Physical Oceanography, Vol. 15, No. 3, 2005
CHARACTERISTICS OF UNDERWATER IRRADIATION IN THE BLACK SEA
IN SPRING (1993 AND 1995)
V. I. Man’kovskii and M. V. Solov’ev
We present the data on the values of the coefficients of vertical attenuation and diffusive reflec-
tion of light in the Black Sea in spring 1993 and 1995, compute the depths of one-percent quan-
tum irradiation and the parameter
specifying the fraction of attenuation of directed light as a
result of scattering:
and compare the characteristics of underwater irradiation in the
sea in different seasons for 1989–1995.
Since the second half of the 1980s, the hydrooptical characteristics of the Black Sea suffered significant
changes and, as a result, the transparency of water decreased as compared with its level typical of the preceding
period . This, in turn, affected the values of the coefficient of vertical attenuation of daylight (which became
much higher) and its spectral distribution (the minimum of attenuation of solar radiation shifted toward the regi-
on of long waves) . The indicated changes in the optical characteristics of waters were caused by changes in
the species composition of phytoplankton in the sea promoted by the influence of both anthropogenic and natural
ecological factors responsible for the mass growth of algae of the nanoplankton group .
In this connection, the problem of accumulation of data on the characteristics of the light field in the sea for
the current state of the marine ecosystem in different seasons seems to be quite urgent. For summer 1989 and
winter 1991, these data are presented in . In the present work, one can find the data on the characteristics of
underwater irradiation in spring 1993 and spring 1995.
Equipment and Procedure
The levels of underwater irradiation were measured with a photometer  at a wavelength of
responding to the minimum of the coefficient of vertical attenuation of daylight
in the currently existing
waters of the Black Sea . The measurements were carried out from the surface down to a depth of
fixed depths (multiples of
m). The coefficient of vertical attenuation of descending light is given by the for-
()↓ and E
()↓ are the levels of irradiation of the photometer from above at depths Z
The levels of irradiation from above E
()↓ and from below E
()↑ are used to find the coefficient of dif-
fusion reflection of daylight, namely,
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
44–48, May–June, 2005. Original article submitted November 4, 2003.
174 0928-5105/05/1503–0174 © 2005 Springer Science+Business Media, Inc.