Gravimetrie und deren Potential für eine unabh?ngige Bestimmung der Massenbilanz des Vernagtferners

摘要

Mass distribution and mass transport in the Earth System can be derived from analysis of the Earth's gravity field and its temporal variations. One of the contributors to gravity field variations is mass loss (or gain) due to melting (or accumulation) of ice and snow on glaciers and ice shields. On local scales of some few square kilometers terrestrial gravimetry is the only means of observing the tiny gravity field variations due to ice melting. But due to the large effort in carrying out repeated surveys in mountainous areas, the method is not very well established. However, the gravimetric method is the only method directly linked to mass variations and the corresponding estimates of mass balance need to be consistent with results inferred from other types of observation; inconsistencies might reveal misinterpretation of observations or coarse approximations in modeling. Because the mass balance of Vernagtferner is known very well from long time series of glaciological and geodetic (geometric) observations and because the glacier in its present state is not very dynamic, it is an ideal test field to validate the gravimetric method and analyze its potential for contributing to cryospheric mass balance studies. In 2010 and 2011, gravimetric observations have been carried out on Vernagtferner. The scope of the present paper is to describe these measurements and to present preliminary results on the consistency of geometric surface change and gravity change along a profile over the Schwarzwand area.