Re: how to calculate potential vorticity

Dear Wei,
I am feeling difficulty to calculate the potential vorticity as you suggested me. Now I am sending you my script file I hope you will check it and suggested me like before.
thanks in advance
kalim

--- On Mon, 10/19/09, Wei Huang <huangwei@ucar.edu> wrote:

From: Wei Huang <huangwei@ucar.edu>
Subject: Re: how to calculate potential vorticity
To: "kalim ullah" <kalimrid@yahoo.com>
Date: Monday, October 19, 2009, 7:09 AM

Kalim,

Where "phi = latitude * PI/180".
Do not scale your vrt before pv, but after you get pv.

Assume your have KZ levels,

where theat = T * (100000/p) **(R/cp).

then:
at level 1: d(theta)/dp =  (theta(2) - theta(1))/(P(2) - P(1))
at level KZ: d(theta)/dp =  (theta(KZ) - theta(KZ -1))/(P(KZ) - P(KZ -1))
and other levels:  d(theta)/dp = 0.5 * (  (theta(K+1) - theta(K))/(P(K+1) - P(K))
                                                          + (theta(K) - theta(K-1))/(P(K) - P(K-1)))

Where P is in Pa.

Hope this help.

Wei Huang
huangwei@ucar.edu
VETS/CISL
National Center for Atmospheric Research
P.O. Box 3000 (1850 Table Mesa Dr.)
Boulder, CO 80307-3000 USA
(303) 497-8924

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