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Re: Potential vorticity
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  * To: {GRADSUSR@LIST.CINECA.IT} 
  * Subject: Re: Potential vorticity 
  * From: "Goodson,Ron [Edm]" <{Ron.Goodson@EC.GC.CA}> 
  * Date: Mon, 11 Jun 2001 09:34:40 -0600 
  * Comments: To: "caruso@SOEST.HAWAII.EDU" <caruso@SOEST.HAWAII.EDU> 
  * Reply-To: {GRADSUSR@LIST.CINECA.IT} 
  * Sender: {GRADSUSR@LIST.CINECA.IT} 

------------------------------------

Here is a not-much-tested-at-all script.  It gives numbers that are close
but probably not exact.  Use with caution... and maybe let me know if the
thing works.

You will have to change the variable names to match your u,v,temperature.
Also note this is hard-coded for pressure layer of 100 mb.

Ron Goodson


--------- start script -------------------

'define vort = hcurl(ugrdprs,vgrdprs) + ( 2 * 7.292e-5 * sin(lat * 3.1415
/180))'
'define theta = tmpprs * pow(1000/lev,287/1004)'

'define dy = cdiff(lat,y) * 3.1416/180'
'define dx = cdiff(lon,x) * 3.1416/180'
'define dthetax = cdiff(theta,x)'
'define dthetay = cdiff(theta,y)'

'define dtheta = ((vgrdprs * dthetax / (cos(lat*3.1416/180) * dx)) -
(ugrdprs * dthetay / dy))/(6.37e6)'

## for the following .. have 0.5 for the first term .. but NOT the second.
This follows
## the GEMPACK formulation .. not AWIPS (I suspect an error on the web
page).

'define ipvU100 = (0.5 * (((vort(lev-100) + vort) * (theta - theta(lev-100))
/ (lev(lev-100) - lev))) + ((dtheta(lev-100) - dtheta) / (lev(lev-100) -
lev))) * 9.81e4'

-------------- end script ----------------

-----Original Message-----
From: Steven Caruso [{mailto:caruso@SOEST.HAWAII.EDU}]
Sent: June 8, 2001 6:48 PM
To: GRADSUSR@LIST.CINECA.IT
Subject: Potential vorticity


Aloha,

I was wondering if anyone had a script to calculate potential vorticity
over a defined layer.  An example is I may want to look at PV from
300-400mb.

Mahalo,
Steven Caruso


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