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19990220: Sounder IR channel temperature calibrations

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  • Subject: 19990220: Sounder IR channel temperature calibrations
  • Date: Sun, 21 Feb 1999 15:47:11 -0700
>From: Anthony James Wimmers <address@hidden>
>Organization: UVa
>Keywords: 199902202045.NAA04118 McIDAS-X

Tony,

>I'm working on some sounder areafiles. I notice that when I display images
>from the ir bands 1,2 or 3 (but not limited to them) the temperatures are in
>the right ballpark, but they become warmer as you go north. I'm pretty sure
>this problem stems from the calibration type.

Why are you convinced that this is the problem?  What are the brightnesses
doing as you move north?  Did you apply a stretch to the image when you
loaded it?

>So I have two questions:
>
>o How do I fix this so that the temperatures display properly?

If you loaded the image with a stretch table, this could be your problem.

>o Is it in the right format to do IMGOPER on it where UNIT=TEMP, or will I
>  have to change calibrations?

I am not sure I understand your comment about changing calibration.
The relationship between the sensor counts and derived units (e.g.
temperature) should taken care of in the calibration module for the
data.  It seems to me that the only thing you can change is the stretch
that you load the image with, but, perhaps I am missing something.
Can you give me ADDE access to the image(s) in question (dataset and group
names)?

>Much obliged,

Talk to you tomorrow.

>Tony Wimmers
>University of Virginia

Tom Yoksas

>From address@hidden  Mon Feb 22 09:39:32 1999

re: changing calibration
>That's what I thought too. After I read your message, I set out to prepare an 
>example, and in the course of things I found that with bands 1 and 2 of the 
>sounder, the temperatures are normally supposed to increase as you go north.
>So everything's fine.

>Thanks,

>Tony Wimmers
>University of Virginia