Physical Oceanography, Vol. 18, No. 3, 2008
ANALYSIS OF OBSERVATIONS AND METHODS FOR CALCULATING
HYDROPHYSICAL FIELDS IN THE OCEAN
A QUASITROPICAL CYCLONE OVER THE BLACK SEA: OBSERVATIONS
AND NUMERICAL SIMULATION
D. A. Yarovaya, V. V. Efimov, M. V. Shokurov,
S. V. Stanichnyi, and V. S. Barabanov
A long-living mesoscale cyclone observed over the Black Sea in September 2005 was character-
ized by a high wind velocity
and induced an abnormal lowering of the sea-surface
temperature (by more than
We performed the numerical simulation of this cyclone by us-
ing the MM5 model and the data of global operative analysis. The evolution of the cyclone and
its structure similar to the structure of a tropical cyclone are reproduced. The primary azimuthal
and secondary radial circulations, the clear-sky eye with warm core at medium levels, and the
eyewall with strong air updraft and intense convection and precipitation are well visible. The
fluxes of sensible and latent heat on the sea surface played the key role in the initiation and
development of this cyclone.
The mesoscale structure of atmospheric circulation in the Black-Sea region remained poorly studied until
recently. At the same time, its investigation is required for the development of contemporary numerical methods
aimed the diagnosis and prediction of the variability of marine media. The most complete data arrays of long-
term NCEP/NCAR and ECMWF reanalyses have a space resolution of more than 1° in the latitudinal and lon-
gitudinal directions, which is insufficient for the adequate reproduction of mesoscale features connected with the
regional inhomogeneities of the surface topography, temperature, and roughness of the underlying surface. Only
with the development of new approaches, such as dynamic downscaling (i.e., regionalization or reanalysis with
higher spatial resolution)  and the appearance of contemporary satellite instruments, such as the QuikScat
scatterometer, it became possible to collect data on the surface wind fields with high spatial resolution. In the
present work, we study a quasitropical cyclone formed over the Black Sea at the end of September, 2005. The
development of this eddy and its action upon the marine media give a unique possibility for the verification of
atmospheric and marine models.
At the end of September 2005, an abnormally intense mesoscale cyclone (resembling a tropical hurricane)
developed in the atmosphere over the southwest part of the Black Sea. The cyclone had the so-called eye and its
diameter did not exceed
km. In the satellite photographs made on September 25–27, one can clearly see
spiral strips of clouds (see Fig.
4a in what follows). The analysis of temperature of the upper boundary of clouds
made it possible to show that, in the vertical direction, the cyclone reached the tropopause.
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol, Ukraine.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
41–55, May–June, 2008. Original article submitted July 26, 2006; revi-
sion submitted November 16, 2006.
154 0928-5105/08/1803–0154 © 2008 Springer Science+Business Media, Inc.