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Malaysian Tiungsat-1 Imagery for Water Quality Mapping
For a case involving two water quality components, i.e. chlorophyll, C, and suspended sediment, P, the simultaneous equations for the two channels given by Gallie and Murtha (1992) can be expressed as
where bbw(i) = backscattering coefficient bbc*= chlorophyll coefficient bbp = sediment coefficient aw(i)= absorption coefficient ac*= chlorophyll specific absorption coefficient ap*= sediment specific absorption coefficient C= chlorophyll P= suspended sediment 4. Regression Algorithm TSS concentration can be obtained by solving the two simultaneous equations to obtain the series of terms R1 and R2 that is given as P = ao+a1R1+a2R2+a3R1R2+ a4R12+ a5R22+ a6R12R2+ a7R1 2R22+a8R12R22+… (3) Where aj, j = 0, 1, 2, … are the coefficient for equation (3) that can be solved empirically using multiple regression analysis. This equation can also be extended to the three-band method given as P = eo+e1R1+e2R2+e3R3+ e4R1R2+ e5R1R3+ e6R2R3+ e7R12+e8R22+e9R32 (4) where the coefficient ej, j = 0, 1, 2, … can also be solved empirically. 5. Data Analysis and Result A Tiungsat-1 satellite scene of the study area contained 1024 x 1024 pixels. The image contained band-to-band registration error and also systematic banding. In this study, the three-band images were shifted accordingly so that the three bands overlap each other. An image size of 420 x 429 pixels was then extracted covering the study area. Table 1 shows the parameters of the Tiungsat-1 scene and Table 2 shows the Tiungsat-1 sensor characteristics for bands 1 to 3. The spatial resolution of the image pixel is 78 m (Astronautic Technology, 2002). Table 1. Scene parameters of Tiungsat-1 used in this study
Table 2. Tiungsat-1 sensor characteristics for band 1 to 3
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