Item: UNDERSTANDING METEOROLOGICAL CONTROLS ON WIND SLAB PROPERTIES
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Title: UNDERSTANDING METEOROLOGICAL CONTROLS ON WIND SLAB PROPERTIES
Proceedings: International Snow Science Workshop Proceedings 2023, Bend, Oregon
Authors:
- Nathalie de Leeuw [ Department of Earth Sciences, Montana State University, Bozeman MT, USA ]
- Karl Birkeland [ National Avalanche Center, Bozeman, MT, USA ] [ Birkeland Snow and Avalanche Scientific, Bozeman, MT USA ]
- Jordy Hendrikx [ Antarctica New Zealand, Christchurch, New Zealand ] [ Department of Geosciences, UiT the Arctic University of Norway, Tromsø, Norway ]
Date: 2023-10-08
Abstract: Wind-deposited snow has a broad range of possible physical and mechanical properties. The properties of a wind slab layer can vary greatly over short distances, creating difficult avalanche conditions. This variability causes particular challenges for avalanche workers in data-sparse regions where important snowpack information may be unavailable. Instead, snowpack properties are commonly inferred from available meteorological data. Though wind slab properties vary in space and time as meteorological conditions change, previous work has not explicitly studied these relationships at the slope-scale. In this research we aim to better understand how changes in meteorological variables relate to changes in wind slab physical properties. During two winters we recorded temperature, humidity, and wind speed at study sites in Montana's Madison Range and collected snowpack data during or immediately following blowing snow events. We found that average wind speeds at 0.5m and 1.5m above the snow surface were significantly higher during hard wind slab formation than soft wind slab formation, while unobstructed wind speed, maximum gust, and the length of time of wind transport were not associated with wind slab hardness. Temperature was higher during hard than soft wind slab formation, while relative humidity was not different between the two hardness categories. Although wind speed at 1.5m had a significant positive linear relationship with wind slab density, it was a poor predictor of actual slab density. Our findings help improve understanding of near surface winds and their impact on wind slabs, which will aid avalanche forecasting and mitigation planning particularly in windy climates.
Object ID: ISSW2023_O11.04.pdf
Language of Article: English
Presenter(s): Nathalie de Leeuw
Keywords: wind slab, wind transport, meteorological variables
Page Number(s): 1104 - 1111
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