Detailed Description

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Case #:PM_MOD13_16301   Opening date: 10/27/16   Last update: 01/04/18
Status: Pending
Due to a software bug some of the VI retrievals are flagged as good in the MODLAND QA bits (bits 0-1 = 00) within the 16-day Composite VI Quality SDS, with lowest score of 15 in the sds VI_Usefulness. A software patch is currently under testing and is expected to be operational in the forward processing soon. The following example shows images of a spatial subset of 16-day composite NDVI on left followed by corresponding subsets of the 'MODLAND QA' bits in the '16-day VI Quality' datasets in the middle and the 'VI usefulness' dataset on the right side. The black stripe in the image of 'VI usefulness' corresponds to value 15, the lowest usefulness score. The corresponding pixels in the 'MODLAND QA' has value '0' indicating good VI retrievals.

NOTE: This issue has been resolved in the C6 forward processing from day DOY 2017.241 and onwards.

Spatial Subset

MODLAND_QA, bits [0-1]
Green:0:VI produced, good quality
Yellow:1:VI produced, but check other QA
Blue:2:Pixel produced, but most probably cloudy
Dark Blue:3:Pixel not produced due to other reasons than clouds
Spatial Subset

VI usefulness, bits [2-5]
Green:0: Highest quality
Yellow:1: Lower quality
Orange:2 to 10: Decreasing quality
Red:12: Lowest quality
Magenta:13: Quality so low that it is not useful
Purple:14: L1B data faulty
Black:15: Not useful for any other reason/not processed
Spatial Subset

Occurrence: All MOD13 products from the C6 reprocessing. From beginning of mission to DOY 2017.241

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