HR: 0830h
AN: C11C-0840    [PDF]
TI: Persistent Patterns of Windborne Snow Re-distribution on an Antarctic Ice Rise: Implications for the Equilibrium Profile and Flow
AU: * Vaughan, D G
EM: d.vaughan@bas.ac.uk
AF: British Antarctic Survey, Madingley Road, Cambridge, CB3 0ET United Kingdom
AU: Anderson, P S
EM:
AF: British Antarctic Survey, Madingley Road, Cambridge, CB3 0ET United Kingdom
AU: King, J C
EM:
AF: British Antarctic Survey, Madingley Road, Cambridge, CB3 0ET United Kingdom
AU: Mann, G W
EM:
AF: School of Geography, Leeds University, Leeds, LS2 9JT United Kingdom
AU: Mobbs, S D
EM:
AF: School of Geography, Leeds University, Leeds, LS2 9JT United Kingdom
AU: Ladkin, R
EM:
AF: British Antarctic Survey, Madingley Road, Cambridge, CB3 0ET United Kingdom
AU: Arthern, R
EM:
AF: British Antarctic Survey, Madingley Road, Cambridge, CB3 0ET United Kingdom
AB: We show that layers observed using ground-penetrating radar over Lyddan Ice Rise, Antarctica are approximate isochrones. We use these layers to map persistent spatial ($<$1 km) variations in snow accumulation over the ice rise, and the pattern of ice flow around the summit region. We find that the ice-flow divide, which has remained static for several decades, is currently around 1 km away from the ice rise summit. The layers also show that major spatial variability in snow accumulation ($>$50% of the mean) is directly related to extremely subtle changes in surface slope ($<$1%), and that this spatial variability has been stable for several decades. This finding implies that, in addition the normal control on the equilibrium profile of the ice rise, i.e. the relationship between surface slope versus ice-flow, the equilibrium profile is also by the relationship between surface slope and accumulation rate. We investigate the interaction of these two effects using a 2-dimensional isothermal time-dependent ice sheet model. We find that in this case, the surface slope / accumulation rate relation is sufficiently weak, that in this case, a time-stable equilibrium profile does exist, and that such a relationship does not necessarily imply result in surface waves or dunes. However, the interaction between surface slope and accumulation does significantly modify the profile of the ice rise and displaces the position of the summit by around ~1 km. We conclude that the position of the summit of Lyddan and similar ice rises and ice caps, is highly dependent on the local wind climatology and could be significantly affected by a change in the wind climatology. Such effects of wind modification of ice rise profiles may have particular importance for the interpretation of ice cores collected from ice rises and ice caps.
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
DE: 4540 Ice mechanics and air/sea/ice exchange processes
SC: Cryosphere [C]
MN: 2003 Fall Meeting