Air mass dependence of extreme temperature minima in the Gstettneralm Sinkhole with regard to global climate change

The 150-m-deep Gstettneralm sinkhole (Grünloch Doline, 1270 m MSL) in the eastern Austrian Alps is know for having recorded the lowest temperatures in Central Europe (-52.6°C in February 1932). In 14 consecutive winters between 1928 and 1942, the overnight temperature minima dropped eight times below -50°C. This historic Grünloch-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 four years. 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, a comprehensive set of observations of the free atmosphere is available for the thirties of the last century. In current works at the Department of Meteorology and Geophysics at the University of Vienna, efforts are being made to investigate the correlation of overnight Grünloch temperature minima and air mass properties as they can be derived from Sonnblick data. Correlation coefficients greater than 0.8 between these two locations prove that there is a significant interrelation between Sonnblick and Grünloch. Specific weight is given to the frequency of extreme temperature minima with respect to weather regime dependence. In the proposed presentation, both historical and current correlations will be opposed and discussed in the framework of global climate change.