How to read new MERIS L1 data?

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eliteqing
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How to read new MERIS L1 data?

by eliteqing » Tue Oct 26, 2021 2:58 pm America/New_York

Hello, I tried to download some MERIS FRS Level1 image files from: "https://oceandata.sci.gsfc.nasa.gov/dir ... /MERIS/L1/" but not able to open it.
After unzip and try to load "xfdumanifest.xml" file into ESA SNAP software, it shows error:
"no appropriate product reader found. File ...xfdumanifest.xml cannot be opened"
The zip file of same name from ESA online data hub can be read via the same software. I need to use SNAP to be combined with other existing processing.

I see the Oceancolor folder says: "MERIS data existing at the OB.DAAC are from the 3rd reprocessing of the instrument. However, a more current dataset is available. To obtain those data, please visit ESA’s Online Dissemination Service for MERIS. To continue with data from the 3rd reprocessing, search below." but I see the file name conventions is consistent with that from ESA, and modified date April 2021 which I feel the file is up-to-date. I also checked the both files from here and ESA have version: <sentinel-safe:software name="MEGS-L1" version="9.6"/>

any clue?
by OB SeaDAS - xuanyang02 » Wed Oct 27, 2021 12:42 pm America/New_York
We fixed the bug, so SeaDAS-8.1.0 can read both L1 files from NASA site and ESA site. You can try SeaDAS-8.1.0 https://seadas.gsfc.nasa.gov/downloads/

SNAP also accepted the fix, and hopefully it will be included in their next release.
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OB.DAAC - SeanBailey
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Re: How to read new MERIS L1 data?

by OB.DAAC - SeanBailey » Wed Oct 27, 2021 10:30 am America/New_York

Yes, we have since updated the L1B data to the 4th reprocessing, but the L2 and L3 data are still based on the 3rd reprocessing inputs. A reprocessing is in the works to regenerated the L2 and L3 data based on the newer L1B data. We will adjust the banner to clarify this.

It seems that the SNAP reader doesn't like the directory name that the ZIP files from our archive are extracted into. The data ARE exactly the same as the those from the ESA archive. The xfdumanifest.xml file has a productName element that matches the ESA zip extract directory. If you change the unzipped directory name from the OBDAAC file to match this name, the reader works.

We'll look into the reader to see why it matters (it shouldn't), but until we can resolve this in the code the solution is to change the directory name.

Sean

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Re: How to read new MERIS L1 data?

by OB SeaDAS - xuanyang02 » Wed Oct 27, 2021 12:42 pm America/New_York

We fixed the bug, so SeaDAS-8.1.0 can read both L1 files from NASA site and ESA site. You can try SeaDAS-8.1.0 https://seadas.gsfc.nasa.gov/downloads/

SNAP also accepted the fix, and hopefully it will be included in their next release.

eliteqing
Posts: 2
Joined: Tue Oct 26, 2021 2:48 pm America/New_York

Re: How to read new MERIS L1 data?

by eliteqing » Sat Oct 30, 2021 1:32 pm America/New_York

Thank you Sean and XuanYang!
problem solved and look forward to the new version of SNAP and SEADAS.

OB SeaDAS - xuanyang02
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Re: How to read new MERIS L1 data?

by OB SeaDAS - xuanyang02 » Mon Nov 08, 2021 11:40 am America/New_York

SNAP just released S3tbx 8.0.4. You will be prompted for updates when you start SNAP, or you can do Help -> check for updates and update from there. Once you update, you should be able to read both L1 files from NASA site and ESA site in SNAP

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