Level 1B Updates for December 12,

The Information Processing Division has announced that no changes will be
made to operational systems from December 15, 2000 through January 2,
2001. On December 12, the Pre-Product Processing group is planning to make
several changes to the level 1B process before the freeze begins. These
changes should have no impact to the user community. The changes will make
it possible for us to correct clock drift errors in the NOAA-16 AVHRR data
and will correct effects of moon glint in the NOAA-15 AMSU-B data. A
summary of the changes is provided below. Parallel testing will be
conducted throughout the week of December 4th. Test data for NOAA-14,
NOAA-15 (AIP only), and NOAA-16 will be available. Level 1B test data will
be available on the anonymous ftp server ( under the
subdirectory pub/test1b/dec00. Level 1B* data will be available under the
P1S and P1B names for the appropriate satellite. Please contact us if you
need additional test data.

< The KLM level 1B preprocessing software will be updated
to include AMSU-B moon glint anomaly corrections. Changes to the
level 1B format are not required. The user will find that
previously unusable data will now be processed as normal. User
impact - Increased data quality.

< The NOAA-16 Calibration file will be updated to allow moon
glint corrections for High Resolution Infrared Radiation Sounder
(HIRS) data on that spacecraft. User impact - Increased data

< Both the KLM and A-J level 1B preprocessing systems will
be updated to allow scan geometry parameters to be changed to
user supplied parameters. This will give us the ability to adjust
the scan geometry differently for different satellites. User
impact - improved earth location data due to use of double
precision variables. New MSU scan angle +/-47.3685 degrees
(difference in latitude of 0.01 degrees, longitude 0.03 degrees);
AVHRR new stepping angle 0.05407226563 degrees for all satellites
except NOAA-16 which will be 0.053955078 degrees; AMSU-A - maximum
difference in latitude of 0.005 and longitude of 0.0001; AMSU-B -
maximum difference in latitude of 0.0001 and longitude of 0.0001.

< The clock drift corrections for the NOAA-16 spacecraft
will be turned on to correct the along track error. User impact
- improved earth location data removing clock error of about 650
milliseconds (about 4 kilometers).

Emily D. Harrod
E/SP13 Room 0308 FB#4
5200 Auth Road
Suitland, Md. 20746-4304
(301)-457-5247 phone