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Diurnal variations in the aphelion cloud belt as observed by the Emirates Exploration Imager (EXI)
  • +9
  • Michael J. Wolff,
  • Anton Fernando,
  • Michael D. Smith,
  • François Forget,
  • Ehouarn Millour,
  • Samuel A Atwood,
  • Andrew Jones,
  • Mikki M. Osterloo,
  • Ralph Shuping,
  • Mariam AlShamsi,
  • Christopher Jeppsesen,
  • Charles Fisher
Michael J. Wolff
Space Science Institute

Corresponding Author:[email protected]

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Anton Fernando
2Laboratory for Atmospheric and Space Physics
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Michael D. Smith
NASA Goddard Space Flight Center
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François Forget
LMD
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Ehouarn Millour
Laboratoire de Meteorologie Dynamique
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Samuel A Atwood
Laboratory for Atmospheric and Space Physics
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Andrew Jones
Laboratory for Atmospheric and Space Physics
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Mikki M. Osterloo
Space Science Institute
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Ralph Shuping
Space Science Institute
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Mariam AlShamsi
Mohammed bin Rashid Space Center
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Christopher Jeppsesen
Laboratory for Atmospheric and Space Physics
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Charles Fisher
Laboratory for Atmospheric and Space Physics
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Abstract

Observations by the Emirates eXploration Imager (EXI) on-board the Emirates Mars Mission are used to characterize the diurnal, seasonal, and spatial behavior of Aphelion Cloud Belt during Mars Year 36 L$_S$$\sim$30$^\circ$-190$^\circ$. Building from previously work with the Mars Color Imager (MARCI) onboard the Mars Reconnaissance Orbiter, we retrieve water ice extinction optical depth ($\tau_{ice}$) with an uncertainty $\pm$0.022 (excluding particle size effects). We connect EXI and MARCI using radiance and $\tau_{ice}$. Zonal and meridional diurnal trends are analyzed over 6h-18h Local True Solar Time. The retrievals show large morning-evening asymmetries about a minimum near 12h. The latitudinal distributions in early morning are extensive and particularly striking near mid-summer. Comparisons to the Mars Planetary Climate Model show reasonable agreement with the basic diurnal behavior, but noticeable departures include too much water ice in early morning, the general latitudinal extent, and behavior smaller scales like the volcanoes and other topographically distinct features.