Finally some action!


Luan preparing for XBT deployment.
After a long, nine-day transit without much activity, we finally approached our survey site. By the time I started my shift at 2:00 am on May 2nd, we had already begun collecting bathymetric data from the multibeam echosounders. It was nice to record a bathymetric structure that is about 1000 m high and 7000 m across. For us watchers, such a feature is always more interesting than looking at a flat seabed for hours during a shift. Most excitingly, at 7:25 am we deployed the first OBS into the water. Right afterward, I got a chance to personally deploy a XBT into the water. This is to record the temperature and salinity of the seawater and help constrain the water density which in turn controls the velocity of sound waves in water. We need this information on a regular basis to calibrate the seafloor depth recorded by the multibeam. I The XBT was supposed to sink to 1.6 km depth and then to be retrieved for its reading. Anyway, we have 30 OBSes that need to be deployed every 15 km. So it will take the next couple of days to finish the first OBS profile. Then we can start with the airguns. We will also be learning how to do ray-tracing modeling with the OBS data. Our days are now packed with very exciting scientific activities!

Luan Nguyen
Rice
Deployment of the first OBS!

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