GCM grid whiteGEM-Mars is a state-of-the-art three-dimensional Global Climate Model (GCM - sometimes called a General Circulation Model) for the atmosphere of Mars which describes the meteorology, circulation, dust, clouds, water, polar caps, radiation and atmospheric chemistry from the surface up to 170 km altitude.

It applies the dynamical core of the Global Environmental Multiscale model (GEM) which is part of the operational weather forecasting system of Environment and Climate Change Canada.



GCM HR TT Ice time4

The GCM simulates temperature and water ice clouds. This animation shows the evolution during one Mars day (called a sol) during the Martian northern spring/summer period. The colours indicate temperatures ranging from approximately -170C (blue) to -10C (red) on the surface and in a vertical slice along the equator. Clouds are represented by the white isosurfaces, and can be seen forming over the mountains at night. The topography of the surface is exaggerated to highlight Olympus Mons and the Tharsis Montes.

GEM-Mars also includes atmospheric chemistry reactions which helps to interpret observations of trace gases, for example, from ExoMars TGO/NOMAD. NOMAD recently observed ozone vertical profiles during two very different Martian years, one with a planet-encircling global dust event and the next year with no large dust event. It was observed that ozone was much reduced in the dust storm year compared to the next when no dust storm occurred. The GEM-Mars simulations with atmospheric chemistry in the global dust storm confirm this planet-wide ozone destruction, and help to understand the involved processes. This animation compares the simulations for the two Mars years, where the surface colour represents the amount of dust in the atmosphere and the slice shows the zonally averaged ozone volume mixing ratio. On the left is the global dust event year, on the right is the year without a global dust event. The reduction of ozone in the middle atmosphere can clearly be seen in the simulations. For more information, see Daerden et al., 2022.