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[GEMPAK #SYC-256075]: GEMPAK - CAPE, CIN, LI, SHOWALTER, ETC using GDPROF or NSHARP?

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  • Subject: [GEMPAK #SYC-256075]: GEMPAK - CAPE, CIN, LI, SHOWALTER, ETC using GDPROF or NSHARP?
  • Date: Tue, 07 Aug 2007 20:05:58 -0600
> Institution: Plymouth State University
> Package Version: 5.9.4
> Operating System: UNIX
> Hardware Information: UNIX
> Inquiry: Hello,
> 
> Currently I'm doing a 10-year thunderstorm climatology of northern New 
> England thunderstorms.  In this study, each thunderstorm identified 
> (thousands) will need a NARR proximity sounding at varying lat/lons.  NARR 
> .grb were succesfully converted to .grid using NAGRIB.  GDPROF only seems to 
> calculate the stability indices (CTOT,VTOT,TOTL,KINX,SWET).  Is it possible 
> to have GDPROF calculate additional indices such as CAPE, CIN, LI, SHOWALTER 
> INDEX, 0-3km shear, 0-6km shear, BRN, BRN SHEAR, etc?  I was unable to find 
> any clear documentation on this.

Evan,

The stability indicies that GEMPAK can calculate involve individual level values
such as 700mb temp, dwpt, 850 temp 500mb height etc.

I added two functions for grids available on pressure vertical coordinates:
CAPE ( PRES, HGHT, TMPC, DWPC )                                 
CINS ( PRES, HGHT, TMPC, DWPC )                                 

The values of these are the initial level of the parcel (can be surface, 
boundary or
other level). All pressure level grids will be read in so that the 
positive/negative
area can be computed from the parce versus the environment. These calculations 
become
slow on larger grids since every level has to be read in and evaluated.
An example using commonly available grids would be:
CAPE(PRES@0%none, HGHT@0%none, TMPC@2%HAGL, DWPC@2%hagl)

The 2m temp and dewpoint and surface pres and height grids are typically 
available
from NCEP models.

To do other calculations such as 0-3km shear, you can use the LYR_ functions
since you will have to interpolate between normal pressure levels of grids to
find the 3km level.

Steve Chiswell
Unidata User Support


> 
> NSHARP did successfully calculate these indices.  However, I was only able to 
> manually ingest the data into NSHARP and manually output the data into a 
> postscript file.  This study will require an automatic process and text 
> output.
> 
> Thanks in advance,
> Evan Lowery
> 
> Plymouth State University Grad Program
> 
> 
> 
> 


Ticket Details
===================
Ticket ID: SYC-256075
Department: Support GEMPAK
Priority: High
Status: Closed