Henning Lowe (SLF) inspects a 2.60m snow pit on the morning of day one.
Snow is a complex material. Initially made of individual snowflakes, it rapidly forms one huge, layered and interconnected ice structure as the flakes bond together upon landing. The long limbs of the crystals mean that the resulting structure consists as much of air as it does ice.
This property makes snow into a porous material, allowing water vapor to flow around it. These structures and flows form the basis of snow science. Snow scientists use these principles to study mountain avalanches, hydrology, polar ecology and climate; once a year grad students from these fields gather for the Winter Snow Science School.
Funded by the Finnish Meteorological Institute, the Swiss Avalanche Research Institute and the French Weather Service, the week long school brings twenty-four grad students into the mountains for a crash course on measurement, modeling and remote sensing of snow. This year the school was based out of the University of Grenoble’s 2100m high research facility at Col du Lautaret in the French alps.
Zac Provant (U. Oregon) records the temperature profile in a snow pit
Most of the course is based in the field, split into an independent project (two days) or practical instruction from lecturers (two mornings). The rest of the week was filled with lectures and data-analysis.
On the first morning of the school we were in the field digging snow pits and describing what we found. Tuesday morning featured rotating bases run by the school’s lecturers. Each base had its own snow measurement and associated instruments: snow surface area with infrared reflectance; snow density and hardness with the Swiss ramsonde and the snow micropenetrometer (SMP); snow water equivalent measurement with density cutters and a total-SWE tube; density measurements with capacitance based instruments like a Denoth-meter; traditional profiling with grain-card and hand-lens; and a theoretical base calculating the specific surface area of different grain-like shapes.
On Wednesday and Thursday we spent all day in the field, first at a forested site and then at a more exposed site. Split into groups of four, each team was given a different investigation to carry out. Our task was to characterize the snow structure at both sites and compare it with the output of the French met-office model, CROCUS.
My team about to fill in our pit on the final field day.
Anna Karpova (SLF) weighing a snow sample in cold conditions
On the first day we experienced persistent falling and blowing snow, which meant that we had to periodically re-dig our pit and clean its wall. Our approach was to work fast and use all the methods listed in the previous paragraph, which we succeeded in doing (and also took some infrared photographs). Fortunately the second day had clear skies and we were in the sun by lunchtime. Because we worked more quickly as a team having practiced the day before, the mood was much more relaxed and we finished early.
After each field day we were given one or two lectures before dinner. Topics included: Arctic snow; the IPCC special report on Oceans and Cryosphere; snow microphysics; mountain snow in a changing climate; optical and microwave remote sensing; and snow-forest interactions.
Somebody has to sit and write down all the measurements, even when it’s cold and snowing.
Photo: Marie Dumont
On Friday we spent the day cleaning and analysing the data we’d collected on Wednesday and Thursday, and then presenting our results to the rest of the school. In addition to our model-comparison project, other projects focused on horizontal variability of key snow parameters and uncovering the history of the pit before comparison to weather data. We were finished by 3pm, in time for a group trip to the local spa - a very European experience. Then, suitably recovered after a tough week of information cramming and snow pit digging, we had a celebratory final night dinner.
From my perspective the school was a great success this year; I certainly enjoyed it and learned a lot. It was expertly planned and run by Marie Dumont and Neige Callone, and taught by Samuel Morin, Fabian Wolfsperger, Michaela Teich, Anna Kontu, Henning Lowe and Alex Langlois.