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[GEMPAK #ZAN-221187]: GEMPAK Formula Question.

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  • Subject: [GEMPAK #ZAN-221187]: GEMPAK Formula Question.
  • Date: Tue, 18 Sep 2007 15:33:32 -0600
Phillip,

The BVSQ() function in the grid functions accepts an input value,
which typically is THTA (though nothing would prevent you from using THTE)
 which you chose to pass to the function.

The $GEMPAK/source/gemlib/df/dfbvsq.c routine then uses your input
grid for specified thta grid as described in the routine:

 *      BVSQ ( THTA ) = [ GRAVTY * LDF (THTA) ] / [ LAV (THTA) * DZ ]   *
 *                                                                      *
 *      DZ = change in height across the layer                          *
 *      = -( RDGAS / GRAVTY ) * LAV (THTA) *                            *
 *      ( LAV (PRES) / 1000 ) ** KAPPA * LDF (PRES) / LAV (PRES)        *
 *      in THTA coordinates                                             *

Steve Chiswell
Unidata User Support




> Hello,
> 
> My question deals with the moist Brunt-Vaisala frequency.  Does this
> algorithm just replace theta with theta-e or does the algorithm use the
> formula used in Durran and Klemp 1982?  I probably need to use the
> latter, but it would be a little messy if I tried it on gfunc or
> gdpfun.  I'm currently using version 5.9.4 for reference.  Thank you for
> you help and time.
> 
> Phillip Marzette
> 
> 
> 


Ticket Details
===================
Ticket ID: ZAN-221187
Department: Support GEMPAK
Priority: Normal
Status: Closed