Potential of satellite data for avalanche forecasts

Improved avalanche forecasts thanks to data from satellites

Earth observation satellites have been in orbit for many years. They not only measure reflected sunlight, but also transmit radio waves and record the extent to which these waves bounce back off the surface of the Earth and snowpack. In view of its wish to investigate the potential benefits of these technologies to avalanche warning services, the European Space Agency ESA commissioned a consortium headed by the SLF to generate a feasibility study. The researchers were asked to identify critical information gaps and explore how these could be closed through satellite data.

Key parameters: avalanche activity and snow properties

In a first step, the consortium conducted interviews and a workshop to establish the existing needs of national and regional avalanche warning services as well as safety experts. In particular, these stakeholders wish to obtain information relating to the following questions: "Where have avalanches occurred?", "What is the condition of the snow cover surface?", and "How stable is the snowpack?" The individual target groups had widely diverging views, however, on the required data resolution and the geographic region that was to be covered.

Based on both the responses of the surveyed potential users and the available technology, the consortium defined a modular system. It brought together satellite-based and terrestrial radars for detecting avalanche events, and data captured by optical and radar satellites in order to characterise the snow surface properties.

Satellite data could close gaps

In the next step, the researchers examined whether this system provides a practicable solution. They installed a terrestrial radar on the Dorfberg near Davos and also analysed data for the same area retrieved from optical and radar-based satellites. A comparison of the space measurements with information captured conventionally – by web cameras, avalanche observations and automatic weather stations – showed that they had tremendous potential for use in the detection of avalanches over extensive areas in all weathers. The data could therefore significantly enhance avalanche warning capabilities. To date, avalanche forecasters base their warnings largely on weather models and data delivered by automatic weather stations and observers in the field. In many countries, however, there is a shortage of weather stations. In addition, poor weather and the danger of avalanches frequently hamper the activities of observers. Data from space could close these gaps in the future.

Costs currently too high

The feasibility study also revealed however, that relevant data is not yet sufficiently widely available, lacks temporal resolution and is very expensive. Given that the prospective users have limited resources in many cases, they cannot afford to use the data operationally at present. They remain nevertheless interested in this highly promising technology. Various new projects will accordingly continue to investigate the topic in future.