Radar measurements of blowing snow off a mountain ridge
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 understand...
Published in: | The Cryosphere |
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Copernicus Publications
2020
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00051675 2023-05-15T18:32:33+02:00 Radar measurements of blowing snow off a mountain ridge Walter, Benjamin Huwald, Hendrik Gehring, Josué Bühler, Yves Lehning, Michael 2020-06 electronic https://doi.org/10.5194/tc-14-1779-2020 https://noa.gwlb.de/receive/cop_mods_00051675 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00051331/tc-14-1779-2020.pdf https://tc.copernicus.org/articles/14/1779/2020/tc-14-1779-2020.pdf eng eng Copernicus Publications The Cryosphere -- ˜Theœ Cryosphere -- http://www.bibliothek.uni-regensburg.de/ezeit/?2393169 -- http://www.the-cryosphere.net/ -- 1994-0424 https://doi.org/10.5194/tc-14-1779-2020 https://noa.gwlb.de/receive/cop_mods_00051675 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00051331/tc-14-1779-2020.pdf https://tc.copernicus.org/articles/14/1779/2020/tc-14-1779-2020.pdf https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess CC-BY article Verlagsveröffentlichung article Text doc-type:article 2020 ftnonlinearchiv https://doi.org/10.5194/tc-14-1779-2020 2022-02-08T22:36:18Z 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. Article in Journal/Newspaper The Cryosphere Niedersächsisches Online-Archiv NOA The Cryosphere 14 6 1779 1794 |
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article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Walter, Benjamin Huwald, Hendrik Gehring, Josué Bühler, Yves Lehning, Michael Radar measurements of blowing snow off a mountain ridge |
topic_facet |
article Verlagsveröffentlichung |
description |
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. |
format |
Article in Journal/Newspaper |
author |
Walter, Benjamin Huwald, Hendrik Gehring, Josué Bühler, Yves Lehning, Michael |
author_facet |
Walter, Benjamin Huwald, Hendrik Gehring, Josué Bühler, Yves Lehning, Michael |
author_sort |
Walter, Benjamin |
title |
Radar measurements of blowing snow off a mountain ridge |
title_short |
Radar measurements of blowing snow off a mountain ridge |
title_full |
Radar measurements of blowing snow off a mountain ridge |
title_fullStr |
Radar measurements of blowing snow off a mountain ridge |
title_full_unstemmed |
Radar measurements of blowing snow off a mountain ridge |
title_sort |
radar measurements of blowing snow off a mountain ridge |
publisher |
Copernicus Publications |
publishDate |
2020 |
url |
https://doi.org/10.5194/tc-14-1779-2020 https://noa.gwlb.de/receive/cop_mods_00051675 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00051331/tc-14-1779-2020.pdf https://tc.copernicus.org/articles/14/1779/2020/tc-14-1779-2020.pdf |
genre |
The Cryosphere |
genre_facet |
The Cryosphere |
op_relation |
The Cryosphere -- ˜Theœ Cryosphere -- http://www.bibliothek.uni-regensburg.de/ezeit/?2393169 -- http://www.the-cryosphere.net/ -- 1994-0424 https://doi.org/10.5194/tc-14-1779-2020 https://noa.gwlb.de/receive/cop_mods_00051675 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00051331/tc-14-1779-2020.pdf https://tc.copernicus.org/articles/14/1779/2020/tc-14-1779-2020.pdf |
op_rights |
https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/tc-14-1779-2020 |
container_title |
The Cryosphere |
container_volume |
14 |
container_issue |
6 |
container_start_page |
1779 |
op_container_end_page |
1794 |
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1766216744173568000 |