Physical Oceanography, Vol. 14, No. 6, 2004
ADVECTION MECHANISM OF REPLENISHMENT AND REFRESHMENT OF
THE COLD INTERMEDIATE LAYER ACCORDING TO THE RESULTS
OF NUMERICAL SIMULATION OF CURRENTS IN THE BLACK SEA
V. V. Knysh and N. V. Inyushina
We present the results of analysis of the advection mechanism of replenishment and refreshment
of the cold intermediate layer in the Black Sea. The analysis is based on the investigation of the
fields of temperature, salinity, density, currents, and the coefficient of vertical turbulent diffusion
obtained in the course of prognostic calculations according to the three-dimensional complete
model with seasonally variable external fields in boundary conditions. It is discovered that, par-
allel with winter convection, the cold intermediate layer in the central part of the sea is also re-
plenished and refreshed as a result of the transportation of cold waters formed in the northwest
part of the sea by currents.
1. The analysis of the mechanisms of formation of the cold intermediate layer in the Black Sea is one of the
most interesting and important problems connected with the formation of the hydrological structure of waters in
the active layer of the Black Sea.
In the early 1950s, Kolesnikov advanced a hypothesis on the advection nature of the cold intermediate lay-
er. According to this hypothesis, cold waters formed in the northwest region of the sea as a result of winter con-
vection are entrapped by the predominant currents and spread over the entire water area . Prior to this, the
convection hypothesis was prevailing. According to this hypothesis, waters of the cold intermediate layer are
formed as a result of winter convection in the entire basin (see, e.g., ). Most likely, due to the absence of re-
presentative data of observations, the advection mechanism of formation of the cold intermediate layer is poorly
studied in the scientific literature. In this connection, we mention the work , where, on the basis of the data of
February surveys of 1957 and 1958 in the west and northwest regions of the sea, the advection mechanism of re-
freshment of waters in the cold layer was confirmed and made more detailed. The authors of  have the same
opinion concerning the origin of the cold intermediate layer.
Later, in , the following conclusion was made on the basis of the analysis of the data on temperature and
salinity in a section made in the east part of the sea: The main sites of formation of cold waters in the Black Sea
are located at the centers of cyclonic circulations. These waters are formed as a result of winter penetrative con-
vection. The indicated mechanism was confirmed later in  on the basis of the data of measurements carried
out in the test ranges located in the central and northeast parts of the sea and in a hydrological section normal to
the Caucasian Coast.
In , the authors make an attempt to give a qualitative description of the process of formation of the cold
intermediate layer in the Black Sea within the framework of the multilayer quasiisopycnic model in which the
upper mixed layer is taken into account. Depending on the external factors, this layer may operate in the modes
of entrapment and subduction. The authors demonstrate that the cold intermediate layer is formed as a result of
subduction of waters from the upper mixed layer, formation of layers with relatively low temperature, and their
propagation over the entire sea.
The results obtained in  were checked in  with the help of adaptive numerical calculations performed
according to the quasiisopycnic model by using the monthly average climatic fields of temperature and salinity.
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol. Translated from Morskoi Gidrofizicheskii Zhurnal,
17–30, November–December, 2004. Original article submitted May 26, 2003; revision submitted June 2, 2003.
0928-5105/04/1406–0335 © 2005 Springer Science+Business Media, Inc. 335