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19990713: Dumbest question yet

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  • Subject: 19990713: Dumbest question yet
  • Date: Tue, 13 Jul 1999 14:05:39 -0600
John,

If I did not mention in my original message to you regarding obtaining
the password to download the distribution and other instructions,
then I should have.

The User Guide is in the subdirectory:
$NAWIPS/doc/User_Guide

all the chapters are in postscript files which you can print locally.

Chapters 3 and 4 of the user guide are also available on the web in
HTML format. Chapters 3 and 4 are the parameter definitions and the
program refernce sections. You can access these pages as well as the tutorial 
from the tutorial link at:
http://www.unidata.ucar.edu/packages/gempak/tutorial/

Follow the link to #3 (GEMPAK/N-AWIPS Users Manual)

Steve Chiswell
Unidata User Support

>From: John Knox <address@hidden>
>Organization: .
>Keywords: 199907131955.NAA29935

>Dear Support,
>
>Thanks again for your help.  Now, the dumbest question yet: 
>are we supposed to have a copy of the User Guide?  Or is it 
>on-line?  I'm not aware that we have a copy--on the other 
>hand, we got GEMPAK access during my first year of teaching 
>here at Valparaiso and almost anything could have happened 
>without my remembering it.
>
>If we're supposed to have a copy but don't, how do we 
>acquire one?  This will relieve you from answering future 
>dumb questions.
>
>Thanks,
>
>John
>
>On Tue, 13 Jul 1999 10:58:27 -0600 Unidata Support 
><address@hidden> wrote:
>
>> >From: John Knox <address@hidden>
>> >Organization: .
>> >Keywords: 199907131559.JAA22150
>> 
>> >Dear Support,
>> >
>> >We've got another relatively simple question.  We need to 
>> >be precise in our calculation of potential vorticity.  
>> >While there are several options for calc'g PV, we need to 
>> >know exactly how PVOR is doing its calculations.  Where do 
>> >we look in the code for these details?
>> >
>> >Thanks for your earlier help; we were able to clear up a 
>> >long-standing problem with the calculation of divergence 
>> >tendency.
>> >
>> >Sincerely,
>> >
>> >John Knox
>> >address@hidden
>> >
>> >
>> 
>> John,
>> 
>> The grid diagnostic function calculations are shown in Appendix B of the
>> User Guide, and the code for calculating PVOR is found in:
>> $GEMPAKHOME/source/gemlib/dv/dvpvor.f
>> 
>> 
>> Here is the function header:
>>         SUBROUTINE DV_PVOR ( iret )
>> C************************************************************************
>> C* DV_PVOR                                                              *
>> C*                                                                      *
>> C* This subroutine computes the potential vorticity in a layer from     *
>> C* scalar (thermal and pressure) and vector (wind) fields:              *
>> C*                                                                      *
>> C*     PVOR ( s, V ) = - GRAVTY * AVOR ( VLAV (V) ) * LDF ( CTA ) /     *
>> C*                  ( 100 * LDF ( PRES ) )                              *
>> C*                                                                      *
>> C*                  Where: 100 converts millibars to Pascals            *
>> C*                         CTA can be THTA, THTE, or THES               *
>> C*                                                                      *
>> C* PVOR works on a layer in THTA or PRES coordinates.  In the case of   *
>> C* PRES, the vorticity of the layer averaged wind is corrected by       *
>> C* the addition of ( k cross partial V w.r.t. CTA ) dot grad (CTA).     *
>> C* PVOR generates a scalar grid.                                        *
>> 
>> 
>> Steve Chiswell
>> 
>> ****************************************************************************
>> Unidata User Support                                    UCAR Unidata Program
>> (303)497-8644                                                  P.O. Box 3000
>> address@hidden                                   Boulder, CO 80307
>> ----------------------------------------------------------------------------
>> Unidata WWW Service                        http://www.unidata.ucar.edu/     
>> ****************************************************************************
>
>------------------------------------------------
>Dr. John A. Knox
>Assistant Professor of Geography and Meteorology
>Room 15, Mueller Hall
>Valparaiso University
>Valparaiso, IN 46383
>E-mail: address@hidden
>Office Phone: 219-464-6003
>