a. What to look for?
a. What to look for?
realize that the sea ice conditions in winter 1941/42 in the Baltic have a
lot to do with naval warfare during the second half of 1941, there are
actually not so many aspects one needs to look at. There is the time of
commencement, the ice cover, the ice thickness, and how long the ice
lasted. In general terms it can be said, that icing started early in the
b. The Danish ice report (excerpts)
winter 1941/42 was extraordinary long lasting and cold in spite of
December having a mean temperature above normal. The first ice appeared on
November 4th, which is an extraordinary early date. Real ice
forming set in after January 7th and closed the fairways by
the end of January. The last ice disappeared by May 15th.
winter 1941/42 was quite unusual in character, long lasting and cold. Many
stations had more than 100 ice days, the maximum was 122 days. The ice
thickness averaged above 30 cm, and in a few places above 70 cm.
report includes 7 ice maps (between Jan 21. to April 12); each offering
specific characteristics for interpretation. Here only the ice map for
February 2nd 1942 is reproduced. Concerning the ice situation
(1953) mentioned a report on ice condition in the Kattegat and western
Baltic: “A remarkable occurrence was observed in Danish waters on
January 25 – forming of an ice bridge across the Öresund at Ven. On
January 31, at the end of the period now under review (end of Jan.1942),
freezing in the southern Central Baltic had progressed so far that,
according to the Swedish air reconnaissance flight report, heavy unbroken
ice was observable on the German coast and, some 35km or 20 nautical miles
further out, thin ice formed. The central part of the Baltic remained open.”
c. The Swedish ice report by G. Liljequist (excerpts)
formation and breaking up of the ice took place at a rather normal time in
the Gulf and
to prevailing easterly or north-easterly winds, heavy pack ice formed in
the Baltic along the Swedish coast.
with normal conditions the breaking up of ice was very late at the
West-coast and in the Baltic, especially in the Sound and the West-coast.
The sound was not ice free until the end of April and beginning of May,
which is about two month later than normal and the latest break-up since
1870 when regular ice observations started.
June 6th all Swedish waters were ice free. The thickness of ice
was about 100cm in the
prominent feature of the breaking up of the ice was the fact, that the
harbours and the river estuaries became ice free earlier than water further
out at sea. This seems to be the rule in sever ice winters.
the Baltic and the West-coast ice conditions in the winter 1941/42 became
generally worse than those in 1939/40 and 1940/41; in the Sea and the
ice period was generally longer than in 1939/40 but about the same as in
1940/41, except at the West-coast and in the Sound, where it lasted longer.
d. The Finish ice observer Erkki Palosuo
Erkki Palosuo (1953, pp. 33-88) served as
a reconnaissance pilot to observe sea ice during WWII. After the war he
studied meteorology and became a leading sea ice expert, with numerous
publications. This paper from which the first excerpts are taken on the ice
situation during the winter 1941/42 covers about 50 pages (see Fn.1). The
main focus will be given to the
freezing began earlier than usual in the northern part of the
new and comparatively hard period of frost began in the early part of
December. In the middle of December the open sea of the Gulf of Finland
was iced over throughout the field of view of the fixed observation
stations along the coast as far west as Pellinki.
‘openings’ of 10-15 metres in diameters appeared in the new ice in
January 6 a strong outbreak of arctic air mass began to push outwards from
the north of
bridge of fast ice formed in the
to stormy weather at the end of January existing sea ice was moving and
influenced ice condition in the open sea in the western
January 31, the eastern area of the
early February all available observations indicated a full ice cover,
including from a German source by February 5, that the entire Central
Baltic was covered by ice.
The information concerning a precise date when a full ice cover in
culmination of the ice winter was in the Kattegat and
last ice in the Gulf of Finland region was reported on May 27, in the
the ice thickness Palosuo (1981)
observed (Fn, 1): “The absolute greatest ice thickness on the Baltic
occurred during the severe winter of 1941/42. Thickness of up to 115cm was
measured in the northern
circumstances of the sea ice situation during winter 1941/42 offer
numerous clues of the relevance of naval warfare in
was clearly recognizable
in the northern regions of the central Baltic,
and in the
for the causal link with
operations in this sea
area. Further evidence can be drawn from the enormous thickness to
which icing grew. It was partly twice
the normal values. This
happened especially to a water body,
which had already greatly cooled
down before an ice sheet
formed. To understand this connection,
it requires no great effort
or experiments. This was demonstrated very practically at the Finnish
1953 ‚ “A Treatise on severe ice conditions in the central Baltic’,
Fennia 77, No. 1, Helsinki, pp. 127 (p.47); and
Erkki, (1981), “Absolute Greatest Thickness of Level Ice on the
Baltic Sea”, Geophysica Vol. 17, Nos. 1–2, p. 133-142.