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| Titel |
Local hydrological information in gravity time series: reduction and application |
| VerfasserIn |
M. Naujoks, C. Kroner, A. Weise, T. Jahr, P. Krause |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250029860
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| Zusammenfassung |
| Hydrological variations of up to some 10Â nm-s2 represent significant, broadband, and
integral information in temporal gravity observations. Thus, they can be considered as a
valuable supplement to traditional hydrological point measurements. Of particular interest is
to what extent such information can be used to improve the understanding of hydrological
process dynamics and to evaluate distributed hydrological models. In this context, a new
application of temporal gravity observations has been emerging: the study of natural
hydrological mass changes and their underlying processes.
Gravity data derived from GRACE satellite observations are affected by global and
regional hydrological variations. Continuous recordings from superconducting gravimeters
additionally contain information on local changes. Complementary to these data, repeated
gravity observations on a local network contribute to gaining additional local information on
spatial changes in hydrology and enabling a separation of the local hydrological influence
from regional and global changes.
To catch the local temporal hydrological influence on gravity of the hilly and
geologically inhomogeneous surroundings of the superconducting gravimeter at the
Geodynamic Observatory Moxa, Germany, interdisciplinary research has been carried out.
For an area of approximately 1.5Ã1.5Â km2 a hydrological catchment model was
combined with a well-constrained gravimetric 3D modell, which is made up of
nearly 29.000 triangles and achieves a resolution of 5 metres in the close vicinity of
the gravimeter. These combined modelling was used jointly with repeated gravity
observations on a local network to develop a high accuracy reduction for the local
hydrological signal in the continuous recordings of the superconducting gravimeter
with uncertainties of ±1.5Â nm-s2 for rain events and ±2.5Â nm-s2 for seasonal
variations.
Applying this reduction, the data of the superconducting gravimeter become suitable to be
interpreted with regard to changes in continental water storage. Clear continental seasonal
variations with a peak-to-peak amplitude of about 30Â nm-s2 are detected which were
previously masked by the local hydrology. This seasonal signal is also found in
variations based on the global hydrological model WGHM and in GRACE satellite
observations.
The evaluation of the local hydrological model based on the gravity modelling results and
the superconducting gravimeter data provided ideas for further enhancement of the internal
process representation in particular concerning the modelled effect of extreme hydrological
events such as heavy rain or snow melt. |
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