In the east, the offshore and onshore branches of the loop tend to cross mainly between the 5 m depth contour and the shoreline (Figure 5). There is some uncertainty regarding the location of their crossings with respect to the true local depth due to the insufficient accuracy of the bottom topography model, sea level instability, and inadequate spatial resolution of radiance data in the near-shore space. In any case, the latter comprises the surf zone. Its radiance peaks during onshore winds when the bottom reflectance radiance is added to the radiance of the water column enhanced by the backscattering of particles resuspended by wave-breaking. The surf zone is virtually free of wave-breaking during

offshore winds and, therefore, the dominance of the onshore radiance PD0332991 solubility dmso over the offshore one in the close vicinity of the shoreline is a quite predictable event. The contribution of bottom reflection to the red radiance vanishes at depths Z > 3 m, whereas green radiance can be contributed to by bottom reflection in much deeper waters ( (1) and Figure 1). These considerations agree well with the fact that maximum Lmaxwnav(λ) gravitated to the eastern shores

of the testing area regardless of wind direction ( Figure 3) and that the maxima of profiles dLav (670) tend to be shifted shorewards as compared to similar maxima at shorter wavelengths ( Figure 5). The largest positive differences dLof_onwnav in the blue, green and red occurred at depths 10 < Z < 15 m ((d)–(f) in Figure 5). The spectral-different dLof_onwnav LY2157299 changed concurrently in the zonal direction and occupied one and the same profile segments, where the bottom depth is large enough to prevent the wave-breaking GPX6 resuspension mechanism. Hence, the difference in sediment resuspension, induced by opposing winds, has to be the only cause of the dLof_onwnav (670) peak. Evidently, the same is true for dLof_onwnav (555) and dLof_onwnav (443), although these radiances can be enhanced by the background wind-independent backscattering and by bottom reflection at 10 < Z < 15 m at the water transparencies typical of the southern Caspian Sea. The background component vanishes when passing from the offshore

and onshore radiances to their difference. Most probably, the same is true as regards the bottom reflection: to our knowledge, non-sinusoidal sand ripples are the only conceivable factor in the directional dependence of bottom reflectance, but we failed to find any evidence of such ripples in the study area. Hence, specific features of resuspension mechanisms for offshore and onshore winds determine the occurrence of the radiance loops and peaks of dLof_onwnav (λ) at sites with more than 10 m of water. The resuspension mechanisms in shallows are closely associated with cross-shelf water transport, which has been subjected to intensive field experimental studies in the last 10 years (Lentz, 2001, Lentz and Chapman, 2004 and Kirincich et al.