HR: 0800h
AN: OS21C-1263    [Abstracts]
TI: Seismic Imaging of the Antarctic Circumpolar Current near Drake Passage
AU: Koenitz, D
EM: koenitz@esc.cam.ac.uk
AF: University of Cambridge, Bullard Laboratories Madingley Road, Cambridge, CB3 0EZ United Kingdom
AU: * White, N
EM: nwhite@esc.cam.ac.uk
AF: University of Cambridge, Bullard Laboratories Madingley Road, Cambridge, CB3 0EZ United Kingdom
AU: Singh, S
EM: singh@ipg-jussieu.fr
AF: Institut du Physique de Globe, 4 Place Jussieu, Paris, 75005 France
AU: England, R
EM: rwe5@le.ac.uk
AF: University of Leicester, Department of Geology University Road, Leicester, LE1 7RH
AU: Hobbs, R
EM: r.w.hobbs@durham.ac.uk
AF: University of Durham, Department of Earth Sciences Science Laboratories, Durham, DH1 3LE United Kingdom
AB: Inspired by the recent work of Steven Holbrook and colleagues, we have reprocessed a set of legacy seismic reflection profiles in order to image features associated with thermohaline circulation. As a starting point, we selected academic and industrial datasets from a region which encompasses the Falkland Plateau just east of the Drake Passage which is an important choke point for deep-water circulation. These datasets cross the Sub-Antarctic and Polar Fronts associated with the Antarctic Circumpolar Current and associated water masses. As expected, careful velocity picking during processing considerably improved the acoustic images. Unfortunately the upper 400 milliseconds is contaminated by the bubble pulse of the airgun source. This bubble pulse also contributes to the general `ringiness' of the images. In the Argentine Abyssal Plain, the intrusion of North Atlantic Deep Water into Lower Circumpolar Deep Water is spectacularly observed. Toward the base of this intrusion, a mesoscale eddy is visible. In the Falkland Trough, just south of the Falkland Islands, seasonal variations of the thermohaline circulation can be deduced from a set of profiles which were shot at different times. In the Scotia Sea, the Polar Front is clearly visible, separating acoustically stratified waters to the south from acoustically blank waters to the north. We have used WOCE and other legacy hydrographic datasets to corroborate our results.
DE: 7299 General or miscellaneous
DE: 4200 OCEANOGRAPHY: GENERAL
DE: 4259 Ocean acoustics
DE: 4520 Eddies and mesoscale processes
DE: 4532 General circulation
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting