Baltic Sea

1. Introduction
1.1 Investigations of spatiotemporal scales in the Baltic
Proper
The Baltic Sea is mainly surrounded by land, thus water exchanges with the North Atlantic
Ocean take place indirectly through transition areas such as the Kattegat (K), which connects
the Baltic Sea with the North Sea. To reach the Baltic Sea, its waters have to pass through
the narrow sound and straights. All inowing water is topographically trapped for a certain
time in several deep basins, which are connected by channels and separated by shallow sills
of dierent depth. The largest basin of the Baltic Sea is the Eastern Gotland Basin (EGB)
with a maximum depth of 249 m. Due to its landlocked position and large amounts of river
run-o the Baltic proper is strongly stratied and the density is predominantly determined by
salinity. Between 60 - 90 m a strong halocline prevents mixing of the whole water column in
the EGB. Exchanges of saline and oxygen-rich waters from the North Sea occur sporadically
yet are essential for the ventilation of the deep EGB, since dense water masses travel along
the bottom. Driving mechanism of inows are well investigated (Matthäus and Franck,
1992), but associated spatiotemporal eects are still subject to research and crucial for the
understanding of overall mechanism. The majority of inows occur as barotropic inows
between November and January, the so-called 'inow season' (Matthäus and Franck,
1992), when the water column in the Kattegat is well mixed and oxygenated. However, not all
inows are cold, oxygen-rich inows, especially when the inow occurs in summer under calm
wind conditions. These inows still manage to exchange the deep layers of the EGB, but not
with the desired eect of renewing the oxygen.
The following questions arise from the eects saline inowing water masses from the North
Sea have on the deep water of the Baltic Sea and will be addressed in this thesis: What kind
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