Extended Data Fig. 2: Acoustic profiles decomposition in a function basis system.

Example of averaged day and night profiles from a 4×4 degrees cell (a) decomposed in two function basis systems (b, c). 18 basis functions were fitted to the mean profiles at 40 m depth intervals, from 20 to 750 m depth (red-blue lines). Function coefficients were used to describe the day and night shape profiles at each location (d). Functional PCA and clustering was performed on the coefficients matrix to classify the acoustic seascape. Dots and horizontal bars in acoustic profiles indicate the median and the interquartile range, as Volume backscattering strength (Sv, dB re 1 m⁻¹).