Comparison of a spectral microphysics and a two-moment cloud scheme: Numerical simulation of a radiation fog event

The spectral microphysics cloud scheme MiFog and the two-moment cloud scheme PaFog are implemented in a single-column model of the atmospheric boundary layer for the numerical simulation of a radiation fog event. Results of numerical sensitivity studies are presented where the influence of cloudiness on the evolution of the fog has been investigated. It is shown that the appearance of cloudiness in the morning hours triggers an efficient dissolution of the fog. During situations with weak turbulence, quasi-periodic oscillations of the liquid water content occur in the MiFog simulations. It turns out that these fluctuations are caused by the direct interaction of diffusional droplet growth and gravitational settling of the droplets. Comparison of the MiFog and the PaFog model runs reveals that most of the time PaFog is capable of simulating the bulk fog properties sufficiently well.

Automated summary

The study investigates the impact of cloudiness on the evolution of fog, revealing that the appearance of cloudiness in the morning triggers efficient dissipation of fog. In situations with weak turbulence, quasi-periodic oscillations of liquid water content occur in MiFog simulations. Comparison of MiFog and PaFog model runs shows that PaFog is capable of sufficiently simulating the overall fog properties most of the time.