Beginning February 2006, MODIS Land users will notice a new implementation of Quality information on the EDG. As granules are returned from a search, the "Results:Granule:Listing" page will now display links to three quality flags; this replaces the single link to the quality metadata. The flags listed include "Automatic," "Operational," and "Science."
Users are advised to disregard the "Operational" quality information, as it is a defunct metadata field no longer used in MODIS production.
"Automatic" quality metadata indicate the successful production of a data granule. A failed AutomaticQualityFlag generally results from production errors, but some "errors" are triggered by proportional water content. This means data acquired over islands are often assigned failed AutomaticQualityFlags though the land data within is valid.
"Science" quality is assigned by the MODIS Land Science Team following evaluation of representative product samples; "ScienceQuality" is the most reliable quality flag. Most ScienceQualityFlags are set to "Passed," or "Inferred Passed," except in cases when spacecraft events interrupted data acquisition, or when data evaluation is in progress.
Examination of product quality bits is recommended for completely accurate quality assessment.
If you have questions, please contact LP DAAC User Services.