Mars ultraviolet dayglow variability: SPICAM observations and comparison with airglow model

Cox, Cédric; Gérard, Jean‐Claude; Hubert, Benoît; Bertaux, Jean-Loup; Bougher, S. W.

doi:10.1029/2009je003504

Cited by 27 publications

(51 citation statements)

References 48 publications

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“…A comparison of the obtained spectra with previous analyses of the SPICAM data set (Cox et al, ; Leblanc et al, ) shows a fully similar spectral shape but slightly lower intensities in our analysis for the Cameron bands and a larger difference (around 30%) for the CO

_{2}^{+}

UV doublet (not shown). This is mainly due to the use of a different detector efficient area.…”

Section: Comparison With Spicam Observationssupporting

confidence: 83%

“…A similar plot, but for the CO

_{2}^{+}

UV doublet, is shown in Figure . No graph showing the SZA variability of this emission was included in Leblanc et al () and Cox et al (). We have nevertheless included UV doublet peak intensities for three ranges of SZA from Figure 8 of Leblanc et al (), shown as green points in Figure .…”

Section: Comparison With Spicam Observationsmentioning

confidence: 99%

“…Different theoretical models have been developed in order to simulate the UV dayglow spectra and contribute to the interpretation of their measurements (Cox et al, ; Evans et al, ; Fox & Dalgarno, ; Gronoff et al, ; Jain & Bhardwaj, ; Shematovich et al, ; Simon et al, ). Whereas they use different approaches and techniques, they all coincide in that they are 1‐D models, that is, they only consider variations with altitude.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

UV Dayglow Variability on Mars: Simulation With a Global Climate Model and Comparison With SPICAM/MEx Data

et al. 2018

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A model able to simulate the CO Cameron bands and the CO 2+ UV doublet, two of the most prominent UV emissions in the Martian dayside, has been incorporated into a Mars global climate model. The model self‐consistently quantifies the effects of atmospheric variability on the simulated dayglow for the first time. Comparison of the modeled peak intensities with Mars Express (MEx) SPICAM (Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars) observations confirms previous suggestions that electron impact cross sections on CO2 and CO need to be reduced. The peak altitudes are well predicted by the model, except for the period of MY28 characterized by the presence of a global dust storm. Global maps of the simulated emission systems have been produced, showing a seasonal variability of the peak intensities dominated by the eccentricity of the Martian orbit. A significant contribution of the CO electron impact excitation to the Cameron bands is found, with variability linked to that of the CO abundance. This is in disagreement with previous theoretical models, due to the larger CO abundance predicted by our model. In addition, the contribution of this process increases with altitude, indicating that care should be taken when trying to derive temperatures from the scale height of this emission. The analysis of the geographical variability of the predicted intensities reflects the predicted density variability. In particular, a longitudinal variability dominated by a wave‐3 pattern is obtained both in the predicted density and in the predicted peak altitudes.

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_{2}^{+}

UV doublet (not shown). This is mainly due to the use of a different detector efficient area.…”

Section: Comparison With Spicam Observationssupporting

confidence: 83%

“…A similar plot, but for the CO

_{2}^{+}

Section: Comparison With Spicam Observationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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UV Dayglow Variability on Mars: Simulation With a Global Climate Model and Comparison With SPICAM/MEx Data

et al. 2018

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“…An average altitude offset of 2.4 km was found by Cox et al (2010) in their study of the SPICAM observations of the two emissions. Since the altitude of the two emissions covary and because the two CO 2 + UVD sources are both directly related to the CO 2 density distribution, we mainly concentrate on the comparison between the observed and simulated CO 2 + UV doublet emission.…”

Section: 1029/2019ja026596mentioning

confidence: 88%

MAVEN‐IUVS Observations of the CO₂⁺ UV Doublet and CO Cameron Bands in the Martian Thermosphere: Aeronomy, Seasonal, and Latitudinal Distribution

et al. 2019

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We analyze two Martian years of dayglow measurements of the CO Cameron bands and the CO2+ ultraviolet doublet (UVD) at 298–299 nm with the Imaging UltraViolet Spectrograph on board the Mars Atmosphere and Volatile EvolutioN (MAVEN) orbiter. We show that the altitude and the brightness of the two emissions peaks are strongly correlated, although data were collected over a wide range of latitudes and seasons. Averaged limb profiles are presented and compared with numerical simulations based on updated calculations of the production of the CO (a3Π) and the CO2+ (B 2Σ) states. The model simulations use the solar flux directly measured on board MAVEN with the Extreme Ultraviolet Monitor and the neutral densities provided by the Mars Climate Database version 5.3, adapted to the conditions of the observations. We show that the altitude and the shape of the sample limb profiles are well reproduced using the Mars Climate Database neutral atmosphere. The simulated peak intensities of the CO2+ UVD and Cameron bands are in good agreement considering the uncertainties on the excitation cross sections and the calibration of the Imaging Ultraviolet Spectrograph (IUVS) and Extreme Ultraviolet Monitor instruments. No significant adjustment of the electron impact cross section on CO2 to produce the a3Π state is needed. Seasonal‐latitudinal maps of the Cameron and UVD peak altitude observed during two Martian years show variations as large as 23 km. Model simulations of the amplitude of these changes are in fair agreement with the observations except during the southern summer dust period (Ls = 270–320°) when the calculated rise of the dayglow layer is underestimated.

