MODIS Aqua SST and Chl-a Product

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febryanto25
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MODIS Aqua SST and Chl-a Product

by febryanto25 » Wed May 05, 2021 1:11 am America/New_York

I just downloaded monthly SST day time data MODISA_L3m_SST_Monthly_4km_vR2019.0 from Giovanni, I found 'qual_flag' is one of the variable in addition to the SST product itself. What is the purpose of 'qual_flag' variable? Is this variable like a correction to the SST product or something? Do I need to consider this variable? If yes, how can I use this variable to correct the SST product?

I also downloaded monthly Chlorophyll-a data MODISA_L3m_CHL v 2018 from Giovanni. This product are processed by OCI or OCx algorithm?

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gnwiii
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Re: MODIS Aqua SST and Chl-a Product

by gnwiii » Wed May 05, 2021 1:25 pm America/New_York

The underlying SST quality variables are defined in the level-2 data (https://oceancolor.gsfc.nasa.gov/atbd/sst/). NASA uses binning and mapping to produce the monthly mapped products used by Giovanni. Because this process averages multiple pixels, it is necessary to exclude "low quality" pixels. https://oceancolor.gsfc.nasa.gov/forum/ ... l?tid=6554 or viewtopic.php?f=7&t=1100 has images produced with different settings along with some discussion.

GES DISC - jimacker
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Re: MODIS Aqua SST and Chl-a Product

by GES DISC - jimacker » Thu May 06, 2021 4:31 pm America/New_York

Giovanni receives the standard MODIS-Aqua chlorophyll-a (chlor_a) data product from the OBDAAC. The algorithm is described here:

https://oceancolor.gsfc.nasa.gov/atbd/chlor_a/

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