Large-Eddy Simulations of Vertical Vortex Formation in the Terrestrial and Martian Convective Boundary Layers

Abstract

Large-eddy simulations (LES) of the Martian and terrestrial convective boundary layers (CBL) are performed to compare the physical characteristics of simulated convective vertical vortices to those of observed dust devils and vortices. Martian and terrestrial CBLs are outwardly found to have similar structures and turbulence statistics based on primary mechanisms for the transfer of energy from the insolated surface. Applying the heating effect of radiative flux divergence in the Martian atmosphere caused differences in atmospheric vertical profiles in the surface and mixed layers of Mars. In general, the Martian boundary layer is found to be roughly four times deeper than Earth’s, indicating that convection on Mars is more intense than that on Earth due to a lower atmospheric density. Performing fine-resolution simulations in quiescent atmospheres of the two planets, it is found that the general vorticity development in all cases is similar and that the Martian vorticity columns extend six times higher and are 10 times wider than those on Earth. The accuracy of the simulated vortices as compared with observed physical characteristics is discussed. This study is a necessary part of a larger effort for the Phoenix Mars mission and examines the possible formation and maintenance mechanisms for vertical vortices in the Martian convective boundary layer at the Phoenix lander site.