The structure and variability of Mars upper atmosphere as seen in MAVEN/IUVS dayglow observations

Sonal K. Jain (1) , A. Ian F. Stewart (1) , Nick M. Schneider (1) , Justin Deighan (1) , Arnaud Stiepen (1) , J. Scott Evans (2) , Michael H. Stevens (3) , Michael S. Chaffin (1) , Matteo Crismani (1) , William E. Mcclintock (1) , John T. Clarke (4) , Greg M. Holsclaw (1) , Daniel Y. Lo (5) , Franck Lefèvre (6) , Franck Montmessin (6) , E. M. B. Thiemann (1) , F. Eparvier (1) , Bruce M. Jakosky (1)

1 LASP - Laboratory for Atmospheric and Space Physics [Boulder]
2 Computational Physics, Inc.
3 NRL - Naval Research Laboratory
4 CSP - Center for Space Physics [Boston]
5 LPL - Lunar and Planetary Laboratory [Tucson]
6 PLANETO - LATMOS

We report a comprehensive study of Mars dayglow observations focusing on upper atmospheric structure and seasonal variability. We analyzed 744 vertical brightness profiles comprised of ∼109,300 spectra obtained with the Imaging Ultraviolet Spectrograph (IUVS) aboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) satellite. The dayglow emission spectra show features similar to previous UV measurements at Mars. We find a significant drop in thermospheric scale height and temperature between LS = 218° and LS = 337–352°, attributed primarily to the decrease in solar activity and increase in heliocentric distance. We report the detection of a second, low-altitude peak in the emission profile of OI 297.2 nm, confirmation of the prediction that the absorption of solar Lyman alpha emission is an important energy source there. The inline image UV doublet peak intensity is well correlated with simultaneous observations of solar 17–22 nm irradiance at Mars.

Mots clés: IUVS; dayglow; MAVEN; Mars

Domaines: Planétologie et astrophysique de la terre [astro-ph.EP]; Astrophysique stellaire et solaire [astro-ph.SR]

Sonal K. Jain, A. Ian F. Stewart, Nick M. Schneider, Justin Deighan, Arnaud Stiepen, et al.. The structure and variability of Mars upper atmosphere as seen in MAVEN/IUVS dayglow observations. Geophysical Research Letters, 2015, 42 (21), pp.9023-9030. ⟨10.1002/2015GL065419⟩. ⟨insu-01238335⟩