Physical Oceanography, Vol. 18, No. 2, 2008
EFFECT OF FINELY DIVIDED ADMIXTURES ON THE SCATTERING
OF LIGHT IN “PURE” FILTERED WATER
E. B. Shybanov
We consider the problem of disagreement between the theoretical and experimental values of the
spectral volume scattering function of “pure” filtered water. To explain this disagreement, we
advance a hypothesis of existence of two-dimensional space correlations between the locations of
a finely divided suspension in the liquid. We deduce analytic relations for the scattering of light
in the approximation of statistically equilibrium distribution of particles over the surfaces of
spheres randomly arranged in the medium. The experimental data on the volume scattering
function of “pure” filtered water (the sizes of particles do not exceed
are analyzed. The
results of numerical analysis according to the model of spherical surface distribution of finely di-
vided particles in water are in qualitative agreement with the spectral volume scattering function
of filtered water.
The angular scattering coefficient of water β
) defined as the energy scattered in a given direction by
a unit volume of the liquid is an important hydrooptical parameter specifying the characteristics of propagation
of light in water media. The main aim of interpretation of the data of measurements of light fields in the sea and
water-leaving radiance is to establish the relationships between the spectral characteristics of scattering and mi-
crophysical parameters of the medium, such as the relative refraction index of suspended particles and the func-
tion of size distribution of particles. Seawater is, as a rule, characterized by a great variety of suspended sub-
stances, including mineral particles (sand, clay, and lime and silicon remains of plankton), particles of biological
origin (detritus and phytoplankton cells), and air bubbles. Despite the difference between the quantitative and
qualitative compositions of these particles, the plots of measured scattering coefficients on the logarithmic scale
are almost similar. In the classification of the experimental phase functions of light scattering, these curves can
be regarded as belonging to the class of indicatrices of scattering on optically “soft” particles, i.e., on particles
whose relative refraction index is close to one. The characteristic features of the experimental and theoretical
(based on the model of optically “soft” particles) scattering indicatrices can be described as follows:
(i) the presence of a strong forward peak of scattering near
(ii) smooth monotonic behavior of the volume scattering function in the rear half sphere
(iii) small values of the probability of backscattering.
It is clear that the procedure of formal determination of the microphysical properties of scattering according
to the phase function of scattering would reveal the presence of large particles whose relative refraction index is
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol, Ukraine.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
46–56, March–April, 2008. Original article submitted September 19,
2006; revision submitted October 19, 2006.
86 0928-5105/08/1802–0086 © 2008 Springer Science+Business Media, Inc.