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FS 26.108

Weather and Climate in the Alps

Session status: Accepted

Content last updated: 2026-04-16 00:06:27

Online available since: 2025-12-16 21:41:02

Details

Full Title
Weather and Climate in the Alps - past, present, future
Scheduled
TBA
TBA
Chair
Lehner, Manuela
Co-chair(s)
Ban, Nikolina; Mayr, Georg; and Gohm, Alexander
Thematic Focus
Atmosphere, Climate
Keywords
Weather, Climate, Atmosphere

Abstract/Description

Mountains are playing a major role in shaping the weather and climate of the world. They are among the most sensitive ecosystems to climate change and are experiencing more rapid changes in temperature than environments at lower elevations. The complex topography is a major limiting factor in gaining a deeper understanding of processes and extreme events often associated with mountainous regions. Recent advances in measurement techniques and modelling over the European Alps are, however, enabling progress in our understanding. The proposed session focuses on Alpine weather and climate from past, present, and future, with an emphasis on atmospheric processes and climate change.

The session invites studies using high-resolution observations, reanalyses, numerical weather prediction, climate modelling, and regional downscaling to assess present-day Alpine weather and climate and its future changes. Contributions focusing on process understanding of mountain meteorology, land-atmosphere interactions, and the influence of complex topography on regional climate are particularly encouraged. The session also invites studies of trends in temperature, precipitation, circulation patterns, and extreme weather in the Alpine region.

By linking past, present, and future perspectives, this session aims to advance understanding of the mechanisms governing Alpine weather and climate and to support robust projections of climate change in complex terrain. The session provides a place to discuss recent methodological advances and emerging challenges in mountain climate research.

Registered Abstracts

ID: 3.59

Seasonal and elevation-dependent differences in temperature trends in the Tyrolean Alps (Austria): An assessment based on station observations

Erwin Rottler
Bertazza, Elena; Wagner, Franz; Meissl, Gertraud; Schellander-Gorgas, Theresa; Schöber, Johannes; Strasser, Ulrich

Abstract/Description

In this study, we aim to quantify the magnitude and significance of temperature trends on the sub-seasonal scale across elevations by collecting, processing and analyzing daily as well as hourly observational data from a dense network of climate stations located in the Tyrolean Alps (Austria). Our analysis reveals a 2.46°C rise in temperature for the 60-year period 1964–2023 and an increasing sub-seasonal variability of trends when shortening the investigated period from 60 to 30 years. We also find indications for a stronger warming at lower elevations, whereby this elevation-dependent signal can be traced back to strong differences in temperature trends in January with warming at low-elevation stations and a slight cooling at high elevations. The analysis of observation data to derive a picture of past climatic changes in mountain regions is of great importance to support our general process understanding and to complement the use of modeled data.

ID: 3.70

Large-scale weather and climate, local-scale impacts – bridging the gap with statistics

Michael Matiu
Crespi, Alice; Toldo, Francesco; Bozzoli, Michele; Bertoldi, Giacomo; Strasser, Ulrich; Majone, Bruno

Abstract/Description

Quantitative climate information is paramount for good decision-making. However, its usage in complex mountain terrain is often challenging because of the scale mismatch between provided meteorological variables and needs of input models. Sometimes, this scale gap is overcome using statistical methods. Here we explore different topics related to mostly statistical downscaling and bias adjustment, for example why we could, why we should, or maybe should not do it.

1) Using in-situ observations of snow depth and snowfall, we examine spatial and temporal variability. We show that even variables with high spatial and interannual variability like snow can share similar characteristics under long-term climate forcing.

2) We assess the role of multivariate bias adjustment and downscaling techniques with an ensemble of climate models to drive hydrological models that simulate snow water equivalent and runoff. This highlights the benefits and pitfalls of statistical post-processing of climate model output.

