Physical Oceanography, Vol.
ANALYSIS OF OBSERVATIONS AND METHODS FOR CALCULATING HYDROPHYSICAL
FIELDS IN THE OCEAN
HYDROMETEOROLOGICAL CHARACTERISTICS OF THE BLACK-SEA REGION IN
THE YEARS WITH EXTREME VALUES OF THE SARGASSO–BLACK-SEA INDEX
A. A. Sizov
and A. E. Chekhlan
We analyze the annual average values and the anomalies of some hydrometeorological characteristics
averaged over the period since January till March near the South Coast of Crimea and in the open part of
the Black Sea. It is shown that the sea-surface temperature, the surface temperature of air, and the at-
mospheric precipitation in the Black-Sea region are lower than the climatic mean values for the ex-
tremely high values of the index of North-Atlantic Oscillation (NAO index) (NAO 1) and the surface
temperature gradient between the Sargasso and Black Seas (SBS index) (SBS 1). In the years with
1 and SBS
1, the indicated characteristics exceed the climatic mean values. The entire
process of changes in the sign of anomalies of the hydrometeorological characteristics runs with a period
close to 20
The processes running in the zone of conjugation of the dry land with the sea in the Crimean region exert a
significant influence on the economic activities in the coastal zone. In numerous cases, they may lead to serious
material losses . In recent years, different researchers come to the conclusion that these processes are cyclic
[1–5] and, hence, it is possible to estimate the time scales of critical natural loads upon the coast.
The estimates of the trend components of some hydrometeorological characteristics and cyclonic activity in
the Black-Sea region obtained on the basis of series of various lengths [2–4, 6–8] are ambiguous. As one of the
causes of the indicated ambiguity of many-year trends, one can mention the atmospheric circulation [2, 6, 7].
Parallel with the trend component, the interannual and interdecadal variations of the temperatures of water
and air, atmospheric precipitation, and sea level were discovered in [2, 4, 6]. The scales of these variations were
estimated as follows: 3–5 [2, 4, 6] and ~
yr [1, 5, 9].
An attempt to relate the large-scale variations of the hydrometeorological characteristics to specific phases
of the development of atmospheric circulation was made in . It was shown that there exists a correspon-
dence between the extreme values of fluctuations of the hydrometeorological characteristics and the index of
atmospheric circulation. The role of this index was played by the NAO (North-Atlantic Oscillation) index. For
the description of the anomalies of surface temperature, it seems reasonable to use an index related to the surface
temperature gradient . As a result, the required index was chosen in the form of the surface temperature
gradient between the Sargasso and Black Seas.
Marine Hydrophysical Institute, Ukrainian National Academy of Sciences, Sevastopol, Ukraine.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
26–35, March–April, 2010. Original article submitted September 29, 2008;
revision submitted November 17, 2008.
0928–5105/10/2002–0099 © 2010 Springer Science+Business Media, Inc. 99