Hi Laura,
Solar_rad is broken up into the four components using the ratios
SW_FRAC_PAR = 0.45
SW_FRAC_NIR = 0.51
SW_FRAC_UVA = 0.035
SW_FRAC_UVB = 0.005
These default values can be overwritten in run_aem3d using the keys above.
If the water quality module is used then the four components are stored each timestep and can be output using the datablock keywords PAR, NIR, UVA, and UVB. If water quality is not turned on then the values are not stored.
If any short wave radiation is left when the for loop gets to the bottom then a fraction of this is reflected upwards. This fraction is defined using the sediment_reflectivity. The reflected radiation is the sum of all 4 groups and uses the extinction coefficient default_rflct_extinction