Solar radiation enters the Earth's atmosphere with a portion being scattered by clouds and aerosols.

Processing, archiving and distributing Earth science data
at the NASA Langley Research Center

What is the difference between Level 1A, Level 1B1, and Level 1B2?

Level 1A data (the Reformatted Annotated Product, file names containing "FM_SCI") contain raw digital counts from the MISR camera charge-coupled device (CCD) focal planes. At Level 1B1 (the Radiometric Product, file names containing "RP"), the values correspond to calibrated radiances. At Level 1B2 (the Georectified Radiance Product, file names containing "GRP_ELLIPSOID" or "GRP_TERRAIN") the radiance data are geolocated, and geometric co-registration of the data from the different bands and camera angles is performed by resampling to a Space Oblique Mercator (SOM) grid. L1A and L1B1 use the HDF-EOS "swath" interface, and L1B2 uses the HDF-EOS "grid" interface. Most users do not need the L1A and L1B1 data.