Jökull - 01.12.1969, Blaðsíða 35

13» |go |4o 12» 10” 8° 6°
Fig. 1. The region between Icelancl and Jan
Mayen Irom where all available hydrographic
observations in 1948—1968 were studied. The
current system is according to Stefánsson
(1962).
material and methods
All available hydrographic data (tempera-
ture and salinity) collected since 1948 in the
area within latitudes 67° to 69° N and longi-
tudes 11° to 15° W were studied. The area is
shown in Fig. 1. It was chosen with respect
to the current system in the Iceland Sea
(according to Stefánsson 1962, p. 57) and also
because a standard section has been worked
annually across the area, the Langanes NE—
Jan Mayen section. The material was col-
lected from the data lists of the International
Council for the Exploration of the Sea (Bull.
Hydr. 1947-1956, ICES ODL 1957-1963) and
the Marine Research Institute, Dept. ol
Oceanography, Reykjavík (1964—1968).
All the observations are from the summer
tnonths (April—September) and mostly from
June. The June data were therefore studied
specifically. They are available from 1950,
1952—1958 and 1964—1968. Data from July
1948 and 1949 ancl August 1951 were also in-
cluded in the study. No hydrographic data
tvere available from the area in question dur-
ing the years 1959-1963.
This material was analysed by t-S diagrams,
means of individual years and longer periods
were computed as well as the deviations from
means. Some typical features of the hydro-
graphy in the area in question are pointed out
and a study is made of the stratification in
the area in relation to vertical convection and
drift ice conditions.
RESULTS
In the t-S diagrams in Eig. 2 all observations
made during the years 1948—1958 are found
within a relatively narrow salinity range, be-
tween 34.72%0 and 34.92%c, with no tempera-
ture below — 1° C, but during the years 1964—
1968 there has obviously been an increase in
the Polar water component in the Arctic water
of the East-Icelandic Current. This is indicated
by salinities of 34.5—34.7%0 or even lower and
temperature values as low as — 1.8° C, as found
in 1965, 1967 and 1968. The trend towards
salinities of 34.7%0 and temperatures of —1.8° C
is of special interest and will be discussed
later. The difference in the hydrographic
Fig. 2. t-S diagrams for all available (mostly
June) hydrograpliic observations in the upper-
most 200 m in the area shown in Fig. 1. Ob-
served tcmperatures above 2° C are excluded.
JÖKULL 19. ÁR 31