Furthermore, radiance being reflected and scattered by suspended sediment or phytoplankton may not reach the sensor as a result of further scatter or absorption by the in-water constituents, and attenuation by the water itself. Hence it is not truly possible to assume a linear relationship between spectral response and water composition. Attempts have been made to model the effect that stratification of constituents has on water-leaving radiance. This takes into consideration that material near the surface is more important to the spectral response of the ocean than that at greater depths. The weighting results in an algorithm which sums phytoplankton with depth.
Variation also occurs within coastal waters over time.
For this reason on-going studies have adopted seasonal as well as local algorithms. Future Developments Overcoming the problems caused by local and seasonal variability may be possible with more detailed models of radiative transfer. Sathyendranath et al. The approach was reasonably successful and is was found to be much faster than 'true' inverse modelling of radiative transfer. At present there are too many variables and uncertainties in both the ocean and atmosphere systems in the coastal zone for this analytic approach to provide very accurate results.