The hydrographic-hydrochemical state of the Baltic Sea in 2008

The article summarizes the hydrographic-hydrochemical conditions in the western and central Baltic Sea in 2008. Based on the meteorological situation, the horizontal and vertical distribution of temperature, salinity, oxygen/ hydrogen sulphide, inorganic and organic nutrients are described on a seasonal scale.

In Warnemünde, the year 2008 was too warm on average and continued the series of positive anomalies whereby the warmer winter was more pronounced than the summer. This is mirrored also in extremely high sea surface temperatures during the first half of the year. The maximum ice cover of the Baltic Sea of 49 000 km² was the smallest one since recording started in 1720.

In 2008, five minor barotropic inflow events into the Baltic Sea with approximately 200 km³ took place: in January, February/March, June, September/October and November. These barotropic events as well as four baroclinic inflows in January, May, August and September reached the central Baltic Sea only partly in the form of single pulses and with different features. The near-bottom layer from the Bornholm Basin to the Gdansk Deep was ventilated again. In contrast, conditions in the eastern and western Gotland Basin were coined by the lasting stagnation period. In the deep water of the Gotland and Landsort Deep the highest hydrogen sulphide concentrations of the stagnation period which started in 2005 were measured. As a result, phosphate and ammonium concentrations in both deeps as well as in the Farö Deep were highest for the last five years.

Dr. Günther Nausch