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Test site in Davos Laret

The test site on the Weissfluhjoch above Davos, which is well-known worldwide, has demonstrated the value of long-term snow measurement series. The measuring site in Davos Laret that entered service in the winter of 2016/2017 complements the Weissfluhjoch facility by focusing on snow measurements in a new, especially climate-sensitive altitude zone (approximately 1500 m). Another benefit it offers scientists is the ability to compare the measurements performed in the field with data collected by satellites, and thus to evaluate the accuracy of snow measurements from space. Neither the Weissfluhjoch test site nor the Flüelastrasse facility is a suitable location for such comparative measurements.

Among the parameters being investigated in the outdoor lab in Laret is the amount of water that exists in the form of snow. Given that millions of people depend on the reservoir of snow deposited in the mountains for their water supply, this is a critical variable. Information concerning the water content is also useful in the hydropower industry and for triggering flood alerts.

Versuchsfeld Laret

Test site in Laret with a radiometer mounted on a lattice tower. Photo: Mike Schwank, WSL

Two lattice towers, one ten and the other six metres tall, have been erected on the 50 x 50 m test site in Laret. Each of the towers accommodates one measuring instrument. The first is a scatterometer, a device that emits microwave signals and interprets the reflected signals to calculate the snow's properties. The second instrument – a microwave radiometer – measures the energy naturally emitted by the snow. Among other outcomes, the data are used to produce a three-dimensional image of the snowpack as a basis for calculating the quantity of water it contains.

Instruments similar to those installed at the test site have been orbiting the Earth on board satellites, and measuring the snowpack remotely, for years. The data being collected at the test site in Laret serve the purpose of developing scientists' understanding of these measurements in the context of the Alpine terrain. For this reason the European Space Agency (ESA) is involved in the project as well.

Three further measuring stations (between 2.5 and 6 metres tall) have been erected at the site for collecting snow, weather and climate data in connection with other projects. In the medium to long term, the SLF will be using the site for additional snow and climate measurements as well.