Revising the line-shape parameters for air- and self-broadened CO2 lines toward a sub-percent accuracy level

The update of the line positions and intensities in the line list of carbon dioxide for the HITRAN2020 spectroscopic database

“…We hope that new experimental data will become available for further validation tests of bands [36,37] and the different CO2 databases [12,17,23] for the 11102-00001 bands of the 12 C 16 O2, 13 C 16 O2, and 16 O 12 C 18 O isotopologues with centers: 1933 cm -1 , 1897 cm -1 , and 1903 cm -1 , respectively. The TCCON observations considered here cover the 3950 to 9500 cm -1 spectral region.…”

“…This substitution resulted in some cases where transitions in a given band would have intensities from both ab initio calculations as well as those from CDSD. Although this approach was justified in many cases, a number of inconsistencies in the rotational distribution of intensities in HITRAN2016 were revealed in CRDS spectra of 18 O and 13 C enriched and natural CO2 near 1.74 µm [39,40,46]. In isotopologues, we present in Table 1 the set of bands that were checked and affected by this issue along with the alternative intensity sources for these bands used in HITRAN2020.…”

“…A major update of the line-shape parameters of CO2 broadened by air and CO2 is described in Ref. [13]; this involved both enhancing the HITRAN database and improving completeness. A systematic extrapolation method was introduced for producing the air-and self-half width (broadening) Voigt profile parameters for unmeasured transitions [61], based on the measurements reported in Ref.…”

“…Since the release of the HITRAN2016 database [12] ,many new experimental and theoretical data have become available, and they can be used as sources for improving line positions, line intensities, and line-shape parameters of CO2. The HITRAN-related updates, including the CO2-air and CO2-CO2 line-shape parameters together with the speed dependence of the broadening parameters, their temperature-dependent exponents, the full and first-order line mixing as well as their temperature dependencies have been published in Hashemi et al [13].…”

“…The revision which updates the air-and self-broadened line-shape parameters of CO2, described in Ref. [13], will be discussed in Section 7. The presentation of the final version of the HITRAN2020 CO2 line list will be given in Section 8, followed by closing discussion and conclusions in Section 9.…”