Total internal partition sums for 166 isotopologues of 51 molecules important in planetary atmospheres: Application to HITRAN2016 and beyond

Gamache, Robert R.; Roller, Christopher; Lopes, Eldon; Gordon, Iouli E.; Rothman, Laurence S.; Polyansky, Oleg L.; Zobov, Nikolai F.; Kyuberis, Aleksandra A.; Tennyson, Jonathan; Yurchenko, Sergei N.; Császár, Attila G.; Furtenbacher, Tibor; Huang, Xinchuan; Schwenke, David W.; Lee, Timothy J.; Drouin, Brian J.; Tashkun, S.A.; Perevalov, V.I.; Kochanov, Roman V.

doi:10.1016/j.jqsrt.2017.03.045

Cited by 142 publications

(101 citation statements)

References 78 publications

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“…The partition function can easily be computed from the ExoMol states file (Tennyson Figure 3. The 12 C 2 H 2 partition function up to 3000 K; comparing the states from the aCeTY line list (this work) against that computed using TIPS (Gamache et al 2017), the coefficients of Irwin (1981), and using energies extracted from ASD-1000 .…”

Section: Results: the Acety Line Listmentioning

confidence: 99%

ExoMol molecular line lists – XXXVII. Spectra of acetylene

Chubb

Tennyson

Yurchenko

2020

Monthly Notices of the Royal Astronomical Society

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A new ro-vibrational line list for the ground electronic state of the main isotopologue of acetylene, 12 C 2 H 2 , is computed as part of the ExoMol project. The aCeTY line list covers the transition wavenumbers up to 10 000 cm −1 (λ > 1 µm), with lower and upper energy levels up to 12 000 cm −1 and 22 000 cm −1 considered, respectively. The calculations are performed up to a maximum value for the vibrational angular momentum, K max = L max = 16, and maximum rotational angular momentum, J = 99. Higher values of J were not within the specified wavenumber window. The aCeTY line list is considered to be complete up to 2200 K, making it suitable for use in characterising high-temperature exoplanet or cool stellar atmospheres. Einstein-A coefficients, which can directly be used to calculate intensities at a particular temperature, are computed for 4.3 billion (4 347 381 911) transitions between 5 million (5 160 803) energy levels. We make comparisons against other available data for 12 C 2 H 2 , and demonstrate this to be the most complete line list available. The line list is available in electronic form from the online CDS and ExoMol databases.

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Section: Results: the Acety Line Listmentioning

confidence: 99%

ExoMol molecular line lists – XXXVII. Spectra of acetylene

Chubb

Tennyson

Yurchenko

2020

Monthly Notices of the Royal Astronomical Society

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“…Rotational-vibrational absorption coefficients are calculated from line lists using our line-by-line absorption coefficients code (LBLABC, Crisp 1997). Here we have updated the partition functions (Gamache et al 2017) and draw from the HITRAN2016 line list (Gordon et al 2017), which are appropriate for the temperatures and pressures in these terrestrial atmospheres. We consider isotopic fractionation δD of 10-100, and δ 18 O of 2-100, depending on the model atmosphere environment (see §2.5), and adjust the abundances of the isotopologues accordingly (see §2.2).…”

Section: Radiative Transfermentioning

confidence: 99%

Observing Isotopologue Bands in Terrestrial Exoplanet Atmospheres with the James Webb Space Telescope: Implications for Identifying Past Atmospheric and Ocean Loss

Lincowski

Lustig‐Yaeger

Meadows

2019

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Terrestrial planets orbiting M dwarfs may soon be observed with the James Webb Space Telescope (JWST) to characterize their atmospheric composition and search for signs of habitability or life. These planets may undergo significant atmospheric and ocean loss due to the superluminous pre-main-sequence phase of their host stars, which may leave behind abiotically-generated oxygen, a false positive for the detection of life. Determining if ocean loss has occurred will help assess potential habitability and whether or not any O 2 detected is biogenic. In the solar system, differences in isotopic abundances have been used to infer the history of ocean loss and atmospheric escape (e.g. Venus, Mars). We find that isotopologue measurements using transit transmission spectra of terrestrial planets around late-type M dwarfs like TRAPPIST-1 may be possible with JWST, if the escape mechanisms and resulting isotopic fractionation were similar to Venus. We present analyses of post-ocean-loss O 2 -and CO 2 -dominated atmospheres, containing a range of trace gas abundances. Isotopologue bands are likely detectable throughout the near-infrared (1-8 µm), especially 3-4 µm, although not in CO 2 -dominated atmospheres. For Venus-like D/H ratios 100 times that of Earth, TRAPPIST-1 b transit signals of up to 79 ppm are possible by observing HDO. Similarly, 18 O/ 16 O ratios 100 times that of Earth produce signals at up to 94 ppm. Detection at S/N=5 may be attained on these bands with as few as four to eleven transits, with optimal use of JWST NIRSpec Prism. Consequently, H 2 O and CO 2 isotopologues could be considered as indicators of past ocean loss and atmospheric escape for JWST observations of terrestrial planets around M dwarfs.

