Operational implementation and evaluation of a blowing snow scheme for avalanche hazard forecasting

Vionnet, V. ; Guyomarc'h, G. ; Lafaysse, M. ; Naaim Bouvet, F. ; Giraud, G. ; Deliot, Y.

Type de document
Article de revue scientifique à comité de lecture
Langue
Anglais
Affiliation de l'auteur
METEO FRANCE CNRS UMR 3589 CNRM GRENOBLE FRA ; METEO FRANCE CNRS UMR 3589 CNRM GRENOBLE FRA ; METEO FRANCE CNRS UMR 3589 CNRM GRENOBLE FRA ; IRSTEA GRENOBLE UR ETGR FRA ; METEO FRANCE CNRS UMR 3589 CNRM GRENOBLE FRA ; METEO FRANCE CNRS UMR 3589 CNRM GRENOBLE FRA
Année
2018
Résumé / Abstract
In alpine terrain, blowing snow events strongly affect the local evolution of the avalanche danger and must be taken into account by avalanche hazard forecasters. This study presents the implementation and the evaluation of the blowing snow scheme Sytron into the operational chain for avalanche hazard forecasting (named S2M) used in the main French mountain ranges. S2M-Sytron provides information on blowing snow occurrence and intensity per 300-m elevation bands and aspects for several regions of the French mountains. The wind forcing is provided by the meteorological analysis system SAFRAN. S2M-Sytron was evaluated for winter 2015/16 at 11 automatic stations measuring wind speed and blowing snow fluxes in the French Alps. The system detects 55% of blowing snow days with less than 10% of false alarms. S2M-Sytron captures the occurrence of blowing snow events with and without concurrent snowfall. Improvements are obtained when considering an updated parameterization for the properties of falling snow which reduces the threshold velocity for freshly fallen snow. Using observed wind speed instead of SAFRAN wind speed to drive Sytron shows further improvements at stations where SAFRAN wind speed differs from the observations due to local topographic features. Overall, S2M-Sytron provides a regional blowing snow assessment but cannot fully reproduce the local intensity of blowing snow events.
Source
Cold Regions Science and Technology, vol. 147, p. 1 - 10

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