H₂, He, and CO₂ Pressure-induced Parameters for the HITRAN Database. II. Line Lists of CO₂, N₂O, CO, SO₂, OH, OCS, H₂CO, HCN, PH₃, H₂S, and GeH₄

Abstract

In recent years, extended efforts have been made to increase the potential for modeling and interpreting the spectra of planetary atmospheres using the HITRAN database. A significant objective is to provide broadening parameters due to the ambient pressure of He, H2, and CO2 gases. Since hydrogen and helium are the main constituents in the atmospheres of gas giants, and carbon dioxide dominates the atmospheres of many rocky planets, these spectroscopic data are essential for radiative transfer models dedicated to planetary atmospheres. In HITRAN2016, the He-, H2- and CO2-broadening parameters and their temperature dependencies, and in some cases pressure-induced shifts, were added to the line lists of CO, SO2, NH3, HF, HCl, OCS, and C2H2. This work describes a further expansion introduced in the HITRAN2020 edition. In particular, relevant data for the line lists of CO2, N2O, OH, H2CO, HCN, PH3, H2S, and GeH4 were added, while those for CO, SO2, and OCS were revised. The new data are based on the semiempirical models constructed on available and validated experimental measurements and theoretical predictions. These models strongly depend on the extent and quality of the available data. The paper explains how to use the online interface or the HITRAN Application Programming Interface (HAPI) to retrieve these data from the database. Examples of calculating a molecule’s spectra in a mixture of buffer-gases using HAPI are also provided. We also provide a set of Python codes allowing one to populate any line list of corresponding molecules with relevant broadening parameters.

Origin and extent of the opacity challenge for atmospheric retrievals of WASP-39 b

“…The vast majority of them will showcase the CO 2 4.3-µm absorption feature broadened in large part by H 2 , the domi-nant atmospheric constituent of puffy atmospheres. Yet, the knowledge available for the CO 2 -H 2 system is very limited (Table 7 of Tan et al (2022)). Only extremely sparse measurements exist (Padmanabhan et al 2014;Hanson & Whitty 2014), which were used to scale a fairly complete dataset of air-broadened half-widths of CO 2 lines (Hashemi et al 2020) in HITRAN (Gordon et al 2022)-see Figure 1.…”

“…a) The sparse data for the CO 2 -H 2 system.Here, experimentally measured half-widths(Padmanabhan et al 2014;Hanson & Whitty 2014) do not provide sufficient coverage for populating the HITRAN database(Gordon et al 2022). The CO 2 -air broadening parameters in HITRAN have therefore been scaled to the measurement ofHanson & Whitty (2014) to retain rotational structure(Tan et al 2022), even though rotational dependence is not expected to be exactly the same. b) The effect of temperature dependence.…”

Origin and Extent of the Opacity Challenge for Atmospheric Retrievals of WASP-39 b

“…Here, experimentally measured halfwidths (Hanson & Whitty 2014;Padmanabhan et al 2014) do not provide sufficient coverage for populating the HITRAN database (Gordon et al 2022). The CO 2 -air-broadening parameters in HITRAN have therefore been scaled to the measurement of Hanson & Whitty (2014) to retain rotational structure (Tan et al 2022), even though rotational dependence is not expected to be exactly the same. (b) The effect of temperature dependence.…”

“…The vast majority of them will showcase the CO 2 4.3 μm absorption feature broadened in large part by H 2 , the dominant atmospheric constituent of puffy atmospheres. Yet, the knowledge available for the CO 2 -H 2 system is very limited (Table 7 of Tan et al 2022). Only extremely sparse measurements exist (Hanson & Whitty 2014;Padmanabhan et al 2014), which were used to scale a fairly complete data set of air-broadened half-widths of CO 2 lines (Hashemi et al 2020) in HITRAN (Gordon et al 2022)-see Figure 1.…”

Precision spectroscopy of molecular hydrogen

“…Laboratory-measured spectral data of the hydrogen molecule, including transition frequencies, intensities, and related temperature-/pressure-dependent spectroscopic parameters, are the basis for modeling the planetary atmospheres. 10,11 Spectral analysis based on these spectroscopic parameters led to the previous discovery that hydrogen is the main component of the atmospheres of Jupiter, Saturn, and other planets, 12,13 and more accurate data is demanded to improve the analysis.…”