Martian water and dust meteorology

The intertwined dust and water cycles profoundly shape the Martian climate, but the mechanisms at stake are not well understood. The timing and occurrence of global dust storms remains a mystery. Global atmospheric transport water controls ice deposits, but is poorly understood in present and past Amazonian climates.

I tackle those questions by means of improved climate modeling, and showed how the microphysics of ice cloud formation and dust overwhelmingly controls the amount of water vapor injected by the polar caps into the atmosphere. Additionally, I developed a data assimilation of satellite observations - a technique developed for weather forecast – in order to reconstruct atmospheric fields by confronting measurements to model outputs in a mathematical optimal way. It resulted in a system able to predict dust transport and storm evolution.

Venus atmospheric dynamics

Despite its slow, retrograde solid body rotation, the atmosphere of Venus rotates much faster, with winds as fast as 120 m/s at its cloud top. How Venus became retrograde, how its rotation is currently balanced and what maintains atmospheric superrotation are some key questions for the evolution of Venus.

By adding the effects of mountain waves in an advanced circulation model, I revealed how and how much angular momentum is transfered between the atmosphere and the solid body. Using the unique capability of this model to extend from the surface to the thermosphere, I also explained the mysterious oxygen airglow behavior in the upper atmosphere, and showed that dynamics of the deep atmospheric and cloud level directly impact the thermosphere. These findings will be key to eventually obtain a complete budget of momentum transport in the whole atmosphere of Venus.

Venusian mountain wave seen by Akatsuki / numerically modeled
Habitability of terrestrial exoplanets
Amanda Smith /Science

Due to their cosmic abundance and long lifetimes, red dwarfs are by far the most abundant stars in the Universe. Planets orbiting in the habitable zone of these stars are tidally locked, most likely in synchronous rotation, with crucial consequences for their climate and habitability. However, there is no analogue in the Solar System of such configurations. As observations of terrestrial exoplanets remain challenging, their climate and habitability are left to speculation.

Numerical models remain our best tools to explore those worlds, and I used one to show how the strong gravitational tides have little to no impact on the climates of such planets. Moreover, I develop coupled ice and atmospheric models in order to understand where and how water can be trapped on the permanent nightside, and if ice sheets can impact the planet’s rotational dynamics.