Martian dust devil statistics from high-resolution large-eddy simulations

Abstract

Dust devils are one of the key elements in the Martian atmospheric circulation. In order to examine their statistics, we conducted high-resolution (up to 5 m) and wide-domain (about 20 × 20 km2) large-eddy simulations of the Martian daytime convective layer. Large numbers of dust devils developed spontaneously in the simulations, which enabled us to represent a quantitative consideration of Martian dust devil frequency distributions. We clarify the distributions of size and intensity, a topic of debate, and conclude that the maximum vertical vorticity of an individual dust devil has an exponential distribution, while the radius and circulation have power law distributions. A grid refinement experiment shows that the rate parameter of the vorticity distribution and the exponent of the circulation distribution are robust. The mode of the size distribution depends on the resolution, and it is suggested that the mode is less than 5 m.