Remote imaging of internal solitons in the coastal ocean

During a combined in situ and airborne remote sensing exercise off Oceanside, CA, a Compact Airborne Spectrographic Imager (CASI) observed alongshore lineations, which were associated with an internal soliton packet accompanying a tidally generated internal solitary wave (solibore). The soliton packets were most evident in the images at green wavelengths, which penetrate the deepest into the water column, and only weakly evident at optical wavelengths with shallower penetration. We believe that this is the first observation of internal soliton packets determined from remotely sensed upwelled radiance. We hypothesize that the lineations were produced by changes in the upwelling radiance from the interior of the water column, not by changes in surface reflectance. Using a simulation, it is demonstrated that such lineations can be produced by vertical modulation of the inherent optical properties (IOPs) during the passage of the internal soliton packet. Since surface manifestations are not always present, this opens the potential for broadly based inventories of internal solitons in coastal waters.