Re: [ldm-users] Problem calculating GOES-16 brightness temperature from radiance

• To: Arthur A Person <aap1@xxxxxxx>, "ldm-users@xxxxxxxxxxxxxxxx" <ldm-users@xxxxxxxxxxxxxxxx>
• Subject: Re: [ldm-users] Problem calculating GOES-16 brightness temperature from radiance
• From: Pete Pokrandt <poker@xxxxxxxxxxxx>
• Date: Fri, 12 Jan 2018 16:47:08 +0000
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Art,


I think it may be a parenthesis/order of operations issue. I seem to recall 
having this same issue when I first started working with the GRB data.

Try this:


bt = ( planck_fk2 / ( np.log((planck_fk1 / rad) + 1 )) - planck_bc1) / 
planck_bc2


Pete




________________________________
From: ldm-users-bounces@xxxxxxxxxxxxxxxx <ldm-users-bounces@xxxxxxxxxxxxxxxx> 
on behalf of Arthur A Person <aap1@xxxxxxx>
Sent: Friday, January 12, 2018 7:43 AM
To: ldm-users@xxxxxxxxxxxxxxxx
Subject: [ldm-users] Problem calculating GOES-16 brightness temperature from 
radiance

Hi...

I'm trying to calculate brightness temperature from radiance for GOES-16 IR 
channel 7 using rebroadcast data
but my values compared to McIDAS imagery are coming out 15 to 20 degrees C too 
warm.  I'm using the following
values and code:

Test imagery: 
OR_ABI-L1b-RadC-M3C07_G16_s20180112232223_e20180112235008_c20180112235045.nc

rad (radiance) is read in from and auto-scaled by netCDF,
planck_fk1:  202263.0
planck_fk2:  3698.18994140625
planck_bc1:  0.4336099922657013
planck_bc2:  0.9993900060653687

bt = ( planck_fk2 / np.log( (planck_fk1/rad)+1 ) - planck_bc1 ) / planck_bc2
bt = bt - 273.15

Can anyone tell me if I'm missing a step or spot a dumb mistake?

Thanks...       Art

--
Arthur A. Person
Assistant Research Professor, System Administrator
Penn State Department of Meteorology and Atmospheric Science
email:  aap1@xxxxxxx, phone:  814-863-1563

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    • From: Arthur A Person