3) We present a novel downscaling technique based on principal components analysis that is able to merge information from different sources that are not in temporal synchrony. The contrasting results for temperature and precipitation should make us cautious when applying statistical methods that do not align with the processes resolved in climate models.

Consequently, we present conclusions from statistical analyses of climate variables and some statistical tools applied in post-processing of climate projections or (seasonal) weather forecasts, which are helpful to derive more meaningful and accurate climate and weather information for society. One such example of how these approaches can be used to create useful information is the Frame3S project that aims to provide seasonal forecasts of snow cover for the Tyrol-SouthTyrol-Trentino region.

ID: 3.111

Long-term Development of Avalanche Hazard Levels in the Austrian Alps

Philipp Maier
Jutz, Mira; Formayer, Herbert

Abstract/Description

Anthropogenic climate change strongly affects the Alpine water cycle. Shifts in the timing, intensity and spatial distribution of precipitation and increasing winter temperatures alter the frequency and timing of snowfall and snowmelt, as well as the structure of the snowpack. As a result, avalanche risk and the regionally assessed avalanche hazard levels are expected to change under ongoing climate change.

In this study, we present novel climatologies for avalanche hazard levels in the Austrian Alps covering the period of 1950 – 2025. These climatologies are based on the back-extension of a consistent multi-year observational dataset of avalanche hazard levels aggregated from regional avalanche hazard assessments. Individual mountain ranges are clustered into units that exhibit similar avalanche hazard responses to different types of weather patterns. These response units are then used to train a machine-learning algorithm to predict avalanche hazard levels based on pattern recognition and circulation analogues from meteorological ERA5 reanalysis data. Applying the algorithm to the full ERA5 dataset yields a reconstruction of past avalanche hazard levels, which are validated against long-term observations from Tyrol. The resulting climatologies reveal interannual and decadal variability as well as the possible influence of anthropogenic climate change on avalanche hazard over the past 75 years.

When applied to the latest generation of regional climate projections, the trained algorithm will provide new insights into how future climate change may further affect avalanche hazard in the Austrian Alps.

ID: 3.126

Structure of the convective mountain boundary layer over the European Alps from large-eddy simulations

Juerg Schmidli

Abstract/Description

The atmospheric boundary layer (ABL) over mountainous regions, such as the European Alps, plays a key role in controlling surface–atmosphere exchange processes, with direct implications for mountain weather, air quality, and climate. Owing to strong topographic heterogeneity, the Alpine boundary layer exhibits a wide range of interacting motions, spanning small-scale turbulence and coherent thermals, as well as thermally driven slope and valley circulations. Despite recent advances in high-resolution modelling, the three-dimensional structure of these flows, their evolution and role in vertical exchange processes remain insufficiently understood.

In this study, we investigate the structure of the convective Alpine boundary layer using the ICON model in large-eddy simulation (LES) mode. Real-case simulations are performed at horizontal grid spacings down to 65 m using a nested-domain configuration over highly complex Alpine terrain. A brief evaluation against observations from the TEAMx field campaign is presented to demonstrate the realism of the simulated boundary-layer structure. The main focus of the analysis is on the spatial organization, persistence, and diurnal evolution of the resulting coherent structures. The simulations reveal that thermals preferentially form at distinct locations tied to topography and surface forcing, exhibiting a robust diurnal cycle. These coherent structures play a central role in mediating vertical exchange of heat and momentum between the surface and the free atmosphere, while their interaction with slope and valley flows modulates boundary-layer depth and ventilation efficiency.

By providing a detailed three-dimensional view of boundary-layer processes over the Alps, this work advances process understanding of Alpine meteorology and demonstrates the value of LES for studying surface–atmosphere exchange and transport in complex terrain. The insights gained may provide guidance for constraining the representation of exchange processes in weather and climate models applied to mountainous regions.

