Best practice in acquiring and atmospherically correcting Sentinel-2 data

Greetings,
I am interested to hear suggestions from the community on what is currently the best way to acquire and atmospherically correct Sentinel-2 data. I have previously worked mostly with Sentinel-1 data and only sporadically with Sentinel-2 data so I really would appreciate some input on how to go about this efficiently. I have checked other discussions on this forum as well as on stack overflow, but haven’t found the answers I am looking for. If you believe that my questions are already answered elsewhere, please let me know!

I am looking to do analysis for which I would need atmospherically corrected data. As far as I can tell, this is not available prior to December 2018, however I would really want to go back further than that. For my study site, Level 1C data seems to be “offline” for older imagery when checking the Copernicus Open Access Hub. Other websites (e.g. USGS) seem to provide the data but only in “.tif” format, and if I understand correctly I need it in the “.SAFE” format to use sen2cor? I have now downloaded the data in “.SAFE” format using the Google Cloud API (https://cloud.google.com/storage/docs/public-datasets/sentinel-2). This mostly worked well as far as I can tell, but some files seem to be corrupted. When trying to apply sen2cor in SNAP to some of these images, it finishes in 2 seconds (unrealistically fast) and gives the error “WindowsError: [Error 3] The system cannot find the path specified:” followed by different paths depending on which image I try to process. However, I can open the “.SAFE” files in SNAP and look at the different bands.

I am also looking for advice on how to go about using sen2cor. I have installed the plugin for SNAP which seems to work (for images that were correctly downloaded). However, as far as I can tell it is not implemented for batch processing? Would everybody’s recommendation be to use sen2cor via the command line tool? And could you point me towards an example where somebody did this successfully?

Generally what is everybodys preferred way of acquiring and atmospherically correcting Sentinel-2 data which is not available via the Copernicus Open Access Hub? Input would be really helpful and greatly appreciated.

Thank you very much in advance for you time and your input!
Helena

Actually, “offline” products can still be purchased from the official hub: ESA Copernicus data access - Long Term Archive and its drawbacks

But there are also other portals which allow the download of all products in batch mode, for example PEPS.

Please have a look at this list of sources: https://krstn.eu/awesome-Sentinel/
It also provides different methods for atmospheric correction.

Maybe the products from the Google storage are slightly different from the officially provided ones? You could try to download one of the products which failed in sen2cor from another source and compare if the problem persists.

About batch processing of sen2cor: