Transport of dust to high northern latitudes in a Martian polar warming

Abstract

The transport of dust to high northern latitudes in a Martian polar warming (and global dust storm) is investigated. General considerations of the dynamics of such an atmospheric warming indicate that transport of “tracers” such as dust to polar latitudes should take place, regardless of the specifie dynamical mechanism involved. Attention is focused upon a planetary wave induced polar warming, with a simplified transport model employed in conjunction with a beta‐plane dynamical model to simulate the transport of dust during a warming event. Numerical experiments are performed to examine the influence of different warming dynamics and to assess the sensitivity of the transport to the initial (that existing in the early stages of a global dust storm) dust distribution. Several simulations incorporating sedimentation are carried out, allowing examination of dust deposition at polar latitudes. The results of the numerical simulations indicate that substantial amounts of dust could be transported and deposited at high northern latitudes (extending to the pole) in a polar‐warming event. For a planetary wave warming the net transport is not very sensitive to the initial dust distribution (or to the details of the dynamics), as horizontal diffusive mixing plays a dominant role. Without such mixing (as might be the case if the dynamics does not involve planetary waves) the net transport is much more dependent on the initial state, with relatively elevated dust distributions favoring enhanced poleward transport. The potential for the transport of water is also examined, through several simulations in which condensation is neglected. These indicate that large amounts of water could be transported to the north polar region in a warming, given that substantial condensation and precipitation do not take place in subpolar regions. The warmth of the Martian atmosphere during global dust storms makes the latter plausible. The implications and significance of the transport of dust, as well as water, to high northern latitudes in global dust storm/polar warming events are discussed, in the context of the Mars climate system and the polar layered terrains.