Physical Oceanography, Vol. 16, No. 5, 2006
ANALYSIS OF OBSERVATIONS AND METHODS FOR CALCULATING
HYDROPHYSICAL FIELDS IN THE OCEAN
CHARACTERISTICS OF TRAPPED TOPOGRAPHIC WAVES
IN THE NORTHWEST PART OF THE BLACK SEA
A. A. Slepyshev and L. D. Pukhtyar
We study trapped baroclinic topographic waves in the northwest shelf of the Black Sea for the
actual slopes of the bottom and stratification. The time scales of trapped waves are determined.
The space scales of the amplitude of oscillations are computed. It is shown that the vertical
distribution of the amplitude of oscillations is in qualitative agreement with the experimentally
observed distribution. The energy of topographic waves trapped by the sloping bottom is con-
centrated in the bottom layer, which agrees with the data of measurements.
The investigation of the dynamic processes running in the bottom layer of the sea is quite actual in connec-
tion with the problems of utilization of shelf resources: exploration, extraction of raw materials, and construction
of drilling platforms and bottom transport facilities and pipelines. An important contribution to the dynamics of
the bottom layer is made by the wave processes running in the shelf zone. The influence of surface waves is de-
tected down to depths of about a half wavelength. At greater depths, the influence of internal and topographic
waves is predominant. The barotropic topographic waves similar to the shelf waves trapped by the coast and
Kelvin waves are fairly well studied [1–3]. The investigation of baroclinic topographic waves encounters serious
difficulties connected with the necessity of separation of the horizontal and vertical structures of motions caused
by the slope of the bottom [4–7]. For small slopes of the bottom, it is possible to separate the modes of oscilla-
tions by taking into account the slope of the bottom in the boundary condition [7, 8]. In the short-wave approxi-
mation, the energy of baroclinic topographic waves in a stratified sea is concentrated near the bottom, i.e., the
waves are trapped by the bottom [7, 8].
The physical cause of the existence of trapped bottom waves is the interaction of the gravitational and buo-
yancy forces on the one hand and inhomogeneities of the bottom topography and Earth’s rotation on the other
hand. The topographic waves play an important role in the total energy balance of motions of water in the shelf
zone because the shelf and the continental slope form a natural waveguide for these waves. The observation of
trapped topographic waves is quite difficult due to the complexity of measurements in the bottom layer. How-
ever, a few occurrences of these waves were recorded, in particular, on the shelf of the Peruvian coast .
The trapped topographic waves studied in  were observed according to the data of current meters. In the
present work, the baroclinic topographic waves were recorded according to the time dependences of the isolines
of temperature, salinity, and conventional density at different points of the test range.
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
44–52, September–October, 2006. Original article submitted March 28,
2005, revision submitted April, 26, 2005.
0928-5105/06/1605–0283 © 2006 Springer Science+Business Media, Inc. 283