Effect of the 2018 Martian Global Dust Storm on the CO2 Density in the Lower Nightside Thermosphere Observed From MAVEN/IUVS Lyman‐Alpha Absorption. Issue 7 (25th March 2020)

• Record Type: Journal Article
• Authors: Chaufray, J.‐Y.; Chaffin, M.; Deighan, J.; Jain, S.; Schneider, N.; Mayyasi, M.; Jakosky, B.
• Is Part Of: Geophysical research letters. Volume 47:Issue 7(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-03-25
• Subjects: Mars -- thermosphere -- dust -- UV -- Lyman‐alpha; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2019GL082889
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: The MAVEN/Imaging Ultraviolet Spectrograph (IUVS) instrument measures Lyman‐α emissions from interplanetary and Martian hydrogen at the limb and through the extended corona of Mars. In June 2018, a global dust storm (GDS) surrounded Mars for a few months, heating the lower atmosphere and leading to an expansion of the Martian atmosphere. Nightside IUVS observations before and throughout this GDS showed the altitude of CO2 absorption of Lyman‐α photons in the thermosphere to increase by 4.5±1.0 km on 8 June 2018. This shift is attributed to an increase of the CO2 density by a factor 1.9±0.2 at 110 km due to the heating of the lower atmosphere. These nightside observations, not previously used to study dust storms, in an altitude range not sampled by other instruments, are consistent with dayside MAVEN observations and allow for more comprehensive determination of the global changes produced by the GDS on the Martian thermosphere. Key Points: We observe an increase of the altitude of the Lyman‐alpha absorption by CO2 on 8 June 2018 due to the planet encircling dust event We estimate the increase of CO2 density at 110 km by a factor 1.9 The derived nightside density variation is consistent with the variations observed on dayside by other instruments