On pulsed Doppler radar measurements of avalanches and their implication to avalanche dynamics
- 作者：Peter Gauer ; Martin Kern ; Krister Kristensen ; Karstein Lied ; Lambert Rammer ; Helmut Schreiber
- 关键词：Avalanche ; Full-scale measurements ; Pulsed Doppler radar ; Velocity ; Acceleration
- 刊名：Cold Regions Science and Technology
- 出版年：2007
- 期刊代码：14_0165232x
- 类别：ear
- 出版时间：November 2007
- 卷：50
- 期：1-3
- 页码：55-71
- 文件大小：2374 K
摘要
Pulsed Doppler radar measurements from several avalanche releases are analyzed to gain an in-depth understanding of avalanche dynamics. A pulsed Doppler radar emits short pulses and samples the echo in distinct time intervals, corresponding to distance intervals (range gates). Frequency analysis of the echo signals, exploiting the Doppler-effect, yields the velocity distribution within the width of a range gate. Thus, it is possible to gain information on the front speed along the track and information on the velocity versus time at a specific location along the track.
In addition to the avalanche velocity, information on the magnitude of accelerations/decelerations along the track can be derived. To this end, the velocities of a pair of adjoining range gates are compared. The acceleration/deceleration values can give hints to parameters in the friction terms of commonly used numerical avalanche models. The derived retarding accelerations imply a behavior different to the one proposed in those models. They also indicate a dependency of the retarding acceleration on the stage of the flow.