HR: 08:00h
AN: C31C-01 INVITED     [Abstracts]
TI: Accumulation Variability and Wind-borne Snow Transport Across Lyddan Ice Rise, Antarctica
AU: * King, J C
EM: jcki@bas.ac.uk
AF: British Antarctic Survey, High Cross Madingley Road, Cambridge, CB3 0ET United Kingdom
AU: Anderson, P S
EM: psan@bas.ac.uk
AF: British Antarctic Survey, High Cross Madingley Road, Cambridge, CB3 0ET United Kingdom
AU: Vaughan, D G
EM: dgv@bas.ac.uk
AF: British Antarctic Survey, High Cross Madingley Road, Cambridge, CB3 0ET United Kingdom
AU: Mann, G W
EM: gmann@env.leeds.ac.uk
AF: School of Earth and Environment, University of Leeds, Leeds, LS2 9JT United Kingdom
AU: Mobbs, S D
EM: stephen@env.leeds.ac.uk
AF: School of Earth and Environment, University of Leeds, Leeds, LS2 9JT United Kingdom
AU: Vosper, S B
EM: simon.vosper@metoffice.com
AF: Met Office, FitzRoy Road, Exeter, EX1 3PB United Kingdom
AB: Redistribution of snow by the wind is the major contributor to spatial variability in snow accumulation over Antarctica on scales from metres to a few kilometres. Even small variations in wind speed associated with very gentle topography can give rise to large accumulation variations as a result of the highly nonlinear relationship between wind speed and snow transport. In this talk we examine the relationships between wind, topography and snow accumulation using observations made across an Antarctic ice rise. Lyddan Ice Rise is an approximately two-dimensional ridge, about 15 km wide, that rises 130m above the surrounding ice shelves. Surveys carried out using conventional stake measurements and ground penetrating radar reveal surprisingly large accumulation variations across this relatively gentle feature. On the scale of the ice rise itself, there is a gradual decline in accumulation moving from the ice shelf on the climatologically-upwind side to the climatologically downwind slope, where accumulation is reduced to around 65% of its upwind value. Superimposed on this broad-scale gradient are large (20-30%), localized variations in accumulation on a scale of around 1 km that appear to be associated with local variations in surface slope of around 0.01. The observed variations in accumulation agree well with calculations of snow redistribution made using wind measurements from automatic weather stations and winds derived from an airflow model, lending support to the hypothesis that snow redistribution is the major control on accumulation at this location. We discuss how our observations may relate to studies of accumulation variability in other parts of Antarctica, particularly the "megadune" fields of East Antarctica.
DE: 9310 Antarctica
DE: 3349 Polar meteorology
DE: 3307 Boundary layer processes
DE: 1827 Glaciology (1863)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting