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[McIDAS #CLT-967906]: update and some questions
- Subject: [McIDAS #CLT-967906]: update and some questions
- Date: Tue, 14 Aug 2018 14:15:42 -0600
Hi Ioan,
re:
> long time no hear...
Yes indeed!
re:
> how are you doing....? have you been on holiday? We had a weird summer in
> Europe this year,
I'm doing well, thanks. I did have a holiday in England in July, but I've
been back for almost a month now.
re:
> the June and July were quite cold..... but now the temps are as they
> should.
It has been very warm here, and WAY too dry!
re:
> As for me no real holiday this year ...I was working:)))
I know the feeling :-(
re:
> I have managed to port pyadde and pyarea to python 3 (async) and built an
> integrated (multisource) data downloader which should ensure we do not
> miss any data in case some sources do not work.
This sounds very interesting and useful!
re:
> I'll send you the updated libs (pyadde pyarea) once I package them.
Thanks.
re:
> I want to discuss shortly two things:
>
> A. GOES16
> I believe I have already asked you this question but I am going to do it
> again in case you got some update on the matter in the meantime.
>
> Right now we have 3 sources of GOES16 data
>
> 1. real time
> https://www.googleapis.com/storage/v1/b/gcp-public-data-goes-16/o NetCDF
> 2. lead.unidata.ucar.edu McIDAS AREA
> 3. CLASS NetCDF
Excellent, I always like redundancy.
You can add to your list:
4. atm.ucar.edu - McIDAS AREA (via ADDE)
5. thredds-test.unidata.ucar.edu netCDF (via the TDS)
Coming up sometime reasonably soon will be:
6. adde.ucar.edu - McIDAS AREA (via ADDE)
7. thredds.ucar.edu - netCDF (via the TDS)
re:
> I was wondering if you got any updates/news from SSEC on the ABI McIDASX
> server because some calibration parameters are still missing from the AREA
> files.
I don't recall you asking this previously, so please forgive the questions:
- which calibration parameters are missing from the calibration block in a
McIDAS AREA file?
I just looked at the SSEC-written server code for the GRB-delivered ABI imagery,
and I think that it reads and stores all of the calibration information that
is available in the netCDF-4 files that are created by the CSPP GEO software
that we are running on our GOES-16 downlink.
Here are what I deem to be calibration-related values in the GRB netCDF-4 files
(please correct me when I am wrong/missing something!):
short Rad(y, x) ;
Rad:_FillValue = 1023s ;
Rad:long_name = "ABI L1b Radiances" ;
Rad:standard_name = "toa_outgoing_radiance_per_unit_wavelength"
;
Rad:_Unsigned = "true" ;
Rad:sensor_band_bit_depth = 10b ;
Rad:valid_range = 0s, 1022s ;
Rad:scale_factor = 0.8121064f ;
Rad:add_offset = -25.93665f ;
Rad:units = "W m-2 sr-1 um-1" ;
Rad:resolution = "y: 0.000028 rad x: 0.000028 rad" ;
Rad:coordinates = "band_id band_wavelength t y x" ;
Rad:grid_mapping = "goes_imager_projection" ;
Rad:cell_methods = "t: point area: point" ;
Rad:ancillary_variables = "DQF" ;
The operative calibration values from this list should be: scale_factor and
add_offset.
float band_wavelength(band) ;
band_wavelength:long_name = "ABI band central wavelength" ;
band_wavelength:standard_name =
"sensor_band_central_radiation_wavelength" ;
band_wavelength:units = "um" ;
The operative calibration value here is the band_wavelength itself.
