Estimating Geostrophic Shear from Seismic Images of Oceanic Structure

Sheen, Katy L.; White, Nicky; Caulfield, Colm P.; Hobbs, Richard W.

Abstract

It is shown that geostrophic vertical shear estimates can be recovered from seismic (i.e., acoustic) images of thermohaline structure. In the Southern Ocean, the Antarctic Circumpolar Current forms a loop within the Falkland Trough before it flows northward into the Argentine Basin. Seismic profiles that cross this loop show the detailed structure of different water masses with a horizontal resolution of O(10 m). Coherent seismic reflections are tilted in response to current flow around the Falkland Trough. Average slopes were measured on length scales that are large enough to ensure that the geostrophic approximation is valid (i.e., with a Rossby number <0.1). By combining shear estimates with satellite altimetric measurements and acoustic Doppler current profiles, geostrophic velocities can be calculated throughout the data volume. This technique for estimating geostrophic vertical shear from legacy seismic images yields useful information about the spatial and temporal variation of mesoscale circulation.

Citation

Sheen, K. L., White, N., Caulfield, C. P., & Hobbs, R. W. (2011). Estimating Geostrophic Shear from Seismic Images of Oceanic Structure. Journal of Atmospheric and Oceanic Technology, 28(9), 1149-1154. https://doi.org/10.1175/jtech-d-10-05012.1

• Journal Article Type: Article
• Online Publication Date: Sep 1, 2011
• Publication Date: Sep 1, 2011
• Deposit Date: Jan 16, 2012
• Publicly Available Date: Feb 17, 2017
• Journal: Journal of Atmospheric and Oceanic Technology
• Print ISSN: 0739-0572
• Electronic ISSN: 1520-0426
• Publisher: American Meteorological Society
• Peer Reviewed: Peer Reviewed
• Volume: 28
• Issue: 9
• Pages: 1149-1154
• DOI: https://doi.org/10.1175/jtech-d-10-05012.1