MODIS Collections and Other News
Decommissioning of the MODIS C6 Forward Processing (01/26/2023)
C6 Forward processing of Terra and Aqua MODIS Land data products will be discontinued, on or around mid-February 2023 (02/15/2023). The C6 land data products have always suffered from known calibration issues that were discovered by the instrument Cal/Val team after the completion of the C6 reprocessing. The main among these being the increased impact of optical crosstalk in the Terra PV LWIR bands 27-30, that had made retrieval of most atmospheric parameters infeasible, indirectly impacting some of the land products that were dependent on these atmospheric retrievals. The Collection 6.1 (C61) corrects for this and some other critical calibration issues and also has a number of product specific improvements and enhancements that are listed in the C61 change document here.
Given the improved performance and calibration of C61, users are requested to switch to C61 for all of their MODIS land data needs. DAACs, will retain the C6 historical land data products for a further period of 6 months, following this decommissioning of the C6 forward processing, and will decommission all C6 land data products after the expiry of this 6-month retention period.
Upcoming Terra Constellation Exit
Terra is scheduled to exit the 'Morning Constellation' of Earth Science satellites by October, 2022. Because of onboard fuel shortage, the last of Terra mission maneuver was done on February 27, 2020 to maintain the mean local time (MLT) of 10:30 AM. Thereafter, Terra has been drifting slowly from its MLT and will reach and exceed 10:15 AM MLT by October 2022, when it will make the constellation exit with a lowered orbit altitude of 694kms. More information can be found here.
MODIS C6.1
C61 reprocessing of Land products, with minor changes to the land algorithms using the C6.1 L1B as input, began in February 2020 with the exception of the MAIAC, VCF, Land cover and Phenology products. MODAPS is currently testing the MAIAC algorithm and is integrating code for the Land Cover and Phenology products. MODAPS is still awaiting delivery of the VCF algorithm.
Public release of C6.1 products began in Febuary 2021 and the plan is to complete reprocessing the entire archive by the end of 2021.
Note: The C6 Terra MODIS products, particularly the cloud products, were negatively impacted by optical crosstalk in the infrared bands (B27 – B30). Though the crosstalk issue was present from the beginning of the mission, its impact on the products were not significant until after year-2009, and became even more so following the MODIS Terra safe-hold in February of 2016. The C6.1 reprocessing implemented an approach to correct this crosstalk issue in the calibration from the beginning of the mission.
MODIS C7
Collection 7 L1B changes to calibration have been delivered by MCST. The calibration testing with downstream products is in progress.
After the evaluation of the L1B calibration testing by the discipline teams, operational C7 geolocation and L1B processing is planned for mid 2022. The atmosphere and land products will not begin C7 reprocessing until early 2023.
C7 reprocessing will use an annual Land/Water Mask (LWM). This new LWM will be incorporated into the geolocation product.
All the products in this collection will be in netCDF4 format.
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