Quote:I ran the MODO-4 in solar irradiance mode to derive downward flux to the surface. But when I change the surface reflectance (this is the only changed parameter) within the “sepc_alb.dat” , I got the totally same results. I tested the same tp5 files in original MODTRAN (command line no GUI) and it brought different results with 3 different surface reflectance. Then I changed the install position of MODO software but no use. I want to know what’s wrong here.
Calculating the total solar Flux in MODO/Modtran requires using the radiance mode and not the irradiance mode. In radiance mode, you need to select 'Write TP8 Flux' (modo 4) in card 1a
and further, you shuld select the 'Flux' flag in card 4. This will write a solar flux *flx file, which contains the adjacency irradiance in addition to the direct irradiance - irradiance mode only calculates the direct irradianc and is not affected by the adjacent reflectance joice.