Ocean acoustic-tomography (OAT) inversion depends on relative clock offsets, transducer positions, the sound-speed profile, and the system time offset, which are unknown and coupled. We propose a segmented Bayesian method for their unified calibration. Reciprocal travel-time half-differences are used in a linear inversion of relative clock offsets, whereas half-sums are used in a nonlinear joint inversion of transducer positions, a low-order modal sound-speed profile, and the system time offset, with posterior uncertainties quantified. Under the applicability conditions, the joint posterior factorizes by the two parameter groups, supporting separate two-stage estimation. Field data from a shallow-water test site show that, within the principal 4–14 m ray-sampling range, the posterior profile reduces the root-mean-square error (RMSE) against an independent measured profile by approximately 41% (at the adopted data weighting) relative to the prior, mainly by correcting depth-mean sound speed. In temporal extrapolation, parameters calibrated over the first 40 h predict one-way travel times over the following 11 h; prediction residuals and systematic bias are substantially reduced. Ratios of post-calibration residual RMSE to short-term channel variability are 0.87–1.70, indicating residuals remain of the same order as intrinsic channel variability. The method calibrates OAT system parameters and improves prediction for data excluded from the inversion.

Acoustic scattering by vortices is a fundamental problem in studies of wake scattering from underwater moving targets. To investigate dual-vortex scattering in low-Mach-number underwater wakes, this study constructs a two-dimensional equal-strength Taylor vortex-pair model and employs the convected wave equation to examine acoustic-wave scattering in an idealized dual-vortex flow field. The rotational configuration, incidence angle, and dimensionless parameter kL are taken as key control variables. The results show that, under low-kL conditions, the co-rotating vortex pair exhibits stronger overall equivalent-scatterer characteristics, with higher scattering energy and weaker sensitivity to the incidence angle. In contrast, the counter-rotating vortex pair is more sensitive to the incidence angle, and its scattering cross section varies in an approximately U-shaped manner, reflecting more pronounced interference characteristics. As kL increases, the mean scattering cross section follows an approximate (kL)4 power-law growth, and the scattered energy gradually concentrates in the forward direction. The mean scattering cross sections of the co-rotating and counter-rotating vortex pairs gradually converge, although differences remain in the mainlobe position, interference structure, and directional distribution. Interference-field analysis indicates that vortex-pair scattering is not a simple linear superposition of two single-vortex scattered fields. Instead, inter-vortex coupling modifies the local scattered field through rescattering and phase interactions, and this modification varies with the incidence angle and vortex spacing. These results reveal scattering-field interactions within the smallest multi-vortex unit and are of significant importance for analyzing multi-vortex acoustic scattering in the wake fields of underwater targets, as well as for vortex detection and identification.