Dynamics-regulated cloud distribution on Venus

Venus is covered by dense sulfuric acid clouds at around 47-70 km altitudes, which have great impact on the global temperature and climate change by controlling its energy balance. The cloud mass and opacity are observed to increase with decreasing altitude, and the shape of the vertical profiles is characterized by a three-step staircase pattern. In particular, the lower clouds possess an exceptionally high mass density. Model analysis indicates that the formation of the middle and lower clouds is primarily governed by atmospheric dynamics, including eddy diffusion and vertical wind transport. Nevertheless, substantial uncertainties remain in our understanding of these processes. A key limitation arises from the scarcity of observations within the cloud deck, which has led to a wide range of empirically adopted cloud eddy-diffusion coefficients in existing models. Furthermore, most previous studies investigating vertical wind transport acquire the wind velocity profiles under the assumption of conserved vertical mass flux in the background atmosphere, which do not include the effects of divergent and convergent of large-scale atmospheric circulation on the vertical distribution of trace gases. In this work, we develop a one-dimensional triple-modal cloud model with vertical wind velocity profiles from recent general circulation model simulations. The derived cloud mass loading shows good agreements with observations. Through sensitivity experiments, we investigate the impact of cloud diffusivity and vertical winds on Venusian cloud structures. The results also demonstrate that these dynamical effects vary substantially across different latitudes.