Aerosols and clouds in the limb of Mars: A study with the VMC camera onboard Mars Express

The Visual Monitoring Camera on board Mars Express provides images of varied resolutions, covering a wide range of locations and seasons, and has been taking images for several Martian Years. Some of these images show clear instances of aerosols layers in the limb of the planet, which allow studying their height and extension. Images close to pericenter display varying morphologies, and the extensive coverage by VMC allows determining inter-annual and areographicaI variations in occurrence.

The first years of the database were explored in Sánchez-Lavega (2018a), but this study was conditioned by the fact that there was no scientific programming of the observations until 2016. Nowadays, after several years of planning, a much more complete set of observations is available, covering four Martian years, with the added interest that a global dust storm developed in one of them (Sanchez-Lavega et al, 2018b). In this work, we will present results of a systematic analysis that aims to extend this study to MYs 33-37, analyzing the extension and height of aerosols, their aerographic distribution and dependence on season and local time.

Figure 1: Aerographic distribution of aerosol detections. Blue, green and red indicate MYs 33, 34 and 35 respectively.

Figure 2: Seasonal distribution of aerosol detections. Blue, green and red indicate MYs 33, 34 and 35 respectively.

 In Figure 1  we present the aerographic  distribution of aerosols in MYs 34-35, and in Figure 2, the seasonal dependence. The systematic survey that started with the scientific planning of the observations implies that MY35 (in red in the figures) is much better covered, as also are MY 36 and 37, which will allow a good inter-annual comparison.

References:

• Clancy, R. Todd, et “Mars Clouds”, Chapter 5 in “The Atmosphere and Climate of Mars”. Ed. Robert M. Haberle, et al. CUP, 2017
• Sánchez-Lavega, A. et al. “Limb clouds and dust on Mars from images obtained by the Visual Monitoring Camera (VMC) onboard Mars Express” ICARUS 299, 194-205 (2018a)
• Sánchez-Lavega, et al. “The Onset and Growth of the 2018 Martian Global Dust Storm” Geophysical Research Letters, 46, 6101-6108 (2018b)