Coupling a snowmelt model with a snowdrift model for the study of snow distribution on roofs

A coupled model resulting from the coupling of a sub-snowmelt model and a sub-snowdrift model has been proposed to simulate the snow distribution on roofs. Firstly, based on energy and mass balance, a multi-layer roof snowmelt model, in which the snow accumulation, compaction, melting, and refreezing processes can be considered, was developed in this paper. Then, the snowmelt model was coupled to a quasi-steady snowdrift model to predict the snow distribution on building roofs. With the coupled model, the convection and turbulent diffusion of snow particles caused by wind can be predicted through the sub-snowdrift model by Computational fluid dynamics (CFD) simulations. On the other hand, the variations of snow properties, especially the threshold friction velocity, are simulated by the sub-snowmelt model based on mass and energy balance. Finally, three models (the coupled model, the snowmelt model used individually and the snowdrift model used individually) were applied to simulate the snow distribution on a flat roof, respectively. The characteristics of snow distribution simulated by the coupled model was compared with those simulated when the snowdrift model or the snowmelt model was applied individually.