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Landsat Surface Reflectance Quality Assessment

Landsat Surface Reflectance products include Quality Assessment (QA) bands to identify the pixels that exhibit adverse instrument, atmospheric, or surficial conditions. Used effectively, QA information improves the integrity of science investigations by indicating which pixels might be affected by instrument artifacts or subject to cloud contamination. 

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For example, NDVI calculated over pixels containing clouds will show anomalous values. If such pixels were included in a phenology study, the results would likely not show the true characteristics of seasonal vegetation growth. Cloud contaminated pixels will lower NDVI values, and measures like the timing of ‘green up’ or peak maturity would appear later than they actually occurred. A worse consequence would be the reported reduction of vegetation growth would be taken as an indicator of environmental change, potentially prompting unnecessary land management policies or practices.

Landsat 4-5 Thematic Mapper (TM) and Landsat 7 Enhanced Thematic Mapper Plus (ETM+) Surface Reflectance products are generated from the Landsat Ecosystem Disturbance Adaptive Processing System (LEDAPS)

Landsat 8 and Landsat 9 Surface Reflectance products are generated from the Land Surface Reflectance Code (LaSRC).