Use of dual methods to infer methane bubble populations in gassy sediment: Inversion of propagation data

The inversion of the acoustic properties of gassy sediments presents the optimum manner of determining the in situ distribution of sediment‐based methane bubbles. An in situ device that measures both compressional wave attenuations and combination‐frequency components in gassy sediment lying within 2 m of the seabed has been developed at the University of Southampton. This device was deployed at an inter‐tidal site along the South coast of England. Compressional wave attenuations were measured from 10 to 100 kHz though the analysis of propagation signals transmitted from a variety of sources to a buried co‐linear hydrophone array, with propagation distances spanning 0.5 to 2 m. Measured attenuations were inverted to infer in situ bubble size distributions using both established and new acoustic models for gassy sediment. The analysis and results of the combination‐frequency component are described in a companion paper.