Verhalten abseits der Piste Avalanche accidents Wissenswertes über Lawinen Literatur Kernteam Lawinenausbildung Exceptional avalanche situations
Expedition Princess Elisabeth
Scientists investigating the polar regions are among those eager to draw on the SLF's snow science expertise and outstanding analytical methods. For around the past 10 years SLF scientists have regularly been invited to join international research expeditions, in particular to collect data concerning the snow microstructure. The first ever independent expedition undertaken by the SLF in East Antarctica took place in the 2016/17 Antarctic summer season in collaboration with the laboratory of cryospheric sciences affiliated to the higher education institution EPFL.
Climate change is triggering dramatic changes in the polar snow and ice masses. Most glaciers and ice sheets are melting and contributing to rising sea levels. In East Antarctica, in contrast, additional ice could be formed if the amount of precipitation increases, and if temperatures remain sufficiently low. In order to verify this change by way of measurements, the surface mass balance has to be monitored. From mid-December 2016, two scientists spent about two months at the Belgian research station Princess Elisabeth for this purpose. They installed two measuring stations to record weather data and the rates at which snow is wind-transported and drifted. Powered by wind and solar energy, these innovative stations are to remain in place throughout the year. They will therefore be able to measure, for the first time, the snow-transporting processes which take place during the Antarctic winter. In the course of their residence at the Princess Elisabeth station, the scientists used a laser scanner and drone photogrammetry to examine the snowpack before and after the snowfall periods, and a snow micropenetrometer (SMP) to determine the properties of the deposited snow layers.
Projecting the mass balance for East Antarctica
The researchers were fortunate with the weather. As a kind of Christmas present, approximately 10 cm of snow fell and was immediately followed by strong winds. They were able to demonstrate that within just a few days, the snow masses had been completely transformed into barchan dunes, a common crescent-shaped land form that develops perpendicular to the wind direction. This constituted a new discovery – barchans had previously been regarded as an exceptional form of polar snow deposit. Although not immediately recognisable as such, the dunes are clearly revealed by repeatedly measuring the snow surface.
Once the Antarctic winter has passed, the researchers will be returning to Princess Elisabeth to repeat their surface measurements and collect the data captured by the automated measuring stations. After analysing the data back in their warm offices, they will be able to estimate how much snow has been deposited in the course of a year, and to what extent the snow-transporting process has reduced the effects of the snowfall. The amount of snow being transported is reduced not only by wind erosion, but also and in particular because the snow particles return mass to atmosphere while airborne. Until now this sublimation process could be modelled only in a extremely simplified form. With the aid of the SLF measurements it should be possible to glean the impact of sublimation more accurately in future. The researchers will also be seeking to project the total mass balance for East Antarctica on the basis of the highly localised data. They are hoping ultimately to be able to better assess the role played by snow transport in the climate-related changes which are taking place in Antarctica.