Physical Oceanography, Vol.
5, January, 2012 (Ukrainian Original No.
5, September–October, 2011)
NUMERICAL MODEL OF THE SUBMARINE FRESH-WATER DISCHARGE
IN A KARST CAVITY
N. B. Shapiro
We discuss the results of numerical experiments aimed at the reconstruction the structure of hydrophysi-
cal fields in a karst cavity (in the region of Cape Aiya on the South Coast of Crimea) observed in the
course of the second specialized expedition in September 2008. To describe the process of submarine
fresh-water discharge, we use a three-dimensional hydrostatic model with a priori specified boundaries
of the layers (
levels) in the “rigid-lid” approximation including the procedure of “convec-
tive adjustment.” It is shown that only a good vertical resolution enables one to give a quantitatively cor-
rect description of a thin upper freshened layer of the sea. It is shown that, in order to get an adequate
picture of the influence of bottom topography on the upper layer of the sea, it is reasonable to use a
mixed grid along the vertical combining the
coordinates. We also present the results of nu-
merical experiments allowing us to estimate the effects of location, number, and power of fresh-water
sources placed on the lateral boundary of the cavity.
Keywords: numerical modeling, hydrostatic model, submarine fresh-water discharge, karst cavity.
The present work continues our investigations devoted to the numerical simulation of the process of subma-
rine discharge in a karst cavity located in the region of Cape Aiya on the South Coast of Crimea. The results of
numerical simulations can be found in [1, 2]. Note that, in , we present and discuss the data of observations
obtained in the course of two special expeditions, whereas the analysis of the situation observed in the course of
the first expedition in September 2007 is made in .
In the present work, one can find the results of numerical experiments aimed at the reconstruction of the
structure of hydrological fields in the same karst cavity observed in the course of the second expedition in Sep-
tember 2008 (i.e., in one year after the first expedition). In the subsurface layer, we also clearly detected the
presence of freshened waters with a minimum level of salinity of 10‰, i.e., lower than in 2007 by 2‰. In the
abyssal layers, the level of salinity was equal 18.2‰, as in 2007. In the upper layer of sea, the water tempera-
ture was equal to 22.3–23.3°C, increased with the depth, and reached 24.3°C. On the whole, the water tempera-
ture was much higher than in 2007, when it varied from 14.7–15°C on the sea surface to 14.2°C at the bottom
due to a wind-induced recession.
The structure of currents in the cavity was qualitatively identical to the picture observed in the first expedi-
tion, namely, in a thin upper layer with a thickness of ~
0.2 m, the water flowed out of the cavity (with a veloc-
ity of ~ 4 cm/sec), whereas in deeper levels, the flow of water was directed into the cavity.
On the basis of the data on the current velocity and salinity in the section (corresponding to the entry to the
cavity) and the conditions of stationary balance of mass and salt, we estimated the total output
of the sources
of fresh water discharging in the cavity. It was equal to 6000 m
/sec, i.e., about twice larger than
in 2007, which is probably explained by more intense precipitations over the Crimea in 2008.
Marine Hydrophysical Institute, Ukrainian National Academy of Sciences, Sevastopol, Ukraine.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
66–84, September–October, 2011. Original article submitted May 11,
2010; revision submitted May 24, 2010.
0928–5105/12/2105–0353 © 2012 Springer Science+Business Media, Inc. 353