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Pete, By default, netCDF4-python applies the scale and offset when you read in the data. This can be disabled by calling `set_auto_scale()` on individual variables or on the Dataset itself. Ryan On Sat, Jan 13, 2018 at 7:03 PM, Pete Pokrandt <poker@xxxxxxxxxxxx> wrote: > Forgot to cc to the list. > > Here's a commented version of the script that I'm currently using to plot > ABI channel 13 (clear channel IR window) but the calculation for BT should > work for any of the channels 7-16. > > I am using just the radiance values read in from the netcdf files, without > applying any scale/offset to them. Perhaps the netcdf4 read does that for > us? I am reading the scale and offset info in for reference, and printing > them out, but I am not using them in my calculations at all. > > If for some reason, the attachment doesn't come through, you can get the > file at > > http://sysadm.aos.wisc.edu/~poker/goes16_GRB_fulldisk_IR13_ircm.py > > Hope this helps, > Pete > > > > <http://www.weather.com/tv/shows/wx-geeks/video/the-incredible-shrinking-cold-pool> > -- > Pete Pokrandt - Systems Programmer > UW-Madison Dept of Atmospheric and Oceanic Sciences > 608-262-3086 <(608)%20262-3086> - poker@xxxxxxxxxxxx > > > ------------------------------ > *From:* Arthur A Person <aap1@xxxxxxx> > *Sent:* Saturday, January 13, 2018 9:04 AM > *To:* Pete Pokrandt > *Cc:* ldm-users > > *Subject:* Re: [ldm-users] Problem calculating GOES-16 brightness > temperature from radiance > > 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@unidata. > ucar.edu> 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 <(814)%20863-1563> > > > -- > Arthur A. Person > Assistant Research Professor, System Administrator > Penn State Department of Meteorology and Atmospheric Science > email: aap1@xxxxxxx, phone: 814-863-1563 <(814)%20863-1563> > > _______________________________________________ > NOTE: All exchanges posted to Unidata maintained email lists are > recorded in the Unidata inquiry tracking system and made publicly > available through the web. Users who post to any of the lists we > maintain are reminded to remove any personal information that they > do not want to be made public. > > > ldm-users mailing list > ldm-users@xxxxxxxxxxxxxxxx > For list information or to unsubscribe, visit: > http://www.unidata.ucar.edu/mailing_lists/ > -- Ryan May, Ph.D. Software Engineer UCAR/Unidata Boulder, CO
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