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Start Over Author "Wilhelms, F." Publisher international glaciological society
8 results on '"Wilhelms, F."'

3. Density log of a 181 m long ice core from Berkner Island, Antarctica

Author

Gerland, S., Oerter, H., Kipfstuhl, J., Wilhelms, F., Miller, H., Miners, W. D., Gerland, S., Oerter, H., Kipfstuhl, J., Wilhelms, F., Miller, H., and Miners, W. D.

Abstract

A 181 m long ice core was drilled at 79°36′51″ S, 45°43′28″ W, near the summit of Berkner Island, Antarctica (886 m a.s.l.). Berkner Island is located between the Filchner and Ronne Ice Shelves, and the ice near the summit shows little lateral flow. The density of the ice core was measured every 3 mm along its length, using attenuation of a gamma-ray beam, which gave an absolute accuracy of 2%. As expected, there is a general density increase with depth, the maximum densities of > 900 kg m−3 being reached just above 100 m depth. Comparison with the electrical conductivity method (ECM) shows density variations with the same wavelength as the annual signals, which can be seen in the ECM log (higher acidity during summer). In the shallowest part of the core, the density of winter layers is higher than that of summer layers, a relationship which is reversed at greater depth. We assume that the densification rates for the two types of firn are different. Similar density phenomena were observed on ice cores from Greenland, showing that such phenomena are not a local effect.

Published
1999

5. Spatial gradients in snow layering and 10 m temperatures at two EPICA-Dronning Maud Land (Antarctica) pre-site-survey drill sites

Author

Holmlund, P., primary, Gjerde, K., additional, Gundestrup, N., additional, Hansson, M., additional, Isaksson, E., additional, Karlöf, L., additional, Nman, M., additional, Pettersson, R., additional, Pinglot, F., additional, Reijmer, C. H., additional, Stenberg, M., additional, Thomassen, M., additional, van de Wal, R., additional, van der Veen, C., additional, Wilhelms, F., additional, and winther, J.-G., additional

Published
2000
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8. Accumulation rates in Dronning Maud Land, Antarctica, as revealed by dielectric-profiling measurements of shallow firn cores

Author

Oerter, H., Wilhelms, F., Jung-Rothenhäusler, F., Göktas, F., Miller, H., Graf, W., and Sommer, S.

Subjects
13. Climate action, 530 Physics
Abstract

The European Programme for Ice Coring in Antarctica includes a comprehensive pre-site survey on the inland ice plateau of Dronning Maud Land, Antarctica. The German glaciological programme during the 1997/98 field season was carried out along a 1200 km traverse on Amundsenisen and involved sampling the snow cover in pits and by shallow firn cores. This paper focuses on the accumulation studies. The cores were dated by dielectric-profiling and continuous-flow analysis. Distinct volcanogenic peaks and seasonal signals in the profiles served to establish a depth time-scale. The eruptions of Krakatoa, Tambora, an unknown volcano, Kuwae and El Chichon are well-documented in the ice. Variations of the accumulation rates over different times were inferred from the depth time-scales. A composite record of accumulation rates for the last 200 years was produced by stacking 12 annually resolved records. According to this, accumulation rates decreased in the 19th century and increased in the 20th century. The recent values are by no means extraordinary, as they do not exceed the values at the beginning of the 19th century. Variations in accumulation rates are most probably linked to temperature variations indicated in δ18O records from Amundsenisen.

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