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2004102: vertical derivatives in GEMPAK?

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  • Subject: 2004102: vertical derivatives in GEMPAK?
  • Date: 25 Oct 2004 15:19:56 -0600
David,

LDF(s) will give you the layer difference where
you specify GLEVEL=level1:level2, and as
appropriate GVCORD=pres. This is the
equivalent of SUB(s1@level1,s2@level2).
If your vertical layer "delta-p" is reasonably small,
then you would be approaching D()/DP.

Steve Chiswell





On Mon, 2004-10-25 at 14:38, David Ovens wrote:
> Hello Gembuds,
> 
> I am trying to find out if anyone has written the veritcal equivalent
> of the DDX() and DDY() functions, namely, DDP().  A professor is
> interested in the tilting terms of the Petterson frontogenesis
> equation on constant pressure surfaces and we need the partial
> derivative of theta with respect to pressure, dthta/dp.  And, while
> we're at it, we may just go ahead and calculate the vertical
> deformation terms which require du/dp and dv/dp.
> 
> I've been hunting around in gemlib/df and gemlib/dv without finding
> anything helpful.  I can pretty much see how to do this myself, but am
> always interested in not re-inventing the wheel.
> 
> Thanks for any ideas.