*XSC Section

RFM Driver Table Sections: Absorption Cross-Section Files

11MAR25
Type
Optional Section — depends on whether any 'cross-section' molecules are selected.

Description
Specify molecular absorption cross-section files.

Format
Multiple fields, any order
FieldTypeDescription
FILXSC C200 Name of .xsc File
DEFXSC C200 Default .xsc Filename template (contains '*' character)

Notes
  1. 'Cross-section' molecules are those whose absorption coefficient k is tabulated as a function of wavenumber, pressure and temperature rather than calculated from individual line parameters. These are usually the heavier and more complex molecules not included in the HITRAN 'line' database.

  2. The RFM assigns indices ≥100 to the most common of these, but any arbitrary molecule can be used.

  3. FILXSC can represent files in the original HITRAN .xsc format, as well the RFM .xsc format (which is the HITRAN format with extra header records inserted). However you will first need to concatenate the original HITRAN files into a single file, eg if you've downloaded a set of files N2O5*xsc from the HITRAN web-site, then
    cat N2O5*.xsc > n2o5.xsc

  4. If a filename template DEFXSC is supplied, identified by containing a '*' character, first all the explicitly specified files are read, then '*' character in the template is expanded to the lower-case absorber name of any remaining molecules (using the 'fnn' form for CFCs).

  5. Cross-section data is provided as absorption coefficient spectra measured at a set of arbitrary (p,T) coordinates. For particular path (p,T) conditions, the RFM interpolates using triangulation or, for points outside the triangulation domain, interpolation to the value at the closest boundary point.

Example
*XSC f11.xsc ! Cross section data for CFC-11 f12.xsc ! Cross section data for CFC-12 ./rfm_files/*.xsc ! Other data, eg './rfm_files/f22.xsc'

Bugs
[none recent]