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MODAPS PCR VNP 24-020

PCR Number	VNP 24-020
Date	2024-02-04
Initiator	Carol Davidson
Abstract	PGE554 2.0.15 Revised NPP_PRDNBdaily/DNBdaily_main.c in C2 version of PGE554 to fix UTC_time for the case obscov_1=0 (set wt=1). This change will prevent an unwanted divide by zero and therefore the "Nan" UTC value is prevented.
Problem Statement	C2 Daily gridded DNB/CM, VNP46A1, for day 2018-331, the h26v06 tile, was found to have a "NaN" UTC value which causes downstream daily LBAN (VNP46A2) to fail to process the data. Investigation of issue found bad value was caused by a bad divide by zero.
Description of Change	Revised NPP_PRDNBdaily/DNBdaily_main.c in C2 version of PGE554 to fix UTC_time for the case obscov_1=0 (set wt=1). This change will prevent an unwanted divide by zero and therefore the "Nan" UTC value is prevented.
Products Affected	VNP46A1, VJ146A1 and VJ246A1
Software Affected	PGE554 2.0.15
Processing String to Receive the Change	S-NPP Forward Processing. J1 Forward Processing. J2 Forward Processing. J2 Reprocessing. NRT
Downstream Product Effects	All VIIRS land products.
Data Granules to be Used for Science Testing	A science test was conducted of PGE554 2.0.15-0 in AS4067 and results reviewed by LDOPE and the LBAN science team. No unexpected differences were found, and the desired change was present.
Justification	Correction requested by LDOPE after review of data found the discrepancies for assorted dataset attributes.
Effective Date for Implementation of Change	PGE554 2.0.15 was put into use for C2 NPP and JPSS1 leading edge starting 2/4/25, and JPSS2 extended test archive starting 2/5/25, as well as the NRT3/4 machines for start use 2/5/25. No reprocessing is to be done with this version of PGE554 except for the NPP 2018-331, the h26v06 tile to correct the bad data. No other reprocessing to be done with this revision.
Status	Major algorithm development completed. Sadashiva Devadiga approved 2/12/2025. Sudipta Sakar implemented 2/11/2025.