MODIS Atmosphere
MODIS Atmosphere Home Products  Images  Validation  News  Staff  Forum  Reference  Tools  Help
Aerosol Product  Water Vapor Product  Cloud Product  Atmosphere Profile Product  Cloud Mask Product   Joint Atmosphere ProductLevel-2 Products
Daily Global Product  Eight-Day Global Product  Monthly Global ProductLevel-3 Products       Filled Land Surface Albedo ProductFilled Normalized Difference Vegetative Index ProductOne-Minute Land Ecosystem Classification ProductLevel-3 Ancillary Land Surface Products
Format & Content
Ancillary Input
Grids & Mapping
Sample Images
QA Information
Product Modification History
Acquiring Data
Filename Convention
Analysis Tools
Theoretical Basis
Detailed File Spec
Algorithm Software
Production Plan
Support Team


General PGE Information

The MOD06_L2 and MYD06_L2 products are produced from the Program Executable (PGE) identified as PGE06. To determine the current PGE06 version that has completed: 1) baseline procedure, 2) integration & testing, and 3) MODAPS operations implementation, visit the PGE Status Chart. For information on reconciling Algorithm process version and PGE version, visit the PGE06 Version History File.

Tool/Command for PGE Determination

One may identify the maturity and quality of an HDF data product by finding the PGE (program executable) version that was used to produce the file. This information can be obtained directly from the HDF file itself by using the HDF utility ncdump. The (UNIX) command for finding the PGE version that was used to create a particular HDF file is

ncdump -h *.hdf | awk '/PGEVERSIONCLASS/,/END_GROUP/'

One may also find PGE version information in the ascii met (metadata) file associated with a particular HDF file.

PGE06 Algorithm History - Product Impact Changes

  • Cloud Optical Products (06_L2)


      Platform: Aqua
      Product Generation Executive (PGE): PGE06 v6.0.72
      Archive Production Time Period: 7/2002-12/2012

      The intended maximum reported value for a successful Cloud Optical Thickness (COT) retrieval was increased from 100 in Collection 5 to 150 in Collection 6 (C6). However the new C6 COT datasets Cloud_Optical_Thickness_16 and Cloud_Optical_Thickness_37 were inadvertently not limited to 150. Therefore, for a small number of very bright clouds (typically at low sun angles), these two COT datasets can exceed 150 or become negative due to an integer overflow (beyond a value of 327.67). Users are advised that if they encounter a COT value in these datasets that is either greater than 150, or less than zero but not a fill value, then they should set the value to 150.


      Platform: Aqua
      Product Generation Executive (PGE): PGE06 v6.0.75
      Archive Production Time Period: 1/2013-present

      This minor COT dataset issue has been remedied for Aqua forward processing starting on a production date of April 21, 2014 (2014111). Since the problem was found before Terra reprocessing began, no Terra re-/forward-processing was impacted.