Jökull - 01.12.1991, Blaðsíða 19

Fig.19 : 10-year overlapping
means of temperature of the four
seasons 1901-1990 at Reykjavík
and Akureyri.
Mynd 19:10 ára raðmeðaltöl ein-
stakra árstíða 1901-1990 í
Reykjavík og á Akureyrí.
In continuation of the favourable, warm period,
1926-1946, the main tendency of the temperature
curves for all seasons and in all parts of the country is
a descent to the present, though with the disturbance
of the two cool periods 1947-1952 and 1965-1971.
The former one is most distinct in spring and autumn
but hardly seen on the other curves except for
Reykjavík in winter. The latter period is distinguish-
able at Akureyri especially in winter and spring but
not at all seen at Reykjavík.
In Fig.20 the deviation of annual mean tempera-
ture from the 50-year annual mean temperature
1936-1985 is presented for the periods 1901-1925,
1926-1946, 1947-1952, 1953-1964, 1965-1971 and
1972-1990. As described in a former chapter there
seems to be a minimal difference between averages
for the 50-year period and the period 1901-1990 as a
whole. It must be pointed out that the chart for the
first period is based only on 7 weather stations and in
addition an estimated value for an eighth one. For the
second period, 1926-1946, the stations are 17 and for
the four periods left the 32 selected stations are used.
The deviation for 1901-1925 is negative in all
parts of the country with maximum deviation in
northem and eastern Iceland but minimum values in
the southwestem part. The chart for the warmest peri-
od in question, 1926-1946, is completely different
from other periods. The positive deviations show a
minimum along the coasts except at Reykjanesskagi
in southwestern Iceland and Melrakkaslétta in the
northeastern part. They increase otherwise towards
the interior.
It has been pointed out that the cool period
1947-1952 is only distinct in some parts of the coun-
try and only during a part of the year. It is therefore
to be expected that the deviations are small and
irregular, in most regions in the interval 0.0°C to
-K).2°C. Positive values are mainly found in the
northeastern part of the country.
The deviations of the annual temperature for the
rather warm period 1953-1964 are small, of the
order 0.3°-0.5°C, with the lowest values in southern
Iceland, 0.2°-0.3°C.
For the next period, the sea ice period 1965-1971,
having negative deviations, the difference between
different parts of the country is larger than for other
periods. The coldest area is the north coast and in
general the northern and eastern Iceland. The devia-
tions decrease towards south and southwest. Rather
obvious influence of sea ice and low sea surface tem-
perature are indicated by the largest negative devia-
tions in winter, especially in March.
JÖKULL,No. 41, 1991 17