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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
Pete, Thanks for the help. Actually, I already tried adding parens to the equation, including the variation you suggested, but the results are the same. Do you have a few lines of code that worked for you that you'd be willing to share? Or, do you recall whether there's any issue with netCDF auto-scaling the input data, or any units conversion that has to be included that's not in the documentation? Thanks... Art > From: "Pete Pokrandt" <poker@xxxxxxxxxxxx> > To: "ARTHUR AUGUST PERSON" <aap1@xxxxxxx>, "ldm-users" > <ldm-users@xxxxxxxxxxxxxxxx> > Sent: Friday, January 12, 2018 11:47:08 AM > Subject: Re: [ldm-users] Problem calculating GOES-16 brightness temperature > from > radiance > 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 -- 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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