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| Titel |
Snow drift: acoustic sensors for avalanche warning and research |
| VerfasserIn |
M. Lehning, F. Naaim, M. Naaim, B. Brabec, J. Doorschot, Y. Durand, G. Guyomarc'h, J.-L. Michaux, M. Zimmerli |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 2, no. 3/4 ; Nr. 2, no. 3/4, S.121-128 |
| Datensatznummer |
250000271
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| Publikation (Nr.) |
 copernicus.org/nhess-2-121-2002.pdf |
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| Zusammenfassung |
| Based on wind tunnel
measurements at the CSTB (Jules Verne) facility in Nantes and based on
field observations at the SLF experimental site Versuchsfeld Weissfluhjoch,
two acoustic wind drift sensors are evaluated against different mechanical
snow traps and one optical snow particle counter. The focus of the work is
the suitability of the acoustic sensors for applications such as avalanche
warning and research. Although the acoustic sensors have not yet reached
the accuracy required for typical research applications, they can,
however, be useful for snow drift monitoring to help avalanche
forecasters. The main problem of the acoustic sensors is a difficult
calibration that has to take into account the variable snow properties.
Further difficulties arise from snow fall and high wind speeds. However,
the sensor is robust and can be operated remotely under harsh conditions.
It is emphasized that due to the lack of an accurate reference method for
snow drift measurements, all sensors play a role in improving and
evaluating snow drift models. Finally, current operational snow drift
models and snow drift sensors are compared with respect to their
usefulness as an aid for avalanche warning. While drift sensors always
make a point measurement, the models are able to give a more
representative drift index that is valid for a larger area. Therefore,
models have the potential to replace difficult observations such as snow
drift in operational applications. Current models on snow drift are either
only applicable in flat terrain, are still too complex for an operational
application (Lehning et al., 2000b), or offer only limited information on
snow drift, such as the SNOWPACK drift index (Lehning et al., 2000a). On
the other hand, snow drift is also difficult to measure. While mechanical
traps (Mellor 1960; Budd et al., 1966) are probably still the best
reference, they require more or less continuous manual operation and are
thus not suitable for remote locations or long-term monitoring. Optical
sensors (Schmidt, 1977; Brown and Pomeroy, 1989; Sato and Kimura, 1993)
have been very successful for research applications, but suffer from the
fact that they give a single flux value at one specific height. In
addition, they have not been used, to our knowledge, for long-term
monitoring applications or at remote sites. New developments of acoustic
sensors have taken place recently (Chritin et al., 1999; Font et al.,
1998). Jaedicke (2001) gives examples of possible applications of acoustic
snow drift sensors. He emphasizes the advantages of acoustic sensors for
snow drift monitoring at remote locations, but could not present any
evaluation of the accuracy of the measurements. We present a complete
evaluation of the new acoustic sensors for snow drift and discuss their
applications for research or avalanche warning. We compare the suitability
of sensors for operational applications. |
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