Geoacoustic inversion of fine-grained sediments via vertical reactive intensity from distributed explosive sources

Normalized vertical reactive intensity (Qzn⋆), computed from coherent combinations of complex pressure and vertical velocity measured from a vector acoustic sensor, preserves the local interference dynamics of dispersed modes at the receiver independent of source location or propagation distance. Measurements of impulsive sources deployed during the 2022 Seabed Characterization Experiment recorded by vector acoustic sensors at three locations are used for sediment classification and geoacoustic inversion. In addition to classifying thick vs thin mud, inversion results from the thickest portion of the New England Mud Patch suggest that in May 2022 the mud sound speed at the top of the sediment is faster at 1472 [1464, 1480] m  s-1 (brackets indicate 95% confidence bounds) and the gradient is smaller at 3.46 [1.03, 5.59] s-1 than inversion results from the same location in March 2017, consistent with the observed changes in oceanography. Inversions of data collected on and off the mud patch are also consistent with previously observed east-west increase in surficial mud sound speed.