MODIS/Aqua-derived PAR data have many plaids

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machl
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MODIS/Aqua-derived PAR data have many plaids

by machl » Sun Jun 02, 2024 9:47 am America/New_York

Hello,

I used l2gen to process MODIS/Aqua L1A data to L2 data, all parameter settings were default, but the L2 PAR data have a lot of  plaids (an example is attached). How can I solve this problem?

What's more, the values of our L2 PAR data were about 10 einstein m-2 day-1 less than the L3 PAR data downloaded from ocean color, what's the reason?

Thanks for your help.
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A2002185060500_PAR.png
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OB.DAAC - SeanBailey
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Re: MODIS/Aqua-derived PAR data have many plaids

by OB.DAAC - SeanBailey » Mon Jun 03, 2024 10:40 am America/New_York

The PAR algorithm uses a coarse ancillary data field (9km resolution), and given the different grids of L2 and the L3 ancillary, the result can show as as bit patchwork. As for the magnitude differences, you should verify the inputs match exactly what our production system used.

Regards,
Sean

machl
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Re: MODIS/Aqua-derived PAR data have many plaids

by machl » Tue Jun 04, 2024 8:34 am America/New_York

Dear Sean,

Thank you very much for your helpful answer, as shown in the attached picture, I am curious why the west region seems not affected by patchwork.
Many thanks for your kind help.

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Re: MODIS/Aqua-derived PAR data have many plaids

by OB.DAAC - SeanBailey » Tue Jun 04, 2024 3:22 pm America/New_York

It is everywhere, but the color palette "hides" it. Look a the lower portion of your image and you will see the blocky pattern in the western side as well.

Sean

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