Extinction Coefficient calculations 

Rough calculation using secci disc: 
k = 1.45 / d 
where; 
k = extinction coefficient 
d = depth at which secchi disc is still visible to
naked eye 


May also be expressed as; 
k = (2.3 x (log I_{d1} log I_{d2}))
/ (d2  d1) 
where; 
k = extinction coefficient 
I_{d1}= Intensity of light (of a specific
wavelength) at depth "d1" 
I_{d2}= Intensity of light (of a specific
wavelength) at depth "d2" 
