*HIT Section

RFM Driver Table Sections: HITRAN line data

03JUL24
Type
Optional Section[1], depends on whether HITRAN 'line' molecules (ID#1:99) are selected

Description
HITRAN line parameter data, in various forms

Format
Single field.
FieldTypeDescription
HITFIL C200 Name of .bin or .par File
From RFM v4.21 onwards, while the old form will continue to be supported, the recommended form is one or more records each containing a PARAMETER=VALUE structure, with optional qualifiers attached to the VALUE field. With multiple files the order of the records is significant
Parameter Value Description
BINFIL C200 Name of a HITBIN-generated binary .bin File
PARFIL C200 Name of a standard HITRAN line parameter .par File
HDBFIL C200 Name of an extracted HITRAN database .hdb File
Qualifier Type Description
(GAS(1); GAS(2); ... ) C Molecules to be included from file
(-GAS(1); GAS(2); ... ) C Molecules to be excluded from file
(WNOMIN:WNOMAX) D Wavenumber range of file [cm-1]
Type: D=Double Precision; Cn=character string, length n.

Notes
  1. The *HIT section is optional if all 'line' molecules are represented by Look-Up Tables instead, but since you are likely to have only one version of the HITRAN data then you might as well keep the *HIT section in the driver table anyway (data available in LUTs takes precedence).

    Changes from RFM v5.21 onwards (allowing for multiple files)

  2. With multiple files the RFM assumes by default (i.e., without any qualifiers) that the later files take precedence. This means, for example, that if you have alternative spectroscopic data for H2O contained in a HITRAN-format file you can list it after the 'standard' file without having to remove all H2O records for that molecule from the standard file (this is only true at a molecular level, you can't use it for specific isotopologues, eg just updating HDO records).

  3. Reading a .par file can be quite slow, so an alternative is to use HITBIN to convert it to an RFM-specific binary format .bin file. (although, having said that, I've not noticed any significant difference in time, at least not on my desktop).

  4. With .par and .hdb files the RFM first has to read through the file to determine which molecules are present in the file, and check that the file covers the required spectral range. In these cases it is quicker to use qualifiers to tell the RFM what to assume the file contains (this is not an issue with the .bin file since all the required information is in the file header and forward pointer records).

Example
Old form (up to RFM v4.20)
*HIT hitran_2012.par ! HITRAN 2012 data
New form (RFM v4.21 onwards)
*HIT PARFIL=hitran_2012.par ! HITRAN 2012 data
New form, multiple files
*HIT PARFIL=hitran_2012.par ! HITRAN 2012 data HDBFIL=hitran_2020.par(h2o;co2) ! update H2O,CO2 with new data
The same effect can be achieved with this
*HIT HDBFIL=hitran_2020.par ! HITRAN 2020 PARFIL=hitran_2012.par(-h2o;co2) ! replace everything except h2o,co2

Bugs
[none reported]