At a depth of 5m. the water column effectively removes light from the upwelling signal at wavelengths longer than 600 nm, and greatly attenuates the upwelling signal at wavelengths shorter than 400 nm. Rayleigh scattering by the atmosphere increases the radiance at the shorter wavelengths, but does not detract from our ability to discriminate between scenes.
To determine the best wavlength regions for discriminating between living coral and coralline algae with a satellite instrument, we examined the percentage difference between the top-of-atmosphere radiances over coralline algae and Montastraea cavernosa, as a function of wavelength and depth in the water column. If a suitable signal-to-noise ratio can be obtained in a satellite instrument operating with 10-meter pixel, resolution, it should be possible to distinguish between coral species.