Sentinel 2 assets available in Google Earth Engine

Dear Simon,
this is awesome!!!
I’m really looking forward to use S2 L2A data in GEE! Finally!

Do you already know when the data are accessible for the public?

All the best

Florian

The ingested assets are already available in EE, we just have not yet added a catalog entry or ingested everything that we downloaded. It’ll take a few weeks to catch up. A copy on Cloud Storage is also available, it’s just not documented yet.

S2 SR is now in the EE catalog: https://developers.google.com/earth-engine/datasets/catalog/COPERNICUS_S2_SR

I found a little mistake in the GEE documentation. Where the bands are described it is said that the value range is 1 to 11 for the SCL band. But actually it is 0 to 11. 0 is no-data.


https://sentinel.esa.int/web/sentinel/technical-guides/sentinel-2-msi/level-2a/algorithm

Marco - this is actually intentional. I used the value of 0 as the fill value to mask out such pixels in the SCL band. Do you think this would cause issues?

Probably not directly issues, but maybe confusion. As it caused for me.
So you have masked these pixels already. But I’m not sure if I understand this correctly. What does it mean in this case you have masked them out? What happens if one wants to get the value for such a pixel? Which value will he get? Or is it not possible to access such pixels?

I can add a note in the docs that 0 is masked out.

Each EE pixel retrieval operation returns a tuple (pixel_value, mask_value). If the pixel is fully present, mask=1. If the pixel is fully masked out, mask=0. If the pixel is partially masked out (which happens in pyramided layers that combine fully present and fully masked-out pixels at lower levels), 0 < mask < 1.

1 Like

Okay, now I understand. Makes sense.
But a note might be helpful.

cool!
It is possible to learn which version of the Sen2Cor processor has been used to generate the 2A level data?

I see that metadata state that the processing baseline is 02.11
Does it mean that Sen2Cor 2.11 has been used? The newest stand alone version is 2.55…

We just download the assets generated by ESA. I think we put all the relevant metadata onto the assets, but if not, let me know.

No one knows with which version of sen2cor the data has been processed. It is almost impossible to figure it out from the metadata shipped with the L2A products.
The latest internal sen2cor version is 2.8, as far as I know. The release of it was planned one month ago. But obviously, there is a delay for some reason.

You might want to adjust the “Dataset availability” (https://developers.google.com/earth-engine/datasets/catalog/COPERNICUS_S2_SR) as L2A data from ESA are only available since mid March 2017 (Europe) and mid December 2018 (global).
Or do you plan to reprocess old data as well?

2 Likes

Thank you Marco,
I know it is supper difficult to get this information from ESA but I remember last year i eventually managed to find this piece of information on the ESA website. At that time, the processor used for L2A data was very outdated and I ended up processing L1C to L2A myself. I am not sure whether ESA recalculated the archives since.
I find it interesting though that the internal sen2cor version is 2.8 whereas the one featured on the website now is 2.5.5 [http://step.esa.int/main/third-party-plugins-2/sen2cor/].
lets stay tuned

Grega: I was optimistic and set the start date to be the same as S2 L1 start date in the hope that eventually L1 for older assets will be generated as well. But if this is not going to happen in the next few months, yes, I will need to adjust the start date.

This will certainly not happen in the next few months as there is currently no plan set to do it at all. There are just a lot of wishes :slight_smile: Based on past experience this means that in 2019 there will almost certainly not be anything else.

Do you happen to know what the blocking factor(s) are? I will be at LPS in May and would like to discuss this.