RFM Output Files

Contents
24AUG23

Introduction

Running the RFM will always create a file rfm.log (plus any run_ID extension to the filename). This contains diagnostic information on the progress of the particular run of the RFM, eg listing section of the Driver Table being read, names of files which are about to be opened, warning messages.

Other output files depend on the Driver Table, specifically on the Flags enabled in the *FLG section of the driver table.

Spectral Files

The main purpose of the RFM is to generate spectral files, written either as plain text (ASCII) or Binary (BIN flag) files, in Single or Double (DBL flag) precision, on regular or irregular spectral grids, and specified in wavenumbers [cm-1] or GigaHertz [GHz] (GHZ flag).

A separate file is generated for each spectral range, label [s] (as defined in the *SPC section) and viewing geometry (altitude/angle/secant) [t] (as defined in the *TAN section).

The type of spectrum, e.g. absorption, radiance, is also selected by various three letter flags in the *FLG section of the Driver Table, as listed below.

Flag Description Units Default Filename
ABS Absorption (=1-transmission) Spectrum [none] abs_[s][t].asc
BBT Brightness Temperature Spectrum K bbt_[s][t].asc
COO Cooling Rate Spectrum (with FLX Flag) K/day/cm-1 coo_[s][t].asc
OPT Optical Depth (=-ln(absorption)) Spectrum [none] opt_[s][t].asc
RAD Radiance Spectrum, or nW/(cm2 sr cm-1) rad_[s][t].asc
(+ FLX flag) Radiance Flux Spectrum W/(m2 cm-1)
RJT Rayleigh-Jeans Temperature Spectrum K rjt_[s][t].asc
TRA Transmission Spectrum [none] tra_[s][t].asc

Diagnostic Files

Additional diagnostic information (ASCII files only) can be produced for the internal profile, ray-tracing and line-by-line calculations, with separate files generated for different line-of-sight angles [l] (as specified in the *ATM section if GRA flag selected), tangent height/viewing geometry [t] (as specified in the *TAN section) and spectral range [s] as specified in the *SPC section) respectively.
Flag Description Filename
PRF Atmospheric Profile prf_[l].asc
PTH Ray Path Diagnostics pth_[t].asc
WID Widemesh Diagnostics wid_[s].asc

Look-Up Tables

Instead of spectra, the RFM can also generate look-up tables of absorption coefficient tabulated as functions of pressure, temperature and wavenumber. One table is generated for each spectral range [s] (as defined in the *SPC section) and absorbing species [g] (defined in the *GAS section). These can be used as input files (LUT flag) as a faster alternative to line-by-line calculations [see RFM LUTs]
Flag Description Units Filename
TAB Absorption Coefficient table [m2/kmol] tab_[s][g].asc

Changing Output Filenames

The RFM has default filename templates for each type of output file, as listed in the tables above, which will create the files in the user's directory. The actual filenames as they are opened are listed in the rfm.log file.

These filename templates, including redirecting to different directories, can be changed using *OUT section of the Driver Table.

Another way to modify the output filename (eg to distinguish the output from similar runs) is to enter characters in response to the Run_ID prompt.

Other Output Options

Flag Description Effect
BIN Write spectra and LUTs as Binary files rather than ASCII files Generates smaller files and faster I/O, but less straightforward to read
DBL Write spectra as double precision Internal radiance/transmittance are stored as double precision but output by default is single precision. This option generates larger output files.
GHZ Write spectra with GigaHertz spectral grid (default is cm-1) The spectral axis of the output files is changed to GHz instead of wavenumbers. The spectral range/resolution (*SPC section of the driver table are also interpreted as GHz rather than cm-1
NEW Open output files with STATUS='NEW' in FORTRAN OPEN statement rather than STATUS='UNKNOWN' Avoids overwriting any existing files of the same name (any attempt will result in a fatal error condition)