We review recent progress in the calculation of the global, high-temperature and accurate room-temperature linelists of various molecules relevant for the analysis of both Earth and exoplanet atmospheres and cool stars. These global line lists can be constructed based on progress in calculation of energy levels up to dissociation and the fitting of the molecular PESs to the experimental data close to dissociation. Sub-percent accuracy in the intensity of calculated absorption lines is achieved thanks to progress in ab initio electronic structure calculations which is aided by the possibility of characterizing their accuracy by the comparison with experimental intensities measured with sub-percent accuracy for some molecular lines. The advantage of variational calculations over experiment though is the ability to produce billions of lines covering all the isotopologues, which is clearly impossible for the experimental observations. Atmospherically and astrophysically important molecules such as H₂O, CO₂, CO and H₃⁺ will be considered together with some examples of the other molecules.

The ability to calculate molecular line intensities from first principles plays an increasingly important role in populating line-by-line spectroscopic databases because of its generality and extensibility to various isotopologues, spectral ranges and temperature conditions. Such calculations require a spectroscopically determined potential energy surface, and an accurate dipole moment surface that can be either fully ab initio E. Zak et al., J. Quant. Spectrosc. Radiat. Transf. 177, (2016) 31.Huang et al., J. Quant. Spectrosc. Radiat. Transf. 130, (2013) 134. or an effective quantity based on fits to measurements Tashkun et al., J. Quant. Spectrosc. Radiat. Transf. 152, (2015) 45.. Following our recent work where we used high−precision measurements of intensities in the (30013 00001) band of ^12C^16O_2 to bound the uncertainty of calculated line lists Polyansky et al., Phys Rev. Lett. 114, (2015) 243001., here we carry out high-precision, frequency-stabilized cavity ring-down spectroscopy measurements in the R-branch of the ¹²C¹⁶O₂ (20012 →00001) band from J = 16 to 52. Gas samples consisted of 50 μmol mol⁻¹ or 100 μmol mol⁻¹ of nitrogen-broadened carbon dioxide with gravimetrically determined SI-traceable molar composition. We demonstrate relative measurement precision (Type A) at the 0.15 % level and estimate systematic (Type B) uncertainty contributions in % of: isotopic abundance 0.01; sample density, 0.016; cavity free spectral rang,e 0.03; line shape, 0.05; line interferences, 0.05; and carbon dioxide molar fraction, 0.06. Combined in quadrature, these components yield a relative standard uncertainty in measured line intensity less than 0.2 % for most observed transitions. These intensities differ by more than 2 % from those measured by Fourier transform spectroscopy and archived in HITRAN 2012 but differ by less than 0.5 % with the calculations of Zak et al.

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E. Zak et al., J. Quant. Spectrosc. Radiat. Transf. 177, (2016) 31.

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Tashkun et al., J. Quant. Spectrosc. Radiat. Transf. 152, (2015) 45.\end Polyansky et al., Phys Rev. Lett. 114, (2015) 243001.

With inherent simplicity, mutual phase coherence, and a high degree of user control, electro-optic frequency combs are amenable to both dual-comb spectroscopyI. Coddington et al., Optica 3, 414 (2016)nd cavity-enhanced comb spectroscopy.B. Bernhardt et al., Nat. Photonics 4, 55 (2010)his combination of fast, multiplexed spectroscopy, with an effective absorption pathlength > 1 km, is used here to perform line-by-line metrology of the gas-phase absorption spectra of CO₂, H₂O, and N₂O in the near-infrared. We report absolute transition frequency with precision better than 1 MHz in 1 s of spectral acquisition per transition using a comb with an instantaneous optical bandwidth of 6 GHz, tunable over the entire 6240-6370 cm⁻¹range. A full model for the electric field transmitted through the enhancement cavity (even in the presence of strong molecular absorption and dispersion) will be discussed.

