Observations of a bimodal size distribution for the aerosol particles on Mars by SPICAM/MEX

A. Fedorova (1, 2) , Franck Montmessin (3) , A. Rodin (1, 2) , O. Korablev (1, 2) , Anni Määttänen (3) , L. Maltagliati (4) , Jean-Loup Bertaux (3)

1 IKI - Space Research Institute of the Russian Academy of Sciences
2 MIPT - Moscow Institute of Physics and Technology [Moscow]
3 PLANETO - LATMOS
4 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique

We present first results of simultaneous analysis of the ultraviolet (UV) and infrared (IR) atmospheric extinctions obtained by SPICAM on Mars Express by means of solar occultations in the Martian atmosphere in the beginning of the northern summer (Ls=56-97°) at the middle northern and southern latitudes. Based on Mie scattering theory with adequate refraction indices for dust and H2O ice, a bimodal distribution of aerosol has been inferred from the SPICAM measurements at the altitudes from 10 to 50 km. The coarser mode exists for both H2O and dust particles with average radius of 1.3 and 0.7 μm, respectively, with number density from 0.01 to 10 particles to cm3. In addition, a small mode has been detected in both hemispheres with a radius of 0.03-0.07 μm and a number density from 1 cm-3 at 60 km to 1,000 cm-3 at 10-20 km.

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]

A. Fedorova, Franck Montmessin, A. Rodin, O. Korablev, Anni Määttänen, et al.. Observations of a bimodal size distribution for the aerosol particles on Mars by SPICAM/MEX. European Planetary Science Congress 2013, Sep 2013, London, United Kingdom. pp.EPSC2013-508. ⟨hal-00906484⟩