Acoustic observations of the ocean interior: Stories of gas bubbles

Gas bubbles are ubiquitous in the ocean and play an important role in several ocean processes. Gas bubbles formed by breaking wind waves play a role in the transfer of gas and momentum across the air-sea boundary. Methane gas formed by both biogenic and thermogenic processes is transported via bubbles into the water column and sometimes to the atmosphere. Gas bubbles also provide a mechanical advantage to several marine organisms including siphonophores and fishes with swim bladders. The large impedance contrast between the gas inside of the bubble and the surrounding water makes them easy to observe using acoustic wavesâ€"especially when the acoustic system operates near a bubble’s resonance frequency. In this talk I will describe the use of multibeam, split-beam, and broadband echo sounders for detecting gas bubbles in the ocean and, once having detected them, for understanding their story (i.e., their evolution and ultimate fate).

Speaker: Tom Weber, Univ. of New Hampshire