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I. Coddington et al., Optica 3, 414 (2016)a B. Bernhardt et al., Nat. Photonics 4, 55 (2010)T

A new experimental line parameter list of water vapor absorption lines in the spectral ranges 1850 - 2280 cm and 2390 - 4000 cm is presented. The line list is based on the analysis of several transmittance spectra measured using a Bruker IFS 125 HR high resolution Fourier transform spectrometer. A total of 54 measurements of pure water and water/air-mixtures at 296 K as well as water/air-mixtures at high and low temperatures were performed. A multispectrum fitting approach was used applying a quadratic speed-dependent hard collision line shape model in the Hartmann-Tran implementationN.H. Ngo et al. JQSRT 129, 89-100 (2013) doi:10.1016/j.jqsrt.2013.05.034; JQSRT 134, 105 (2014) doi:10.1016/j.jqsrt.2013.10.016.H. Tran et al. JQSRT 129, 199-203 (2013) doi:10.1016/j.jqsrt.2013.06.015; JQSRT 134, 104 (2014) doi:10.1016/j.jqsrt.2013.10.015. extended to account for line mixing in the Rosenkranz approximation in order to retrieve line positions, intensities, self- and air-broadening parameters, their speed-dependence, self- and air-shifts as well as line mixing and in some cases collisional narrowing parameters. Additionally, temperature dependence parameters for widths, shifts and in a few cases line mixing were retrieved. For every parameter an extensive error estimation calculation was performed identifying and specifying systematic error sources. The resulting parameters are compared to the databases HITRAN12L.S. Rothman et al. JQSRT 130, 4-50 (2013) doi:10.1016/j.jqsrt.2013.07.002.nd GEISA15N. Jacquinet-Husson et al. JMS 112, 2395-2445 (2016) doi:10.1016/j.jms.2016.06.007.s well as experimental values. For intensities, a detailed comparison to results of recent ab initio calculations performed at University College London was done showing an agreement within 2 % for a majority of the data. However, for some bands there are systematic deviations attributed to ab initio calculation errors.

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N.H. Ngo et al. JQSRT 129, 89-100 (2013) doi:10.1016/j.jqsrt.2013.05.034; JQSRT 134, 105 (2014) doi:10.1016/j.jqsrt.2013.10.016.

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L.S. Rothman et al. JQSRT 130, 4-50 (2013) doi:10.1016/j.jqsrt.2013.07.002.a N. Jacquinet-Husson et al. JMS 112, 2395-2445 (2016) doi:10.1016/j.jms.2016.06.007.a

We report preliminary measurements on the temperature dependence of H₂-broadening of CH₄ in the near infrared at temperatures between 100 and 370 K. In support of the Jovian and exoplanet atmospheric remote sensing in the near infrared, we have measured the temperature dependence of H₂-broadened half width and pressure shift coefficients of CH₄, both of which are known to be rotational quantum number dependent. We studied both cold and hot CH₄ in the atmospheric K band ( 2.2 μm) with the focus on a) weaker lines in the ν₂+ν₃ band at low temperatures for cold giant planets and b) stronger lines in the ν₃+ν₄ band at elevated temperatures for extra-solar planets (e.g., hot-Jupiters). Three custom-built gas absorption cells (two cold and one hot) were used to obtain the spectra of CH₄ and H₂ mixtures at temperatures between 100 and 370 K. We will discuss our on-going spectrum analysis for a few select J manifolds and provide comparisons with published values, which are available only at room temperature.

We present a new spectroscopic potential energy surface (PES) for ¹⁴NH₃, produced by refining a high accuracy ab initio PESOleg L. Polyansky, Roman I. Ovsyannikov, Aleksandra A. Kyuberis, Lorenzo Lodi, Jonathan Tennyson, Andrey Yachmenev, Sergei N. Yurchenko, Nikolai F. Zobov, J. Mol. Spec., 327 (2016) 21-30o experimental energy levels taken predominantly from MARVELAfaf R. Al Derzia, Tibor Furtenbacher, Jonathan Tennyson, Sergei N. Yurchenko, Attila G. Császár, J. Quant. Spectrosc. Rad. Trans., 161 (2015) 117-130 The PES reproduces 1722 matched J=0-8 experimental energies with a root-mean-square error of 0.035 cm-1 under 6000 cm⁻¹ and 0.059 under 7200 cm⁻¹. In conjunction with a new DMS calculated using multi reference configuration interaction (MRCI) and H=aug-cc-pVQZ, N=aug-cc-pWCVQZ basis sets, an infrared (IR) line list has been computed which is suitable for use up to 2000 K. The line list is used to assign experimental lines in the 7500 - 10,500 cm⁻¹ region and previously unassigned lines in HITRAN in the 6000-7000 cm⁻¹ region.

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Oleg L. Polyansky, Roman I. Ovsyannikov, Aleksandra A. Kyuberis, Lorenzo Lodi, Jonathan Tennyson, Andrey Yachmenev, Sergei N. Yurchenko, Nikolai F. Zobov, J. Mol. Spec., 327 (2016) 21-30t Afaf R. Al Derzia, Tibor Furtenbacher, Jonathan Tennyson, Sergei N. Yurchenko, Attila G. Császár, J. Quant. Spectrosc. Rad. Trans., 161 (2015) 117-130.

