Although the research priority of our cruise is magnetic data, we are not passing up any opportunity to use the state of the art sonar-based instruments on the Sikuliaq to conduct surveys of the ocean floor under our path. Because these instruments rely on the sending, receiving, and timing of sound waves through sea water, we must be sure to be able to account for all the factors which can affect the speed of sound in the water between the ship and the topography below.
Thanks to marine technician Ethan Roth for a great briefing on the XBT