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Monday, 23 August 2010 14:29
Rocky

One of the most common descriptors of the penetration of sunlight in water is the diffuse attenuation coefficient, *K*(λ), or *K _{d}*(λ) when calculated from vertical profiles of downwelling irradiance,

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For homogeneous waters, a plot of the logarithm of *E _{d}*(λ,

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The equation defining *K _{d}* can also be written as

Ln[*E _{d}*(λ,

This is a linear equation of the form *Y=mx* where *m=K _{d}* is the slope.

When calculating *K _{d }*from vertical profiles of irradiance, irradiance values do not have to be calibrated as the irradiance units drop out.