Location of file holding the extraterrestrial spectrum.  

solar_file filename [unit]

 
The file must contain two columns. Column 1 is the wavelength in nm, and column 2 the corresponding extraterrestrial flux. The user may freely use any units he/she wants for the extraterrestrial flux. The wavelength specified grid defines the wavelength resolution at which results are returned. However, the wavelength range is determined by wavelength. solar_file may be omitted for thermal radiation calculations (source thermal) as well as transmittance and reflectivity calculations. If omitted, the output resolution equals the internal wavelength grid which the model chooses for the radiative transfer calculation. Comments start with #. Empty lines are ignored.

For some purpuses it is useful to tell libRadtran the units of the spectrum. This can be done with the optional second argument. If unit is set to per_nm libRadtran assumes that the unit of the spectrum is W/(m2 nm), if set to per_cm-1 it assumes W/(m2 cm-1). Note that solar_file is ignored if correlated_k is specified.