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[GEMPAK #BHI-235341]: Showalter Stability Index with gdplot3 ?

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  • Subject: [GEMPAK #BHI-235341]: Showalter Stability Index with gdplot3 ?
  • Date: Fri, 25 Aug 2006 10:59:17 -0600
Giovanni,

SHOW is not one of the stability parameters that is automatically calculated 
for grids (see "phelp gfunc") as are the other indicies that you mention.

Since SHOW = T500 - Tparcel(850), you can compute the pressure and temperature 
at
the LCL for a parcel lifted from 850 using the PLCL(pres,tmpc,dwpc) and
TLCL(tmpc,dwpc).

If the PLCL is greater than 500 mb,the temperature of the parcel at 500mb 
can be computed using the TMST(thte,plcl) function.

This would look like:

GLEVEL = 500
GVCORD = pres
GDPFUN = 
   plcl(pres,tmpc@850,dwpc@850)//P1 ! sub(tlcl(tmpc@850,dwpc@850),273.15)//T1 ! 
sub(tmpk,tmst(thte(P1,T1,T1),P1))
TYPE   = c
CINT   =  
LINE   = 0 ! 0 ! 5

Note that when PLCL from 850 is above 500mb, you can just use the dry adiabatic 
lapse rate to
calculate Tp500.

In the above GDPFUN, P1 and T1 represent the pressure and temperature at the 
LCL of the parcel lifted
from 850mb. In the thte function, DWPC == TMPC at the LCL. Gdpfun will fit on a 
single line
though it is wrapped in the above cut from my term.

If you did this in GDDIAG, you could then use the SGE SLT operators to combine
the values for whenthe parcel from 850 is dry. Also, you can then filter based
on values exceeding a threshold.


Steve Chiswell
Unidata User Support



> Hello Steve,
> 
> I'm successful on plotting several (kinx, ctot, vtot, totl, swet, lift)
> stability indexes, but I cannot plot showalter (show parameter name).
> I'm using GVCORD=none and glevel=0.
> 
> Any idea?
> 
> thanks,  Giovanni
> 
> 
> --
> Giovanni Dolif
> Meteorologista (Msc.) - CPTEC/INPE
> http://www.cptec.inpe.br
> Tel.: 55 - (12) 3186-8459
> 
> 


Ticket Details
===================
Ticket ID: BHI-235341
Department: Support GEMPAK
Priority: Normal
Status: Closed