Waves in thin air with wide effects

Mars has a very thin atmosphere, with nearly one hundredth the density of ours on Earth, and gravity pulls with little more than one third of the strength we feel on our planet. As a result, dust storms can go global. For future missions to Mars, it is important to understand the planet’s airy envelope and to forecast its moods.

A new study1, led by Gabriella Gilli, of Instituto de Astrofísica e Ciências do Espaço (IA2) and Faculdade de Ciências da Universidade de Lisboa (Ciências ULisboa), published in the Journal of Geophysical Research, may improve the way we describe and forecast the Martian weather. This study suggests that waves moving upwards across Mars’ thin air, and caused by air perturbations, can have a strong impact on the atmosphere as a whole. Understanding this process may explain some of the differences between what space missions have observed on the red planet and the computer simulations scientists are using to figure out how its atmosphere works.

Atmospheric gravity waves3 are small fluctuations in air density and temperature propagating through the atmosphere. They can be produced by a number of processes, like warm and cool air interactions, or the flow of air over mountains, all of them perturbing the stable layering of the atmosphere. As these waves transport and release energy, they cause winds either to speed up, or to slow down to gentle breezes. Thus, they are known to have a role in the global atmospheric circulation on Earth, as well as on Mars and Venus.

“We focused on the comparison between our tridimensional simulations of the atmosphere4 and the observations by the instrument Mars Climate Sounder on board of Mars Reconnaissance Orbiter5,” says Gabriella Gilli. “The inclusion in the model of gravity waves produced by convection6 gives a plausible physical explanation for some of the remaining divergences between the observations and the simulations.”

Full details at IA’s press-release.

Part of my work as science communicator and public information officer at Instituto de Astrofísica e Ciências do Espaço (IA).