Noachian Icy Highlands: Ice accumulation, distribution, flow rates, basal melting, and top-down melting rates and patterns

“…In this case, narrow regions of "fast" flow, with velocities exceeding 100 mm/yr, are observed near the margin and concentrated in low topographic areas. These "ice streams" (Hughes, 1977;Raymond, 2000;Schoof, 2002;Hughes et al, 2011) are even more pronounced in the 15X and 20X cases (Figs. 11 and 12d, h, l), with velocities of 500 to well over 1000 mm/yr.…”

Potential groundwater and heterogeneous heat source contributions to ice sheet dynamics in critical submarine basins of East Antarctica

“…The specifics of ice sheet dynamics depend on many factors including, but not limited to, solar radiation, precipitation, climate, ocean influences, and bed topography and geology. While surface measurements are easier to obtain compared to the subsurface measurements, the subsurface factors are of great importance to the overall ice sheet's stability [e.g., Blankenship et al, 1986Blankenship et al, , 1993Blankenship et al, , 2001Lowe and Anderson, 2003;Hughes et al, 2011;Thoma et al, 2012;Schroeder et al, 2014]. While a few continental ice sheet models incorporate limited subglacial data and estimations of bed geometry, homogeneous geothermal heat flux, and interfacial water systems (e.g., PISM) [Winkelmann et al [2011], others elements such as groundwater flow, sediment erosion, heterogeneous geothermal heat flux, and poroelastic sediments are rarely incorporated [e.g., Flowers et al, 2005;Pattyn, 2010].…”

Basal buoyancy and fast moving glaciers: in defense of analytic force balance

“…In a long series of papers, T. Hughes presents the geometric approach to the balance of forces acting on ice shelves, ice streams, and interior ice (Hughes, 1986(Hughes, , 1992(Hughes, , 1998(Hughes, , 2003(Hughes, , 2009a(Hughes, , b, 2012Hughes et al, 2011Hughes et al, , 2016. Rather than working his way through the basic equations, as done by most other investigators, including Van der Veen and and Van der Veen (2013), he presents deriva-tions based on graphical interpretation of triangles representing forces acting on an ice column.…”