Limb Observations of Solar Scattered Light by the Imaging Ultraviolet Spectrograph on MAVEN: New Constraints on Martian Mesospheric Cloud Variability

Abstract : The Imaging Ultraviolet Spectrograph (IUVS) on NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission observed the Martian upper atmosphere in late 2015 (Ls ~ 70) and early 2016 (Ls ~ 150). Although designed to measure the dayglow between 90-200 km IUVS also scans the limb down to 60 km, where solar scattered light dominates the mid-ultraviolet (MUV) signal. Occasionally, this MUV light shows enhanced scattering between 60-90 km indicating the presence of aerosols in the mesosphere. We quantify the solar scattering for each daylight scan obtained between October and December, 2015 and between April and June, 2016. We then identify over 100 scans of enhanced scattering between 60-90 km and assemble them both geographically and diurnally. The geographical distribution of the enhancements in 2015 is preferentially located near the equator, consistent with previous observations of mesospheric clouds for this part of the season. A wave three pattern in equatorial cloud occurrence suggests forcing from a non-migrating tide, possibly linked to the longitudinal variation of Mars surface topography. At the same time, there are indications of a diurnal variation such that the clouds seen in 2015 and 2016 are preferentially observed in the early morning, between 0600-0900 local solar time. This suggests an important role for a migrating temperature tide controlling the formation of Martian mesospheric clouds.
Type de document :
Communication dans un congrès
DPS 48 / EPSC 11 (Division for Planetary Sciences and the European Planetary Science Congress), Oct 2016, Pasadena, United States. American Astronomical Society, 48, pp.id.#409.08
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https://hal-insu.archives-ouvertes.fr/insu-01380220
Contributeur : Catherine Cardon <>
Soumis le : mercredi 12 octobre 2016 - 16:33:42
Dernière modification le : mercredi 21 mars 2018 - 18:58:00

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Michael H. Stevens, David E. Siskind, Scott Evans, Nicholas M. Schneider, A. Ian F. Stewart, et al.. Limb Observations of Solar Scattered Light by the Imaging Ultraviolet Spectrograph on MAVEN: New Constraints on Martian Mesospheric Cloud Variability. DPS 48 / EPSC 11 (Division for Planetary Sciences and the European Planetary Science Congress), Oct 2016, Pasadena, United States. American Astronomical Society, 48, pp.id.#409.08. 〈insu-01380220〉

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