CHARACTERISTICS OF THE LIGHT-FIELD IN HIGHLY TURBID WATERS - A MONTE-CARLO STUDY

The nature of the light field in waters with very high ratios of scattering coefficient to absorption coefficient (b: a) has been explored by Monte Carlo modeling. The progressive change in the angular structure of the field at a specified optical depth (z(m)) as b: a increases up to an extreme value of 200 is illustrated in terms of the changes in average cosines mu(d)BAR[z(m)], mu(u)BAR[z(m)], muBAR[z(m)] and irradiance reflectance (R[z(m)]). The dependence of the vertical attenuation coefficient for downward irradiance on absorption and scattering is satisfactorily represented by K(d)(z(m)) = (a2 + 0.245ab)1/2. A nomogram is presented, with the help of which the values of the absorption and scattering coefficients for highly turbid water bodies can be estimated from underwater irradiance data.