VIIRS NOAA-21 CLDICE vs NOAA-20
Posted: Tue Feb 24, 2026 12:16 pm America/New_York
Hi,
It seems that CLDICE is not raised the same way for VIIRS NOAA-21 than for NOAA-20: with NOAA-21 strong clouds are not flag CLDICE, and also CLDICE seems not well flag in glint areas. On the other hand, the ATMFAIL flag is more raised with NOAA-21.
In our GlobColour project we calculate a Cloud Fraction (%) product based on CLDICE, and for NOAA-20 we obtain for example for 2025-08-15:
where for NOAA-21 we obtain:
Is it expected? If yes is it documented somewhere? I searched in reprocessing docs but found nothing.
Do you know if we can implement a workaround for NOAA-21 to have a CLDICE similar to NOAA-20?
Thanks for your help,
Julien
It seems that CLDICE is not raised the same way for VIIRS NOAA-21 than for NOAA-20: with NOAA-21 strong clouds are not flag CLDICE, and also CLDICE seems not well flag in glint areas. On the other hand, the ATMFAIL flag is more raised with NOAA-21.
In our GlobColour project we calculate a Cloud Fraction (%) product based on CLDICE, and for NOAA-20 we obtain for example for 2025-08-15:
Do you know if we can implement a workaround for NOAA-21 to have a CLDICE similar to NOAA-20?
Thanks for your help,
Julien