A Microphysics Model of Multicomponent Venus' Clouds With a High-Accuracy Condensation Scheme

Accurate modeling of the Venusian cloud structure remains challenging due to its complex microphysical properties. Condensation primarily determines the cloud particle size distribution within the various cloud layers. However, existing Venus microphysics models mainly use a full-stationary bin scheme, which may be prone to numerical diffusion during condensation. To address this, we developed a new microphysics model, the Simulator of Particle Evolution, Composition, and Kinetics (SPECK), which incorporates a moving-center bin scheme designed to minimize numerical diffusion. Furthermore, SPECK can accommodate any number of size distributions with multiple components, enabling versatile applications for more complex cloud systems. The 0-D simulations demonstrated that this microphysics framework is a reliable tool for modeling cloud microphysics under Venusian atmospheric conditions, particularly in capturing condensation and evaporation processes. We further validated SPECK against recent Venus microphysics models in 1-D simulations. The moving-center scheme is shown to exhibit less numerical diffusion compared to an existing model based on a full-stationary bin scheme, allowing for more accurate calculations of microphysical processes. Furthermore, SPECK reproduces the cloud structure observed by the Pioneer Venus Large Probe, using the same computational settings adopted in the latest microphysical model study. Thanks to the suppressed numerical diffusion, SPECK achieves high accuracy at half the typical resolution while reducing computational time sixfold, making it a promising tool for future 3-D modeling. This microphysics framework will be useful for the upcoming EnVision mission and is applicable to other planetary atmospheres, including those of Mars, Titan, gas giants, and exoplanets.