Abstract
Abstract. Avalanche risk management is strongly related to the ability to identify and timely report the occurrence of snow avalanches. Infrasound has been applied to avalanche research and monitoring for the last 20 years but it never turned into an operational tool to identify clear signals related to avalanches. We present here a method based on the analysis of infrasound signals recorded by a small aperture array in Ischgl (Austria), which provides a significant improvement to overcome this limit. The method is based on array-derived wave parameters, such as back azimuth and apparent velocity. The method defines threshold criteria for automatic avalanche identification by considering avalanches as a moving source of infrasound. We validate the efficiency of the automatic infrasound detection with continuous observations with Doppler radar and we show how the velocity of a snow avalanche in any given path around the array can be efficiently derived. Our results indicate that a proper infrasound array analysis allows a robust, real-time, remote detection of snow avalanches that is able to provide the number and the time of occurrence of snow avalanches occurring all around the array, which represent key information for a proper validation of avalanche forecast models and risk management in a given area.
Highlights
Operational avalanche forecast is based on the combination of observations and models of the snowpack and weather, which are validated by on-site observation of avalanche occurrence (McClung and Schaerer, 2006)
We validate the efficiency of the automatic infrasound detection with continuous observations with Doppler radar and we show how the velocity of a snow avalanche in any given path around the array can be efficiently derived
Our results indicate that a proper infrasound array analysis allows a robust, real-time, remote detection of snow avalanches that is able to provide the number and the time of occurrence of snow avalanches occurring all around the array, which represent key information for a proper validation of avalanche forecast models and risk management in a given area
Summary
Operational avalanche forecast is based on the combination of observations and models of the snowpack and weather, which are validated by on-site observation of avalanche occurrence (McClung and Schaerer, 2006). Infrasound (e.g., Bedard, 1989) and seismic observations (e.g., Schaerer and Salway, 1980) measure the energy radiated by the avalanche, respectively, in the atmosphere and in the ground, and are able to detect snow avalanches over large areas and moving along multiple paths. These different monitoring techniques have been used both during temporary experiments and operationally for real-time nowcasting. We perform analysis over the whole data set collected during the 2012– 2013 winter season and show eventually how infrasound can be efficiently used as a real-time early-warning system over large areas
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