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[McIDAS #LFB-979507]: McIDAS - GOES-12 imager calibration help



Hi Gautam,

re:
> Thank you for forwarding my question to other ppl.

No worries.  We always bounce McIDAS questions back to SSEC when
we can't answer them.

> I did determine
> the images I have on my local server were 'RAW' images.
> 
> IMGLIST GOES12/VIS.3 FORM=EXP
> Image file directory listing for:GOES12/VIS
> Pos Satellite/         Date       Time      Center      Res (km)
> Image_Size
> sensor                                 Lat  Lon    Lat   Lon
> --- -------------  ------------  --------  ---- ----  ----- -----
> ------------
> 3  G-12 IMG      12 APR 06102  21:32:00
> Band: 1   0.65 um Visible - Cloud Cover
> 480 x  640
> proj:    0 created: 2006102 214420  memo: RT GVAR
> type:GVAR     cal type:RAW
> offsets:  data=    3328 navigation=  256 calibration= 2816
> auxillary=    0
> doc length:   0   cal length:   0   lev length:   0 PREFIX=   0
> valcod:          0 zcor:  0 avg-smp: N
> start yyddd: 2006102  start time:213144  start scan:  355
> lcor: 2837  ecor:  9277  bytes per pixel: 2  ss: 78
> Resolution Factors (base=1):   Line=    1.0   Element=    1.0
> IMGLIST: done

Very good.  Unfortunately, it takes a bit more to get images that have
the necessary information.  Here is the information I received from
SSEC:

  The detector information is in the documentation section of the AREA
  files, so if they used IMGCOPY, they had to use DOC=YES.  The XRD
  command GVARINFO gives the detector information - look for the value lidet.

  There are 2 detectors for the IR channels. The same detector number
  applies to line of either single- or multi-band IR. A note for visible
  data, we use an average of the 8 detector calibration coefficients. Why?
  Because the visible sensors are not continually calibrated and their
  response degrades over time. There are some empirical coefficients to
  correct for this, based on the length of time the sensor has been in
  operation.

The XRD (X Research and Development) application that is referred to
is included in the Unidata McIDAS-X distribution.  It is not, however,
built/installed by default.  After you have completely built McIDAS-X,
you will need to create the GVARINFO executable and help file as
follows:

<as 'mcidas'>
cd ~mcidas/mcidas2005/src
make gvarinfo.k gvarinfo.hlp
ln gvarinfo.k ~/bin
ln gvarinfo.hlp ~/help

You then run 'HELP GVARINFO' from the McIDAS Text and Command window
(or run 'help.k GVARINFO' from the Unix command prompt while logged
in as 'mcidas' or any other user whose Unix environment has been
configured to run McIDAS).

> Also, of the various dataset available (ALL, CONUS, FD, NH, OTHER,
> SH) for GOES-East/West, is the difference between them is only the
> various map re-projection ?

The projections are all the same (assuming that you are getting the
images from datasets like PUB EAST or WEST from UNIDATA2.SSEC.WISC.EDU.
The difference is the region that the sector covers; the projection is
the same in all.

Question: where are you getting your images from?

> If so, which one of them is the one that
> the satellite sees (level_0) ?

All RAW images reflect what the satellite sees.

> In the operational configuration for GOES-12, the GVAR scan output
> for visible band is such Detector 5 is northmost, followed by 6,7 8,
> 1, 2, 3 and 4. Thus I am thinking if the level_0 data is known then
> the arrangement of the detectors  might be know like this (One whole
> line corresponds to one detector and not as I earlier thought)
> 
> line:  Dec_5_ele_1 Dec_5_ele_2 ......
> line:  Dec_6_ele_1 Dec_6_ele_2 ......
> line:  Dec_7_ele_1 Dec_7_ele_2 ......
> line:  Dec_8_ele_1 Dec_8_ele_2 ......
> line:  Dec_1_ele_1 Dec_1_ele_2 ......
> line:  Dec_2_ele_1 Dec_2_ele_2 ......
> line:  Dec_3_ele_1 Dec_3_ele_2 ......
> line:  Dec_4_ele_1 Dec_4_ele_2 ......
> 
> I might be completely wrong about it. Thank you for your help.

As was pointed out in the message sent by SSEC to me regarding your
inquiry, the detector-specific information is contained in the
document part of the image.  If you are creating the AREA files
using IMGCOPY from a remote server that has the RAW data, you
must include the DOC=YES keyword sequence when creating the local
image (and you need to create a local image to use GVARINFO since
this application does not use ADDE).

Cheers,

Tom
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Ticket Details
===================
Ticket ID: LFB-979507
Department: Support McIDAS
Priority: Normal
Status: Closed


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