Publication Date:
2015-11-06
Description:
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 L S = 218° and L S = 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 UV doublet peak intensity is well correlated with simultaneous observations of solar 17–22 nm irradiance at Mars.
Print ISSN:
0094-8276
Electronic ISSN:
1944-8007
Topics:
Geosciences
,
Physics