NOAA-14 Update and January 23 Implementation Update

NOAA-14: Beginning on the morning of January 18, 2002, the AVHRR GAC
data changed so that most parameters reverted back to there normal
values after months of problems caused by high scan motor currents. As
of today all looks very good for the GAC. The HRPT data does seem to
demonstrate a slight problem causing earth locations to look off by
about a half pixel but not uniformly. Also, there appear to be numerous
pixel dropouts or bad data points throughout the data. We will continue
to monitor the data.

Level 1B update clarification:
We are not planning to zero out the orbit parameters in the header. You
should find that the parameters are still present. We have only
installed the capability so that if the need arises, we will do so
immediately and notify the user community.

When this change was implemented, we also implemented a change to
correct the computation of the satellite azimuth angle at nadir.
Problems had been reported for the AVHRR data where the angle was set
correctly to zero in the northern hemisphere and 180 in the southern
hemisphere, but occasionally the southern hemisphere would have zero set
instead of 180. This has been corrected.

* Emily D. Harrod
* Product Systems Branch
* Pre-Product Processing Group
* E/SP13, Federal Building #4, room 0318
* 5200 Auth Road
* Suitland, Maryland 20746-4304
* voice 301-457-5247
* fax 301-457-5199
* email