rpv_file fileBidirectional reflectance distribution functions for a variety of surfaces are given in the paper. This option is only supported with solver disort2 and rte_solver montecarlo (MYSTIC). The columns of the input file are wavelength [nm], rho0, k, and theta. The parameters are interpolated linearly to the internal wavelength grid. To make sure that the results are reasonable, specify the RPV data on a wavelength grid similar or equal to that used internally for the radiative transfer calculation! Optionally, a fifth column with a constant scaling factor may be defined which, however, is only used by rte_solver disort2.