Advanced spectral lineshapes and the HITRANonline

The new online version of the HITRAN database provides data (though limited to selected molecules/isotopes/transitions at this point) which permits modeling using spectral lineshape profiles more accurate that Voigt.   This short overview tutorial video from the HITRAN group provides a good summary of what spectral profiles the HITRAN database is currently capable of providing data for.

Hartmann-Tran lineshape profile

The usage of what is known as the Hartmann-Tran lineshape profile (partially Correlated quadratic-Speed-Dependent Hard-Collision profile, abbreviated as pCqSD-HCP) has been recommended for radiative transfer calculations to provide higher accuracy than that achievable when the Voigt profile is used.   As such the Hartmann-Tran profile is being adopted as a new standard for HITRAN simulations.   The online version of the HITRAN database (available at HITRAN.org) is gradually being modified to supply a larger number of spectral parameters needed to perform calculations using the Hartmann-Tran profile.

The algorithm behind the Hartmann-Tran profile is described in JQSRT, Vol 129, pp. 199-203 (which also contains the FORTRAN source files in Appendix A to this paper online), and the corresponding Errata.  The corresponding theoretical derivation of the Hartmann-Tran profile is presented in JQSRT, Vol 129, pp. 89-100 and the corresponding Errata.   Additionally an implementation of the Hartmann-Tran profile written in the Python language is available in the HAPI source code.

HITRANonline database records
Using the standard legacy HITRAN database format (*.par files with 160 ASCII chars per spectral record) is sufficient to run calculations using the Voigt profile but not the more accurate lineshape profiles such as the Hartmann-Tran.   As such to model the Hartmann-Tran profile one needs to use the online version of the HITRAN database which is being expanded to include additional parameters needed for such calculations.  The list below summarizes HITRANonline record format and lists individual record data fields (as per HAPI source code version introduced into the online version of the HITRAN database.   It should be noted however that the spectal data needed to perform modeling using advanced lineshapes is currently limited in HITRAN (i.e. some molecules/isotopes/transitions do not have data available for Hartmann-Tran profile simulations).

The "Identifier" column in the Table below may be used to send a request for its corresponding record parameter to be returned from HITRANonline.   Such requests are automatically generated by the HITRANonline web interface but may also be manually or programmatically constructed into HTTP-stype requests containing the Identifiers for the parameters to be returned by the HITRANonline server.  Such access technique is used in the HAPI (see HAPI source code) but may also be useful for those developing custom applications relying on HITRANonline while bypassing HITRANonline web interface or the use of HAPI functionality.   The table below was constructed from the information provided within the HAPI source code with a few changes such as using symbols $GI$, $TID$, and $*.par$ instead of the "Global isotopologue ID", the "Transission ID", and the ".par line" respectively.

Table 1:   The following identifier may be used to request data in the legacy 160-character HITRAN format.

Symbol id Identifier Units Description
$*.par$ 37 par_line - Used to request a native 160-character formatted HITRAN line from HITRANonline

Table 2:   Data fields available for each spectral line record in the online version of the HITRAN database (HITRANonline).   Note that the new data fields introduced (compared to the legacy 160-character HITRAN format) may not yet have values available for certain molecules, isotopes, and spectral line records in the HITRANonline database in which case a more simple lineshape model would have to be used in calculations (i.e. Voigt).

