Sheet, stream, and shelf flow as progressive ice-bed uncoupling: Byrd Glacier, Antarctica and Jakobshavn Isbrae, Greenland
- 1School of Earth and Climate Sciences, Climate Change Institute, University of Maine, Orono, ME, USA
- 2School of Science and Humanities, Husson University, Bangor, ME, USA
- 3Computer Sciences Department, Climate Change Institute University of Maine, Orono, ME, USA
- 4Center for Remote Sensing of Ice Sheets, School of Engineering, University of Kansas, Lawrence, KS, USA
Abstract. The first-order control of ice thickness and height above sea level is linked to the decreasing strength of ice-bed coupling along flowlines from an interior ice divide to the calving front of an ice shelf. Uncoupling progresses as a frozen bed progressively thaws for sheet flow, as a thawed bed is progressively drowned for stream flow, and as lateral and/or local grounding vanish for shelf flow. This can reduce ice thicknesses by 90 % and ice elevations by 99 % along flowlines. Original work presented here includes (1) replacing flow and sliding laws for sheet flow with upper and lower yield stresses for creep in cold overlying ice and basal ice sliding over deforming till, respectively, (2) replacing integrating the Navier–Stokes equations for stream flow with geometrical solutions to the force balance, and (3) including resistance to shelf flow caused by lateral confinement in a fjord and local grounding at ice rumples and ice rises. A comparison is made between our approach and two approaches based on continuum mechanics. Applications are made to Byrd Glacier in Antarctica and Jakobshavn Isbrae in Greenland.