Solar stimulated inelastic light scattering in clear sea water

Solar Fraunhofer lines are used as indicators of the inelastic light scattering in the sea water. Data from both inshore and off-shore are presented and compared with results of theoretical modeling. Very good agreement is found between the modeled and measured proportion of inelastic to elastically scattered and direct light at 589nm when the Raman scattering coefficient of Marshall and Smith(1) (1990) (0.00026m(-1)) is used, as opposed to that of Slusher and Derr(2) (1975) (0.00078m(-1)). At 656nm tile agreement is not as good, indicating possible interference from other sources such as Chlorophyll fluorescence. Recent work has extended the measurements to include smaller absorption lines, such as 689nm, where significant filling has been measured at the surface due to the Chlorophyll fluorescence. This technique allows the natural fluorescence to be measured, even at the surface where there is still a significant amount of direct solar light.