Jökull - 01.12.1969, Síða 46

Fig. 11.
The mean
vertical density
distribution
in June 1950-
1958 in the
area studied.
The density
distribution
in 1965, 1967
and 1968
is shown
schematically.
a steady state unless ocean currents disturb the
balance.
The origin of the cold low-salinity water is
still unknown and whether an increased out-
ílow of Polar water from the north is involved
has not been confirmed. The origin of this
water may be north of Jan Mayen (Helland-
Hansen and Nansen 1909, p. 319), but local
conditions in the Iceland Sea may also be im-
portant.
In view of what has been said above, suggest-
ed future investigations of the ice conditions
in the Iceland Sea are the following: a) large-
scale observations of atmospheric conditions
over the Northern Seas as well as less exten-
sive observations in the Iceland Sea, b) con-
tinuous study of the distribution of drift ice
north of Iceland and c) intensive hydrographic
investigations in the waters north and east of
Iceland.
CONCLUSION
The main results of this paper indicate that
the proportion of Polar water has increased in
the Arctic water of the East-lcelandic Current
northeast of Iceland during the last years com-
pared to the period 1948—1958. That means
that the East-Icelandic Current which was an
Arctic current in 1948—1958 has developed in-
42 JÖKULL 19. ÁR
to a Polar Current in 1964—1968. An Arctic
current disfavours preservations and íormation
of sea ice because a slight vertical stratifica-
tion gradient in the surface layer of such a
current prevents the water masses to cool down
to freezing point without starting a vertical
convection. Polar currents, on the other hand,
transport sea ice as far south as the Polar
current maintains its characteristics: a strong
vertical stratification gradient due to low
salinity in the surface layer, a stratification
which will prevent a deep vertical convection
even at temperatures of — 1.8° C. Thus the
East-Greenland Current transports ancl even
preserves the polar ice from the North Polar
Sea.
The following may be concluded: There is
no ice in an Arctic current but conditions in
a Polar current favour sea ice. Thus a close
relationship is found between the drift ice
conditions in Icelandic waters, which were ex-
tremely unfavourable in the spring of 1965,
1967 and 1968, and the hydrographic condi-
tions in the East-Icelandic. Current. This rela-
tionship throws light on the physical causes of
the drift ice situation. Although the drift ice
situation is a complex one, depending upon
climatological factors, it is considered that once
the current has acquired this polar character
it promotes the formation of sea ice in the