Unable to transfer mask from a product to another

Hi all,

I am working with S3 OL_1_EFR, OL_2_WFR and SL_2_WST products in snap v7. All overlapping the same area.

I would like to remove cloudy pixels from my analysis in SL_2_WST_products.

As the quality_level_cloud flag does not seem reliable over my area of interest (there is a clear cloud over-flagging near the coast when comparing to clouds in OL_1_EFR or OL_2_WFR products acquired at the same time), I wanted to compute a cloud_mask from OL_1_EFR products with the Idepix OLCI processor. Then my idea was to export the output mask values to the corresponding (same ground track) SL_2_WST products. This used to work in a previous SNAP version. Now, the idepix cloud mask gets transfered to the WST product but I am then unable to open any band from the WST product!
Before exporting the mask values, I have subsetted both OL_1_EFR and SL_2_WST products to the same area of interest and reprojected them with the same crs.

I conducted another test by trying to export some mask values from a OL_2_WFR product to a OL_1_EFR product (same ground resolution, same sensing time) and even this fails. I get the following error (which is the same message I get with Idepix, only the symbol name changes):

Failed to open image view
java.lang.IllegalArgumentException: expression: undefined symbol ‘WQSF_lsb.CLOUD’

This transfer mask technique to compute a more suitable mask for WST products used to work really well.

Do you know what I could be possibily doing wrong here? If this functionnality is broken in Snap v7, has it been fixed in v8?

If none of the above works, would you have a suggestion to compute a more reliable (and less conservative) cloud mask for SL_2_WST products? I have tried using probability_cloud_single_in==1 but this is still too conservative. I have then tried using probability_cloud_single_in==1 and sea_surface_temperature<=empirical_threshold but this is not ideal either.

I would be very grateful for your help. I would be glad provide with more inputs/details if needed!

Try the BandMerge in the Graph Builder, if you have everything collocated it should work well. BandMerge can also be applied via GPT.

Thank you for the Tip abruescas.

So I was not able to directly use Bandmerge on OL_2_WFR and SL_2_WST products (probably due to the resolution difference between both products) but I was able to use the collocation operator between both products acquired at the same time and the OL_2_WFR cloud_mask displays well on the SST band from the SL_2_WST product. I am very pleased with the results.

For future user: Note that I have subsettedto the same ROI and reprojected in the same CRS both products before collating them.