RFM Driver Table Sections

*SPC Section: Spectral Range & Resolution

04AUG17

Type
Primary Section#3

Description:
Define range(s) and resolution(s) of output spectra generated by RFM.
Units are [cm-1] by default, or [GHz] if the GHZ flag is enabled.

Format
Multiple records, order may be significant.
There are four types of record whose structure is determined by the number of fields (1-4) contained in the record (the 3 or 4-field records are probably what you want)
  1. FILSPC
  2. LABSPC RESSPC RFM v4.35 onwards: LABSPC FILSPC
  3. LOWSPC UPPSPC RESSPC
  4. LABSPC LOWSPC UPPSPC RESSPC
Field Type Description Range
FILSPC C*200 Name of a .spc file
RFM v4.35 onwards: Spectral file or .grd file
LABSPC C*8 Label for spectral range
RESSPC R*8 Resolution [cm-1] of output spectra 0.0004 (=1/MAXFIN):1.0 >0:1 for RFM v5
I N.Pts/[cm-1] of output spectra 1:2500 (=MAXFIN) >1 for RFM v5
LOWSPC R*8 Lower wavenumber [cm-1] for output spectra 0.001 - UPPSPC
UPPSPC R*8 Upper wavenumber [cm-1] for output spectra LOWSPC - 20000

Notes
  1. The RFM calculates each spectral range sequentially in the order in which they appear in this section, but the results do not depend on the order. There are no benefits other than convenience in specifying more than one spectral range within a particular driver table.
  2. FILSPC: a single field in the record is interpreted as the name of a .spc file containing predefined spectral ranges and resolutions.
    RFM v4.35 onwards: this can be either an RFM output Spectral file or .grd file defining the range and regular/irregular grid for the output.
  3. The LABSPC spectral range labels can contain up to 8 characters (no internal spaces). These are case-sensitive and appear as part of the output filenames, so labels are compulsory if more than one spectral range is required (so that the different output files are distinguished).
  4. It is possible to have different LABSPC labels identifying the same upper and lower limits provided the resolution is different. ( RFM v4.35 onwards: same resolution allowed)
  5. Predefined LABSPC labels may be redefined (with a warning in the rfm.runlog file), but once the resolution has been set the label may not be further redefined. (RFM v4.35 onwards: predefined labels not supported)
  6. RESSPC values < 1 are interpreted as resolution in [cm-1] while values > 1 (integers) are interpreted as 'number of points per wavenumber' (ie reciprocal of the resolution). If the GHZ Flag is selected, the value is always interpreted as GHz.
  7. Setting RESSPC = 0 is the method for predefining a range without actually initiating a calculation. This would normally only be done in a .spc file. To activate it, the LABSPC is quoted again, but with a non-zero resolution (using a 2-field record) (RFM v4.35 onwards: RESSPC=0 not supported)
  8. The RESSPC resolution applies to the output spectra - if an ILS convolution is required the RFM by default performs internal calculation at 0.0005 cm-1 resolution (use the FIN Flag to alter this) or the closest sub-multiple of the output spacing.
  9. A warning message is printed in the rfm.runlog file if spectral lines at the highest required tangent level are unlikely to be unresolved at the resolution selected for the fine-mesh calculation (ie RESSPC in the absence of any ILS convolution).
  10. The maximum resolution RESSPC is determined by the value of MAXFIN parameter in rfmsiz.inc (RFM v5 has no such limit)
  11. The limiting values for LOWSPC and UPPSPC are set in spcchk.for (spcchk_sub.f90 in RFM v5) and are basically just sanity checks (although a value 0cm-1 causes problems).
  12. If the GHZ Flag is enabled the requested spectral range and resolution are converted to wavenumber internally using the VLIGHT value in phycon.inc (phycon_dat.f90 for RFM v5) (30GHz approx 1cm-1) and the calculation proceeds in the same way.
  13. RFM v4.35 onwards: irregular output grids can be specified (although not for spectrally convolved outputs - ILS or AVG flags) using FILSPC as either a .grd file or a precalculated RFM output spectral file already on the irregular grid.

Examples
This is a single, user-specified, unlabelled spectral range
*SPC   
    1020 1030 0.01     ! 1020-1030 cm-1 @ 0.01 cm-1 resolution
This is a pair of labelled spectral ranges @ 40pts/wno.
*SPC
    BandA  685  970 0.025     ! Band A
    BandB 1215 1500 0.025  ! Band B
The next example uses files to specify range/resolution (RFM v4.35 onwards)
*SPC   
    A  rad_10000.asc        ! Clone range/res from previous RFM output
    B  bspc.grd                   ! Irregular grid output
See Example in Spectral Files for structure of bspc.grd.

Bugs
Bug#126 (Fixed v4.36)
Bug#125 (Fixed v4.36)
Bug#97 (Fixed v4.33)
Bug#51 (Fixed v4.25)
Bug#47 (Fixed v4.23)