Baltic Sea Ice Climate Workshop 2005 
58 
in these works are full of literary beauty, however to enable determination of winter severity in a 
numerical form (1- mild/extremely mild winter, 2 - moderate winter, 3- severe/extremely severe 
winter) it is necessary to take into account, among the others, the author’s nationality (i.e. for 
example such a winter which in Lithuania seems to be normal for any Lithuanian, according to 
anybody from South of Europe, who is visiting this country for the first time, may appear 
extremely sever winter.) 
Apart from the above, the contemporary works concerning maritime law and history of Gdansk 
have been employed. The mentioned publications include, among the others, information on 
legal regulations of Hanza Union forbidding (according to Lübeck regulations) sea navigation in 
winter season from 11 of November till 2/22 of February. However, this limitation was 
threatening for interests of Baltic’s members of Hanza, which at least 3 times in 16 century tried 
to change the regulation. Finally, neither entry confirming nor annulling the above Lübeck 
regulation was found in Gdansk journals of law. But it means that for example the information 
about entering the port by the first ship in February is not synonymous with a date of last ice 
melting, whereas entering the port in May can be identified with such a date. Another factor, 
which should be taken into consideration in analyzing dates of the first and the last ice 
occurrence, is converting from Julian to Gregorian calendar by some countries. 
Sea ice conditions on the Gulf of Gdansk in 20 Century 
Sea ice conditions on the Gulf of Gdansk were analysed (Stanistawczyk, Sztobryn 2004) on the 
basis of observations carried out in Gdansk area. Observations period started in winter 
1922/1923 and the records contain complete material, including data up to 2000 and further, 
except winter 1945/46. Probability of ice formation on this water area is 48%. In 1922-2000 time 
there occurred 39 winters with no ice (lacking of data of winter 1945/46). 
At the Gulf of Gdansk ice formation at the earliest occurs in the north -west part of the Puck 
Bay and above the coastal shoals nearby Jastarnia, then in the coastal zone near Gdynia and 
Gdansk, at the latest the first ice shows up close to the Town of Hel. The most often there 
appear new ice or floe. 
In Table 1 there are presented parameters of ice formation for the analysed (for winters with 
ice) on the Gdansk fairway. The first ice in this water area appears on 26 January on the 
average, and melts on 28 of February. On the average there occurs about 10 days with ice 
within one ice season, whereas duration of ice season is 16 days.