The spectral values of the pure water volume scattering coefficient bow (l) recommended in Vol. I, Chapter 2 (Sect. 2.4) are those of Morel (1974), as reported by Smith and Baker (1981). Following Van Zee et al. (2002), however, we recommend here that preference be given to the scales of Buiteveld, et al. (1994). Both scales are listed in Table 1.1 for comparison. The difference between the two scales is £ 0.0001 m^-1 at wavelengths > 475 nm, increases to £ 0.0005 m^-1 as wavelength decreases to 400 nm, and increases further to £ 0.0014 m^-1 at 340 nm. In no instance does the difference closely approach the 0.005 m^-1 measurement uncertainty of beam attenuation and absorption meters that are commercially available to date.

Refer to Table 1.1 for the Volume absorption and scattering coefficients for pure water. (pdf)

The angular distribution of the molecular scattering phase function _w (y), as approximated with equation (2.29) (Vol. I, Ch. 2), is illustrated in Figure 1.2.  The magnitude of _w (y)  represents the probability that a photon scattering interaction with a water molecule will redirect the photon path direction by an angle y  measured from its original path. The shape of _w (y)  is sometimes referred to as “isotropic” in the literature, a characterization that is true only in that the function is axially symmetric and the probabilities of forward and backward scattering are equal.

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More on IOPs: absorption • beam attenuation • volume scattering function • fluorescence • turbidity • scattering
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