14
According to this definition, there were 11 mild (36 %), 11 moderate (36 %) and 8 strong to
extremely strong (27 %) ice winters in the coastal waters area of Mecklenburg-Vorpommern
in the 30-year period from 1961 to 1990.
Mild
Moderate
Strong to extremely strong ice winters
1974/75
1961/62
1981/82
1982/83
1976/77
1968/69
1987/88
1977/78
1985/86
1988/89
1964/65
1984/85
1989/90
1975/76
1986/87
1973/74
1967/68
1978/79
1966/67
1970/71
1969/70
1980/81
1963/64
1962/63
1983/84
1965/66
1960/61
1979/80
1972/73
1971/72
The ice winters in each class show a similar behaviour. Koslowski [Koslowski, 1989]
described the characteristics of the five ice winter types for the Western Baltic Sea, and
Schmelzer [Schmelzer, 1994] did the same for the coastal areas of Mecklenburg-Vorpommern.
As a matter of experience, the ice conditions in the eastern waters of
Mecklenburg-Vorpommern differ essentially from those of the western part due to larger
influence of continental climate. It can be expected that the criterion of different ice winter
classes for the area under investigation shift to the larger values as already described for whole
coast of Mecklenburg-Vorpommern.
In Tables 2.3, 2.6 and 2.9, average and extreme values of ice parameters are presented for
mild, moderate and strong ice winters in the areas under investigation. The extreme data
indicated for each ice winter class rather are an exception and in most cases have been
reported only once at a single observation station. The range of the minimum and maximum
values for the number of days with ice, the duration of the ice season and the ice thickness is
too wide, even in comparable areas, to give a realistic picture of the ice situation in the
individual ice winter classes.
2.1. Meteorological and ice conditions in mild winters in the period 1961 - 1990
2.1.1. The meteorological conditions are described for the mild ice winter of 1988/89.
November
The first cold spell of this very mild winter season set in on 20 November. On 19 November,
a cold front passed over the Baltic Sea, followed by cold Arctic air. These conditions caused
air temperatures to decrease to negative values. Mean daily temperatures on the days 20 to 22
November ranged from about -3° to about -6°C in the region of Szczecin Lagoon. The water
temperature in Trzebiez decreased to 1.4°C during those days. On the last day of November,
after another violent intrusion of cold Arctic air from the North, a high pressure centre formed
over Scandinavia. During the following four days, it spread east, joining a high pressure
system over Russia. The air flow over the Baltic Sea changed gradually from northerly to
north-easterly and easterly.
