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MODIS Terra+Aqua BRDF/Albedo Quality 16-Day L3 Global 1km SIN Grid
One of the more significant differences between the V004 and V005 BRDF/Albedo data products is that the quality information is no longer embedded as a Science Data Set in each product. BRDF/Albedo Quality is now generated as stand alone data in a separate product, MCD43B2, which can be applied to the other BRDF/Albedo products externally through pixel matching.
The table below lists the four Science Data Sets represented in the Quality product, with their associated QC bit legends. This information is excerpted from the file specifications for V005 MCD43B2 found at ftp://modular.nascom.nasa.gov/pub/LatestFilespecs/collection5/.
The 1 kilometer BRDF/Albedo products are averages of the 500 meter values found in the MCD43A products. Thus snow free and snow covered 500-m pixels are averaged together and if any of the 500-m pixels were snow-covered the 1km is flagged as snowy.
*NOTE: The first two Quality SDSs (BRDF_Albedo_Quality and Snow_BRDF_Albedo) are not bit packed. They are complete byte words that can be read directly.
| Byte Word | BRDF_Albedo_Quality* |
| 1 | Processed, see other QA (magnitude BRDF inversions) |
| 0 | Processed, good quality (full BRDF inversion) |
| 255 | Fill Value |
| Byte Word | Snow_BRDF_Albedo* |
| 1 | Snow albedo retrieved |
| 0 | Snow-free albedo retrieved |
| 255 | Fill Value |
| Bit Comb. | BRDF_Albedo_Ancillary |
| 00-03 | Platform |
| 0 | Terra |
| 1 | Terra/Aqua |
| 2 | Aqua |
| 04-07 | Land/Water |
| 0 | Shallow ocean |
| 1 | Land (Nothing else but land) |
| 2 | Ocean and lake shorelines |
| 3 | Shallow inland water |
| 4 | Ephemeral water |
| 5 | Deep inland water |
| 6 | Moderate or continental ocean |
| 7 | Deep ocean |
| 08-14 | Solar Zenith Angle at Local Solar Noon |
| 15 | QAFill |
| 255 | Fill Value |
| Bit Comb. | BRDF_Albedo_Band_Quality |
| 00-03 | Band 1 Quality |
| 0 | best quality, 75% or more with best full inversions |
| 1 | good quality, 75% or more with full inversions |
| 2 | Mixed, 50% or less full inversions and 25% or less fill values |
| 3 | All magnitude inversions or 50% or less fill values |
| 4 | 75% or more fill values |
| 04-07 | Band 2 Quality (see explanation for band 1) |
| 08-11 | Band 3 Quality (see explanation for band 1) |
| 12-15 | Band 4 Quality (see explanation for band 1) |
| 16-19 | Band 5 Quality (see explanation for band 1) |
| 20-23 | Band 6 Quality (see explanation for band 1) |
| 24-27 | Band 7 Quality (see explanation for band 1) |
| 28-30 | TBD |
| 31 | QAFill |
| 255 | Fill Value |
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