A Model for Variations of Sound Speed and Attenuation from Seabed Gas Emissions

The release of greenhouse gas, such as carbon dioxide (CO
₂
) and methane (CH
₄
) into the atmosphere, is a major source of global warming. As such a large emphasis has been placed on developing methods of measuring the amount of gas escaping from natural seep sites, particularly in the marine environment. Fortunately, gaseous bubbles crossing the seabed interface into the water column are relatively easily detected and quantified by passive acoustics. Here we design an active acoustic model to determine the frequency dependent changes in sound speed and attenuation in the water column due to gaseous CO
₂
. Our approach is to formulate a numerical model simulating the propagation of sound energy at different frequencies through a mixed media incorporating a gas bubble plume with detection on a hydrophone.