The purpose of this years field test was to determine basic physical-acoustical ice parameters, especially the frequency dependency of the acoustic extinction length, as a basis for the system design of the acoustic sensor network and to perform a first in-situ test of a new melting probe prototype.
The field test was carried out in August 2015 on Hintereisferner in Austria. The test was kindly supported by the Institute of Atmospheric and Cryospheric Sciences situated at the University of Innsbruck. The Hochjoch Hospiz was used as base station.
The research team, which worked on Hintereisferner over a period of nine days, consisted of six scientists from Physics Institute III B, RWTH Aachen University and two scientists from the institute cluster IMA/ZLW & IfU, RWTH Aachen University. The first day was dedicated to the safety instructions for glacier novices as well as the exploration of the glacier, which was supported by Stephan Galos (Institute of Atmospheric and Cryospheric Sciences, University of Innsbruck). On the basis of his long lasting experience the scientists picked a suitable test site and took its GPS coordinates for the helicopter flight. On the next day the required measurement equipment was transported to the test site by helicopter. The first melt tests were performed parallel to the setting of the glacier camp. During the following six test days the scheduled measurements were carried out. In order to deploy the measurement equipment within the glacier the scientists needed to melt several measurement channels with a depth of up to 5m. For the acoustic measurements an emitter was placed in one of the measurement channels and a receiver was placed in a second measurement channel. The distance between emitter and receiver was varied by using different combinations of the measurement channels. The maximum distance between emitter and receiver was 100m. In addition the depth beneath the glacier surface was also varied. In parallel, further tests were performed with the melting probe prototype. In particular a 30m deep channel was melted and a melting velocity of about 2m/h was determined. The glacier exploration was also continued. When all measurements were finished the measurement equipment was removed from the glacier and transported back via helicopter.
In summary one can say that the field test on Hintereisferner was successful and the scientists were positively surprised by the good conditions at the test site. The cooperation with the University of Innsbruck was a great advantage since the test site was completely unknown to the research team prior to the test campaign. Preliminary data analyses show good results.
- Melting probe on frame: Dirk Heinen