Jökull - 01.12.1991, Side 21

Finally, the cool period 1972-1990 shows less
deviations than 1965-1971, but the variation between
different parts of the country is reverse, partly
because no sea ice arrived in those years. It is of
interest to note that the negative deviations are larger
in the western part of the country than in the eastern
one. The summers were especially cold during this
period. It is not unlikely that air masses arriving from
west rather than north are causing this distribution.
CONCLUSION
In Iceland temperature is quite variable between dif-
ferent parts of the country. The cause is a combina-
tion of meteorological and oceanographic effects as
well as the mountainous character of the country.
The standard deviation shows a considerable vari-
ation of annual and monthly temperature from year to
year, thus indicating sudden changes of air masses
caused by extensive and frequent low pressure sys-
tems. Variations between different parts of the coun-
try are distinct. Especially in summer the standard
deviation in the northeastern interior is more than
twice the values in the southern part.
Based on the monthly standard deviation a sea-
sonal division is proposed in the following way: the
months January-March being winter, April-May
spring, June-August summer and September-
December autumn.
It is shown that variations from year to year of the
annual temperature are mostly in phase for the coun-
try as a whole. The same applies generally for the
months January-April and September-December.
During summer, monthly temperature variations in
different parts of the country are not at all in phase.
Considerable temperature variations have
occurred in Iceland during this century. Most signif-
icant are the very cold first two decades, a sudden
rise after 1920 followed by an unusually warm period
1926-1946. Since the end of this warm period tem-
perature has, with some irregularities, gradually been
decreasing.
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