*LEN Section | ![]() | ![]() |
RFM Driver Table Sections: Ray Path | 03JUN24 |
Field | Type | Description | Units | Range | |
---|---|---|---|---|---|
| C200 | Name of a .dat file [1] | |||
| R | Path length | km | >0
| |
UNITS= | C2 | Units for path length[2] | ∈ {'km', 'm', 'cm', 'mm'} |
χ = k ρ swhere ρ is the absorber density and s is the path length. The aim is to set ρs =1 mole/m2, so that, numerically, χ=k.
Expanding ρ= vp/(RT), at temperature T=296 K and standard atmospheric pressure p, assuming a volume mixing ratio of v=1 ppmv (keep the concentration low to return air-broadened k rather than self-broadened)
s = (1 mole m-2 ) ( R T )/( v p )
= (1 mole m-2 ) ( 8.3145 J mole-1 K-1 × 296 K) / ( 10-6 × 1013.25 Pa )
= 2.4289 × 106 m = 2428.9 km
*LEN UNITS=cm 50.3 ! Output filenames will be, eg tra_50300.asc