Characterizing Dust‐Radiation Feedback and Refining the Horizontal Resolution of the MarsWRF Model Down to 0.5 Degree

Abstract

On Mars, dust is lifted from the surface into the atmosphere by the winds and dust devils and is subsequently transported by atmospheric advection and global circulation over local, regional, and planetary scales. Global and mesoscale circulation models have simulation routines, or so-called parametrization schemes, that describe the physics of dust lifting, transport, and sedimentation, as well as the dust’s interaction with radiation. These model schemes have tunable parameters that directly control physical processes such as the amount of dust lifted from the surface into the atmosphere. This can be achieved through near-surface winds that are strong enough to lift dust from the surface or by convective vortices (“dust devils”) that Abstract In this study, three simulations by the Mars Weather Research and Forecasting Model are compared: two 10 Martian year (MY) 2° × 2° simulations with (i) fully radiatively active dust and (ii) a prescribed dust scenario, and a (iii) 1 MY 0.5° × 0.5° simulation with prescribed dust as in (ii). From comparing (i) and (ii), we found that the impact of dust-radiation feedback is individually different for any region. The most striking evidence are major dust lifting activities to the south of Chryse Planitia (S-CP) seen in (i) but not in (ii). By contrast, dust lifting and deposition on the southern slopes and inside the Hellas Basin are similar in both simulations. The latter, in turn, points toward a similar near-surface atmospheric circulation. In (iii), the total global amount of wind stress lifted dust is by a factor of ∼8 higher than in (ii), with S-CP being a major lifting region as in (i). Nonetheless, the surface dust lifting by wind stress in (iii) may be also reduced regionally, as seen at the peak of Elysium Mons because of its unique topography. The zonal mean circulation in (i) is generally of a comparable strength to that in (ii), with exceptions in global dust storm years, when it is clearly stronger in (i), in line with a dustier atmosphere. The differences in the zonal mean circulation between (ii) and (iii) are mostly at lower altitudes and may arise because of differences in the representation of the topography.