MODIS gain correction

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wvkim
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MODIS gain correction

by wvkim » Mon Aug 14, 2023 10:47 pm America/New_York

I have been informed that the MODIS Aqua and Terra gain correction factors have been integrated into the SeaDAS software. Could you please confirm if this implementation is accurate?
If the gain correction factors are indeed available in SeaDAS, could you kindly guide me on how to obtain the correction factors for both Aqua and Terra?

Thanks

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OB ODPS - towens
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Re: MODIS gain correction

by OB ODPS - towens » Tue Aug 15, 2023 12:41 pm America/New_York

If you look in your seadas_install_dir/ under ocssw/share/modis/aqua/
There is a file msl12_defaults.par

you can find the gain setting there:
gain=[0.97581,0.98510,1.00373,0.98908,0.99648,0.99128,0.98844,0.99868,1.00551,1.00462,0.99858,0.98935,1.0,1.0,1.0,1.0]

ocssw/share/modis/terra
gain=[0.99444,0.99119,1.00025,1.01352,1.00287,0.99449,1.00317,1.00877,0.99500,1.00370,0.99567,0.97259,1.0,1.0,1.0,1.0]

Tommy

wvkim
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Re: MODIS gain correction

by wvkim » Tue Aug 15, 2023 1:46 pm America/New_York

Unfortunately, I couldn't find the ocssw/share/modis/aqua/ directory.
Below is the list of files and directory in my seadas installed directory
"THIRDPARTY_LICENSES.txt, etc, platform, Uninstaller, ide, seadas-toolbox, VERSION.txt, jdk-11.0.19+7-jre, snap,bin, optical-toolbox"

Also, it seems like both aqua and terra has 16 gain factors. Could you please let me know the meaning of each factor?
Is it a gain factor of each year?

OB ODPS - towens
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Re: MODIS gain correction

by OB ODPS - towens » Thu Aug 17, 2023 10:17 am America/New_York

Each value corresponds to the correction for a particular band (nm):

Code: Select all

#     412    443    469    488    531    547    555    645    667    678    748    859    869  1240 1640 2130
gain=[0.97581,0.98510,1.00373,0.98908,0.99648,0.99128,0.98844,0.99868,1.00551,1.00462,0.99858,0.98935,1.0,1.0,1.0,1.0]
I'll defer to one of our SeaDAS experts regarding the location of /share

OB SeaDAS - xuanyang02
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Re: MODIS gain correction

by OB SeaDAS - xuanyang02 » Thu Aug 17, 2023 11:01 am America/New_York

It seems that you don't have ocssw (SeaDAS Science Processors) installed in the directory you installed seadas.
You need to install ocssw modis aqua to have the ocssw/share/modis/aqua/ directory and its content. Here is the link on how to install ocssw -https://seadas.gsfc.nasa.gov/downloads/
wvkim wrote: Tue Aug 15, 2023 1:46 pm America/New_York Unfortunately, I couldn't find the ocssw/share/modis/aqua/ directory.
Below is the list of files and directory in my seadas installed directory
"THIRDPARTY_LICENSES.txt, etc, platform, Uninstaller, ide, seadas-toolbox, VERSION.txt, jdk-11.0.19+7-jre, snap,bin, optical-toolbox"

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