Mapping microphytobenthos in the intertidal zone of Northern ...
Mapping microphytobenthos in the intertidal zone of Northern ...
Mapping microphytobenthos in the intertidal zone of Northern ...
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Figure 4. Inversion <strong>of</strong> data from <strong>the</strong> Bay <strong>of</strong> Somme May<br />
2002 campaign: a – simple band ratio; b – normalized<br />
ratio; c – scaled band area.<br />
Each technique was <strong>the</strong>n validated us<strong>in</strong>g a newly acquired data set <strong>in</strong> Baie de Somme (May 30, 2002). Chl a<br />
concentration was estimated by <strong>in</strong>vert<strong>in</strong>g <strong>the</strong> result<strong>in</strong>g functions and compared to <strong>the</strong> concentrations measured from<br />
<strong>the</strong> samples. As shown on Figure 4, <strong>the</strong>re is a strong correlation (R 2 > 0.9) between estimated and measured Chl a<br />
concentration, no matter which algorithm is used, for <strong>the</strong> range <strong>of</strong> Chl a concentrations encountered that day (50 –<br />
200 mg.m -2 ). More measurements under different conditions are still needed to crosscheck <strong>the</strong>se results.<br />
3.2. Airborne data<br />
In a first step, field reflectance spectra were convolved to airborne sensor bandpasses. New regressions were<br />
derived for <strong>the</strong> three approaches. Then a ratio image was produced as well as, after cont<strong>in</strong>uum removal, normalized<br />
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