We know that reflectance is influenced both by solar angle and satellite viewing angle, namely BRDF effects (Bidirectional Reflectance Distribution Function). But few researchers conducted BRDF corrections for water quality remote sensing during model devlelopment and intercomparison between two sensors. Whether or not this issue should be considered? How much accuracy can be improved for water quality estimation if BRDF was corrected?
I've done a lot of BRDF work related to vegetation in the past. I'm just starting a project that looks at water dynamics. The main directional issue I've seen over water is specular reflection, which is usually negligible for vegetation. It was an issue when we worked with POLDER data over northern Canada where a ~7km pixel is often a mixture of toundra and small water bodies. Wind will change the reflectance too, but I'm not sure if there is an obvious directionality of that effect.
Sylvain G Leblanc Thanks for your reply. You give a unique perspective on this issue. Maybe that is why remote sensing reflectance (unit: 1/sr), which has been removed the effects of specular reflection by reasonable viewing geometry for ground based observation, is used as model input for estimating water quality parameters.
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