Eruption column modelling of explosive volcanism on Venus

TL;DR

This study investigates explosive volcanism on Venus by applying the Earth-derived eruption-column model FPLUME to a realistic Venus atmosphere, including temperature-dependent heat capacity and super-rotation wind shear. It demonstrates that typical plumes reach about 15 km, but under favorable vent conditions can ascend into higher tropospheric or cloud-base altitudes, though stability remains constrained and only a small fraction reach 45 km. The sensitivity analysis shows plume height and stability are strongly modulated by volatile content and composition, pyroclast heat capacity, latitude, and emission altitude, with high-latitude and high-altitude vents more favorable for upper-atmosphere transport. These findings inform interpretation of upcoming Venus missions (e.g., EnVision VenSpec channels) and help constrain the climatic and atmospheric implications of contemporary Venus volcanism.

Abstract

Volcanism on Venus has never been directly observed, but several measurements indicate present-day activity. Volcanism could potentially play a role in climatic processes on Venus, especially in the sulfur cycle like on Earth. Observation of volcanic activity is the primary objective of future Venus spacecraft. However, there are many unknowns regarding its Venusian characteristics, like the condition at the vent, the volatile content and composition. Past modelling efforts have only studied explosive volcanic plume propagation over a limited range of flow parameters at the vent and in an idealised Venus atmospheric configuration. We propose to use the 1D FPLUME volcanic plume model in a realistic Venusian environment. In similar Venusian conditions, the height of the plume is consistent with past modelling. The present study shows that explosive volcanism would preferably reach 15 km of altitude. Under certain conditions, plumes are able to reach the VenSpec-H tropospheric altitude range of observations and even the 45 km cloud floor. For the first time, the impact of wind was quantified, and the super-rotating winds have a substantial impact by plume-bending of reducing the height of plumes. Contrary to the Earth, the atmospheric heat capacity depends greatly on temperature, and will disadvantage lower plumes and allow larger plumes to propagate at higher altitudes. The high latitude atmospheric environment, due to the thermal profile and weaker winds, is favorable to plumes reaching higher altitudes.

Figures (13)

• Figure 1: Vertical profiles of the Venus atmospheric temperature (top) in K, zonal wind (middle) in m s$^{-1}$, and pressure (bottom) in bar, density (bottom) in kg/m$^3$ and for the Equator (solid lines) and 75$^{\circ}$ of latitude (dashed lines). The data comes from The Venus Climate Database.
• Figure 2: Maximum altitude reached by the plume with the FPLUME model in relation to the vent radius at the Equator for a constant atmospheric heat capacity of 835 J kg$^{-1}$ K$^{-1}$ and a pyroclast heat capacity of 920 J kg$^{-1}$ K$^{-1}$ and without wind shear.
• Figure 3: Plume neutral buoyancy altitude (left) and maximum altitude (b) in relation to the MFR, exit temperature and exit velocity at the Equator for a constant atmospheric heat capacity of 835 J kg$^{-1}$ K$^{-1}$ and a pyroclast heat capacity of 920 J kg$^{-1}$ K$^{-1}$ and without wind shear.
• Figure 4: Vertical profiles of the Venusian atmospheric specific enthalpy (KJ) for a constant heat capacity (blue) and following the expression in equation \ref{['eq1']} (orange).
• Figure 5: Plume neutral buoyancy altitude (a) and maximum altitude (b) in relation to the MFR, exit temperature and exit velocity at the Equator for an atmospheric heat capacity varying with temperature and a pyroclast heat capacity of 920 J kg$^{-1}$ K$^{-1}$ and without wind shear.