Influence of the Temperature on Ice Conditions in the Bay of Bothnia (Baltic Sea) 
27 
Evolution of the Virpiniemi ice 
thickness 
Frequential distribution of 
temperature (1957-2004) 
1991-92 
2002-03 
□ 
Slush 
Maximum 
Q3 
□ 
Snow 
Median 
□ 
Snow ice" 
Q2 
□ 
Clear ice" 
— 
Minimum 
□ 
Not frozen water 
Compared year 
Fig. 3. Ice thickness compared to the frequential distribution of temperature 
Sources : Station de Virpiniemi / llmatieteellinen Keskuslaitos - Station of Oulu 
Explications 
Low temperatures and small ice cover are responsible of the ice growth of the Bay of Bothnia. 
But other elements explain the formation and the evolution of the ice pack. The wind for 
example can induce important deformations of the ice cover. Boats which take channels made 
by ice breakers can have an influence on the deformation of the ice pack as well. So it seems 
important to take care about elements which can deform the ice cover or move the stations of 
measurement. The aquatic fauna can slow the ice growth.