Publication Date:
2023-06-19
Description:
Snow avalanches establish several flow regimes ranging from highly turbulent and intermittent flow in cold powder snow avalanches to the uniform plug flow sliding in warm dense flow avalanches. To assess the differences in this range of motions along the avalanche track, radar observations proved useful as they are independent of visibility conditions, but more importantly penetrate through the covering suspension powder cloud. Here we focus on data from Pulse Doppler radar that tracks the whole velocity spectrum in time and space. The temporal resolution is defined by pulses up to 10Hz, and a spatial resolution in range gates of 15 to 50m depending on the particular radar system.Our analysis allows us to distinguish between the frontal approach velocity along the line of sight as well as the material velocity at highest radar intensities and the maximum velocity for each range gate and pulse. Depending on the flow regime, these velocities reach up to 75 m/s. We compare material velocities at different length scales behind the front to characterize the flow regime, e.g., the intermittent flow is accompanied by surges that frequently overtake the avalanche front, whereas dense flow regimes are expected to have the highest velocities always at the front, represented by the approach velocity.Furthermore, we analyze the data of three avalanche paths in different snow climates and varying drop heights between 1400m, 900m and 300m. Our results may enable the development of flow regime specific computational avalanche simulation approaches and provide reference data for model valuation.
Language:
English
Type:
info:eu-repo/semantics/conferenceObject
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