The OH radical is observed in cool stars, interstellar medium, comets and is an important oxidizer in the Earth’s atmosphere. A new linelist for the (A ²Σ⁺-X ²Π) transition of OH has been calculated. The line positions have been obtained from the literature and the line intensities were calculated from a new ab initio transition dipole moment function obtained from Molpro quantum chemistry package. This dipole moment function along with the RKR potentials have been used in LeRoy’s LEVEL program in order to calculate transition dipole matrix elements. These matrix elements are transformed from Hund’s case (b) to Hund’s case (a) as required for Western’s PGopher program. The linelist was calculated with PGopher.

The HITRAN2016I. E. Gordon, L. S. Rothman, C. Hill, R. V. Kochanov, Y. Tan, et al. The HITRAN2016 Molecular Spectroscopic Database. JQSRT 2017;submitted.atabase is now officially releasedMany spectroscopists and atmospheric scientists worldwide have contributed data to the database or provided invaluable validations. Plethora of experimental and theoretical molecular spectroscopic data were collected, evaluated and vetted before compiling the new edition of the database. The database is now distributed through the dynamic user interface HITRANonline (available at www.hitran.org) which offers many flexible options for browsing and downloading the dataC. Hill, I. E. Gordon, R. V. Kochanov, L. Barrett, J.S. Wilzewski, L.S. Rothman, JQSRT. 177 (2016) 4-–14 In addition HITRAN Application Programming Interface (HAPI) offers modern ways to download the HITRAN data and use it to carry out sophisticated calculationsR.V. Kochanov, I. E. Gordon, L. S. Rothman, P. Wcislo, C. Hill, J. S. Wilzewski, JQSRT. 177 (2016) 15–-30. The line-by-line lists for almost all of the 47 HITRAN molecules were updated in comparison with the previous compilation (HITRAN2012L. S. Rothman, I. E. Gordon et al. The HITRAN2012 Molecular Spectroscopic Database. JQSRT, 113 (2013) 4-50.. Some of the most important updates for major atmospheric absorbers, such as H₂O, CO₂, O₃, N₂O, CO, CH₄, and O₂, will be presented in this talk, while the trace gases will be presented in the next talk by Y. Tan. The HITRAN2016 database now provides alternative line-shape representations for a number of molecules, as well as broadening by gases dominant in planetary atmospheres. In addition, substantial extension and improvement of cross-section data is featured, which will be described in a dedicated talk by R. V. Kochanov. The new edition of the database is a substantial step forward to improve retrievals of the planetary atmospheric constituents in comparison with previous editions, while offering new ways of working with the data.
The HITRAN database is supported by the NASA AURA and PDART program grants NNX14AI55G and NNX16AG51G.

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I. E. Gordon, L. S. Rothman, C. Hill, R. V. Kochanov, Y. Tan, et al. The HITRAN2016 Molecular Spectroscopic Database. JQSRT 2017;submitted.d Many spectroscopists and atmospheric scientists worldwide have contributed data to the database or provided invaluable validations.. C. Hill, I. E. Gordon, R. V. Kochanov, L. Barrett, J.S. Wilzewski, L.S. Rothman, JQSRT. 177 (2016) 4-–14. R.V. Kochanov, I. E. Gordon, L. S. Rothman, P. Wcislo, C. Hill, J. S. Wilzewski, JQSRT. 177 (2016) 15–-30.. L. S. Rothman, I. E. Gordon et al. The HITRAN2012 Molecular Spectroscopic Database. JQSRT, 113 (2013) 4-50.)

