|
Early beginning of the ice season in the northern Baltic
(20 Nov. 2002)
Almost three weeks earlier than normal, the ice winter of 2002/03 has begun
in the northern Baltic. Since 20 October, longer frost periods in the northern
Bay of Bothnia and in the easternmost part of the Gulf of Finland led to
rapid cooling of the coastal water, completely using up the "heat reserve"
from summer and autumn which were clearly too warm. At the northern coast
of the Bay of Bothnia, first ice formed in the inner skerries in early November.
In the inner Bay of Kronstadt, the approach to St. Petersburg, ice formation
started ten days later. As navigation at the northern coast of the Bay of
Bothnia was expected to become difficult for low-powered vessels, the Ice
Service of the Federal Maritime and Hydrographic Agency started this year's
ice reporting on 15 November. The ICE REPORTS, issued daily from Monday through
Friday, provide detailed information on the ice situation and its development
in the entire Baltic area, ice and shipping conditions at the different observing
stations, restrictions to navigation due to ice, and operating areas of the
icebreakers. The ice charts issued with the reports show the areal extent
of ice formation as well as ice thickness and concentration.
This season, the first BSH ICE REPORT was issued two weeks earlier than average
(29 November). The earliest date in the past 35 years was 4 November (in
1968), and the latest date 20 December (in 2001). The last years in which
the first ice reports were issued at a similarly early date were 1998 and
1992. In both of these winters, the maximum extent of ice in the Baltic reached
average values. By contrast, the past three winter seasons began very late
(between 6 and 20 December).
Meanwhile, ice formation on the northern coast of the Bay of Bothnia has
continued. The ice thickness in the skerries presently is 5-25 cm, which
may pose difficulties to low-powered vessels in some areas. In the Finnish
harbours of Tornio, Kemi, and Oulu, restrictions to navigation concerning
icebreaker assistance (minimally 2000 tdw and Finnish-Swedish ice class II)
have been in force since 19 November. In the next few days, more severe frost
and increasing growth of ice are to be expected.
| 
