What do the time values in AIRS L1 and L2 data products represent?
The time values (TAI93: International Atomic Time 1993) are elapsed time in seconds since Jan 1, 1993, Coordinated Universal Time (UTC). For example, a time value of 410227204.00 corresponds to 12/31/2005 23:59:59.00 UTC. Note that a leap second was added at the end of 2005 (i.e. December 31, 2005). Therefore, TAI93 value of 410227206.00 (2 seconds after the above example) is 01/01/2006 00:00:00.00 UTC (not 01/01/2006 00:00:01.00 UTC) due to the leap second. Leap seconds are introduced on an irregular basis (see http://maia.usno.navy.mil/eo/leapsec.html for additional information on leap
seconds and ftp://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat for announcements
on the introduction of new leap seconds).
Why can't I get monthly AIRS data the day after the month is over?
AIRS monthly data require a complete set of the daily Level 3 global products, which in turn require a complete-as-possible set of of the Level 2 orbital products (given that orbital maneuvers, data dropouts, etc. affect the completeness of the data). It sometimes takes several days to complete the processing of the daily data ("closing out" the data processing stream) to the point where a monthly Level 3 data product can be created.
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Atmos Composition
