A well-defined annual cycle has been observed
in the upper 50 meters of the Black Sea and inter-annual and
decadal variability have been estimated, primarily in the
coastal zone. By extending the duration of the available time
series and filling gaps in the data sets, we will be able
to assess long-term changes in deep-ocean areas. Some preliminary
results have already been obtained. They show a relatively
strong low-frequency signal that apparently is the response
of an enclosed sea to climatic changes in the Europe-North
Atlantic climate system (see figure).
In addition, a recently discovered new source
of deep-water formation in the Aegean Sea can likely be linked
to year-to-year fluctuations in the Black Sea outflow.
The Sound Speed Structure Many
aspects of Black Sea hydrography are poorly described in the
oceanographic literature. An important example is the Black
Sea sound speed structure. Undoubtedly this structure was
sufficiently investigated for practical uses but the results
were seldom published. The sound speed structure, as a reflection
of a particular thermohaline structure, has more in common
with the Baltic Sea or even the Nordic Seas than with the
adjacent Mediterranean Sea. This research will present not
only a general description of the mean sound speed field,
the SOFAR channel, and their statistical parameters but will
also describe the peculiarities in frontal zones caused by
local water exchange (river mouths, straits).