Challenges in Mars climate modelling with the LMD Mars Global Climate Model, now called the Mars “Planetary Climate Model” (PCM)

The Mars atmosphere Global Climate Model (GCM) developed at the Laboratoire de Météorologie Dynamique [1] in collaboration with several teams around the world (LATMOS, the Instituto de Astrofisica de Andalucia, UAE University, University of Oxford, The Open University), and with the support of ESA and CNES is currently used for many kinds of applications. It simulates Mars from the subsurface to the top of the thermosphere and includes the cycles of dust, water and CO2 that control the current Martian climate as well as a photo-chemical/ionospheric module. The aim of this modeling is high: ultimately to build a numerical simulator based only on universal equations, yet able to consistently reproduce available observations. The goal is to create a realistic virtual planet on which all observed phenomena and climate-induced geological landforms arise naturally. Like for the other similar models in the community, this specific goal is a scientific endeavour by itself. Such a GCM can also provide useful environmental predictions that can be used to process observations or prepare space missions. For this purpose our teams have produced the Mars Climate Database (See Millour et al., this issue) which provides climatologies derived from GCM simulations completed by dedicated tools. The GCM is also used to perform meteorological data assimilation to create an optimal description of the Martian environment obtained by combining observation and model simulations (See e.g. Young et al., Read et al., Holmes et al., this issue)

Water Supersaturation for Early Mars

International audienceEvidence of past liquid water flowing on the surface of Mars has been identified since the first orbital mission to the planet. However, reconstructing the climate that would allow liquid water at the surface is still an intense area of research. Previous studies showed that an atmosphere composed only of CO2 and H2O could not sustain surface temperatures above the freezing point of water. Different solutions have been studied, ranging from events like impacts on different atmospheric compositions, or even radiative feedback of water clouds that would create a dramatic greenhouse effect. In this context, we propose to study whether the supersaturation of water could warm the planet. Strong supersaturation is observed in the present-day Martian atmosphere. On early Mars, supersaturation could enhance the greenhouse effect through strong absorption of the IR flux by water vapor or by modifying water clouds. While 1D modeling suggests a significant impact, our 3D model shows that warming the climate of early Mars requires a high supersaturation ratio, especially in the lower layers of the atmosphere. This configuration seems highly unrealistic since the level of supersaturation is higher than what would be expected in a dense atmosphere

Challenges in Mars Climate Modelling with the LMD Mars Global Climate Model, Now Called the Mars “Planetary Climate Model” (PCM)

International audienc

Challenges in Mars Climate Modelling with the LMD Mars Global Climate Model, Now Called the Mars “Planetary Climate Model” (PCM)

International audienc

Challenges in Mars Climate Modelling with the LMD Mars Global Climate Model, Now Called the Mars “Planetary Climate Model” (PCM)

International audienc

Challenges in Mars Climate Modelling with the LMD Mars Global Climate Model, Now Called the Mars “Planetary Climate Model” (PCM)

International audienc