Transport and mixing of pollutants in a narrow alpine valley
Résumé
Atmospheric dynamics in narrow valleys often lead to the formation of bottom and capping inversion layers, whose features depend upon the geometry and the soil characteristics of the topography. The altitude and thickness of such stable layers evolve during a diurnal cycle under the effect of solar radiation. We conducted a numerical study of the processes leading to the formation and destruction of such inversion layers in a narrow alpine valley, using the ARPS 4.5.1 code. We therefore shall present considerations on the balance between the solar radiation incoming, the ground response and both the dynamic and static energies of the atmosphere. We will focus onto the interaction between soil fluxes and stable layers, enhancing the specific time constants of the valley . We shall also present a numerical method to evaluate the diffusive mixing in a stable atmosphere.