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| Titel |
Gravity effect of glacial ablation in the Eastern Alps - observation and modeling |
| VerfasserIn |
P. Arneitz, B. Meurers, D. Ruess, Ch. Ullrich, J. Abermann, M. Kuhn |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250062420
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| Zusammenfassung |
| For the first time, this paper proves glacier ablation due to atmosphere warming by absolute
gravity observation results and its quantitative modeling. Absolute gravity observations
performed twice a year in Obergurgl (Austria) indicate a gravity increase of about
308 nms-2 since 1987 until present. Obergurgl is located at 1950 m close to the
main crest of the Eastern Alps and is surrounded by glaciers. The main approach to
explain the gravity increase is modeling of the mass deficit caused by glacial ablation.
Temporal elevation changes in glacial areas are provided by successive glacier
inventories of the Ötztal Alps (Abermann et al. 2009, 2011). Modeling is based on
high resolution DEMs (spacing varying from 5 to 8 m depending on the specific
inventory).
For glaciers in the Ötztal Alps, gravity effects of 81 nms-2 (1997-2006) and 122 nms-2
(1969-1997) were determined. The major contribution stems from the range up to 10 km
around Obergurgl. A gravity effect of about 22 nms-2 has been estimated for ice thinning
between 1969 and 2006 in the Stubai Alps.
After correcting the observed gravity time series for the total glacial ablation effect of 225
nms-2, a positive gravity trend is still visible. However, it shows weak statistical significance.
Its origin remains still open. Geodynamical processes like the uplift of the Alps or postglacial
deformation would contribute to a gravity decrease. Consequently, its correction would
increase the remaining trend.
The ablation impact on gravity explains about 2/3 of the observed gravity change. The
remaining trend observed in Obergurgl can be regarded as due to a mixture of hydrological
and geodynamical processes and instrumental uncertainties. In this context further glacier
inventories with high spatial resolution would be helpful as well as improved absolute
gravimeter technology. |
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