Journal Article

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

Fastook, James, Hughes, Terence, Sargent, Aitbala

2011

Overview

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. Key Points The height of ice above the bed is determined mainly by ice‐bed coupling Uncoupling occurs mainly along ice streams which discharge up to 90% of ice Because of #1 and #2 ice sheets can rapidly self‐destruct

• Publisher: Blackwell Publishing Ltd
• Subject: Antarctica / Byrd Glacier / Byrd Glacier, Antarctica / Cryosphere / Drainage systems / Geophysics / Glaciers / Glaciohydrology / High performance computing / Ice shelves / ice streams / Ice thickness / ice-bed coupling / Lakes / Laminar flow / Stream discharge / Stream flow / Streams