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“…For the line intensity, the temperature dependence is given by the total number of populated molecular states (the partition sum), which can be calculated numerically (Gamache et al, 2017), and the population of molecular energy levels corresponding to the transition. The latter is calculated from the energy of the lower level and the frequency of the corresponding transition.…”

Section: Absorption Model Parameterizationmentioning

confidence: 99%

“…Tretyakov (2016) within its review and expert assessment. The only exceptions are the uncertainty estimates for g a , g w , and 1 at 22 GHz taken from the more recent investigation of Koshelev et al (2018), and the uncertainty for n S , which has been 320 independently estimated within the 200-400 K temperature range as the maximal difference between numerical calculation of the partition sums at various temperatures published by Gamache et al (2017) (18) and 1.11(10) respectively for self and foreign coefficients). The uncertainties for V6 and V• are estimated such to overlap within uncertainty the values given by Koshelev et al (2011) based on laboratory measurements.…”

Section: Sensitivity To Water Vapor Parameters 310mentioning

confidence: 99%

“…Uncertainty of n S value for the 200-350 K temperature range was evaluated the same way as for water vapor lines, i.e. comparing partition sum calculations by Gamache et al (2017) and thus these fifteen lines are not further considered in the following analysis. For the remaining thirty-four lines (N from 1-to 33+), the uncertainty for line air-broadening, mixing, and mixing temperature-dependence coefficients is evaluated 370 through the full covariance matrices, so their treatment is postponed to Section 4.…”

Section: Sensitivity To Oxygen Parameters 340mentioning

confidence: 99%

See 1 more Smart Citation

Uncertainty of atmospheric microwave absorption model: impact on ground-based radiometer simulations and retrievals

Cimini¹,

Rosenkranz²,

Tretyakov³

et al. 2018

Preprint

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Abstract. This paper presents a general approach to quantify the absorption model uncertainty due to uncertainty in underlying spectroscopic parameters. The approach is applied to radiative transfer calculations in the 20-60 GHz range, which is commonly exploited for atmospheric sounding by microwave radiometer (MWR). The approach however is not limited to any frequency range, observing geometry, or particular instrument. In the considered frequency range, relevant uncertainties come from water vapor and oxygen spectroscopic parameters. The uncertainty of the following parameters is 15 found to dominate: (for water vapor) self and foreign continuum absorption coefficients, line broadening by dry air, line intensity, temperature-dependence exponent for foreign continuum absorption, and line shift-to-broadening ratio; (for oxygen) line intensity, line broadening by dry air, line mixing, temperature-dependence exponent for broadening, zerofrequency line broadening in air, temperature-dependence coefficient for line mixing. The full uncertainty covariance matrix is then computed for the set of spectroscopic parameters with significant impact. The impact of the spectroscopic parameter 20 uncertainty covariance matrix on simulated downwelling microwave brightness temperatures (T B ) in the 20-60 GHz range is calculated for six atmospheric climatology conditions. The uncertainty contribution to simulated T B ranges from 0.30 K (sub-Arctic winter) to 0.92 K (tropical) at 22.2 GHz, and from 2.73 K (tropical) to 3.31 K (sub-Arctic winter) at 52.28 GHz.The uncertainty contribution is nearly zero at 55-60 GHz frequencies. Finally, the impact of spectroscopic parameter uncertainty on ground-based MWR retrievals of temperature and humidity profiles is discussed. 25

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Total internal partition sums for 166 isotopologues of 51 molecules important in planetary atmospheres: Application to HITRAN2016 and beyond

Cited by 142 publications

References 78 publications

ExoMol molecular line lists – XXXVII. Spectra of acetylene

ExoMol molecular line lists – XXXVII. Spectra of acetylene

Observing Isotopologue Bands in Terrestrial Exoplanet Atmospheres with the James Webb Space Telescope: Implications for Identifying Past Atmospheric and Ocean Loss

Uncertainty of atmospheric microwave absorption model: impact on ground-based radiometer simulations and retrievals

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