Solution of the non-LTE problem for molecular gas in planetary atmospheres: superiority of accelerated lambda iteration

Kutepov, A. A.; Gusev, Oleg; Ogibalov, V. P.

doi:10.1016/s0022-4073(97)00167-2

Cited by 65 publications

(51 citation statements)

References 21 publications

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“…Our model atmospheres extend to 10 bars, where nonlocal Ϫ10 thermodynamic equilibrium (non-LTE) effects might occur (Kutepov et al 1998). However, if we truncate our calculations to 10 bars, we obtain a maximum error of ∼0.02% at 30 mm…”

Section: ϫ10mentioning

confidence: 92%

Infrared Transmission Spectra for Extrasolar Giant Planets

Tinetti¹,

Liang²,

Vidal‐Madjar³

et al. 2006

ApJ

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Among the hot Jupiters known to date that transit their parent stars, the two best candidates to be observed with transmission spectroscopy in the mid-infrared (MIR) are HD 189733b and HD 209458b, due to their combined characteristics of planetary density, orbital parameters, and parent star distance and brightness. Here we simulate transmission spectra of these two planets during their primary transit in the MIR, and we present sensitivity studies of the spectra to the changes of atmospheric thermal properties, molecular abundances, and C/O ratios. Our model predicts that the dominant species absorbing in the MIR on hot Jupiters are water vapor and carbon monoxide, and their relative abundances are determined by the C/O ratio. Since the temperature profile plays a secondary role in the transmission spectra of hot Jupiters compared to molecular abundances, future primary transit observations in the MIR of those objects might offer insight on extrasolar giant planet atmospheric chemistry. We find here that the absorption features caused by water vapor and carbon monoxide in a cloud-free atmosphere are deep enough to be observable by the present and future generation of space-based observatories, such as Spitzer Space Telescope and James Webb Space Telescope. We discuss our results in light of the capabilities of these telescopes.

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Section: ϫ10mentioning

confidence: 92%

Infrared Transmission Spectra for Extrasolar Giant Planets

Tinetti¹,

Liang²,

Vidal‐Madjar³

et al. 2006

ApJ

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“…Most of the calculations performed in this work were made using the ALI-ARMS computer code (see Kutepov et al, 1998;Gusev and Kutepov, 2003; and references therein) that solves the multi-level problem using the Accelerated Lambda Iteration (ALI) technique developed for calculating non-LTE populations of atomic and ionic levels in stellar atmospheres (Rybicki and Hummer, 1991). The code iteratively solves a set of statistical equilibrium equations and the radiative transfer equations.…”

Section: Ali-arms Research Codementioning

confidence: 99%

Daytime SABER/TIMED observations of water vapor in the mesosphere: retrieval approach and first results

et al. 2009

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Abstract. This paper describes a methodology for water vapor retrieval in the mesosphere-lower thermosphere (MLT) using 6.6 µm daytime broadband emissions measured by SABER, the limb scanning infrared radiometer on board the TIMED satellite. Particular attention is given to accounting for the non-local thermodynamic equilibrium (non-LTE) nature of the H 2 O 6.6 µm emission in the MLT. The non-LTE H 2 O(ν 2 ) vibrational level populations responsible for this emission depend on energy exchange processes within the H 2 O vibrational system as well as on interactions with vibrationally excited states of the O 2 , N 2 , and CO 2 molecules. The rate coefficients of these processes are known with large uncertainties that undermines the reliability of the H 2 O retrieval procedure. We developed a methodology of finding the optimal set of rate coefficients using the nearly coincidental solar occultation H 2 O density measurements by the ACE-FTS satellite and relying on the better signal-to-noise ratio of SABER daytime 6.6 µm measurements. From this comparison we derived an update to the rate coefficients of the three most important processes that affect the H 2 O(ν 2 ) populations in the MLT: a) the vibrational-vibrational (V-V) exchange between the H 2 O and O 2 molecules; b) the vibrationaltranslational (V-T) process of the O 2 (1) level quenching by collisions with atomic oxygen, and c) the V-T process of the H 2 O(010) level quenching by collisions with N 2 , O 2 , and O. Using the advantages of the daytime retrievals in the MLT, which are more stable and less susceptible to uncertainties Correspondence to: A. G. Feofilov (artem-feofilov@cua-nasa-gsfc.info) of the radiance coming from below, we demonstrate that applying the updated H 2 O non-LTE model to the SABER daytime radiances makes the retrieved H 2 O vertical profiles in 50-85 km region consistent with climatological data and model predictions. The H 2 O retrieval uncertainties in this approach are about 10% at and below 70 km, 20% at 80 km, and 30% at 85 km altitude.

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“…Both parts are calculated very efficiently with the non-LTE model of Kutepov et al [1998]. The multilevel non-LTE problem is solved using the Accelerated Lambda Iteration (ALI) technique [Rybicki and Hummer, 1991] and the radiative transfer is calculated line-by-line using the Feautrier method [Rybicki and Hummer, 1991].…”

Section: Non-lte O 3 Limb Radiances Modelingmentioning

confidence: 99%

Satellite observations of daytime and nighttime ozone in the mesosphere and lower thermosphere

et al. 2003

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[1] The global distribution of mesospheric and lower thermospheric ozone 9.6 mm infrared emissions was measured by the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) experiment during two Space Shuttle missions in November 1994 and August 1997. The radiances measured by CRISTA have been inverted to O 3 number densities in the 50-95 km range by using a nonlocal thermodynamic equilibrium model. A detailed sensitivity study of retrieved O 3 number densities has been carried out. The ozone abundance profiles show volume mixing ratios of 1-2 ppmv at the stratopause, 0.5 ppmv or less around 80 km, and typically 1 ppmv during daytime and 10 ppmv during nighttime at the secondary maximum. The agreement with other experiments is typically better than 25%. The global distribution of upper mesospheric ozone shows significant latitudinal gradients and an enhancement in the equatorial upper mesosphere. At the polar night terminator a third ozone maximum is observed. Three-dimensional model results indicate that the latitudinal gradients are significantly influenced by solar tides.

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Solution of the non-LTE problem for molecular gas in planetary atmospheres: superiority of accelerated lambda iteration

Cited by 65 publications

References 21 publications

Infrared Transmission Spectra for Extrasolar Giant Planets

Infrared Transmission Spectra for Extrasolar Giant Planets

Daytime SABER/TIMED observations of water vapor in the mesosphere: retrieval approach and first results

Satellite observations of daytime and nighttime ozone in the mesosphere and lower thermosphere

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