Water quality remote sensing in the visible spectrum
The development of water quality retrieval algorithms is discussed in terms of causal dependence of the upwelling spectral radiance upon the water composition. Unlike clear marine/oceanic waters, for which linear regression retrieval relationships are valid, inland and coastal zone water masses with a high degree of optical complexity necessitate the development of more subtle retrieval approaches. At the basis of such approaches are models considering the conjoint optical impact of several co-existing aquatic components on the water leaving radiance spectral distribution. Such a model for Lake Ladoga is described. Monte Carlo simulations have been performed to analyse the spectral and angular variations of the upwelling radiance scattered by the water column into the atmosphere. Optimal conditions for conducting water quality remote sensing in case of natural waters of various optical complexity are explored and relevant recommendations are formulated.