14 October 2026: Maureen Cohen

Speaker: Maureen Cohen (Open University)

Date: Wednesday 14 October 2026

Time: 14:00

Location: Physics 3.34

Waves or Volcanoes? Untangling Variability in the Venus Deep Atmosphere

Venus and Earth formed in the same neighbourhood of the protostellar disc and are nearly twins in size. Yet one has oceans and forests, while the other is a furnace wrapped in sulphuric acid clouds. Whether Venus was ever habitable, and for how long, bears directly on how common habitable worlds are. Many rocky exoplanets now being discovered follow Venus-like orbits near the inner edge of their star's habitable zone.

Geologists search for Venus' history in lava flows, tectonic features and surface emissivity. Atmospheric scientists search for it in isotope ratios and the sulphur in its cloud decks. Between their two domains lie 45 kilometres of poorly understood deep atmosphere. This layer runs from the cloud base down to a near-surface region of supercritical carbon dioxide, at pressures found 900 metres beneath Earth's oceans. Understanding the deep atmosphere is essential to interpreting evidence of volcanic and seismic activity – key puzzle pieces in reconstructing Venus’ climate history – because its physical characteristics affect how we observe and perceive these signals.

In this talk, I describe the general circulation of the Venus deep atmosphere by combining simulations from the Venus Planetary Climate Model (VPCM) with Venus Express observations. The circulation resembles that predicted for slowly rotating exoplanets, with superrotation increasing with altitude and high-latitude waves driving variability in trace gas species. Measuring these waves could let us separate their signal from potential compositional changes caused by volcanic eruptions. I demonstrate this by simulating volcanic eruptions in the VPCM and comparing their lifetime to the background variability.