AIRS

Frequently Asked Questions

Q. I'm using the 1 deg gridded daily LEVEL 3 AIRS product. Is there a way
for me to simply approximate the average UTC time?

A. There is no way to get an average UTC for the data within a grid box
except for those grid boxes where the swath fields do not overlap.

If no overlap of swaths, the data can only come from one orbit.
Recall that Aqua is sun-synchronous with an orbital period of 90
minutes and a northbound crossing local time of 1:30 PM standard.
From those facts you can determine the approximate UTC as a function
of latitude and longitude for latitudes within the low-latitude band
where swaths from neighboring orbits do not overlap. Of course, you
must treat the ascending and descending data separately.

Once there is overlap, you cannot know the orbit which contributed one
or more of the observation. that have been averaged. Effectively a
time window opens wider with increasingly high latitude, becoming 24
hours wide (in the daily L3 product) near the poles.

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