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4. A novel framework to investigate wind-driven snow redistribution over an Alpine glacier: combination of high-resolution terrestrial laser scans and large-eddy simulations.

Author

Voordendag, Annelies, Goger, Brigitta, Prinz, Rainer, Sauter, Tobias, Mölg, Thomas, Saigger, Manuel, and Kaser, Georg

Subjects
ALPINE glaciers, MASS budget (Geophysics), SNOW accumulation, DIGITAL elevation models, METEOROLOGICAL research, METEOROLOGICAL stations, WEATHER forecasting
Abstract

Wind-driven snow redistribution affects the glacier mass balance by eroding or depositing mass from or to different parts of the glacier's surface. High-resolution observations are used to test the ability of large-eddy simulations as a tool for distributed mass balance modeling. We present a case study of observed and simulated snow redistribution over Hintereisferner glacier (Ötztal Alps, Austria) between 6 and 9 February 2021. Observations consist of three high-resolution digital elevation models (Δx=1 m) derived from terrestrial laser scans taken shortly before, directly after, and 15 h after snowfall. The scans are complemented by datasets from three on-site weather stations. After the snowfall event, we observed a snowpack decrease of 0.08 m on average over the glacier. The decrease in the snow depth can be attributed to post-snowfall compaction and the wind-driven redistribution of snow. Simulations were performed with the Weather Research and Forecasting (WRF) model at Δx=48 m with a newly implemented snow drift module. The spatial patterns of the simulated snow redistribution agree well with the observed generalized patterns. Snow redistribution contributed -0.026 m to the surface elevation decrease over the glacier surface on 8 February, resulting in a mass loss of -3.9 kg m -2 , which is on the same order of magnitude as the observations. With the single case study we cannot yet extrapolate the impact of post-snowfall events on the seasonal glacier mass balance, but the study shows that the snow drift module in WRF is a powerful tool to improve knowledge on wind-driven snow redistribution patterns over glaciers. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Investigating wind-driven Snow Redistribution Processes over an Alpine Glacier with high-resolution Terrestrial Laser Scans and Large-eddy Simulations

Author

Voordendag, Annelies, Goger, Brigitta, Prinz, Rainer, Sauter, Tobias, Mölg, Thomas, Saigger, Manuel, and Kaser, Georg

Abstract

Wind-driven snow redistribution affects the glacier mass balance by eroding or depositing mass from or to different parts of the glacier’s surface. High-resolution observations are used to test the ability of large eddy simulations as a tool for distributed mass balance modeling. We present a case study of observed and simulated snow redistribution over Hintereisferner glacier (Ötztal Alps, Austria) between 6 and 9 February 2021. Observations consist of three high-resolution Digital Elevation Models (∆x=1 m) derived from terrestrial laser scans taken shortly before, directly after, and 15 hours after snowfall. The scans are complemented by data sets from three onsite weather stations. After the snow fall event the snowpack decreased by 0.08 m on average over the glacier and typical snow redistribution patterns were observed. The decrease of the snow depth is to be attributed to both post-snowfall compaction and redistribution of snow. Simulations were performed with the WRF model at ∆x=48 m with a newly implemented snow drift module. The spatial patterns of the simulated snow redistribution agree well with the observed generalized patterns. Snow redistribution contributed -0.026 m to the surface elevation decrease over the glacier surface on 8 Feb, resulting in a mass loss of -3.9 kg m−2, which is in the same order of magnitude as the observations. With the single case study we cannot yet extrapolate to the impact of post-snowfall events on the seasonal glacier mass balance, but the study shows that the snow drift module in WRF is a powerful tool to improve knowledge on snow redistribution over glaciers and that the model setup can be applied to other mountain glaciers., EGUsphere

Published
2023
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10. Is it north or west Foehn? : A Lagrangian analysis of PIANO IOP 1

Author

Saigger, Manuel and Saigger, Manuel

Abstract

A case study of a foehn event in the Inn Valley near Innsbruck, Austria, is in- vestigated that occurred on 29 October 2017 in the framework of the first Inten- sive Observation Period (IOP) of the Penetration and Interruption of Alpine Foehn (PIANO) field campaign. Accompanied with northwesterly crest-level flow, foehn broke through at the valley floor as strong westerly winds in the moring and was terminated in the afternoon by a cold front arriving from the north. The differ- ence between local and large-scale wind direction rises the question of whether the event should be classified as north or west foehn – a question that has not been convincingly answered in the past for similar events based on Eulerian approaches. Hence, the goal of this study is to assess the air mass origin and the mechanisms of foehn penetration to the valley floor based on a Lagrangian perspective. For this purpose a mesoscale simulation with WRF and backward trajectory analysis with LAGRANTO are conducted. The trajectory analysis shows that the major part of the air mass arriving at Innsbruck originates six hours earlier over eastern France, crosses the two mountain ranges of the Vosges and the Black Forest and finally impinges on the Alps near Lake Constance and the Rhine Valley. Orographic precipitation over the mountains leads to a net diabatic heating of about 2.5 K and to a moisture loss of about 1 g kg −1 along the trajectories. A secondary air stream originates further south over the Swiss Plateau and contributes with about 10 to 25 % to the foehn air in Innsbruck. Corresponding trajectories are initially nearly parallel to the northern Alpine rim and get lifted above crest level in the same region as the main trajectory branch. Air parcels within this branch experience a net diabatic heating of about 2 K, and, in contrast to the ones of the main branch, an overall moisture uptake due to evaporation of precipitation formed above this air mass. Penetration into the Inn Valley main, by Manuel Saigger, Masterarbeit University of Innsbruck 2021

Published
2021

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