Open AccessVariations of ice bed coupling beneath and beyond ice streams: The force balance
Author(s) -
Hughes T.
Publication year - 2009
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2008jb005714
Subject(s) - ice stream , geology , ice divide , pressure ridge , ice sheet , sea ice growth processes , ice shelf , pancake ice , ice wedge , antarctic sea ice , geomorphology , streams , glaciology , arctic ice pack , mechanics , sea ice , cryosphere , geotechnical engineering , climatology , physics , oceanography , permafrost , hydrogeology , computer network , metamorphic petrology , computer science
A geometrical force balance that links stresses to ice bed coupling along a flow band of an ice sheet was developed in 1988 for longitudinal tension in ice streams and published 4 years later. It remains a work in progress. Now gravitational forces balanced by forces producing tensile, compressive, basal shear, and side shear stresses are all linked to ice bed coupling by the floating fraction ϕ of ice that produces the concave surface of ice streams. These lead inexorably to a simple formula showing how ϕ varies along these flow bands where surface and bed topography are known: ϕ = h O / h I with h O being ice thickness h I at x = 0 for x horizontal and positive upslope from grounded ice margins. This captures the basic fact in glaciology: the height of ice depends on how strongly ice couples to the bed. It shows how far a high convex ice sheet (ϕ = 0) has gone in collapsing into a low flat ice shelf (ϕ = 1). Here ϕ captures ice bed coupling under an ice stream and h O captures ice bed coupling beyond ice streams.