30 
To analyse the empirical relationship between ice thickness and the sum of coldness in the 
Szczecin Lagoon, approximately 500 measurements of ice thickness made by the ice 
observers in Kamin, Kamminke and Ueckermiinde in the winters 1961-1990 were interpreted. 
The freezing process in waters like Szczecin Lagoon is determined primarily by the air 
temperature, other factors (water temperature, wind, snow) modifying this process to some 
extent. This fact is clearly evident in Figure 3.1 where the maximum ice thickness - i.e. the 
mean value of maximum ice thickness data measured at the three German coastal observation 
stations Ueckermiinde, Kamminke and Kamin in the winters from 1961 to 1990 - is shown in 
dependence on the sum of coldness representative of this region. 
60 
50 
O 
40 <D 
o 
7? 
3° = 
Cfl 
0) 
5' 
20 o 
3 
10 
0 
Winter 
Figure 3.1. Mean maximum ice thickness and measured sum of coldness (station 
Ueckermiinde) in Szczecin Lagoon in 1961 - 1990 
It was found that the equation h max = 2.12* K s 1/2 - 5.36 well describes (R 2 = 0.85, R - 
correlation coefficient) the variation of maximum ice thickness in the Szczecin Lagoon in 
dependence on the sum of coldness (Figure 3.2.). The dispersion of the measured data is 
mainly attributable to subjectivity of observations, local features of different observation 
stations, and variability in the occurrence of negative air temperatures (distribution of the 
monthly sum of coldness) in winter. In Figure 3.3, the mean maximum ice thickness 
measured in Ueckermiinde, Kamin and Kamminke in the ice winters of 1990/91, 1991/92, 
1992/93, 1993/94, 1994/95, 1995/96, 1996/97, 1997/98 and 1998/99 are shown in 
dependence on the sums of coldness reached in those years. Most ice thickness measurements 
can be represented with adequate precision by the empirically founded curve. 
Of higher practical interest is the possibility of forecasting ice growth during the ice season. A 
reliable forecast of air temperatures can be given for five to seven days at best. Therefore, we 
use the following equations, derived empirically for the area of Szczecin Lagoon and based 
on the data from the first ice formation to the first interruption of the ice growth process: