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MODAPS PCR 24-004

PCR Number	24-004
Date	2024-07-17
Initiator	Sudipta Sarkar on behalf of Gary Lin (Geolocation) and Jack Xiong, Amit Angal/Kevin Twedt (MCST)
Abstract	PGE01 7.0.11, PGE02 7.0.18 (Terra), PGE02 7.0.17 (Aqua), PGE60 7.0.0 Major improvements implemented in the C7 L1 products include: Geolocation: Updated geolocation LUTs in pointing time series that correct for inaccurate predictions in the previous forward-processing Collection (and the slight differences in the errors measured by refresh chip library and old existing chip library). They are also extended to the end of the missions (2027). Updated Land Water Mask from a static database to year-by-year databases. Added a solar eclipse data field. L1B Calibrated TOA radiance/reflectance: Mission-long crosstalk correction applied to the Aqua PV LWIR & MWIR bands and Terra MWIR bands. Improved characterization of the VIS bands gains and RVS, especially in Terra MODIS by correcting the polarization effects on the desert data. Enhanced offset and non-linear coefficient estimation for several MODIS TEB Time-dependent RVS corrections in the Terra MODIS SWIR bands. For more details on C7 calibration changes, please refer to: https://mcst.gsfc.nasa.gov/calibration/collection-7 In addition to the above, all L1 products in C7 will be generated in NetCDF4 format, and with global metadata style changed from legacy ODL to "key-value" format.
Problem Statement	Generate improved version of the MODIS Collection 7 (C7) L1 Geolocation and calibrated Top of Atmosphere (TOA) products, in the first phase of C7 L1 reprocessing, from Terra Beginning of Mission (BOM) in 2000 to end of 2015
Description of Change	Major improvements implemented in the C7 L1 products include: Geolocation: Updated geolocation LUTs in pointing time series that correct for inaccurate predictions in the previous forward-processing Collection (and the slight differences in the errors measured by refresh chip library and old existing chip library). They are also extended to the end of the missions (2027). Updated Land Water Mask from a static database to year-by-year databases. Added a solar eclipse data field. L1B Calibrated TOA radiance/reflectance: Mission-long crosstalk correction applied to the Aqua PV LWIR & MWIR bands and Terra MWIR bands. Improved characterization of the VIS bands gains and RVS, especially in Terra MODIS by correcting the polarization effects on the desert data. Enhanced offset and non-linear coefficient estimation for several MODIS TEB Time-dependent RVS corrections in the Terra MODIS SWIR bands. For more details on C7 calibration changes, please refer to: https://mcst.gsfc.nasa.gov/calibration/collection-7 In addition to the above, all L1 products in C7 will be generated in NetCDF4 format, and with global metadata style changed from legacy ODL to "key-value" format.
Products Affected	C7 Geolocation (MxD03), Calibrated TOA (MxD02) and all downstream land and atmosphere products.
Software Affected	PGE01 7.0.11, PGE02 7.0.18 (Terra), PGE02 7.0.17 (Aqua), PGE60 7.0.0
Processing String to Receive the Change	Terra and Aqua Reprocessing.
Downstream Product Effects	All C7 MODIS Land + Atmosphere products.
Data Granules to be Used for Science Testing	Series of science tests were run in AS 1934, 1951, 1959, 1969 etc., to confirm all the changes made to the C7 PGE01 and PGE02, and associated LUTs, and validate their impacts on the land and atmosphere products.
Justification	The MODIS C7 processing is seen as the last opportunity to get in all the major changes for Terra and Aqua that may have become mandatory, given the respective drifts over the mission period, increasing optical and electronic crosstalk across different bands and detectors, increasing impact of Terra mirror side polarization effect, and orbital drift, following Terra constellation exit and discontinuation of all Terra/Aqua IAM and DMU maneuvers. Hence, major changes were put in the L1 Geolocation and calibrated TOA products, to address these concerns. The C7 Geolocation and downstream land products can now take advantage of a dynamic annual land water mask (LWM) product, replacing the static and old LWM that was in use for all earlier collections, allowing for better capturing of changes over the years, especially along the coastlines. In addition, MODIS C7 will break away from legacy HDF4 product formats, in favor of NetCDF4, which is more popular with climate data science community.
Effective Date for Implementation of Change	The PGEs and Recipes mentioned here will be used to initiate the C7 L1 reprocessing, for the 2000 ? 2015 period, starting the week of July 29, 2024.
Status	Gary Lin 07/17/2024, S. Platnick 07/19/2024, Sadashiva Devadiga 08/14/2024, Miguel Roman 08/14/2024, Sudipta Sarkar implemented on 07/17/2024.