Contribution of Raman scattering to water-leaving radiance: a reexamination

We have reexamined the contribution of Raman scattering to the water-leavin g radiance in case 1 waters by carrying out radiative transfer simulations that combine the latest reported measurements of the absorption coefficient of pure water with direct measurements of the spectral variation of the Ra man-scattering coefficient. The resulting contribution of Raman scattering is then compared with experimental measurements of the water-leaving radian ce, and the fractional contribution of radiance produced by Raman scatterin g to the total radiance measured at a given wavelength is determined. The r esults show that (1) the contribution of Raman scattering to the water-leav ing radiance in an ocean of pure seawater is as much as 50-100% larger than earlier predictions, and (2) the Raman contribution does not decay as rapi dly with increasing concentrations of chlorophyllouslike pigments C as pred icted earlier. In fact, the Raman fraction for C less than or similar to 1 mg/m(3) is approximately greater than or similar to 8% at wavelengths of in terest in ocean color remote sensing and therefore cannot be ignored in oce an color modeling. (C) 1999 Optical Society of America.