New satellite technology tested in the Schnalstal/Senales valley to measure the thermal conductivity of snow and monitor water resources
image: Measurements on the ground were made by eight groups, matching the route of the Cessna aircraft. The measurements were taken at intervals of a few meters. The temperature at altitude was around -15 °C with, at times, very strong wind. view more
Credit: Eurac Research | Maurizio Gretter
The first flight arrived in the valley around 7 a.m., the second around 1 p.m. During each flight the Cessna zigzagged over the area at an altitude of 5,000 meters for about 40 minutes. For the research team, having the same flight at different times of the day was critical. “Until now, to monitor snow we have used satellite images that measure direct properties such as depth and density,” explains Carlo Marin, a remote sensing engineer at Eurac Research. “Instead, this technique developed by University Milano Bicocca measures how the snow breathes, that is, the heat exchange between the snow and the air. From this information we can gauge properties such as density and type of snow. In the early morning flight, the temperature is cooler, and in the warmer hours of the day, the surface layer of snow is warmer due to higher temperatures and sunlight. The difference in temperature relates to how different types of snow exchange heat with their surroundings. In addition, the experimental sensor images promise very high resolution.”
As the small Cessna plane flew along 12 strips technically known as “transects”, 22 people were in place on the ground to measure the depth of the snow and its weight at three-meter intervals. And by doing so, were able to determine the snow density: the wetter being heavier, the lighter, powdery and finer. Some research teams were not far from lifts, but others had to reach remote spots, such as the Teufelsegg peak, in below the Weisskugel/Palla Bianca (3,738 m), by trekking for hours with skis, ski skins and backpacks loaded with equipment. One team was also accompanied by technicians carrying the same type of sensor as the one mounted on the plane to further corroborate the measurements from the ground.
In the coming months, the research team will cross-reference the measurement results and test whether the technology is mature enough to be installed on a satellite and become operational.
“In light of the climate crisis making water an increasingly scarce and valuable commodity, carefully calculating the presence of snow, especially at high altitudes, will become increasingly important in more accurately estimating the availability of water for the summer season and as such, give support to those who have to administer this resource,” concludes Marin.