Spectral variation of ba) and wb) for the four different macro-regions: head (red), neck (green), body (blue), and bottom (orange). The derived spectra from the global analysis are reported in black. The absorption common to all the spectra in the 0.8–1 μm is likely a residual calibration artifact. Some abrupt oscillations of w and b at certain wavelengths are due to degeneration in the fitting.