Two-dimensional radar imaging of flowing avalanches

Radar has emerged as an important tool in avalanche research. However, existing radar sensors suffer from coarse range resolution capabilities. This limits the usefulness of the data they collect in validating models of avalanche dynamics. This paper details the development of a frequency modulated continuous wave, phased array radar, and its associated signal processing, for non-invasive measurements of entire avalanche events. The radar outperforms existing avalanche radar sensors in terms of range resolution, and it provides cross-range resolution using a phased array receiver. The radar has been operating at the Vallée de la Sionne avalanche test site in Switzerland since the 2010 winter season. It has successfully gathered measurements of entire natural avalanche events. In this paper we show two-dimensional radar images of a naturally occurring avalanche, the first of their kind, which reveal movements of layers or particles of the flowing avalanche in unparalleled detail. Furthermore, the potential of the measured data is shown with tracking of avalanche fronts in two spatial dimensions. This marks an important step towards providing a library of high-quality avalanche measurements to improve our knowledge of avalanche dynamics.