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

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.

[1]  M. Wolff,et al.  Diurnal Variations in the Aphelion Cloud Belt as Observed by the Emirates Exploration Imager (EXI) , 2022, Geophysical Research Letters.

[2]  P. Christensen,et al.  EMIRS Observations of the Aphelion‐Season Mars Atmosphere , 2022, Geophysical Research Letters.

[3]  D. Kubitschek,et al.  The Emirates Mars Mission , 2022, Space science reviews.

[4]  M. Wolff,et al.  Emirates Mars Mission Characterization of Mars Atmosphere Dynamics and Processes , 2021, Space Science Reviews.

[5]  V. A. Drake,et al.  The Emirates Exploration Imager (EXI) Instrument on the Emirates Mars Mission (EMM) Hope Mission , 2021, Space Science Reviews.

[6]  G. Mehall,et al.  The Emirates Mars Mission (EMM) Emirates Mars InfraRed Spectrometer (EMIRS) Instrument , 2021, Space Science Reviews.

[7]  E. Millour,et al.  Martian cloud climatology and life cycle extracted from Mars Express OMEGA spectral images , 2019, Icarus.

[8]  D. Scaccabarozzi,et al.  The current weather and climate of Mars: 12 years of atmospheric monitoring by the Planetary Fourier Spectrometer on Mars Express , 2021 .

[9]  Jagabandhu Panda,et al.  Observation of aphelion cloud belt over Martian tropics, its evolution, and associated dust distribution from MCS data , 2020 .

[10]  M. Malin,et al.  Mapping water ice clouds on Mars with MRO/MARCI , 2019, Icarus.

[11]  Michael D. Smith.  Local time variation of water ice clouds on Mars as observed by THEMIS. , 2015, Icarus.

[12]  F. Montmessin,et al.  Clouds in the Martian Atmosphere , 2018, Oxford Research Encyclopedia of Planetary Science.

[13]  Robert M. Haberle,et al.  The atmosphere and climate of Mars , 2017 .

[14]  S. Guzewich,et al.  Influence of water ice clouds on nighttime tropical temperature structure as seen by the Mars Climate Sounder , 2014 .

[15]  J. Bandfield,et al.  Retrievals of martian atmospheric opacities from MGS TES nighttime data , 2013 .

[16]  Michael D. Smith,et al.  Mars Global Surveyor Thermal Emission Spectrometer (Tes) Observations: Atmospheric Temperatures During Aerobraking and Science Phasing , 2013 .

[17]  J. Schofield,et al.  Water ice clouds over the Martian tropics during northern summer , 2010 .

[18]  Michael D. Smith.  THEMIS Observations of Mars Aerosol Optical Depth from 2002-2008 , 2009 .

[19]  Mark T. Lemmon,et al.  Constraints on dust aerosols from the Mars Exploration Rovers using MGS overflights and Mini‐TES , 2006 .

[20]  A. Colaprete,et al.  Significant vertical water transport by mountain‐induced circulations on Mars , 2006 .

[21]  G. Neumann,et al.  Diurnal variation and radiative influence of Martian water ice clouds , 2006 .

[22]  Michael D. Smith.  Interannual variability in TES atmospheric observations of Mars during 1999–2003 , 2004 .

[23]  R. Todd Clancy,et al.  Mars aerosol studies with the MGS TES emission phase function observations: Optical depths, particle sizes, and ice cloud types versus latitude and solar longitude , 2003 .

[24]  D. Paige,et al.  Viking‐era diurnal water‐ice clouds , 2003 .

[25]  M. Caplinger,et al.  The seasonal behavior of water ice clouds in the Tharsis and Valles Marineris regions of Mars: Mars Orbiter Camera Observations , 2003 .

[26]  David P. Hinson,et al.  Temperature inversions, thermal tides, and water ice clouds in the Martian tropics , 2003 .

[27]  S. Larson,et al.  Diurnal variation of Martian water-ice clouds in Tharsis region of the low latitude cloud belt: Observations in 1995–1999 apparitions , 2002 .