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Local air mass dependence of extreme temperature minima in the
Gstettneralm Sinkhole with regard to global climate change
Benedikt Bica and Reinhold Steinacker
Department of Meteorology and Geophysics, University of Vienna, Austria; Benedikt.Bica@univie.ac.at
UZA II, Althanstraße 14, 1090 Vienna, Austria
1. Introduction
The 150-m-deep Gstettneralm sinkhole (1270 m asl) in the
eastern Austrian Alps is known for having recorded the
lowest temperatures in Central Europe (-52.6°C in February
1932). In 14 consecutive winters between 1928 and 1942,
the nocturnal temperature minima dropped at least eight
times below -50°C.
This historic data set is completed by measurements that
were collected in the course of a large field experiment
taking place in 2001/02 and by automatic temperature
registrations that have been carried out on a more limited
scale over the last eight years (Fig. 1).
appear to be higher as compared to the 1930s.
Min(T min ) Grünloch [°C]
20
15
r = 0.91
10
n = 39
5
0
-5
-10
-15
-20
-25
-30
-35
-40
-45
-50
-55
-60
0 5 10 15 20 25 30 35 40
Min(θ e ) Sonnblick [°C]
Figure 2. Scatterplot of correlations between
Min(θ e ) Sonnblick and Min(T min ) Gstettneralm based
on 40 day - intervals. Current data: 2001/10/18 -
2008/04/01.
Figure 1. Nocturnal temperature minima at the
bottom of Gstettneralm sinkhole between 2001/10/18
and 2008/05/12.
On the other hand, the Sonnblick observatory (Salzburg,
Austria, 3106 m MSL) provides one of the longest time
series in the Alpine region, with climate observations
ranging back as far as 1886. From Sonnblick observatory, in
addition to current data, a comprehensive set of observations
of the free atmosphere is available for the thirties of the last
century.
2. Evaluation of correlations
Both historic and current nocturnal temperature minima in
the sinkhole have been related to the respective prevailing
air mass properties in terms of equivalent potential
temperature θ e , which can easily be determined from
Sonnblick observations. Correlation coefficients up to 0.9
between these two locations prove that there is a significant
interrelation between Sonnblick air mass energy content and
Gstettneralm temperature minima (Fig. 2).
3. Problem
Between 2001 and today, nocturnal temperature minima
have never dropped below -50° although the ambient
conditions in the sinkhole, which is located in a very remote
area, should not have changed as compared to former times.
Direct anthropogenic influence can be completely excluded
at this place. Moreover, it was found that even under the
same air mass properties in terms of θ e , today’s minima
This raises the question if the observed reduction in the
amount of nocturnal cooling might be due to other reasons
such as changes in the radiation budget of the sinkhole.
4. Conclusions
It is well known that the amount of radiative nocturnal
cooling in a sinkhole strongly depends on the amount of
atmospheric back radiation: increased back radiation is a
distinct reason for an increased level of nocturnal
temperature minima in a sinkhole. On the other hand, the
interrelation of increased atmospheric greenhouse gas
concentration and changed radiative budget is beyond
dispute. We hypothesize that evaluation of historic and
current data from the Gstettneralm sinkhole help to
quantify the anthropogenic influence on climate change in
an innovative way.
References
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T.R. Karl, D.E. Parker, M.J. Salinger, V. Razuvayev,
N. Plummer, P. Jamason, C.K. Folland: Maximum and
Minimum Temperature Trends for the Globe. Science,
277, pp. 364 – 367, 1997
Sauberer, F., I. Dirmhirn: Über die Entstehung der
extremen Temperaturminima in der Doline Gstettner-
Alm (On the occurrence of extreme temperature
minima in the Gstettner-Alm Doline). Arch. Meteor.
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