Use of water Raman emission to correct airborne laser fluorosensor data for effects of water optical attenuation

Abstract

Airborne laser fluorosensor measurements of fluorophore concentrations in surface waters are highly sensitive to interference from changes in optical attenuation. This interference can be eliminated by normalizing the fluorescence signal with the concurrent water Raman signal. In our application to remotely monitor chlorophyll a concentrations in fresh waters, the Raman-corrected chlorophyll a fluorescence measurements were found to be highly correlated with chlorophyll a ground truth data. Also, the reciprocal of the water Raman signal was seen to vary directly as the beam attenuation coefficient. It is suggested that this latter relationship be exploited as a means for remotely sensing changes in the optical attenuation of surface waters.