Understanding the Sentinel 3 cloud mask band

s3tbx
#1

Hi,

I have opened the “cloud_in” band from a Sentinel 3 acquisition in Snap. Each pixel in the mask seems to be from a small set of integer values, leading me to believe that the mask needs to be decoded in order to extract quantitative information about the cloud probability for that pixel. However I have not been able to find a resource online that explains how to perform the decoding of the mask values.

Could someone point me toward a document explaining what the values of the cloud mask represent please?

Ultimately I would like to import or generate a cloud probability mask in python. So a document containing explicit instructions of transforming the “cloud_in” pixel value to the probability that a cloud is present at that pixel would be desirable.

Many thanks,
David

#2

Subsequent to this post, I found this discussion: https://forum.step.esa.int/t/cloud-mask-for-slstr-lavel1b-image/8458/3

I still have not found a resource for explicitly spelling out how to extract the probability of cloud cover for a given pixel but the above link was helpful for getting me closer to that goal.

#3

Hi David,

There is some information about the cloud masks including Bayesian cloud mask probabilities for SLSTR in the handbook here: https://www.eumetsat.int/website/wcm/idc/idcplg?IdcService=GET_FILE&dDocName=PDF_DMT_921927&RevisionSelectionMethod=LatestReleased&Rendition=Web

If you need more detail - you can also drop me a query via ops@eumetsat.int and I can help further.

Hayley