Item: ON SNOW AND AVALANCHE CLIMATES IN THE SWISS ALPS
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Title: ON SNOW AND AVALANCHE CLIMATES IN THE SWISS ALPS
Proceedings: International Snow Science Workshop 2024, Tromsø, Norway
Authors:
- Jürg Schweizer [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
- Lydia Knappe [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
- Benjamin Reuter [ Météo-France, Direction des opérations pour la prévision, Toulouse, France ] [ Univ. Grenoble Alpes, Univ. de Toulouse, Météo-France, CNRS, CNRM, Centre d'Etudes de la Neige, Grenoble, France ]
- Stephanie Mayer [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
Date: 2024-09-23
Abstract: The snow and avalanche climate types maritime, transitional (or intermountain), and continental are well-established in North America, but rarely used in Europe and particularly not known for the Swiss Alps. While the Swiss climatology is well-established for snow precipitation, there is no classification of snow and avalanche climate types. Recent efforts have addressed the lack of consistent avalanche climatology for the European Alps by considering the occurrence of avalanche problem types, expanding beyond the standard snow climate classification based solely on weather variables. Simulated snow stratigraphy obtained with a numerical snow cover model allows taking into account not only meteorological data but also snowpack properties for classification. Following the approach established in North America, we analyzed the data from 128 automated weather stations, in total 2230 winter seasons, to derive the snow climate types maritime, transitional and continental. The snow climate in the Swiss Alps is primarily transitional (45%), with large parts having a strong maritime influence (34%), and a few regions with a continental influence (21%). There are distinct regional differences. On the northern slopes of the Alps, the snow climate is predominantly maritime, less so on the southern slopes. In between, the climate class is mainly transitional, and in some regions of the Engadine and the Valais, the snow climate is to a good part continental. To expand the classification of the snow climates, the snow stratigraphy was analyzed with regard to the avalanche problem types and the frequency of four classes of grain types, notably persistent grain types and melt forms. While in the maritime snow climate we found many melt form layers and few persistent grains, the snowpack classified as continental included primarily persistent grains and rarely showed melt forms. Considering the simulated avalanche problem types suggested that the snowpack in regions with a transitional snow climate is more avalanche-prone than in the maritime and continental snow climates. These findings manifest the large variations seen in snow and avalanche climates across the Swiss Alps. Establishing a closer link between snow climates in the Swiss Alps and avalanche characteristics holds promise for avalanche forecasting, avalanche training and accident analysis.
Object ID: ISSW2024_P1.21.pdf
Language of Article: English
Presenter(s): Jürg Schweizer
Keywords: snow climate, avalanche climate, avalanche formation, snow stratigraphy, avalanche problem type
Page Number(s): 198 - 203
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