NOAA-16 AVHRR Visible Calibration Update, 11 February 2003 - Issued: 27 January 2003; 2000 UTC

3:20 PM
Subject: NOAA-16 AVHRR Visible Calibration Update, 11 February 2003 - Issued: 27 January 2003; 2000 UTC

Visible Calibration Monthly Updates

Date/Time(UTC) Message Issued:
27 January 2003; 2000 UTC

Satellite(s) Involved:

Instrument(s) Involved:

Product(s) Involved/Affected:
Channel 3A data users

Date/Time(UTC) of Initial Implementation:
11 February 2003/1700 UTC

Details/Specifics of Change:
The Office of Research and Applications instrument scientist, Dr. Xiangqian
Wu, has determined that the NOAA-16 AVHRR visible calibration coefficients
(slope and intercept) need to be updated. A monthly update procedure
was established for NOAA-J/14 such that updates were done on the second
Tuesday of each month. We would like to do the same for the NOAA-KLM
satellites beginning with NOAA-L/16. The first update is planned for the
second Tuesday in February ( February 11 ). Updates for following months
will occur on the second Tuesday. A notice containing the new values will
be issued.

Dr. Wu reports that the expected impact on the user community is as follows:

"For Channel 3A, currently all counts less than 71 results in negative
albedo. This error will be corrected such that all counts greater than 38
will results in positive albedo. This is the most significant change of this

Additionally for Channel 3A, albedo for counts less than 413 will increase,
typically less than 0.5% but up to 0.85% (at count=71, from 0% to 0.85%).
For counts between 414 and 541, the albedo will decrease slightly,
typically less than 0.2% but up to 0.48% (at count=499, from 12.09% to
11.61%). For counts greater than 542, the albedo will increase, up to 4.76%
at count=959 (from 95.17% to 99.93%)."

Dr. Wu has provided a more detailed explanation of why these updates are
needed. This information has been added to the NOAA KLM Users' Guide in
Appendix D.2. Please click on the following link to go directly to that
section of the users' guide. The text begins following Table D.2-6.

Operations estimates that a two week notice to the user community for this
initial update is sufficient. Please contact us as soon as possible if this
is not the case. Test data will be made available for the February 11
update. No test data will be provided for other updates. CEMSCS users will
find test level 1B data beginning with the extent, "P1S" for 1B* data and
"P1B" for 1B data. Other level 1B users will find test data on the
anonymous ftp site - under the subdirectory

Following are the new coefficients:


(Low) 0.0287 0.0262
(Low) -2.043 -1.01
(high) 0.1806 0.1920
(high) -78.03 -84.2

Contact Person(s) Name/Email/Phone Number for Questions: ext. 117 or ext. 124

Web site(s) that contain other relevant information (where applicable): - NOAASIS Satellite
Instrument Calibration web site - SOCC morning reports - History of level 1B
notices - All user notices

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