Optical Characterization of Backscattering by Total Suspended Matter and Its Correlation with Phytoplankton Concentration in the Arabian Sea
This paper presents results of in-situ measured spectral characteristics of backscattering behavior for total particulate matter and its correlation with chlorophyll-a (Chl-a) concentration over open and coastal waters of Northeastern Arabian Sea. Bio-optical measurements were carried out during 1st–13th March 2009 in the coastal and open oceans of the Arabian Sea. Spectral slope of backscattering coefficient at 470 and 700 nm by particulate matter is estimated using Angstrom exponent. Average Angstrom exponent was found to be −1.25 for open ocean waters and for coastal waters −0.91. Chlorophyll-a concentration was estimated using blue green spectral ratio and maximum spectral ratio algorithm. Empirical maximum spectral ratio algorithm was found to be superior having r 2 = 0.99 and RMSE = 0.025. Estimated chlorophyll-a was then correlated with backscattering coefficient at 470 and 700 nm. A good correlation was found between backscattering coefficient at 700 nm and chlorophyll-a concentration having a coefficient of determination r 2 = 0.93 and RMSE = 0.06 for open ocean waters.
KeywordsSpectral Ratio Coloured Dissolve Organic Matter Total Suspend Matter Spectral Slope Total Particulate Matter
This work is supported under the Meteorology and Oceanography (MOP) II program of Indian Space Research Organization (ISRO). In this valuable advice and encouragement of Dr. Ajai, Group Director, MESG and Dr. J.S. Parihar, Deputy Director, RESA of Space Applications Center (ISRO), Ahmedabad is greatly acknowledged.
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