Article

Time-dependent modeling of the Baltic entrance area. 2. Water and salt exchange of the Baltic Sea

Estuaries and Coasts (impact factor: 2.11). 03/2000; 23(2):253-266. DOI:10.2307/1352831 pp.253-266

ABSTRACT A time-dependent model for stratification and circulation within the Baltic entrance area (Gustafsson 2000) is tested against
observed salinities for the period 1961–1993. Although the Baltic Sea is one of the largest estuarine systems on earth, this
model could be applicable to smaller estuarine systems and embayments with tidal exchange. The seasonal cycle of freshwater
flux across the sill area does not follow the seasonal cycle of freshwater supply to the Baltic Sea. The seasonal variation
of the flux is a combined effect of the seasonal variation in freshwater supply, in Baltic mean sea level, and in dispersion
of salt across the sills. The seasonal variation in dispersion of salt is due to the seasonal cycle of sea level variability.
The model is used to predict the inflow of high saline water to the Baltic Sea. The resulting inflow time-series is consistent
with variations in the deep-water salinity and temperature in the deeper parts of the Baltic Sea. A comparison with previous
estimates of the magnitude of major Baltic inflows shows that the model is able to reproduce the characteristics fairly well
although the magnitude of the flows of water and salt appears lower than other estimates. It is shown that a climatic change
that increases the wind mixing does not significantly change the major inflows. Both increased amplitudes of sea level variations
in the Kattegat and decreased freshwater supply to the Baltic Sea substantially increase the magnitude of the inflows. It
is shown that deep-water renewal in the Baltic Sea is obstructed during years with high freshwater supply even if the sea
level forcing is favorable to a major inflow.

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Keywords

Baltic entrance area
 
Baltic Sea
 
climatic change
 
deep-water renewal
 
deep-water salinity
 
deeper parts
 
freshwater supply
 
largest estuarine systems
 
major Baltic inflows
 
major inflow
 
major inflows
 
resulting inflow time-series
 
saline water
 
sea level variability
 
sea level variations
 
seasonal cycle
 
seasonal variation
 
smaller estuarine systems
 
tidal exchange
 
time-dependent model
 

Bo G. Gustafsson