Sentinel-2 Level1B and Level1C


I am wondering where I should start post this question about Sentinel-2 Level1B and Level1C products .
Both level are TOA , Do you think if we pre -process Level-1B we will get Level-1C that has alreay Atmospheric correction, cloud masking, and orthorectification corrected for users ?
and what the point from having two products for TOA?

Thanks for your help!

Dear Daniel1,

Please be informed that:

  • Level-1B product provides radiometrically corrected imagery in Top-Of-Atmosphere (TOA) radiance values and in sensor geometry, each Level-1B product is composed of an ensemble of granules that are 25 km across track (AC) by 23 km along track (AL). Additionally, this product includes the refined geometrical which is used to generate the Level-1C product. Level-1B pixel coordinates refer to the centre of each pixel.

  • Level-1C product is composed of 100 km² tiles (ortho-images in UTM/WGS84 projection). The Level-1C product results from using a Digital Elevation Model (DEM) to project the image in cartographic coordinates. Per-pixel radiometric measurements are provided in Top Of Atmosphere (TOA) reflectances with all parameters to transform them into radiances. Level-1C products are resampled with a constant Ground Sampling Distance (GSD) of 10, 20 and 60 m depending on the native resolution of the different spectral bands. In Level-1C products, pixel coordinates refer to the upper left corner of the pixel.

  • Level-2A product provides Bottom Of Atmosphere (BOA) reflectance images derived from the associated Level-1C products. Therefore, each Level-2A product is also composed of 100 km² tiles in cartographic geometry (UTM/WGS84 projection). Level-2A products generation can be performed by the user through the Sen2Cor using as input the associated Level-1C product.

For further details please consult the Sentinel-2 User Handbook available at

1 Like

Thanks Fabrizio for your reply.
I just wondering if you know if there is a tutorial on the pre-processing Level-2A product?

Thanks again for your help and time!

Dear Daniel1,

Could you please clarify what do you mean for pre-processing Level-2A products?

In fact, that Sen2Cor (Sentinel-2 atmospheric correction processor) takes as input S2 L1C data (ortho-rectified TOA reflectance), therefore you will not need to pre-process the data downloaded from SciHub (


1 Like

Thanks again Fabrizio. Your time and help much appreciated!
I want to use S2 images for crops detecting and I was wondering what pre-proccess required for S2 images before using them in Crops classification.