HITRANonline

We are pleased to announce there are now over 36000 registered users of www.hitran.org

This is a reminder that the data currently provided on this site corresponds to the 2020 edition of the database, with some data updated as described in the "Update" section below. The HITRAN2024 edition will be released in the first half of 2025.

We are excited to announce a special issue celebrating over half a century of success of the HITRAN molecular spectroscopy database and the remarkable contributions of its long-term director, Dr. Laurence S. Rothman. This issue will feature the article describing the HITRAN2024 edition of the database, as well as other contributions describing cutting-edge research. We invite contributions that continue to push the boundaries of molecular spectroscopic research of atmospheric and astrophysical interest and celebrate HITRAN's legacy. The specific topics include:

1. New laboratory or theoretical spectroscopic data for the species of atmospheric or astrophysical importance.

2. Compilation of molecular spectroscopic databases.

3. Validation of spectroscopic parameters in atmospheric and astrophysical applications.

4. Database archiving, tools, and methodology.

All papers will have to meet the publication standards of JQSRT, and will be subject to the normal submission and refereeing process. The online submission to the special issue is already active and will close on May 1, 2025. To submit your manuscript, please go to the Journal of Quantitative Spectroscopy & Radiative Transfer (at https://www.sciencedirect.com/journal/journal-of-quantitative-spectroscopy-and-radiative-transfer ) and follow the procedures for manuscript submission. Please select VSI: HITRAN 2024 when you reach the “Article Type” step in the submission process.

Thanks to multiple requests, the water vapor continuum is making its debut in HITRAN. The MT_CKD (Mlawer-Tobin-Clough-Kneizys-Davies) Water Vapor Continuum Model provides absorption coefficients due to water vapor that should be added to the contributions calculated from the line-by-line water vapor transitions to obtain the total absorption due to water vapor. Description of the parametrization and other details can be found in Mlawer et al., JQSRT (2023)

https://hitran.org/mtckd/

The HITRAN support e-mail has been established and our team is ready for questions.

The carbon dioxide line list in HITEMP has been expanded and updated as described in Hargreaves et al. (2024). The line list is based on AI-3000K (Huang et al. 2023), an ab initio line list (with many line positions corrected based on semi-empirical energy levels) constructed for modeling high-temperature spectra of CO₂. Further empirical scaling of the intensities was introduced in this work, where appropriate.

The HITEMP line list implements a novel approach for "effective lines" to account for the contribution of billions of weak transitions, thus reducing the number of total lines required for accurate modeling by two orders of magnitude. The CO₂ HITEMP line list has been validated against experimental measurements up to 2000 K and further details are described in Hargreaves et al. (2024).

The new line list is available to download from https://hitran.org/hitemp/. Users will need to be logged in to download the HITEMP line lists.

The NO₂ line list has been updated throughout the 1000-5000 cm^-1 spectral region, based on the work of Perrin et al. (2021).

This update encompasses the addition of numerous hot bands and combination bands of ¹⁴N¹⁶O₂, along with improved spectral parameters for existing bands in the region. Furthermore, the ν₁+ν₃ and ν₁+2ν₂ bands of ¹⁵N¹⁶O₂ have been added.

The line list for acetylene has been updated and expanded for two spectral regions described below:

● Expansion of the 3.8 μm region (2400-2900 cm^-1) based on the works of Jacquemart et al. (2023a, 2023b, 2023c). This ΔP=4 region now includes 71 bands of ¹²C₂H₂ along with 11 bands of ¹²C¹³CH₂ and 6 bands of ¹²C₂HD.

● Addition of the Q-branch of the ν₁+ν₃+3ν₄ band of ¹²C₂H₂near 8330 cm^-1 from Jacquemart et al. (2022)

In addition, H₂, He and CO₂ broadening parameters (described by Wilzewski et al., 2016) have also been extended to newly added transitions.

Following the update of the CH₃CN, that was issued in January 2023, additional improvements have been introduced as follows:

1. The intensity distribution between some of the lines has been revised.

2. The Einstein-A coefficients for most of the lines have been recalculated.

3. The air-broadening and self-broadening half-widths and temperature dependencies have also been revised by adding data from semi-classical calculation of Dudaryonok et al. (2015a) and (2015b). Note that for air-broadening we now scale the N₂ values by multiplying them by a factor of 0.93, as recommended by Dr. Q. Ma (Columbia University).

