Reflection from the Bottom
Spectral transmittance for 10 m in various water types.
WHAT CAN BE DETECTED, MEASURED, AND MAPPED IN WATER?
• Material floating on the water surface is usually easy to detect and to map its areal extent.
• Certain things cannot be detected.
• This includes gasses (oxygen, carbon dioxide) dissolved in water, inorganic salts (sodium chloride), and acidity (pH).
Algae, for example, appears prominently in near infrared as a bright surface on a dark background.
Floating oil is detectable, though not so prominently, in shorter wavelengths, 350–450 nm, and again in the thermal infrared.