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[McIDAS #JKQ-991036]: Re: MCIDAS Grayscale Question



Hi Rod,

re:
> My question to the professor:

> I asked my professor if I can find out on McIDAS-X by a command of some
> sort of information on what the elevation is for the effective
> radius/visible satellite images taken from?
>
> He stated: By elevation, do you mean cloud top height or pressure? If so,
> you can get a rough estimate by comparing the cloud top temperature with
> representative temperature sounding. NESDIS and CIMSS produce cloud top
> height and pressure products computed using all the IR bands.
> 
> Can you understand what he is saying?

Yes.  What he is saying is the following:

- if you have an IR image (not VIS), then the pixel values are temperatures
  (thermal emission).  If one assumes that the pixel under the mouse cursor
  represents the top of the cloud (this is not a bad assumption; it is
  almost correct), then you can use McIDAS to interrogate the image for
  its brightness AND temperature [K] values.  Once you have the temperature(s),
  you can compare it(them) with a sounding taken near (in space and time) the
  pixel and read the representative height/pressure from the sounding.

  To do this, you will need soundings from the radiosonde stations
  in/near your area of study taken as close as possible in time to
  the time of your study.  It would also be best if you had the
  thermal IR images (10.7 um) for the times of interest.  The Effective
  Radius images you have are a combination of the thermal (10.7 um)
  and short wave (3.9 um) imagery.  I have a feeling that these would
  not be as good as the thermal IR images for the estimation of
  cloud height.


Cheers,

Tom
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Ticket Details
===================
Ticket ID: JKQ-991036
Department: Support McIDAS
Priority: Normal
Status: Closed


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