Physical Oceanography, Vol.
5, January, 2012 (Ukrainian Original No.
5, September–October, 2011)
EXPERIMENTAL AND FIELD RESEARCH
SPECTRAL CONTRIBUTIONS OF THE COMPONENTS OF SEAWATER TO
THE BEAM ATTENUATION COEFFICIENT IN SURFACE WATERS OF
THE MEDITERRANEAN SEA
V. I. Man’kovsky
We compute model spectra of the beam attenuation coefficient in surface waters of the Mediterranean
Sea. These spectra are used to determine the contribution of the components of seawater (suspended
matter, yellow substance, pigments of phytoplankton, and pure water) to the beam attenuation coeffi-
cient in different types of seawater. For the surface waters, we establish the relationship between the
light scattering coefficient and the attenuation coefficient at a wavelength of 547 nm and determine the
background (limiting minimum) value of the coefficient of absorption by the yellow substance in waters
of the Mediterranean Sea. It is compared with the values of the same parameter for some other basins
(Black Sea, Lake Baikal, Baltic Sea, and oceanic waters).
Keywords: beam attenuation coefficient, suspended matter, chlorophyll, yellow substance.
In the process of optical monitoring of marine basins, it is customary to use the results of measurements of
the beam attenuation coefficient. The beam attenuation coefficient (BAC) is an integral optical characteristic
equal to the sum of the coefficients of absorption and scattering of light by the substances suspended and dis-
solved in water.
For the ecological monitoring of basins, it is quite important to be able to realize the inverse transformation
of the BAC in order to get information about the substances contained in water and their spectral contributions
to this coefficient. Modeling proves to be an efficient method for the solution of inverse problems of this sort.
In , the numerical analyses of the contributions of various components of seawater to the BAC were car-
ried out on the basis of the spectral physical model of attenuation of light. These analyses were based on the
experimental data on the scattering coefficients at a wavelength of 550 nm for angles of 1 and 45° and the spec-
tral absorption of light by water.
A semiempirical approach based on the spectral physical model  was used for this purpose in [2, 3] with
application of additional empirical relations between some optical characteristics. In modeling, we use the ex-
perimentally measured spectral distribution of BAC. The criterion of adequacy of the applied semiempirical
approach is its agreement with the experimental data. In the present work, we also apply a model of this kind.
To compute model spectra, we use the experimental spectra of BAC measured in the Mediterranean Sea in
May 1998 in the course of the expedition of the Marine Hydrophysical Institute of the Ukrainian National Acad-
Marine Hydrophysical Institute, Ukrainian National Academy of Sciences, Sevastopol, Ukraine.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
14–29, September–October, 2011. Original article submitted April 2, 2010;
revision submitted June 15, 2010.
0928–5105/12/2105–0305 © 2012 Springer Science+Business Media, Inc. 305