Fig. 4

Visualization of E1, E2, and peak SV. a Conceptualized E1, E2, and peak SV indices for a single acoustic reflection (modified from Penrose et al. 2005). The first echo appears at the bottom depth, and the second echo appears at double that depth. Peak SV is an index for the strongest reflections in the first echo. b The E1 and E2 layers and the position of peak SV in a part of a 200 kHz acoustic profile (based on the ReefMaster reference manual, ReefMaster Software Ltd.)