The hydrographic-hydrochemical state of the Baltic Sea in 2012

The article summarizes the hydrographic-chemical conditions in the western and central Baltic Sea in 2012. Based on meteorological conditions, the horizontal and vertical distribution of temperature, salinity, oxygen/hydrogen sulphide and inorganic nutrients are described on a seasonal scale.

After the moderate to severe winters 2009/10 and 2010/11, the ice winter in the Baltic Sea was only moderate. With the “cold sum” of the air temperature in Warnemünde of 88.9 K d 2011/12 ranks on place 27 of the coldest winters since the beginning of the record in 1948, but remained below the long-term mean of 105.2 K d. The summer “heat sum” of 147 K d differs only marginally from the average of 149 K d since 1948.

In 2012, barotropic inflow events with estimated volumes between 100 and 300 km3 took place three times: in February/March, in August/ September and in December/January. The relatively strong inflow signal of November/December 2011 was registered in the Bornholm Basin only in February 2012. With an estimated input of one billion tons (1 Gt) of salts, the inflow can be characterized as a small Major Baltic Inflow (MBI). The transported oxygen amounted to more than 450 oo0 t. The inflow was strong enough to reach the southern Baltic Sea and the Gdansk Bight in spring 2012. In the deep water of the eastern and western Gotland Basin, however, the stagnation period has continuing undiminishedly.

Dr. Günther Nausch