On the influence of the freshwater supply on the Baltic Sea mean salinity

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Rodhe, Johan ; Winsor, Peter (2011)

The sensitivity of the Baltic Sea mean salinity to climatic changes of the freshwater supply isanalyzed. The average salinity of the Baltic Sea is about 6‰. The low salinity is an effect of alarge net freshwater supply and narrow and shallow connections with the North Sea. As aresult of mixing in the entrance area, a large portion of the outflowing Baltic Sea water returnswith the inflowing salty water and thus lowers the salinity of the Baltic Sea deep-water considerably.This recycling of the Baltic Sea water is a key process determining the salinity of today’sBaltic Sea. The sensitivity of this recycling, and thus of the Baltic Sea salinity, to climaticchanges in the freshwater supply is analyzed. A simple model is formulated for the variationsof the Baltic Sea freshwater content. Historical data of the freshwater supply and the salinityin the Baltic Sea are used in the model to achieve an empirical expression relating variationsof the recycling of Baltic Sea water to the variations of the freshwater supply. The recycling isfound to be very sensitive to the freshwater supply. We find that an increase of freshwatersupply of 30% is the level above which the Baltic Sea would turn into a lake. Recent climatemodeling results suggest that river runoff to the Baltic Sea may increase dramatically in thefuture and thus possibly put the Baltic Sea into a new state.DOI: 10.1034/j.1600-0870.2002.01307.x
  • References (2)

    Rodhe, J. and Winsor, P. 2002. On the influence of the freshwater supply on the Baltic Sea mean salinity. Tellus 54A, 175-186.

    Winsor, P., Rodhe, J. and Omstedt, A. 2001. Baltic Sea climate: an analysis of 100 yr of hydrographical data with focus on the freshwater budget. J. Climate 15, 5-15.

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