2013 Volume 40 Issue 3 Pages 149-156
In studies of mass and heat transfers in the ocean, it is very important to determine the seafloor hydrothermal flows in mid-oceanic ridges. However, whole images of such hydrothermal flows and their internal structures are not easily captured or evaluated, and there is no established method for doing so. Here we report our development of a method for observing and delineating seafloor hydrothermal flows with an acoustic method. The proposed observation system consists of an acoustic video camera named “DIDSON,” a concentrator lens (1°), and a pan-and-tilt mechanism. DIDSON is an acoustic lens-based sonar that can substitute for an optical system in turbid or dark water where optical systems fail. The pan-and-tilt mechanism rotates the DIDSON with its concentrator lens to scan the hydrothermal flows discharging from the seafloor. We conducted a tank experiment to evaluate the utility of the proposed system for seafloor hydrothermal activity observation. We found that the system was able to delineate the image of an artificial seafloor hydrothermal flow; that is, a heated water flow that was pumped into the experimental tank through a narrow silicon tube. This result indicated that the proposed system will be of practical use.
