Hadley circulation drives material isolation and pole-to-pole teleconnection on Mars

Abstract

Global-scale circulation dominates material transport in planetary atmospheres, which is thought to account for large-scale compositional mixing on Earth and other planets. However, observations of the Martian atmosphere challenge this picture. The mixing ratios of dust and gas species (H2O, CO, Ar) show large planetary-scale inhomogeneities, yet the mechanism causing this has been difficult to define. Here we investigate particle transport in the Martian atmosphere using a Lagrangian tracking method based on reanalysis data. We find that the coherent structure of the single-cell Hadley circulation on Mars can produce a distinct material transport pattern. Dynamical barriers prevent material mixing between the inside and outside of the Hadley cell and allow pole-to-pole teleconnection. Dimensional analysis indicates this is caused by the combined effect of rapid planetary rotation and the thin atmosphere of Mars. The dominance of the mean circulation over the eddy transport gives rise to this unique transport regime, which is fundamentally distinct from those on Earth and Venus. This finding challenges the conventional view of material mixing from planetary-scale circulations, suggesting planetary atmospheric dynamics can confine materials and restrict redistribution. Single-cell Hadley circulation drives pole-to-pole connection on Mars but also inhibits material mixing between the cell’s interior and exterior, according to a study of the Martian atmosphere using Lagrangian particle tracking.