Impacts of Dry Deposition Processes With Resolved Dust Particle Sizes on Simulating the Martian Dust

Mars, characterized as a “desert” planet with little water vapor, primarily relies on dry deposition for dust removal. Although these processes include gravitational sedimentation, turbulent transfer, Brownian diffusion, impaction, interception, and rebound, most current models consider only gravitational sedimentation. To have a more comprehensive understanding of the effects of Martian dust removal processes, a physics-based scheme of dry deposition processes with resolved dust particle sizes is implemented in the Mars Weather Research and Forecasting (MarsWRF) model. Results show that the size-resolved dry deposition scheme significantly increases the dry deposition velocity, with the maximum difference (over 0.024 m/s) occurring at 0.884 μm size bin. This enhanced removal efficiency leads to an increase of 0.4 μm in the effective radius of airborne dust throughout the year and a reduction of approximately 0.09 in dust opacity, particularly in the northern high latitudes during autumn and winter, compared to the simulation that only considers a size-resolved gravitational sedimentation scheme. The overestimation of low-level atmospheric temperature in the mid-to-low latitudes, excluding near-surface regions between $20°$ and $60°$N, during $L_s=230-250°$ (considered as peak-dust phase) is partially corrected, with a correction of up to 1 K compared to the single-particle size simulation and up to 5 K compared to the size-resolved sedimentation-only simulation, bringing it closer to MCS observations. Additionally, the size-resolved dry deposition simulation reduces the condensation rate of atmospheric CO₂ and the thickness of the northern CO₂ ice cap, aligning better with Viking Lander observations during northern winter and spring than the size-resolved sedimentation-only simulation.