Jökull - 01.12.1969, Blaðsíða 22

Temperature Variations in the North Icelandic
Coastal Area During Recent Decades
UNNSTEINN STEFÁNSSON
MARINE RESEARCH INSTITUTE, REYKJAVIK, ICELAND
ABSTRACT
Temperature variations in the North Ice-
landic coastal area in recent decades are exa-
mined on the basis of data collected at the
meteorological station Grimsey, sea surface
thermograph records and hyclrographic data. A
marked downward trend iri temperature and
salinity in both surface a.nd intermediate lay-
ers is indicated during the last 6 years, parti-
cularly in spring and summer. The main factors
likely to affect temperature variations in this
area are discussed. These factors include the
distribution of ice, past and concurrent mete-
orological conditions, changes in the character-
istics and relative magnitude of water masses
and fluctuations in the transport of Atlanti:
water to the Irrninger Sea. It is concluded that
in favourable ice years, the hydrographic situa-
tion north of Iceland is mainly determined by
past meteorological conditions at the west and
north coasts, whereas in heavy ice years the
distribution of drift ice is the dominating
factor.
ÍNTRODUCTION
It is well known that during the first de-
cades of this century marked changes occurred
in meteorofogical conditions of the northern
hemisphere. These changes were revealed not
only by a general increase in air and sea tem-
perature, but also by an intensification of the
atmospheric circulation, a recession of glaciers
and a retreat of the polar ice, particularly in
the period after 1920. Apparently, the sea tem-
perature reached a maximum between 1930 and
1940.
Variations in air temperature at several
meteorological stations in Iceland up to 1948
were studied by Eyþórsson (1949). His results
18 JÖKULL 19. ÁR
based on moving averages indicated a marked
increase in the annual air temperature in the
twenties, followed by a period of relatively
small changes between 1930 and 1948. The
temperature increase was greatest in winter and
spring, but smallest in summer and autumn.
Eypórsson also studied sea temperature varia-
tions at the station Papey off the southeast
coast, ancl found these to follow closely the
corresponding variations in air temperature.
Temperature variations in the North Ice-
landic coastal area up to 1950 were examined
by the author (Stefánsson 1954) on the basis
of measurements at the meteorological station
Grímsey during the period 1874—1950 and Dan-
ish material collected by commerical vessels in
the period 1896—1939 and published in the
Nautical Meteorological Annuals. At Grimsey
the same essential features were found to char-
acterize the sea and air temperature variations.
In the coastal area adjacent to and east of
Grímsey sea temperature variations were found
to correlate closely with those measured at
Grímsey, whereas in the western part of the
area the temperature fluctuations were signi-
ficantly different. In another publication (Ste-
fánsson 1962) year to year variations in hydro-
graphic conditions were studied for the periods
1924-1939 and 1947-1960.
Fig. 1. Location of stations referred to in the
text.