Physical Oceanography, Vol.
6, March, 2012 (Ukrainian Original No.
6, November–December, 2011)
ANALYSIS OF THE INFLUENCE OF BOTTOM TOPOGRAPHY
ON THE WIND CIRCULATION IN A TWO-LAYER BASIN
I. I. Karpatovich
We study the deep-water circulation in a closed basin with uneven bottom. The stratification is exam-
ined by the example of a two-layer model qualitatively describing the thermodynamics of small seas and
water basins. The effect of bottom topography is revealed by the method of comparison of the calcu-
lated current velocities in the lower layer for a basin with flat bottom and a basin with parabolic topog-
raphy. It is shown that, in a closed basin with uneven bottom, the current in the lower layer is more in-
Keywords: wind circulation, effect of bottom topography.
The present work is stimulated by the recent observations of the deep-water circulation of the Black Sea
with the use of floating-up buoys . The velocity of the observed deep-water currents in the Black Sea was
equal to 1–3 cm/sec on the average and sometimes was as high as 7 cm/sec. In the course of experiments, three
buoys were launched at the pycnocline depth of 200 m, in the intermediate layer at 750 m, and in a deep-water
layer at 1550 m. The data obtained from the first buoy indicate the active role of mesoscale eddies in the dy-
namics of the upper layer of the sea. The current velocity attained there 15 cm/sec along the axis of the Rim
current. The data from the buoys at the depth of the intermediate layer 750 m and at a level of 1550 m also con-
firm the influence of mesoscale eddies on the currents, though the velocities were at most 5 cm/sec there. In
addition, the characteristic trajectory of the buoy at a depth of 1550 m prior to its capture by a mesoscale eddy
passed along isolines of the function
, which indicates a significant effect of bottom topography on the
bottom currents. The circulation observed through the whole thickness of the sea was cyclonic without any
change in the direction near the bottom, as it happens in the ocean. Thus, the performed experiment gave a new
idea of the deep-water circulation in the Black Sea, since it was assumed earlier that the currents in the abyssal
part of this basin must be very weak. The idea of the weak circulation in deep-water layers aroused no doubt,
since the Black Sea possesses a sharply pronounced low-thickness pycnocline . Hence, if the stratification is
approximated within a two-layer model, then the current in the lower layer must be much weaker than in the up-
per one. The influence of bottom topography on the circulation was studied in some problems concerning the
oceanic scale – for some types of bottom topography. Insufficiently studied are the currents in closed ba-
sins, where the influence of topography can lead to qualitative variations in the structure of the deep-water circu-
lation. In this connection, we mention the results of , where the analytic study of the influence of a meridi-
onal slope of the bottom on deep-water currents was carried out. It was shown that such slopes can cause a sig-
nificant rearrangement of currents in surface and deep-water layers and can substantially intensify deep-water
currents in a closed basin.
Marine Hydrophysical Institute, Ukrainian National Academy of Sciences, Sevastopol, Ukraine.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
73–82, November–December, 2011. Original article submitted April 1,
2010; revision submitted June 24, 2010.
0928–5105/12/2106–0437 © 2012 Springer Science+Business Media, Inc. 437