Detection of Mesospheric CO₂ Ice Clouds on Mars in Southern Summer

F. Y. Jiang (1, 2) , Roger Yelle (1) , S. K. Jain (3) , J. Cui (4, 5) , Franck Montmessin (6) , N. M. Schneider (3) , Justin Deighan (3) , H. Gröller (1) , Loïc Verdier (7)

1 LPL - Lunar and Planetary Laboratory [Tucson]
2 CAS Key Laboratory of Lunar and Deep Space Exploration
3 LASP - Laboratory for Atmospheric and Space Physics [Boulder]
4 Space and Atmospheric Physics Group [London]
5 School of Atmospheric Sciences [Zhuhai]
6 PLANETO - LATMOS
7 LATMOS - Laboratoire Atmosphères, Milieux, Observations Spatiales

This paper reports the first detections of two high‐altitude nighttime CO2 clouds on Mars during southern summer (L_s = 264° and L_s = 330°) with stellar occultation measurements by the Imaging Ultraviolet Spectrograph on board the Mars Atmosphere and Volatile Evolution spacecraft. Interpretation of the transmission spectra with Mie theory indicates particle radii of ~90‐110 nm assuming a mono‐disperse distribution. The altitude profile of extinction indicates that the cloud layers are confined horizontally to sizes less than ~ 500‐700~km. Examination of the CO2 density and temperature profiles reveals strong wave‐like perturbations. Supersaturated temperatures occur at the maximum negative extent of these wave‐like perturbations, which are organized in longitude with a dominant m=3 zonal harmonic. This suggests that tides are important in the formation of CO2 clouds.

Domains: Sciences of the Universe [physics]

F. Y. Jiang, Roger Yelle, S. K. Jain, J. Cui, Franck Montmessin, et al.. Detection of Mesospheric CO₂ Ice Clouds on Mars in Southern Summer. Geophysical Research Letters, 2019, 46 (14), pp.7962-7971. ⟨10.1029/2019GL082029⟩. ⟨insu-02182518⟩