The line list for phosphine (PH₃) has been extended up to 4763 cm^-1 to now include the tetradecad region. Line parameters from the work of Nikitin et al. (2023) have been used.

In addition, H₂-broadening and He-broadening has been extended to the tetradecad region using the functions described in Tan et al. (2022).

HITRAN2020 Intensities and Einstein-A coefficients of the bands with 4≤Δv<8 for all isotopologues of hydrochloric acid (HCl) were multiplied by a factor of 1.3 based on the measurements reported by Vasilchenko et al. (2023).

The SO line list has been updated to include the infrared vibrational transitions of the ground electronic state from Bernath et al. (2022). The PGOPHER model, provided as supplementary material to the article, was used to include additional transitions for some branches that were incomplete in the supplementary line list of Bernath et al. (2022).

MT_CKD water vapor continuum model was updated to version 4.2 with modifications to self, foreign, and self temperature dependence in IR window (590-1400 cm^-1).

Recall that in December 2022 the MT_CKD water vapor continuum model was updated to version 4.1.1, where the foreign continuum changed in far-IR.

As a reminder, the details about MT_CKD water vapor continuum model in HITRAN can be found at:

https://hitran.org/mtckd/

The air- and self-broadening parameters for C₂H₆ have been corrected for the torsional bands in the FIR. It was noticed that the broadening functions from Devi et al. (2010) were not applied correctly in the database for these bands. We thank Elizabeth Guest (UCL) for identifying this issue.

The line list for the CH₃CN molecule has been substantially extended and updated. Pure rotational, ν₈, 2ν₈, and corresponding hot bands were added to the database for the first time. The ν₄ band has been substantially updated.

The new line list is calculated based on Müller et al. (2021) and references therein.

The temperature dependences of the half-widths of CO₂ lines broadened by helium (He) have been updated using data from Deng et al. (2009) and Brimacombe & Reid (1983) .

The self-broadening parameters of the H₂ lines under the traditional .par format (Voigt profile parametrization) were updated using the corresponding parameters from the Hartmann-Tran profile parametrization reported in Wcisło et al. (2016). Specifically, γ_self, n_self and δ_self were updated using values corresponding to γ_{HT_0_self}(296), n_{HT_0_self}(296), δ_{HT_0_self}(296). Typically, it is not recommended to use Lorentzian widths determined with different profiles, however, it is still better than using the coarse approximation employed previously. The same parameters were also cloned for γ_H2, n_H2 and δ_H2.

The line list for water vapor above 4340 cm^-1 has been revised based on the evaluations carried out by Eli Mlawer and Mike Iacono (AER) using TCCON spectra from the Lamont site. The changes could be summarized into these categories:

1. Line shift parameters in HITRAN2020 that originated from Ref. ( https://doi.org/10.1016/j.jqsrt.2020.107030) were found to have errors for certain bands, resulting for instance in a large amount of positive values. While these models are being improved, the issue was fixed in the following way: The shifts that affected the quality of the residuals have been reverted back to the HITRAN2016 values or replaced with those from the AER list, which contains manual modifications of the HITRAN2016 parameters to better match the TCCON spectra.

2. The air-broadened half-widths that affected the quality of the residuals have been reverted back to the HITRAN2016 values or replaced with those from the AER list "aer3.8.1" ( https://doi.org/10.5281/zenodo.5120012), which contains manual modifications of the HITRAN2016 parameters to better match the TCCON spectra.

3. The intensities in the 4ν₂+ν₃ band were scaled down by 22%, while individual intensities (of ab initio origin) in different bands had to be scaled to match the TCCON spectra.

4. As pointed out by Alain Campargue (Grenoble), a large percentage of the lines in HITRAN2020 that were referencing W2020 MARVEL line list for the line positions were deviating slightly from the line positions in the original W2020 work. This has now been fixed.

It should be noted that the aforementioned changes affect primarily the principal isotopologue. Also, the line position changes proposed in ( https://doi.org/10.1080/00268976.2022.2051762) have not been implemented yet, but they are unlikely to impact the strong lines.

It was found that in the process of combining different line lists of ozone for HITRAN2020, the lines of the principal isotopologues of ozone in the 850-980 cm^-1 spectral region were accidentally omitted. These lines are now restored. Although most of these transitions are relatively weak, they are still important in remote sensing applications. We thank Norbert Glatthor (KIT) for pointing out this issue.

The data on this website corresponds to the HITRAN2020 edition. The updates to this edition will be announced in this section as they appear