Detection of green line emission in the dayside atmosphere of Mars from NOMAD-TGO observations

Gérard, Jean‐Claude; Aoki, Shohei; Willame, Yannick; Gkouvelis, Leonardos; Depiesse, C.; Thomas, Ian; Ristic, Bojan; Vandaele, Ann Carine; Daerden, Frank; Hubert, Benoît; Mason, Jon; Patel, Manish R.; López-Moreno, J. J.; Bellucci, Giancarlo; López‐Valverde, M. Á.; Beeckman, Bram

doi:10.1038/s41550-020-1123-2

Cited by 16 publications

(44 citation statements)

References 21 publications

(23 reference statements)

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“…Simulations of auroral electron impact on CO 2 , CO and O producing O( 1 S) indicate that collisions with CO 2 dominates over the other two processes. The oxygen 557.7-nm/297.2nm ratio of Einstein coefficients recommended by NIST is 16.4 (Kramida et al, 2019), and was recently confirmed by Gérard et al (2020), based on dayglow measurements on Mars from TGO-UVIS.…”

Section: Model Descriptionmentioning

confidence: 77%

Discrete Aurora on Mars: Spectral Properties, Vertical Profiles, and Electron Energies

et al. 2021

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Since 2005, Mars has progressively revealed that its atmosphere is glowing with several types of aurorae. So far, three types of aurorae have been observed in the Martian atmosphere: discrete aurorae, diffuse aurorae, and proton aurorae.Chronologically, discrete aurorae were first discovered with the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM) instrument on board European Space Agency's (ESA)

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Section: Model Descriptionmentioning

confidence: 77%

Discrete Aurora on Mars: Spectral Properties, Vertical Profiles, and Electron Energies

et al. 2021

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“…(2018, 2020a) and Gérard et al. (2019, 2020). The sources of O( 1 D) in the Martian upper atmosphere are listed in Table 2.…”

Section: Model Simulations For Uvis Observing Conditionsmentioning

confidence: 97%

“…The methodology adopted for this study is similar to the approach described by Gérard et al. (2020). The TGO spacecraft is on a circular Martian orbit at ∼400 km inclined by 74° on the planetary equator since October 2016.…”

Section: Limb Observations Of Oxygen Linesmentioning

confidence: 99%

First Observation of the Oxygen 630 nm Emission in the Martian Dayglow

Gérard

Aoki

Gkouvelis

et al. 2021

Geophysical Research Letters

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The first Martian dayglow observations were collected with the ultraviolet spectrometers on board Mariner 6, 7, and 9 flown to Mars in the early 1970s (Barth, 1974). They identified the presence of a series of oxygen and carbon lines and molecular bands originating from CO and CO 2 + . They obtained limb profiles of the strongest emissions. High quality extreme ultraviolet disk spectra were collected with the Hopkins Ultraviolet Telescope by Feldman et al. (2000). Later, limb observations with the SPICAM instrument on board Mars Express identified N 2 Vegard-Kaplan emissions in the middle ultraviolet (Leblanc et al., 2007). A major step forward was made with the Imaging Ultraviolet Spectrograph (IUVS) spectral imager on board the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft, which has collected a wealth of ultraviolet limb scans (Jain et al., 2015).The possible presence of visible dayglow emissions in the Martian dayglow was investigated by Fox and Dalgarno (1979) who modeled the sources and sinks of O( 1 S) metastable atoms that produce emission of the green line and trans-auroral emissions at 555.7 and 297.2 nm respectively. They also predicted the

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“…During the NOMAD-TGO observation period, the background intensity level around wavelength 6300 Å is equivalent to more than 10 kR. Moreover, the [OI] red-doublet emission lines are closer to the longer wavelength limit of the NOMAD-TGO instrument and the detector has a reduced sensitivity in this region, which is the main reason for the absence of these emissions in the observed dayside spectra (personal communication, Gérard et al, 2020). Furthermore, most of the NOMAD-TGO observations took place when Mars was moving away from the Sun.…”

Section: Effect Of Input Parameters On the Modelled Red-doublet Limb ...mentioning

confidence: 99%

“…The observation of [OI] 2972 Å emission has been done in the Martian upper atmosphere by several spacecraft-borne ultraviolet spectrometers starting from Mariner 6 to the recent MAVEN mission (Stewart, 1972;Leblanc et al, 2006;Jain et al, 2015). But the observation of [OI] 5577 Å emission had never been reported in the dayside of Martian upper atmosphere until the recent detection from Nadir and Occultation for Mars Discovery ultraviolet and visible spectrometer instrument on board the European Space Agency's Ex-oMars Trace Gas Orbiter (NOMAD-TGO) by Gérard et al (2020). Owing to its wide detection range (2000-6500 Å), this spectrometer is capable of observing the four forbidden atomic oxygen emissions ([OI] 2972, 5577, 6300, and 6364 Å) simultaneously in the Martian upper atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Forbidden atomic oxygen emissions in the Martian dayside upper atmosphere

Raghuram,

Jain,

Bhardwaj

2020

Preprint

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Recently, Nadir and Occultation for Mars Discovery (NOMAD) ultraviolet and visible spectrometer instrument on board the European Space Agency's ExoMars Trace Gas Orbiter (TGO) simultaneously measured the limb emission intensities for both [OI] 2972 and 5577 Å (green) emissions in the dayside of Martian upper atmosphere. But the atomic oxygen red-doublet emission lines ([OI] 6300 and 6364 Å), which are expected to be observed along with [OI] 5577 and 2972 Å emissions, are found to be absent in the NOMAD-TGO dayside observed spectra. We aim to explore the photochemistry of all these forbidden atomic oxygen emissions ([OI] 2972, 5577, 6300, 6464 Å) in the Martian daylight upper atmosphere and suitable conditions for the simultaneous detection of these emissions lines in the dayside visible spectra. A photochemical model is developed to study the production and loss processes of O( 1 S) and O( 1 D), which are the respective excited states of green and red-doublet emissions, by incorporating various chemical reactions of different O-bearing species in the upper atmosphere of Mars. By reducing Fox ( 2004) modelled neutral density profiles by a factor of 2, the calculated limb intensity profiles for [OI] 5577 and 2972 Å emissions are found to be consistent with the NOMAD-TGO observations. In this case, at altitudes below 120 km, our modelled limb intensity for [OI] 6300 Å emission is smaller by a factor 2 to 5 compared to that of NOMAD-TGO observation for [OI] 2972 Å emission, and above this distance it is comparable with the upper limit of the observation. We studied various parameters which can influence the limb intensities of these atomic oxygen forbidden emission lines. Our calculated limb intensity for [OI] 6300 Å emission, when the Mars is at near perihelion and for solar maximum condition, suggests that all these forbidden emissions should be observable in the NOMAD-TGO visible spectra taken on the dayside of Martian upper atmosphere. More simultaneous observations of forbidden atomic oxygen emission lines will help to understand the photochemical processes of oxygen-bearing species in the dayside Martian upper atmosphere.

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Detection of green line emission in the dayside atmosphere of Mars from NOMAD-TGO observations

Cited by 16 publications

References 21 publications

Discrete Aurora on Mars: Spectral Properties, Vertical Profiles, and Electron Energies

Discrete Aurora on Mars: Spectral Properties, Vertical Profiles, and Electron Energies

First Observation of the Oxygen 630 nm Emission in the Martian Dayglow

Forbidden atomic oxygen emissions in the Martian dayside upper atmosphere

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