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VALIDATION
04_L2 Known Problems
05_L2 Known Problems
06_L2 Known Problems
07_L2 Known Problems
35_L2 Known Problems
ATML2 Known Problems
08_D3 Known Problems
08_E3 Known Problems
08_M3 Known Problems

Known Problem Summary

Tracking of known problems and subsequent fixes is an important issue for MODIS data users. This page will act as a repository of all known MODIS Atmosphere Data Product problems, as well as how to determine the problematic version (and the fixed version) of the HDF data -- therefore data users should check this page for updates regularly. Data Users unfamiliar with how to properly track problems and fixes by determining the version of their downloaded HDF files should refer to the documentation at the bottom of this page.      

Collection 006 Issues

Click the colored buttons below for the known problems associated with each MODIS Atmosphere Data Product in Collection 6.

Click to see 04_L2 Known Problems Click to see 05_L2 Known Problems Click to see 06_L2 Known Problems Click to see 07_L2 Known Problems Click to see 35_L2 Known Problems Click to see ATML2 Known Problems Click to see 08_D3 Known Problems Click to see 08_E3 Known Problems Click to see 08_M3 Known Problems


  • Two Minor Issues in Aerosol 3km (04_3K) Data

    Description: The Aerosol Team uncovered and then fixed a few issues in the MOD04_3K (3km) Aerosol Product. The problems are:

    1. Bad Scan Start Time: Scan_Start_Time SDS issue for Aerosol 3km (04_3K) has been resolved and the current forward processing will be correct.
    2. Bad Aerosol Cloud Fraction (Land and Ocean): Incorrect values in 'Aerosol_Cloud_Fraction_Land' and 'Aerosol_Cloud_Fraction_Ocean' SDSs for the Aerosol 3km product (04_3K), there was a bug in the code resulting in both SDSs being filled with only zeros and ones. This bug has been resolved, and the current forward processing will be correct.

    Impact: Low

    Data Dates Affected: 7/2002-current

    Platform Affected: Aqua Only

     
    PGE Version Production Dates   PGE Version Production Dates
    ≤ PGE04 v6.0.43 ≤ 2014 313 (11/09/2014)   ≥ PGE06 v6.0.44 ≥ 2014 314 (11/10/2014)


  • Three Minor Issues in Aerosol 10km (04_L2) Data

    Description: There are three known problems in 04_L2 (10km res.) and 04_3K (3km res.) files for Collection 6. None of these problems are planned to be fixed at this time, but could be fixed in a future delivery. The problems are:

    1. Non-populating Mean_Reflectance_Ocean SDS in some scenerios (04_L2): The SDS Mean_Reflectance_Ocean is not populating when Aerosol_Optical_Depth = 0.
    2. Long Name descriptor omission (04_L2): There is an omission in the "long_name" local attribute for one parameter: PSML003_Ocean. It should be noted that this abbreviated SDS name is an acronym for "Particles of the Small Mode Aerosol larger than 0.03 microns". The long_name currently reads "Inferred column number concentration (number per area) of particles larger than 0.03 micron for 'best' (1) and 'average' (2) solutions"; and it should read "Inferred column number concentration (number per area) of particles of Small Mode Aerosol larger than 0.03 micron for 'best' (1) and 'average' (2) solutions".
    3. Scan_Start_Time SDS issue for 3km Aerosol (04_3K): For the Aerosol 3km Product (04_3K), there is a bug in interpolation routine to compute SDS “Scan_Start_Time”, causing some incorrect values. Scanline 1 in the 04_3K granule has the correct start time. However an interpolation error causes the start time to increment too fast for subsequent scans, and by the end of the 04_3K granule, the start time is off by nearly 7000 seconds (nearly 12 minues).

    Impact: Low

    Data Dates Affected: 7/2002-current

    Platform Affected: Aqua Only

     
    PGE Version Production Dates   PGE Version Production Dates
    ≤ PGE04 v6.0.39 ≤ Current Date   (Not Corrected) (Not Corrected)







Latest PGE Version Available (by Data Date)

Shown below is a bar chart graphic summarizing the latest Product Generation Executive (PGE) Version used to produce Collection 6 (C6) 04_L2 HDF files available for public distribution (download) in the LAADS data archive. This graphical representation gives MODIS data users a summary guide (digestable at a glance) on how the PGE Version varies across the multi-year data record. Each PGE version contains a unique set of fixes and improvments and show where data quality discontinuities can occur. If MODIS data users have older versions of any of the data shown below, they should download the newer (more correct) version from either: LAADS FTP (Download C6 MYD04_L2 Data) or LAADS Web (Search & Order MODIS Data)

Aqua:

     








How to Track MODIS Data File "Versions" (Important for Tracking Problems and Fixes)

Problems and fixes in MODIS Atmosphere Product HDF files can be tracked in one of two ways:

  1. the Product Generation Executive (PGE) Version Number that can be queried from any HDF file using the command:
      ncdump -h *.hdf
  2. the HDF File "Production Date".

The HDF File "Production Date", which is the date the HDF file was actually generated or produced, can be found in the HDF filename itself (shown in green color below):
Level 2 Product Names:

 Level 3 Product Names:

Note that 1.) all times are UTC time, not local time 2.) the DDD in the date denotes the Julian Date (001-366), and 3.) the MOD06_L2 (or MOD08_D3) prefix is only an example (MYD04_L2, MOD05_L2, MYD05_L2, MYD06_L2, etc. ... or MYD08_D3, MOD08_E3, MYD08_E3, MOD08_M3, MYD08_M3 could be substituted).