Cloud or Oceanic front? Problems with sea surface temperature cloud mask - Sentinel 3

Hi community!

Looking at the cloud masks of S3, we notice that it looks more like an oceanic front, than a cloud.

I could do some custom processing to reduce this effect, but that would require changing the cloud mask parameters and using the level 1 files, then doing the processing at higher levels.
However, I am working with a time series, therefore, a custom processing is not an option.
Does anyone have the same problem?

Thank you!!

Can you tell on which exact product you see this?

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Sentinel 3 SLSTR - Sea Surface Temperature - Level 2

In the left image you see the sea surface temperature and in the right image you see the cloud mask (l2p_flags_cloud mask) from this product.

Acquisition Period: 01-03-2021
Product Type: SL_2_WST_

Thanks. Could you even be a bit more precise. There are 27 products available for the 1st of March.
The name of file would be helpful or the acquisition time.
Yuo have downloaded it from Eumetsat CODA?

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I downloaded via CODA.
Here is the name: S3A_SL_2_WST____20210301T203618_20210301T221718_20210303T080314_6059_069_085______MAR_O_NT_003.SEN3

And the area is in the Adriatic Sea (north)

I would agree it looks more like a ocean front.
In my screenshot the upper image shows the quality_level band. But this gives also no indication how to work around.

Maybe someone here in the forum has an idea or you ask Eumetsat directly.
This is probably a good idea as they might be interested in this issue too. And maybe they already know how to solve it.
You can either us this form: Contact us | EUMETSAT
or send an email to

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Hi Marco, thank you for taking the time to help me! I really appreciate it.
I will contact EUMESAT, additionally this is not the only image with this “problem”.
Let’s see what they say, and then I can post here their answer.

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