Modeling the atmospheric limb emission of CO2 at 4.3 μm in the terrestrial planets

López‐Valverde, M. Á.; López‐Puertas, M.; Funke, B.; Gilli, Gabriella; García‐Comas, M.; Drossart, P.; Piccioni, G.; Formisano, V.

doi:10.1016/j.pss.2010.02.001

Cited by 22 publications

(20 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For instance, the Venus Express VIRTIS spectra around 4.3 µm for tangent heights above 100-110 km, which are discussed in Gilli et al (2009) and López-Valverde et al (2011a), demonstrate remarkable resemblance of Mars Express PFS spectra analyzed in this study. Due to a well-known similarity of the CO 2 daytime emission formation mechanisms for both planets (Ogibalov and Kutepov, 1989) the Venus spectra obviously also require detailed rotational non-LTE/line overlapping analysis.…”

Section: Discussionsupporting

confidence: 59%

“…These levels are strongly pumped by the absorption of solar radiation at 2.7 µm and give origin to the two strong SH bands, which dominate the 4.3 µm limb emissions (Gilli et al, 2009;López-Valverde et al, 2011a) of the Martian middle and upper atmosphere discussed here. We accounted for rotational sublevels up to j = 102 for each of these vibrational levels.…”

Section: Rotational Lte and Non-ltementioning

confidence: 75%

“…A. A number of studies (López-Valverde et al, 2005;Formisano et al, 2006;López-Valverde et al, 2011a, b) (hereafter "previous studies") were undertaken in recent years aimed at interpretation of the PFS SWC limb spectra. These studies consider only vibrational non-LTE in CO 2 assuming molecular rotations completely thermalized (rotational LTE) and reiterate main features of daytime 4.3 µm CO 2 emission formation in the upper atmosphere, which is dominated by the second hot (SH) and third hot (TH) bands of the main CO 2 isotopologue (hereafter 626).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Evidence of a significant rotational non-LTE effect in the CO<sub>2</sub> 4.3 µm PFS-MEX limb spectra

Kutepov

Rezac

2017

Atmos. Meas. Tech.

View full text Add to dashboard Cite

Abstract. Since January 2004, the planetary Fourier spectrometer (PFS) on board the Mars Express satellite has been recording near-infrared limb spectra of high quality up to the tangent altitudes ≈ 150 km, with potential information on density and thermal structure of the upper Martian atmosphere. We present first results of our modeling of the PFS short wavelength channel (SWC) daytime limb spectra for the altitude region above 90 km. We applied a ro-vibrational non-LTE model based on the stellar astrophysics technique of accelerated lambda iteration (ALI) to solve the multispecies and multi-level CO 2 problem in the Martian atmosphere. We show that the long-standing discrepancy between observed and calculated spectra in the cores and wings of 4.3 µm region is explained by the non-thermal rotational distribution of molecules in the upper vibrational states 10011 and 10012 of the CO 2 main isotope second hot (SH) bands above 90 km altitude. The redistribution of SH band intensities from band branch cores into their wings is caused (a) by intensive production of the CO 2 molecules in rotational states with j > 30 due to the absorption of solar radiation in optically thin wings of 2.7 µm bands and (b) by a short radiative lifetime of excited molecules, which is insufficient at altitudes above 90 km for collisions to maintain rotation of excited molecules thermalized. Implications for developing operational algorithms for massive processing of PFS and other instrument limb observations are discussed.

show abstract

Section: Discussionsupporting

confidence: 59%

Section: Rotational Lte and Non-ltementioning

confidence: 75%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evidence of a significant rotational non-LTE effect in the CO<sub>2</sub> 4.3 µm PFS-MEX limb spectra

Kutepov

Rezac

2017

Atmos. Meas. Tech.

View full text Add to dashboard Cite

show abstract

“…These large intensities can only be explained by invoking non-LTE effects, e.g., species that are pumped by solar radiation near 3.3 m and then fluoresce [López-Puertas and Taylor, 2001;García-Comas et al, 2011]. Without that pumping, the emission at the cold typical temperatures of Titan's upper atmosphere, 150 K, would be several orders of magnitude weaker.…”

Section: The Measurementsmentioning

confidence: 99%

“…[7] The observed atmospheric limb emission near 3.3 m at daytime is very strong (see Figure 1), and the measurements have a reasonably good signal-to-noise ratio ( 2 for the co-added integrated spectra) up to about 1250 km above Titan's surface. These large intensities can only be explained by invoking non-LTE effects, e.g., species that are pumped by solar radiation near 3.3 m and then fluoresce [López-Puertas and Taylor, 2001;García-Comas et al, 2011]. Without that pumping, the emission at the cold typical temperatures of Titan's upper atmosphere, 150 K, would be several orders of magnitude weaker.…”

