Stochastic formalism-based seafloor feature discrimination using multifractality of time-dependent acoustic backscatter

Abstract. Dual-frequency echo-envelope data acquired using the normal-incidence single-beam echosounder system (SBES) have been examined to study its scale invariant properties. The scaling and multifractality of the SBES echo envelopes (at 33 and 210 kHz) were validated by applying a stochastic-based multifractal analysis technique. The analyses carried out substantiate the hierarchy of multiplicative cascade dynamics in the echo envelopes, demonstrating a first-order multifractal phase transition. The resulting scale invariant parameters (α, C₁, and H) establish gainful information that can facilitate distinctive delineation of the sediment provinces in the central part of the western continental shelf of India. The universal multifractal parameters among the coarse and fine sediments exhibit subtle difference in α and H, whereas the codimension parameter C₁ representing the sparseness of the data varies. The C₁ values are well clustered at both the acoustic frequencies, demarcating the coarse and fine sediment provinces. Statistically significant correlations are noticeable between the computed C₁ values and the ground truth sediment information. The variations in the multifractal parameters and their behavior with respect to the ground truth sediment information are in good corroboration with the previously estimated sediment geoacoustic inversion results obtained at the same locations.