The MODIS Adaptive Processing System (MODAPS) is currently generating an improved Collection 6.1 (C6.1) for all MODIS L1 and higher-level atmosphere products, and plans to generate C6.1 for all the land products in the near future. This decision is driven by the need to address the following issues in the current MODIS C6 version of the products:
1. Changes to Level-1B (L1B) calibration:
- Change to Response-versus-Scan angle (RVS) approach that affects reflectance bands for Aqua- and Terra-MODIS: A change in the RVS approach that uses fixed desert sites was implemented in C6 for Terra-MODIS from the beginning of the mission (Feb 2000) and for Aqua-MODIS from July 27, 2016 and onwards. The C6.1 reprocessing will apply this change in RVS approach to calibration of reflectance bands from the beginning of the Aqua mission as well.
- Correction to adjust for the optical crosstalk in Terra-MODIS infrared (IR) bands: The C6 MODIS Terra products, especially cloud products were negatively impacted by the optical crosstalk in IR bands (B27 - B30). Though the crosstalk issue was present from the beginning of the mission, its impact on the product wasn't significant, and not noticeable until after year-2009. The C6.1 reprocessing implements an approach to correct this crosstalk in the calibration from the beginning of the mission.
- Correct the Terra-MODIS forward-Look-up Table (LUT) update for the period 2012 - 2017: The C6 Terra L1B data products from the period 2012 through January 2017 were generated using faulty calibration LUTs because of an error in the process generating the routine forward-LUT updates by the MODIS Characterization Support Team (MCST), which was fixed in January 2017. This error affected bands 1 and 2 only.
2. Minor algorithm changes to the Level-2 and -3 MODIS atmosphere products:
- MOD35_L2 (Terra MODIS Cloud Mask 5-Min L2 Swath 250 m and 1 km) - Improved Cloud Mask retrieval from the crosstalk correction in MOD021KM products.
- MOD04_L2 (Terra MODIS Aerosol 5-Min L2 Swath 10 km) & MOD04_3K (Terra MODIS Aerosol 5-Min L2 Swath 3 km):
MOD06_L2 (Terra MODIS Cloud 5-Min L2 Swath 1 km and 5 km):
- Improved Dark Target Aerosol retrieval over urban areas
- Improved uncertainty estimates for Deep Blue Aerosol retrievals
- Updated Cloud Optical Property retrieval using C6 gap-filled surface albedo
- Improved Cloud IR phase and Cloud Top Property retrieval from the crosstalk-corrected radiances in MOD021KM products
Consult the following URL to access detailed documentation on the C6.1 changes in the MODIS atmosphere products:
C6.1 Reprocessing and Forward-processing plan for L1 and atmosphere products:
- The reprocessing of C6.1 Terra-MODIS L1 and atmosphere products, which is currently in progress, starts from the beginning of the mission in February, 2000, and is expected to complete by the end of 2017.
- Following the completion of the Terra-MODIS L1 and atmosphere products, the reprocessing of Aqua-MODIS L1 and atmosphere products will start.
- The forward-processing of C6.1 Terra- and Aqua-MODIS L1 and atmosphere products started at the same time on September 1, 2017.
C6.1 Reprocessing and Forward-processing plan for land products:
- Based on current estimates, the reprocessing and forward-processing of Terra- and Aqua-MODIS land products is slated to begin sometime around the middle of 2018 timeframe.
MODIS C6.1 Release Schedule (Updated)
| MODIS Level-1 products
||October 15, 2017
| MODIS Atmosphere products
||October 15, 2017
| MODIS Land products
Retention of C6 MODIS atmosphere products:
The C6 forward-processing of Terra- and Aqua-MODIS atmosphere products will continue in parallel with the C6.1 collection through the end of 2017; at that time, we may discontinue the C6 processing stream with only the C6.1 stream being produced. However, we will continue providing access to the C6 collection, via LAADS, for another six months, and likely schedule their decommissioning beyond that time. Please watch these alerts for further updates.