Diurnal Variability in EMIRS Daytime Observations of Water Ice Clouds During Mars Aphelion-Season

Samuel A. Atwood, Michael D. Smith, Khalid Badri, Christopher S. Edwards, Philip R. Christensen, Michael J. Wolff, François Forget, Saadat Anwar, Nathan Smith, M. R. El-Maarry

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Diurnal analyses of water ice cloud optical depths retrieved from thermal infrared spectra by the Emirates Mars Infrared Spectrometer showed changing cloud abundance throughout the Martian day. Observations began with the start of the Emirates Mars Mission science phase near the beginning of aphelion-season in Mars Year 36 and included the prominent aphelion cloud belt (ACB) and orographic clouds in the vicinity of volcanoes. A midday minimum with higher morning and afternoon optical depths was typical for the ACB, though with considerable spatial variability in this diurnal pattern. Clouds near volcanoes reached a minimum before local noon and tended to increase in abundance throughout the afternoon. Comparisons against the Laboratoire de Météorologie Dynamique global circulation model showed analogous spatial patterns in the diurnal signal, which suggested thermal tides and topographic effects to be the predominant drivers of ACB variability, while more localized circulations affected volcano clouds.

Original languageEnglish (US)
Article numbere2022GL099654
JournalGeophysical Research Letters
Issue number15
StatePublished - Aug 16 2022

ASJC Scopus subject areas

  • Geophysics
  • General Earth and Planetary Sciences


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