RFM Flags: Include line-coupling in spectral calculations
21MAR24
Enabled
Include line-mixing, also known as line-coupling,
for any CO2 lines for which (internal)
pretabulated data exists.
Use the 1st order line coupling coefficients extracted for any molecule using
spectroscopic data in the HITRAN Database format.
Disabled
Ignore line mixing
Restrictions
None.
Notes
Line-mixing (or line-coupling)
is primarily a correction affecting spectral regions where
line-intensities, and densities, are greatest. However, it does add
significantly to the computational cost. The general recommendation is to
try running the RFM with/without the
MIX flag for the required calculations
and see if it makes sufficient difference to justify its inclusion.
The standard HITRAN 160-character .par file format does not include
line-mixing coefficients, so the only option with this spectroscopic data is
to use the RFM's internal line mixing coefficients stored for CO2 lines,
which uses a first order model from Tobin & Strow (1994),
See subroutine ymix_fnc.f90 for details.
The HITRAN Database format,
introduced with RFM v5.21,
allows for
line mixing parameters for any molecule (although in practice most entries
in the HITRAN database are blank).