Symbol id Identifier Units Description
$GI$ 1 global_iso_id - Global unique isotopologue ID
$M$ 2 molec_id - Molecule number
$I$ 3 local_iso_id - Isotope number
$\nu_{ij}$ 4 nu $cm^{-1}$ Vacuum wavenumber
$S_{ij}$ 5 sw $cm^{-1} / (molecule \cdot cm^{-2})$ Line intensity
(at T = 296 K, multiplied by isotopologue abundance)
$A$ 6 a $s^{-1}$ Einstein A-coefficient
$\gamma_{air}$ 7 gamma_air $cm^{-1} / atm$ Air-broadened half width at half maximum (HWHM)
$\gamma_{self}$ 8 gamma_self $cm^{-1} / atm$ Self-broadened half width at half maximum (HWHM)
$n_{air}$ 9 n_air $cm^{-1}$ Temperature dependence exponent for $\gamma_{air}$
$\delta_{air}$ 10 delta_air $cm^{-1} / atm$ Air pressure-induced line shift
$E^{ \prime\prime}$ 11 elower $cm^{-1}$ Lower-state energy
$g^{\prime}$ 12 gp - Statistical weight of the upper state (Upper state degeneracy)
$g^{\prime\prime}$ 13 gpp - Statistical weight of the lower state (Lower state degeneracy)
$V^{ \prime}$ 14 global_upper_quanta - Upper-state "global" quanta
$V^{ \prime\prime}$ 15 global_lower_quanta - Lower-state "global" quanta
$Q^{ \prime}$ 16 local_upper_quanta - Upper-state "local" quanta
$Q^{ \prime\prime}$ 17 local_lower_quanta - Lower-state "local" quanta
$*$ 18 line-mixing_flag - Line mixing flag
$I_{err}$ 19 ierr - Uncertainty indices
$I_{ref}$ 20 iref - Reference indices
$\delta^{\prime}_{air}$ 21 deltap_air - Linear temperature dependence coefficient for air-induced pressure shift
$n_{self}$ 22 n_self - Temperature exponent for the self-broadened HWHM
$\delta_{self}$ 23 delta_self - Self-induced pressure shift, referred to p=1 atm
$\delta^{\prime}_{self}$ 24 deltap_self - Linear temperature dependence coefficient for self-induced pressure shift
$SD_{air}$ 28 SD_air - Speed-dependence parameter, air-broadened lines
$SD_{self}$ 29 SD_self - Speed-dependence parameter, self-broadened lines
$\beta_{G, air}$ 30 beta_g_air - Dicke narrowing parameter for the air broadened Galatry line profile
$y_{self}$ 31 y_self - First-order (Rosenkranz) line coupling coefficient; self-broadened environment
$y_{air}$ 32 y_air - First-order (Rosenkranz) line coupling coefficient; air-broadened environment
$qns^{\prime}$ 33 statep - Upper state quantum numbers
$qns^{\prime\prime}$ 34 statepp - Lower state quantum numbers
$\beta_{G, self}$ 35 beta_g_self - Dicke narrowing parameter for the self-broadened Galatry line profile
$TID$ 36 trans_id - Unique integer ID of a particular transition entry in the database. (The same physical transition may have different IDs if its parameters have been revised or updated)
$\gamma_{H2}$ 38 gamma_H2 - Lorentzian lineshape HWHM due to pressure broadening by H2 at 1 atm pressure
$n_{H2}$ 39 n_H2 - Temperature exponent for the H2-broadened HWHM
$\delta_{H2}$ 40 delta_H2 - Pressure shift induced by H2, referred to p=1 atm
$\delta^{\prime}_{H2}$ 41 deltap_H2 - Linear temperature dependence coefficient for H2-induced pressure shift
$\gamma_{He}$ 42 gamma_He - Lorentzian lineshape HWHM due to pressure broadening by He at 1 atm pressure
$n_{He}$ 43 n_He - Temperature exponent for the He-broadened HWHM
$\delta_{He}$ 44 delta_He - Pressure shift induced by He, referred to p=1 atm
$\gamma_{CO2}$ 45 gamma_CO2 - Lorentzian lineshape HWHM due to pressure broadening by CO2 at 1 atm pressure
$n_{CO2}$ 46 n_CO2 - Temperature exponent for the CO2-broadened HWHM
