Jökull - 01.12.1969, Side 58

gram was initiated by Russian scientists in the
thirties. In May of 1937 Papanin led an ex-
pedition where an observation station was built
on an ice island near the North Pole. This
station which was called “North Pole I”, was
manned for nine months while it drifted south-
ward along the coast of Greenland ancl finally
was abandoned in February 1938 off Scoresby
Sund. The Russian research vessel “Sedov”
started investigations of the ice drift when it
entered the ice west of New Siberian Islands
in October 1937 and drifted with the ice to-
wards the Greenland Sea. This expedition end-
ed on New Years Day 1940, when the ship
came out of the ice north of Spitzbergen. These
expeditions were discussed in reports by Shu-
leikin (1938), Zubov (1945), and Zubov and
Somov (1940). Zubov and Somov concluded
that the ice drift is parallel to the isobars of
the atmospheric pressure field with a velocity
proportional to the pressure gradient.
After World War II the Russian scientists
continued their Arctic research where they left
off at the start of the war and to date they
have had at least 15 manned Nortli Pole sta-
tions. In the late forties U. S. and Canadian
scientists started their own Arctic research pro-
grams and today they conduct continuous re-
search in the area using satellites, aircraft, and
submarines, as well as manned ice islands. The
drift of the ice island “Arlis II” whicli four
years ago drifted southward along Greenland’s
east coast all the way south to 67°, is still
fresh in the memory of all Icelanders. AIl these
investigations have contributed considerably to
the knowledge and understanding of the sea
ice behavior in the Arctic, and generally the
results confirm the Zubov-Somov rules about
the wind drift, which was discussed above.
Among works on the subject are papers by
Gordienko (1958), Gordienko and Laktionov
(1960), Vowinckel (1963), and Drogai.tsev (1956).
The last author points out, however, that the
direction of drift is about 10 degrees to the
right of the isobars rather than parallel to
them.
Most of the studies discussed above deal with
the Arctic and the results are based on wind
movements of continuous ice fields, i.e. ice of
10/10 concentration. These conditions of con-
tinuous ice fields and wincl drift primarily
54 JÖKULL 19. ÁR
exist over large areas of the Arctic where it is
estimated that up to 80 per cent of the ice
movement is caused by surface winds (Gordi-
enko 1960, Dunbar and Witlman 1963).
It is clear that conditions in the ocean cur-
rents transporting ice out of the Arctic, such
as the East-Greenlancl Current, are quite dif-
ferent from those in the Arctic. The ice is here
not continuous, i. e. the concentration is less
than 10/10, and the role of the current in
moving the ice is likely to be much greater.
Some authors have made attempts to take these
effects into account. Fukutomi (1948) derived
formulas for ice drift with variable concentra-
tion, but these formulas apply only for wind
drift and are therefore of limited use. The
same applies to Knodle’s work (1964). Felzen-
baum (1957), Reed and. Campbell (1962) and
Campbell (1964) made theoretical investiga-
tions of ice drift, where the effects of currents
ancl winds were taken into account, but these
studies were limited to continuous icefields.
The present author does not know of any
study where the effects of winds and currents
on ice drift of any concentration liave been
treated. This will say that satisfactory methods
to estimate the ice drift in the East Greenland
Current are not available, ancl it is the pur-
pose of this paper to deal with the condition
existing in this area.
EQUATIONS OF MOTION FOR SEA ICE
The forces acting on a floating sheet of ice
are many and varied. In the following it will
be assumed that the motion of the ice is in-
fluenced by the following five forces:
1. Wind-stresses at the air-ice interface, -j-a
2. Water stresses at the sea-ice interface, ts
3. Coriolis force, D
4. Pressure gradient force due to a sloping
sea surface, G
5. Internal stresses in the ice, R
Considering a unit surface area of the ice,
the equation of motion for the ice can be
written on the form
d2£
0th = ra + rs + I> + G + R (1)
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