Based on the response received, we believe that we can go forward with our
plans to update the planck constants and to add the ability to switch the
orbit parameters in the header on and off. We plan to put the changes into
operation on January 23, 2002. We will continue to provide the orbit
parameters in the header and hence this should be a "no impact" change. We
have provided test results below for you to compare to what you are seeing.
Test data will continually be available until the actual implementation
date. If you have any questions or problems, please contact me.
Thank you and Happy New Year!!!
Emily
Reports from instrument scientists and users on the observed impact of the
change in test data provided.
HIRS
Dr. Changyong Cao of Office of Research and Applications reports that
NOAA-15 and NOAA-16 the max difference observed in HIRS is on the order of
0.003 mW/m2-sr-cm-1.
AVHRR
Dr. Jerry Sullivan, Office of Research and Applications reports the
following for AVHRR:
For NOAA-16, comparisons were done using the data sets
NSS.GHRR.NL.D01340.S1047.E1231.B0622021.GC.OPS
P1B.GHRR.NL.D01340.S1047.E1231.B0622021.GC
and for NOAA-15, the data sets
GHRR.NK.D01323.S1126.E1310.B1828990.WI.OPS
GHRR.NK.D01323.S1126.E1310.B1828990.WI
These GAC orbits contain 5,000,000 Earthscene pixels.
For AVHRR channels 4 and 5, for both NOAA-16 and NOAA-15, the RMS difference
between equivalent brightness temperatures generated from the old-Planck and
new-Planck datasets was 0.001K .
For AVHRR channel 3B radiances/temperatures computed by using two different
values for the Planck constants. Radiance was converted into equivalent
blackbody temperature to make the comparison easier. Comparisons were
broken down into three temperature ranges: >275K (SST range), 240-275 range,
and the cold range from 200-240K. The accuracy of channel 3B temperatures
below 240K is always somewhat suspect because on average there is a jump of
2.5K for the minimum count change of one count.
There were 5,000,000 pixels in the NOAA-15 datasets but only 2,500,000 in
the NOAA-16 because channel 3A was on part of the time. The table below
shows the channel 3B RMS temperature difference between datasets using the
old and new Planck constant values.
> 275K 240-275K 200-240K
NOAA-16 0.022K 0.106K 0.434K
NOAA-15 0.019K 0.095K 0.400K
AMSU-A and AMSU-B
Dr. Clement Chouinard of Data Assimilation and Satellite Meteorology
Division; Dorval P.Q. CANADA (results of test done on one orbit) reports:
Number of AMSU-A data 347,400 ( 23,160 pixels * 15 channels )
3585 ( 1.32% ) larger than .01 degres
318328 ( 91.63% ) identical
12149 ( 3.50% ) smaller than 0.01 degres
7084 ( 2.04% ) smaller than 0.02 degres
5525 ( 1.59% ) smaller than 0.03 degres
241 ( 0.07% ) smaller than 0.04 degres
226 ( 0.07% ) smaller than 0.05 degres
160 ( 0.05% ) smaller than 0.06 degres
100 ( 0.03% ) smaller than 0.07 degres
2 ( 0.00% ) smaller than 0.08 degres
Number of AMSU-B 1,042,200 ( 208,530 pixels * 5 channels )
3161 ( 0.30% ) larger than.02 degres
82700 ( 7.93% ) larger than .01 degres
765948 ( 73.46% ) identical
167251 ( 16.04% ) smaller than 0.01 degres
16911 ( 1.62% ) smaller than 0.02 degres
4778 ( 0.46% ) smaller than 0.03 degres
1450 ( 0.14% ) smaller than 0.04 degres
303 ( 0.03% ) smaller than 0.05 degres
148 ( 0.01% ) smaller than 0.06 degres
--
*******************************************
*
* Emily D. Harrod
* NOAA/NESDIS/OSDPD/IPD
* Product Systems Branch
* Pre-Product Processing Group
* E/SP13, Federal Building #4, room 0318
* 5200 Auth Road
* Suitland, Maryland 20746-4304
* USA
* voice 301-457-5247
* fax 301-457-5199
* email Emily.Harrod@noaa.gov
*
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