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- Title
Vertical Aerosol Distribution and Mesospheric Clouds From ExoMars UVIS.
- Authors
Streeter, Paul M.; Sellers, Graham; Wolff, Michael J.; Mason, Jonathon P.; Patel, Manish R.; Lewis, Stephen R.; Holmes, James A.; Daerden, Frank; Thomas, Ian R.; Ristic, Bojan; Willame, Yannick; Depiesse, Cédric; Vandaele, Ann Carine; Bellucci, Giancarlo; López‐Moreno, José Juan
- Abstract
The vertical opacity structure of the martian atmosphere is important for understanding the distribution of ice (water and carbon dioxide) and dust. We present a new data set of extinction opacity profiles from the NOMAD/UVIS spectrometer aboard the ExoMars Trace Gas Orbiter, covering one and a half Mars Years (MY) including the MY 34 Global Dust Storm and several regional dust storms. We discuss specific mesospheric cloud features and compare with existing literature and a Mars Global Climate Model (MGCM) run with data assimilation. Mesospheric opacity features, interpreted to be water ice, were present during the global and regional dust events and correlate with an elevated hygropause in the MGCM, providing evidence that regional dust storms can boost transport of vapor to mesospheric altitudes (with potential implications for atmospheric escape). The season of the dust storms also had an apparent impact on the resulting lifetime of the cloud features, with events earlier in the dusty season correlating with longer‐lasting mesospheric cloud layers. Mesospheric opacity features were also present during the dusty season even in the absence of regional dust storms, and interpreted to be water ice based on previous literature. The assimilated MGCM temperature structure agreed well with the UVIS opacities, but the MGCM opacity field struggled to reproduce mesospheric ice features, suggesting a need for further development of water ice parameterizations. The UVIS opacity data set offers opportunities for further research into the vertical aerosol structure of the martian atmosphere, and for validation of how this is represented in numerical models. Plain Language Summary: The martian atmosphere contains several kinds of aerosol, including dust, water ice, and carbon dioxide ice. The NOMAD/UVIS spectrometer aboard the ExoMars Trace Gas orbiter is able to measure the opacity of the atmosphere at different heights by looking through the atmosphere at the Sun, and these opacities provide information on the vertical aerosol distribution. We present a new data set of these opacities for one and a half Mars Years, a period including one Global Dust Storm and several smaller regional‐scale dust storms. By comparing with a martian climate model and previous work we discuss some noteable features in the UVIS data. We see the presence of high‐altitude water ice clouds associated with the Global Dust Storm and several regional dust storms, and find that the lifetime of these cloud layers seems to depend on the seasonal timing of the relevant dust event. These layers also correlate with an elevated higher‐altitude water vapor presence, showing that large dust storms boost the upwards transport of water vapor; this could enhance atmospheric escape of hydrogen. The model temperature structure is consistent with the UVIS results, but the model aerosol field shows a need for improvement in its representation of high‐altitude water ice. Key Points: Mesospheric water ice clouds were present in ExoMars/UVIS opacity profiles during a global and three regional dust stormsMesospheric water ice correlated with elevated hygropause, showing storms boost vertical water transport with hydrogen escape implicationsPerihelion season mesospheric water ice was also present even in the absence of global/regional dust storm activity
- Subjects
TRACE gases; WATER vapor; DUST storms; WATER vapor transport; AEROSOLS; MARTIAN atmosphere; CARBON dioxide in water
- Publication
Journal of Geophysical Research. Planets, 2022, Vol 127, Issue 5, p1
- ISSN
2169-9097
- Publication type
Article
- DOI
10.1029/2021JE007065