HR: 11:55h
AN: C12B-07    [Abstracts]
TI: A 44 kyr Paleo-Roughness Record From Antarctica
AU: Barnes, P R
EM: piers.barnes@csiro.au
AF: Univ Florence, Dept Chem Analyt Chem, Sesto Fiorentino,, Florence, I-50019 Italy
AU: Barnes, P R
EM: piers.barnes@csiro.au
AF: Univ New South Wales, School of Material Science and Engineering, Kensington, Sydney, NSW 2052 Australia
AU: * Wolff, E W
EM: ewwo@bas.ac.uk
AF: British Antarctic Survey, Madingley Road, Cambridge, CB3 0ET United Kingdom
AU: Mulvaney, R
EM: rmu@bas.ac.uk
AF: British Antarctic Survey, Madingley Road, Cambridge, CB3 0ET United Kingdom
AB: Two 788 m high resolution conductivity records from ice cores drilled at Dome C, Antarctica, provide an unprecedented opportunity to examine the past roughness of the ice sheet surface. We measured the distribution of the depth differences between matched synchronous events in the cores. This enabled the mean surface height distribution to be estimated for time intervals in the past. The technique was confirmed by checking the results against the conductivity profile of a third nearby core (120m depth), enabling uncertainties to be established. The mean standard deviation of surface roughness was 0.029 m for 0 to 11.5 kyr BP and 0.031 m for 18 to 45 kyr BP in ice equivalence. A record of this nature allows us to assess the reliability of the fine scale data in an ice core record. Specifically how well the preserved information represents the mean conditions at the time of deposition and the extent to which short term events may be missing from the core. This is of particular interest when matching volcanic horizons with other paleo records and when studying rates of volcanism. We find the probability of a typical volcanic signal being indistinguishable from background noise is ~ 6% during the Holocene but ~ 26% during the last glacial period. The 44 kyr roughness record, originating from dunes and sastrugi at the ice sheet surface, is likely to be a function of past wind speed, accumulation rate and temperature. Future developments constraining this relationship should allow conclusions regarding past local wind speed to be drawn from the record.
DE: 8409 Atmospheric effects (0370)
DE: 9310 Antarctica
DE: 3344 Paleoclimatology
DE: 1863 Snow and ice (1827)
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting