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[McIDAS #NJD-528776]: GINI Sounder Cloud Top Pressure image

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  • Subject: [McIDAS #NJD-528776]: GINI Sounder Cloud Top Pressure image
  • Date: Tue, 22 Apr 2008 15:53:58 -0600
Hi Kevin,

Sorry for not replying yesterday.  I have been searching the net for answers
to your questions...

re:
> I'm continuting to work with these CTP images.  I notice that there are
> a number of points whose brightness values are non-zero yet less than
> 76.

Yes, I noticed this as well.

> Thus, it appears I have to sacrifice precision by assuming that all
> values less than 77 are set to 950 mb.  Or, perhaps the range from the
> stretch table is wrong or out of date?

I don't know that hte stretch table values are out of date.

> Any ideas?

I am thinking that the last sentence from the following comment from the CIMSS 
page
on Cloud Top Pressure products may be relevant:

http://cimss.ssec.wisc.edu/goes/realtime/grtmain.html

  "Cloud top pressure (CTP) is derived from GOES-East and GOES-West Sounder 
radiance
   information routinely at hourly intervals. Calculations, using the CO2 
Absorption
   Technique, are made at each field of view. The image is then color enhanced 
to display
   50 hPa intervals where clouds have been identified. Due to the low-level 
atmospheric
   signal being dominated by surface emissions, this technique is less reliable 
for
   near surface clouds."

> Attached is a GIF showing pixel values near the northern edge of the
> grid domain @ the Washington/British Columbia border.

I understand; I was a bit puzzled by this as well.

> Thanks for any suggestions . . .

I will continue searching for more information on the CTP product; I will let 
you
know what, if anything, I find...

Cheers,

Tom
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Ticket Details
===================
Ticket ID: NJD-528776
Department: Support McIDAS
Priority: Normal
Status: Closed