Glaziologische Untersuchungen im Sonnblickgebiet : Forschungsprogramm Wurtenkees

1995

143 S.

93 Lit. Ang.

Bandaufführung

31905

This summary, together with chapter headings, table and figure legends in English should allow some understanding of the paper also for non German speaking readers. The paper gives a synopsis of the glaciological research prpject Wurtenkees which has been carried out since 1982 in the Sonnblick region in the Austrian Alps. Wurtenkees is a small glacier south of the Alpine main ridge only a few kms away from Sonnblick observatory. It was chosen for intensive investigations because of its deviating retreat behaviour compared with that of adjacent glaciers, because of its vicinity to Sonnblick observatory with its more than 100 years long climatic time series on a mountain top of 3100m asl and because of the urgent need of glaciological research for more glaciers with direct mass balance data. Because of the large amount of field work necessary for such investigations, the number of mass balance data sets is rather small - also in the Eastern Alps (the region with highest spatial density of mass balance studies) there are only seven glaciers (including Wurtenkees) with at least 10 years mass balance data sets. Wurtenkees is the easternmost of them, situated in a mountain group with glaciers very sensitive for climate warming. Wurtenkees is an example for a glacier at the limit of its existence and therefore an interesting object of research in respect to recent climate change discussion, too. The main topics of the project are the following: To work up the historic data including photos, maps and length measurements (chaper 2), to carry out mass balance field measurements for winter, summer and anuual balances (chapter 3), to model mass balance using the climatic data set of Sonnblick (chapter 4) and to analyze snow chemistry of the winter snowpack (chapter 5). Processing of historic data shows a weak retreat of Wurtenkees during the period 1850 to 1920 (less than 200m length loss and 10% area loss), and after that a continuosly accelerating retreat of all size parameters (length, area, volume) up to now. Since 1930 Wurtenkees has belonged to the strongest retreating East Alpine glaciers and didn't show the recovering during the 1960ies and 70ies which was typical for most of the other Alpine glaciers. Up to now Wurtenkees has retreated about 1400m (western part) and 1900m (eastern part) from its maximum of 3500m around 1850. Now it covers 37% of its 1850 area, has lost about 50m of ice thickness (200m at the former terminus) and about 200 million tons of mass. During the 1970ies it has separated into two parts, one of which (the western one) is going to vanish completely in the near future under the actual climatic conditions. On the eastern part of the glacier field measurements were carried out since 1982/83 in May and September to determine specific mass balance for winter, summer and the whole budget year using the glaciological method. Those data bring new information into glaciology because of the above mentioned special characteristics of Wurtenkees and because of the winter balancing for which very few data are available elsewhere (none in the Eastern Alps). Climatological information about the vertical structure of temperature and density of the winter snowpack has been gained. The evaluationn of the mass balance maps underline the special characteristics of Wurtenkees, compared with other glaciers for which such data are available. Wurtenkees shows special features of vertical mass balance gradients with no continuous increase with height but a winter and summer maximum in an orographically shaded area in the central part of the glacier and minima in the lower and higher parts. There are high correlations between mean specific mass balance and accumulation area ratio (Sc/S) and the equilibrium line altitude as it is also known from other glaciers. Winter balance is not significantly correlated with summer and annual balance. This confirms the a priori assumption of Alpine glaciology that summer climate alo...