Physical Oceanography, Vol. 17, No. 6, 2007
STATISTICAL CHARACTERISTICS OF CYCLONES AND ANTICYCLONES
OVER THE BLACK SEA IN THE SECOND HALF OF THE 20TH CENTURY
A. B. Polonskii,
M. Yu. Bardin,
and E. N. Voskresenskaya
By using the NCEP reanalysis data for 1952–2000, we estimate the parameters of cyclones and
anticyclones in the Black-Sea region and evaluate the statistical characteristics of their variability
for each season. It is shown that the frequency of cyclones decreases in all seasons (except sum-
mer) as a result of the intensification of the North Atlantic Oscillation in the 1960–90s and the
displacement of the predominant paths of synoptic disturbances to the north. For anticyclones,
we reveal the opposite trend. The parameters of cyclones and anticyclones are characterized by
quasiperiodic variations on the subdecadal scale also induced by the North Atlantic Oscillation.
The synoptic variability of the atmospheric characteristics exerts the principal influence on the circulation
and structure of the Black-Sea waters. Thus, the predominance of cyclonic vorticity in the wind field formed
over the Black Sea in winter and the corresponding intensification of wind circulation are explained just by the
synoptic variations. The predominance of anticyclones in summer not only changes the sign of vorticity in the
wind field but is also accompanied by the elevation of the inflow of short-wave solar radiation (caused by the de-
crease in cloudiness) and weakening of the turbulent heat fluxes (due to the weakening of the wind). As a result,
the inflow of heat to the sea surface increases, which also affects the circulation and structure of waters. How-
ever, the role of synoptic processes in the formation of the structure and circulation of waters in the Black Sea is
not reduced to the indicated effects. Thus, the synoptic processes play the role of the main source of momentum
and mechanical energy transferred from the atmosphere into the sea. This follows from fairly simple considera-
tions published more than 35 years ago . Indeed, since the dependence of tangential friction stresses on the
sea surface on the wind velocity is nonlinear, the monthly average flows of momentum are largely (by more than
formed by storms. Strong storms accompanying deep cyclones whose frequency is quite low are of espe-
cial importance in this sense. The numerical analyses of the circulation of Black-Sea waters carried out by using
different models confirm this observation [2, 3].
The characteristics of cyclones and anticyclones in the European–Mediterranean region undergo significant
changes not only on the seasonal scale. The interannual and decadal variations connected, in particular, with the
North Atlantic Oscillation (NAO) are also readily detected [4–7]. Hence, the low-frequency variations of the
statistical characteristics of synoptic atmospheric processes (including the parameters of deep cyclones) caused
by the NAO determine the interannual and decadal variations of the circulation and structure of Black-Sea wa-
In the present work, we estimate the basic characteristics of cyclones and anticyclones in the Black-Sea re-
gion for four seasons according to the NCEP reanalysis data for 1952–2000 and study their correlation with the
Marine Hydrophysical Institute, Ukrainian National Academy of Sciences, Sevastopol.
Institute of Global Climate and Ecology, Russian State Committee on Hydrometeorology and Russian Academy of Sciences, Mos-
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
47–58, November–December, 2007. Original article submitted May 24,
2006; revision submitted July 3, 2006.
348 0928-5105/07/1706–0348 © 2007 Springer Science+Business Media, Inc.