Modeling studies of dust/gas non-thermal equilibrium in the Martian atmosphere

Abstract

We discuss and implement the physics of dust-gas non-equilibrium processes into 1-D radiative-convective and 3-D climate models to assess at what altitude dust and gas temperatures in the Martian atmosphere diverge and to what extent it affects the thermal structure, dynamics, and transport capabilities of the upper atmosphere. As found in an earlier paper by Goldenson et al. (2008), we find (using a different approach) that dust and gas temperatures diverge above 40 km as collisions between dust particles and gas molecules are too infrequent to equilibrate these two components. With our 1-D model we show that when dust-gas non-equilibrium physics is included, gas temperatures above 40 km cool and heating rates are reduced. The magnitude of the effect depends mostly on the size and abundance of the dust particles and is proportional to each. With our 3-D model we show that this physics is important mainly during times of intense dust lifting events such as local rocket storms, or regional or global storms when dust quickly penetrates to high altitudes and particle sizes can be somewhat larger at least initially. During such times upper atmosphere temperatures cool, wind systems are weakened, and vertical and meridional transport is diminished when compared to simulation assuming thermal equilibrium.