Introduction
Collection 5The MODIS data from the Terra and Aqua satellites are being reprocessed using revised algorithms beginning in September 2006. This new set of MODIS Products is called Collection 5.
To view the product changes that took place in going from Collection 4 to Collection 5, please visit the following Web site: http://landweb.nascom.nasa.gov/cgi-bin/QA_WWW/newPage.cgi?fileName=MODLAND_C005_changes
The ORNL DAAC provides subsets of the Collection 5 MODIS Land Products. Investigators from around the world have shown a great deal of interest in this activity, asking that over 1000 field and flux tower sites be included in Collection 5 subsetting (up from 280 sites for Collection 4 MODIS subsetting).
Availability of the Collection 5 Data Products
For Collection 5, data from the Terra and Aqua satellites will be reprocessed at a rate of roughly 4 days of data acquisition for each calendar day. The backward reprocessing started in Fall 2006 with data collected in February 2000. Because of the rate of processing the MODIS record for February 2000 through December 2006 will not be available until September 2008.
If you have downloaded MODIS products in the past, you may want to check our log of activities to determine if you need to replace your older data. Because new data are added each week, you may want to revisit our Web site for the most recent data.
Collection 4
The Collection 4 processing ceased at the end of December 2006. Currently, Collection 4 subsets from Terra are available for the period February 2000 through December 2006 and subsets from Aqua are available for the period June 2002 through December 2006.
Collection 4.8 Reprocessing for the MOD17 Products
The MODIS 17 team (Steve Running, lead, University of Montana) has applied several corrections to the MOD17 algorithms, resulting in a new Collection 4.8 suite of products. These corrections are applied to the upstream data product (MOD15A2, LAI / fPAR) and to the meteorology.
Briefly, the MOD15A2 product has been modified by using temporal interpolation to replace pixels that have QC flags indicating poor quality. A new and temporally consistent meteorology has been developed for the MOD17 products.
Please note that these changes cannot be made in a forward-processing mode, and are currently being made at the end of each calendar year. Currently data for 2000, 2001, 2002, 2003, 2004, and 2005 are available in Collection 4.8.
Gap Filled and Smoothed MODIS Land Products
We also offer subsets gap-filled and smoothed MODIS Land products specially processed for modeling activities associated with the North American Carbon Program (NACP). MODIS-for-NACP provides a gap-filled and smoothed version of the LAI / fPAR Product, which is called MOD15A2GFS.