DOI: 10.5194/tc-14-1779-2020
论文题名: Radar measurements of blowing snow off a mountain ridge
作者: Walter B. ; Huwald H. ; Gehring J. ; Bühler Y. ; Lehning M.
刊名: Cryosphere
ISSN: 19940416
出版年: 2020
卷: 14, 期: 6 起始页码: 1779
结束页码: 1794
语种: 英语
英文关键词: anemometer
; avalanche
; blowing snow
; hydrology
; model validation
; photogrammetry
; radar
; snow accumulation
; snow cover
; storm
; threshold
; turbulence
; wind velocity
英文摘要: Modelling and forecasting wind-driven redistribution of snow in mountainous regions with its implications on avalanche danger, mountain hydrology or flood hazard is still a challenging task often lacking in essential details. Measurements of drifting and blowing snow for improving process understanding and model validation are typically limited to point measurements at meteorological stations, providing no information on the spatial variability of horizontal mass fluxes or even the vertically integrated mass flux. We present a promising application of a compact and low-cost radar system for measuring and characterizing larger-scale (hundreds of metres) snow redistribution processes, specifically blowing snow off a mountain ridge. These measurements provide valuable information of blowing snow velocities, frequency of occurrence, travel distances and turbulence characteristics. Three blowing snow events are investigated, two in the absence of precipitation and one with concurrent precipitation. Blowing snow velocities measured with the radar are validated by comparison against wind velocities measured with a 3D ultra-sonic anemometer. A minimal blowing snow travel distance of 60-120 m is reached 10-20 % of the time during a snow storm, depending on the strength of the storm event. The relative frequency of transport distances decreases exponentially above the minimal travel distance, with a maximum measured distance of 280 m. In a first-order approximation, the travel distance increases linearly with the wind velocity, allowing for an estimate of a threshold wind velocity for snow particle entrainment and transport of 7.5-8.8 m s-1 , most likely depending on the prevailing snow cover properties. Turbulence statistics did not allow a conclusion to be drawn on whether low-level, low-turbulence jets or highly turbulent gusts are more effective in transporting blowing snow over longer distances, but highly turbulent flows are more likely to bring particles to greater heights and thus influence cloud processes. Drone-based photogrammetry measurements of the spatial snow height distribution revealed that increased snow accumulation in the lee of the ridge is the result of the measured local blowing snow conditions. © 2020 Copernicus GmbH. All rights reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/164616
Appears in Collections: 气候变化与战略
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作者单位: WSL Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, Davos Dorf, 7260, Switzerland; School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
Recommended Citation:
Walter B.,Huwald H.,Gehring J.,et al. Radar measurements of blowing snow off a mountain ridge[J]. Cryosphere,2020-01-01,14(6)