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.

MarsWRF, the general circulation model of Mars, is one of the most commonly used models to study the dust cycle in the Martian atmosphere. It has been widely used to study the mechanisms of dust storms and their effects on the Martian atmosphere. To better understand the ability of MarsWRF to simulate the dust cycle on Mars, this study assesses the current dust lifting schemes in the model, specifically the convective lifting and wind stress schemes. It is found that, by tuning lifting efficiency, the model with the convective lifting scheme can generally reproduce the seasonal variation of the mid-level atmospheric temperature (T15) but cannot reproduce the observed spatial distribution of dust devils, which exhibits non-homogeneous (uniform) distribution in the northern (southern) hemisphere. The model with the wind stress lifting scheme can generally capture the observed magnitude of T15 and column dust optical depth (CDOD) with properly tuned lifting efficiency and threshold drag velocity. There is a discrepancy in the assessment of modeling seasonal variations of dust with T15 and CDOD, which may be partly due to the observational uncertainties related to T15 and CDOD and the empirical modeling methods of Martian dust optical properties and radiative effect. For the spatial distribution of dust, there are significant simulation biases regardless of the tuning, which may be caused by the biases in the dust lifting process and large-scale atmospheric circulation. The analysis highlights that dust lifting schemes need further improvement to better represent the dust cycle and their impacts on Mars.