PAR

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pastora
Posts: 1
Joined: Sat May 29, 2021 12:20 am America/New_York

PAR

by pastora » Sat May 29, 2021 12:37 am America/New_York

Hi,
Which factors can affect the values of PAR? ...
Is there any effect of turbidity parameters in the water column (like Kd490) on PAR?
And what could be the reasons for missing monthly data?

Thanks for having this forum
Pastora

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gnwiii
Posts: 642
Joined: Fri Jan 29, 2021 5:51 pm America/New_York
Answers: 2

Re: PAR

by gnwiii » Tue Jun 01, 2021 11:16 am America/New_York

Is the missing data found in high latitude winter? Which sensor are you using?

In my area (Northwest Atlantic) PAR is missing in areas of seasonal ice. The algorithm can't differentiate between bright pixels caused by cloud and bright pixels caused by surface conditions, so it relies on ancillary data for ice cover.
Since you mention monthly data, I assume you are working with level-3 files. You may find it instructive to gather all the level-2 files for an area with missing data so you can examine level-2 flag values (e.g., using the SeaDAS 8 GUI) for a few pixels that are missing data.

SeaWiFS coverage was shifted seasonally away from the winter pole, so if you are using SeaWiFS data there won't be any data for polar winter areas.

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