Aggregation is carried out independently for each band.
Aggregation is done at two stages, first at native resolution and then at 1km resolution. Observations are weighted by observation coverage to get the aggregated value. Note that the algorithm does not remove bow-tie. Since the algorithm drops out the bad observations, the aggregated values do not get biased by the bad observations. Such aggregated observations that fall within a 1km grid cell are then averaged to produce 1km aggregated reflectance value.