Physical Oceanography, Vol.
MATHEMATICAL MODELING OF MARINE SYSTEMS
MODELING OF THE BLACK-SEA ECOSYSTEM
V. L. Dorofeev
and G. K. Korotaev
We study the seasonal variability of the Black-Sea ecosystem by using a three-dimensional phys-
ical-biogeochemical model. Its physical part is a model of circulation in the Black Sea with high
spatial resolution capable of the description of both large-scale circulation in the basin and meso-
scale eddies. The ecological module of the model is based on a version of the already applied
one-dimensional model generalized to the three-dimensional case and includes two components
of phytoplankton, two groups of zooplankton of different sizes, bacteria, dissolved and sus-
pended organic substances, jointly described nitrates and nitrites, and ammonium. The applica-
tion of the eddy-resolving model as the basic model of circulation in the Black Sea enable us to
qualitatively reproduce the processes of vertical entrainment of deep-sea waters rich in biogenic
elements into the upper layer and transfrontal transport of the coastal waters into the open part of
the sea. Our numerical experiments also demonstrate that this model realistically reproduces the
seasonal dynamics of the distribution of phytoplankton in the Black Sea. In addition, the model
reproduces the space structure of the biogeochemical variables of state correlated with the meso-
scale features of circulation.
Under the conditions of restricted possibilities of organization of continuous and multifactor observations of
the biogeochemical processes and continuous monitoring of the dynamics of the sea, a potentially important role
is played by the models of the Black-Sea ecosystem. The numerical models of the ecosystem combined with a
model of dynamics of the sea must guarantee the possibility of interpolation and extrapolation of the data of reg-
ular satellite observations of the sea color and fragmentary biogeochemical contact observations in space and
time and continuous reproduction of the collections of variables whose direct measurement is impossible. How-
ever, the construction of a mathematical model capable of giving an adequate quantitative description of decadal
variations of the Black-Sea ecosystem is an extremely difficult problem. For the last
ecosystem suffered noticeable transformations caused by the climatic changes and anthropogenic influence.
Therefore, a model used for the continuous monitoring of the ecosystem must correctly reproduce diverse and
complex interactions between various species or groups of species playing different roles in all stages of the evo-
lution of the ecosystem.
The experiments aimed at modeling the Black-Sea ecosystem were originated relatively long ago.
scription can be found in the works by Vinogradov et al. [1, 2] and Belyaev et al. [3, 4]. Models of various types
are also presented in [5, 6]. The models of ecosystems are, as a rule, based on the nitrogen cycle. Therefore, all
variables are expressed via the equivalent concentration of nitrogen and the equations used to describe the evolu-
tion of the ecosystem reflect the balance of nitrogen in its transitions between different forms. However, in re-
cent years, the greatest successes were attained in [7–10]. These investigations were based on a one-dimensional
model of the ecosystem reproducing the vertical distributions of the fields and taking into account five different
Institute of Marine Sciences of the Near-East Technical University, Erdemli, Turkey.
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
59–72, January–February, 2007. Original article submitted September 1,
2005; revision submitted October 7, 2005.
0928-5105/07/1701–0053 © 2007 Springer Science+Business Media, Inc. 53