Level 1B software converts the geo-located raw instrument data numbers (DN) into top of the atmosphere (TOA) calibrated radiances for all bands and into reflectances for the 20 reflected solar bands (RSB).

The L1B values reported for each band/pixel are ’scaled integers’ (SI). Keep in mind that valid SI values are in the range 0 to 32767. Values greater than 32767 are invalid “fill” values, that indicate missing pixels or data that cannot be calibrated for various reasons.

The conversion from SI to radiances and reflectances is described in the MODIS L1B Product User’s Guide, available at MCST’s web site L1B section

SI can be converted to radiance values using the band-dependent ’radiance_scales’ and radiance_offset’ values found in the hdf file. To convert the 1KM Emissive Bands Scaled Integers to radiances, convert the SI into the radiance values using
radiance = rad_scales*(SI-rad_offset).

The reflectance_scales and reflectance_offsets values are located in the L1B HDF’s Vgroup, Data Fields, and in the Dataset Attributes. These values are band dependent.