Séminaire
Convective vortices, with strong tangential wind speeds around a low pressure vortex core, often occur in the martian boundary layer at the edge of convective cells. If they are sufficiently large, and if there is enough surface dust present, they become visible as dust devils. Dust devils have been detected by every lander or rover to reach the surface of Mars, and they - or their tracks - are frequently seen from orbit over much of the martian surface. In addition, the dust raised by dust devils may be vital for maintaining the background dust loading in the martian atmosphere, for clearing bright surfaces and returning Mars’s albedo to normal following a global dust storm, and for cleaning dust off solar panels and other surfaces on landed missions. Understanding the physics of vortices on Mars, and how their size and the amount of dust they raise relates to planetary boundary layer properties, is therefore of great importance. I will present an overview of Mars dust devil theory and observations, then show how they may be modeled explicitly in very high resolution Large Eddy Simulations and how their effects may be parameterized in lower resolution models, focusing on results from the Curiosity rover in Gale Crater and predictions for the imminent InSight mission. I will also discuss why the InSight dataset should allow us to greatly improve our understanding of Mars dust devils, and hence our predictive ability.
marie-pierre.lefebvre@lmd.jussieu.fr