Seismic Oceanography

My research uses the geophysical technique of seismic reflection imaging, to image thermohaline structures in the oceans. Seismic reflection imaging has been used to image the subsurface for almost a century, but the application to the water column was only considered in 2003.

Seismic reflection imaging works on the principle of sending acoustic energy downwards into the medium of interest, where a portion of this energy is then reflected back due to acoustic contrasts in the medium. In the oceans, these variations in acoustic properties are caused primarily by temperature contrasts, with differences as little as 0.03°C resolvable.

 

Reflections caused by temperature contrasts, detected using seismic reflection imaging.

The vertical resolution of the images produced is of order meters, which compared to conventional oceanographic methods (where the vertical resolution is commonly measured in millimeters) is very coarse, however the horizontal resolution of seismic oceanography is also of order meters, whilst the horizontal distance between sites in a conventional oceanographic survey is commonly tens of kilometers. By combining the two techniques of conventional and seismic oceanographic measurement therefore, there is exciting potential to improve our knowledge of thermohaline structures in the ocean, especially in the horizontal dimension.

My initial dataset comes from the North Atlantic, but I also have data from a cruise I was involved in to the Southern Ocean on the RV Melville, gathering data from the Agulhas Return Current. Both datasets benefit from coincident hydrographic measurements which allows direct correlation of what we see in the seismic data with that seen by conventional methods.


Last updated on 08-May-12 16:35