10 
2.2 Long - term variation of storm surges 
Because of the strong frequency fluctuation of surges, a presentation of the highest storm 
surges requires a compression of the linear time scale. Figure 2.1. shows the maximum 
water levels of the highest storm surges on a six-month basis (January-July / August- 
December), observed at the Warnemünde tide gauge between 1870 and 2000. 
water level The highest storm surges at Warnemünde 
in cm 
Fig. 2.1. Maximum water levels of the highest storm surges on a six-month basis 1870 - 2000 
The gaps during the 19 th century are due to missing data. Complete data are available for the 
20 th century. Verified data for the western part of the coast cover the years 1950 - 2000. 
Fig. 2.2 shows the distribution of the number of storm surges during the 1951 - 2000 
seasons. Each number is expressed as per cent of the total number of events that occurred 
in these years. One season covers the period from August of the preceding year to July of 
the year in question. The mean annual (seasonal) number of storm surges was slightly 
above 2 in this 50-year period. The highest number of surges, recorded in 1989/90, was as 
high as 7. Five storm surges were observed in the seasons 1973/74, 1988/89, 1991/92, and 
1997/98. As many as 8 seasons were free of surges (1956/57, 1965/66, 1966/67, 1968/69, 
1969/70, 1984/85, 1987/88, and 1990/91). 
Fig. 2.2. Number of storm surges recorded in particular seasons in Swinoujscie from 1950 to 
2000; in % of the total number of events that occurred in the second half of the 20 th century