Martian Atmospheric Aerosols Composition and Distribution Retrievals During the First Martian Year of NOMAD/TGO Solar Occultation Measurements: 2. Extended Results, End of MY 34 and First Half of MY 35

Abstract

This is the second part of Stolzenbach et al. (2023, https://doi.org/10.1029/2022JE007276), named hereafter Paper I, extends the period to the end of MY 34 and the first half of MY 35. This encompasses the end phase of the MY 34 Global Dust Storm (GDS), the MY 34 C-Storm, the Aphelion Cloud Belt (ACB) season of MY 35, and an unusual early dust event of MY 35 from LS 30° to LS 55°. The end of MY 34 overall aerosol size distribution shows the same parameters for dust and water ice to what was seen during the MY 34 GDS. Interestingly, the layered water ice vertical structure of MY 34 GDS disappears. The MY 34 C-Storm maintains condition like the MY 34 GDS. A high latitude layer of bigger water ice particles, close to 1 μm, is seen from 50 to 60 km. This layered structure is linked to an enhanced meridional transport characteristic of high intensity dust event which put the MY 34 C-Storm as particularly intense compared to non-GDS years C-Storms as previously suggested by Holmes et al. (2021, https://doi.org/10.1016/j.epsl.2021.117109). Surprisingly, MY 35 began with an unusually large dust event (Kass et al., 2020, https://ui.adsabs.harvard.edu/abs/2020AGUFMP039…01K) found in the Northern hemisphere during LS 35° to LS 50°. During this dust event, the altitude of aerosol first detection is roughly equal to 20 km. This is close to the values encountered during the MY 34 GDS, its decay phase and the C-Storm of the same year. Nonetheless, no vertical layered structure was observed.