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||The MODIS Vegetation Index product is retrieved accurately using a state of the art MODIS specific, quality driven, constrained view angle, maximum value composite method. For most cloud and snow free, low aerosol load pixels, the VI values are very reliable. The VI product is particularly dependent on coherent inter-band (blue, red and NIR) atmosphere correction and unstable values may be encountered over more extreme bright or dark surfaces. Over inland water bodies (rivers, lakes, etc...) surface reflectance inputs and VI values may not be stable and should be used with caution. Various field and flux tower validation campaigns indicate good agreement of VI values with land surface biophysical properties for most biomes, and cross sensor VI correlations (AVHRR, Landsat, SPOT, etc...) are very strong. Strong agreements are also found with the nadir-adjusted (NBAR) VI products. Users are advised to examine the per-pixel product quality to screen poor data before applying it to project-applications, science, and research. We will report any further findings with ongoing product assessments.
||Unstable VI values may occur over inland water bodies and snow/ice covered targets.
||Validated Stage 3