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First year of observations from TGO/NOMAD UVIS: retrievals of ozone on Mars
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Arianna Piccialli1, Ann Carine Vandaele1, Y. Willame1, C. Depiesse1, L. Trompet1, L. Neary1, S. Viscardy1, F. Daerden1, Ian R. Thomas1, Bojan Ristic1, J.P. Mason2, M.R. Patel2, Giancarlo Bellucci3, Jose-Juan Lopez-Moreno4, and
the NOMAD Team.
(Twitter: @apic79)
(1) Belgian Institute for Space Aeronomy, Belgium, (2) Open University, UK, (3) INAF, Istituto di Astrofisica e Planetologia Spaziali, Italy, (4) IAA/CSIC, Granada, Spain
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UVIS channel• Nadir and Solar occultation• Climatology of Ozone, UV level• Dust, clouds
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UVIS solar occultations
UVIS channel
• Wvl range: 200–650 nm• Spectral resolution: 1–2 nm• Vertical sampling : <300 m
• From April 2018 to August 2019:• 2738 solar occultations!
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Ozone climatology
Ozone is anti-correlatedwith water vapor
Daerden et al., 2019
Ozone
Watervapor
GEM-Mars GCM(General Circulation Model)
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Ozone: 1 year of NOMAD observations
May (Ls ~ 180-185)
July (Ls ~ 205)
September (Ls ~ 250°)
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Martian atmosphere @the terminator
Diurnal cycle of ozone (3D GCM)
Atmosphere simulated by the 3D GEM-Mars GCM (Neary, L. et al., 2017).
– complex photochemistry driven by thesolar illumination
– rapid timescales of photochemistry atsunrise and sunset
– Ozone (O3) is more abundant during thenighttime, especially above 40-50 km.
– As the Sun rises, the destruction of O3,although stronger in the high atmosphere,is observed at all altitudes.
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Before the dust storm
Lat= 76, Lon= 88, Ls =189
Lat= -82, Lon= -42, Ls =196
Lat= -23, Lon= 17, Ls =170
Ozone
Dust/aerosols
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During the dust storm
Lat= 66, Lon= 27, Ls =222
Lat= -15, Lon= -172, Ls =232
Lat= -46, Lon= -124, Ls =227
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During the dust storm
Lat= 5.5, Lon= -173, Ls =201
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After the dust stormLat= 17, Lon= -161, Ls =334 Lat= -74, Lon= 16, Ls =343
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A Radiative transfer code: ASIMUT
• Possibility to retrieve columns and/or profiles of atmospheric constituents simultaneously from different spectra, different geometries
• New improvement: consider the gradients across the terminator:– Temperature and total density gradients
– Density gradient for specific species (here: O3)
Vandaele et al. 2008Piccialli et al., 2019
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ASIMUT: inputs
• Preliminary Retrievals:– Input atmosphere: GEM-GCM profiles at specific
location– No gradients: spherical symmetry– Straylight correction partly implemented
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O3 maps (4/2018 – 9/2019)
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O3 maps (4/2018 – 9/2019)
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O3 maps (4 – 7/2018)
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O3 maps (4 – 7/2018)
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O3 maps 4 – 7/2018
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O3 maps (2/2019)
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O3 maps (2/2019)
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Summary
Retrieval of ozone from UVIS solar occultations:
• 2738 occultations between April 2018-August 2019
• The Radiative Transfer Model used at BIRA-IASB, ASIMUT, isimplemented for UVIS/NOMAD data.
• Ozone abundance is higher at high latitudes
• We observe two ozone layers: one below 30 km and a secondlayer at between 30-40 km. An upper layer at 60 km need to beconfirmed.
• Future work:
– Take in account gradients along the line of sights
– Retrieval of aerosols
– Climatology of ozone and dust (and comparison to H2O)