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


Data Volume

The MODIS Atmosphere Cloud Product (MOD06_L2) will be produced at the MODAPS facility at the NASA Goddard Space Flight Center.

MODAPS will produce 100% of the MOD06_L2 product.

Approximately 288 MOD06_L2 HDF files are produced per day, however since only the Cloud Top Properties Algorithm is run during the nighttime hours, the nighttime HDF files are considerably smaller than their daytime counterparts. Since both MODIS terminator granules (for both ascending and descending nodes) are counted as day, a full 55% of all MODIS granules are labeled day-time.

With each daytime HDF file roughly 65.1 MB in size and each nighttime HDF file roughly 12.4 MB in size, the total data volume is approximately 12.3 GB per day.

Production Rules

Cloud Top Process (MOD_PR06CT)

MOD_PR06CT executes 24 hours a day (on every MODIS L1B granule). The required input MODIS Products are:

  • MODIS L1B 1km Product (MOD021KM)
  • MODIS Geolocation Product (MOD03)
  • MODIS Cloud Mask (MOD35_L2)

The MOD_PR06CT process also requires ancillary data and a processing delay of up to 12 hours is allowed for the acquisition of these data. MOD_PR06CT requires the atmosphere ancillary data GRIB files and SST Reynolds blended file to be staged in the correct Logical Unit Numbers (LUN's) in the Process Control File (PCF). The NCEP GDAS final run product must be staged in LUN 900000, the TOVS total column ozone product (1 time daily) must be staged in LUN 900020 and the NCEP half-degree ice concentration file must be staged in LUN 900040. In addition the Reynolds blended SST ASCII file must be staged in LUN 1000030.

The ancillary data should be staged that is the closest match to the L1B file data. The files are available 4 times per day. The actual ancillary data products can be located at:

  • NCEP daily ice concentration data GRIB file
    FTP site (example: eng.YYMMDD)
  • NCEP 6-hourly GDAS1 meteorological data GRIB file
    FTP site (example: gdas1.TXXZ.PGrbF00)
  • NCEP daily TOVS total ozone GRIB file
    FTP site (example: YYMMDD.grb)
  • NCEP weekly Reynolds SST ASCII file
    FTP site (example: oi.mean.b)

In addition, the MOD_PR06CT process has some static file staging requirements. Processing is not allowed to initiate until these data are staged. These required static files are:

  • 1km North America ecosystem map
  • 10 minute Global ecosystem map
  • Five BINARY coefficient files:
    1. Dry gas coefficient file (modisdry.pfm)
    2. Ozone coefficient file (modisozo.pfm)
    3. Wet atmosphere coefficient file1 (modiswts.pfm)
    4. Wet atmosphere coefficient file2 (modiswtl.pfm)
    5. Water vapor continuum coefficient file (modiswco.pfm)

Cirrus Detection Process (MOD_PR06CD)

The MOD_PR06CD production rules are:

  • Run MOD_PR06CD on every MODIS L2 granule if, at the time all required inputs are expected, all are actually present. Otherwise, wait until required inputs arrive.
  • MOD_PR06CD queries the DayNightFlag in MOD03 at the start of every execution. If the DayNightFlag is 'Night', MOD_PR06CD will exit immediately (code 0) writing no data or metadata to the MOD06_L2 product file. Otherwise, MOD_PR06CD continues and performs retrievals of cirrus reflectance and contrail index. These science data as well as metadata updates are appended to a pre-existing MOD06_L2 HDF product, first produced by MOD_PR06CT (MOD_PR06CR in future version) running in the same PGE06.

The required input MODIS products are:

  • MODIS L1B 1km Product (MOD021KM)
  • MODIS Geolocation Product (MOD03)
  • MODIS Cloud Mask (MOD35_L2)

The required input static file is:

  • Water Vapor Transmission Table at 1.38 microns (TRANSM_H2O_1P38_MICRON.v1)

Cloud Optical (Depth) Process (MOD_PR06OD)

The MOD_PR06OD production rules are:

  1. Run MOD_PR06OD for each MODIS L2 granule if, at the time all required and optional inputs are expected, all are actually present.
  2. If required inputs are absent, wait until they arrive.
  3. If optional inputs are absent, wait six hours beyond the expected time and then run.

The required input MODIS Products are:

  • MODIS L1B 1km Product (MOD021KM)
  • MODIS Geolocation Product (MOD03)
  • MODIS Cloud Mask (MOD35_L2)

The input ancillary Products are:

  • One degree NCEP GRAS data (GDAS_0ZF)
  • Once daily TOVS ozone (OZ_DAILY)
  • Reynolds weekly sea surface temperature product (REYNSST)
  • NCEP ice concentration on 1/2 degree lat/lon projection (SEA_ICE)

Note that at-launch NCEP ancillary data will be used. Post-launch will switch to DAO ancillary data. These DAO parameters are used to compute average column air temperature and total precipitable water, above cloud. Post-launch DAO ancillary details:

  • 6 Hourly Instantaneous Temperature Profile (TMPU)
  • 6 Hourly Instantaneous Specific Humidity (SPHU)
  • 3 Hourly Averaged Ground (Surface Skin) Temperature (TGROUD)

The input static files are:

  • Algorithm control file (inf_v2.dat.v1)
  • Water flux libraries
    • flux_ts040_water.dat.v1
    • flux_ts080_water.dat.v1
    • flux_ts120_water.dat.v1
    • flux_tsinf_water.dat.v1
  • Water reflectance libraries
    • refl_ts040_water.B.v1
    • refl_ts080_water.B.v1
    • refl_ts120_water.B.v1
    • refl_tsinf_water.B.v1
  • Ice flux libraries
    • flux_ts040_ice.dat.v1
    • flux_ts080_ice.dat.v1
    • flux_ts120_ice.dat.v1
    • flux_tsinf_ice.dat.v1
  • Ice reflectance libraries
    • refl_ts040_ice.B.v1
    • refl_ts080_ice.B.v1
    • refl_ts120_ice.B.v1
    • refl_tsinf_ice.B.v1
  • CERES surface scene map

The optional input products are:

  • Near Real-Time SSM/I EASE-Grid Daily Global Ice Concentration and Snow Extent product produced at NSIDC (NISE)

Note that MOD_PR06OD will run and execute successfully without the optional input, but the resultant MOD06_L2 data product may be of inferior quality.