RFM File Formats

.xsc File: Molecular Cross-Section Data


Input(s), mandatory if any cross-section molecules used (unless absorption coefficients supplied from look-up tables).

Tabulated cross-section data for one or more heavy molecules (or aerosol extinction).

Specified in *XSC section of the Driver Table.

This is the HITRAN format with the addition of optional !CMNT and *** ... records.
The HITRAN format files, simply concatenated, can also be used directly.
!CMNT [optional comment record(s)]
*** IDX NXST [FMT] [WNLSET] [WNUSET] (A3,I7,I10,A10,2F10.4)
MOLEC WNOLOW WNOUPP NXSW TEM(i) PRE(i) [Start repeat for i=1:NXST]
XSC(1,i) XSC(2,i) ...
... XSC(NXSW,i) [End repeat for i=1:NXST]

Fields are read as fixed format
!CMNT A80 Comment record(s) (optional) Record starts with '!'
*** A3 Marker for start of dataset
IDX I7 Absorber Index See List of Absorbers
NXST I10 No.of (p,T) tabulations in dataset >0
FMT A10 Format (optional) ' ' or 'HITRAN2K'
WNLSET F10.4 Min.Wavenumber [cm-1] of dataset (optional) >0
WNUSET F10.4 Max.Wavenumber [cm-1] of dataset (optional) >0

From this point it is standard HITRAN format
MOLEC A20 Chemical Formula
WNOLOW F10.4 Lower Wavenumber [cm-1] for tabulation
WNOUPP F10.4 Upper Wavenumber [cm-1] for tabulation
NXSW I7 No. of Wavenumber points >0
TEM F7.2 Temperature [K] of tabulation
PRE F6.1 Pressure [Torr] of tabulation '0' treated as '760'
XSC E10.3 Absorption Cross-Section [cm2/molec]

  1. The RFM format is the same as the HITRAN format with the addition of
    (a) initial comment records.
    (b) RFM identifier record (molecule index, wavenumber range)
    While the option to have initial comment records will be maintained as these can be used to provide useful additional information eg on data source, the RFM identifier record is only supported for backward compatibility. You should now use the HITRAN files directly.
  2. The HITRAN data is now provided as single files for each (p,T) and spectral band. These have to be concatenated for use in the RFM (see Absorption Cross-sections), which expects a single file for each molecule.
  3. WNOLOW,WNOUPP: The RFM doesn't require all tabulations within a dataset to have the same wavenumber grid or resolution. Zero absorption is assumed if any (p,T) datasets have to be extended to WNLSET,WNUSET.
  4. The older data had the pressure PRE set to 0.000, which is taken to indicate atmospheric pressure 760 Torr.
  5. When used for aerosol extinction, the value in the .xsc file is multiplied by the value in the .atm aerosol profile to get the actual extinction, so there is an arbitrary normalisation factor which can be applied to either the cross-section or profile.
  6. Note that there is an older HITRAN format (prior to 2000) which is no longer supported - the easiest way to spot this is that the molecule field in the header record was 10 characters wide instead of 20. If you really do need to use data in this old format, let me know.

Spectrally flat aerosol spectrum over MIPAS range.
***     50         1                                                            
  AEROSOL   685.0000 2410.0000         2     293.0    0.0000  
 1.0000    1.0000


Bug#23 (Fixed RFM v5.10)
Bug#16 (Fixed RFM v5.02)