13 
2. Classification of ice winters in the area of the Polish-German border waters. 
Below we will describe the course of the ice winters in Polish-German border waters and finally 
give the characteristics of different ice winter types for this area. 
To estimate the severity of ice winters in the area of the Polish-German border waters, we use 
the accumulated areal ice volume (Vax) as a parameter. The accumulated areal ice volume 
[Koslowski, 1989] is given by 
n j k 
where n = number of stations, N = ice concentration, H = ice thickness, j = index of days 
with ice for the winter, k = index of station. 
The accumulated areal ice volume was calculated for the Baltic coast of Schleswig-Holstein 
[Koslowski, 1989], for the Baltic coast of Mecklenburg-Vorpommern [Schmelzer, 1994] and 
for the whole German Baltic coast [Koslowski and Glaser, 1995]. 
The distribution of accumulated areal ice volume (Vax) for the whole coast of Mecklenburg- 
Vorpommern in the time interval between 1961 and 1990 is shown in Figure 2.1. 
<'5©0Nr'-l/i'OO\«Nr*©'CTt© — O0'£>Vir~0CfSf' , >-<'i—>r--TrV)r)00O\© 
\Or~t^OC aOCO'OOCr^OO \OVO\Or~\Or^V3r~r~-VCr'\Oi»OOVO»-'r^OOOOOCON 
On On On On On On On On On On On On On On On On On On On On On On On On On On On On On On On 
Figure 2.1. Accumulated areal ice volume for the coast of Mecklenburg-Vorpommern in the 
period 1961-1990 
It is obvious, that ice conditions in the coastal waters are very variable from season to season. 
There are some winters of comparable characteristics. Koslowski [Koslowski, Glaser, 1995] 
defined the following five ice winter classes, which were derived from the frequency distribution 
of Vax for the German Baltic coast as follows: mild < 0.50 m < moderate < 4.00 m < strong < 
9.00 m < very strong < 20.00 m< extremely strong.