MODIS Aqua L3 POC data_maximumchanged from ~12953 to ~1000 after July 2021: Processing update?

[h_hsy]

Hi OceanColor Team,
I would like to post a question on this forum regarding the downloaded MODIS Aqua Level 3 POC products. I noticed that for data before July 2021 (e.g., AQUA_MODIS.20180927.L3m.DAY.POC.poc.4km.nc), the data_maximum value is around 12953.4023, whereas starting from July 2021 (e.g., AQUA_MODIS.20200831.L3m.DAY.POC.poc.4km.nc), the data_maximum drops to approximately 1000.

Was there any specific data processing applied, or was a threshold reset during production? I couldn’t find any documentation explaining this change—perhaps I missed it. Could you please clarify this issue or point me to relevant references? Thank you!

[OB General Science - guoqingw]

Hello,

A mini-reprocessing was conducted for data from July 2021. Please refer to the following pages for more information:
https://oceancolor.gsfc.nasa.gov/data/reprocessing/r2022/aqua/

https://oceancolor.gsfc.nasa.gov/data/reprocessing/r2022.0.1/aqua/

As this mini-reprocessing affects Rrs, it also impacts the POC products. For additional details, please refer to the ATBD:
https://oceancolor.gsfc.nasa.gov/files/atbd/legacy/atbd-obdaac-particulate-organic-carbon.pdf

Best regards,
Guoqing

[h_hsy]

Dear Dr. Guoqing Wu and the OceanColor Team,
Thank you very much for your prompt reply and for directing me to the relevant announcement materials.
We truly appreciate your team for not only addressing inquiries but also for maintaining such comprehensive documentation. It is an invaluable resource for our research.
Best regards