float kappa0 ;
kappa0:_FillValue = -999.f ;
kappa0:long_name = "Inverse of the incoming top of atmosphere
radiance at current earth-sun distance (PI d2 esun-1)-1, where d is the ratio
of instantaneous Earth-Sun distance divided by the mean Earth-Sun distance,
esun is the bandpass-weighted solar irradiance and PI is a standard constant
used to convert ABI L1b radiance to reflectance" ;
kappa0:units = "(W m-2 um-1)-1" ;
kappa0:coordinates = "band_id band_wavelength t" ;
kappa0:cell_methods = "t: mean" ;
float planck_fk1 ;
planck_fk1:_FillValue = -999.f ;
planck_fk1:long_name = "wavenumber-dependent coefficient (2 h
c2/ nu3) used in the ABI emissive band monochromatic brightness temperature
computation, where nu =central wavenumber and h and c are standard constants" ;
planck_fk1:units = "W m-1" ;
planck_fk1:coordinates = "band_id band_wavelength" ;
float planck_fk2 ;
planck_fk2:_FillValue = -999.f ;
planck_fk2:long_name = "wavenumber-dependent coefficient (h c
nu/b) used in the ABI emissive band monochromatic brightness temperature
computation, where nu = central wavenumber and h, c, and b are standard
constants" ;
planck_fk2:units = "K" ;
planck_fk2:coordinates = "band_id band_wavelength" ;
float planck_bc1 ;
planck_bc1:_FillValue = -999.f ;
planck_bc1:long_name = "spectral bandpass correction offset for
brightness temperature (B(nu) - bc_1)/bc_2 where B()=planck_function() and
nu=wavenumber" ;
planck_bc1:units = "K" ;
planck_bc1:coordinates = "band_id band_wavelength" ;
float planck_bc2 ;
planck_bc2:_FillValue = -999.f ;
planck_bc2:long_name = "spectral bandpass correction scale
factor for brightness temperature (B(nu) - bc_1)/bc_2 where
B()=planck_function() and nu=wavenumber" ;
planck_bc2:units = "1" ;
planck_bc2:coordinates = "band_id band_wavelength" ;
All of these values are needed for calibration.
The McIDAS-X server code for GRB ABI imagery contains:
memcpy( (void *)&cal_block[0], (void *)"ABIN",4);
cal_block[j] = image_band;
cal_block[j+1] = (int)(WaveLength[image_band-1] *10000000.0);
cal_block[j+2] = (int)(VAR_scale[image_band-1] *10000000.0);
cal_block[j+3] = (int)(VAR_offset[image_band-1] *10000000.0);
cal_block[j+4] = 0;
cal_block[j+5] = 0;
cal_block[j+6] = 0;
cal_block[j+7] = 0;
cal_block[j+8] = 0;
cal_block[j+9] = 0;
cal_block[j+10] = 0;
cal_block[j+11] = (int)(kappa[image_band-1] *10000000.0);
cal_block[j+12] = 0;
cal_block[j+13] = (int)(planckFK1[image_band-1] *10000.0);
cal_block[j+14] = (int)(planckFK2[image_band-1] *10000.0);
cal_block[j+15] = (int)(planckBC1[image_band-1] *10000000.0);
cal_block[j+16] = (int)(planckBC2[image_band-1] *10000000.0);
cal_block[j+17] = VAR_FillValue[image_band-1];
The association between the values I listed from the netCDF-4 files
are:
netCDF-4 AREA calibration block
----------------+-----------------------
band_wavelength Wavelength
scale_factor VAR_scale
add_offset VAR_offset
kappa0 kappa
planck_fk1 planckFK1
planck_fk2 planckFK2
planck_bc1 planckBC1
planck_bc2 planckBC2
re:
> I have ways to deal with it but It would be so nice if the AREA
> files that come from lead would be one to one with the NetCDF files.
Which calibration value(s) are missing?
re:
> B: the rebuild of GOES archives using pygvar
>
> I have made some nice progress with this task. However my boss, is not 100%
> happy because the GOES image are of course a little wobbly (+- 1 px) mostly
> the VIS channel.
I assume that you mean the GOES GVAR images. I see that the animated GIFs
that you attached were all from GOES-8...
re:
> I am attaching 3 files so you can have a look.
> My question is:...do you know anybody /somebody who tried to correct these
> kind of issues with GOES satellites
I know that a LOT of work was done to correct the inter-band registration
for IR channels for GOES GVAR satellites. There are more than one published
papers on what the problem was and how it can be corrected.
I feel certain that there has been a LOT of work done on correcting the
registration for older GOES satellites (e.g., GOES-8), but I can't give
you any references, sorry.
re:
> pygvar does a good enough job in my opinion but that one pixel gives my
> boss trouble.:))).
I have observed registration problems with GOES GVAR AND GRB images. The
only good news is that I see far fewer in the GRB images than I saw in
GVAR images.
re:
> All the best
You too!
Cheers,
Tom
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Ticket Details
===================
Ticket ID: CLT-967906
Department: Support McIDAS
Priority: Normal
Status: Closed
===================
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