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“…Therefore, the value reported by Avakyan et al [1998] is 2.4 10 −16 cm −2 at 80 eV, and the correction has been applied for all the energies. Such a correction was known to be too high to account for the observed Cameron bands at Mars [ Erdman and Zipf , 1983], and the newly reevaluated cross section was divided by 2 in Simon et al [2009], Cox et al [2010], and Jain and Bhardwaj [2011b]. The recent experimental and theoretical work by Gilijamse et al [2007] re‐analyzed the radiative lifetime of CO(a 3 Π), and found a value of 3.16 ms, which is 3 times less than the value of [ Johnson , 1972] used previously to correct the cross sections.…”

Section: The Emission Uncertainties Sourcesmentioning

confidence: 99%

Computing uncertainties in ionosphere‐airglow models: II. The Martian airglow

Gronoff¹,

Wedlund²,

Mertens³

et al. 2012

J. Geophys. Res.

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[1] One of the objectives of spectrometers onboard space missions is to retrieve atmospheric parameters (notably density, composition and temperature). To fulfill this objective, comparisons between observations and model results are necessary. Knowledge of these model uncertainties is therefore necessary, although usually not considered, to estimate the accuracy in planetary upper atmosphere remote sensing of these parameters. In Part I of this study, "Computing uncertainties in ionosphere-airglow models: I. Electron flux and species production uncertainties for Mars" (Gronoff et al., 2012), we presented the uncertainties in the production of excited states and ionized species from photon and electron impacts, computed with a Monte-Carlo approach, and we applied this technique to the Martian upper atmosphere. In the present paper, we present the results of propagation of these production errors to the main UV emissions and the study of other sources of uncertainties. As an example, we studied several aspects of the model uncertainties in the thermosphere of Mars, and especially the O( 1 S) green line (557.7 nm, with its equivalent, the trans-auroral line at 297.2 nm), the Cameron bands CO(a 3 P), and CO 2 + (B 2 S u + ) doublet emissions. We first show that the excited species at the origin of these emissions are mainly produced by electron and photon impact. We demonstrate that it is possible to reduce the computation time by decoupling the different sources of uncertainties; moreover, we show that emission uncertainties can be large (>30%) because of the strong sensitivity to the production uncertainties. Our study demonstrates that uncertainty calculations are a crucial step prior to performing remote sensing in the atmosphere of Mars and the other planets and can be used as a guide to subsequent adjustments of cross sections based on aeronomical observations. Finally, we compare the simulations with observations from the SPICAM spectrometer on the Mars Express spacecraft. The production of excited species at the origin of the green line, the CO Cameron bands and the CO 2 + (B) doublet is found to be on the dayside, consistent with photon and electron impact on CO 2 as the main source of excitation of the three emissions, in contrast to the findings of Huestis et al. (2010) for the O( 1 S) case. Moreover, we re-examine the cross section for the production of the Cameron bands by electron impact on CO 2 .

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Mars ultraviolet dayglow variability: SPICAM observations and comparison with airglow model

Cited by 27 publications

References 48 publications

UV Dayglow Variability on Mars: Simulation With a Global Climate Model and Comparison With SPICAM/MEx Data

UV Dayglow Variability on Mars: Simulation With a Global Climate Model and Comparison With SPICAM/MEx Data

MAVEN‐IUVS Observations of the CO₂⁺ UV Doublet and CO Cameron Bands in the Martian Thermosphere: Aeronomy, Seasonal, and Latitudinal Distribution

Computing uncertainties in ionosphere‐airglow models: II. The Martian airglow

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Mars ultraviolet dayglow variability: SPICAM observations and comparison with airglow model

Cited by 27 publications

References 48 publications

UV Dayglow Variability on Mars: Simulation With a Global Climate Model and Comparison With SPICAM/MEx Data

UV Dayglow Variability on Mars: Simulation With a Global Climate Model and Comparison With SPICAM/MEx Data

MAVEN‐IUVS Observations of the CO2+ UV Doublet and CO Cameron Bands in the Martian Thermosphere: Aeronomy, Seasonal, and Latitudinal Distribution

Computing uncertainties in ionosphere‐airglow models: II. The Martian airglow

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MAVEN‐IUVS Observations of the CO₂⁺ UV Doublet and CO Cameron Bands in the Martian Thermosphere: Aeronomy, Seasonal, and Latitudinal Distribution