Contribution of Raman Scattering in Remote Sensing Retrieval of Suspended Sediment Concentration by Empirical Modeling

In this paper, the author investigates the effect of Raman scattering on remotely sensed suspended sediment concentration (SSC) through the analysis of various SSC retrieval models in the coastal waters (Case 2) of the Bay of Bengal. A higher Raman contribution is observed in waters containing less SSC and chlorophyll-a concentration. Tassan´s model, which used three wavelengths, i.e., 490, 555, and 670 nm, is able to account for Raman contribution at three emission wavelengths. The analysis showed the highest ~14% fraction in the computed SSC and 8.4% fraction in the reflectance (at 555 nm) due to Raman scattering. A fraction of ~14% in the SSC due to Raman scattering is significant and should be addressed in SSC retrieval models. More channels (wavelengths) are required to adequately account for the Raman contribution for estimating SSC from the remote sensing reflectance. The inclusion of blue and infrared wavelengths in the empirical models of SSC retrieval is suggested as a topic of future research, because the excitation and emission do occur at these respective wavelengths.