Glaciers are a defining feature of mountain landscapes and, in some regions, an important freshwater and hydropower resource. As glaciers continue to shrink worldwide, improving our ability to predict their future evolution has become increasingly important. While incoming solar radiation is the primary driver of glacier melt, the exchange of energy between the glacier surface and the atmosphere can also contribute substantially to melt. Understanding and quantifying this exchange remains a major challenge because it is governed by atmospheric turbulence, a complex and highly variable process that is difficult to observe, understand, and represent in models.
During summer, alpine glaciers often develop their own local microclimate that is embedded within the larger-scale atmospheric conditions. While sun-warmed slopes surrounding a glacier heat the air and drive upslope flows, the cold glacier surface cools the adjacent air, causing it to flow downslope over the glacier. This glacier wind, known as a katabatic flow, strongly influences the exchange of heat, moisture, and momentum between the atmosphere and the ice. However, its structure is highly detailed and complex, varying in space and time and interacting with the glacier surface itself.
Silvretta Glacier above Klosters provides an ideal natural laboratory to investigate these processes. The glacier has been observed continuously since 1915 through mass-balance measurements, topographic surveys, and photogrammetric mapping, providing a unique long-term record of glacier change. Building on this foundation, we conducted two intensive field campaigns on the glacier: one in August–September 2024 and a second in June–July 2025. During these campaigns, we collected detailed micrometeorological observations, including air temperature, humidity, radiation, wind speed, and wind direction. To characterize turbulence directly, we measured three-dimensional wind velocities together with temperature and humidity at high sampling frequencies.
To better understand how glacier surface properties influence atmospheric exchange, we also documented the glacier surface using cameras and drones. Photographs from multiple perspectives were combined to create detailed three-dimensional models of the terrain surrounding the measurement sites. These models allow us to investigate how features such as melting snow, exposed ice, and crevasses affect surface roughness and thus turbulent exchange.
In addition, we included an innovative method to visualize atmospheric flow structures above the glacier. Large screens made of thin synthetic fabric were installed and observed with infrared cameras. As air with changing temperature moves across the screens, it alters their temperature, allowing otherwise invisible flow patterns to be captured and analysed at very high spatial resolution.
Although the study is still ongoing, several findings have already emerged. The meteorological observations provide a comprehensive overview of the weather conditions during the field campaigns and allow different flow regimes to be identified. Analysis of the glacier surface has revealed a decrease in aerodynamic roughness as the surface transitions from melting snow to bare ice. We also found that surface roughness depends on wind direction: airflow parallel to the glacier slope experiences lower roughness than airflow crossing the glacier. Preliminary analysis of the infrared observations demonstrates that the method is capable of resolving small-scale flow structures and turbulence as well as detailed changes in the vertical temperature stratification above the glacier.
These results, together with ongoing analyses, improve our understanding of glacier–atmosphere interactions and can help refine atmospheric and glacier models and may ultimately contribute to more reliable predictions of glacier melt in Switzerland, across the Alps, and in mountain regions worldwide.