Chemical Cycling in the Venusian Atmosphere: A Full Photochemical Model From the Surface to 110 km

Abstract

Abstract Venus is an exceptional natural experiment to test our understanding of atmospheric sulfur chemistry. Previous modeling efforts have focused on understanding either the middle or lower atmosphere. In this work, we performed the first full atmosphere analysis of the chemical transport processes on Venus from the surface to 110 km using a 1‐D diffusion model with photochemistry. We focused on the cycling of chemical species between the upper and lower atmospheres and interactions between distinct species groups including SO , CO + OCS, chlorides, NO , O , and S . We tested different eddy diffusivity profiles and investigated their influences on the vertical profiles of important species. We find that the assumed boundary conditions in previous models strongly impacted their simulation results. This has a particularly large effect for SO . We find the high SO abundance in the lower atmosphere is readily transported into the middle atmosphere, far exceeding observed values. This implies some yet unknown chemistry or process limiting SO mixing. We summarize outstanding questions raised by this work and note chemical reactions that should be the highest priority for future laboratory studies and ab initio calculations.