the sentinel-2 level 2A is a BOA reflectance pre-processed product, so it was corrected for the atmospheric disturbance.
Are the level 2A products topographically corrected?
If yes, are the correction, both atmospheric and topographic, reliable? Which kind of correction they use?
Thank you very much!
There's no better place to go than the ESA Sentinel-2 User Handbook:
https://sentinel.esa.int/documents/247904/685211/Sentinel-2_User_Handbook
Among other things, it contains all the references to papers describing the atmospheric correction algorithms.
Sentinel 2 level 2 products distributed now by ESA/Copernicus are atmospherically corrected by SEN2COR package (as can be also done by the user, because the program is free software), it is therefore also good to look into the SEN2COR Configuration and User Manual at
http://step.esa.int/thirdparties/sen2cor/2.4.0/Sen2Cor_240_Documenation_PDF/S2-PDGS-MPC-L2A-SUM-V2.4.0.pdf
and possibly other documentation at
http://step.esa.int/main/third-party-plugins-2/sen2cor/
From the manual:
"Sen2Cor is a prototype processor for Sentinel-2 Level 2A product formatting and
processing. The processor performs the tasks of atmospheric-, terrain and cirrus
correction and a SC of Level 1C input data. Level 2A outputs are: Bottom-Of-
Atmosphere (BOA), optionally terrain- and cirrus corrected reflectance images,
AOT-, WV-, SC maps and Quality Indicators, including cloud and snow
probabilities."
So the Level-2A is "terrain corrected", which I suppose means topographic correction as well, but this correction is optional - look into the matadata of the product used to see if it had been used (I do not have the product at hand now, but I suppose it should be apparent in the product metadata).
As to the quality or reliability of the correction, it depends on what is the intended use and it is something which is still being evaluated by the community - there are articles you can find on the subject. Aso be aware, that the SEN2COR package is still under development, with quite frequent updates, so it is getting better with time and some problems described in older publications may be solved by now.
Last remark, the SEN2COR corrected level-2 product is not the only possibility. Besides several methods of doing the atmospheric correction yourself in various other software packages, there is for example the project Harmonized Landsat Sentinel (HLS) by NASA at
https://hls.gsfc.nasa.gov/
providing for download selected Landsat and Sentinel-2 data corrected by method allowing to concurrently use both products in one analysis (or it is the aim of the project). The correction method used includes BRDF adjustment, which may make it more precise for time-series analysis.
Tomáš Brunclík,
I am using sentinel-2 level 1C product for image classification. What type of correction do I need to do ? where can I learn them? Thank you in advance.
It depends, but I think it is off-topic here. As a starter maybe look at this topic
https://www.researchgate.net/post/Do_I_need_to_do_Atmospheric_Correction_for_the_Landsat_images_to_do_land_use_classification_How_can_the_TOA_could_help
if my or other's answers there are helpful (Landsat and Sentinel imagery classification is based on the same techniques), then try to search forums here and/or review articles for Sentinel-2 classification plus keywords specific to your problem and if you still need, ask your question as a new topic.
what is the best for lithological discrimination level 1c or level 2A?
Haijun Li , I think it is not BRDF corrected, but I was not following developments of the algorithm for some time, so I can be mistaken.
- Badges
- Science topic
- Similar topics
- Correction