Physical Oceanography, Vol.
ANALYSIS OF OBSERVATIONS AND METHODS FOR CALCULATING
HYDROPHYSICAL FIELDS IN THE OCEAN
VARIATIONS OF THE SEASONAL BEHAVIOR OF GEOSTROPHIC CIRCULATION
IN THE BLACK SEA
A. B. Polonsky
and I. G. Shokurova
On the basis of the results of processing of the archival hydrological data, we analyze the seasonal be-
havior of geostrophic circulation in the Black Sea and its long-term variations. It is shown that the
variations of currents on the decadal time scales with different manifestations in different seasons lead to
changes in the characteristics of the seasonal course of geostrophic circulation in the second half of the
last century. The intensification of winter circulation and weakening of summer circulation observed
since the mid-1970s result in the increase in the amplitude of the annual course of current velocity on the
sea surface. We also discuss possible causes of variations in the intensities of geostrophic currents in the
The results of recent investigations of the characteristics of circulation in the Black Sea averaged over vari-
ous time intervals reveal the existence of their long-term variations. Thus, the numerical analyses carried out on
the basis of assimilation of the climatic hydrological fields reconstructed according to the data array accumu-
lated in 1903–2003 show that the Rim Current becomes more intense, especially in winter, as compared with
the Rim Current reconstructed according to the data array accumulated for a shorter period of time (1903–1982)
[1, 2]. The results of analysis of the decadal (ten-year) variability carried out in  by using the data accumu-
lated for the winter season in 1960–1990 reveal the existence of a trend toward the intensification of geostrophic
circulation in the surface layer of the sea and its weakening in the lower part of the pycnocline. In , on the
basis of the analysis of the data on temperature and salinity in “secular” sections of the Black Sea, a conclusion
was made that the circulation of waters became more intense in the zone of west cyclonic gyre at the end of the
winter season in 1960–1970.
In view of the revealed regularities, it is of interest to analyze the relative variability of circulation in the
Black Sea in different seasons on large time scales (~
50 yr) and the corresponding changes in the quantitative
characteristics of seasonal behavior.
In different periods of investigations, the character of seasonal variations of circulation in the Black Sea was
represented in different ways. The analysis of the data accumulated for the period since the 1920s till the early
10,000 stations) enables one to make a conclusion that the geostrophic circulation becomes more in-
Marine Hydrophysical Institute, Ukrainian National Academy of Sciences, Sevastopol, Ukraine.
Corresponding author; e-mail: email@example.com.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
16–31, January–February, 2010. Original article submitted August 26,
2008; revision submitted December 22, 2008.
14 0928–5105/10/2001–0014 © 2010 Springer Science+Business Media, Inc.