Seismic Oceanography

A secondary goal of our work, co-funded by the NSF-PO program, was to conduct seismic oceanography -- that is, to image the internal fine-structure of the ocean using reflection seismology. We deployed 50 XBT's that measured ocean temperature, for comparison to our reflection data. To do the deployments, Captain Landow and Sci. Officer Ted Koczynski devised XBT "flumes" on the port and starboard sides, consisting of long PVC pipes angled downward from the paravane deck and supported by either the OBS deck crane or a vane boom. Here's a picture of the starboard XBT flume:

Although we were somewhat disappointed with the relatively monotonous temperature structure of this part of the Caribbean, we were quite surprised (and pleased) to see very clear reflections from even tiny temperature fluctuations, as the figures below describe.

We believe these results will redefine the sensitivity of seismic reflection data in imaging ocean fine-structure. Certainly the powerful, broadband, well-tuned 36-gun array of the Langseth appears to be an ideal source for seismic oceanography.

On the Pacific side, where we expect a much more "interesting" ocean, we will deploy about 180 XBT's, 11 XCTD's, and 25 XCP (expendable current profilers) during our seismic work there. Stay tuned for more.

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