Fig. 4

Synthetic test results assuming the double-triangular array geometry. Kinematic array positioning results of the synthetic data assuming the double-triangular array geometry (Fig. 2b) are shown: a, g east–west component of array positions, b, h north–south component of array positions, c, i vertical component of array positions, d, j NTD, e, k east–west component of underwater delay gradient, and f, l north–west component of underwater delay gradient. a–f Positioning results assuming a laterally stratified sound speed structure; g–l positioning results assuming a horizontally graded sound speed structure. Green diamonds show the results estimated by conventional array positioning solving the vertical component assuming a horizontally graded sound speed structure, and other symbols shown are the same as in Fig. 3