Radar tracking of synthetic particles in snow avalanches

Innsbruck

2024

9 S.

Sonderdruck

13410S

40005491

In order to track particles within snow avalanches using high resolution radar, we develop and characterize an electronically amplifying radar reflector, known as an Active Target (AT). The AT, in conjunction with additional in-flow sensors, allows to analyze the flow dynamics of snow avalanches at the particle level. All measurements took place at the Nordkette mountain range above Innsbruck. The AT is analyzed and characterized including signal intensity changes with radar range. Initial tests for the moving AT scenario include roll measurements before the AT is directly placed in the avalanche. In addition to its primary function, the AT is used to calibrate the mGEODAR radar system itself by providing a known reference target to investigate ghost targets in the radar data due to internal hardware problems. The study confirms the functionality of the newly developed Active target in combination with the radar device. However, the AT antenna’s polarization and aperture require alignment of the AT with the radar beam. The signal intensity of the AT is at 40 dB for ranges larger than 200m and for lower ranges, the target appears with increasing intensities that causes widening of the normally discrete target peak in the radar data. This is of minor importance for the avalanche measurements at typical distances between 300m and 750m. Furthermore, those high intensity targets cause ghost targets at 207m and 412m in addition to the true target range. However, a comprehensive check of multiple radar settings does not reduce those mirror effects and the origin of the ghost targets can not be identified. One successful avalanche event has been measured with the AT and the in-flow sensor system. The rolling and flowing of the AT causes the tracked trace to appear as recurring peaks in the radar data. Nevertheless, the trace enables direct synchronization between the in-flow particle data and the radar device, and thus resolves the particle location with respect to the snow avalanche.