Impacts of dry deposition processes with resolved dust particle sizes on
simulating the Martian Dust
Abstract
Mars, characterized as a “desert” planet with little water vapor,
primarily relies on dry deposition processes for dust removal. Although
dry deposition processes include gravitational sedimentation, turbulent
transfer, Brownian diffusion, impaction, and interception, gravitational
sedimentation is considered the only way for dust removal in most
current models. To have a more comprehensive understanding of the
effects of Martian dust removal processes, a physics-based scheme of dry
deposition processes (e.g., turbulent transfer, Brownian diffusion,
impaction, and interception) with resolved dust particle sizes
representing the lifting dust size distribution is implemented in the
MarsWRF general circulation model in this study. The model results
reveal that the dry deposition velocity increases significantly with the
decrease in dust size, especially for small dust particles. This
enhancement in the removal efficiency of small particles leads to an
increase in the effective particle radius of airborne dust and a
decrease in dust opacity, particularly in the high latitudes of the
northern hemisphere during the period of high dust loading. In these
latitudes, the atmospheric temperature rises from the surface up to an
altitude of 55 km, with a peak temperature difference of about 3.8 K,
driven by dynamical warming from the strengthened descending branch of
the upper meridional circulation. In addition, the sublimation of CO2
surface ice in the high latitudes of the northern hemisphere is
increased, and the condensation of the gas phase is decreased.