Sea surface multispectral index model for estimating chlorophyll a concentration of productive coastal waters in Thailand

Abstract

Chlorophyll a (Chl a) concentration in water can be estimated using remote sensing methodology. This study uses Chl a high absorption and high reflectance wavelengths to produce indices stable for Chl a monitoring. The relationships between the indices and Chl a are determined and then applied to satellite bands for model development. The sea surface spectrum was measured in situ using a portable spectrometer, and Chl a concentration was analyzed in the laboratory. Satellite images were obtained from Landsat-5 for the day of sampling. The results of a three-band index from the spectrometer composed of wavelengths 435, 488, and 692 nm indicate the most significant correlation with Chl a concentration. The exponential relation was observed with the highest correlation coefficient of r2= 0.83. The index model was applied to Landsat-5 data, and the observed Chl a dataset was compared with that estimated from Landsat-5. This analysis gave a high correlation of r2= 0.73. © 2009 CASI.