Sensitivity Analysis of Group Velocity Dispersion for the Sediment-Borne Mode in the Deep Ocean

This paper presents the effects of environmental parameters on the group velocity dispersion for the sediment-borne mode. A three-layer, fluid, and range-independent model is considered. The synthetic signal corresponding to sediment-borne mode is simulated using modal theory, and its group velocity dispersion behaviors are summarized in the time-frequency (TF) domain. The environmental parameters include near-surface water sound speed profile (SSP), water depth, and some bottom parameters. The first-order modal group velocity dispersion in the frequency range of 10-300 Hz is used for the sensitivity analysis. Results of the sensitivity study show that the sediment sound speed and sediment thickness are the main parameters influencing the group velocity dispersion. The basement sound speed, sediment density, and basement density have comparable and much fewer effects. The near-surface water SSP, which is greatly affected by seasonal and diurnal changes, and the water depth, are almost insensitive parameters to the group velocity dispersion. The above results may become the fundamental basis for geoacoustic inversion.