Jökull - 01.12.1991, Blaðsíða 14

Fig. 14 : Six classified main weather types: a) south-
eastem, b) southwestem or westem, c) southern with
warm air mass, d) eastem, e) northeastern, f) northem.
Mynd 14: Sexflokkar veðurlags: a) SA-átt, b) SV- eða
V-átt, c) S-átt með hlýindum, d) A-átt, e) NA-átt, f) N-
átt.
summer in the different parts of Iceland are available
(Einarsson, 1983). The number of days selected for
each of the weather types, i.e. having the same type
of weather during 24h, were 8-14 except for the
southern one with warm air mass, only 3. The maps
show that the variation of the minimum temperature
in summer between different parts of the country is
rather small compared with the corresponding varia-
tion of maximum temperature. One can therefore
imagine that the difference in maximum temperature
between the regions in question could give an
approximate picture of the extreme and unlikely tem-
perature conditions with one main weather type pre-
vailing a whole summer or a month.
Fig.15 shows a comparison using the same 4
weather stations as in Fig.ll, Reykjavík and Stóri-
núpur/Hæll in southwestern Iceland, Akureyri in
northem Iceland and Hallormsstaður in the eastem
inland. Four examples are given comparing for each
weather type the maximum temperatures in summer
and the correlation of July temperatures between
pairs of stations.
The correlation coefficient between the July tem-
peratures of Reykjavík and Stórinúpur/Hæll is very
high, 0.88. The maximum temperatures in summer
for the six main weather types confirm this nicely
and give a clear picture of the temperature conditions
for each type. At both stations the highest monthly
temperatures would occur if the weather types south-
ern, southeastern and eastern were dominating, but
the types southwestern, northern and northeastern
would give lower values. It looks like extreme
months would not deviate much from the regression
line for July. It is interesting to note that the weather
types probably giving maximum sunshine are not the
warmest ones in southwestern Iceland.
Correlation between the temperature of July at
Reykjavík and Akureyri is poor, 0.36. The extreme
maximum temperatures in different weather types
explain this clearly. At Akureyri there is a large dif-
ference between the cool northerly weather types and
the warm southerly ones compared with Reykjavík.
The figure confirms similar behavior of summer
temperatures in northem and eastem Iceland, i.e.
Akureyri and Hallormsstaður. The variation of the
weather types goes in the same direction both places
with low values in the northern and northeastern
types and high values in the eastern, southeastem,
southwestern and especially southem types.
Finally, it can be seen that there is almost no linear
regression between the July temperature at
Hallormsstaður and Stórinúpur/Hæll. The variations
are small and irregular at Stórinúpur/Hæll while they
can be very large between different weather types at
Hallormsstaður.
These examples show quite clearly that the varia-
tions from year to year of the summer temperature
are larger in northem and eastern Iceland than in the
12 JÖKULL, No. 41, 1991