*SPC Section

RFM Driver Table Sections: Spectral Range/Resolution

17MAR25
Type
Primary Section#3

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

Format
Multiple records, arbitrary order
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)
Record Structure
Either: FILSPC
Or: LABSPC FILSPC
Or: LOWSPC UPPSPC RESSPC
Or: LABSPC LOWSPC UPPSPC RESSPC

Fields
Field Type Description Units Range
FILSPC C200 Name of a .spc file or .grd file. [2] [6]
LABSPC C8 Label for spectral range [3]
RESSPC D Resolution of output spectra [4] [5] cm-1 or GHz[8] 0< : ≤1
Or: I N.Pts/(cm-1) of output spectra 1 ≤ :
LOWSPC D Lower wavenumber for output spectra cm-1 or GHz[8] 0.001[7] ≤ : < UPPSPC
UPPSPC D Upper wavenumber for output spectra cm-1 or GHz[8] LOWSPC < : ≤ 50000[7]
Type: I=Integer; R=Real; D=Double Precision; Cn=character string, length n.

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 (the same list of absorbers would be applied for all spectral ranges).

  2. FILSPC: a single field in the record is interpreted as the name of either an existing an RFM output Spectral file or an irregular .grd file, whose range and resolution (or irregular grid) will be copied.

  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. Labels are compulsory if more than one spectral range is required (so that the different output files are distinguished).

  4. RESSPC values <1 are interpreted as resolution in cm-1 while values >1 (integers) are interpreted as 'number of points per wavenumber' (i.e. reciprocal of the resolution). If the GHZ Flag is selected, the value is always interpreted as GHz.

  5. The RESSPC resolution applies to the output spectra — if spectral convolution is required (ILS or AVG Flag) the RFM by default performs internal calculation at 0.0005 cm-1 resolution (set by DEFFIN in rfmcon_dat.f90 — use the FIN Flag to alter this) or the closest sub-multiple of the output spacing.

  6. For irregularly-spaced output spectra (only possible with unconvolved spectra) the output range/spacing is specified by FILSPC

  7. The limiting values 0.001 – 50000 for the spectral range are set in spcchk_sub.f90 and are basically just sanity checks (although a value 0cm-1 causes problems).

  8. If the GHZ Flag is enabled the requested spectral range and resolution are converted to wavenumber internally using the VLIGHT value in phycon_dat.f90 (30GHz ≈ 1cm-1) and the calculation proceeds in the same way.

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/(cm-1) (40 instead of 0.025 produces the same result)
*SPC BandA 685 970 0.025 ! Band A BandB 1215 1500 0.025 ! Band B
This example uses files to specify range/resolution
*SPC A rad_10000.asc ! Clone range/res from previous RFM output B bspc.grd ! Irregular grid output

Bugs
[none recent]