## 3 Results and Discussion
### Contrasting Examples of Light Field Characteristics and AOPs
At shorter wavelengths within the approximate range 580-650 nm that was away from significant effect of chlorophyll-\(a\) fluorescence, Raman scattering appeared to exert a dominant influence on \(R\) throughout much of the examined water column. Owing to this inelastic process a shoulder-like feature was seen in the \(R\) spectra around 600 nm at intermediate measurement depths (16-49 m), which developed into a distinct maximum with further increase of depth to 67 m (Figure 5d). This pattern is consistent with an increasing role of Raman scattering with depth [37; 69; 70; 73]. These results also suggest that the effects of Raman scattering were more easily detectable or distinguishable from the effects of chlorophyll-\(a\) fluorescence in the data of AOPs than in the irradiance data. Figure 6 shows the attenuation coefficients for the four irradiances, specifically \(K_{d}\), \(K_{u}\), \(K_{ol}\), and \(K_{ou}\), as derived from the measurements of irradiance quartet, \(E_{d}\), \(E_{u}\), \(E_{ad}\), and \(E_{ou}\), respectively. Similar to other AOPs discussed above, the \(K\)-coefficients were less variable in the blue-green than in the red portion of the spectrum, both in terms of the spectral shape (Figure 6a-d) and vertical profiles (Figure 6e-h). One of the most remarkable features was that the \(K\)-coefficients in the red (more specifically for \(\lambda>580\)-600 nm) were generally smaller than the pure water absorption coefficient, \(a_{w}\). This feature resulted from inelastic processes and was more pronounced for \(K_{u}\) and \(K_{ou}\) than \(K_{d}\) and \(K_{od}\). In the chlorophyll-\(a\) fluorescence band, \(K_{d}\) and \(K_{od}\) approached zero in the upper portion of the \(Chl_{max}\) layer (Figure 6e,f), which is consistent with an earlier observation that \(E_{d}\) and \(E_{od}\) are nearly constant within that layer (Figure 4e,g). A stronger effect within the 683 nm band was observed for the \(K_{u}\) and \(K_{ou}\) coefficients that assume negative values in the upper portion of the \(Chl_{max}\) layer (Figure 6g,h). This is again consistent with the measurements of \(E_{u}\) and \(E_{ou}\) which both increased with depth within that layer (Figure 4f,h). Similar increase of \(E_{u}\) in the red band (685 nm) with depth within the \(Chl_{max}\) layer was previously observed by [PERSON] and [PERSON] [37]. The presence of negative values for the attenuation of upwelling irradiance was also demonstrated through RT simulations of light field within highly scattering near-surface layer of bubble clouds entrained by wave breaking [91]. Other interesting features of the long-wavelength portion of \(K\)-spectra include a maximum at 683 nm below \(z_{Chlmax}\) (for all \(K\)-coefficients, see Figure 6a-d) or a maximum that could peak at wavelengths longer than about 600 nm but shorter than 683 nm at depths above \(z_{Chlmax}\) (especially for \(K_{d}\) and \(K_{od}\), see Figure 6a,b). These features arise from differential spectral effects of inelastic processes as a function of increasing wavelength. It is also interesting to note that a distinct feature at these intermediate depths was observed in the spectra of \(\overline{\mu}_{d}\) and \(\overline{\mu}\) (Figure 5b,d). This can be explained by higher attenuation coefficient leading to more light concentrated around the vertical direction. In contrast to the red portion of the spectrum, in the blue-green spectral region where the effects of inelastic processes are much weaker, the \(K\)-coefficients were higher than \(a_{w}(\lambda)\). At these wavelengths, especially at 440 nm, the vertical profiles of \(K\)-coefficients exhibited maximum values within the \(Chl_{max}\) layer, and hence generally resembled the shape of \(Chl(z)\) profile. It is also noteworthy that the \(K\)-coefficients at all different wavelengths became nearly identical at the greatest depth of about 60 m used in these determinations (Figure 6e-h).