Section: The Measurementsmentioning

confidence: 99%

An unidentified emission in Titan's upper atmosphere

Dinelli

López‐Puertas

Adriani

et al. 2013

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

[1] We have analyzed limb daytime observations of Titan's upper atmosphere at 3.3 m, acquired by the visual-infrared mapping spectrometer (VIMS) on Cassini. They were previously studied by García-Comas et al. (2011) to derive CH 4 densities. Here, we report an unidentified emission peaking around 3.28 m, hidden under the methane R branch. This emission is very strong, with intensity comparable to the CH 4 bands located in the same spectral region. It presents a maximum at about 950 km and extends from 600 km up to 1250 km. It is definitely pumped by solar radiation since it vanishes at night. Our analysis shows that neither methane nor the major hydrocarbon compounds already discovered in Titan's upper atmosphere are responsible for it. We have discarded many other potential candidates and suggest that the unidentified emission might be caused by aromatic compounds. Citation:

show abstract

CO₂ non‐LTE limb emissions in Mars' atmosphere as observed by OMEGA/Mars Express

et al. 2016

Self Cite

View full text Add to dashboard Cite

We report on daytime limb observations of Mars upper atmosphere acquired by the OMEGA instrument on board the European spacecraft Mars Express. The strong emission observed at 4.3 μm is interpreted as due to CO 2 fluorescence of solar radiation and is detected at a tangent altitude in between 60 and 110 km. The main value of OMEGA observations is that they provide simultaneously spectral information and good spatial sampling of the CO 2 emission. In this study we analyzed 98 dayside limb observations spanning over more than 3 Martian years, with a very good latitudinal and longitudinal coverage. Thanks to the precise altitude sounding capabilities of OMEGA, we extracted vertical profiles of the non-local thermodynamic equilibrium (non-LTE) emission at each wavelength and we studied their dependence on several geophysical parameters, such as the solar illumination and the tangent altitude. The dependence of the non-LTE emission on solar zenith angle and altitude follows a similar behavior to that predicted by the non-LTE model. According to our non-LTE model, the tangent altitude of the peak of the CO 2 emission varies with the thermal structure, but the pressure level where the peak of the emission is found remains constant at ∼0.03 ± 0.01 Pa, . This non-LTE model prediction has been corroborated by comparing SPICAM and OMEGA observations. We have shown that the seasonal variations of the altitude of constant pressure levels in SPICAM stellar occultation retrievals correlate well with the variations of the OMEGA peak emission altitudes, although the exact pressure level cannot be defined with the spectroscopy for the investigation of the characteristics of the atmosphere of Venus (SPICAM) nighttime data. Thus, observed changes in the altitude of the peak emission provide us information on the altitude of the 0.03 Pa pressure level. Since the pressure at a given altitude is dictated by the thermal structure below, the tangent altitude of the peak emission represents then an important piece of information of the atmosphere, of great value for validating general circulation models. We thus compared the altitude of OMEGA peak emission with the altitude of the 0.03 Pa level predicted by the Laboratoire de météorologie dynamique (LMD)-Mars global circulation model and found that the peak emission altitudes from OMEGA present a much larger variability than the tangent altitude of the 0.03 Pa level predicted by the general circulation model. This variability could be possibly due to unresolved atmospheric waves. Further studies using this strong CO 2 limb emission data are proposed. Key Points:• We analyzed 3 Martian years of CO 2 fluorescence emission in Mars' upper atmosphere • Observations are mainly affected by solar illumination conditions and the altitude of the emission • According to non-LTE model, the peak of the emission occurs at a constant pressure level of 0.03 Pa

show abstract

Modeling the atmospheric limb emission of CO2 at 4.3 μm in the terrestrial planets

Cited by 22 publications

References 22 publications

Evidence of a significant rotational non-LTE effect in the CO<sub>2</sub> 4.3 µm PFS-MEX limb spectra

Evidence of a significant rotational non-LTE effect in the CO<sub>2</sub> 4.3 µm PFS-MEX limb spectra

An unidentified emission in Titan's upper atmosphere

CO₂ non‐LTE limb emissions in Mars' atmosphere as observed by OMEGA/Mars Express

Contact Info

Product

Resources

About

Modeling the atmospheric limb emission of CO2 at 4.3 μm in the terrestrial planets

Cited by 22 publications

References 22 publications

Evidence of a significant rotational non-LTE effect in the CO&lt;sub&gt;2&lt;/sub&gt; 4.3 µm PFS-MEX limb spectra

Evidence of a significant rotational non-LTE effect in the CO&lt;sub&gt;2&lt;/sub&gt; 4.3 µm PFS-MEX limb spectra

An unidentified emission in Titan's upper atmosphere

CO2 non‐LTE limb emissions in Mars' atmosphere as observed by OMEGA/Mars Express

Contact Info

Product

Resources

About

Evidence of a significant rotational non-LTE effect in the CO<sub>2</sub> 4.3 µm PFS-MEX limb spectra

Evidence of a significant rotational non-LTE effect in the CO<sub>2</sub> 4.3 µm PFS-MEX limb spectra

CO₂ non‐LTE limb emissions in Mars' atmosphere as observed by OMEGA/Mars Express