On which stage of their creation do Sentinel-2A products undergo atmospheric correction?

s2tbx
#1

As part of my thesis I need to reference the way in which the images I used were atmospherically corrected, but since I worked using L2A products, I never needed to apply atmospheric correction myself.

I am aware that L1C products can be corrected using Sen2Cor, among other methods, but I can’t seem to find about how and when L2A products undergo atmospheric correction ? Does the Sentinel-2 system itself apply such a correction when creating the image ? Is it done as the image is saved in the database ? The atmospheric correction method used is the same as Sen2Cor’s ?

Thank you in advance !

#2

I have a similar doubt. I am analyzing some 2017-2018 images. If I take 1C and 2A images from same date and process the second one with sen2cor i have different values.
So, what is the treatment that use in scihub?

#3

the differences have already widely been discussed, e.g. here: Sentinel-2 L2A from Sen2Cor does not match values of downloaded S2 L2A - #5 by ABraun

#4

Can you give me an opinion?

I am working with 2017-2018 images using sen2cor 2.5.5. Some are older than this plugin and are in 2Ap level.

I read yours links, and I discovered that i can assume little diferrences. But these olders images show big differences.

This are a November-2017 image´s values.(L2Ap older than sen2core 255)

November
November1920×577 29.5 KB

And this are a May-2018 image´s values.(L2A newest tan sen2core 255)
May
May1882×539 25.4 KB

I need to process some Sentinel 2B images that not have a L2A version on scihub and I want use it toghether.

L2Ap images have problems, the proble are sen2cor 255 or I had made some mistakes?
You recommend to me reprocess these images?

Thanks.

#5

I found your opinion on this thread Sen2cor: Level-2A meteadata error,
I’m starting to think the problem is L2Ap

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