Rapid Decay of Martian Global Dust Storms Driven by Small‐Scale Deposition Processes in the Lower Planetary Boundary Layer

Abstract As one of the iconic features on Mars, global dust storms (GDSs) often decay rapidly. However, general circulation models (GCMs) typically underestimate their decay rates, which is one of the major challenges in simulating the Martian atmosphere. Here, we evaluate the role of a recently implemented size‐resolved microphysical deposition scheme of dust particles in the MarsWRF model on GDS evolution. This scheme includes a series of microphysical processes, in addition to gravitational sedimentation, which facilitates the efficient removal of small dust particles. The model successfully reproduces the observed increase in effective particle radius during dust storms, along with their rapid decay. A radiative‐dynamic positive feedback loop is seen among solar insolation, atmospheric stability, dust lifting and dissipation, and atmospheric dynamics. These results highlight the role of microphysics in the development of planetary‐scale events on Mars, and underscore the need to include small‐scale processes in Mars GCMs.