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VNP02DNB_NRT and VJ102DNB_NRT

Posted: Sun Aug 13, 2023 5:03 pm America/New_York
by patrickbnasa
Hi,

Our team uses VNP02DNB_NRT and VJ102DNB_NRT.

Beginning on or around August 7th (12 AM UTC) we have noted an apparent shift in the distribution of DNB data in both DNB_NRT products.

Specifically we are noting what appears to be increased levels of noise in the WATTAGE (DNB band) towards the extreme ends of the frame (x~=0, x~=4000). We have also noted what appears to be an increase in frames that have 256 values in the quality flag data of the same products (QF == 256 = Bowtie_Deleted/Range_bit), I do not know if these are related, and I do not have a simple strategy to quantify that increase.

Here is a sample URL showing this effect: https://ladsweb.modaps.eosdis.nasa.gov/archive/allData/5200/VNP02DNB/2023/223/VNP02DNB.A2023223.2254.002.2023224070645.nc

Has anyone else noticed this? Has there been any change to the processing of the imagery, beginning on or around August 7th, 2023?

Additional context below from the Tips guidance.
The date and time you accessed the above image: August 13, 1:54 PM (Pacific Time)
The general type of research you are conducting: Computer vision modeling
The name of the data product, data set, or data variable you were searching for: VNP02DNB_NRT and VJ102DNB_NRT
The access method you are using (browser, wget): a custom python application that downloads data via a the requests library (response = requests.get(url, headers=headers, timeout=600)) with the EarthData bearer token in the header
The platform you are using (mac, PC, linux) and operating system and the current version name and number: Linux (Ubuntu 22.04)
The application you were using (Giovanni, WMS, OPeNDAP, etc.): we are not using an application
Any significant error messages seen in your session: we have not noticed any error messages.

Re: VNP02DNB_NRT and VJ102DNB_NRT

Posted: Wed Aug 16, 2023 8:30 am America/New_York
by LAADS_UserServices_M
We feel like your note is inaccurate. We looked at the granule you suggested, and the QF is all fill, it is a night granule. We looked at a night granule from day 2023070 and it was the same way. Then we looked at a VNP02DNB from 2023223.2306, and it looks like one would expect. We are not seeing any excess 256 in it.
Also:
1. Are you seeing this in both NRT and STD products. If not, then why you are pointing to granules from https://ladsweb.modaps.eosdis.nasa.gov/..?
2. And, are you seeing this in both SNPP and J1?