The 2016 edition of HITRAN database The HITRAN database is supported by the NASA AURA program grant NNX14AI55G and NASA PDART grant NNX16AG51G.s available now I. E. Gordon, L. S. Rothman, et al., J Quant Spectrosc Radiat Transf 2017; submitted. This new edition of the database takes advantage of the new structure and can be accessed through HITRANonline (www.hitran.org) Hill C, et al., J Quant Spectrosc Radiat Transf 2013;130:51–61. The line-by-line lists for almost all of the trace atmospheric species were updated in comparison with the previous edition HITRAN2012. These extended update covers not only updating few transitions of the certain molecules, but also complete replacements of the whole line lists, and as well as introduction of new spectroscopic parameters for non-Voigt line shape. The new line lists for NH₃, HNO₃, OCS, HCN, CH₃Cl, C₂H₂, C₂H₆, PH₃, C₂H₄, CH₃CN, CF₄, C₄H₂, and SO₃ feature substantial expansion of the spectral and dynamic ranges in addition of the improved accuracy of the parameters for already existing lines. A semi-empirical procedure was developed to update the air-broadening and self-broadening coefficients of N₂O, SO₂, NH₃, CH₃Cl, H₂S, and HO₂. We draw particular attention to flaws in the commonly used expression n_air=0.79n_N2+0.21n_O2 to determine the air-broadening temperature dependence exponent in the power law from those for nitrogen and oxygen broadening. A more meaningful approach will be presented. The semi-empirical line width, pressure shifts and temperature-dependence exponents of CO, NH₃, HF, HCl, OCS, C₂H₂, SO₂ perturbed by H₂, He, and CO₂ have been added to the database based on the algorithm described in Wilzewski et al.Wilzewski JS,et al., J Quant Spectrosc Radiat Transf 2016;168:193–206. The new spectroscopic parameters for HT profile were implemented into the database for hydrogen moleculeWcisło P, et al., J Quant Spectrosc Radiat Transf 2016;177:75–91.

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The HITRAN database is supported by the NASA AURA program grant NNX14AI55G and NASA PDART grant NNX16AG51G.i I. E. Gordon, L. S. Rothman, et al., J Quant Spectrosc Radiat Transf 2017; submitted.. Hill C, et al., J Quant Spectrosc Radiat Transf 2013;130:51–61.. Wilzewski JS,et al., J Quant Spectrosc Radiat Transf 2016;168:193–206.. Wcisło P, et al., J Quant Spectrosc Radiat Transf 2016;177:75–91..

In this talk, an overview is given for the recent absorption cross-section update in the new HITRAN2016 spectroscopic database release. The updated cross-sections include data for around 330 molecules for applications in atmospheric remote sensing, industrial pollution tracking, climate change monitoring, remote sensing, spectral calibration, and more. These cross-sections come from high-resolution laboratory observations, predominantly using FT-IR technique. The update largely relies on spectra from the PNNL quantitative spectroscopic database and the Hodnebrog et al. (Rev Geophys 2013) compilation, but also on other recently published data for many applications such as biomass burning detection, remote sensing in the UTLS, environment monitoring, etc. (references will be given in the talk). The described data are available via the HITRANonline websiteHill C. et al. JQSRT 2016;177:4–14.nd HITRAN Application Programing Interface (HAPI)Kochanov RV et al.JQSRT 2016;177:15–30. This work is supported by NASA AURA (NNX14AI55G) and NASA PDART (NNX16AG51G) grants.

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Hill C. et al. JQSRT 2016;177:4–14.a Kochanov RV et al.JQSRT 2016;177:15–30..

The NH radical is important in astronomy as it is observed in cool stars and the interstellar medium. A new line list for A³Π - X³Σ⁻ electronic transition has been prepared using line positions from the literature and calculated line intensities. High level ab-initio calculations are performed with Molpro to obtain the A-X transition dipole moment function. Potential energy curves and the line strengths are calculated by Le Roy’s RKR and LEVEL programs. Line intensities and Einstein A values were calculated with Western’s PGOPHER program after converting Hund’s case (b) output of LEVEL to Hund’s case (a) input needed for PGOPHER.

Alkali-containing molecules are expected to be present in the atmospheres of exoplanets such as rocky super-EarthsPhil. Trans. R. Soc. A 372, 20130087 (2014)s well as in cool dwarf stars.Astrophys. J. 519, 793 (1999)ine lists for LiF and LiCl in their X¹Σ⁺ ground states have been calculated using LeRoy’s LEVEL program.J. Quant. Spectrosc. Radiat. Transfer 186, 167 (2017)he potential energy functions, including the effects of the breakdown of the Born-Oppenheimer approximation, are obtained by direct fitting the experimental infrared vibration-rotation and microwave pure rotation data with extended Morse oscillator potentials using LeRoy’s dPotFit program.J. Quant. Spectrosc. Radiat. Transfer 186, 179 (2017)he transition dipole matrix elements and line intensities were obtained with LEVEL using a dipole moment function from a high level ab initio calculation.

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Phil. Trans. R. Soc. A 372, 20130087 (2014)a Astrophys. J. 519, 793 (1999)L J. Quant. Spectrosc. Radiat. Transfer 186, 167 (2017)T J. Quant. Spectrosc. Radiat. Transfer 186, 179 (2017)T