How long could volcanic plumes persist in the Venus atmosphere?

Resolving the ambiguity surrounding current Venusian volcanism is a primary objective for upcoming missions like EnVision and VERITAS. This study uses the Venus Planetary Climate Model to simulate the dispersal and detectability of volcanic plumes containing water vapour (H2O), hydrogen chloride (HCl), carbon monoxide (CO), and carbonyl sulphide (OCS) within a three-dimensional atmospheric environment. We model localised gas enhancements at altitudes probed by nightside spectral windows (8.62, 20.91, and 35.45 km above surface). Results indicate that plumes persist longest in the deep atmosphere (8.62 km) at equatorial latitudes, where H2O enhancements remain distinguishable from low background variability for up to 100 hours, forming distinct downstream streaks. In contrast, at 35 km, high intrinsic variability in chemically active species (CO and OCS) driven by atmospheric dynamics obscures plume signatures and chemically inert species disperse within 0.5-2 Earth days. Plumes at high latitudes disperse more rapidly than at low latitudes at all altitudes. We perform sensitivity tests with trace gas increases of 50%, 40%, 30%, 20%, 10%, and 3% above baseline and plume injection times of 6, 12, 28, 38, and 126 hours at all three altitudes and two latitudes. We conclude that observing inert gases, in particular H2O, at low altitudes and latitudes offers the best opportunity for successful plume detection.