Аннотация:Sea surface salinity is one of the major factor of the sea hydro-physics and ecology. Regional analysis of different phases during year cycle of the surface salinity shows it’s non-linear connections with freshwater budget for the Black Sea.
This work is devoted to combine analysis of atmospheric factors such as “precipitation minus evaporation” and large-scale atmospheric circulation and their possible influence to the sea surface salinity.
Climate estimation for the sea surface salinity is based on ship observations (more then 100,000 stations) during 1956-1995. On the base of this data seven main regions are identified with the specific water structure and dynamics: central, west and east frontal, west and east coastal, north-west and south-east estuarial. Monthly precipitation P and evaporation E for the same period are taken from NCEP/NCAR Reanalysis as well as zonal and meridional wind components at 850 hPa. Annual river discharge is also used.
Combined analysis of yearly (P–E) and river discharge showed that mainly (P–E) determines sea surface salinity even in coastal regions. River discharge influence is noticeable only in summer months. In the central part of the Black Sea as well as in coastal regions, minimum of salinity takes place in summer when (P–E)<0 and river inflow is the largest. In the central part minimum occurs one month later that in coastal parts. Precipitation is the strongest over eastern part of the Black Sea, so the sea water salinity near the Caucasus coast is relatively low.
Year course of monthly sums of (P–E) over the Black Sea shows significant spatial differentiation (fig.1a) which is in accordance of salinity data. Year mean zonal wind averaged over the sea allows to distinguish three circulation regimes with limits in the early sixties and middle seventies (fig1b). These periods are in agreement with regime shifts of sea surface salinity.