Seasonal evolution of a ski slope under natural and artificial snow: detailed observations and modelling
Pierre Spandre1,2, Hugues François1, Emmanuel Thibert1, Samuel Morin2, and Emmanuelle George-Marcelpoil11Université Grenoble Alpes, Irstea, Grenoble 2Météo-France CNRS, CNRM-GAME UMR 3589, Centre d'Etudes de la Neige, Grenoble
Received: 12 Aug 2016 – Accepted for review: 02 Sep 2016 – Discussion started: 05 Sep 2016
Abstract. The production of Machine Made (MM) snow is now generalized in ski resorts and represents the most common adaptation method to mitigate the impacts of both the natural variability and projected changes of the climate on the snow conditions to guarantee suitable conditions for skiing. Most investigations of the impact of snow conditions on the economy of the ski industry under past, present or projected climate focus on the production of MM snow. So far, none of them accounted for the efficiency of the snowmaking process i.e. the actual MM snow mass that can be recovered from a given water mass used for snowmaking. The present study consisted in observations and interpolation on a 0.5 × 0.5 m grid of snow conditions (depth and mass) using a Differential GPS method and snow density coring, after single sessions of production (prior to MM snow spreading by grooming machines) and on the ski slope as opened to skiers, on a beginner trail in Les Deux Alpes ski resort (French Alps). A detailed physically based snowpack model accounting for grooming and snowmaking was used to address the seasonal evolution of the snowpack and compared to the observations. Our results show that approximately 30 % of the water mass can be recovered as MM snow within 10 m from the center of a MM snow pile after the production and 50 % within 20 m. The observations and simulations on the ski slope were relatively consistent with 60 % (±10 %) of the water mass used for snowmaking within the edge of the ski slope. We also addressed the losses due to thermodynamic effects resulting in less than 10 % of the total water mass in the present case. The main uncertainty pertains to the surface of observations: the surface of the ski slope opened to skiers changed along the season and objective uncertainties exist, in particular from man-made decisions. These results suggest that even in the ideal conditions for production a significant fraction of the water used for snowmaking can not be found as MM snow within the edge of the ski slope with most of the lost fraction of water due to site dependent characteristics (e.g. meteorological conditions, topography, human decisions).
Spandre, P., François, H., Thibert, E., Morin, S., and George-Marcelpoil, E.: Seasonal evolution of a ski slope under natural and artificial snow: detailed observations and modelling, The Cryosphere Discuss., doi:10.5194/tc-2016-194, in review, 2016.