Radiometric correction for sentinel 2 images

[reza9095]

In addition to the atmospheric correction, is radiometric correction needed for sentinel 2 images?

[ABraun]

Level-1C products are top-of-atmosphere reflectance (TOA)
Level-2A products (after processing by sen2cor) are bottom-of-atmosphere reflectance(BOA)

The "dl" unit

Actually, L1C of Sentinel-2 is already reflectance data. But TOA and not BOA. However, reflectance values have no unit. See also: https://sentinel.esa.int/web/sentinel/technical-guides/sentinel-2-msi/level-1c/algorithm (section TOA Reflectance Computation) and

additionally, sen2cor makes use of a DEM to normalize slopes (more or less). Sen2cor DEM parameters