Ocean chlorophyll retrieval algorithms

The fact that the presence of chlorophyll influences the optical properties which otherwise called as change in the ocean color, makes us to use the sensor that can detect the ocean color for chlorophyll evaluation. It was recognised that colorimetric estimates of chlorophyll could be most difficult in coastal waters where the interferences by yellow substances and suspended sediments would be considerable. Nevertheless in nearshore and offshore waters the colorimetric estimates of chlorophyll from the radiance data is possible. A comparison of chlorophyll retrieval algorithms is made and their applicability is evaluated. Except in specific areas like mouths of estuaries, coastal zones influenced by river runoff etc. the empirical models can help to estimate total phytoplankton pigments from ratios formed from the upwelling radiances at 440, 520, 550 and 670 nanometers. From these results it is clear that our ability to relate pigment characteristics is limited by the less quantity of good quality bio-optical data on which any model can be developed and implemented.