published 7 Jan 2013 notified users that AIRS Level 1B radiances were reprocessed for the period from 21 Jan 2012 through 2 Jan 2013, replacing the V5.0.0 AIRS L1B product with V5.0.21 AIRS L1B product for that time period and reflecting updated Calibration Properties and Channel Properties. Although the AIRS Level 1B algorithm is unchanged, the updated calibration and channel properties files result in small changes in radiances. AIRS L1B products from 21 Jan 2012 through the current date are V5.0.21.
Some properties of channels change slowly with time or discontinuously whenever the instrument is warmed by a spacecraft safety shutdown or in a defrost cycle. To account for this, a new calibration epoch is initiated. In addition, epochs are started about every 6 months to provide finer-grained temporal information on the health of each detector. Calibration tests are performed for each epoch and new channel properties and calibration properties files are created.
Please refer to the document V5 L1B_QA_QuickStart.pdf
. Tables on pages 5 and 6 list the calibration and channel properties files used in V5 and V6 Level 1B and Level 2 processing. The dates in the file names indicate the first date at which a properties file is used. The version number of the Channel Properties files have changed from V5.9.1 to V5.9.3. This reflects the software build number of the code that creates these files, but the data within them are identical except for one change. The only change from the old set reflected in the new set is that the AB_State of channel number 2067 was changed from "0" to "3" for epochs with start dates 2009-01-01 through 2011-01-01.