Seismic oceanography. Correlation between seismic images and oceanographic data of thewater column structure

Abstract

Multichannel seismic (MCS) imaging is becoming a new tool for oceanographic research (Holbrook et al, 2003). These new oceanographic images provide snapshots of the water column reflectivity with horizontal resolution about three orders better than typical oceanographic data (10 m versus 10 km), so they are potentially very helpful for oceanographers to investigate the internal structure of the water and the causes of the reflectivity. With this general aim, simultaneous MCS and oceanographic data were acquired in June 2006 in the Gulf of Cadiz with R/V Hespérides, in the framework of the Euromargins- SWIM oceanographic survey. 12 Expandable Bathythermograph (XBT) probes were dropped while shooting along a 50 km seismic profile, with the purpose of directly comparing obtained seismic images and temperature data. MCS data were acquired using a 1050 cu. in. source and a 2400 m, 96 channels streamer. Other oceanographic variables, such as salinity (Machín and Pelegrí, 2007), velocity (Chen and Millero, 1977), temperature, velocity and salinity gradients, and Turner angles (Ruddick, 1983) were calculated based on XBT data and plotted on top of seismic images. [...]