SAFRAN-Crocus snow simulations in an unstable and windy climate

Abstract

SAFRAN and Crocus are simulation systems developed at the Centre d'Études de la Neige, the snow research department of Météo-France. SAFRAN analyzes weather parameters relevant to snow on the ground, and Crocus simulates the build-up of the snowpack. In this study, simulated snow depths and measured snow depths at three locations in Iceland were compared. The main study was performed for the Hveravellir weather station located 640 m a.s.l. in central Iceland. The results from three winters, 1994-97, were analyzed. In Iceland the "Alpine" version of the models systematically underestimated the snow depth and density of the snowpack. Corrections for the effect of wind on snow density and on precipitation measurements led to significant improvements in simulated snow depths. The simulations are sensitive to the threshold temperature between snow and rain. The remaining problems in simulating the snowpack are mainly related to transport of snow by wind, which is not accounted for in the models, and to some extent to melting and sublimation in strong winds.