VIIRS daily (VNP09GA) 500m quality flags

[martinkeller]

I am currently reviewing the daily VIIRS reflectance data, VNP09GA, described in the technical documentation (https://lpdaac.usgs.gov/documents/1657/VNP09_User_Guide_V2.pdf) and I made good progress obtaining example images at 1km resolution and filtering these using the provided quality flags at this resolution.

I am currently looking into the 500m resolution data and I am not entirely sure whether there quality flags are available at this resolution, or if have to use the 1km quality flags for this data as well.

Any advice would be much appreciated.

[LP DAAC-EDL - lien]

Hello,
Yes, that is correct, as those are the only QA that directly pertain to that product. It is not unlike the MOD09GA where they suggest using the 1-kilometer State flags over the Band QA. Please let me know if you have any questions.
Thanks,
Brett

[sebastien.lenard]

Hi!
I'm jumping into this thread, because I have similar questions.

- "the MOD09GA where they suggest using the 1-kilometer State flags over the Band QA" Is this indicated in the mod09ga doc or elsewhere?

- For vnp09ga, there's no flag equivalent to mod09ga/QC_500m flags: modland, atmospheric correction, and adjacent correction. Is that information contained or synthesized in other flags at 1 km in vnp09ga?

Thank you!
Sebastien.

[LP DAAC-EDL - dgolon]

Hi all -- we recently heard further information on this topic:

There are no MODIS equivalent state flags in the VIIRS L2G lite products, but you should be able to glean the same set of information by referring to the SurfReflect_QF[1-7] flags. Those provide all the information that can be found under the MODIS State flags.

Also, note that the there is no VIIRS equivalent of the MODIS MODLAND QA flags, for any VIIRS product. That was discontinued for VIIRS. The MODLAND just summarized all QA information but different critical QA flags like Atmosphere correction, cloud and snow cover, land/water class, band quality, etc. can be combined as needed, and then you can create your own rules of accepting or rejecting a given observation.