L2gen Sentinel-3 clouds and gaps

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jvaldezch
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Joined: Fri Aug 24, 2018 2:52 pm America/New_York

L2gen Sentinel-3 clouds and gaps

by jvaldezch » Fri Apr 09, 2021 4:43 pm America/New_York

Hi, I'm using L2gen OCSSW to process Sentinel-3 imagery in order to get Rayleigh-corrected reflectance but I realice that there are some gaps on resulting L2 images (left and right). See image below marked with red arrows.
s3_rhos_002.jpg
s3_rhos_002.jpg (330.55 KiB) Not viewed yet
Also I'm wondering if there is any recommedation to improve the cloud mask detection as you can see in the image below (CLDICE mask) the default parameters for L2gen removes a lot of data.
s3_rhos_001.jpg
s3_rhos_001.jpg (317.97 KiB) Not viewed yet
Thanks!

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OB.DAAC - SeanBailey
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Answers: 1

Re: L2gen Sentinel-3 clouds and gaps

by OB.DAAC - SeanBailey » Tue Apr 13, 2021 10:57 am America/New_York

The missing data on the edges is from the L1 data. If you look at the L1 file flags you'll see those edges are flagged as "invalid". It is a function of how the data are collected by the instrument. No getting around it :(

The cloud flagging for ocean color in l2gen is admittedly a bit conservative. The default flag is based on the reflectance (rhos) in a NIR band (865 for S3A). A threshold of 0.027 is used. you can change this by using the cloud_thresh option (pick a larger value to reduce the cloud mask).
You can also set maskcloud=0 to avoid masking data flagged as cloud. The cloud flag will still be set, but not masked at L2.

Regards,
Sean

jvaldezch
Posts: 26
Joined: Fri Aug 24, 2018 2:52 pm America/New_York

Re: L2gen Sentinel-3 clouds and gaps

by jvaldezch » Tue Apr 13, 2021 12:44 pm America/New_York

Thanks Sean.

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