The water cycle in the Mars PCM : Comparison of seasonal frost dissipation and polar hood presence around the North Pole with OMEGA and MARCI observations

The Mars Planetary Climate Model (PCM) is a powerful tool capable of reproducing the main aspects and variables (temperature, humidity, pressure, atmospheric CO2 content, wind, etc.) of the Martian climate. But some features of the water cycle need to be explained and possibly corrected.

In this study, we focus on 2 aspects that could explain some limitations of the model :

the regression and dissipation of seasonal CO2 and H2O frosts around the North pole at the end of winter until the summer solstice (Ls = ~300 ° to 90°).

The formation of polar clouds, which rapidly cover completely the north polar residual cap and form the polar hood at the end of summer.

In the first part, we compare the regression of H2O and CO2 frost limits calculated in the PCM with the corresponding regression of frost derived from observations by the OMEGA spectro-imager. Seasonal frosts evolve in parallel, with a faster dissipation in the OMEGA data at the end of the regression phase (after Ls = 60°).

In the second, more forward-looking part, we attend to determine the arrival of the polar hood over the North Pole at the end of summer / beginning of autumn, based on the use of series of MARCI images.