气候变化领域集成服务门户(CCPortal): Radar measurements of blowing snow off a mountain ridge

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DOI	10.5194/tc-14-1779-2020
	Radar measurements of blowing snow off a mountain ridge
	Walter B.; Huwald H.; Gehring J.; Bühler Y.; Lehning M.
发表日期	2020
ISSN	19940416
起始页码	1779
结束页码	1794
卷号	14 期号:6
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.
英文关键词	anemometer; avalanche; blowing snow; hydrology; model validation; photogrammetry; radar; snow accumulation; snow cover; storm; threshold; turbulence; wind velocity
语种	英语
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202238
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
推荐引用方式 GB/T 7714	Walter B.,Huwald H.,Gehring J.,et al. Radar measurements of blowing snow off a mountain ridge[J],2020,14(6).
APA	Walter B.,Huwald H.,Gehring J.,Bühler Y.,&Lehning M..(2020).Radar measurements of blowing snow off a mountain ridge.Cryosphere,14(6).
MLA	Walter B.,et al."Radar measurements of blowing snow off a mountain ridge".Cryosphere 14.6(2020).