The importance of alpine blowing snow for cloud processes

Abstract. Numerical models are known to fail in reproducing the large gap that exists between measured ice nucleating particle and ice crystal number concentrations in alpine regions. Improvements have been made by adding different sources of secondary ice production mechanisms into the models. Blowing snow has been identified as an additional possible source of ice particles. Driven by this assumption, we investigate the effect of blowing snow particles using the numerical model CRYOWRF, in which a new saltation scheme has been implemented to better represent the boundary conditions necessary for the blowing snow equations. First, ice crystal number concentrations are compared with measured data from Jungfraujoch, in the Swiss Alps, showing the importance of secondary ice production, blowing snow and microphysics scheme. Then, erosion and deposition patterns are also analyzed, as well as the influence of blowing snow on precipitation. It is shown that our implementation of blowing snow dynamics improves significantly the match between observed and simulated cloud particles.