ID: 3.123

Temperature Biases in convection-permitting models in complex terrain: ongoing challenges

Isabella Kohlhauser
Medvedova, Alzbeta; Ban, Nikolina; Maraun, Douglas

Abstract/Description

In recent years, convection-permitting models have become a frequently used tool to study climate and climate change in regions with complex terrain. While convection-permitting models have been shown to add value for variables like wind and precipitation, temperature is rarely in the focus, despite being a key climate variable. In our research we evaluate the representation of minimum and maximum daily temperatures in the convection-permitting CORDEX-FPS Convection ensemble. Additionally, we compare the kilometer-scale, convection-permitting ensemble to its corresponding driving coarse-scale ensemble with grid spacings of 2.2-4 km and 12-15 km, respectively. We identify severe negative elevation-dependent biases ensemble at both resolutions, which become progressively worse at higher elevations. Further, both ensembles overestimate extremes like hot days and frost days, which is more pronounced in the convection-permitting ensemble. In our analysis, we found little to no added value of convection-permitting models in comparison to the convection-parameterizing regional climate models. This is underlined by the high spread across ensemble members which is present in both ensembles. Our results highlight that even at the convection-permitting scale, model tuning and adapting parameterizations remains crucial.

ID: 3.165

Troposphere to stratosphere transport over the Alps

Petr Šácha

Abstract/Description

The stratosphere-troposphere exchange couples the troposphere and the stratosphere and affects the chemical composition in the upper-troposphere/lower stratosphere region, which is important for the global radiative budget. This study combines high-resolution Weather Research and Forecasting model simulations of the Alpine region validated by observations during selected intensive observational periods of TEAMx and the Lagrangian particle dispersion model FLEXPART-WRF to investigate the transport of boundary layer emissions during the events of pronounced dynamical interaction between the orography and the flow. The Alpine orography was found to enhance transport and modify pathways through which emissions can penetrate the tropopause and the stratosphere region. This results from a non-trivial combination of convective updrafts, orographic lifting and mixing due to breaking orographic gravity waves near the surface and in the vicinity of the tropopause. Our study has important implications for climate model development in terms of parameterizing subgrid-scale orography effects and for our understanding of the transport of pollution in mountain regions and globally.

ID: 3.218

Warming on the edge: topographic controls on temperature trends in the Alps

Simon Zitzmann
Fersch, Benjamin; Kunstmann, Harald

Abstract/Description

Elevation-dependent warming (EDW) is a prominent feature of climate change in mountain regions, often leading to enhanced warming at higher altitudes. Understanding the mechanisms behind this pattern is essential for assessing climate impacts in the Alps. While processes such as snow-albedo feedbacks and the high climate sensitivity of cold environments are discussed in literature, the contribution of topographic controls beyond elevation has received less attention.

This study explores spatial variations in warming across the Alps with a particular focus on how terrain characteristics influence local warming trends. Long-term temperature observations from the HISTALP dataset are used to analyze relationships between temperature trends and topographic factors throughout the Greater Alpine Region.

For the period 1951–2010, warming trends range from 0.4 to 2.9 K per century across elevations. Higher-altitude locations generally experience stronger warming, yielding an EDW signal of 0.25 K km^-1 century^-1 for annual mean temperatures. Seasonal differences are evident: the strongest elevation dependence occurs in summer (0.34 K km^-1 century^-1), whereas winter warming peaks at mid-elevations between 250 and 1000 m. Slope orientation further modulates warming, with northeastern-orientated slopes showing more pronounced trends.

Ongoing work extends the analysis by incorporating additional terrain variables, such as topographic incision, and by applying the approach to the extensive high-density observational dataset EEAR-Clim.

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FS 26.108

Weather and Climate in the Alps

Details

Full Title

Scheduled

Chair

Co-chair(s)

Thematic Focus

Keywords

Abstract/Description

Registered Abstracts

Abstract/Description

Abstract/Description

Abstract/Description

Abstract/Description

Abstract/Description

Abstract/Description

Abstract/Description

Submitted Abstracts

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