Meteorological observations, snow volume change and insulation experiment data at Craftsbury Outdoors Center, Vermont in 2018

Climate change, including warmer winter temperatures, a shortened snowfall season, and more rain-on-snow events, threatens nordic skiing as a sport. In response, over-summer snow storage, attempted primarily using wood chips as a covering material, has been successfully employed as a climate change adaptation strategy by high-elevation and/or high-latitude ski centers in Europe and Canada. Such storage has never been attempted at a site with both a low altitude and latitude, and few studies have quantified snowmelt repeatedly through the summer. Such data, along with tests of different cover strategies, are prerequisites to optimizing snow storage strategies. Here, we assess the melt rates of two wood-chip covered snow piles (each ~200 m3) emplaced during spring 2018 in Craftsbury, Vermont (45o N and 360 m asl) to develop an optimized snow storage strategy. In 2019, we tested that strategy on a much larger, 9300 m3 pile. In 2018, we continually logged air-to-snow temperature gradients under different cover layers including rigid foam, open cell foam, and wood chips both with and without an underlying insulating blanket and an overlying reflective cover. We also measured ground temperatures to a meter depth both under and adjacent to the snow piles and used a snow tube to measure snow density. During both years, we monitored volume change over the melt season using terrestrial laser scanning. In 2018, snow volume loss ranged from -0.29 to -2.81 m3 day-1 with highest rates in mid-summer and lowest rates in the fall; mean melt rates were 1.24 and 1.50 m3 day-1, 0.6 to 0.7 % of initial pile volume per day. Snow density did increase over time but most volume loss was the result of melting. Wet wood chips underlain by an insulating blanket and covered with a reflective sheet was the most effective cover combination for minimizing melt, likely because the surface reflected incoming shortwave radiation while the wet wood chips provided significant thermal mass, allowing much of the energy absorbed during the day to be lost by long-wave emission at night. The importance of pile surface area to volume ratio is demonstrated by the melt rates of the 9300 m3 pile emplaced in 2019 which lost only <0.16% of its initial volume per day between April and September, retaining 75% of the initial snow volume over summer. Together, these data demonstrate the feasibility of over-summer snow storage at mid-latitudes and low altitudes and suggest efficient cover strategies.