Influence of Sea Level Rise on the Dynamics of Salt Inflows in the Baltic Sea

Robinson Hordoir, Swedish Meteorological & Hydrological Institute, Oceanography Research Dept., Norrköping, Sweden, Lars Axell, Swedish Meteorological and Hydrological Institute, Oceanography Research Dept., Norrköping, Sweden, Ulrike Löptien, GEOMAR Helmholtz-Zentrum für Ozeanforschung, Kiel, Germany, Heiner Dietze, GEOMAR, Kiel, Germany and Ivan Kuznetsov, Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research Bremerhaven, Bremerhaven, Germany
Abstract:
The Baltic Sea is a marginal sea, located in a highly industrialized region in Central Northern Europe.
Salt water inflows from the North Sea and associated ventilation of the deep exert crucial control on the entire Baltic Sea ecosystem.
This study explores the impact of anticipated sea level changes on the dynamics of those inflows. We use
a numerical oceanic general circulation model covering both the Baltic and
the North Sea. The model sucessfully retraces the essential ventilation dynamics
throughout the period 1961 to 2007. A suite of idealized experiments suggests that
rising sea level is associated with intensified ventilation as salt water inflows
become stronger, longer and more frequent. Expressed quantitatively as a salinity
increase in the deep central Baltic Sea we find that a sea level rise of 1 m triggers a
saltening of more than 1 PSU. This substantial increase in ventilation is the
consequence of the increasing cross section in the Danish Straits amplified by
a reduction of vertical mixing.
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