Jökull - 01.12.1991, Side 9

MEAN TEMPERATURE FOR THE 50-YEAR
PERIOD 1936-1985
The 50-year period 1936-1985 was chosen to
describe the temperature conditions in Iceland in
some detail. The choice was primarily based on the
fact that 29 of the 32 selected weather stations were in
function during that period. Secondly, there is a min-
imal difference between average temperatures of the
period 1901-1990 and the chosen one for the 7 sta-
tions already in operation in 1901. The annual mean
temperature 1936-1985 is only 0.1°-0.2°C higher
than for 1901-1990 and the same applies for the win-
ter temperature (January-March). For the summer
months (June-August) the difference is +0.1 °C.
The author has previously published maps show-
ing the mean temperature of January and July in
Iceland for the normal period 1931-1960 (Einarsson,
1984). As will be described later this was a rather
warm period. Therefore it is not surprising that the
50-year mean values of January and July are lower
for all parts of the country. In January the difference
is of the order of 0.5°C in northern and eastem
Iceland, 0.3°C in western Iceland but 0.1°-0.2°C in
the southern part. The corresponding difference for
July is of the order of 0.1°-0.6°C with a rather irreg-
ular distribution when comparing different parts of
the country.
Figs.7-10 show maps, for the 50-year period
1936-1985, describing annual mean temperature,
annual range of temperature, winter temperature and
summer temperature, respectively. In addition to the
selected stations, values for 49 other weather stations
with available calculated normal values 1931-1960,
were estimated by comparing the 29 stations in oper-
ation during both periods. Therefore the maps are
actually based on 78 weather stations. For all the
maps it must be bom in mind that highland values are
not well known because of lack of observations.
Annual mean temperature 1936-1985 is seen in
Fig.7. The highest values, 5.5°C, are found in the
southernmost coastal areas. In southem Iceland the
annual values are 4°-5°C in the lowland areas. In
eastern and western Iceland the lowland values are
generally 3°-4°C. In the northern part of the country
a temperature of 3.5°C is reached at a few stations
but is otherwise 2°-3°C and even below 2°C in the
coolest inhabited areas.
In general annual temperature decreases towards
the interior. An exception is Fljótsdalshérað in east-
ern Iceland where the values are up to 1°C higher in
the inner part. Weather types with mild southerly
winds seem to have a better access to the inner part
than the outer one in winter (Einarsson, 1983). This is
also reflected in the map for winter temperature
(Fig.9).
Fig.7 : Annual mean temperature
1936-1985,°C.
Mynd 7: 50 ára ársmeðalhiti
1936-1985, °C.
JÖKULL, No. 41, 1991
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