HR: 15:10h
AN: OS32C-07    [PDF]
TI: Time-Lapse Seismic-Reflection Images Of Thermohaline Intrusions in an Oceanographic Front
AU: * Pearse, S
EM: pearse@uwyo.edu
AF: Department of Geology and Geophysics, University of Wyoming, P.O. Box 3006, Laramie, WY 82071 United States
AU: Holbrook, W S
EM: steveh@uwyo.edu
AF: Department of Geology and Geophysics, University of Wyoming, P.O. Box 3006, Laramie, WY 82071 United States
AU: Paramo, P
EM: paramo@uwyo.edu
AF: Department of Geology and Geophysics, University of Wyoming, P.O. Box 3006, Laramie, WY 82071 United States
AU: Schmitt, R W
EM: rschmitt@whoi.edu
AF: Woods Hole Oceanographic Institution, MS 21, Woods Hole, MA 02543 United States
AB: Recent results show that thermohaline intrusions can be acoustically imaged using conventional seismic reflection profiling methods. During acquisition of the data presented by Holbrook et al (2003) across the Labrador and North Atlantic currents, repeat profiles were also recorded. Here, we present pairs of images of thermohaline intrusions in an oceanographic front with a temporal separation in the order of days. Although distinct water masses and their internal structure are visible, they change dynamically such that the level to which similar structures can be recognised between the images varies substantially. The magnitudes of these changes both include and far exceed those expected for internal waves. Tentative estimates of the apparent rate at which these comparable structures have changed include vertical motions of 4.6 x 10$^{-3}$ m/s and lateral motions of 69 x 10$^{-3}$ m/s, while the oceanographic front is remarkably stable with little vertical or lateral movement. The apparent motion on 2-dimensional cross-sections may at least in part be due to lateral variations of 3-dimensional structures. Our results show that repeat seismic-reflection profiling is an effective means of studying the dynamic nature of fine-scale thermohaline structure in the ocean.
DE: 4500 OCEANOGRAPHY: PHYSICAL
SC: Ocean Sciences [OS]
MN: 2003 Fall Meeting