20 
A calculation of the differences between measured and modelled water levels at three 
stations on the German Baltic coast (Warnemünde, Sassnitz, Koserow) shows a bias 
between 19 and 24 cm for the hydrological years 1997 to 2000 (1 Nov. to 30 Oct., see 
Table 3). More important for the prediction service is the standard deviation of water level 
differences between measurement and model prognoses. At the 3 stations investigated, 
the value was between 7 and 12 cm. Table 2 also demonstrates that since 1999 the 
standard deviation has been reduced significantly, by approximately 20 %, due to use of 
the new model version. 
Table 3: Error statistics of water level predictions for three Baltic Sea stations 
Year 
Warnemünde 
Sassnitz 
Koserow 
Bias 
Std. 
Bias 
Std. 
Bias 
Std. 
dev. 
dev. 
dev. 
1997 
-19,9 
11,9 
-23,2 
9,3 
-20,4 
10,0 
1998 
-19,0 
11,3 
-23,8 
9,2 
-19,6 
9,8 
1999 
-19,2 
8,8 
-24,5 
6,8 
-21,2 
7,2 
2000 
-20,2 
9,3 
-23,3 
7,4 
-21,6 
8,0