Baltic Sea Ice Climate Workshop 2005 
60 
Denmark - Gulf of Gdansk 
1920 1930 1940 1950 1960 1970 1980 1990 2000 
years 
♦ Dannish Waters ■ Gulf of Gdansk 
Fig. 1. Comparison of days with sea-ice on the Gulf of Gdansk and on the open waters of 
Danish Straits in 20 century. 
The high correlation coefficient (0.87-0.88) was calculated for the days with sea ice on fairways 
on Gulf of Gdansk and open waters in Danish Straits. It shows that in the majority of winters a 
method of correlation could be applied for reconstruction of sea ice conditions in Gulf of 
Gdansk. 
Sea ice conditions in Gulf of Gdansk in 15 century 
In 15 century the Baltic Sea was a very important trade route, dominated mainly by Hanza 
owing to assuring itself and the Union towns a favourable position. In Fig. 2 there are presented 
the main trade routes on the Baltic on the end of 15 and in 16 century. One of the longest one 
is Lübeck - Novgorod (till it was conquered by Russia), moreover the routes: southern - leading 
to The Polish - Lithuanian Federation (so-called Republic of the Both Nations) and the 
northern, leading to Sweden and Finnish towns. One may expect that a majority of accessible 
information concerning obstructions to navigation shall be referred to the above mentioned 
navigation routes.