Modis takes daily images at coarse resolution (500m?) that are then lumped into 16-day composites.
LandSAT, let's say 8, takes roughly bi-weekly images at 30m (100m resampled to 30), and those are then lumped into 32-day composites.
Clouds aside, would you generally expect the two for the same time period to match? In other words, if you aggregated the Landsat pixels by mean, ought you to get the same value of the corresponding Modis pixel?
Probably not, right? Could you explain why? Is it the 16 vs 32 days? The world changes in two weeks? Equipment differences? Resampling algorithms?
Are there any Modis-LandSAT pairs of data that actually would match quite closely?