Definition of Day for Collection 6: These pages illustrate the C6 methodology for daily Level-3 aggregation.
Previously, we have simply aggregated all measurements taken during a 24hr Greenwich day that consists of
288 5-minute MODIS granules starting at 00:00 GMT. Because orbits do not repeat on a daily cycle,
consecutive days start with the instrument at very different latitudes on the globe.
This makes for data gaps and crude overlaps of early morning measurements with late day measurements.
In Aqua Collecion 6, we first subtract the early (00:00 to 03:00 GMT) measurements just to the East of the Dateline (equator day)
and just to the East of the Greenwich meridian (equator night). Please exercise the Subtract button.
Then we add early measurements from the following day to the same longitude zones to complete full and contiguous coverage.
This gives orbit-to-orbit continuity except for seams at the Dateline (daylight orbits) and Greenwich meridian (night orbits).
Observe how day and night measurements behave correspondingly when the globe is rotated.
For Terra Colleciont 6, the exercise is very similar, but with some end-of-day measurements excluded and
prior day end-of-day measurements included. All excluded measurements will contribute to the next day.
The specific rule set for each mission is shown in the table below and is the basis for our C6 aggregation algorithm.