Remote estimation of chlorophyll concentration in polluted marine waters in Haifa Bay, Southeastern Mediterranean

Chlorophyll distribution in Haifa Bay was estimated in a period of very high chlorophyll concentrations (up to 70 mg/m ³) using remotely sensed data. Radiometric measurements with spectral resolution of 2 nm in the range from 400 to 850 nm, were taken simultaneously with samples for chlorophyll concentration, turbidity and Secchi disk transparency. Prominent features of the reflectance spectra were a wide minimum from 420 to 500 nm, a maximum at 550-570 nm, a minimum at 676 nm and a maximum reflectance showed near 700 nm. High spectral resolution data were used for the selection of the most suitable spectral bands for remote estimating of chlorophyll concentration. The magnitude and position of the peak near 700 nm were highly correlated with chlorophyll concentration. The reflectance height at 690 nm above the baseline from 670 to 850 nm and area above the baseline were used as sensitive indicators of chlorophyll concentration. The best model enabled estimation of chlorophyll concentration with an error of less than 4.3 mg/m ³. For the purpose of chlorophyll mapping in Haifa Bay, the use of three relatively narrow spectral bands was sufficient. Radiometric data were also used to simulate radiances in the channels of TM Landsat and to find the algorithm for chlorophyll assessment. The ratios TM3/TM1 and (TM2-TM3)/TM1 were used and enable chlorophyll estimation with an error of less than 8 mg/m ³.