$\delta_{CO2}$ 47 delta_CO2 - Pressure shift induced by CO2, referred to p=1 atm
$\gamma^{HT}_{0{\text -}self{\text -}50}$ - gamma_HT_0_self_50 -
$n^{HT}_{self{\text -}50}$ - n_HT_self_50 -
$\gamma^{HT}_{2{\text -}self{\text -}50}$ - gamma_HT_2_self_50 -
$\delta^{HT}_{0{\text -}self{\text -}50}$ - delta_HT_0_self_50 -
$\delta^{\prime \, HT}_{self{\text -}50}$ - deltap_HT_self_50 -
$\delta^{HT}_{2{\text -}self{\text -}50}$ - delta_HT_2_self_50 -
$\gamma^{HT}_{0{\text -}self{\text -}150}$ - gamma_HT_0_self_150 -
$n^{HT}_{self{\text -}150}$ - n_HT_self_150 -
$\gamma^{HT}_{2{\text -}self{\text -}150}$ - gamma_HT_2_self_150 -
$\delta^{HT}_{0{\text -}self{\text -}150}$ - delta_HT_0_self_150 -
$\delta^{\prime \, HT}_{self{\text -}150}$ - deltap_HT_self_150 -
$\delta^{HT}_{2{\text -}self{\text -}150}$ - delta_HT_2_self_150 -
$\gamma^{HT}_{0{\text -}self{\text -}296}$ - gamma_HT_0_self_296 -
$n^{HT}_{self{\text -}296}$ - n_HT_self_296 -
$\gamma^{HT}_{2{\text -}self{\text -}296}$ - gamma_HT_2_self_296 -
$\delta^{HT}_{0{\text -}self{\text -}296}$ - delta_HT_0_self_296 -
$\delta^{\prime \, HT}_{self{\text -}296}$ - deltap_HT_self_296 -
$\delta^{HT}_{2{\text -}self{\text -}296}$ - delta_HT_2_self_296 -
$\gamma^{HT}_{0{\text -}self{\text -}700}$ - gamma_HT_0_self_700 -
$n^{HT}_{self{\text -}700}$ - n_HT_self_700 -
$\gamma^{HT}_{2{\text -}self{\text -}700}$ - gamma_HT_2_self_700 -
$\delta^{HT}_{0{\text -}self{\text -}700}$ - delta_HT_0_self_700 -
$\delta^{\prime \, HT}_{self{\text -}700}$ - deltap_HT_self_700 -
$\delta^{HT}_{2{\text -}self{\text -}700}$ - delta_HT_2_self_700 -
$\nu^{HT}_{self}$ - nu_HT_self -
$\kappa^{HT}_{self}$ - kappa_HT_self -
$\eta^{HT}_{self}$ - eta_HT_self -
$\gamma^{HT}_{0{\text -}air{\text -}50}$ - gamma_HT_0_air_50 -
$n^{HT}_{air{\text -}50}$ - n_HT_air_50 -
$\gamma^{HT}_{2{\text -}air{\text -}50}$ - gamma_HT_2_air_50 -
$\delta^{HT}_{0{\text -}air{\text -}50}$ - delta_HT_0_air_50 -
$\delta^{\prime \, HT}_{air{\text -}50}$ - deltap_HT_air_50 -
$\delta^{HT}_{2{\text -}air{\text -}50}$ - delta_HT_2_air_50 -
$\gamma^{HT}_{0{\text -}air{\text -}150}$ - gamma_HT_0_air_150 -
$n^{HT}_{air{\text -}150}$ - n_HT_air_150 -
$\gamma^{HT}_{2{\text -}air{\text -}150}$ - gamma_HT_2_air_150 -
$\delta^{HT}_{0{\text -}air{\text -}150}$ - delta_HT_0_air_150 -
$\delta^{\prime \, HT}_{air{\text -}150}$ - deltap_HT_air_150 -
$\delta^{HT}_{2{\text -}air{\text -}150}$ - delta_HT_2_air_150 -
$\gamma^{HT}_{0{\text -}air{\text -}296}$ - gamma_HT_0_air_296 -
$n^{HT}_{air{\text -}296}$ - n_HT_air_296 -
$\gamma^{HT}_{2{\text -}air{\text -}296}$ - gamma_HT_2_air_296 -
$\delta^{HT}_{0{\text -}air{\text -}296}$ - delta_HT_0_air_296 -
$\delta^{\prime \, HT}_{air{\text -}296}$ - deltap_HT_air_296 -
$\delta^{HT}_{2{\text -}air{\text -}296}$ - delta_HT_2_air_296 -
$\gamma^{HT}_{0{\text -}air{\text -}700}$ - gamma_HT_0_air_700 -
$n^{HT}_{air{\text -}700}$ - n_HT_air_700 -
$\gamma^{HT}_{2{\text -}air{\text -}700}$ - gamma_HT_2_air_700 -
$\delta^{HT}_{0{\text -}air{\text -}700}$ - delta_HT_0_air_700 -
$\delta^{\prime \, HT}_{air{\text -}700}$ - deltap_HT_air_700 -
$\delta^{HT}_{2{\text -}air{\text -}700}$ - delta_HT_2_air_700 -
$\nu^{HT}_{air}$ - nu_HT_air -
$\kappa^{HT}_{air}$ - kappa_HT_air -
$\eta^{HT}_{air}$ - eta_HT_air -
$\gamma_{H2O}$ - gamma_H2O -
$n_{H2O}$ - n_H2O -

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